1: Int J Mol Med. 2005 Feb;15(2):269-75. Functional analysis of the effect of forced activation of STAT3 on M1 mouse leukemia cells. Yoshida T, Iwamoto T, Adachi K, Yokota T, Miyake Y, Hamaguchi M. Department of Ophthalmology, Nagoya University School of Medicine, Showa-ku, Nagoya 466-8550, Japan. M1 mouse myeloid leukemia cells exhibit growth arrest and differentiation to monocytes/macrophages in response to leukemia inhibitory factor (LIF) stimulation. Although recent studies have demonstrated that STAT3 plays a central role in this process, it is unknown whether STAT3 activation alone is sufficient. To address this issue, we have established M1/STAT3ER cells, where STAT3 is selectively activated by 4-hydroxytamoxifen (4HT). 4HT stimulation did not have any effect on growth and morphology of M1/ STAT3ER cells, and did not induce the down-regulation of mRNA of c-myc and c-myb, which is necessary for M1 cell differentiation. On the other hand, mRNA of jun-B, IRF1 and p19 was increased by 4HT. DNA precipitation assay indicated that both stimulation of LIF and 4HT similarly activated STAT3ER. Introduction of a constitutive active MAP kinase kinase (MEK1) into M1/STAT3ER cells did not induce differentiation either. Together, our present data suggest that signaling other than the activation of STAT3 and MEK1 may be necessary for M1 cell-growth arrest and differentiation, while a set of early genes of LIF are induced by only STAT3 activation. PMID: 15647843 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 2: J Cell Physiol. 2004 Mar;198(3):370-6. Different roles of p38 MAPK and ERK in STI571-induced multi-lineage differentiation of K562 cells. Kohmura K, Miyakawa Y, Kawai Y, Ikeda Y, Kizaki M. Department of Internal Medicine, Keio University School of Medicine, Tokyo, Japan. STI571 is a specific tyrosine kinase inhibitor of Abl kinase. It was previously reported that STI571 induced hemoglobin synthesis in the chronic myelogenous leukemia (CML) cell line K562. However, its mechanisms remain unknown. In this study, we demonstrated that STI571 induced the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and dephosphorylation of extracellular signal-regulated kinase (ERK) in K562 cells. In contrast, the phosphorylation of c-Jun N-terminal kinases (JNK) in K562 cells was not altered by STI571. We also found that STI571 induced all the myeloid (CD11b, CD13), megakaryocytic (CD41a, CD42), and erythroid (glycophorin-A) markers on K562 cells. A p38 MAPK-specific inhibitor, SB203580, inhibited the STI571-induced multi-lineage differentiation of K562 cells, indicating that p38 MAPK is crucial for this differentiation. In contrast, SB203580 did not overcome the inhibitory effect for proliferation of K562 cells, indicating that p38 MAPK activation by STI571 does not affect cell numbers. Among the hematopoietic transcription factors, the expression level of c-myb mRNA was clearly downregulated after incubation with STI571 in K562 cells. STI571-induced downregulation of c-myb mRNA was prevented by the pretreatment of K562 cells by SB203580. Our data provides insights into how p38 MAPK and ERK pathways are involved in STI571-induced differentiation of K562 cells. Copyright 2003 Wiley-Liss, Inc. PMID: 14755542 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 3: Cell Mol Life Sci. 2003 Dec;60(12):2736-48. c-Fos but not v-Fos protein induces programmed cell death of v-myb-transformed monoblasts. Zahradnickova E, Soucek K, Sevcikova S, Smardova J, Smarda J. Department of Genetics and Molecular Biology, Faculty of Science, Masaryk University, Kotlarska 2, 611 37 Brno, Czech Republic. c-Fos and v-Fos belong to a group of proteins forming the transcription factor AP-1 that is important for regulation of proliferation, differentiation and programmed cell death in multiple cell types. In this study, we examined the role of c-Fos and v-Fos proteins in v-myb-transformed BM2 monoblasts. We show that while the v-Fos protein prolongs the G0G1 phase of the BM2 cell cycle, c-Fos leaves the cell cycle unaffected and, rather, induces programmed cell death. The apoptosis-promoting activity of the c-Fos protein is markedly enhanced in cells cultivated under serum-free conditions. c-Fos-induced apoptosis of BM2 cells occurred in the presence of Bcl-2 and was not dependent on the transcription activation function of the c-Fos protein. No differentiation-promoting activity of the Fos proteins was observed. The effects of Fos proteins on BM2 cells differ from those induced by Jun proteins, suggesting differential roles of individual components of the AP-1 transcription factor in regulation of essential cellular processes. PMID: 14685696 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 4: Prostaglandins Other Lipid Mediat. 2003 Nov;72(3-4):131-45. Lipoxygenase inhibitors enhance tumor suppressive effects of jun proteins on v-myb-transformed monoblasts BM2. Bryja V, Sedlacek J, Zahradnickova E, Sevcikova S, Pachernik J, Soucek K, Hofmanova J, Kozubik A, Smarda J. Department of Genetics and Molecular Biology, Faculty of Science, Masaryk University, Brno CZ-611 37, Czech Republic. Inhibitors of arachidonic acid (AA) conversion were described as suppressors of proliferation and inducers of differentiation of various leukemic cells. Certain AA metabolites have been shown to cooperate with Jun proteins that are important factors controlling cell proliferation, differentiation and apoptosis. Using lipoxygenase (LOX) inhibitors of various specifity we studied possible participation of lipoxygenase pathway in regulation of proliferation and apoptosis of v-myb-transformed chicken monoblasts BM2 and its functional interaction with Jun proteins. We found that nordihydroguaiaretic acid (NDGA) and esculetin (Esc) negatively regulate proliferation of BM2 cells causing accumulation in either G0/G1-phase (nordihydroguaiaretic acid) or S-phase (esculetin) of the cell cycle. BM2 cells can be also induced to undergo growth arrest and partial differentiation by ectopic expression of Jun proteins. We demonstrated that lipoxygenase inhibitors further enforce tumor suppressive capabilities of Jun proteins by inducing either more efficient cell cycle block and/or apoptosis in BM2 cells. This suggests that there is a cross-talk between the lipoxygenase- and Jun-directed pathways in regulation of differentiation and proliferation of monoblastic cells. Thus pharmacologic agents that specifically block lipoxygenase-catalyzed activity and enforce the effects of differentiation-inducers may be important components in anti-tumor therapies. PMID: 14674625 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 5: EMBO Rep. 2003 Feb;4(2):137-42. Modification with SUMO. A role in transcriptional regulation. Verger A, Perdomo J, Crossley M. School of Molecular and Microbial Biosciences G08, University of Sydney, Sydney, NSW, 2006, Australia. a.verger@mmb.usyd.edu.au Small ubiquitin-related modifier (SUMO) is a protein moiety that is ligated to lysine residues in a variety of target proteins. The addition of SUMO can modulate the ability of proteins to interact with their partners, alter their patterns of subcellular localization and control their stability. It is clear that SUMO influences many different biological processes, but recent data suggest that it is particularly important in the regulation of transcription. Indeed, several transcription factors, such as Sp3, c-Jun, c-Myb and various nuclear receptors, have recently been shown to be subject to sumoylation and, although this modification can have a positive influence, a growing body of evidence highlights its role in the negative regulation of transcription. This review summarizes recent experiments focusing on sumoylation and transcriptional repression. Publication Types: Review Review, Tutorial PMID: 12612601 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 6: Curr Opin Struct Biol. 2003 Feb;13(1):40-8. Erratum in: Curr Opin Struct Biol. 2003 Apr;13(2):262. Tahirov Tahir [corrected to Tahirov Tahir H]. Eukaryotic transcriptional regulatory complexes: cooperativity from near and afar. Ogata K, Sato K, Tahirov TH. Department of Biochemistry, Yokohama City University School of Medicine, 3-9 Fukuura, Kanazawa-ku, Yokohama 236-0004, Japan. ogata@med.yokohama-cu.ac.jp It is characteristic of eukaryotic transcription that a unique combination of multiple transcriptional regulatory proteins bound to promoter DNA specifically activate or repress downstream target genes; this is referred to as combinatorial gene regulation. Recently determined structures have revealed different modes of protein-protein interaction on the promoter DNA from near (e.g. the Runx1-CBFbeta-DNA, NFAT-Fos-Jun-DNA, GABPalpha-GABPbeta-DNA, Ets-1-Pax-5-DNA and PU.1-IRF-4-DNA complexes) and afar with DNA looping (e.g. the c-Myb-C/EBPbeta-DNA complex), and their regulatory mechanisms. Publication Types: Review Review, Tutorial PMID: 12581658 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 7: Blood. 2003 Jun 1;101(11):4322-32. Epub 2003 Jan 30. The in vivo profile of transcription factors during neutrophil differentiation in human bone marrow. Bjerregaard MD, Jurlander J, Klausen P, Borregaard N, Cowland JB. Department of Hematology, Rigshospitalet, University of Copenhagen, Denmark. malene.bjerregaard@rh.dk In vivo distribution of myeloid transcription factors during granulopoiesis was investigated by Northern and Western blotting in 3 neutrophil precursor populations from human bone marrow: immature (myeloblasts [MBs] and promyelocytes [PMs]); intermediate mature (myelocytes [MCs] and metamyelocytes [MMs]); and mature neutrophil cells (band cells [BCs] and segmented neutrophil cells [SCs]). Nonneutrophil cells were removed with magnetic-bead-coupled antibodies against CD2, CD3, CD14, CD19, CD56, CD61, glycophorin-A, and CD49d (BCs/SCs) before RNA and protein extraction. Polymorphonuclear neutrophils (PMNs) from peripheral blood depleted with anti-CD49d antibodies were also included. Expression of acute myeloid leukemia 1b (AML-1b), c-myb, GATA-1, and CCAAT/enhancer binding protein gamma (C/EBP-gamma) was seen primarily in MBs/PMs, and little expression was found in more mature cells. The level of C/EBP-alpha was constant in the bone marrow-derived cells and decreased in PMNs. C/EBP-epsilon was found primarily in MCs/MMs and was almost absent in more mature cells. Expression of C/EBP-beta, C/EBP-delta, and C/EBP-zeta was observed from the MC/MM stage onward, with peak levels in the most mature cells. The amount of PU.1 increased throughout maturation whereas the level of Elf-1 reached a nadir in MCs/MMs The PU.1 coactivator c-jun and c-jun's dimerization partner c-fos were both detectable in MCs/MMs and increased in amount with maturity. CCAAT displacement protein (CDP) was found at comparable levels at all stages of differentiation. This demonstrates a highly individualized expression of the transcription factors, which can form the basis for the heterogeneous expression of granule proteins during granulopoiesis and cell cycle arrest in metamyelocytes. PMID: 12560239 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 8: Cell Mol Life Sci. 2002 Oct;59(10):1690-705. Differential effects of v-Jun and c-Jun proteins on v-myb-transformed monoblasts. Sevcikova S, Soucek K, Kubala L, Bryja V, Smarda J. Masaryk University, Faculty of Science, Department of Genetics and Molecular Biology, Kotlarska 2, 611 37 Brno, Czech Republic. The v-myb oncogene of avian myeloblastosis virus transforms myelomonocytic cells in vitro. The line of v-myb-transformed chicken monoblasts BM2 can be induced to terminal differentiation using phorbol esters. The fact that Jun proteins are up-regulated in the phorbol ester-treated BM2 cells prompted us to investigate the role of the Jun proteins in regulation of myeloid differentiation. We ectopically expressed v-jun and c-jun in BM2 cells and evaluated their effects on differentiation and proliferation. c-Jun up-regulated the transactivation activity of v-Myb and induced a proliferation block and differentiation of BM2 cells. In contrast, v-Jun down-regulated v-Myb transactivation causing no dramatic effects on BM2 cells. This confirms that there is no strong correlation between transcriptional activation and strength of oncogenic transformation by v-Myb. Both c-Jun and v-Jun proteins affected sensitivity of BM2 cells to retinoic acid and phorbol ester. Sensitivity of BM2 cells to retinoic acid was enhanced by both Jun proteins, while sensitivity to phorbol 12-myristate 13-acetate was reduced by v-Jun. These data suggest thate Jun plays a major role in macrophage differentiation. PMID: 12475180 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 9: Biochemistry. 2002 Nov 26;41(47):13956-64. Structurally distinct modes of recognition of the KIX domain of CBP by Jun and CREB. Campbell KM, Lumb KJ. Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523-1870, USA. Gene expression is coordinated in part by interactions between transcriptional activators and other transcription factors such as coactivators. The KIX domain of the coactivator and histone acetyltransferase CREB binding protein (CBP) binds numerous mammalian and viral transcriptional activators such as BRCA1, CREB, c-Jun, c-Myb, p53, papillomavirus E2, and HTLV-1 Tax. Formation of the CREB-CBP complex depends on phosphorylation of the KID region of CREB and involves induced folding of KID upon binding a hydrophobic groove of the KIX domain of CBP. Here we investigate the formation of the complex formed by human KIX and the N-terminal activation domain of human c-Jun. The c-Jun activation domain and KID do not share significant sequence similarity. Circular dichroism spectroscopy shows that the Jun N-terminal activation domain is intrinsically disordered in isolation and that KIX binding is independent of Jun phosphorylation. In contrast to the mode of binding exhibited by CREB, NMR chemical shift mapping indicates that the c-Jun activation domain binds to a distinctly different surface of KIX than used by CREB. Moreover, NMR and sedimentation equilibrium studies show that the activation domains of c-Jun and CREB can simultaneously bind the KIX domain of CBP. The results illustrate a new mode of binding and combinatorial recruitment via the KIX domain of CBP by multiple transcriptional activators. PMID: 12437352 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 10: Int J Hematol. 2002 Jun;75(5):466-72. Transcriptional regulation of myelopoiesis. Friedman AD. Division of Pediatric Oncology, Johns Hopkins University, Baltimore, Maryland 21231, USA. adfrdman@jhmi.edu A common myeloid progenitor gives rise to both granulocytes and monocytes. The early stages of granulopoiesis are mediated by the C/EBPalpha, PU.1, RAR, CBF, and c-Myb transcription factors, and the later stages require C/EBPepsilon, PU.1, and CDP. Monocyte development requires PU.1 and interferon consensus sequence binding protein and can be induced by Maf-B, c-Jun, or Egr-1. Cytokine receptor signals modulate transcription factor activities but do not determine cell fates. Several mechanisms orchestrate the myeloid developmental program, including cooperative gene regulation, protein:protein interactions, regulation of factor levels, and induction of cell cycle arrest. Publication Types: Review Review, Tutorial PMID: 12095145 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 11: Oncogene. 2002 May 13;21(21):3377-90. Transcriptional regulation of granulocyte and monocyte development. Friedman AD. Division of Pediatric Oncology, Johns Hopkins University, Baltimore, Maryland, MD 21231, USA. adfrdman@jhmi.edu Granulocytes and monocytes develop from a common myeloid progenitor. Early granulopoiesis requires the C/EBPalpha, PU.1, RAR, CBF, and c-Myb transcription factors, and terminal neutrophil differentiation is dependent upon C/EBPepsilon, PU.1, Sp1, CDP, and HoxA10. Monopoiesis can be induced by Maf-B, c-Jun, or Egr-1 and is dependent upon PU.1, Sp1, and ICSBP. Signals eminating from cytokine receptors modulate factor activities but do not determine cell fates. Orchestration of the myeloid developmental program is achieved via cooperative gene regulation, via synergistic and inhibitory protein-protein interactions, via promoter auto-regulation and cross-regulation, via regulation of factor levels, and via induction of cell cycle arrest: For example, c-Myb and C/EBPalpha cooperate to activate the mim-1 and NE promoters, PU.1, C/EBPalpha, and CBF, regulate the NE, MPO, and M-CSF Receptor genes. PU.1:GATA-1 interaction and C/EBP suppression of FOG transcription inhibits erythroid and megakaryocyte gene expression. c-Jun:PU.1, ICSBP:PU.1, and perhaps Maf:Jun complexes induce monocytic genes. PU.1 and C/EBPalpha activate their own promoters, C/EBPalpha rapidly induces PU.1 and C/EBPepsilon RNA expression, and RARalpha activates the C/EBPepsilon promoter. Higher levels of PU.1 are required for monopoiesis than for B-lymphopoiesis, and higher C/EBP levels may favor granulopoiesis over monopoiesis. CBF and c-Myb stimulate proliferation whereas C/EBPalpha induces a G1/S arrest; cell cycle arrest is required for terminal myelopoiesis, perhaps due to expression of p53 or hypo-phosphorylated Rb. Publication Types: Review PMID: 12032776 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 12: Anal Biochem. 2002 Feb 1;301(1):8-13. Silver electrode as a sensor for determination of zinc in cell cultivation medium. Kizek R, Trnkova L, Sevcikova S, Smarda J, Jelen F. Institute of Biophysics, Academy of Sciences of the Czech Republic, Kralovopolska 135, Brno, 612 65, Czech Republic. Use of the silver electrode as a sensor for the monitoring of zinc in cell growth medium is described. Zinc at silver electrodes provides specific voltammetric signal, which is affected by solution components. Signals of zinc ions in phosphate buffer solutions with and without cell growth medium were compared. Common DMEM cell culture medium was used for the cultivation of a cell line of v-myb-transformed chicken monoblasts and its variants expressing v-jun and c-jun in a zinc-dependent manner. Electrochemical results showed zinc concentrations in the medium coincide very well with the jun expression. With respect to the low toxicity of silver for eukaryotic cells, silver electrodes represent promising tools for the determination of zinc concentrations in vivo without the potential risk of a cell culture damage. PMID: 11811961 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 13: Biochimie. 2001 Oct;83(10):969-71. JAB1/CSN5 interacts with the GAL4 DNA binding domain: a note of caution about two-hybrid interactions. Nordgard O, Dahle O, Andersen TO, Gabrielsen OS. Department of Biochemistry, University of Oslo, P.O. Box 1041 Blindern, 0316 Oslo, Norway. The Jun activation domain binding protein 1 (JAB1) was first identified as an interaction partner and coactivator of c-Jun. Subsequently, it was found to be a subunit of the COP9 signalosome (CSN) and termed CSN subunit 5 (CSN5). This complex regulates light-mediated development in plants and plays an essential role in a variety of organisms. A striking feature of JAB1/CSN5 is its reported interaction with a wide range of proteins and its modulation of their activity or stability. We applied the yeast two-hybrid system to screen for proteins interacting with the DNA-binding domain of the transcription factor c-Myb and found JAB1/CSN5 among the double-positive clones. To our surprise JAB1/CSN5 was shown to interact with the DNA-binding domain of GAL4 alone and had to be rejected as a false positive in the GAL4-based two-hybrid system. This finding emphasizes the necessity of particular caution when JAB1/CSN5 is found in two-hybrid screenings. PMID: 11728635 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 14: Mol Carcinog. 