1: Cancer Cell. 2005 Aug;8(2):119-30. Early inactivation of p53 tumor suppressor gene cooperating with NF1 loss induces malignant astrocytoma. Zhu Y, Guignard F, Zhao D, Liu L, Burns DK, Mason RP, Messing A, Parada LF. Center for Developmental Biology and Kent Waldrep Foundation Center for Basic Research on Nerve Growth and Regeneration, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA. Malignant astrocytoma, the most prevalent primary brain tumor, is resistant to all known therapies and frequently harbors mutations that inactivate p53 and activate Ras signaling. We have generated mouse strains that lack p53 and harbor a conditional allele of the NF1 tumor suppressor that negatively regulates Ras signaling. The mice develop malignant astrocytomas with complete penetrance. The majority of tumors display characteristics of glioblastoma multiforme with concomitant alteration of signaling pathways previously described in the human counterparts of this neoplasm. We find that the sequence of tumor suppressor inactivation influences tumorigenicity and that earliest evidence of tumor formation localizes to regions of the brain that contain a multipotent stem cell population capable of in vivo differentiation into neurons and glia. PMID: 16098465 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 2: Eur J Cancer. 2005 Mar;41(5):807-15. Human papillomavirus-16 associated squamous cell carcinoma of the head and neck (SCCHN): a natural disease model provides insights into viral carcinogenesis. Ferris RL, Martinez I, Sirianni N, Wang J, Lopez-Albaitero A, Gollin SM, Johnson JT, Khan S. UPCI Research Pavilion, The Hillman Cancer Center, 5117 Centre Avenue, Room 1.19d, Pittsburgh, PA 15213-1863, USA. ferrisrl@upmc.edu Uncertainty regarding the causality of human papillomaviruses (HPVs) in squamous cell carcinoma of the head and neck (SCCHN) necessitates better in vitro models. We carried out molecular analyses of a novel, naturally HPV-16-transformed SCCHN cell line (UPCI:SCC090) and show high copy number of HPV-16 DNA, present in a head to tail, tandemly repeated integrated state. Sequence analysis of the HPV-16 long control region (LCR) in UPCI:SCC090 revealed a deletion of 163 bp, removing a portion of the enhancer sequence, including the binding sites for the transcription factors YY1 and NF1. The E6 and E7 oncogenes of HPV-16 are expressed at high levels in this cell lines, as determined by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR). UPCI:SCC090 contains wild-type tumour suppressor TP53 gene, and undetectable p53 protein, except after treatment with cisplatin, specific proteasome inhibitors or by E6 RNA interference, suggesting E6-dependent degradation of p53 in this cell line. The results of our studies are consistent with a causative role of HPV-16 in the pathogenesis of SCCHN. PMID: 15763658 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 3: J Neuropathol Exp Neurol. 2005 Jan;64(1):74-81. Expression patterns of cell cycle components in sporadic and neurofibromatosis type 1-related malignant peripheral nerve sheath tumors. Agesen TH, Florenes VA, Molenaar WM, Lind GE, Berner JM, Plaat BE, Komdeur R, Myklebost O, van den Berg E, Lothe RA. Department of Genetics, Institute for Cancer Research, Norwegian Radium Hospital, Montebello, 0310 Oslo, Norway. The molecular biology underlying the development of highly malignant peripheral nerve sheath tumors (MPNSTs) remains mostly unknown. In the present study, the expression pattern of 10 selected cell cycle components is investigated in a series of 15 MPNSTs from patients with (n = 9) or without (n = 5) neurofibromatosis type 1 (NF1). Thirteen tumors did not express the cyclin-dependent kinase inhibitor, p16(INK4A), an observation that was related to homozygote gene deletions in three tumors, heterozygote deletions in five, and gross gene rearrangements in five. The absence of protein expression in the tumors with one seemingly intact allele was not caused by promoter hypermethylation of p16(INK4A) or p14(ARF). All tumor samples expressed normal sized RB1, cyclin D3, CDK2, CDK4, p21(CIP1), and p27(KlP1) proteins, and only a single tumor showed an aberrant protein band for one of these proteins, p21(CIP1). Cyclin D1 was absent in four tumors; all except one tumor showed expression of TP53 protein, and three of nine MPNSTs had expression