1: J Cell Biochem. 2005 Sep 19; [Epub ahead of print] Distinct localizations and repression activities of MM-1 isoforms toward c-Myc. Hagio Y, Kimura Y, Taira T, Fujioka Y, Iguchi-Ariga SM, Ariga H. Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan. MM-1 was identified as a c-Myc-binding protein and has been reported to repress the E-box-dependent transcription activity of c-Myc by recruiting HDAC1 complex via TIF1 beta/KAP1. In this study, originally isolated MM-1 was found to be a fusion protein comprised of the N-terminal 13 amino acids from the sequence of chromosome 14 and of the rest of the amino acids from that of chromosome 12 and was found to be expressed ubiquitously in all human tissues. Four splicing isoforms of MM-1, MM-1alpha, MM-1beta, MM-1gamma, and MM-1delta, which are derived from the sequence of chromosome 12, were then identified. Of these isoforms, MM-1alpha, MM-1gamma, and MM-1delta were found to be expressed in tissue-specific manners and MM-1beta was found to be expressed ubiquitously. Although all of the isoforms potentially possessed c-Myc- and TIF1beta-binding activities, MM-1beta and MM-1delta were found to be mainly localized in the cytoplasm and MM-1alpha and MM-1gamma were found to be localized in the nucleus together with both c-Myc and TIF1beta. Furthermore, when repression activities of MM-1 isoforms toward c-Myc transcription activity were examined by reporter gene assays in HeLa cells, MM-1alpha, MM-1gamma, and MM-1gamma, but not MM-1beta, were found to repress transcription activity of c-Myc, and the degrees of repression by MM-1gamma and MM-1delta were smaller than those by MM-1 and MM-1alpha. These results suggest that each MM-1 isoform distinctly regulates c-Myc transcription activity in respective tissues. J. Cell. Biochem. (c) 2005 Wiley-Liss, Inc. PMID: 16173081 [PubMed - as supplied by publisher] --------------------------------------------------------------- 2: Mol Phylogenet Evol. 2005 Jun;35(3):536-55. Epub 2005 Apr 7. Cenozoic biogeography and evolution in direct-developing frogs of Central America (Leptodactylidae: Eleutherodactylus) as inferred from a phylogenetic analysis of nuclear and mitochondrial genes. Crawford AJ, Smith EN. Naos Labs, Smithsonian Tropical Research Institute, Apartado 2072, Balboa, Ancon, Panama. andrew@dna.ac We report the first phylogenetic analysis of DNA sequence data for the Central American component of the genus Eleutherodactylus (Anura: Leptodactylidae: Eleutherodactylinae), one of the most ubiquitous, diverse, and abundant components of the Neotropical amphibian fauna. We obtained DNA sequence data from 55 specimens representing 45 species. Sampling was focused on Central America, but also included Bolivia, Brazil, Jamaica, and the USA. We sequenced 1460 contiguous base pairs (bp) of the mitochondrial genome containing ND2 and five neighboring tRNA genes, plus 1300 bp of the c-myc nuclear gene. The resulting phylogenetic inferences were broadly concordant between data sets and among analytical methods. The subgenus Craugastor is monophyletic and its initial radiation was potentially rapid and adaptive. Within Craugastor, the earliest splits separate three northern Central American species groups, milesi, augusti, and alfredi, from a clade comprising the rest of Craugastor. Within the latter clade, the rhodopis group as formerly recognized comprises three deeply divergent clades that do not form a monophyletic group; we therefore restrict the content of the rhodopis group to one of two northern clades, and use new names for the other northern (mexicanus group) and one southern clade (bransfordii group). The new rhodopis and bransfordii groups together form the sister taxon to a clade comprising the biporcatus, fitzingeri, mexicanus, and rugulosus groups. We used a Bayesian MCMC approach together with geological and biogeographic assumptions to estimate divergence times from the combined DNA sequence data. Our results corroborated three independent dispersal events for the origins of Central American Eleutherodactylus: (1) an ancestor of Craugastor entered northern Central America from South American in the early Paleocene, (2) an ancestor of the subgenus Syrrhophus entered northern Central America from the Caribbean at the end of the Eocene, and (3) a wave of independent dispersal events from South America coincided with formation of the Isthmus of Panama during the Pliocene. We elevate the subgenus Craugastor to the genus rank. PMID: 15878124 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 3: Proc Natl Acad Sci U S A. 2005 Mar 22;102(12):4506-11. Epub 2005 Mar 14. A target selection of somatic hypermutations is regulated similarly between T and B cells upon activation-induced cytidine deaminase expression. Kotani A, Okazaki IM, Muramatsu M, Kinoshita K, Begum NA, Nakajima T, Saito H, Honjo T. Department of Medical Chemistry and Molecular Biology, Graduate School of Medicine, Kyoto University, Yoshida Konoe-Cho, Sakyo-Ku, Kyoto 606-8501, Japan. Activation-induced cytidine deaminase (AID) is essential for somatic hypermutations (SHM) and class switch recombination. Overexpression of AID in non-B cells can induce SHM in artificial constructs inserted in various loci in the genome. AID overexpression was thus proposed to introduce mutations in a wide variety of genes with little specificity. We previously showed that AID transgenic mice developed T cell lymphomas in which the variable region beta genes of the T cell receptor and c-myc were mutated as frequently as SHM in activated B cells. To understand the target specificity of SHM in AID-expressing T lymphomas, we sequenced six oncogenes (c-myc, pim1, p53, atm, tgfbr-2, and k-ras) and two genes (cd4 and cd5) that are actively transcribed in T lymphomas. SHM was found only in c-myc, pim1, cd4, and cd5, which share the E47 binding motif in the enhancer/promoter. The rest that are not mutated in B cells were not mutated in AID-induced T lymphomas either, although they are transcribed in T and B cells. Comparison of several features of SHM, including selection of targets and mutation distribution, suggests that the regulatory mechanism of SHM is similar between T and B cells. SHM base specificities in the CD4 and CD5 genes were biased to AT, indicating that the preference of target bases of the mutations generated by overexpression of AID is not always GC bases but variable between target genes. PMID: 15767564 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 4: Pediatr Hematol Oncol. 2004 Sep;21(6):495-504. Long-term results of high-dose chemotherapy and autologous stem cell rescue for high-risk neuroblastoma patients: a report of the Spanish working party for BMT in children (Getmon). Verdeguer A, Munoz A, Canete A, Pardo N, Martinez A, Donat J, Gomez P, Bureo E, Fernandez JM, Cubells J, Maldonado M, Sastre A. Hospital Infantil La Fe, Valencia, Spain. The authors retrospectively analyzed the long-term outcome of 67 patients over 1 year of age at diagnosis with high-risk neuroblastoma (stage 4 or stage 3 with N-myc amplification) who were treated with megatherapy and stem cell rescue from 1984 to 1998. Median age at transplant was 4 years (range 1.6-15 years). The source of cells was peripheral stem cells in 29 and bone marrow in 38 patients. In 12 patients, an in vitro purging of bone marrow harvest was performed. Most patients were conditioned with melphalan, BCNU, and VM-26. After transplant 19 patients received complementary treatment with IL-2 (16) or 13-cis-retinoic acid (3). Six patients (8%) died from transplant-related toxicity and 39 from disease progression. Three patients were alive with active disease at the time of analysis. Nineteen patients are alive and disease-free at a median follow-up of 104 months. Five-year