2001 Sep;32(1):28-35. Gene expression profile in BALB/c-3T3 cells transformed with beryllium sulfate. Joseph P, Muchnok T, Ong T. Molecular Epidemiology Laboratory, Toxicology and Molecular Biology Branch, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, Morgantown, West Virginia 26505, USA. Differential gene expression was studied to understand the potential molecular mechanism responsible for cell transformation and tumorigenesis induced by beryllium. Cell lines were derived from tumors developed in nude mice injected subcutaneously with BALB/c-3T3 cells morphologically transformed with beryllium sulfate. Using the Atlas mouse 1.2 cDNA expression microarray, the expression profiles of 1176 genes, belonging to several different functional categories, were studied in the tumor cells as well as in the nontransformed control cells. Expression of 18 genes belonging to two functional groups was found to be consistently and reproducibly different (at least twofold) in the tumor cells compared with the control cells. The functional groups and the differentially expressed genes are as follows: The cancer-related genes (nine genes) were the ets-related transcription factor activated by ras, colony-stimulating factor, A-myb, sky, cot1, c-fos, c-jun, c-myc, and R-ras proto-oncogenes. The DNA synthesis, repair, and recombination genes (nine genes) were the DNA replication licensing factor MCM4, the DNA replication licensing factor MCM5, the DNA mismatch repair gene PMS2, the DNA excision repair gene, the DNA mismatch repair gene MSH2, the ultraviolet excision repair gene Rad23 DNA ligase 1, Rad51, and Rad52. The differential gene expression profile was confirmed with reverse transcription-polymerase chain reaction using primers specific for the differentially expressed genes. In general, expression of the cancer-related genes was upregulated, while expression of genes involved in DNA synthesis, repair, and recombination was downregulated in the tumor cells compared with the control cells. Using c-fos and c-jun, two of the differentially expressed genes, as model genes, we have found that in the nontransformed BALB/c-3T3 cells, the beryllium-induced transcriptional activation of these genes was dependent on pathways of protein kinase C and mitogen-activated protein kinase and independent of reactive oxygen species. These results indicate that beryllium-induced cell transformation and tumorigenesis are accompanied by and are possibly a product of alterations in expression of genes related to cancer and to DNA synthesis, repair, and recombination. Copyright 2001 Wiley-Liss, Inc. PMID: 11568973 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 15: Cancer Res. 2001 Mar 1;61(5):2220-5. Altered expression of Ape1/ref-1 in germ cell tumors and overexpression in NT2 cells confers resistance to bleomycin and radiation. Robertson KA, Bullock HA, Xu Y, Tritt R, Zimmerman E, Ulbright TM, Foster RS, Einhorn LH, Kelley MR. Herman B. Wells Center for Pediatric Research, Department of Pediatrics, James Whircomb Riley Hospital for Children, Indiana University School of Medicine, Indianapolis 46202, USA. The human AP endonuclease (Ape1 or ref-1) DNA base excision repair (BER) enzyme is a multifunctional protein that has an impact on a wide variety of important cellular functions including oxidative signaling, transcription factor regulation, and cell cycle control. It acts on mutagenic AP (baseless) sites in DNA as a critical member of the DNA BER repair pathway. Moreover, Ape1/ref-1 stimulates the DNA-binding activity of transcription factors (Fos-Jun, nuclear factor-kappaB, Myb, ATF/cyclic AMP-responsive element binding protein family, HIF-1alpha, HLF, PAX, and p53) through a redox mechanism and thus represents a novel component of signal transduction processes that regulate eukaryotic gene expression. Ape1/ref-1 has also been shown to be closely linked to apoptosis associated with thioredoxin, and altered levels of Ape1/ref-1 have been found in some cancers. In a pilot study, we have examined Ape1/ref-1 expression by immunohistochemistry in sections of germ cell tumors (GCTs) from 10 patients with testicular cancer of various histologies including seminomas, yolk sac tumors, and malignant teratomas. Ape1/ref-1 was expressed at relatively high levels in the tumor cells of nearly all sections. We hypothesized that elevated expression of Ape1/ref-1 is responsible in part for the resistance to therapeutic agents. To answer this hypothesis, we overexpressed the Ape1/ref-1 cDNA in the GCT cell line NT2/D1 using retroviral gene transduction with the vector LAPESN. Using an oligonucleotide cleavage assay and immunohistochemistry to assess Ape1/ref-1 repair activity and expression, respectively, we found that the repair activity and relative Ape1/ref-1 expression in GCT cell lines are directly related. NT2/D1 cells transduced with Ape1/ref-1 exhibited 2-fold higher AP endonuclease activity in the oligonucleotide cleavage assay, and this was reflected in a 2-3-fold increase in protection against bleomycin. Lesser protection was observed with gamma-irradiation. We conclude that: (a) Ape1/ref-1 is expressed at relatively high levels in some GCTs; (b) elevated expression of Ape1/ref-1 in testicular cancer cell lines results in resistance to certain therapeutic agents; and (c) Ape1/ref-1 expression in GCT cell lines determined by immunohistochemistry and repair activity assays parallels the level of protection from bleomycin. We further hypothesize that elevated Ape1/ref-1 levels observed in human testicular cancer may be related to their relative resistance to therapy and may serve as a diagnostic marker for refractory disease. To our knowledge, this is the first example of overexpressing Ape1/ref-1 in a mammalian system resulting in enhanced protection to DNA-damaging agents. PMID: 11280790 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 16: Oncogene. 1999 Dec 9;18(52):7552-8. Protein stabilization: a common consequence of mutations in independently derived v-Myc alleles. Gavine PR, Neil JC, Crouch DH. Biomedical Research Centre, University of Dundee, Ninewells Hospital and Medical School, Dundee DD1 9SY, UK. Myc is overexpressed in many cancers as a result of gene rearrangement or amplification, but coding sequence changes which cluster in the N-terminal transactivation domain also appear to play a role in tumour progression. The prototypic v-Myc gene of MC29 virus differs from avian c-Myc by a series of mutations, including a change at a regulatory phosphorylation site within the mutational hotspot (thr-61) which is known to potentiate transformation in vitro. We now show that the mutation at thr-61 stabilizes the v-Myc protein (turnover difference) and that this single mutation is both necessary and sufficient for the phenotype. A major involvement of the proteasome in Myc degradation was confirmed, but surprisingly, a dilysine motif adjacent to thr-61 proved not to be the ubiquitin target. Two other v-Myc genes which carry a mutation at thr-61 (avian MH2) or a large deletion encompassing this domain (feline T17) were found to be stabilized to a similar extent as MC29, showing that stabilization is a common feature of independently derived Myc oncogenes. These results suggest a common selective process in the genesis of these three viral oncoproteins and a mechanistic link with Jun, Fos and Myb oncoproteins which are also stabilized relative to their cellular counterparts. PMID: 10602514 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 17: Oncogene. 1999 Nov 25;18(50):7016-25. Induction of apoptosis in U937 human leukemia cells by suberoylanilide hydroxamic acid (SAHA) proceeds through pathways that are regulated by Bcl-2/Bcl-XL, c-Jun, and p21CIP1, but independent of p53. Vrana JA, Decker RH, Johnson CR, Wang Z, Jarvis WD, Richon VM, Ehinger M, Fisher PB, Grant S. Department of Medicine, Medical College of Virginia, Richmond 23298, USA. Determinants of differentiation and apoptosis in myelomonocytic leukemia cells (U937) exposed to the novel hybrid polar compound SAHA (suberoylanilide hydroxamic acid) have been examined. In contrast to hexamethylenbisacetamide (HMBA), SAHA-related maturation was limited and accompanied by marked cytoxicity. SAHA-mediated apoptosis occurred within the G0G1 and S phase populations, and was associated with decreased mitochondrial membrane potential, caspase-3 activation, PARP degradation, hypophosphorylation/cleavage of pRB, and down-regulation of c-Myc, c-Myb, and B-Myb. Enforced expression of Bcl-2 or Bcl-XL inhibited SAHA-induced apoptosis, but only modestly potentiated differentiation. While SAHA induced the cyclin-dependent kinase inhibitor p21CIP1, antisense ablation of this CDKI increased, rather than decreased, SAHA-related lethality. In contrast, conditional expression of wild-type p53 failed to modify SAHA actions, but markedly potentiated HMBA-induced apoptosis. Finally, SAHA modestly increased expression/activation of the stress-activated protein kinase (SAPK/JNK); moreover, SAHA-related lethality was partially attenuated by a dominant-negative c-Jun mutant protein (TAM67). SAHA did not stimulate mitogen-activated protein kinase (MAPK), nor was lethality diminished by the specific MEK/MAPK inhibitor PD98059. These findings indicate that SAHA potently induces apoptosis in human leukemia cells via a pathway that is p53-independent but at least partially regulated by Bcl-2/Bcl-XL, p21CIP1, and the c-Jun/AP-1 signaling cascade. PMID: 10597302 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 18: Blood. 1999 May 1;93(9):2771-9. Mice homozygous for a truncated form of CREB-binding protein exhibit defects in hematopoiesis and vasculo-angiogenesis. Oike Y, Takakura N, Hata A, Kaname T, Akizuki M, Yamaguchi Y, Yasue H, Araki K, Yamamura K, Suda T. Department of Developmental Genetics, Differentiation, Institute of Molecular Embryology and Genetics, Kumamoto University School of Medicine, Kumamoto, Japan. CREB-binding protein (CBP) and the closely related adenovirus E1A-associated 300-kD protein (p300) function as coactivators of transcription factors such as CREB, c-Fos, c-Jun, c-Myb, and several nuclear receptors. To study the roles of CBP in embryonic development, we generated CBP homozygous mutant mouse embryos that expressed a truncated form of CBP protein (1-1084 out of 2441 residues). The embryos died between embryonic days 9.5 (E9.5) and E10.5 and exhibited a defect in neural tube closure. They appeared pale and showed decreases in erythroid cells and colony-forming cells (CFCs) in the yolk sac, suggesting defects in primitive hematopoiesis. Immunohistochemistry with an anti-PECAM antibody showed a lack of vascular network formation. Organ culture of para-aortic splanchnopleural mesoderm (P-Sp) with stromal cells (OP9) showed an autonomous abnormality of putative endothelial precursors, which may induce the microenvironmental defect in hematopoiesis. In addition, these defects were partially rescued by the addition of VEGF to this culture. Our analyses demonstrate that CBP plays an essential role in hematopoiesis and vasculo-angiogenesis. PMID: 10216070 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 19: Zhongguo Ying Yong Sheng Li Xue Za Zhi. 1997 Feb;13(1):21-4. [Effects of chronic hypoxia on the expression of oncogene jun fos and myb mRNA in rat lung] [Article in Chinese] Ran P, Ouyang N, Zhong N, Chen S. Guangzhou Institute of Respiratory Disease. This paper is to investigate the expression of oncogene jun fos and myb mRNA in the lung of rats exposed to chronic hypoxia. 15 SD rats were put in low oxygen chamber (FiO2 = 0.1), 8 hrs daily for 1, 2 and 3 weeks. Five rats breathing room air served as control. Oncogene expression in lung tissue assessed by the use of in situ hybridization. The results showed that (1) there was a slight expression of jun mRNA but not fos and myb mRNA in the control normoxic rats' lung; (2) it was found that a less expression of jun mRNA in lung after 1 week hypoxia, but after 2 week hypoxia jun mRNA elevated again and significantly increased after 3 week hypoxia as compared with that in normoxia; (3) the oncogene myb mRNA expression showed significant increase in 1 and 2 week hypoxia and returned to normal status in 3 week hypoxia; (4) after 1 to 3 week hypoxia, a significant increased expression of fos mRNA was found as compared with that in normoxia. It is suggested hypoxia may induce increased expression of proto-oncogene jun myb and fos, which may be related to proliferation of pulmonary arterial smooth muscle cells and fibroblasts. PMID: 10074303 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 20: Oncogene. 1998 Sep 10;17(10):1189-94. Normal development, oncogenesis and programmed cell death. Liebermann DA. Fels Institute for Cancer Research and Molecular Biology, Philadelphia, Pennsylvania 19140, USA. Meeting's Report -- June 2, 1998, Sugarload Estate Conference Center, Philadelphia, Pennsylvania, USA. A symposium on Normal Development, Oncogenesis and Programmed Cell Death, was held at the Sugarload Estate Conference Center, Philadelphia, Pennsylvania, USA sponsored by the Fels Cancer Institute, Temple University School of Medicine, with the support of the Alliance Pharmaceutical Corporation. The symposium was organized by Drs Dan A Liebermann and Barbara Hoffman at the Fels. Invited speakers included: Dr Andrei V Gudkov (University of Illinois) who started the symposium talking about 'New cellular factors modulating the tumor suppressor function of p53'; Dr Yuri Lazebnik (Cold Spring Harbor Laboratories) spoke about 'Caspases considered as enemies within'; Dr E Premkumar Reddy (Fels Institute, Temple University) talked about recent exciting findings in his laboratory regarding 'JAK-STATs dedicated signaling pathways'; Dr Michael Greenberg (Harvard University) spoke about 'Signal transduction pathways that regulate differentiation and survival in the developing nervous system'; Dr Richard Kolesnick's (Memorial Sloan-Kettering Cancer Center) talk has been focused at 'Stress signals for apoptosis, including Ceramide and c-Jun Kinase/Stress-activated Protein Kinase'; Dr Barbara Hoffman (Fels Institute, Temple University) described research, conducted in collaboration with Dr Dan A Liebermann, aimed at deciphering the roles of 'myc, myb, and E2F as negative regulators of terminal differentiation', using hematopoietic cells as model system. Dr Daniel G Tenen (Harvard Medical School), described studies aimed at understanding the 'Regulation of hematopoietic cell development by lineage specific transcription regulators'. Dr George C Prendergast (The Wistar Institute) talked about the 'Myc-Bin1 signaling pathway in cell death and differentiation. Dr Ruth J Muschel (University of Pennsylvania) spoke about work, conducted in collaboration with Dr WG McKenna, aimed at gaining a better understanding of 'Radioresistance and the cell cycle'. Finally Dr Donald Kufe concluded the symposium (Dana Farber Cancer Institute, Harvard Medical School) describing studies that were performed in his laboratory addressing the 'Role for the c-Abl tyrosine kinase in genetic recombination'. Publication Types: Congresses PMID: 9771961 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 21: Blood. 1998 Sep 15;92(6):1957-66. The zinc finger transcription factor Egr-1 activates macrophage differentiation in M1 myeloblastic leukemia cells. Krishnaraju K, Hoffman B, Liebermann DA. Fels Institute for Cancer Research and Molecular Biology, and Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA 19140, USA. We previously have shown that the zinc finger transcription factor Egr-1 blocked granulocytic differentiation of HL-60 cells, restricting differentiation along the monocytic lineage. Egr-1 also was observed to block granulocyte colony-stimulating factor (G-CSF)-induced differentiation of interleukin-3 (IL-3)-dependent 32Dcl3 hematopoietic precursor cells, endowing the cells with the ability to be induced by granulocyte-macrophage colony-stimulating factor (GM-CSF) for terminal differentiation along the macrophage lineage. To better understand the function of Egr-1 as a positive modulator of monocytic differentiation, in this work we have studied the effect of ectopic expression of Egr-1 on the murine myeloblastic leukemic cell line M1, which is induced for differentiation by the physiological inducer IL-6. It is shown that, unlike in HL-60 and 32Dcl3 cells, ectopic expression of Egr-1 in M1 cells resulted in activation of the macrophage differentiation program in the absence of differentiation inducer. This included the appearance of morphologically differentiated cells, decreased growth rate in mass culture, and cloning efficiency in soft agar, and expression of endogenous c-myb and c-myc mRNAs was markedly downregulated. Untreated M1Egr-1 cells also exhibited cell adherence, expression of Fc and C3 receptors, and upregulation of the myeloid differentiation primary response genes c-Jun, junD, and junB and the late genetic markers ferritin light-chain and lysozyme. Ectopic expression of Egr-1 in M1 cells also dramatically increased the sensitivity of the cells for IL-6-induced differentiation, allowed a higher proportion of M1 cells to become terminally differentiated under conditions of optimal stimulation for differentiation, and decreased M1 leukemogenicity in vivo. These findings demonstrate that the functions of Egr-1 as a positive modulator of macrophage differentiation vary, depending on the state of lineage commitment for differentiation of the hematopoietic cell type. Copyright 1998 by The American Society of Hematology. PMID: 9731053 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 22: J Biol Chem. 1998 Aug 14;273(33):21423-9. Myb-dependent regulation of thrombospondin 2 expression. Role of mRNA stability. Bein K, Ware JA, Simons M. Angiogenesis Research Center, Cardiovascular Division, Department of Medicine Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts 02215, USA. The nuclear transcription factor c-Myb, which is highly expressed in hematopoietic cells, has been shown to be functional in NIH 3T3 cells: cells that do not possess detectable levels of c-Myb. To identify endogenous target genes of c-Myb in fibroblasts, RNA isolated from NIH 3T3 cells stably transfected with a full-length or a dominant negative c-myb construct (GREMyb and GREMEn, respectively) was subjected to differential display analysis. 5'-Rapid amplification of cDNA ends of a selected band, sequencing, and a nucleotide homology search led to the identification of thrombospondin 2 (TSP 2) as the gene product repressed in GREMyb and induced in GREMEn cells. The pattern of TSP 2 expression during the cell cycle was consistent with c-myb-dependent regulation. The possibility that the identified transcript was TSP 1, a homologous product known to be repressed by v-Src, c-Jun, and v-Myc, was ruled out by using a TSP 2-specific DNA probe and by showing a distinct pattern of regulation of TSP 1 and TSP 2 expression. Nuclear run-on and TSP 2 promoter-reporter (chloramphenicol acetyltransferase) assays showed similar transcriptional levels in GREMyb and NIH 3T3 cells. However, mRNA stability studies showed a much shorter TSP 2 mRNA half-life in GREMyb compared with wild type NIH 3T3 cells, suggesting that c-myb affects TSP 2 expression via a post-transcriptional mechanism. The implications of a protooncogene-mediated suppression of TSP expression are discussed. PMID: 9694906 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 23: J Immunol. 