of normal-sized MDM2. In conclusion, this study shows that the vast majority of MPNSTs had gross rearrangements of the p16(INK4A) gene, explaining the absence of the encoded protein in the same tumors. The level of expression was equally distributed between the familial (NF1) and sporadic cases, although it should be noted that the 2 cases with p16(INK4A) expression were sporadic. The data imply that the complete absence of p16(INK4A) is sufficient for activation of the cell cycle in most MPNSTs; thus, it is not necessary for tumor proliferation to further stimulate the cycle through alteration of other central components. PMID: 15715087 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 4: Cancer Cell. 2005 Jan;7(1):65-75. Role for the epidermal growth factor receptor in neurofibromatosis-related peripheral nerve tumorigenesis. Ling BC, Wu J, Miller SJ, Monk KR, Shamekh R, Rizvi TA, Decourten-Myers G, Vogel KS, DeClue JE, Ratner N. Departments of Cell Biology, Neurobiology, and Anatomy, University of Cincinnati College of Medicine, Cincinnati, Ohio 45267, USA. Benign neurofibromas and malignant peripheral nerve sheath tumors are serious complications of neurofibromatosis type 1. The epidermal growth factor receptor is not expressed by normal Schwann cells, yet is overexpressed in subpopulations of Nf1 mutant Schwann cells. We evaluated the role of EGFR in Schwann cell tumorigenesis. Expression of EGFR in transgenic mouse Schwann cells elicited features of neurofibromas: Schwann cell hyperplasia, excess collagen, mast cell accumulation, and progressive dissociation of non-myelin-forming Schwann cells from axons. Mating EGFR transgenic mice to Nf1 hemizygotes did not enhance this phenotype. Genetic reduction of EGFR in Nf1(+/-);p53(+/-) mice that develop sarcomas significantly improved survival. Thus, gain- and loss-of-function experiments support the relevance of EGFR to peripheral nerve tumor formation. PMID: 15652750 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 5: Toxicol Pathol. 2004 Mar-Apr;32 Suppl 1:90-8. Mouse models of human familial cancer syndromes. Ward JM, Devor-Henneman DE. Veterinary and Tumor Pathology Section, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702-1201, USA. jw11by@nih.gov As many as 5% of human cancers appear to be of hereditable etiology. Of the more than 50 characterized familial cancer syndromes, most involve disease affecting multiple organs and many can be traced to one or more abnormalities in specific genes. Studying these syndromes in humans is a difficult task, especially when it comes to genes that may manifest themselves early in gestation. It has been made somewhat easier with the development of genetically engineered mice (GEM) that phenotypically mimic many of these inheritable human cancers. The past 15 years has seen the establishment of mouse lines heterozygous or homozygous null for genes known or suspected of being involved in human cancer syndromes, including APC, ATM, BLM, BRCA1, BRCA2, LKB1, MEN1, MLH, MSH, NF1, TP53, PTEN, RB1, TSC1, TSC2, VHL, and XPA. These lines not only provide models for clinical disease and pathology, but also provide avenues to investigate molecular pathology, gene-gene and protein-tissue interaction, and, ultimately, therapeutic intervention. Possibly of even greater importance, they provide a means of looking at placental and fetal tissues, where genetic abnormalities are often first detected and where they may be most easily corrected. We will review these mouse models, examine their usefulness in medical research, and furnish sources of animals and references. Publication Types: Review Review, Tutorial PMID: 15209408 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 6: Toxicol Pathol. 