event-free survival is 0.30. Survival of patients who received a purged graft was not significantly better than the rest. Post-transplant complementary treatment significantly improved overall and event-free survival (p = .01 and p = .04, respectively). PMID: 15552813 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 5: Hepatobiliary Pancreat Dis Int. 2004 Aug;3(3):433-9. Distribution of oval cells and c-myc mRNA expression in mouse hepatocarcinogenesis. Fang CH, Zhang GQ, Zhu XY, Gong JQ. Department of Hepatobiliary Surgery, Zhujiang Hospital of the First Military Medical University, Guangzhou 510282, China. fch58520@sina.com BACKGROUND: This study was designed to assess the roles of oval cells and c-myc mRNA in the process of hepatocarcinogenesis and to clarify the function of carcinogene c-myc in the development of hepatocellular carcinoma (HCC) and the mechanism of inhibitory function of uscharidin on HCC in mouse hepatocarcinogenesis. METHODS: A total of 120 clean SD mice were divided into normal group, cancer induction group, and intervention group. The normal group was fed with standard forage while the rest two groups were given p-dimethylaminoazobenzene (DAB) to induce cancer. Thirteen weeks after induction of cancer, the two groups were fed with standard forage and water. Once the pattern was set up, the intervention group was given uscharidin injection into the abdominal cavity from the first week to the 14th week. On the 2nd, 4th, 6th, 8th, 10th, 12th, 14th, 16th, 18th, 20th, 22nd, and 24th week, all mice were killed and biopsied from the liver lobe for pathological analysis. At the same time, the number of tumor nodes was counted and the expression of c-myc mRNA was tested by RT-PCR. RESULTS: Since the 2nd week after cancer induction, proliferated oval cells could be seen in the portal area. Initially, the oval cells appeared in the cortical layer of the portal area, then proliferated gradually and immigrated into the liver parenchyma. In the period of fibrosis after liver proliferation, proliferated heaps of oval cells were noted in both portal and peripheral areas. In the period of carcinomatous change, oval cells could be seen both outside and inside of cancer nodes, but most of them were distributed outside. The c-myc gene was expressed negatively in the liver tissue of mice. The quantity of the expression began to increase at the time of infection of the liver and tended to increase with the degree of hepatic injury. In the period of canceration, the expression level of c-myc mRNA increased gradually. The intervention of uscharidin could not inhibit but delay the increase of the expression of c-myc mRNA. CONCLUSION: Oval cells are closely related to hepatocarcinoma cells, which play an important role in the occurrence and development of hepatocarcinogenesis. Uscharidin can inhibit the occurrence of hepatocarcinogenesis or local spreading at the early stage of cancer induction by DAB, but it cannot inhibit the expression of c-myc. PMID: 15313684 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 6: Ai Zheng. 2004 Mar;23(3):235-42. Circadian expression of dihydropyrimidine dehydrogenase, thymidylate synthase, c-myc and p53 mRNA in mouse liver tissue. Wu MW, Xian LJ, Li XM, Pasquale I, Francis L. INSERM E 0354 Chronotherape utique des cancers, Hopital Paul Brousse and Universite Paris XI, 94807 Villejuif Cedex, France. BACKGROUND & OBJECTIVE: Anti-cancer effect of 5-Fluorouracil (5-FU) is mediated mainly by inhibition of the thymidylate synthase (TS), while dihydropyrimidine dehydrogenase (DPD) is an initial and a rate-limiting catabolic enzyme of 5-FU. In this study, the mRNA expression profiles of TS, DPD, p53 and c-myc were investigated in mouse liver. METHODS: A total of 24 male B6D2F1 mice were involved in this study. All the mice were synchronized with an alternation of 12 h of light (L) and 12 h of darkness (D) (LD12:12) for 4 weeks. Body temperature and rest-activity were monitored with an intra-peritoneal sensor. All the mice were sacrificed at 3, 7, 11, 15, 19, 23 HALO (hours after light onset) respectively and liver samples were obtained and immediately frozen in liquid nitrogen. Total RNA was extracted from the frozen liver samples and one-step real-time quantitive RT-PCR was performed using LightCycler - RNA Amplification Kit SYBR Green I system. RESULTS: Both body temperature and rest-activity displayed similarly rhythmic patterns with peak times located in darkness, while the trough time was located in the light span. DPD showed a circadian expression in mRNA level with a peak at about 16 HALO (P=0.0012). TS showed a trend for a circadian rhythm, with a peak during light (P=0.079). Neither c-myc nor p53 displayed significant circadian rhythm. CONCLUSION: The 24-h patterns in DPD and TS expression were approximately 12 h out of phase, supporting a coordinated regulation of both transcriptional pathways relevant for 5-FU chronopharmacology. PMID: 15025949 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 7: Exp Mol Med. 2003 Oct 31;35(5):379-84. Dexamethasone-induced differentiation of pancreatic AR42J cell involves p21(waf1/cip1) and MAP kinase pathway. Eum WS, Li MZ, Sin GS, Choi SY, Park JB, Lee JY, Kwon HY. Department of Physiology, College of Medicine, Hallym University, Chunchon 200-702, Korea. Dexamethasone converts pluripotent pancreatic AR42J cells into exocrine cells expressing digestive enzymes. In order to address molecular mechanism of this differentiation, we have investigated the role of mitogen-activated protein (MAP) kinase pathway and gene expressions of p21(waf1/cip1) and nuclear oncogenes (c-fos and c-myc) during AR42J cell differentiation. Dexamethasone markedly increased the intracellular and secreted amylase contents as well as its mRNA level. However, cell growth and DNA content were significantly decreased. With these phenotypic changes, AR42J cells induced transient mRNA expression of p21(waf1/cip1) gene, which reached maximal level by 6 h and then declined gradually toward basal state. In contrast to p21(waf1/cip1), c-fos gene expression was transiently inhibited by 6 h and then recovered to basal level by 24 h. Increased c-myc expression detected after 3 h, peaked by 12 h, and remained elevated during the rest of observation. Dexamethasone inhibited epidermal growth factor-induced phosphorylation of extracellular signal regulated kinase. Inhibition of MAP kinase pathway by PD98059 resulted in further elevation of the dexamethasone-induced amylase mRNA and p21(waf1/cip1) gene expression. These results suggest that p21(waf1/cip1) and nuclear oncogenes are involved in dexamethasone-induced differentiation and inhibition of MAP kinase pathway accelerates the conversion of undifferentiated AR42J cells into amylase-secreting exocrine cells. PMID: 14646591 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 8: Mol Biol Cell. 2003 Oct;14(10):3967-76. Epub 2003 Jul 11. Cell surface orifices of caveolae and localization of caveolin to the necks of caveolae in adipocytes. Thorn H, Stenkula KG, Karlsson M, Ortegren U, Nystrom FH, Gustavsson J, Stralfors P. Department of Cell Biology, Faculty of Health Sciences, Linkoping University, Linkoping SE58185, Sweden. Caveolae are noncoated invaginations of the plasma membrane that form in the presence of the protein caveolin. Caveolae are found in most cells, but are especially abundant in adipocytes. By high-resolution electron microscopy of plasma membrane sheets the detailed structure of individual caveolae of primary rat adipocytes was examined. Caveolin-1 and -2 binding was restricted to the membrane proximal region, such as the ducts or necks attaching the caveolar bulb to the membrane. This was confirmed by transfection with myc-tagged caveolin-1 and -2. Essentially the same results were obtained with human fibroblasts. Hence caveolin does not form the caveolar bulb in these cells, but rather the neck and may thus act to retain the caveolar constituents, indicating how caveolin participates in the formation of caveolae. Caveolae, randomly distributed over the plasma membrane, were very heterogeneous, varying in size between 25 and 150 nm. There was about one million caveolae in an adipocyte, which increased the surface area of the plasma membrane by 50%. Half of the caveolae, those larger than 50 nm, had access to the outside of the cell via ducts and 20-nm orifices at the cell surface. The rest of the caveolae, those smaller than 50 nm, were not open to the cell exterior. Cholesterol depletion destroyed both caveolae and the cell surface orifices. PMID: 14517311 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 9: World J Gastroenterol. 