1998 Jun 15;160(12):5898-906. Erratum in: J Immunol 1999 Jul 15;163(2):1093. CpG oligodeoxyribonucleotides rescue mature spleen B cells from spontaneous apoptosis and promote cell cycle entry. Yi AK, Chang M, Peckham DW, Krieg AM, Ashman RF. Medical Services, Department of Veterans Affairs, Iowa City, IA 52246, USA. Isolated murine splenic B cells undergo spontaneous apoptosis. Motifs containing unmethylated CpG dinucleotides in bacterial DNA or in synthetic oligodeoxynucleotides (ODN) are known to activate murine B cells. Now we show that ODN that induce spleen B cell cycle entry also inhibit spontaneous apoptosis in a sequence-specific fashion. Reversal of the CG to GC abolished activity. Methylation of the central cytosine decreased activity. When CpG is preceded by a cytosine or followed by a guanine, activity was abolished. Other substitutions at the same positions had no effect. Dose-response curves for apoptosis protection and G1 entry suggested that a uniform population of ODN recognition sites controlled downstream ODN effects. A CpG ODN with a nuclease-resistant phosphorothioate backbone (S-ODN) was also active, and increased the levels of c-myc, egr-1, c-jun, bclXL, and bax mRNA and c-Myc, c-Jun, Bax, and BclXL protein in spleen B cells. Levels of c-myb, myn, c-Ki-ras, and bcl2 mRNA remained unchanged. When protein synthesis was inhibited, at 16 h ODN-induced cell cycle entry was abolished and apoptosis protection was partially preserved. Under these conditions, c-Myc was still present, but c-Jun and BclXL were not detected. Our results suggest that CpG containing ODN motifs provide signals for both survival and cell cycle entry. Single base changes determine whether this signal proceeds through a rate-limiting step governing at least two steps in apoptosis (plasma membrane transition, DNA cleavage) and two phases of the cell cycle (G1 and S phase entry). This biologic action is associated with increased c-Myc, c-Jun, and BclXL expression. PMID: 9637502 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 24: Mol Cell Biol. 1998 Feb;18(2):989-1002. Molecular cloning reveals that the p160 Myb-binding protein is a novel, predominantly nucleolar protein which may play a role in transactivation by Myb. Tavner FJ, Simpson R, Tashiro S, Favier D, Jenkins NA, Gilbert DJ, Copeland NG, Macmillan EM, Lutwyche J, Keough RA, Ishii S, Gonda TJ. Hanson Centre for Cancer Research, Institute of Medical and Veterinary Science, Adelaide, South Australia. We have previously detected two related murine nuclear proteins, p160 and p67, that can bind to the leucine zipper motif within the negative regulatory domain of the Myb transcription factor. We now describe the molecular cloning of cDNA corresponding to murine p160. The P160 gene is located on mouse chromosome 11, and related sequences are found on chromosomes 1 and 12. The predicted p160 protein is novel, and in agreement with previous studies, we find that the corresponding 4.5-kb mRNA is ubiquitously expressed. We showed that p67 is an N-terminal fragment of p160 which is generated by proteolytic cleavage in certain cell types. The protein encoded by the cloned p160 cDNA and an engineered protein (p67*) comprising the amino-terminal region of p160 exhibit binding specificities for the Myb and Jun leucine zipper regions identical to those of endogenous p160 and p67, respectively. This implies that the Myb-binding site of p160 lies within the N-terminal 580 residues and that the Jun-binding site is C-terminal to this position. Moreover, we show that p67* but not p160 can inhibit transactivation by Myb. Unexpectedly, immunofluorescence studies show that p160 is localized predominantly in the nucleolus. The implications of these results for possible functions of p160 are discussed. PMID: 9447996 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 25: Anticancer Res. 1997 Sep-Oct;17(5B):3713-19. The apurinic/apyrimidinic endonuclease (APE/ref-1) DNA repair enzyme is elevated in premalignant and malignant cervical cancer. Xu Y, Moore DH, Broshears J, Liu L, Wilson TM, Kelley MR. Department of Pediatrics, Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis 46202, USA. The multifunctional mammalian apurinic/apyrimidinic (AP) endonuclease (APE) is responsible for the repair of AP sites in DNA. In addition, this enzyme has been shown to function as a redox factor facilitating the DNA-binding capability of JUN and FOS, HeLa AP-1, and numerous other transcription factors, including Myb, members of the CREB family and nuclear factor-kappa B. Although previously presumed to be ubiquitously expressed at comparable levels in all tissues and cell types, recent evidence has shown APE to vary significantly in its expression between tissues and even within tissues. To further characterize APE expression at various stages of cervical neoplasia, we investigated the levels of APE protein expression using immunohistochemistry in normal cervix, pre-invasive and invasive squamous lesions of the cervix, as well as in cervical cancer cell lines. We report here that the APE protein is predominantly expressed in the nuclei of cells from both primary tumors and cervical cell lines, but the level of APE protein is significantly and dramatically elevated in cervical cancer tissue. These results implicate the use of anti-APE antibodies as an effective reagent in the early detection of premalignant and malignant cancer of the cervix. These findings are suggestive that the increase of a DNA repair enzyme in cancerous cells may allow these cells to be refractive to chemotherapy. PMID: 9427767 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 26: Mol Cells. 1997 Aug 31;7(4):537-43. Characterization of the murine cyclin D2 gene: exon/intron organization and promoter activity. Jun DY, Kim MK, Kim IG, Kim YH. Department of Microbiology, College of Natural Sciences, Kyungpook National University, Taegu, Korea. Cyclin D2 is normally expressed in G1 and promotes progression through G1 of the cell cycle. From a murine genomic library constructed with spleen DNA, two overlapping genomic clones of cyclin D2 were isolated. These clones contain most of the exon of cyclin D2 except exon 5. Characterization of these clones revealed that murine cyclin D2 mRNA spans over 18 kb and 5 exons ranging from 149 to approximately 462 bp in length, and suggested that exon 5 may be at least >5 kb downstream from exon 4. Primer extension analysis of cyclin D2 mRNA isolated from murine activated T cells detected 5 putative sites of transcription initiation. These are located at - 499, - 417, - 391, - 373, and - 349 relative to the translation start site, which is given as + 1. No consensus sequence for TATA box existed at an appropriate position within the promotor region. Instead, several putative transcriptional factor binding sites for C/EBP, PEA3, AP2, NF-Y, Sp1, c-Myc, GATA-1, AP1, v-Myb, and CREB were detected. The 5'-flanking region of the cyclin D2 gene up to nucleotide - 945 shared about 61% sequence homology between mouse and human. Functional analysis of promoter activity of the 5'-flanking region of cyclin D2 suggested that the region - 1,100 to - 805 including C/EBP, PEA3, AP2, NF-Y, c-Myc, and Sp1 may have a major positive regulatory activity for expression of cyclin D2. PMID: 9339900 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 27: Int J Cancer. 1997 Aug 7;72(4):687-95. Leukemia inhibitory factor induces apoptosis and proliferation of human carcinoma cells through different oncogene pathways. Kamohara H, Sakamoto K, Ishiko T, Masuda Y, Abe T, Ogawa M. Department of Surgery II, Kumamoto University School of Medicine, Japan. Leukemia inhibitory factor (LIF) affects the growth of carcinoma cells, and we thus analyzed its underlying mechanisms. Carcinoma cells constitutively express LIF mRNA, and 23 lines (92.0%) and all (100%) of 25 lines express LIF receptor mRNAs of LIFRbeta and gp130, respectively. Exogenous addition of LIF promoted significant cell proliferation in 4 lines (MCF-7, ZR-75-1, Hs-700T and Panc-1) and suppressed cell growth in 3 lines (AZ-521, GBK-1 and HT-29). LIF significantly induced an immediate early response of genes c-fos and junB 3 hr after stimulation, but not of c-jun during the process of proliferation of MCF-7 and Hs-700T cells, with maximum levels at 30-60 min. The cell-cycle-related gene cyclin E was also induced in MCF-7 and Hs-700T cells, whereas cyclinA, cdk2, c-myc, c-myb and p53 mRNAs were not induced. On the other hand, LIF inhibited growth and increased the rate of cell death of AZ-521 and GBK-1 cells. LIF increased the number of TUNEL-positive cells in AZ-521 cells and DNA fragmentation in AZ-521 and GBK-1 cells. LIF induced apoptosis related genes c-myc and ICE during suppression of cell growth, but p53, p21, c-fos, cyclin A and cyclin E were not induced. Our results suggest that LIF is linked to cell proliferation and apoptosis in some human carcinoma cell lines. It is considered that this is related to differences in signal transduction and induction of oncogenes. PMID: 9259411 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 28: Cancer Lett. 1997 Jan 15;112(1):65-9. Selective hyperexpression of c-jun oncoprotein by glass fiber- and silica-transformed BALB/c-3T3 cells. Gao H, Brick J, Ong S, Miller M, Whong WZ, Ong T. West Virginia University, Morgantown 26506, USA. Mining and mineral processing are important industries in the United States. A large number of workers are potentially exposed to silica during mining and to glass fibers during manufacturing. There is a concern regarding lung cancer risk among workers exposed to silica and glass fibers. Our previous studies showed that both glass fibers and silica induced transformation of BALB/c-3T3 cells. In order to explore the relationship between silica and glass fiber-induced cell transformation and oncoprotein expression, the protein products of seven proto-oncogenes (c-K-ras, c-H-ras, c-sis, c-myc, c-myb, c-erb B1 and c-jun) and one tumor suppressor gene (p53) were examined in BALB/c-3T3 cells transformed by glass fibers or silica using immunoblotting with specific monoclonal or polyclonal antibodies. The results showed that all transformants, including eight induced by glass fibers and eight by silica (Min-U-Sil 5), were positive for c-jun protein expression; the level of c-jun protein was elevated 8-21-fold in these transformants. Other protooncogene proteins in transformed cells were either not detectable or not different from non-transformed cells. These results suggest that the overexpression of c-jun is common in BALB/c-3T3 transformed cells induced by glass fibers or silica. It seems, therefore, that the expression of c-jun may play an important role in the transformation process. PMID: 9029170 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 29: Recent Prog Horm Res. 1997;52:103-19; discussion 119-20. The multifunctional role of the co-activator CBP in transcriptional regulation. Goldman PS, Tran VK, Goodman RH. Vollum Institute, Oregon Health Sciences University, Portland 97201, USA. One of the most studied and best-understood examples of second messenger-regulated gene transcription involves the activation of genes by the cyclic AMP pathway: stimulation of several hormone, growth factor, and neurotransmitter receptors activates adenylyl cyclase, generating cyclic AMP that, by binding to the regulatory subunit of protein kinase A (PKA), dissociates the PKA catalytic subunit. The free catalytic subunit is transported to the nucleus where it phosphorylates and consequently activates the transcription factor CREB. This phosphorylation of CREB allows interaction with the co-activator CBP, which binds to components of the basal transcriptional machinery. CBP and its homologue p300 are targets for several viral-transforming proteins, implying that these co-activators have a more extensive role in cellular function. Indeed, recent studies have demonstrated that multiple transcription factors bind to CBP, including c-jun, c-myb, MyoD, E2F1, YY1, and members of the steroid hormone receptor superfamily, although it is not yet clear which of these transcription factors depend upon CBP for function. Determining exactly which transcriptional pathways require CBP in vivo and which genes are activated by CBP will provide an important clue in developmental regulation and cell cycle control, since mutations in the human CBP gene have been found to cause developmental abnormalities and a predisposition for some types of cancer. In this review, we will discuss the mechanisms involved in the PKA-dependent activation of CREB and describe how the co-activator CBP and its homologue are involved in this process. In addition, we will outline the various transcription factor pathways that CBP has been proposed to activate. Finally, we will discuss the possible role of CBP in cellular transformation and differentiation. Publication Types: Review PMID: 9238849 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 30: J Neurosci. 1996 Dec 1;16(23):7487-95. Metabolic and genetic analyses of apoptosis in potassium/serum-deprived rat cerebellar granule cells. Miller TM, Johnson EM Jr. Department of Neurology and Molecular Biology, Washington University School of Medicine, St. Louis, Missouri 63110, USA. Cerebellar granule cells maintained in medium containing serum and 25 mM potassium undergo an apoptotic death within 96 hr when switched to serum-free medium with 5 mM potassium. Because large numbers of apparently homogeneous neurons can be obtained, this represents a potentially useful model of neuronal programmed cell death (PCD). Analysis of the time course and extent of death after removal of either serum or K+ alone demonstrated that a fast-dying (T(1/2) = 4 hr) population (20%) responded to serum deprivation, whereas a slow-dying (T(1/2) = 25 hr) population (80%) died in response to K+ deprivation. Taking advantage of the complete death after removing both K+ and serum, changes in metabolic events and mRNA levels were analyzed in this model. Glucose uptake, protein synthesis, and RNA synthesis fell to <35% of control by 9 hr after potassium/serum deprivation, a time when 85% of the cells were still viable. The pattern of the fall in these metabolic parameters was similar to that reported for trophic factor-deprived sympathetic neurons. Most mRNAs decreased markedly after K+/serum deprivation. Levels of c-jun mRNA increased fivefold in potassium/serum-deprived granule cells; c-jun is required for cell death of sympathetic neurons. mRNA levels of cyclin D1, c-myb, collagenase, and transin remained relatively constant in potassium/serum-deprived granule cells. These data demonstrate the existence of two populations of granule cells with respect to cell death and define common metabolic and genetic events involved in neuronal PCD. PMID: 8922404 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 31: J Biol Chem. 1996 Nov 8;271(45):28138-45. CREB-binding protein activates transcription through multiple domains. Swope DL, Mueller CL, Chrivia JC. Department of Pharmacological and Physiological Sciences, Saint Louis University School of Medicine, St. Louis, Missouri 63104, USA. CREB-binding protein (CBP) functions as a coactivator molecule for a number of transcription factors including CREB, c-Fos, c-Jun, c-Myb, and several nuclear receptors. Although binding sites for these factors within CBP have been identified, the regions of CBP responsible for transcriptional activation are unknown. In this report, we show that the N-terminal half of CBP is sufficient for activation of CREB-mediated transcription and that this region contains a strong transcriptional activation domain (TAD). Both deletion of this TAD or sequestering of factors that the TAD binds using a squelching assay were found to greatly decrease the ability of CBP to activate CREB-mediated transcription. In vivo studies by others have shown that p300/CBP associates with TBP; using an in vitro approach, we show the N-terminal TAD binds TBP. We also examined the ability of the C terminus of CBP to activate transcription using GAL-CBP chimeras. With this approach, we identified two C-terminal TADs located adjacent to the c-Fos binding site. In previous studies, cAMP-dependent protein kinase A (PKA) increased the transcriptional activity of a GAL full-length CBP chimera in F9 cells, and of the C terminus in PC-12 cells. Here, we demonstrate that PKA also increased the ability of the N-terminal TADs of CBP to activate transcription in PC-12 but not F9 or COS-7 cells, suggesting that this PKA-responsiveness is cell type-specific. PMID: 8910428 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 32: Anticancer Res. 1996 Nov-Dec;16(6B):3483-9. Deoxyadenosine-resistant mouse leukemia L1210 cell lines with alterations in early response genes and p53. Cory JG, He AW, Cory AH. Department of Biochemistry, East Carolina University School of Medicine, Greenville, NC 27858, USA. L1210 cell lines selected for resistance to deoxyadenosine exhibit altered steady-state levels of the mRNA for the early response genes and p53. In the deoxyadenosine-resistant cell lines (Y8 and ED2), the levels of the mRNAs for p53 and c-jun were markedly decreased while the steady-state levels for mRNAs for c-myc, c-fos and jun B were elevated in the Y-8 and ED2 cell lines. The levels of the mRNAs for PCNA and c-myb were the same in the wild type and mutant cell lines. The levels of the mRNAs for krox-24 were extremely low in the wild type and mutant cell lines. Cycloheximide (CHX) treatment of the cells resulted in the increase in the mRNA levels for c-jun, jun B, krox 24 and p53 in the Y-8 and ED2 cell lines. The time courses and the extents of the increases in the mRNA levels following CHX treatment were not the same for all of these mRNAs. The level of p53 RNA increased with no lag following CHX treatment while the levels of the mRNAs for c-myc, c-jun and krox-24 increased after a one-hour lag period. The level of the mRNA for p53 and c-myc increased 20- and 7-fold, respectively while the mRNA level for knox-24 increased 80-fold following CHX treatment. The Y8 and ED2 cell lines that lack steady-state levels of p53 show decreased sensitivity to cisplatin and increased frequency of gene amplification as measured by PALA resistance in a manner similar to other cell lines lacking p53. On the other hand, the ED2 and Y8 cell lines do not show a G1-block in response to PALA treatment. The cell lines appear to offer an experimental system in which to study the interactions between/among these early response genes and the p53-dependent and independent pathways. PMID: 9042210 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 33: Br J Rheumatol. 1996 Oct;35(10):933-42. Oncoprotein expression in human synovial tissue: an immunohistochemical study of different types of arthritis. Roivainen A, Soderstrom KO, Pirila L, Aro H, Kortekangas P, Merilahti-Palo R, Yli-Jama T, Toivanen A, Toivanen P. Turku Immunology Centre, Department of Medical Microbiology, Turku University, Finland. Based on the fact that synovial lining cells have some properties of transformed-appearing cells, we have examined the expression of Myc, Myb, Fos, Jun and Ras oncoproteins in synovial tissues from patients with different types of arthritis. Formalin-fixed and paraffin-embedded sections of synovial tissue from 12 patients with rheumatoid arthritis (RA), 14 with reactive arthritis (ReA), nine with other seronegative arthritis (OSA), seven with bacterial arthritis (BA), eight with probable bacterial arthritis (PBA) and eight with osteoarthritis (OA) were studied using the immunoperoxidase staining technique. The oncoproteins studied were expressed both in the synovial lining layer and in the sublining layer, consisting of lymphocytes, other inflammatory cells and blood vessels. Among the six disease entities, RA and OA appeared to be the most distinct, whereas the results obtained for ReA and OSA, and on the other hand for BA and PBA, closely resembled each other. The expression of Myc, Myb, Fos and Jun was significantly correlated both to the degree of synovial hypercellularity and the synovial lymphocytic infiltration. For Ras, such a correlation could not be seen. We conclude that we find no evidence of a cell lineage-specific or a disease-specific abnormality of proto-oncogene products in RA, and the expression of these oncoproteins is consistent with inflammation rather than with any primary abnormality of cell growth. PMID: 8883430 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 34: Cell Growth Differ. 