2004;32(Supplement 1):90-98. Mouse Models of Human Familial Cancer Syndromes. Ward JM, Devor-Henneman DE. Veterinary and Tumor Pathology Section, Center for Cancer Research, National Cancer Institute, Frederick, Maryland 21702-1201, USA. As many as 5% of human cancers appear to be of hereditable etiology. Of the more than 50 characterized familial cancer syndromes, most involve disease affecting multiple organs and many can be traced to one or more abnormalities in specific genes. Studying these syndromes in humans is a difficult task, especially when it comes to genes that may manifest themselves early in gestation. It has been made somewhat easier with the development of genetically engineered mice (GEM) that phenotypically mimic many of these inheritable human cancers. The past 15 years has seen the establishment of mouse lines heterozygous or homozygous null for genes known or suspected of being involved in human cancer syndromes, including APC, ATM, BLM, BRCA1, BRCA2, LKB1, MEN1, MLH, MSH, NF1, TP53, PTEN, RB1, TSC1, TSC2, VHL, and XPA. These lines not only provide models for clinical disease and pathology, but also provide avenues to investigate molecular pathology, gene-gene and protein-tissue interaction, and, ultimately, therapeutic intervention. Possibly of even greater importance, they provide a means of looking at placental and fetal tissues, where genetic abnormalities are often first detected and where they may be most easily corrected. We will review these mouse models, examine their usefulness in medical research, and furnish sources of animals and references. PMID: 15204993 [PubMed - as supplied by publisher] --------------------------------------------------------------- 7: Oncogene. 2004 Feb 5;23(5):1146-52. Notch and Schwann cell transformation. Li Y, Rao PK, Wen R, Song Y, Muir D, Wallace P, van Horne SJ, Tennekoon GI, Kadesch T. Department of Neurology and Pediatrics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA. Benign plexiform neurofibromas in NF1 patients can transform spontaneously into malignant peripheral nerve sheath tumors (MPNSTs). Although mutations in the p53 gene have been found in a subset of MPNSTs and mouse models support a role for p53 mutations in malignant conversion, we found that each of three Schwann cell lines derived from human MPNSTs possessed active p53. One of the lines expressed the Notch intracellular domain (NICD), indicative of ongoing Notch signaling. Consistent with a role in malignancy, NICD was able to transform primary rat Schwann cells. Transformation was robust--NICD-transduced cells generated tumors in nude rats--and was associated with the loss of markers associated with Schwann cell differentiation. These data suggest that aberrant Notch signaling may contribute to the conversion of benign neurofibromas to MPNSTs. PMID: 14762442 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 8: Hum Mutat. 2004 Feb;23(2):134-46. Characterization of the somatic mutational spectrum of the neurofibromatosis type 1 (NF1) gene in neurofibromatosis patients with benign and malignant tumors. Upadhyaya M, Han S, Consoli C, Majounie E, Horan M, Thomas NS, Potts C, Griffiths S, Ruggieri M, von Deimling A, Cooper DN. Institute of Medical Genetics, University of Wales College of Medicine, Cardiff, UK. upadhyaya@cardiff.ac.uk One of the main features of neurofibromatosis type 1 (NF1) is benign neurofibromas, 10-20% of which become transformed into malignant peripheral nerve sheath tumors (MPNSTs). The molecular basis of NF1 tumorigenesis is, however, still unclear. Ninety-one tumors from 31 NF1 patients were screened for gross changes in the NF1 gene using microsatellite/restriction fragment length polymorphism (RFLP) markers; loss of heterozygosity (LOH) was found in 17 out of 91 (19%) tumors (including two out of seven MPNSTs). Denaturing high performance liquid chromatography (DHPLC) was then used to screen 43 LOH-negative and 10 LOH-positive tumors for NF1 microlesions at both RNA and DNA levels. Thirteen germline and 12 somatic mutations were identified, of which three germline (IVS7-2A>G, 3731delT, 6117delG) and eight somatic (1888delG, 4374-4375delCC, R2129S, 2088delG, 2341del18, IVS27b-5C>T, 4083insT, Q519P) were novel. A mosaic mutation (R2429X) was also identified in a neurofibroma by DHPLC analysis and cloning/sequencing. The observed somatic and germline mutational spectra were similar in terms of mutation type, relative frequency of occurrence, and putative underlying mechanisms of mutagenesis. Tumors lacking mutations were screened for NF1 gene promoter hypermethylation but none were found. Microsatellite instability (MSI) analysis revealed MSI in five out of 11 MPNSTs as compared to none out of 70 neurofibromas (p=1.8 x 10(-5)). The screening of seven MPNSTs for subtle mutations in the CDKN2A and TP53 genes proved negative, although the screening of 11 MPNSTs detected LOH involving either the TP53 or the CDKN2A gene in a total of four tumors. These findings are consistent with the view that NF1 tumorigenesis is a complex multistep process involving a variety of different types of genetic defect at multiple loci. Copyright 2003 Wiley-Liss, Inc. PMID: 14722917 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 9: Neurology. 