2003 Mar;9(3):474-8. Hepatocyte transformation and tumor development induced by hepatitis C virus NS3 c-terminal deleted protein. He QQ, Cheng RX, Sun Y, Feng DY, Chen ZC, Zheng H. Department of Pathology, Xiangya School of Medicine, Central South University, Changsha 410078, Hunan Province, China. AIM: To study the effect of hepatitis C virus nonstructural protein 3 c-terminal deleted protein (HCV NS3-5') on hepatocyte transformation and tumor development. METHODS: QSG7701 cells were transfected with plasmid pRcHCNS3-5' (expressing HCV NS3 c-terminal deleted protein) by lipofectamine and selected in G418. The expression of HCV NS3 gene and protein was determined by PCR and immunohistochemistry respectively. Biological behavior of transfected cells was observed through cell proliferation assay, anchorage-independent growth and tumor development in nude mice. The expression of HCV NS3 and c-myc proteins in the induced tumor was evaluated by immunohistochemistry. RESULTS: HCV NS3 was strongly expressed in QSG7701 cells transfected with plasmid pRcHCNS3-5' and the positive signal was located in cytoplasm. Cell proliferation assay showed that the population doubling time in pRcHCNS3-5' transfected cells was much shorter than that in pRcCMV and non-transfected cells (24 h, 26 h, 28 h respectively). The cloning ratio of cells transfected with pRcHCNS3-5', pRcCMV and non-transfected cells was 33 %, 1.46 %, 1.11 %, respectively, the former one was higher than that in the rest two groups (P<0.01). Tumor development was seen in nude mice inoculated with pRcHCNS3-5' transfected cells after 15 days. HE staining showed its feature of hepatocarcinoma, and immunohistochemistry confirmed the expressions of HCV NS3 and c-myc proteins in tumor tissue. The positive control group inoculated with HepG2 also showed tumor development, while no tumor developed in the nude mice injected with pRcCMV and non-transfected cells after 40 days. CONCLUSION: 1.HCV NS3 c-terminal deleted protein has transforming and oncogenic potential. 2. Human liver cell line QSG7701 may be used as a good model to study HCV NS3 pathogenesis. PMID: 12632500 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 10: Brain Res Mol Brain Res. 2002 Nov 15;107(2):89-96. Effect of the ubiquitous transcription factors, SP1 and MAZ, on NMDA receptor subunit type 1 (NR1) expression during neuronal differentiation. Okamoto S, Sherman K, Bai G, Lipton SA. Center for Neuroscience and Aging, The Burnham Institute, La Jolla, CA 92037, USA. The silencer factor NRSF/REST has been reported to restrict expression to neurons of a variety of genes, including that encoding NMDA receptor subunit type 1 (NR1), by suppressing transcription in nonneuronal cells. However, we recently reported that in addition to the absence of NRSF/REST-binding activity, another neuron-specific mechanism is necessary for high level expression of the NR1 gene in neurons. In this study, we explored the mechanism of induction of NR1 promoter activity during neuronal differentiation of the P19 cell line. We identified a 27 base pair GC-rich region in the promoter as an important element responsible for induction of the NR1 gene after neuronal differentiation. We found that the ubiquitous transcription factors SP1 and MAZ bind to this GC-rich region. Surprisingly, the binding activities of SP1 and MAZ are not remarkably changed after neuronal differentiation. Mutations in the SP1 and MAZ sites impair binding of SP1 and MAZ proteins and also decrease NR1 promoter activity. These findings suggest that SP1 and MAZ mediate enhancement of NR1 promoter activity during neuronal differentiation despite the fact that their binding activity does not change. PMID: 12425938 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 11: BMC Dev Biol. 2002 Jul 2;2:8. A transcriptional response to Wnt protein in human embryonic carcinoma cells. Willert J, Epping M, Pollack JR, Brown PO, Nusse R. Department of Developmental Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305 USA. jennifer.willert@cox.net BACKGROUND: Wnt signaling is implicated in many developmental decisions, including stem cell control, as well as in cancer. There are relatively few target genes known of the Wnt pathway. RESULTS: We have identified target genes of Wnt signaling using microarray technology and human embryonic carcinoma cells stimulated with active Wnt protein. The ~50 genes upregulated early after Wnt addition include the previously known Wnt targets Cyclin D1, MYC, ID2 and betaTRCP. The newly identified targets, which include MSX1, MSX2, Nucleophosmin, Follistatin, TLE/Groucho, Ubc4/5E2, CBP/P300, Frizzled and REST/NRSF, have important implications for understanding the roles of Wnts in development and cancer. The protein synthesis inhibitor cycloheximide blocks induction by Wnt, consistent with a requirement for newly synthesized beta-catenin protein prior to target gene activation. The promoters of nearly all the target genes we identified have putative TCF binding sites, and we show that the TCF binding site is required for induction of Follistatin. Several of the target genes have a cooperative response to a combination of Wnt and BMP. CONCLUSIONS: Wnt signaling activates genes that promote stem cell fate and inhibit cellular differentiation and regulates a remarkable number of genes involved in its own signaling system. PMID: 12095419 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 12: Folia Histochem Cytobiol. 2001;39 Suppl 2:81-3. Effect of tyrphostins on programmed cell death in colon adenocarcinoma cell line LS-180. Dudzisz-Sledz M, Mizerski G, Marzec B, Korszen-Pilecka I, Rudzki S, Wojcierowski J, Mandziuk S. Department of Human Genetics, Medical University, Lublin, Poland. mdudzisz@yahoo.com Programmed cell death is an important process in the regulation of cellular proliferation, rest, differentiation and death. It is a genetically controlled process with characteristic biochemical and morphological features. Apoptosis directly regulates tumorigenesis and its induction could be a useful method of cancer therapy. Cancer cells could be influenced by some factors which induce apoptosis. We investigated the influence of tyrphostins, that specifically inhibits protein tyrosine kinases and stops the cell cycle in apoptosis of the colon adenocarcinoma cell line LS180. We used them at the concentration of 1-10 microM for 24 and 48 hours. We detected apoptosis using techniques that monitor either biochemical and morphological features of this process, such as staining with 7-amino-actinomycin D, staining with Grunwald-Giemsa, TUNEL reaction, in situ hybridization and with immunoperoxidase staining procedures. We examined the expression of genes and proteins connected with programmed cell death (p53, c-myc, p21, bcl-2). We estimated the results by cytophotometry and documented them by colour photography. We found that tyrphostin rapidly inhibits the cell cycle, particularly at the concentration of 5 microM. The expression of genes and proteins was strongly correlated with the increased apoptotic cell death conforming to the results of TUNEL and staining methods. PMID: 11820638 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 13: Int J Cancer. 