1996 Aug;7(8):1039-50. Terminally differentiated skeletal myotubes are not confined to G0 but can enter G1 upon growth factor stimulation. Tiainen M, Pajalunga D, Ferrantelli F, Soddu S, Salvatori G, Sacchi A, Crescenzi M. Molecular Oncogenesis Laboratory Regina Elena Cancer Center, Rome, Italy. Terminally differentiated cells are specialized cells unable to proliferate that constitute most of the mammalian body. Despite their abundance, little information exists on the characteristics of cell cycle control in these cells and the molecular mechanisms that prevent their proliferation. They are generally believed to be irreversibly restricted to the G0 state. In this report, we define some features of a paradigmatic terminally differentiated system, the skeletal muscle, by studying its responses to various mitogenic stimuli. We show that forced expression of a number of cell cycle-regulatory genes, including erbB-2, v-ras, v-myc, B-myb, ld-1, and E2F-1, alone or in combinations, cannot induce terminally differentiated skeletal muscle cells (myotubes) to synthesize DNA. However, serum-stimulated myotubes display a typical immediate-early response, including the up-regulation of c-fos, c-jun, c-myc, and ld-1. They also elevate the expression of cyclin D1 after 4 hours of serum treatment. All these events take place in myotubes in a way that is indistinguishable from that of quiescent, undifferentiated myoblasts reactivated by serum. Moreover, pretreatment with serum shortens the time required by E1A to induce DNA synthesis, confirming that myotubes can partially traverse G1. Serum growth factors do not activate late-G1 genes in myotubes, suggesting that the block that prevents terminally differentiated cells from proliferating acts in mid-G1. Our results show that terminally differentiated cells are not confined to G0 but can partially reenter G1 in response to growth factors; they contribute to a much-needed definition of terminal differentiation. The important differences in the control of the cell cycle between terminally differentiated and senescent cells are discussed. PMID: 8853900 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 35: Biochem Biophys Res Commun. 1996 May 15;222(2):595-600. Stimulation of c-jun and c-myb in rat Sertoli cells following exposure to retinoids. Page KC, Heitzman DA, Chernin MI. Biology Department, Bucknell University, Lewisburg, Pennsylvania 17837, USA. Circulating hormones are engaged in initiating and controlling the process of spermatogenesis, however, the Sertoli cell tight junctions prevent these substances from directly influencing the spermatogenic cells. Thus, the Sertoli cells play a vital role in regulating the spermatogenic process. Our studies correlate retinoid action with the transactivation of genes which encode the transcription factors, Jun and Myb, in the Sertoli cells of the rat testis, a retinol-dependent organ. We examined the mRNA levels for the protooncogene, c-jun, a member of the AP-I transcription complex, as well as mRNA levels for the protooncogene, c-myb, following retinoid stimulation. The major changes observed were a significant up-regulation in c-jun mRNA beginning at 30 min which reached a four-fold peak over controls at 1 h while the c-myb mRNA level exhibited a delay in up-regulation which rose abruptly to a significant three-fold peak over controls at 1 h. Interestingly, a variation in transcript size for c-jun (5.4 kb) was also detected in rat Sertoli cells. The significant 50% rise in the c-jun mRNA levels at 30 min prior to the rapid rise in the c-myb message at 1 h suggests that Jun may be involved in the transactivation of c-myb gene expression. These data support the model that retinoid modulation of these immediate early genes is the first step in a process which initiates a cascade of vitamin A-inducible gene expression in rat Sertoli cells necessary for maintaining spermatogenesis. PMID: 8670250 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 36: Leuk Res. 1996 May;20(5):429-39. c-myb intron I protein binding and association with transcriptional activity in leukemic cells. Dooley S, Seib T, Welter C, Blin N. Institut fur Humangenetik, Universitat des Saarlandes, Homburg, Germany. hgsdoo@med-rz.uni-sb.de Specific binding of nuclear proteins to the region of transcriptional attenuation has been shown to modulate the expression of c-myb, a nuclear proto-oncogene preferentially expressed in lympho-hematopoietic cells. Here, it plays an important role in processes of differentiation and proliferation. The mechanism that regulates c-myb expression is not yet fully understood. The block of transcriptional elongation which has been mapped to a 1 kb region within murine intron 1 may represent one regulatory pathway. The DNA sequences containing the transcriptional pause site are well conserved between murine and human species, thus Implying similar transcription-control strategies. We compared the binding potential of nuclear extracts (from human fibroblasts and MOLT4 as well as murine NIH3T3- and 70Z/3B- cell lines) to oligonucleotide sequences previously shown to be target binding sites in the murine system. One complex containing a 70 D protein was found to be associated specifically with transcriptionally active leukemia cells. We performed transient expression studies with a CAT reporter construct containing this putative enhancer sequence and yielded significant CAT activity. We identified further a putative 20 kD repressor protein in transcriptionally silent cells and demonstrated that c-Jun is part of an ubiquitously present complex. Our results confirm the participation of intron 1 in transcriptional regulation of the c-myb gene (in mouse and human) and implicate multiple and complex regulatory mechanisms of activation during myelomonocytic differentiation and leukemic cell growth control. PMID: 8683983 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 37: Dig Dis Sci. 1996 Apr;41(4):660-9. Expression of protooncogene-encoded mRNA by colonic epithelial cells in inflammatory bowel disease. Alexander RJ, Panja A, Kaplan-Liss E, Mayer L, Raicht RF. Department of Veterans Affairs Medical Center, New York, New York 10010, USA. Protooncogenes are cell cycle-related genes that are involved in cell growth of proliferation. Alterations in the level of expression of these genes, or expression of aberrant gene productions, have been observed in tumors and precancerous conditions. To determine if expression of these genes is altered in patients with inflammatory bowel disease (IBD) --who are at risk for development of colon cancer--we assayed transcripts of 15 protooncogenes in colonic epithelial cells of IBD patients and controls. Nine of these genes (H-ras, c-myc, c-fos, c-jun, junB, N-myc, c-abl, c-yes, and p53) were expressed in epithelial cells, whereas two (RB1 and N-ras) were not. expression of four other genes (c-src, K-ras, c-raf, and c-myb) was observed, but the intensity of these bands was too low for densitometric analysis. The steady-state levels of transcripts of H-ras and five nuclear protooncogenes (c-myc, c-fos, c-jun, junB, and N-myc) were lower in epithelial cells from involved or uninvolved IBD samples than in normal epithelial cells from either sporadic colon cancer or diverticulitis patients. The level of c-fos mRNA was two- to threefold higher in involved than in uninvolved areas of the colons of two ulcerative colitis (UC) patients, but not in one Crohn's disease (CD) patient. Message abundance of c-abl transcripts was two- to threefold lower in UC epithelial cells than in either the CD or control samples. The steady-state level of c-yes-encoded mRNA was considerably higher in IBD patients resected for colon cancer than in patients resected for active chronic IBD or in controls. The level of p53 message was constant in these samples. Increased levels of c-fos mRNA in involved UC relative to uninvolved UC may be related to the disease process. Decreased expression of c-abl transcript in UC may be a diagnostic marker for UC and may be related to the rate of cell turnover in these diseases. Enhanced expression of c-yes in IBD patients with tumors compared to active chronic IBD and controls suggests that expression of this gene may be a marker for development of colon cancer in IBD. PMID: 8674385 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 38: Crit Rev Oncog. 1996;7(1-2):49-64. Oncogene- and tumor-suppressor gene-related proteins in plants and fungi. Loidl A, Loidl P. Department of Microbiology, University of Innsbruck-Medical School, Austria. Protooncogene- and tumor-suppressor gene proteins serve essential functions in the regulation of proliferation and differentiation of cells. Abnormal regulation or mutation of these genes, or transformation with retroviral homologs, may lead to tumor development in animals. In contrast to vertebrates, only few data on these genes exist in plants and fungi. Plant nuclear protooncogene homologs, such as myb and myc have multiple regulatory functions in metabolic pathways not existing in mammalian cells; they are involved in the complex regulation of anthocyanin (purple pigment) and phlobaphene (red pigment) biosynthesis, lignin production, trichome differentiation, dehydration stress gene expression and seed development. Apart from these well-characterized roles in plant-specific pathways, few experimental data have been reported on a functional significance in growth and development. A screening for nuclear protooncogene- and tumor-suppressor gene-related proteins in the myxomycete Physarum polycephalum revealed the existence of homologs of vertebrate c-myc, c-fos, c-jun, p53, and retinoblastoma proteins during the synchronous cell cycle or sclerotization. The p53 homologs of Physarum and Zea mays were shown to be specific for quiescent stages of their life cycles. Plants and lower eukaryotes, such as fungi, may be useful experimental systems to elucidate novel functions of protooncogene- and tumor-suppressor proteins in cell cycle regulation and development, or to reveal target genes that might be difficult to identify in complex mammalian systems. Recent data indicate that oncogenes and tumor suppressors in animals have more cellular targets than originally proposed; some of these might be as unexpected as in plant secondary metabolism. Publication Types: Review Review, Tutorial PMID: 9109497 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 39: Br J Rheumatol. 1995 Sep;34(9):805-8. Oncogene expression in synovial fluid cells in reactive and early rheumatoid arthritis: a brief report. Roivainen A, Isomaki P, Nikkari S, Saario R, Vuori K, Toivanen P. Department of Medical Microbiology, Turku University, Finland. Since it has been implied that cellular oncogenes might have a role in the pathogenesis of rheumatoid arthritis (RA), we have examined the expression of c-myc, c-myb, c-fos, c-jun and c-Ha-ras oncogenes in the cells from synovial fluid (SF) and peripheral blood (PB) of patients with reactive arthritis (ReA) and early RA. Oncogene expression was studied using RNA hybridizations with 32P-labelled probes. From the SF, mononuclear and granulocyte cell fractions were used separately. Significant differences between ReA and RA were observed only for c-myb in PB mononuclear cells and c-jun in SF granulocytes. Regarding the expression of c-myc, c-fos and c-Ha-ras oncogenes, no difference between ReA and RA was observed. Comparison to normal controls was made using PB mononuclear cells; only the expression of c-fos tended to be slightly increased in RA, without statistical significance, however. We conclude that oncogene activation in the synovial inflammation is not a phenomenon specific for RA. PMID: 7582717 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 40: Biochem Biophys Res Commun. 1995 Aug 24;213(3):789-95. Coexpression pattern of c-myc associated genes in a small cell lung cancer cell line with high steady state c-myc transcription. Dooley S, Wundrack I, Blin N, Welter C. Department of Human Genetics, Univ of Saarland, Homburg, Germany. The c-Myc protein is involved in cellular transformation and mitogenesis, but also works as a potent inducer of differentiation and programmed cell death. Max as an obligate heterodimeric partner for Myc mediates its functions as a specific transcriptional activator and a transforming protein. Mad and Mxi1 proteins both heterodimerize with Max and compete with each other for limiting amounts of Max. Transcriptional activation by Myc can be suppressed by increasing the amount of Mad or Mxi1. This report shows the expression pattern of these Myc related factors at the mRNA level in a small cell lung cancer (SCLC) cell line (GLC4) which is characterized by c-myc amplification and strong constitutive c-myc overexpression. We found these genes transcriptionally active but uninfluenced from high c-myc transcription. Max was constantly transcribed at a relatively low level during cell cycle progression. Mad and mxi1 mRNA was at a surprisingly high level in proliferating cells. Mad was further upregulated and mxi1 was downregulated to basal levels during serum starvation of the cells. We further analyzed the activity of c-fos, c-jun, c-myb and nm23 which are described to be involved in c-myc transcriptional activation, c-jun and c-fos were not constitutively activated and can be excluded as regulators. High steady state c-myc in contrast influences the serum stimulated transient activation mechanism of these two genes. We identified high copy number nm23 mRNA whose role as a putative c-myc transcriptional activator is under investigation. Our results indicate that constitutive overexpression of c-myc does not require the activity of the nuclear oncogenes tested and that the m-RNA expression pattern of functionally related proteins is not influenced. PMID: 7654239 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 41: J Virol. 1995 Mar;69(3):1842-50. Human immunodeficiency virus type 1 Nef protein inhibits activation pathways in peripheral blood mononuclear cells and T-cell lines. Greenway A, Azad A, McPhee D. AIDS Cellular Biology Unit, National Centre in HIV Virology Research, Macfarlane Burnet Centre for Medical Research, Fairfield, Victoria, Australia. Human immunodeficiency virus type 1 (HIV-1) Nef protein causes the loss of cell surface CD4 and interleukin-2 (IL-2) receptor (Tac) from peripheral blood mononuclear cells (PBMC) and CD4+ T-cell lines. As both CD4 and the IL-2 receptor play crucial roles in antigen-driven helper T-cell signalling and T-cell proliferation, respectively, the role of Nef in the viral life cycle may be to perturb signalling pathways emanating from these receptors. However, the intracellular targets for Nef that result in receptor down-regulation are unknown. Using a recombinant glutathione S-transferase-full-length 27 kDa Nef (Nef27) fusion protein, produced in Escherichia coli by translation from the first start codon of HIV-1 nef clone pNL4-3, as an affinity reagent to probe cytoplasmic extracts of MT-2 cells and PBMC, we have shown interaction with at least seven host cell protein species ranging from 24 to 75 kDa. Immunoblotting identified four of these proteins as p56lck, CD4, p53, and p44mapk/erk1, all of which are intimately involved in intracellular signalling. To assess the relevance of these interactions and further define the biochemical activity of Nef in signal transduction pathways, highly purified Nef27 protein was introduced directly into PBMC by electroporation. Nef27-treated PBMC showed reduced proliferative responsiveness to exogenous recombinant IL-2. Normally, stimulation of T-cells by IL-2 or phorbol 12-myristate 13-acetate provokes both augmentation of p56lck activity and corresponding posttranslational modification of p56lck. These changes were also inhibited by treatment of PBMC with Nef, suggesting that Nef interferes with activation of p56lck and as a consequence of signalling via the IL-2 receptor. Further evidence for Nef interfering with cell proliferation was the decreased production of the proto-oncogene c-myb, which is required for cell cycle progression, in Nef-treated MT-2 cells. In contrast to the binding characteristics and biological effects of Nef27, the alternate 25-kDa isoform of Nef (Nef25) produced by translation from the second start codon of HIV nef pNL4-3 (57 nucleotide residues downstream) was shown to interact with only three cellular proteins of approximately 26, 28, and 56 kDa from PBMC and MT-2 cells, one of which was identified as p56lck. Also, proliferation and posttranslational modification of p56lck in response to IL-2 stimulation were not profoundly affected by treatment of PBMC with Nef25 compared with Nef27.(ABSTRACT TRUNCATED AT 400 WORDS) PMID: 7853525 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 42: EMBO J. 1995 Feb 1;14(3):473-83. Differential roles of PI3-kinase and Kit tyrosine 821 in Kit receptor-mediated proliferation, survival and cell adhesion in mast cells. Serve H, Yee NS, Stella G, Sepp-Lorenzino L, Tan JC, Besmer P. Molecular Biology Program, Sloan Kettering Institute, New York, NY 10021. The pleiotropic effects of the Kit receptor system are mediated by Kit-Ligand (KL) induced receptor autophosphorylation and its association with and activation of distinct second messengers, including phosphatidylinositol 3'-kinase (PI3-kinase), p21ras and mitogen-activated protein kinase (MAPK). To define the role of PI3-kinase, p21ras and MAPK in Kit-mediated cell proliferation, survival and adhesion in bone marrow-derived mast cells (BMMC), mutant Kit receptors were expressed in Wsh/Wsh BMMC lacking endogenous c-kit expression. The introduction of both murine Kit(S) and KitL (isoform containing a four amino acid insert) into Wsh/Wsh BMMC restored KL-induced proliferation, survival and adhesion to fibronectin, as well as activation of PI3-kinase, p21ras and MAPK, and induced expression of c-fos, junB, c-myc and c-myb mRNA. Substitution of tyrosine 719 in the kinase insert with phenylalanine (Y719F) abolished PI3-kinase activation, diminished c-fos and junB induction, and impaired KL-induced adhesion of BMMC to fibronectin. In addition, the Y719F mutation had partial effects on p21ras activation, cell proliferation and survival, while MAP kinase activation was not affected. On the other hand, Y821F substitution impaired proliferation and survival without affecting PI3-kinase, p21ras and MAPK activation, and induction of c-myc, c-myb, c-fos and c-jun mRNA, while KL-induced cell adhesion to fibronectin remained intact. In agreement with a role for PI3-kinase in Kit-mediated cell adhesion, wortmannin blocked Kit-mediated cell adhesion at concentrations known to specifically inhibit PI3-kinase. We conclude, that association of Kit with p85PI3-K, and thus with PI3-kinase activity, is necessary for a full mitogenic as well as adhesive response in mast cells. In contrast, tyrosine 821 is essential for Kit-mediated mitogenesis and survival, but not cell adhesion. PMID: 7532131 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 43: J Invest Dermatol. 1995 Jan;104(1):78-82. Changes in expression of apoptosis-associated genes in skin mark early catagen. Seiberg M, Marthinuss J, Stenn KS. Skin Biology Research Center, R.W. Johnson Pharmaceutical Research Institute, Raritan, NJ 08869-0602. Programmed cell death is central to hair biology, as the hair follicle undergoes cycles of growth (anagen), regression (catagen), and rest (telogen). During catagen, the hair follicle shortens via a pathway of programmed cell death and apoptosis. The molecular mechanisms involved in this process have not been elucidated yet. Using reverse transcriptase-polymerase chain reaction, we examined in this study the expression in total skin, throughout one hair cycle, of a series of regulatory genes associated with apoptosis. We show that gene expression within skin is hair-cycle-dependent. Transforming growth factor-beta was expressed immediately before catagen; therefore, it might be involved in the early signaling of this process. Tumor necrosis factor-beta was expressed during catagen and might be involved in follicular apoptosis. Several proto-oncogenes and transcription factors have been described in the regulation of apoptosis in other systems. Here we show that the transcript levels of c-myc, c-myb, and c-jun changed immediately before or during early catagen and thus could be involved in the signaling or regulation of catagen. Levels of p53 remained constant throughout anagen and catagen, suggesting that p53 is not involved in the developmentally induced apoptosis of the hair follicle. The variable expression throughout the hair cycle of the genes described demonstrates the dynamic changes of the skin and underscores the importance of studying the complete hair cycle when characterizing any molecule in skin. PMID: 7798646 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 44: Pathologe. 