2003 Nov 25;61(10):1397-400. Molecular analysis of astrocytomas presenting after age 10 in individuals with NF1. Gutmann DH, James CD, Poyhonen M, Louis DN, Ferner R, Guha A, Hariharan S, Viskochil D, Perry A. Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA. gutmannd@neuro.wustl.edu BACKGROUND: Fifteen to 20% of children with neurofibromatosis type 1 (NF1) develop low-grade astrocytomas. Although brain tumors are less common in teenagers and adults with NF1, recent studies have suggested that patients with NF1 are at a significantly increased risk of developing astrocytomas. OBJECTIVE:S: To investigate the genetic basis for astrocytoma development in patients with NF1 beyond the first decade of life. METHODS: The authors performed molecular genetic analyses of 10 NF1-associated astrocytomas representing all World Health Organization (WHO) malignancy grades using fluorescence in situ hybridization, loss of heterozygosity, immunohistochemistry, and direct sequencing. RESULTS: Later-onset NF1-associated astrocytomas, unlike histologically identical sporadic astrocytomas, exhibit NF1 inactivation, supporting a direct association with NF1 rather than a chance occurrence. Furthermore, some of these astrocytomas have homozygous NF1 deletion. In addition, genetic changes observed in high-grade sporadic astrocytomas, including TP53 mutation and CDKN2A/p16 deletion, are also seen in NF1-associated high-grade astrocytomas. CONCLUSIONS: Neurofibromatosis type 1-associated astrocytomas occurring in patients older than 10 years exhibit genetic changes observed in sporadic high-grade astrocytomas. Patients with neurofibromatosis type 1 and germline NF1 deletions may be at risk for developing late-onset astrocytomas. PMID: 14638962 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 10: Pathol Oncol Res. 2003;9(3):201-5. Epub 2003 Oct 7. Malignant peripheral nerve sheath tumors associated with neurofibromatosis type 1. Bilgic B, Ates LE, Demiryont M, Ozger H, Dizdar Y. Department of Pathology, Istanbul University, Istanbul Medicine Faculty, Capa, Istanbul, Turkey. We report 4 cases of malignant peripheral nerve sheath tumors (MPNST) with neurofibromatosis type 1 (NF1). Mean age was 29.5. Two of them had a family history. Three of them were male. All of them had enlarging mass and pain in the background of neurofibromas. Locations were popliteal, thigh and forearm. The masses were greater than 5 cm in diameter in each case. In two cases the mass was showing continuity with a nerve. One patient had a nonossifying fibroma as well as a MPNST. Wide excision and radiotherapy were applied to three of the patients. One of them did not take any therapy after surgical resection. Two of the patients died of lung metastases after a mean period of 12.5 months. In a majority of NF1 patients MPNST emerges from a preexisting neurofibroma. The patients with NF1 are at greatest risk for developing sarcomas, so they should be followed closely. Publication Types: Case Reports PMID: 14530818 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 11: Oncogene. 2003 Sep 4;22(38):6061-70. The p53 tumor suppressor gene is regulated in vivo by nuclear factor 1-C2 in the mouse mammary gland during pregnancy. Johansson EM, Kannius-Janson M, Bjursell G, Nilsson J. Department of CMB/Molecular Biology, Box 462, S-405 30 Goteborg, Sweden. Eva.Johansson@molbio.gu.se The p53 tumor suppressor protein plays an important role in preventing cancer development by arresting or killing potential tumor cells. Downregulated p53 levels, or mutations within the p53 gene, leading to the loss of p53 activity, are found in many breast carcinomas. Here we demonstrate that the p53 gene is transcriptionally upregulated in the normal mouse mammary gland at midpregnancy. We show that the specific isoform nuclear factor 1-C2 (NF1-C2) plays an important role in this activation. Functional mutation of the NF1-binding site in the mouse p53 promoter resulted in a reduction of the gene expression to less than 30% in mammary epithelial cells. By the use of two