2001 Sep 20;95(5):329-31. Linkage disequilibrium pattern in the L-myc gene in Italian and Japanese non-small-cell lung-cancer patients. Spinola M, Nomoto T, Manenti G, Falvella FS, Brega Massone PP, Conti B, Cataldo I, Valagussa P, Incarbone M, Miyamoto K, Ushijima T, Dragani TA. Istituto Nazionale Tumori, Via G. Venezian 1, 20133 Milan, Italy. Italian and Japanese non-small-cell lung-cancer patients were genotyped for an intragenic L-myc EcoRI restriction site polymorphism previously reported to be associated with lung-tumor prognosis in Asian populations but not in Caucasians. Screening of the L-myc sequence in Italian samples allowed identification of 2 additional 3'-UTR SNPs, located 2.3-3.0 kb from the EcoRI polymorphism, but no coding polymorphism was found. No significant association was found between any of the 3 SNPs and lung-tumor prognosis in Italian patients, consistent with the reported difference between Caucasian and Asian populations. Moreover, the newly discovered polymorphisms in the Italian group were not present in Japanese patients. Significant LD between EcoRI and the 2 other SNPs was detected in the Italian population, whereas no significant LD between the 2 3'-UTR markers was detected despite their close proximity (0.7 kb). Thus, the disparate conclusions about the role of L-myc polymorphism in tumor prognosis among different populations may rest in population-specific LD between the functional gene and the L-myc polymorphism. Copyright 2001 Wiley-Liss, Inc. PMID: 11494234 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 14: Mol Biol Cell. 2000 Dec;11(12):4259-75. Exocyst is involved in cystogenesis and tubulogenesis and acts by modulating synthesis and delivery of basolateral plasma membrane and secretory proteins. Lipschutz JH, Guo W, O'Brien LE, Nguyen YH, Novick P, Mostov KE. Department of Anatomy, University of California, San Francisco, San Francisco, California 94143-0452, USA. Epithelial cyst and tubule formation are critical processes that involve transient, highly choreographed changes in cell polarity. Factors controlling these changes in polarity are largely unknown. One candidate factor is the highly conserved eight-member protein complex called the exocyst. We show that during tubulogenesis in an in vitro model system the exocyst relocalized along growing tubules consistent with changes in cell polarity. In yeast, the exocyst subunit Sec10p is a crucial component linking polarized exocytic vesicles with the rest of the exocyst complex and, ultimately, the plasma membrane. When the exocyst subunit human Sec10 was exogenously expressed in epithelial Madin-Darby canine kidney cells, there was a selective increase in the synthesis and delivery of apical and basolateral secretory proteins and a basolateral plasma membrane protein, but not an apical plasma membrane protein. Overexpression of human Sec10 resulted in more efficient and rapid cyst formation and increased tubule formation upon stimulation with hepatocyte growth factor. We conclude that the exocyst plays a central role in the development of epithelial cysts and tubules. PMID: 11102522 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 15: Proteins. 2000 Dec 1;41(4):485-97. Fluctuations between stabilizing and destabilizing electrostatic contributions of ion pairs in conformers of the c-Myc-Max leucine zipper. Kumar S, Nussinov R. Laboratory of Experimental and Computational Biology, National Cancer Institute, Frederick Cancer Research and Development Center, Frederick, Maryland, USA. In solution proteins often exhibit backbone and side-chain flexibility. Yet electrostatic interactions in proteins are sensitive to motions. Hence, here we study the contribution of ion pairs toward protein stability in a range of conformers which sample the conformational space in solution. Specifically, we focus on the electrostatic contributions of ion pairs to the stability of each of the conformers in the NMR ensemble of the c-Myc-Max leucine zipper and to their average energy minimized structure. We compute the electrostatic contributions of inter- and intra-helical ion pairs and of an ion pair network. We find that the electrostatic contributions vary considerably among the 40 NMR conformers. Each ion pair, and the network, fluctuates between being stabilizing and being destabilizing. This fluctation reflects the variability in the location of the ion pairing residues and in the geometric orientation of these residues, both with respect to each other and with respect to other charged groups in the rest of the protein. Ion pair interactions in the c-Myc-Max leucine zipper in solution depend on the protein conformer which is analyzed. Hence, the overall stabilizing (or destabilizing) contribution of an ion pair is conformer population-dependent. This study indicates that free energy calculations performed using the continuum electrostatics methodology are sensitive to protein conformational details. PMID: 11056036 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 16: Arch Biochem Biophys. 2000 Feb 15;374(2):306-12. Ubiquitylation and destruction of endogenous c-mycS by the proteasome: are myc boxes dispensable? Chen L, Smith L, Accavitti-Loper MA, Omura S, Bingham Smith J. Department of Pharmacology & Toxicology, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA. c-MycS proteins are truncated forms of the transcription factor which have been shown to be produced by translation initiation at internal methionines (101, 121, and 134) and to be functional in the regulation of gene expression, cell proliferation, and apoptosis. Treatment of human leukemia HL60 cells with lactacystin, a specific inhibitor of the proteasome, increased the steady-state levels of endogenous c-MycS proteins. The half-life of endogenous [(35)S]MycS was similar to that of c-Myc ( approximately 23 min) in HL60 cells. c-Myc(Delta2-143), which lacks the transcription regulatory domain, had a half-life which was similar to that of endogenous c-Myc in 293 and HL60 cells. Treatment of the cells with lactacystin stabilized [(35)S]Myc(Delta2-143) and [(35)S]Myc and caused multi-ubiquitin conjugates of c-Myc, c-MycS, and Myc(Delta2-143) to accumulate. These findings indicate that the Myc homology boxes and the rest of the transcription regulatory domain (the first 144 amino acids) are dispensable for ubiquitylation and rapid destruction of c-MycS and c-Myc by the proteasome. Copyright 2000 Academic Press. PMID: 10666312 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 17: J Interferon Cytokine Res. 1999 Nov;19(11):1245-52. Subcellular localization of interferon-inducible Myc/stat-interacting protein Nmi is regulated by a novel IFP 35 homologous domain. Lee ND, Chen J, Shpall RL, Naumovski L. Department of Pediatrics, Stanford Medical Center, CA 94305, USA. Nmi was initially identified through a yeast two-hybrid interaction with N-Myc but it also interacts with c-Myc, Max, Fos, and several other transcription factors, including signal transducer and activator of transcription (Stat) proteins. Nmi is an interferon (IFN)-inducible protein with 25% amino acid identity to the IFN-inducible protein IFP 35. We have found that this homology consists of a novel domain of approximately 90-92 amino acids (aa) that is repeated in tandem in each protein. This region, termed Nmi/IFP 35 domain (NID), is important for subcellular localization of Nmi. Full-length Nmi protein or deletion constructs