1994 Dec;15(6):321-30. [Oncogenes and tumor suppressor genes in the pathogenesis of lung tumors] [Article in German] Wiethege T, Voss B, Muller KM. Institut fur Pathologie, Berufsgenossenschaftliche Kliniken Bergmannsheil, Bochum. The recent results obtained from investigations based on molecular biological techniques have led to a better understanding of recurrent genetic causes important for the pathogenesis of tumors. Several genes have been identified as being involved in the development of cancer. In many cases, the activation of oncogenes or the inactivation of tumor-suppressor genes is the predominant reason for cancerogenic cell transformation. Functional dysregulation is frequently the consequence of mutations, resulting in an alteration of the primary structure of the DNA. As our understanding of the nature, function, and interaction of these genes evolves, new opportunities for early diagnosis, classification, prevention, and treatment of malignant tumors will arise. The present report summarizes the current molecular biological aspects of several oncogenes (erbB, ras, myc, raf, fos, jun, bcl, mdm2, myb, kit CSF1R, met) and tumor suppressor genes (p53, rb, mts) involved in lung-cancer development with respect to the pathology of lung tumors, including the importance of these genes as far as the clinical course of the disease is concerned. Publication Types: Review Review, Tutorial PMID: 7855100 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 45: J Cell Biol. 1994 Dec;127(6 Pt 1):1717-27. Altered gene expression in neurons during programmed cell death: identification of c-jun as necessary for neuronal apoptosis. Estus S, Zaks WJ, Freeman RS, Gruda M, Bravo R, Johnson EM Jr. Department of Molecular Biology, Washington University School of Medicine, St. Louis, Missouri 63110. We have examined the hypothesis that neuronal programmed cell death requires a genetic program; we used a model wherein rat sympathetic neurons maintained in vitro are deprived of NGF and subsequently undergo apoptosis. To evaluate gene expression potentially necessary for this process, we used a PCR-based technique and in situ hybridization; patterns of general gene repression and selective gene induction were identified in NGF-deprived neurons. A temporal cascade of induced genes included "immediate early genes," which were remarkable in that their induction occurred hours after the initial stimulus of NGF removal and the synthesis of some required ongoing protein synthesis. The cascade also included the cell cycle gene c-myb and the genes encoding the extracellular matrix proteases transin and collagenase. Concurrent in situ hybridization and nuclear staining revealed that while c-jun was induced in most neurons, c-fos induction was restricted to neurons undergoing chromatin condensation, a hallmark of apoptosis. To evaluate the functional role of the proteins encoded by these genes, neutralizing antibodies were injected into neurons. Antibodies specific for either c-Jun or the Fos family (c-Fos, Fos B, Fra-1, and Fra-2) protected NGF-deprived neurons from apoptosis, whereas antibodies specific for Jun B, Jun D, or three nonimmune antibody preparations had no protective effect. Because these induced genes encode proteins ranging from a transcription factor necessary for death to proteases likely involved in tissue remodeling concurrent with death, these data may outline a genetic program responsible for neuronal programmed cell death. PMID: 7798322 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 46: Blood. 1994 Nov 1;84(9):3095-104. Growth arrest and terminal differentiation of leukemic myelomonocytic cells induced through ligation of surface CD23 antigen. Ouaaz F, Sola B, Issaly F, Kolb JP, Davi F, Mentz F, Arock M, Paul-Eugene N, Korner M, Dugas B, et al. Molecular Immuno-Hematology Group, Pitie-Salpe-triere Hospital, Paris, France. Acute myelogenous leukemia (AML) cells express CD23 surface antigen after in vitro treatment with various cytokines, including interleukin-4 (IL-4) and interferon gamma. Subsequent ligation of CD23 by specific monoclonal antibody (MoAb) induces substantial morphologic and functional modifications in these cells. In the present study, we investigated the role of CD23 in the proliferation and the maturation of leukemic cells from AML patients or the U937 cell line. CD23+ cell treatment with CD23 MoAb inhibited the proliferation of leukemic cells. This correlated with their terminal differentiation after 7 to 9 days incubation because they (1) definitively lost their growth capacity; (2) adhered to culture flasks and became monocyte/macrophage-like; and (3) expressed mature monocyte markers including nonspecific esterases. Intracellular mechanism of this antitumoral effect was then analyzed in U937 cells. Induction of high-density surface CD23 expression by IL-4 or granulocyte-macrophage colony-stimulating factor coincided with a transient decrease of U937 cell proliferation. CD23 ligation during this low-proliferative phase induced a rapid activation of L-arginine-dependent pathway and the intracellular accumulation of cyclic guanosine monophosphate and cyclic adenosine monophosphate (cAMP). Induction of these early messengers was followed by the activation of nuclear factor-kB transcription factor and the modulation of proto-oncogene expression by U937 cells. Whereas U937 cell treatment with IL-4 decreased c-fos/c-jun expression, CD23 MoAb reinduced c-fos/c-jun and promoted the expression of cell maturation-associated proto-oncogenes junB and c-fms, during the first 24 hours. Both IL-4 and CD23 MoAb downregulated the expression of c-myb. CD23 ligation also induced the production of TNF alpha by U937 cells. Inhibitors of cAMP and nitric oxide reversed CD23-mediated modification in U937 cells. These data evidence the ability of CD23 surface antigen to mediate terminal differentiation of early leukemic myelomonocytic cells. PMID: 7949182 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 47: Leuk Res. 1994 Aug;18(8):577-85. Interferon-alpha-2b downregulation of oncogenes H-ras, c-raf-2, c-kit, c-myc, c-myb and c-fos in ESKOL, a hairy cell leukemic line, results in temporal perturbation of signal transduction cascade. Harvey WH, Harb OS, Kosak ST, Sheaffer JC, Lowe LR, Heerema NA. Department of Biology, Earlham College, Richmond, IN 47374-4095. ESKOL, a B-lymphoblastoid cell line consisting of late differentiated cells, resembles hairy cell leukemia (HCL). It is pseudodiploid with a deleted 7q and an unbalanced translocation between chromosomes 4 and 6. It was screened by Northern hybridization for oncogenes, including H-ras, c-raf-2 (c-raf1p1), c-kit, c-myc, c-myb, c-fos, Fim-1, c-jun, ski, and c-mos, which are believed to contribute to B-cell differentiation and maturation. Interferon-alpha-2b (IFN) downregulates the expression of H-ras, c-raf-2, c-kit, c-myc, c-myb, c-fos, as determined by Northern hybridization of RNA isolated from cells harvested at time points during a 30 h time course. Downregulation of oncogenes H-ras, c-raf-2, c-kit, whose proteins are associated with cell surfaces or are cytosolar transducers, occurs before those oncogenes c-myc, c-myb, and c-fos, whose products are DNA binding proteins. This suggests a temporal perturbation of signal transduction by IFN. No change in oncogene expression occurred in non-treated cells nor were these oncogenes expressed in the non-transformed B-lymphoblast cell line, Wil-2, under the same treatment regimen. The basis for the IFN perturbation is not understood; yet the role of these oncogenes as signal transducers in differentiation and proliferation of human hematopoietic progenitors is unfolding, and ESKOL is an excellent system in which to study this phenomenon. PMID: 7520517 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 48: Nucleic Acids Res. 1994 Jul 11;22(13):2466-75. The carboxyterminus of human c-myb protein stimulates activated transcription in trans. Vorbrueggen G, Kalkbrenner F, Guehmann S, Moelling K. Max-Planck-Institut fur Molekulare Genetik, Abteilung Schuster, Berlin, Germany. The cellular c-myb gene encodes a transcription factor composed of a DNA-binding domain, a transactivating domain and a regulatory domain located at its carboxy (C-) terminus. The latter one is deleted in the transforming viral protein v-Myb. Here we show that deletion of the C-terminus of c-Myb increases the transcriptional transactivation activity of c-Myb defining it as cis-acting negative regulatory domain. Cotransfection of the C-terminus in an in vivo competition assay causes stimulation of the transcriptional activity of various v- and c-Myb expression constructs in trans. The effect is dose-dependent and independent of the kind of DNA-binding domain, since c-Myb as well as GAL4-c-Myb chimaeras can be stimulated in trans. Other transcription factors, such as GAL4-VP16, GAL4, c-Jun or C/EBP beta are also stimulated by the cotransfected C-terminus. In contrast, human B-Myb is not stimulated by the c-Myb C-terminus in trans. The data suggest that the C-terminus of c-Myb may interact with a cellular inhibitor which is part of the protein complex mediating activated transcription and may stimulate in trans by sequestering away such an inhibitor. Binding of c-Myb to a putative inhibitor would explain differences between c-Myb in comparison to B- and v-Myb in transcriptional regulation. PMID: 8041607 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 49: Stem Cells. 1994 Jul;12(4):352-69. Differentiation primary response genes and proto-oncogenes as positive and negative regulators of terminal hematopoietic cell differentiation. Liebermann DA, Hoffman B. Fels Institute for Cancer Research and Molecular Biology, Temple University, School of Medicine, Philadelphia, Pennsylvania 19140. By genetically manipulating hematopoietic cells of the myeloid lineage, including both normal cells and differentiation inducible leukemic cell lines, evidence was obtained to indicate that myeloid differentiation primary response (MyD) genes and proto-oncogenes, which are known to control cell growth, function as positive and negative regulators of terminal hematopoietic cell differentiation, which is associated with inhibition of cell growth, and, ultimately programmed cell death (apoptosis). Interferon regulatory factor-1 (IRF-1), an MyD gene induced by Interleukin 6 (IL-6) or Leukemia Inhibitory factor (LIF), plays a role in growth inhibition associated with terminal differentiation. Leucine zipper transcription factors of the fos/jun family, also identified as MyD genes, function as positive regulators of hematopoietic cell differentiation, increasing the propensity of myeloblastic leukemia cells to be induced for differentiation in vitro, and reducing the aggressiveness of their leukemic phenotype in vivo. The zinc finger transcription factor EGR-1, an MyD gene specifically induced upon macrophage differentiation, was shown to be essential for and to restrict differentiation along the macrophage lineage. Finally, evidence has been accumulating to indicate that the novel MyD genes--MyD116, MyD118 and gadd45 (a member in the MyD118 gene family)--play a role in growth arrest and apoptosis of hematopoietic cells, as well as other cell types. The proto-oncogenes c-myc and c-myb, known to regulate cellular growth, were shown to function as negative regulators of terminal differentiation. Both c-myc and c-myb are normally expressed in proliferating myeloblasts and suppressed following induction of differentiation. Deregulated and continuous expression of c-myc was shown to block terminal myeloid differentiation at an intermediate stage in the progression from immature blasts to mature macrophages, whereas deregulated and continuous expression of c-myb blocked the terminal differentiation program at the immature myeloblast stage. By manipulating myc function in conditional (differentiation inducible) mutant myeloblastic leukemia cell lines, expressing a chimeric mycer transgene, it was shown that there is a window during myeloid differentiation, after the addition of the differentiation inducer, when the terminal differentiation program switches from being dependent on c-myc suppression to becoming c-myc suppression independent, and where activation of c-myc has no apparent effect on mature macrophages. These myeloblastic leukemia cell lines provide a powerful tool to increase our understanding of the role of c-myc in normal hematopoiesis and in leukemogenesis, while also providing a strategy to clone myc target genes.(ABSTRACT TRUNCATED AT 250 WORDS) Publication Types: Review PMID: 7951003 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 50: Leukemia. 1994 May;8(5):740-8. Signal transduction of steel factor and granulocyte-macrophage colony-stimulating factor: differential regulation of transcription factor and G1 cyclin gene expression, and of proliferation in the human factor-dependent cell line MO7. Hallek M, Ando K, Eder M, Slattery K, Ajchenbaum-Cymbalista F, Griffin JD. Dana-Faber Cancer Institute, Boston, Massachusetts. Steel factor (SF) synergizes with a variety of hemopoietins to support the growth and differentiation of human progenitor cells. The human factor-dependent cell line MO7 has been used as a model to study the interaction of SF with other growth factors such as GM-CSF, because both factors support the proliferation of this cell line and are synergistic in combination. Previous studies have shown that this effect is not readily explained by the synergistic activation of early, cytosolic signal transduction intermediates such as tyrosine kinases, Raf-1, MAP2 kinase, or phospholipase C gamma. In an attempt to further explore the biological and biochemical mechanisms of the synergy between SF and GM-CSF, we examined the effects of these growth factors on the regulation of nuclear proto-oncogenes, cell cycle control genes, and G1-->S transition of MO7 cells. Individually, GM-CSF was a much more potent growth factor for MO7 cells than SF, particularly under serum-free conditions. Only GM-CSF, but not SF, was able to stimulate G1-->S transition of MO7 cells after factor deprivation for 24 h. Northern blot analyses showed also differential effects of GM-CSF and SF on the expression of some nuclear proto-oncogenes and G1 cyclins. GM-CSF (10 ng/ml), but not SF (20 ng/ml) increased the expression of c-myc and cyclin D2 mRNA, whereas both factors caused transient increases of c-fos and cyclin D3 mRNAs. When added simultaneously, GM-CSF and SF induced an at least additive increase of c-fos mRNA expression; this effect required the presence of fetal calf serum. No additive effects of GM-CSF and SF on c-myc, cyclin D2 or D3 mRNA expression were observed. C-jun and c-myb mRNAs were constitutively expressed in the MO7 cell line, but not further increased after stimulation with GM-CSF or SF for 15 min to 48 h. The inability of SF to induce growth promoting genes such as c-myc and cyclin D2 may explain why this cytokine does not support sustained proliferation of MO7 cells. These observations suggest that SF and GM-CSF exert different effects on the expression of genes involved in regulatory pathways of cell proliferation, but the molecular mechanism of synergy remains to be elucidated. PMID: 7514243 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 51: Jpn J Cancer Res. 1994 Apr;85(4):364-71. Proto-oncogene expression in a human chondrosarcoma cell line: HCS-2/8. Zhu JD, Pan HO, Suzuki F, Takigawa M. Chester Beatty Laboratories, London, UK. HCS-2/8 is a stable human chondrosarcoma cell line with many chondrocytic characteristics and has the capacity to form chondrosarcomas in nude mice. The cells display both biochemically and morphologically definable changes in sparse, subconfluent, confluent and over-confluent phases of in vitro culture. Such features of HCS-2/8 cells may reflect the processes of both proliferation and differentiation of chondrocytes in vivo. We examined the correlations of these changes of HCS-2/8 cells with their transcript levels of 21 proto-oncogenes by Northern analysis. We found no detectable transcripts of 9 proto-oncogenes (c-sis, c-met, c-src, c-lyn, c-fgr, c-ros, c-pim, Blym and N-myc), but detected transcripts of 12 other proto-oncogenes (int-2, erbB, c-abl, c-raf-1, c-fyn, K-ras, H-ras, c-mos, c-myc, c-myb, c-fos, and c-jun). In the over-confluent phase, the levels of c-fos and c-raf-1 were increased several dozen times and about 5 times, respectively, while the level of c-abl was about 1/5th of that in the sparse, subconfluent and confluent phases of culture. The level of int-2 increased about 10-fold in the confluent and over-confluent phases of in vitro culture. The transcript levels of c-mos and K-ras were high in the sparse phase, low in the subconfluent and confluent phases and high in the over-confluent phase. The levels of the other 6 proto-oncogenes in HCS-2/8 cells were constant in all phases of in vitro culture. PMID: 8200849 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 52: Int J Cancer. 1994 Apr 1;57(1):98-103. Comparison of retinoic acid and phorbol myristate acetate as inducers of monocytic differentiation. Matikainen S, Hurme M. Department of Bacteriology and Immunology, University of Helsinki, Finland. Several human myeloid leukemia cell lines growing in vitro can be induced to differentiate to more mature monocyte/macrophage-like cells by treatment with protein kinase C-activating phorbol esters, such as PMA. In addition to PMA, cells of the THP-1 myeloid leukemia cell line acquire macrophage-like characteristics after treatment with all-trans retinoic acid (RA). To analyze the signal transduction mechanisms induced by RA, we first compared the effects of PMA and RA on the expression of genes which are known to be regulated during monocytic differentiation. Both RA and PMA effectively down-regulated c-myc expression, while c-myb expression decreased only after PMA treatment. Expression of the beta 2-integrin genes, CD11a and CD11b, was clearly increased after both of these treatments. Their effects on the src-family tyrosine kinase genes were different: hck expression was similarly induced by these agents but lyn expression was stronger and more rapid after RA treatment. RA also enhanced lyn mRNA production rapidly in HL-60, indicating that the activation of lyn gene expression is common in monocytic and granulocytic maturation of myeloid leukemia cells. To examine whether the AP-1 enhancer activity is involved in RA-induced monocytic differentiation, THP-1 cells were transiently transfected with a chloramphenicol acetyl transferase (CAT)-reporter gene containing 5 copies of the AP-1 binding sites. In contrast to PMA, RA did not induce any CAT activity in these cells, thus suggesting that the RA-induced changes in the expression of those genes described above were not dependent on the AP-1 enhancer activity. PMID: 7512079 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 53: Cancer Res. 1994 Jan 15;54(2):592-7. Inhibition by interleukin 4 of leukemia inhibitory factor-, interleukin 6-, and dexamethasone-induced differentiation of mouse myeloid leukemia cells: role of c-myc and junB proto-oncogenes. Kasukabe T, Okabe-Kado J, Hozumi M, Honma Y. Department of Chemotherapy, Saitama Cancer Center Research Institute, Japan. Interleukin 4 (IL-4) inhibited the differentiation of mouse myeloid leukemia M1 cells induced by leukemia inhibitory factor (LIF), interleukin 6, or dexamethasone and conversely enhanced the induction of M1 cell differentiation by 1 alpha,25-dihydroxyvitamin D3. IL-4 blocked LIF-induced differentiation of M1 cells when it was added to the culture medium within 10 h after LIF, but IL-4 did not block differentiation when it was added 12 h after LIF. These results indicate that IL-4 inhibited a critical intermediate step in myeloid leukemia cell differentiation. LIF markedly stimulated the expression of junB mRNA within 2 h but suppressed the expression of c-myb and c-myc after 2- and 12-h treatment, respectively. IL-4 did not significantly affect LIF-induced junB expression or suppression of c-myb expression. However, it interfered significantly with the LIF-induced suppression of c-myc gene expression. Similar results were obtained when interleukin 6 was used to induce differentiation of M1 cells. Dexamethasone and 1 alpha,25-dihydroxyvitamin D3 did not induce junB gene expression but suppressed the expression of c-myb and c-myc. IL-4 also interfered with dexamethasone-induced suppression of c-myc gene expression. On the other hand, IL-4 enhanced 1 alpha,25-dihydroxyvitamin D3-induced down-regulation of c-myc gene expression, consistent with its enhancement of differentiation. These results indicate that the change in c-myc expression induced by IL-4 in M1 cells is closely associated with the effect of IL-4 on the induction of differentiation of M1 cells. PMID: 8275499 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 54: Oncogene. 