powerful techniques, chromatin immunoprecipitation and oligonucleotide decoy, we verify the importance of NF1-C2 in p53 gene activation in vivo. These findings demonstrate a broader role for NF1-C2 in the mammary gland at midpregnancy, beyond its earlier reported activation of milk protein genes. We also demonstrate that NF1-A1 proteins are produced in the mouse mammary gland. However, due to their lower affinity to the NF1-binding site, these proteins are not involved in the transcriptional upregulation of p53 at midpregnancy. This paper constitutes the first report demonstrating the importance of NF1 proteins in the p53 gene activation in the mouse mammary gland. It is also the first time that p53 gene activation is coupled to a specific, endogenously expressed NF1 isoform. PMID: 12955085 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 12: Cancer Res. 2002 Aug 1;62(15):4507-13. Epidermal growth factor receptor signaling pathways are associated with tumorigenesis in the Nf1:p53 mouse tumor model. Li H, Velasco-Miguel S, Vass WC, Parada LF, DeClue JE. Laboratory of Cellular Oncology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA. The human disease neurofibromatosis type 1 (NF1) is caused by mutations in the NF1 gene, and is characterized by the formation of benign and malignant tumors of the peripheral nervous system. We have shown previously that aberrant expression of the epidermal growth factor receptor (EGFR) is a common feature of human NF1-related tumor development in humans and in NF1 animal models. One recent approach taken to investigate the changes associated with NF1 tumor formation is the development of the Nf1:p53 mouse tumor model. Here, we examined a series of tumor cell lines derived from Nf1:p53 mice for their expression of EGFR family members. Immunoblotting analyses revealed that 23 of the 24 cell lines examined express the EGFR, and 24 of 24 express the related tyrosine kinase erbB2, whereas erbB3 was detected in only 6 of 24. All of the cell lines expressing EGFR responded to epidermal growth factor (EGF) by activation of the downstream signaling pathways, mitogen-activated protein (MAP)/extracellular signal-regulated kinase kinase/MAP kinase, and phosphatidylinositol 3'-kinase (PI3k)/AKT. Growth of the cell lines was greatly stimulated by EGF in vitro and could be blocked by an antagonist of the EGFR. In addition, inhibition of the PI3k pathway potently inhibited the EGF-dependent growth of these cell lines, whereas inhibition of the MAP/extracellular signal-regulated kinase kinase/MAP kinase pathway had more limited effects. We conclude that EGFR expression is a common feature of the Nf1:p53 tumor cell lines and that inhibition of this molecule or its downstream target PI3k, may be useful in the treatment of NF1-related malignancies. PMID: 12154062 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 13: Am J Clin Pathol. 2002 Jul;118(1):93-100. Kinetic profiles by topographic compartments in muscle-invasive transitional cell carcinomas of the bladder: role of TP53 and NF1 genes. Blanes A, Rubio J, Martinez A, Wolfe HJ, Diaz-Cano SJ. Department of Pathology, University Hospital, Malaga, Spain. We evaluated 71 muscle-invasive transitional cell carcinomas (TCCs) of the bladder by tumor compartments. Kinetic parameters included mitotic figure counting, Ki-67 index, proliferation rate (DNA slide cytometry), and apoptotic index (in situ end labeling [ISEL] of fragmented DNA using digoxigenin-labeled deoxyuridine triphosphate and Escherichia coli DNA polymerase [Klenow fragment]). At least 50 high-power fields per compartment were screened from the same tumor areas; results are expressed as percentage of positive neoplastic cells. Mean and SD were compared by tumor compartment. DNA was extracted from microdissected samples (superficial and deep) and used for microsatellite analysis of TP53 and NF1 by polymerase chain reaction-denaturing gradient gel electrophoresis. Significantly higher marker scores were revealed in the superficial compartment than in the deep compartment. An ISEL index of less than 1% was revealed in 63% (45/71) of superficial compartments and 86% (61/71) of deep compartments. Isolated NF1 alterations were observed mainly in superficial compartments, whereas isolated TP53 abnormalities were present in deep compartments. Lower proliferation and down-regulation of apoptosis define kinetically the deep compartment of muscle-invasive TCC of the bladder and correlate with the topographic heterogeneity, NF1-defective in superficial compartments and TP53-defective in deep compartments. PMID: 12109862 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 14: J Pathol. 