containing a single NID are localized to the cytoplasm, but amino-terminal Nmi fragments of up to 92 aa containing neither NID are nuclear. Fusion of the amino-terminal end of Nmi to pyruvate kinase, an exclusively cytoplasmic protein, results in a cytoplasmic fusion protein, suggesting that the amino-terminal end of Nmi does not contain a classic nuclear localization signal (NLS). Fusion of the amino-terminal end of Nmi to green fluorescent protein (GFP), which is normally found in both nuclear and cytoplasmic compartments, does not alter GFP distribution, whereas fusion of a single NID to GFP targets the fusion to the cytoplasm. Fusion of a nuclear localization signal (NLS) to full-length Nmi or NID repeats targets the hybrid to the nucleus, suggesting that a strong NLS is dominant to the cytoplasmic localization function of NID. NID may mediate cytoplasmic localization of the full-length Nmi protein through NID-NID protein interactions as demonstrated by yeast two-hybrid assay, immunoprecipitation, and the presence of Nmi in a high molecular weight protein complex. These results suggest that Nmi is composed of a modular structure with an amino-terminal domain that when separated from the rest of the protein is nuclear. The carboxy-terminal two thirds of the protein is composed of two NID that mediate cytoplasmic localization of the full-length protein. PMID: 10574616 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 18: Indian J Exp Biol. 1998 May;36(5):447-55. Oncogene expression as detected by immunocytochemical staining in hormonally induced ovarian cell lines. Luthra K, Chapekar TN. Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India. To understand the nature and extent of oncogene involvement in the development of neoplasia, an experimental model of goat ovarian granulosa cells stimulated by LH was chosen. In the course of these studies, several cell lines were developed which were essentially non-tumorigenic primary cell lines. One of them, however, was spontaneously transformed being immortalized and tumorigenic. These cell lines, transformed and non-transformed, should serve as contralateral cell lines to study differential oncogene expression in hormonally induced cell proliferation, and elucidate possible hormone-oncogene nexus which may be operative in the genesis of cancer. In the present report, we have studied expression of c-myc, c-ras, c-myb, c-fos and c-sis cellular oncogenes in the cell lines by immunocytochemistry using monoclonal antibodies. In the rest of our text we refer to these cellular oncogenes as oncogenes. The results reveal differential expression of the oncogenes. The striking difference between the non-transformed AIMS/GRXII cells and the transformed AIMS/GRXVIII cells was the absence of ras protein expression in the transformed AIMS/GRXVIII cells which intensely expressed the c-myc, c-myb, c-fos, and c-sis proteins. c-ras protein was expressed in the non-transformed AIMS/GRXVIII cell line and primary cultures. c-myc protein was expressed exclusively in the AIMS/GRXVIII transformed cells. The myc activity seen in the transformed cell line may be correlated to cell proliferation. These results show the variation of phenotype in cell lines derived from a single tissue source. PMID: 9717461 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 19: Am J Pathol. 1998 Jul;153(1):141-8. Genetic alterations in hormone-refractory recurrent prostate carcinomas. Nupponen NN, Kakkola L, Koivisto P, Visakorpi T. Laboratory of Cancer Genetics, Institute of Medical Technology, University of Tampere and Tampere University Hospital, Finland. To study the genetic basis of tumor progression, we have screened 37 hormone-refractory prostate carcinomas for genetic changes by comparative genomic hybridization (CGH). All recurrent tumors showed genetic aberrations, with a mean total number of changes per tumor of 11.4 (range, 3 to 23). The most common genetic aberrations were losses of 8p (72.5%), 13q (50%), 1p (50%), 22 (45%), 19 (45%), 10q (42.5%), and 16q (42.5%) and gains of 8q (72.5%), 7q (40%), Xq (32.5%), and 18q (32.5%). The CGH results were further validated with fluorescence in situ hybridization (FISH) using probes for pericentromeric regions of chromosomes 7, 8, and 18 as well as probes for caveolin (7q31), c-myc (8q24), and bcl-2 (18q21.3). In addition, the samples had previously been analyzed for androgen receptor gene copy number. CGH and FISH results were concordant in 78% of cases. Seventeen of twenty-two tumors showed an increased copy number of c-myc by FISH. However, only 5 of 17 (29%) of the cases showed high-level (more than threefold) amplification. Both CGH and FISH findings suggested that in most of the cases 8q gain involves the whole q-arm of the chromosome. Four of seventeen (24%) cases showed increased copy number of bcl-2 by FISH; however, no high-level amplifications were found. To evaluate the clonal relationship of the primary and recurrent tumors, six primary-recurrent tumor pairs from the same patients were studied by CGH. In three of six cases (50%), the recurrent tumor had more than one-half of the aberrations found in the corresponding primary tumor, indicating a close clonal relationship. In the rest of the cases, such a linear clonal relationship was less evident. Altogether, these results suggest that recurrent prostate carcinomas are genetically unstable. The resulting heterogeneity may well underlie the poor responsiveness of hormone-refractory tumors to treatment. PMID: 9665474 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 20: Int Rev Cytol. 1998;178:1-40. Karyotypic evolution of cells in culture: a new concept. Mamaeva SE. Laboratory of Cell Morphology, Russian Academy of Sciences, St. Petersburg, Russia. The Chapter summarizes peculiarities of karyotypic variability during establishment and long-term cultivation of permanent cell lines. A new concept on pathways of karyotypic evolution of cells in culture is put forward. A detailed description is presented of the author's original approach of cytogenetic analysis of cell lines provided for a principally new characteristic of the cell line: its generalized reconstructed karyotype (GRK). Its use as a criterion to evaluate authenticity, purity, and stability of cell lines is discussed. Based on analysis of the GRK, two stages of karyotype evolution of cell lines are revealed: establishment and stabilization, different in karyotypic variability of the cell population and in peculiarities of clone selection. Comparison of peculiarities of karyotypic variability of leukemic and tumor cells both in vitro and in vivo was made, and general regularities of their karyotypic evolution have been established, such as nonrandom changes in the number and structure of chromosomes and deletion of one of the sex chromosomes, as well as regularities characteristic only of cells in culture in most human and animal cell lines (at least 85%) of disomy on all autosomes. The rest of the cell lines, 15%, are characterized by either partial or total monosomies on certain autosomes during long-term cultivation. Three main compensatory mechanisms of maintaining viability of cell lines that have lost genetic material are discussed: polyploidization of the initial cell clone, amplification of oncogenes (predominantly of mys family), and extracopying of whole autosomes or of their fragments. Publication Types: Review PMID: 9348667 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 21: Leuk Lymphoma. 