1994 Jan;9(1):305-11. Detection of proteins that bind to the leucine zipper motif of c-Myb. Favier D, Gonda TJ. Hanson Centre for Cancer Research, Adelaide, South Australia. The product of the c-myb proto-oncogene, c-Myb, binds DNA and can enhance transcription of genes bearing copies of the DNA sequence it recognises. Deletion or disruption of a negative regulatory domain (NRD) in the carboxyl portion of c-Myb results in enhanced transactivating capacity and in parallel, leads to activation of its ability to transform haemopoietic cells. Since mutational analysis has shown that one critical element within the NRD is a leucine zipper motif, we have sought to identify cellular proteins that can interact with the c-Myb leucine zipper. Using fusion proteins containing this region as an affinity reagent, we have identified two nuclear proteins, p67 and p160, that bind to the wild-type, but not to a mutated c-Myb leucine zipper. These two proteins were shown to be related by comparison of peptides generated by partial digestion. While p160 was found to be ubiquitous amongst different murine haemopoietic cell lines, and was also present in NIH3T3 fibroblasts, p67 was detected in a restricted set of immature myeloid cells. Intriguingly p160, but not p67, could also bind to the c-Jun leucine zipper. PMID: 8302594 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 55: Cytotechnology. 1994;16(3):167-78. Ras oncogene enhances the production of a recombinant protein regulated by the cytomegalovirus promoter in BHK-21 cells. Yano T, Teruya K, Shirahata S, Watanabe J, Osada K, Tachibana H, Ohashi H, Kim EH, Murakami H. Laboratory of Cellular Regulation Technology, Graduate School of Genetic Resources Technology, Kyushu University, Fukuoka, Japan. In order to enhance recombinant protein productivity in animal cells, we developed the oncogene activated production (OAP) system. The OAP system is based on the premise that oncogenes are able to enhance promoter activity. To this end, we constructed reported plasmids by fusing various promoters to the human interleukin-6 (hIL-6) cDNA, and the effector plasmids by inserting individual oncogenes, for example c-myc, c-fos, v-jun, v-myb and c-Ha-ras, downstream from the human cytomegalovirus immediate early (CMV) promoter. Results of transient expression experiments with BHK-21 cells suggest that the CMV promoter is the most potent promoter examined and that the ras product is able to transactivate the beta-actin, CMV and SR alpha promoters. Recombinant BHK-21 cells producing hIL-6 under the control of the CMV promoter were contransfected with the ras oncogene and dihydrofolate reductase gene, then selected with 50 nM methotrexate to coamplify the ras oncogene. We were able to rapidly establish a stable and highly productive clone which exhibited a 35-times higher production rate as compared to the control value. PMID: 7766145 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 56: Am J Vet Res. 1993 Dec;54(12):2010-4. Specific expression of cellular oncogenes c-myc and c-myb in T-cell lines established from three types of bovine lymphosarcomas. Ishiguro N, Matsui T, Shinagawa M. Department of Veterinary Public Health, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, Japan. Expression of cellular oncogenes in 3 lymphoid cell lines, BTL-PC3 (BoCD2-, BoCD4-, BoCD8-, BoWC1+), BLS1 (BoCD2+, BoCD4-, BoCD8-, BoWC1+) and BLT2 (BoCD2-, BoCD4-, BoCD8-, BoWC1-), which have been established from calf, skin, and thymic types of lymphosarcomas, respectively, were analyzed by DNA-RNA (northern blot) hybridization. To determine specific expression of oncogenes involved in malignant transformation of the lymphoid cells, cellular RNA was isolated from bovine tumor cell lines, BTL-PC3, BLS1, and BLT2, and from Madin Darby bovine kidney cells used as a control for bovine cell lines. The RNA was hybridized against 5 viral oncogene probes (v-jun, v-myc, v-erbB, v-erbA and v-fes), 6 human cellular oncogene probes (N-ras, c-Blym-1 c-erbB-2, c-fos, c-myb and c-abl), human p53 tumor suppressor gene, and bovine LDH-A gene probes. Line BTL-PC3 expressed 2.4-kilobase (kb) c-myc and 4.0- and 3.6-kb c-myb transcripts, and line BLT2 expressed a 3.8-kb c-myb transcript, but line BLS1 expressed no message for the oncogenes tested. Specific transcripts of p53 were found in BTL-PC3 and BLT2 lines, but not in BLS1. Madin Darby bovine kidney cell line expressed multiple cellular oncogenes, c-jun, c-myc, and c-fos, and p53 genes. Southern blot hybridization did not reveal abnormal DNA rearrangements associated with the expressed oncogenes (c-myc and c-myb) in the 3 bovine tumor lines. (ABSTRACT TRUNCATED AT 250 WORDS) PMID: 8116930 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 57: Oncogene. 1993 Oct;8(10):2713-9. Fos expression induces growth arrest in tumorigenic neuroretina cells. Garrido C, Plaza S, Gospodarowicz D, Saule S. Cancer Research Institute, University of California, Medical Center, San Francisco 94143-0128. E26-infected chicken neuroretina (CNR) cells expressing P135gag-myb-ets are non-transformed and growth can be stimulated by basic fibroblast growth factor (bFGF). In contrast, MHE226-infected CNR cells, which express p61/63myc in addition to the P135gag-myb-ets of E26, are transformed, tumorigenic cells and are growth inhibited by bFGF. We looked for differences in both cells types which could help to understand the molecular basis of the bFGF response. We found marked differences in c-fos expression. In MHE226-CNR cells c-fos mRNA was induced by 12-O-tetradecanoyl phorbol 13-acetate (TPA) and bFGF, both inhibitors of MHE226-infected cell growth. In contrast, serum, a strong growth inducer, did not stimulate c-fos expression. In E26-infected cells all of these factors induced cell growth and c-fos expression. MHE226-CNR cells superinfected with v-fosFBJ-expressing retrovirus were inhibited in their growth and unresponsive to bFGF. Introduction of v-fosFBJ in E26 CNR cells transformed them but they remained sensitive to bFGF. These results suggest that fos is involved in the induced growth arrest of MHE226-CNR cells. PMID: 8397368 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 58: Mol Cell Biol. 1993 Aug;13(8):4609-17. Cooperative DNA binding of the human HoxB5 (Hox-2.1) protein is under redox regulation in vitro. Galang CK, Hauser CA. La Jolla Cancer Research Foundation, California 92037. The human HoxB5 (Hox-2.1) gene product is a sequence-specific DNA binding protein. Cooperative interactions stabilize in vitro DNA binding of the HoxB5 protein to tandem binding sites by at least 100-fold relative to binding to a single site. The HoxB5 homeodomain is sufficient for sequence-specific DNA binding but not for cooperative DNA binding. Here we report that the additional protein sequence required for cooperativity is a small domain adjacent to the homeodomain on the amino-terminal side. We further show that cooperative DNA binding is under redox regulation. The HoxB5 protein binds to DNA in vitro both when oxidized or reduced but binds cooperatively only when oxidized. Mutational analysis has revealed that the cysteine residue in the turn between homeodomain helices 2 and 3 is necessary for cooperative binding and redox regulation. The enhanced DNA binding of oxidized HoxB5 protein is the opposite of the redox regulation reported for other mammalian transcription factors such as Fos, Jun, USF, NF-kappa B, c-Myb, and v-Rel, in which oxidation of cysteine residues inhibits DNA binding. Thus, specific oxidation of nuclear proteins is a potential regulatory mechanism that can act to either decrease or increase their DNA binding activity. PMID: 8101633 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 59: C R Acad Sci III. 1993 Aug;316(8):772-9. Transforming growth factor beta 1-mediated growth inhibition in chick embryo fibroblasts: reversion by virally-expressed nuclear oncogenes. Piu F, Jurdic P, Brun G, Samarut J, Castellazzi M. Laboratoire de Biologie Moleculaire et Cellulaire, Ecole Normale Superieure, UMR 49, CNRS, 46, Lyon, France. Transforming growth factor beta 1 (TGF-beta 1) inhibits growth of primary cultures of chick embryo fibroblasts by affecting G1 and strongly increasing the generation time. This inhibition is reversed by the nuclear oncogenes v-jun, v-fos, v-myc, but not v-erbA and v-ets. It is also reversed by v-myb from either avian myeloblastosis virus or avian E26 retrovirus. Taken together, these results strongly suggest that independent, functional interferences may take place between the TGF-beta 1-induced growth inhibitory pathway and the oncogen-driven stimulatory pathway(s) at the level of the AP-1, Myc, and Myb transcription factors. PMID: 8044700 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 60: Br J Cancer. 1993 Apr;67(4):674-9. Uncoupling of growth inhibition and differentiation in dexamethasone-treated human rhabdomyosarcoma cells. De Giovanni C, Lollini PL, Dolcetti R, Landuzzi L, Nicoletti G, D'Andrea E, Scotland K, Nanni P. Istituto di Cancerologia, University of Bologna, Italy. The effects of dexamethasone, a synthetic glucocorticoid, and of N,N-dimethylformamide on in vitro growth and differentiation and on proto-oncogene expression of human rhabdomyosarcoma cells were studied. RD/18 clone cells (derived from the embryonal rhabdomyosarcoma cell line RD) treated with 100 nM dexamethasone showed an almost complete block of differentiation: about 5% myosin-positive cells were observed after 2 weeks of culture in dexamethasone-supplemented differentiation medium, compared to 20% of untreated cultures. Dexamethasone also induced a 20-30% growth inhibition and a more flattened morphology. The treatment with N,N-dimethylformamide induced a significantly increased proportion of myosin-positive cells (reaching about 30%) and a 40% growth inhibition. Induction of differentiation inversely correlated with the levels of c-myc proto-oncogene expression: after a 2 week culture dexamethasone-treated cells showed the highest c-myc expression and N,N-dimethylformamide-treated cells the lowest. Culture conditions per se down-modulated c-erbB1 and up-regulated c-jun expression, with no relationship to the differentiation pattern. Other proto-oncogenes were not expressed (c-sis, N-myc, c-mos, c-myb) or were not modulated (c-fos, c-raf). Therefore dexamethasone and N,N-dimethylformamide, both causing a decreased growth rate, showed opposing actions on myogenic differentiation and on c-myc proto-oncogene expression of human rhabdomyosarcoma cells. PMID: 8471424 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 61: Curr Probl Cancer. 1993 Mar-Apr;17(2):69-141. Small cell lung cancer: etiology, biology, clinical features, staging, and treatment. Cook RM, Miller YE, Bunn PA Jr. Department of Medicine, University of Colorado Health Sciences Center, Denver. Lung cancer is the leading cause of cancer death in the United States. Small cell lung cancer (SCLC) accounts for 20% to 25% of all bronchogenic carcinoma and is associated with the poorest 5-year survival of all histologic types. SCLC differs in its etiologic, pathologic, biologic, and clinical features from non-SCLC, and these differences have translated to distinct approaches to its prevention and treatment. Compared with other histologic types of lung cancer, exposures to tobacco smoke, ionizing radiation, and chloromethyl ethers pose a substantially greater risk for development of SCLC. The histologic classification of SCLC has been revised to include three categories: (1) small cell carcinoma, (2) mixed small cell/large cell, and (3) combined small cell carcinoma. Ultrastructurally, SCLC displays a number of neuroendocrine features in common with pulmonary neuroendocrine cells, including dense core vesicles or neurosecretory granules. These dense core vesicles are associated with a variety of secretory products, cell surface antigens, and enzymes. The biology of SCLC is complex. The activation of a number of dominant proto-oncogenes and the inactivation of tumor suppressor genes in SCLC have been described. Dominant proto-oncogenes that have been found to be amplified or overexpressed in SCLC include the myc family, c-myb, c-kit, c-jun, and c-src. Altered expression of two tumor suppressor genes in SCLC, p53 and the retinoblastoma gene product, has been demonstrated. Cytogenetic and molecular evidence for chromosomal loss of 3p, 5q, 9p, 11p, 13q, and 17p in SCLC has intensified the search for other tumor suppressor genes with potential import in this malignancy. Bombesin/gastrin-releasing peptide, insulin-like growth factor I, and transferrin have been identified as autocrine growth factors in SCLC, with a number of other peptides under active investigation. Several mechanisms of drug resistance in SCLC have been described, including gene amplification, the recently described overexpression of multi-drug resistance-related protein (MRP), and the expression of P-glycoprotein. The classic SCLC staging system has been supplanted by a revised TNM staging system where limited disease and extensive disease are equivalent to the TNM stages I through III and stage IV, respectively. Therapeutically, recent strategies have attained small improvements in survival but significant reductions in the toxicities of chemotherapeutic regimens. Presently, the overall 5-year survival for SCLC is 5% to 10%, with limited disease associated with a significantly higher survival rate.(ABSTRACT TRUNCATED AT 400 WORDS) Publication Types: Review Review, Tutorial PMID: 8395998 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 62: J Biol Chem. 1993 Feb 25;268(6):4259-66. Isolation and characterization of a novel member of the gene family encoding the cAMP response element-binding protein CRE-BP1. Nomura N, Zu YL, Maekawa T, Tabata S, Akiyama T, Ishii S. Laboratory of Molecular Biology, Nippon Medical School, Kanagawa, Japan. Among multiple CRE (cyclic AMP response element)-binding proteins, CRE-BP1 (also designated ATF-2) has two unique characteristics: it mediates the adenovirus E1A-induced trans-activation and forms a heterodimer with c-Jun. Two structures, a putative metal finger and a leucine zipper, in CRE-BP1 are responsible for these capacities. As a new member of a CRE-BP1 family that has similar metal finger and leucine zipper structures, we have isolated cDNA clones of CRE-BPa by cross-hybridization with CRE-BP1 cDNA. CRE-BPa protein consists of 508 amino acids and has a molecular weight of 56,840. CRE-BPa protein is highly homologous with CRE-BP1 in four regions: two of them are the regions containing the putative metal finger or the DNA-binding domain consisting of the basic amino acid cluster and the leucine zipper. Like CRE-BP1, CRE-BPa binds to CRE with higher affinity than to the 12-O-tetradecanoylphorbol-13-acetate response element as a homodimer or a CRE-BPa/c-Jun or CRE-BPa/CRE-BP1 heterodimer. However, using the c-Myb-CRE-BPa fusion protein, it was show that CRE-BPa could not mediate the E1A-induced trans-activation. Expression of CRE-BPa mRNA was found in a limited number of cell lines, and multiple sizes of CRE-BPa mRNA species were detected in some cell lines and tissues. CRE-BPa will be useful to clarify the mechanism of CRE-mediated transcriptional activation by E1A or c-Jun. PMID: 8440710 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 63: Virology. 1993 Feb;192(2):578-86. v-erbA cooperates with bFGF in neuroretina cell transformation. Garrido C, Li RP, Samarut J, Gospodarowicz D, Saule S. Cancer Research Institute, University of California, San Francisco 94143-0128. We have studied the transforming ability of the oncogenes erbA and/or erbB in chicken neuroretina (CNR) cells and the effect of basic fibroblast growth factor (bFGF) on the transformed phenotype. The erbA oncogene alone was only transforming in the presence of bFGF. In contrast, cells expressing erbB as well as erbA + erbB were transformed in a bFGF-independent manner and were unresponsive to the growth factor. We studied whether other oncogenes could also block the cooperation between erbA and bFGF. Cytoplasmic or membrane-bound oncogenes (src, ras, or mill raf) increased the transforming potential of erbA but rendered the cells unresponsive to bFGF. Conversely, the nuclear oncogenes tested (fos and myb-ets + myc) also cooperated with erbA in CNR cell transformation but the cells remained responsive to the growth factor. A likely explanation is that CNR cells carrying the cytoplasmic but not the nuclear oncogenes have already activated the bFGF signal transduction pathway. PMID: 7678474 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 64: Eur J Biochem. 