2002 May;197(1):98-107. Frequent genomic imbalances in chromosomes 17, 19, and 22q in peripheral nerve sheath tumours detected by comparative genomic hybridization analysis. Koga T, Iwasaki H, Ishiguro M, Matsuzaki A, Kikuchi M. First Department of Pathology, School of Medicine, Fukuoka University, Japan. Comparative genomic hybridization (CGH) was used to detect changes in relative chromosome copy number in 50 cases of peripheral nerve sheath tumour (PNSTs), including nine malignant peripheral nerve sheath tumours (MPNSTs), 27 neurofibromas (with three plexiform neurofibromas) and 14 schwannomas. Chromosome imbalances were frequently detected in benign as well as malignant PNSTs. In both NF1-associated and sporadic MPNSTs, the number of gains was higher than the number of losses, suggesting proto-oncogene activation during MPNST progression. NF1-asociated MPNSTs exhibited gains of chromosomes 17q and X (2/4 cases each), whereas sporadic MPNSTs showed gains of chromosome 4q (3/5 cases). On the other hand, in benign neurofibromas and schwannomas, the number of losses was higher than the number of gains, suggesting a predominant role of tumour suppressor genes in tumourigenesis. Both sporadic and NF1-associated neurofibromas exhibited losses at chromosome 22q in more than 50% of cases. These chromosomal regions may contain common chromosomal abnormalities characteristic of both types of neurofibromas. In NF1-associated neurofibromas, most frequent losses were found in chromosomes 17 [17p11.2-p13 in nine cases (60%); 17q24-25 in 6 cases (40%)] and 19 [19p13.2 in eight cases (53%); 19q13.2-qter in eight cases (53%)], whereas in sporadic neurofibromas and schwannomas losses of chromosomes 17 and 19 were detected in less than 50% of cases. Since this 17p11.2-p13 region is known to contain the tumour suppressor gene TP53, patients with NF1 may be at high risk of malignant neoplasms including MPNSTs. Gains were more frequently detected in plexiform neurofibromas (2/3 cases) than other benign tumours, suggesting proto-oncogene activation in tumourigenesis of plexiform neurofibroma. The significance of the losses of chromosome 19 in these cases is not clear at present, but in NF1-associated neurofibromas, the presence of some as yet unknown tumour suppressor genes on chromosome 19 cannot be ruled out. PMID: 12081210 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 15: Virchows Arch. 2002 Jun;440(6):610-5. Epub 2001 Nov 16. Immunohistochemical and molecular analysis of p53, RB, and PTEN in malignant peripheral nerve sheath tumors. Mawrin C, Kirches E, Boltze C, Dietzmann K, Roessner A, Schneider-Stock R. Department of Neuropathology, Otto-von-Guericke-University, Magdeburg, Germany. The molecular basis of both sporadic and neurofibromatosis type 1 (NF1)-associated malignant peripheral nerve sheath tumors (MPNSTs) is yet largely undetermined. Therefore, we analyzed a series of 12 MPNSTs - including two cases which arose in the setting of NF1 - for molecular alterations in the p53, retinoblastoma ( Rb), and PTEN tumor suppressor genes. Furthermore, the immunohistochemical expression of p53, RB, and PTEN protein was examined in these tumors. One mutation (8%), an A to T transversion leading to an amino acid exchange, was found in exon 5 of the p53 gene in a sporadic MPNST. In two other sporadic tumors (20%), loss of heterozygosity (LOH) of the p53 gene occurred. Nuclear overexpression of p53 protein was observed in ten tumors (83%). Loss of RB protein expression was seen in two MPNSTs (17%), and LOH of the Rb gene was detected in four tumors (44%), including the two NF1-associated MPNSTs, one of them showing concomitant loss of RB protein expression. No mutation in the PTEN gene was detected, and cytoplasmic immunoreactivity for the PTEN protein was maintained in eight MPNSTs (67%). We suggest that alterations in the p53 and RB pathway, both are essential in controlling the cell-cycle progression, are critical points in the tumorigenesis of sporadic and NF1-associated MPNSTs, whereas the PTEN gene seems to play no significant role in this process. PMID: 12070601 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 16: J Neuropathol Exp Neurol. 