1997 Jul;26(3-4):271-9. The A-myb transcription factor in neoplastic and normal B cells. Golay J, Facchinetti V, Ying G, Introna M. Department of Immunology and Cellular Biology, Istituto Ricerche Farmacologiche Mario Negri, Milan, Italy. The myb family of transcription factors has been strongly implicated in the regulation of cell growth and differentiation in the haematopoietic system. The v-myb oncogene, carried by avian defective retroviruses, causes leukaemias in the chicken and transforms haematopoietic cells in vitro. Its normal cellular equivalent c-myb, has been shown to promote the proliferation and block the differentiation of haematopoietic cells in several experimental models and is required for fetal haematopoiesis. Two other members of the family have been cloned more recently, A-myb and B-myb, which show sequence homology with c-myb in several domains, of which the DNA binding domain as well as other regulatory domains. Both have been shown to be transcription factors. B-myb is also involved in the control of proliferation and differentiation, but, unlike c-myb, it is expressed in many cell types. The third member of the family, A-myb, shows the most restricted pattern of expression, suggesting a very specific role for this transcription factor. A-myb is expressed in a subpopulation of normal B lymphocytes activated in vivo and localised in the germinal center of peripheral lymphoid organs and is not detected at significant levels in all other mature or immature haematopoietic populations studied, including bone marrow cells, T lymphocytes, granulocytes, monocytes, either at rest or after in vitro activation. These studies indicate that A-myb plays a role during a narrow window of normal B cell differentiation. A-myb expression has also been studied in a wide range of neoplastic B cells, representing the whole spectrum of B cell differentiation. A-myb is strongly expressed in Burkitt's lymphomas (BL) and slg+ B-acute lymphoblastic leukaemias (B-ALL) and not in all other leukaemias/lymphomas tested, with the exception of a subset of CLL (about 25% of cases). It is intriguing that the A-myb genome has been localised relatively close to the c-myc gene on chromosome 8, suggesting that the c-myc translocation in BL and B-ALL may affect A-myb transcription. Studies are in progress to investigate the functional relationship between A-myb and c-myc, particularly in the context of BL cells and to determine whether A-myb is deregulated in these cells. Publication Types: Review Review, Tutorial PMID: 9322889 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 22: Leukemia. 1997 Apr;11 Suppl 3:482-3. Establishment and characterization of 7,12-dimethylbenz[a]anthracene (DMBA)-induced rat erythroleukemia cell lines. Koh T, Osaka M, Sugiyama T. Department of Pathology and Tumor Biology, Graduate School of Medicine, Kyoto University, Japan. To investigate molecular mechanisms and biological behaviors of 7,12-dimethylbenz[a]anthracene (DMBA)-induced rat erythroleukemia, we established 8 new culture cell lines from 7 primary erythroleukemias. We designated them KYD-10, 12, 17, 32, 38, 44A, 44B, and 49. Representative clones isolated from each cell line in early passage were analyzed cytogenetically and genetically. All cell lines except KYD-12 possessed the specific N-ras mutation at the 2nd base of codon 61. Four of them showed #2 trisomy (KYD-10, 32, 38, 44B), and the rest normal diploid karyotype (2n). KYD-32 cells showed Robertson type II #2 trisomy which had never been clonally isolated in vitro although it was reported in some DMBA leukemias in vivo. We further studied the genomic imbalance related to the N-ras allele using mutant-allele-specific amplification (MASA) method. Deletion of normal N-ras allele was found in 5 of 8 cell lines. KYD-32 and 38 retained the normal N-ras allele. The specific N-ras mutation and allelic loss of wild type N-ras were correlated with advanced cell proliferation in culture probably independent of #2 trisomy. PMID: 9209432 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 23: Invest Ophthalmol Vis Sci. 1996 Sep;37(10):2068-80. Differential regulation of cytokine and receptor transcript expression in human corneal and limbal fibroblasts by epidermal growth factor, transforming growth factor-alpha, platelet-derived growth factor B, and interleukin-1 beta. Li DQ, Tseng SC. Department of Ophthalmology, Bascom Palmer Eye Institute, University of Miami School of Medicine, Florida 33101, USA. PURPOSE: To explore further the significance of three patterns of cytokine dialogues that have been characterized between human corneal and limbal epithelial cells and fibroblasts. METHODS: Northern hybridization of the transcript expression of type I cytokine receptors (EGFR, IL-1R, and PDGFR-beta), type II cytokines (bFGF, LIF, and TGF-beta 1), and type III cytokines (HGF and KGF) by human corneal and limbal fibroblasts was conducted under the modulation of TGF-alpha, PDGF-BB, IL-1 beta, and EGF (type I cytokines). The mechanism of upregulation by IL-1 beta was studied further with respect to proto-oncogene expression and under the treatment of cycloheximide and actinomycin D. RESULTS: Results showed that EGF upregulated LIF and HGF but downregulated KGF and M-CSF. Unlike EGF, TGF-alpha upregulated additional EGFR, PDGFR-beta, bFGF, and TGF-beta 1, suggesting that although they share the same EGFR, TGF-alpha, which is produced by epithelium, is more effective in activating fibroblasts than EGF, which is present in tears. The upregulation of PDGF-BB was similar to that of TGF-alpha, except that it further stimulated IL-8, supporting their synergistic roles in promoting wound healing. Uniquely, IL-1 beta upregulated KGF expression by limbal fibroblasts more than corneal fibroblasts and IL-8 and M-CSF expression, but it downregulated PDGFR-beta. In IL-1 beta, the upregulation of cytokines and receptors was preceded by the upregulation of c-fos, c-jun, and c-myc, and it was inhibited by actinomycin D. Its upregulation of LIF was superinduced, but the upregulation of bFGF and KGF was inhibited, and that of the rest was not affected by cycloheximide. CONCLUSIONS: These findings suggest that epithelial cells under stress or injury (producing IL-1) might preferentially activate limbal epithelial stem cells indirectly by fibroblasts and simultaneously might promote inflammation during wound healing. PMID: 8814146 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 24: 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] --------------------------------------------------------------- 25: Immunol Rev. 1994 Dec;142:321-42. Promotion and inhibition of activation-induced apoptosis in T-cell hybridomas by oncogenes and related signals. Green DR, Mahboubi A, Nishioka W, Oja S, Echeverri F, Shi Y, Glynn J, Yang Y, Ashwell J, Bissonnette R. Division of Cellular Immunology, La Jolla Institute for Allergy and Immunology, CA 92037. The Two Signal: Death/Survival Model suggests that cellular proliferation and physiological cell death should be intimately associated such that, in the absence of external influences, a normal cell departing from rest will have an equal probability of undergoing either process. The c-Myc protooncogene product has been implicated in cell cycle progression and in the control of gene expression, and more recently c-Myc has also been seen to promote apoptotic cell death. As predicted from the model, c-Myc-induced apoptosis is inhibited by growth factors or other anti-apoptotic signals including those provided by some oncogenes. Here, we discuss experiments that test the Two Signal: Death/Survival Model in the phenomenon of activation-induced apoptosis in T-cell hybridomas. Ligation of the antigen receptor on these cells leads to activation, resulting in cytokine production and apoptosis. Inhibition of c-Myc expression by addition of antisense oligodeoxynucleotides or transforming growth factor beta inhibits this form of apoptosis. Because c-Myc is known to bind to several cellular proteins, including Max, we further examined the effects of expression of a dominant negative Max on activation-induced apoptosis. We found that this Max mutant, which interferes with the function of the Myc/Max heterodimer, inhibits the induction of apoptosis by antigen receptor ligation. Thus, both Myc and Max play roles in activation-induced apoptosis, presumably via control of gene expression. Further, as predicted, signals generated from growth factor receptors or the v-Abl oncogene interfere with activation-induced apoptosis. In contrast, the anti-apoptotic effects of Bcl-2 are not active in this form of apoptosis. Finally, a role for Fas/Fas-ligand interactions in activation-induced apoptosis is considered. Publication Types: Review PMID: 7698799 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 26: Crit Rev Oncog. 