1993 Jan 15;211(1-2):7-18. Erratum in: Eur J Biochem 1993 Aug 1;215(3):907. The Ets family of transcription factors. Wasylyk B, Hahn SL, Giovane A. CNRS-LGME/INSERM-U. 184, Institut de Chimie Biologique, Faculte de Medecine, Strasbourg, France. Interest in the Ets proteins has grown enormously over the last decade. The v-ets oncogene was originally discovered as part of a fusion protein expressed by a transforming retrovirus (avian E26), and later shown to be transduced from a cellular gene. About 30 related proteins have now been found in species ranging from flies to humans, that resemble the vEts protein in the so-called 'ets domain'. The ets domain has been shown to be a DNA-binding domain, that specifically interacts with sequences containing the common core trinucleotide GGA. Furthermore, it is involved in protein-protein interactions with co-factors that help determine its biological activity. Many of the Ets-related proteins have been shown to be transcription activators, like other nuclear oncoproteins and anti-oncoproteins (Jun, Fos, Myb, Myc, Rel, p53, etc.). However, Ets-like proteins may have other functions, such as in DNA replication and a general role in transcription activation. Ets proteins have been implicated in regulation of gene expression during a variety of biological processes, including growth control, transformation, T-cell activation, and developmental programs in many organisms. Signals regulating cell growth are transmitted from outside the cell to the nucleus by growth factors and their receptors. G-proteins, kinases and transcription factors. We will discuss how several Ets-related proteins fit into this scheme, and how their activity is regulated both post- and pre-translationally. Loss of normal control is often associated with conversion to an oncoprotein. vEts has been shown to have different properties from its progenitor, which might explain how it has become oncogenic. Oncogene-related products have been implicated in the control of various developmental processes. Evidence is accumulating for a role for Ets family members in Drosophila development, Xenopus oocyte maturation, lymphocyte differentiation, and viral infectious cycles. An ultimate hope in studying transformation by oncoproteins is to understand how cells become cancerous in humans, which would lead to more effective treatments. vEts induces erythroblastosis in chicken. Cellular Ets-family proteins can be activated by proviral insertion in mice and, most interestingly, by chromosome translocation in humans. We are at the beginning of understanding the multiple facets of regulation of Ets activity. Future work on the Ets family promises to provide important insights into both normal control of growth and differentiation, and deregulation in illness. Publication Types: Review PMID: 8425553 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 65: Proc Natl Acad Sci U S A. 1993 Jan 15;90(2):477-81. Induction of protein-tyrosine-phosphatase activity by interleukin 6 in M1 myeloblastic cells and analysis of possible counteractions by the BCR-ABL oncogene. Zafriri D, Argaman M, Canaani E, Kimchi A. Department of Molecular Genetics and Virology, Weizmann Institute of Science, Rehovot, Israel. Interleukin 6 (IL-6) induces in M1 myeloblastic cells growth arrest and terminal differentiation toward monocytes. It is reported here that IL-6 reduced by 5- to 20-fold the tyrosine phosphorylation of cellular proteins in these cells. The same-fold reduction was also observed in M1 cells that were transfected with the BCR-ABL deregulated protein kinase. In these stable clones, the levels of tyrosine phosphorylation of cellular proteins were 30- to 100-fold higher than in the parental cells. IL-6 did not reduce the expression levels or the inherent tyrosine kinase activity of BCR-ABL p210. By measuring the protein-tyrosine-phosphatase (PTPase; protein-tyrosine-phosphate phosphohydrolase, EC 3.1.3.48) activity in crude cell lysates, we found that protein dephosphorylation resulted, at least partially, from induction of PTPase activity by IL-6. The induction of PTPase in the BCR-ABL-transfected clones was not sufficient to confer the minimal protein phosphorylation levels characteristic of IL-6-treated cells. Yet, the transfected M1 clones showed normal growth and differentiation responses to IL-6. None of the gene responses to IL-6 including suppression in the levels of c-myc, c-myb, and cyclin A mRNA; junB and c-jun mRNA induction; and dephosphorylation of retinoblastoma protein were rescued by the BCR-ABL oncogene. The functional relevance of PTPase induction by IL-6 is discussed. PMID: 8421678 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 66: Biochem J. 1992 Oct 1;287 ( Pt 1):1-15. Nuclear protein phosphorylation and growth control. Meek DW, Street AJ. Department of Biochemistry, University of Dundee, Scotland, U.K. Publication Types: Review PMID: 1417761 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 67: Proc Natl Acad Sci U S A. 1992 Oct 1;89(19):9210-4. Growth arrest induced by wild-type p53 protein blocks cells prior to or near the restriction point in late G1 phase. Lin D, Shields MT, Ullrich SJ, Appella E, Mercer WE. Department of Microbiology and Immunology, Jefferson Cancer Institute, Thomas Jefferson University, Philadelphia, PA 19107. Conditional expression of wild-type (wt) p53 protein in a glioblastoma tumor cell line has been shown to be growth inhibitory. We have now more precisely localized the position in the cell cycle where growth arrest occurs. We show that growth arrest occurs prior to or near the restriction point in late G1 phase of the cell cycle. The effect of wt p53 protein on the expression of four immediate-early genes (c-FOS, c-JUN, JUN-B, and c-MYC), one delayed-early gene (ornithine decarboxylase), and two late-G1/S-phase genes (B-MYB and DNA polymerase alpha) was also examined. Of this subset of growth response genes, only the expression of B-MYB and DNA polymerase alpha was significantly repressed. The possibility that decreased expression of B-MYB may be an important component of growth arrest mediated by wt p53 protein is discussed. PMID: 1409626 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 68: J Biol Chem. 1992 Sep 25;267(27):19665-72. The Jun family members, c-Jun and JunD, transactivate the human c-myb promoter via an Ap1-like element. Nicolaides NC, Correa I, Casadevall C, Travali S, Soprano KJ, Calabretta B. Jefferson Cancer Institute, Thomas Jefferson University, Philadelphia, Pennsylvania 19140. The c-myb protooncogene, which is preferentially expressed in hematopoietic cells at the G1/S boundary of the cell cycle, encodes a transcriptional activator that functions via DNA binding. The regulatory mechanisms governing this specific pattern of expression are not fully understood, although human c-myb expression appears to be positively autoregulated via myb-binding sites in the 5'-flanking region of the c-myb gene (Nicolaides, N. C., Gualdi, R., Casadevall, C., Manzella, L., and Calabretta, B. (1991) Mol. Cell. Biol. 11, 6166-6176). To determine the contribution of other transcription regulators such as JUN family members in the control of c-myb expression, transient expression assays were carried out which revealed a 6- to a 15-fold enhancement by c-Jun and JunD, but not JunB, in chloramphenicol acetyltransferase reporter gene expression driven by different segments of the human c-myb 5'-flanking region. An Ap1-like element located at nucleotide -149 from the c-myb initiation site appears to be required for this transactivation upon binding to a nuclear protein complex containing c-Jun and JunD, since site-directed mutations of this Ap1-like element abolished c-Jun and JunD binding and transactivation. Exposure of phytohemagglutinin-stimulated peripheral blood mononuclear cells to c-jun and junD antisense oligodeoxynucleotides resulted in a 46 and 43% inhibition of T-lymphocyte proliferation that was accompanied by a decrease in c-myb mRNA levels as compared with sense-treated cultures. Because T-lymphocytes induced to proliferate express c-jun and junD before c-myb, these data suggest a mechanism whereby c-Jun and JunD contribute to the transcriptional activation of c-myb that, in turn, is maintained at the G1/S transition and during S phase by positive autoregulation. PMID: 1527086 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 69: EMBO J. 1992 Sep;11(9):3323-35. Redox activation of Fos-Jun DNA binding activity is mediated by a DNA repair enzyme. Xanthoudakis S, Miao G, Wang F, Pan YC, Curran T. Department of Molecular Oncology and Virology, Roche Institute of Molecular Biology, New York, NY. The DNA binding activity of Fos and Jun is regulated in vitro by a post-translational mechanism involving reduction-oxidation. Redox regulation occurs through a conserved cysteine residue located in the DNA binding domain of Fos and Jun. Reduction of this residue by chemical reducing agents or by a ubiquitous nuclear redox factor (Ref-1) recently purified from Hela cells, stimulates AP-1 DNA binding activity in vitro, whereas oxidation or chemical modification of the cysteine has an inhibitory effect on DNA binding activity. Here we demonstrate that the protein product of the ref-1 gene stimulates the DNA binding activity of Fos-Jun heterodimers, Jun-Jun homodimers and Hela cell AP-1 proteins as well as that of several other transcription factors including NF-kappa B, Myb and members of the ATF/CREB family. Furthermore, immunodepletion analysis indicates that Ref-1 is the major AP-1 redox activity in Hela nuclear extracts. Interestingly, Ref-1 is a bifunctional protein; it also possesses an apurinic/apyrimidinic (AP) endonuclease DNA repair activity. However, the redox and DNA repair activities of Ref-1 can, in part, be distinguished biochemically. This study suggests a novel link between transcription factor regulation, oxidative signalling and DNA repair processes in higher eukaryotes. PMID: 1380454 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 70: J Biol Chem. 1992 Apr 25;267(12):8222-9. Stable expression of HB24, a diverged human homeobox gene, in T lymphocytes induces genes involved in T cell activation and growth. Deguchi Y, Thevenin C, Kehrl JH. Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20892. A diverged homeobox gene, HB24, which is known to be induced following lymphocyte activation, was introduced into Jurkat T cells under the control of a constitutive promoter. Stable transfectants of HB24 were established that expressed high levels of HB24 mRNA and possessed an altered phenotype suggestive of activated T cells. A number of genes known to be induced following T cell activation and associated with cell growth were increased in the transfectants, including c-fos, c-myc, c-myb, HLA-DR, lck, NF-kappa B, interleukin-2 and interleukin-2 receptor alpha (IL-2R alpha). Analysis of IL-2R alpha expression by transient transfection of IL-2R alpha promoter constructs into the HB24 transfectants revealed constitutive expression (about 60% of phytohemagglutinin- and phorbol ester-activated Jurkat cells) that was dependent on the kappa B site in the IL-2R alpha promoter. Furthermore, as a consequence of the increased HB24 mRNA levels, the Jurkat HB24 transfectants proliferated more rapidly than control cell lines. Thus, stable expression of HB24 confers an activation phenotype on a human T cell line, implicating this gene as an important transcriptional factor during T cell activation and growth. PMID: 1349016 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 71: Rinsho Ketsueki. 1992 Apr;33(4):467-72. [A case report of AML M0:CD7, 33 (+) AML M0 case initially presented with cervical lymphadenopathy] [Article in Japanese] Horiguchi J, Yamamura S, Nemoto T, Fujikawa T, Inaba S, Yamazaki Y, Yamada H. Department of Internal Medicine, Aoto Hospital, Jikei University, School of Medicine. A 59-year-old man was admitted because of generalized lymphadenopathy with fever and vomiting. His peripheral blood showed leukocytosis with a WBC of 93,500/microliters, and the bone marrow picture revealed a predominance of blast cells. The blasts were negative for peroxidase, alpha-naphthyl butyrate esterase and PAS, and had the phenotype of CD 7, 13 and 33 positive. A diagnosis of AML M0 was made, based on the criteria of the NCI-sponsored workshop in 1988. His initial status had been compromised by acute renal failure which necessitated hemodialysis. He responded partially to chemotherapy consisting of daunorubicin, cytarabine and prednisolone. However leukemia recurred and the patient suffered from various episodes of infection and died six months after admission. The Southern blotting showed the germ line configuration for TCR-beta chain and immunoglobulin heavy chain genes. No messenger RNA was detected for myeloperoxidase, c-myc and c-jun, while c-fms, c-fos and c-myb were expressed on Northern blotting. It is intriguing to detect c-fms and c-fos expression in these poorly differentiated leukemic cells. Publication Types: Case Reports PMID: 1602610 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 72: Proc Natl Acad Sci U S A. 1992 Feb 15;89(4):1291-5. Myb and Ets proteins cooperate in transcriptional activation of the mim-1 promoter. Dudek H, Tantravahi RV, Rao VN, Reddy ES, Reddy EP. Wistar Institute of Anatomy and Biology, Philadelphia, PA 19104. In the generation of the acutely transforming avian retrovirus E26, both myb and ets genes have been transduced, leading to the production of a Gag-Myb-Ets fusion protein. This co-occurrence of v-myb and v-ets oncogenes suggests that the two might have a functional relationship. To look for such a relationship, we tested the transcriptional activation activity of Myb alone or with coexpressed Ets-1 or Ets-2. Using the promoter of the v-Myb-inducible mim-1 gene as a target, we found that full-length c-Myb gene products were poor activators of transcription, while an oncogenic (truncated) form of this protein was a strong trans-activator. However, coexpression of Ets-2 with full-length or truncated forms of Myb greatly increased trans-activation. Coexpression of Ets-1, Fos, Jun, or Myc with Myb did not increase trans-activation of the mim-1 promoter. The ability of Myb and Ets-2 to transactivate was cooperative, since Ets-2 alone gave little or no activation. Bacterially synthesized Ets-2 protein was found to bind specifically to the mim-1 promoter, suggesting that it may be a target for both Myb and Ets proteins. Thus, Myb and Ets proteins can cooperate in transcriptional activation, and their co-occurrence in the E26 virus may reflect a functional relationship between these two oncoproteins. Truncated forms of Myb may have a reduced need for cooperating factors such as Ets-2, and this might constitute an important mechanism associated with oncogenic activation. PMID: 1741383 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 73: Crit Rev Eukaryot Gene Expr. 1992;2(3):225-35. c-myb and growth control. Calabretta B, Nicolaides NC. Department of Microbiology, Jefferson Cancer Institute, Thomas Jefferson University, Philadelphia, PA 19107. The available evidence indicates that c-myb plays an important role in the proliferation of hematopoietic cells and in those nonhematopoietic cell types in which c-myb is expressed. A critical aspect in the regulation of c-myb expression rests in the positive autoregulatory mechanism, which is dependent on the interaction of myb protein with the 5' flanking region of the human c-myb gene. The positive autoregulation of c-myb, in conjunction with tissue-specific mechanisms that most likely involve efficient transcription beyond the site of "transcriptional pause" in the c-myb first intron, might allow the generation of c-myb transcripts at levels sufficiently high for optimal biological activity (e.g., at the G1/S transition of the cell cycle). Other transactivating factors, such as the Jun family members, also appear to be involved in regulating c-myb expression. Such factors might act to increase basal levels of c-myb expression to allow activation of the autoregulatory mechanism, or might cooperate with myb in transcriptional regulation of c-myb expression. The function of c-myb is ultimately dependent on the genes that are regulated by the myb product. Preliminary evidence suggests that DNA polymerase-alpha and cdc2, two genes that are critical for DNA synthesis, contain myb binding sites in their promoter region that appear to be required for myb transactivation of their expression. The paradox of the generality of the mechanisms by which c-myb affects cell proliferation and the apparent tissue-specific expression of this gene might be resolved by the growing evidence that the tissue distribution of c-myb is more general than previously appreciated, and that many cell types with no detectable c-myb expression contain a functional equivalent of this gene. For example, B-myb a gene that is homologous to c-myb in the DNA binding and transactivating domains and appears to be ubiquitously expressed, is also required for cell proliferation and, like c-myb, appears to regulate the expression of cdc2, a gene required for cell cycle progression. Together, these findings indicate a general role of members of the myb family in regulation of cell proliferation. Publication Types: Review Review, Tutorial PMID: 1511186 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 74: Oncol Res. 1992;4(7):291-8. HL-60 cells isolated for resistance to vincristine are defective in 12-O-tetradecanoylphorbol-13-acetate induced differentiation and the formation of a functional AP-1 complex. Ma L, Krishnamachary N, Perbal B, Center MS. Division of Biology, Kansas State University, Manhattan 66506. HL-60 cells isolated for resistance to vincristine are multidrug resistant and defective in the cellular accumulation of drug. Further studies demonstrate that these cells are also highly defective in 12-O-tetradecanoylphorbol-13-acetate (TPA) induced differentiation to macrophages. Analysis of this system demonstrates that certain protooncogenes which may contribute to differentiation are expressed at similar levels in sensitive and resistant cells. Thus, treatment of cells with TPA results in a reduction in the levels of c-myb and c-myc mRNA, while the expression of c-fos, c-jun, and junB is greatly enhanced. Immunoprecipitation experiments also demonstrate a TPA induced increase in the c-jun protein in both sensitive and resistant cells. Gel mobility shift assays show that TPA induces AP-1 formation in sensitive cells, whereas in parallel experiments with the HL-60/Vinc isolate, AP-1 is essentially absent. It has been found, however, that in resistant cells which have reverted to drug sensitivity, the levels of TPA inducible AP-1 is essentially identical to that of sensitive cells. Revertant and sensitive cells differentiate at similar levels in the presence of TPA. These studies therefore demonstrate that HL-60/Vinc cells are defective in the TPA induction of a functional AP-1 complex and that this may account for the inability of these cells to differentiate to macrophages. The molecular basis of the finding that AP-1 is not formed in resistant cells remains to be determined. PMID: 1450490 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 75: EMBO J. 1992 Jan;11(1):115-26. Autocrine growth induced by kinase type oncogenes in myeloid cells requires AP-1 and NF-M, a myeloid specific, C/EBP-like factor. Sterneck E, Muller C, Katz S, Leutz A. Zentrum fur Molekulare Biologie Heidelberg, University of Heidelberg, FRG. The nuclear oncogenes v-myc or v-myb specifically transform avian myeloid cells. In both cases, the transformed cells remain dependent on chicken myelomonocytic growth factor (cMGF). This factor dependence can be relieved by expression of kinase-type oncogenes such as v-mil or v-erbB, leading to expression of cMGF and autocrine growth stimulation. In erythroid cells the same kinase-type oncogenes cause transformation but do not induce cMGF expression. Here we investigated the molecular mechanisms of the observed lineage specific oncogene collaboration. We found that kinase-type oncogenes and TPA activate the cMGF promoter via AP-1 like transcription factors. The activation of the cMGF promoter is, however, strictly dependent on the binding of nuclear proteins to both halves of an inverted repeat adjacent to the AP-1 binding site. These proteins are related to C/EBP. They are expressed exclusively in myeloid cells and were therefore termed NF-M. Our results indicate that the lineage specific cooperation of kinase type oncogenes with v-myb or v-myc in leukemia formation is based on the concerted action of AP-1 and NF-M on the cMGF promoter. PMID: 1346759 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 76: Oncogene. 1991 Nov;6(11):2129-35. v-erbA oncogene abrogates growth inhibition of chicken embryo fibroblasts induced by retinoic acid. Desbois C, Pain B, Guilhot C, Benchaibi M, Ffrench M, Ghysdael J, Madjar JJ, Samarut J. Immuno-Virologie Moleculaire et Cellulaire, Universite Claude Bernard Lyon-1/CNRS UMR 30, Faculte de Medecine Alexis Carrel, Lyon, France. Retinoic acid inhibits chicken embryo fibroblast (CEF) proliferation by altering the G1 phase of the cell cycle with induction of a strong increase in the generation time. This growth-inhibitory response to retinoic acid is abrogated by expression of the v-erbA oncogene, suggesting an interference between retinoic acid receptors and the v-ErbA oncoprotein. Moreover, CEF expressing either the v-src, v-jun or v-fos oncogenes are also insensitive to retinoic acid treatment. In contrast, CEF expressing either the v-myc, v-myb-ets, v-mil, v-sea or v-erbB oncogenes are still sensitive to retinoic acid. These data strongly suggest functional interferences between the retinoic acid receptors and the AP-1 transcription factor complex in the control of expression of genes involved in CEF proliferation. PMID: 1682867 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 77: Rinsho Ketsueki. 1991 Sep;32(9):986-90. [Altered expression of protooncogenes during clinical course in an AML case transformed from MDS] [Article in Japanese] Fujikawa T, Horiguchi J, Iizuka K, Nemoto T, Iwase S, Yamamura S, Inaba S, Yamazaki Y, Sano S, Yamada H. Department of Internal Medicine, Aoto Hospital, Jikei University School of Medicine. The changes of expression of oncogenes in the mononuclear cells of MDS case was studied during his clinical course, in series. His bone marrow was considered to maintain its function partly in initial stage, since both peripheral blood and bone marrow responded to clinical episodes. However, his hematopoietic function was gradually impaired with the disease evolution to AML. We examined the expression of four oncogenes in the mononuclear cells of his three clinical stages, early RAEB-t, RAEB-t and AML, to study the cause of transformation from MDS to AML. Early RAEB-t cells expressed all oncogenes studied other than c-myb, while only c-myc was weakly observed in RAEB-t. AML cells expressed c-myc, c-jun and c-myb, except for c-fms. The expression of c-fms and c-jun of early RAEB-t was considered to reflect the monocytosis induced by infections, and the expressions of c-myb and c-myc of AML cells were regarded as one of malignant signs of tumor transformation. These findings suggest that the evolutional transformation of MDS to AML was affected by the altered expression of oncogenes. Publication Types: Case Reports PMID: 1942545 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 78: Kidney Int. 1991 May;39(5):946-53. Proto-oncogene expression in peripheral blood mononuclear cells in IgA nephropathy. Ebihara I, Nakamura T, Suzuki S, Tomino Y, Koide H. Department of Medicine, Juntendo University School of Medicine, Tokyo, Japan. We have investigated the expression of proto-oncogenes in mononuclear cells obtained from patients with IgA nephropathy using a RNA hybridization technique. Patients with IgA nephropathy expressed more c-myc, c-raf, c-fos, and c-jun proto-oncogene RNA than did normal controls. However, no significant expression of c-N-ras, c-mos or c-myb genes was found in the mononuclear cells of these patients. When the amount of urinary protein excretion was used as an indicator of disease activity (greater than 1 g/day), a positive correlation was found between c-myc, c-raf, c-fos, and c-jun expression and urinary protein excretion (P less than 0.01). The expression of these genes correlated also with the serum IgA concentration (P less than 0.01), IgA immune complex (P less than 0.01), and histopathological changes in renal tissues obtained from patients with IgA nephropathy (P less than 0.01). The results of this survey suggest that abnormally regulated proto-oncogene expression in mononuclear cells may play an important role in the progression of IgA nephropathy and may be useful as an indicator of disease activity and/or prognosis. PMID: 1712408 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 79: Trends Biochem Sci. 1991 May;16(5):177-81. A common denominator linking glycogen metabolism, nuclear oncogenes and development. Woodgett JR. Ludwig Institute for Cancer Research, London, UK. A ubiquitous protein-serine kinase, initially implicated in glycogen regulation, has surfaced unexpectedly in the fields of nuclear oncogenes and fruitfly development. This unusual linkage may reflect the role of this kinase in phosphorylating proteins normally activated by dephosphorylation, thus providing a priming function. Loss of such a primer would result in constitutive activation of substrates, a scenario concordant with the dramatic and pleiotropic phenotype observed in Drosophila null mutants. Publication Types: Review Review, Tutorial PMID: 1652801 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 80: Oncogene. 1991 Mar;6(3):455-60. Phorbol ester-mediated inhibition of growth and regulation of proto-oncogene expression in the human T cell leukemia line JURKAT. Makover D, Cuddy M, Yum S, Bradley K, Alpers J, Sukhatme V, Reed JC. Department of Internal Medicine, University of Pennsylvania, Philadelphia 19104. The expression and function of several proto-oncogenes were examined in a human acute T cell leukemia line, JURKAT, during phorbol ester-induced terminal differentiation. Treating JURKAT cells with the phorbol ester tetradecanoyl phorbol acetate (TPA) inhibited their proliferation and induced expression of the gene for the interleukin 2 receptor alpha chain (IL2R-alpha), consistent with previous reports. In unstimulated proliferating JURKAT cells, high levels of C-MYC, N-RAS, and BCL2 mRNAs were found that diminished rapidly following TPA-induced cessation of growth. In contrast, accumulation of mRNAs for the C-FOS, C-JUN, and EGR-1 genes increased markedly in TPA-treated cells and preceded the induction of IL2R-alpha mRNA. Expression of C-MYB, C-RAF-1, C-LCK, C-FYN, and C-FGR proto-oncogenes was relatively unchanged. To explore directly the function of two of these protooncogenes in regulating the growth of JURKAT T cells, we stably transferred C-MYC and BCL2 expression plasmids into these cells. Despite sustained expression of C-MYC, BCL2, or the combination of these protooncogenes, TPA continued to inhibit JURKAT cell growth and to induce IL2R expression. Thus, although C-MYC and BCL2 proto-oncogene expression correlated with proliferation in TPA-treated JURKAT cells, continuous over-expression of even the combination of these oncogenes was insufficient for abrogating the effects of TPA in these leukemic T cells. Because human lymphoid malignancies frequently contain chromosomal translocations that deregulate the expression of C-MYC and BCL2, our findings could have relevance for attempts to induce terminal differentiation of leukemic cells by in vitro exposure of patients' bone marrow cells to phorbol esters. PMID: 2011401 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 81: Leukemia. 1991 Feb;5(2):142-9. Childhood undifferentiated leukemia with early erythroid markers and c-myb duplication. Castaneda VL, Parmley RT, Saldivar VA, Cheah MS. Department of Pediatrics, University of Texas Health Science Center, San Antonio 78284-7810. Ultrastructural, flow cytometric, and molecular studies were performed on leukemia cells from bone marrow and pleural effusion of a 6-year-old boy diagnosed with undifferentiated (MO) leukemia, using routine histology and immunostains at diagnosis and relapse. Ultrastructurally, surface and/or intracellular ferritin particles were present on or in some blasts and the majority of blasts contained identifiable acid ferrocyanide reactive inorganic iron comparable to that seen in normal early erythroblasts. The cells lacked other evidence of differentiation, including diaminobenzidine-reactive or immunoreactive hemoglobin. Flow cytometric analysis of malignant cells showed a lack of lymphoid or myeloid markers. Anti-transferrin receptor antibody was positive on 93% of cells and antibody to glycophorin A reacted with 23% of cells. RNA blot analysis of leukemia cells with myeloperoxidase (MPO) showed an absence of appreciable levels of MPO mRNA. Chromosome analysis showed 51,XY, t(1;16)(p31;q24), +6, +10, +15, +19, +21. The oncogene c-myb, which is specifically expressed and regulated in hematopoietic cells and produces a DNA-binding protein responsible for myeloid differentiation, was found to be duplicated in the patient's tumor cells. Expression of c-jun, N-ras, c-myc, and p53 was normal. The data indicate that the malignant cells in this patient are of early erythroid lineage at diagnosis and relapse and that classification of cell lineage can be enhanced by ultrastructural Prussian blue staining. The failure of this otherwise undifferentiated leukemia to express or evolve into a myeloid phenotype is biologically and clinically distinct from previously described cases of erythroid and myeloid leukemia and may represent a previously unidentified phenotype which should be included in the spectrum of 'undifferentiated' childhood leukemia. Publication Types: Case Reports PMID: 1708434 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 82: Mol Carcinog. 1991;4(4):297-307. Isolation and partial characterization of a transformation-associated sequence from human nasopharyngeal carcinoma. Cao Y, Sun Y, Poirier S, Winterstein D, Hegamyer G, Seed J, Malin S, Colburn NH. Laboratory of Viral Carcinogenesis, National Cancer Institute, Frederick Cancer Research, Maryland 21702-1201. A transforming activity associated with Chinese nasopharyngeal carcinoma (NPC) cell line CNE2 DNA has been identified by transfer into nontransformed promotion-sensitive mouse JB6(P+) C141 cells. To clone this transformation-associated sequence, we carried out three cycles of transfection, followed by cloning of anchorage-independent transformants in soft agar. A tertiary CNE/JB6 clonal transfectant cell line 625 whose DNA showed transforming activity, as indicated in both soft-agar assay and nude-mice implantation, was used to make a genomic library in the vector lambda dash. Using the human repeated sequence Blur 8 to screen the library, we obtained 10 human Alu-positive clones. A cloned Alu-positive insert of 16 kbp, CNE 323, was characterized in detail. CNE 323 transferred moderate transforming activity when introduced into JB6 P+ cells and showed no homology to Ha-, Ki-, or N-ras genes; human promotion sensitivity genes; src, myb, jun, myc, fos, raf, or int-2 oncogenes; or epidermal growth factor receptor. The isolated CNE 323 DNA sequence appeared to preserve the genomic structure of the original sequence found in CNE2 cells and in nude mouse tumors induced by CNE2 cells or by CNE/JB6 transfectant cells, indicating that the cloned NPC sequence was activated during NPC carcinogenesis and not during transfection or construction of the library, and that the cloned sequence or a larger sequence of which it was part played a role in tumor formation. Finally, we identified a 1.3-kb mRNA that hybridizes to a subclone of the 16-kb NPC sequence in CNE2 cell poly (A)+ RNA. PMID: 1714741 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 83: Am Rev Respir Dis. 1990 Dec;142(6 Pt 2):S20-6. Gene amplification in human lung cancer. The myc family genes and other proto-oncogenes and growth factor genes. Bergh JC. Department of Oncology, University of Uppsala, Sweden. The development of human lung cancer may require multiple genetic deletions affecting a number of chromosomes, e.g., 1, 3, 11, 13, and 17. These genetic aberrations may induce the activation of proto-oncogenes (c-jun, ras, c-raf1) and the loss of tumor suppressor genes (p53). Some of the activated proto-oncogenes and tumor suppressor genes are more selectively expressed or absent in small-cell lung cancer (L-myc, c-myb, c-scr, Rb gene) or non-small-cell lung cancer (c-erbB-2, c-sis, c-fes). These genes may thus be of importance for selection of differentiation pathway. The c-myc oncogene is frequently amplified in small-cell lung cancer cell lines in a much higher frequency than in vivo. This indicates that c-myc seems to be related to tumor progression and a relatively late event in the lung cancer development. The uncontrolled production of multiple growth factors has been identified in human lung cancer cell lines. These factors can promote and inhibit the proliferation via paracrine and autocrine loops via specific receptors. The products from some of the activated proto-oncogenes (c-sis, c-erbB-2) are sequences homologous to a certain growth factor (PDGF) and a receptor (EGF) identified in lung cancer. The production and action of these growth factors may be of major importance for further activation of proto-oncogenes via intracellular signal transduction and specific oncogenic activation leading to further tumor progression. Publication Types: Review Review, Tutorial PMID: 2174659 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 84: Cancer Cells. 1990 Nov;2(11):337-44. Transcription factor phosphorylation: a link between signal transduction and the regulation of gene expression. Bohmann D. European Molecular Biology Laboratory, Differentiation Programme, Heidelberg, FRG. Changes in cellular gene transcription patterns induced by extracellular signals are thought to be important for many biological processes, including the control of cell growth. The transmission of gene regulatory signals through the cytoplasm is mediated by signaling pathways, of which protein kinases are important components, and recent evidence suggests that communication between the cytoplasm and nucleus relies on signal-dependent phosphorylation and dephosphorylation of transcription factors. This new information is reviewed and the implications for gene regulation and the control of cell growth are discussed. Publication Types: Review Review, Tutorial PMID: 2149275 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 85: Blood. 1990 Nov 1;76(9):1830-7. Amplified expression of three jun family members inhibits erythroleukemia differentiation. Prochownik EV, Smith MJ, Snyder K, Emeagwali D. Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor. Several different proto-oncogenes have been shown to influence cellular differentiation. One of the most widely studied model systems has been the Friend murine erythroleukemia cell (F-MELC) line, which can be induced to undergo erythroid differentiation by a variety of chemical agents. Constitutive overexpression of either the c-myc or c-myb proto-oncogenes has been previously shown to inhibit F-MELC differentiation, whereas c-myc antisense sequences accelerate the process. To investigate the potential involvement of other proto-oncogenes and immediate early response genes in F-MELC differentiation, we studied the expression of the three known members of the jun family as well as another gene, egr-1, which, like the jun family members, is expressed as an immediate early response gene in growth factor-stimulated quiescent cells. All four genes were expressed in F-MELC, although the levels of expression and modes of regulation differed. Transfection with amplifiable c-jun, junB, or junD expression plasmids inhibited differentiation, whereas transfection with an egr-1 expression plasmid was without effect. These results indicate that jun family members play a role in mediating F-MELC differentiation. The known inhibitory effect of phorbol ester tumor promoters on F-MELC differentiation may be the result of their known stimulation of jun expression. PMID: 2121297 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 86: Cell Growth Differ. 1990 Mar;1(3):113-7. Transcriptional down-regulation of c-myc expression by protein synthesis-dependent and -independent pathways in a human T lymphoblastic tumor cell line. Bading H, Moelling K. Max-Planck-Institut fuer Molekulare Genetik, Berlin, Federal Republic of Germany. We show that in the human T lymphoblastic tumor cell line Molt4 c-myc mRNA and protein expression is down-regulated after exposure to dimethyl sulfoxide, to phorbol myristate acetate, or to the calcium ionophore A23187, which raises the intracellular calcium concentration. A block to RNA elongation is largely responsible for decreased c-myc transcription. Although negative regulation by dimethyl sulfoxide takes place even when protein synthesis is inhibited by cycloheximide, the phorbol myristate acetate effect is blocked to some extent only by cycloheximide. The calcium ionophore-induced c-myc suppression, however, strictly requires de novo protein synthesis. Therefore, two different negative regulatory pathways are involved in c-myc regulation: one which is independent and one which depends on de novo protein synthesis. The latter one appears to be mediated by a rapidly calcium-dependent induced gene product. PMID: 2127692 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 87: Oncogene. 1990 Jan;5(1):85-95. Charge configurations in oncogene products and transforming proteins. Karlin S, Brendel V. Department of Mathematics, Stanford University, California 94305. Statistically significant charge clusters are of infrequent occurrence in all kinds of proteins. In the six standard classes of proto-oncogene products, all of the nuclear class contain a significant charge cluster and several, but not all, of the transmembrane class do, whereas significant charge clusters or patterns are not found in protooncogenes of primarily cytoplasmic location, nor in membrane-bound (src-like) proto-oncogenes, nor in those of the ras family. Among nuclear oncogene families, such as myc, jun, fos, myb, or ets-related, and among homologous proteins across species, the significant charge clusters are part of the most conserved region. These gene families generally have similar charge distributions embodying a significant charge cluster, not of an invariant sign, preceded by a substantial uncharged stretch of predominantly polar residues. The nuclear transforming proteins p53 and p68 also contain significant charge clusters together with long uncharged segments, suggestive of a modular structure of these proteins. The transmembrane oncogene c-mas contains a mixed charge cluster and c-fms displays an unusual (0, +)7 pattern, in both cases positioned within their intracellular activating domain. Distinctive charge configurations for excreted proto-oncogenes are of a mixed character. Possible functions, mechanisms, and associated experimental procedures for studying proteins with anomalous charge distributions are discussed. PMID: 2181379 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 88: Science. 1989 Nov 17;246(4932):931-5. BAS1 has a Myb motif and activates HIS4 transcription only in combination with BAS2. Tice-Baldwin K, Fink GR, Arndt KT. Cold Spring Harbor Laboratory, NY 11724. The BAS1 and BAS2 proteins are both required for activation of GCN4-independent (basal) HIS4 transcription in yeast. BAS1 has an NH2-terminal region similar to those of the myb proto-oncogene family. BAS1 and BAS2, which contains a homeo box, bound to adjacent sites on the HIS4 promoter. The joint requirement of BAS1 and BAS2 for activation is probably not due to cooperative binding or the transcriptional control of one of the genes by the other. Although BAS1 and BAS2 were both required for activation of HIS4 transcription, BAS1 was not required for BAS2-dependent expression of the secreted acid phosphatases. The transcriptional activators of HIS4 have DNA binding domains that are conserved in evolution (BAS1 = Myb, BAS2 = homeo box, GCN4 = Jun). Their interactions, therefore, may be relevant to the control of gene expression in more complex systems. PMID: 2683089 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 89: J Virol. 1989 Aug;63(8):3220-6. Activation of endogenous c-fos proto-oncogene expression by human T-cell leukemia virus type I-encoded p40tax protein in the human T-cell line, Jurkat. Nagata K, Ohtani K, Nakamura M, Sugamura K. Department of Microbiology, Tohoku University School of Medicine, Sendai, Japan. We examined the ability of the trans-acting factor p40tax of human T-cell leukemia virus type I (HTLV-I), which is thought to be a crucial molecule in T-cell transformation by HTLV-I, to activate expression of a set of endogenous cellular genes related to T-cell proliferation. For this purpose we established a subclone (JPX-9) of Jurkat cells that was stably transfected with an expression plasmid containing the p40tax gene, whose expression is definitely dependent on heavy-metal ions. Expression of the interleukin-2 receptor alpha chain in JPX-9 cells was induced in response to the induction of p40tax expression, as has been demonstrated by others in transient transfection experiments with Jurkat cells. In addition, we found that significant enhancement of expression of the nuclear proto-oncogene c-fos was closely associated with expression of p40tax. Continous enhancement in the level of c-fos mRNA was observed in the presence of p40tax. In contrast, mRNA levels of other nuclear proto-oncogenes (c-myc, c-myb, and c-jun) were not appreciably effected by the expression of p40tax. These results suggest that (i) in addition to the interleukin-2-interleukin-2 receptor system, cellular genes such as c-fos, which regulate normal T-cell growth, are also activated directly or indirectly by p40tax and (ii) p40tax-induced modulation of gene expression plays a crucial role in T-cell transformation by HTLV-I. PMID: 2501514 [PubMed - indexed for MEDLINE] ---------------------------------------------------------------