1994;5(4):359-71. Retrodifferentiation and cell death. Hass R. Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02115. The reversibility of a differentiation program termed dedifferentiation, redifferentiation, or retrodifferentiation opens a spectrum of new possibilities for cellular development. During differentiation and retrodifferentiation, the expression of gene products associated with a differentiated phenotype and cell cycle regulation demonstrate inverse patterns. This effect requires a coordinated network that simultaneously controls cell growth and differentiation. In particular, crosstalk between induction of differentiation and G0/G1 cell cycle exit can be initiated and sustained by activated serine/threonine kinases and tyrosine kinases. Phosphorylation signals are relayed to certain genes or transcription factors such as Fos/Jun, EGR-1, NF-kappa B, MyoD, or the Myc/Max gene family. However, the precise regulation of these transcription factors to confer signals to differentiation-associated and cell cycle-regulatory genes remains unclear. Cell cycle exit into a transient G0'-arrest cycle or a terminal G0 phase is determined by a network of phosphorylation signals involving the retinoblastoma protein and a variety of factors such as the E2F family, cyclins, and cyclin-dependent kinases. In this context, a variety of differentiation-induced cell lines, including monocytic, neuronal, or muscle cells, can progress through the G0'-arrest cycle, whereby a certain population retains the capacity to retrodifferentiate and reenter the cell cycle. In contrast, the rest of the differentiated population enters the irreversible G0 phase (terminal commitment) that finally results in programmed cell death. The expression of growth arrest-specific (gas and gadd) genes is associated with the G0'-arrest cycle, and other factors, including c-myc, p53, mdm2, and bcl2/bclx, contribute to the regulation of the cell death program. Although the precise signaling cascade determining retrodifferentiation or cell death remains unclear, a coordinated inter- and intracellular regulation could establish a certain biological balance between these exclusive pathways. Consequently, a retrodifferentiation process may provide a potential for cell type conversion or transdifferentiation, whereby retrodifferentiated cells can be induced to develop via a different pathway according to tissue-specific requirements. Publication Types: Review Review, Tutorial PMID: 7711113 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 27: Am J Pediatr Hematol Oncol. 1993 Nov;15(4):410-5. Hypercalcemia: a dose-limiting toxicity associated with 13-cis-retinoic acid. Villablanca JG, Khan AA, Avramis VI, Reynolds CP. Department of Pediatrics, Childrens Hospital Los Angeles, CA 90027-6016. PURPOSE: 13-cis-Retinoic acid (cis-RA) has efficacy in the treatment and prevention of certain malignancies. In vitro effects against neuroblastoma include induction of differentiation, inhibition of proliferation, and decreased N-myc expression. We hypothesized that cis-RA may be effective against minimal residual disease in neuroblastoma patients. A phase I trial to determine the maximal tolerated dosage and toxicity of cis-RA in pediatric patients with neuroblastoma after bone marrow transplantation was initiated. PATIENTS AND METHODS: Forty-nine pediatric patients (status post-bone marrow transplant for neuroblastoma) were treated for 14 days with oral cis-RA in escalating doses from 100 to 200 mg/m2/day followed by a 14-day rest period for up to 12 months. RESULTS: In three of 39 patients (7.7%) evaluable for calcium levels, hypercalcemia (12.6-18.7 mg/dl) was the dose-limiting toxicity. Grade 1-3 hypercalcemia occurred in nine of 39 patients (23%). The overall incidence of hypercalcemia was 31% (12 of 39). Only one patient was symptomatic due to the hypercalcemia, with arthralgias and myalgias. The hypercalcemia resolved with temporary discontinuation of the drug and a 25% dose reduction for subsequent courses. CONCLUSIONS: Hypercalcemia is a novel dose-limiting toxicity for cis-RA. Patients receiving high doses of cis-RA should have monitoring of serum calcium levels. Publication Types: Case Reports PMID: 8214363 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 28: Jpn J Cancer Res. 1992 Nov;83(11):1192-7. Lack of allelic preference in amplification and loss of the c-myc oncogene in methylcholanthrene-induced mouse sarcomas. Niwa O, Kominami R. Department of Pathology, Hiroshima University. Sarcomas were induced in F1 mice between C57BL/6N and C3H/He strains by subcutaneous injection of methylcholanthrene. The c-myc oncogene was found to be amplified in 16 cases among 43 sarcomas of C57BL/6N x C3H/He mice and 1 case among 5 sarcomas of the reciprocal cross. The origin of the amplified allele was determined by the polymerase chain reaction single strand conformation polymorphism analysis. Among the 17 sarcomas, only one had both of the alleles amplified. The rest of the tumors carried the amplified c-myc allele coming either from C57BL/6N (9 cases) or from C3H/He (8 cases). These results indicate that the c-myc allele is amplified randomly in methylcholanthrene-induced mouse sarcomas irrespective of its origin, such as paternal or maternal allele and C57BL/6N or C3H/He allele. In addition to these changes, the unamplified c-myc oncogene was found to be lost in 12 cases out of the 17 sarcomas with the amplification. PMID: 1483933 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 29: Zhonghua Zhong Liu Za Zhi. 1991 Jul;13(4):261-4. [Expression of protooncogenes c-myb and c-myc during the hexamethylene bisacetamide (HMBA)-induced commitment to terminal differentiation of murine erythroleukemia cells] [Article in Chinese] Chen ZX. Jiangsu Institute of Hematology, Suzhou. Modulation of a number of protooncogene expression occurs during differentiation of eukaryotes. Changes in expression of c-myb and c-myc during the HMBA-induced terminal differentiation of murine erythroleukemia cells were characterized by an early decrease (within 4 hrs), followed by the recovery of c-myc mRNA by 10 hrs, and the retention of suppression of c-myb expression for the rest of the induction period. Two MELC variants were used to further define the relationship between the differentiation and the protooncogene expression. R1 was a MELC variant completely resistant to HMBA, and R1 (VCR), a vincristine resistant R1, became inducible by HMBA again. The cell differentiation and the c-myb and c-myc expression were determined on R1 or R1 (VCR) cultured with HMBA respectively. The results demonstrated that the c-myc mRNA increased and remained relatively high as the cells grew to a saturated density regardless of the induction of differentiation. The R1 (VCR) cultured with HMBA displayed an early decrease in c-myb mRNA and a subsequent suppression of its expression, while the R1 cultured with HMBA showed a stable level of c-myb mRNA. These results suggest that the c-myb expression, rather than c-myc expression, is closely related to the HMBA-induced terminal differentiation. PMID: 1806345 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 30: Neuromuscul Disord. 1991;1(1):47-53. Altered sodium channel behaviour causes myotonia in dominantly inherited myotonia congenita. Iaizzo PA, Franke C, Hatt H, Spittelmeister W, Ricker K, Rudel R, Lehmann-Horn F. Neurologische Klinik, Universitat Munchen, F.R.G. The cause of increased excitability in autosomal dominant myotonia congenita (MyC) was studied in resealed greater than 3-cm long segments of muscle fibres from eight patients. Three hours after biopsy only about 50% of the fibre segments had regained a normal resting potential. This differs from our experiences with normal muscle or other disorders of myotonia (e.g. recessive generalized myotonia) where nearly all cut fibres reseal and repolarize during this time. When the depolarized MyC fibre segments were placed in a solution containing 1 microM tetrodotoxin (TTX) they repolarized to -80 to -90 mV. In fibre segments with normal resting potential, in the absence of TTX, spontaneous myotonic runs were recorded intracellularly, occasionally with double spikes. For only one of the eight patients, the Cl- conductance was reduced (50% of the total membrane conductance vs the usual 75%), for the rest of the patients the steady-state current-voltage relationship was normal. Sodium currents through single membrane channels were recorded with a patch clamp. For every patient re-openings of the Na+ channels were observed throughout 10-ms depolarizing pulses. These are very uncommon in normal muscle. At potentials positive to the resting potential, the duration of the re-openings increased, but the current amplitude was the same. It is concluded that in myotonia congenita re-openings of Na+ channels are the major cause of hyperexcitability and that Cl- conductance is normal. If it is reduced in rare cases, it may potentiate the myotonia. PMID: 1668369 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 31: Int J Cancer. 1989 Jan 15;43(1):164-70. Levels of myc protein, as analyzed by flow cytometry, correlate with cell growth potential in malignant B-cell lymphomas. Holte H, Stokke T, Smeland E, Watt R, Blomhoff HK, Kaalhus O, Ohlsson R. Department of Pathology, Norwegian Cancer Hospital, Oslo. We have analyzed c-myc protein expression during the cell cycle in malignant B-cell lymphomas by dual flow cytometric detection of a fluoresceinated polyclonal anti-myc antibody and propidium iodide which binds stochiometrically to DNA. The data obtained were correlated to other parameters of cell activation such as histopathological grading, expression of the activation antigen 4F2, light scatter (proportional to cellular volume), DNA synthesis and percentage of S-phase cells. The c-myc protein level was strongly correlated to parameters of DNA synthesis/content. In addition, the oncoprotein level was largely unvarying from the late G1 phase through the rest of the cell cycle in both malignant cells and normal purified B cells stimulated to proliferate in vitro. PMID: 2642893 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 32: Biull Eksp Biol Med. 1988 Mar;105(3):326-9. [Cellular oncogene expression in human tumors transplantable to athymic mice] [Article in Russian] Spitkovskii DD, Revazova ES. Expression of 3 cellular oncogenes among 7 ones under investigation is identified in the majority of 20 strains of human tumors, passaged in nude mice without significant specificity as far as the type of the tumor is concerned. The levels of the expression of these 3 oncogenes (c-myc, c-fos, c-ras) were higher than the ones in primary human tumors except for the human melanoma Mel-2 strain, where the expression of c-myb oncogene was identified. All the rest oncogenes (c-mos, B-lym, c-sis, c-myb) showed no expression in human tumors of the examined strains. PMID: 3349173 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 33: EMBO J. 1986 Nov;5(11):2859-65. Intragenic pausing and anti-sense transcription within the murine c-myc locus. Nepveu A, Marcu KB. We present a detailed analysis of strand-specific transcription in different regions of the murine c-myc locus. In normal and transformed cell lines, RNA polymerase II directed transcription occurs in the sense and anti-sense direction. Three noncontiguous regions show a high level of transcription in the anti-sense orientation: upstream of the first exon, within the first intron and in the 3' part of the gene (intron 2 and exon 3). In a cell line carrying a c-myc amplification (54c12), anti-sense transcription is not uniformly increased throughout the locus and is differentially affected by inhibition of protein synthesis. These results suggest that anti-sense transcription in various parts of the locus is independently regulated. In the sense orientation, transcriptional activity is higher in the first exon than in the rest of the gene indicating that transcription pauses near the 3' end of the first exon. The extent of this intragenic pausing varies among different cell lines and is most severe in cells with a c-myc amplification. Transcription initiation and pausing are both negatively regulated by labile proteins. PMID: 3024965 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 34: Mol Cell Biol. 1985 Nov;5(11):2903-12. Growth-dependent synthesis of c-myc-encoded proteins: early stimulation by serum factors in synchronized mouse 3T3 cells. Persson H, Gray HE, Godeau F. Synthesis of the c-myc gene product was measured during the entire cell cycle of subconfluent mouse 3T3 cells with an antibody raised against a human c-myc synthetic peptide. The antiserum recognized two mouse c-myc-encoded proteins with apparent molecular weights in sodium dodecyl sulfate-polyacrylamide gels of 62,000 and 60,000. Cell-derived p62 was compared with the mouse c-myc gene product synthesized in vitro. Immunoprecipitation, electrophoretic analyses, and peptide mapping provided evidence that p62 is encoded by the mouse c-myc gene. The rate of synthesis of the c-myc proteins was tightly coupled to the cellular growth state of nontransformed A31 3T3 cells, but not to that of their benzo(a)pyrene-transformed derivative (BPA31). Furthermore, the synthesis of the c-myc proteins was stimulated by the exposure of confluent, density-arrested A31 cells to platelet-derived growth factor or fibroblast growth factor. Tightly synchronized cell populations were obtained on the addition of serum factors to subconfluent, serum-deprived A31 cells, and c-myc expression could be monitored for more than one complete cell cycle. One hour after stimulation the steady-state level of the 2.2 kilobase c-myc transcript increased 30-fold relative to that of quiescent cells and decreased thereafter to the level observed during exponential growth. The rate of synthesis of c-myc-encoded proteins was determined by immunoprecipitation after a 2-h labeling period. After an initial sevenfold increase detectable 2 h after serum addition, the rate of synthesis remained constant throughout the rest of the cell cycle. No further changes associated with the late prereplicative period, S phase, G2, or mitosis could be demonstrated. Pulse-chase and long-term labeling experiments revealed different half-lives for the two c-myc-encoded proteins. The half-lives of the c-myc proteins, however, were independent of the cellular growth state. The sustained expression observed throughout the cell cycle suggests that the growth-related function of c-myc may be required during the G0-G1 transition and in all phases of the cycle of the growing cell. PMID: 3915769 [PubMed - indexed for MEDLINE] ---------------------------------------------------------------