2001 Sep;60(9):917-20. Loss of NF1 alleles distinguish sporadic from NF1-associated pilocytic astrocytomas. Kluwe L, Hagel C, Tatagiba M, Thomas S, Stavrou D, Ostertag H, von Deimling A, Mautner VF. Department of Neurosurgery, University Hospital Eppendorf, Hamburg, Germany. Pilocytic astrocytomas classified as WHO grade I typically arise in childhood and upon complete surgical removal carry a favorable prognosis. Children with neurofibromatosis 1 (NF1) have a vastly increased risk for pilocytic astrocytomas, especially for those of the optic nerve. Using 4 intragenic NF1 microsatellite markers, we examined losses of NF1 alleles on the long arm of chromosome 17 in 12 NF1-associated and 25 sporadic pilocytic astrocytomas. The TP53 gene region on the short arm of chromosome 17 was also examined in these tumors using 3 markers. Loss of 1 NF1 allele was detected in 11 of 12 (92%) informative NF1-associated pilocytic astrocytomas. In contrast, only 1 of 24 informative (4%) sporadic pilocytic astrocytomas exhibited allelic loss in the NF1 region. Among the 11 NF1-associated tumors with NF1 loss, 5 had also lost alleles on 17p. The high rate of NF1 allele loss in NF1-associated pilocytic astrocytomas suggests a tumor initiating or promoting action of the NF1 gene in these patients. On the other hand, the much lower rate of NF1-allele loss in sporadic pilocytic astrocytomas argues for only minor importance of NF1 in that patient group. The present data support different mechanisms in the formation of NF1-associated and sporadic pilocytic astrocytomas. PMID: 11556548 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 17: J Clin Endocrinol Metab. 2001 Aug;86(8):3948-57. Germline RET 634 mutation positive MEN 2A-related C-cell hyperplasias have genetic features consistent with intraepithelial neoplasia. Diaz-Cano SJ, de Miguel M, Blanes A, Tashjian R, Wolfe HJ. Department of Pathology, Tufts University-New England Medical Center, Boston, Massachusetts 02111, USA. s.j.diaz-cano@mds.qmw.ac.uk C-cell hyperplasias are normally multifocal in multiple endocrine neoplasia type 2A. We compared clonality, microsatellite pattern of tumor suppressor genes, and cellular kinetics of C-cell hyperplasia foci in each thyroid lobe. We selected 11 females from multiple endocrine neoplasia type 2A kindred treated with thyroidectomy due to hypercalcitoninemia. C-cell hyperplasia foci were microdissected for DNA extraction to analyze the methylation pattern of androgen receptor alleles and microsatellite regions (TP53, RB1, WT1, and NF1). Consecutive sections were selected for MIB-1, pRB1, p53, Mdm-2, and p21WAF1 immunostaining, DNA content analysis, and in situ end labeling. Appropriate tissue controls were run. Only two patients had medullary thyroid carcinoma foci. Nine informative C-cell hyperplasia patients showed germline point mutation in RET, eight of them with the same androgen receptor allele preferentially methylated in both lobes. C-cell hyperplasia foci showed heterogeneous DNA deletions revealed by loss of heterozygosity of TP53 (12 of 20), RB1 (6 of 14), and WT1 (4 of 20) and hypodiploid G0/G1 cells (14 of 20), low cellular turnover (MIB-1 index 4.5%, in situ end labeling index 0.03%), and significantly high nuclear area to DNA index ratio. MEN 2A (germline point mutation in RET codon 634) C-cell hyperplasias are monoclonal and genetically heterogeneous and show down-regulated apoptosis, findings consistent with an intraepithelial neoplasia. Concordant X-chromosome inactivation and interstitial gene deletions suggest clone expansions of precursors occurring at a point in embryonic development before divergence of each thyroid lobe and may represent a paradigm for other germline mutations. PMID: 11502837 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 18: J Clin Pathol. 2001 Aug;54(8):631-6. Malignant peripheral nerve sheath tumour arising within neurofibroma. An immunohistochemical analysis in the comparison between benign and malignant components. Watanabe T, Oda Y, Tamiya S, Masuda K, Tsuneyoshi M. Department of Anatomic Pathology, Pathological Sciences, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan. AIMS: To compare the expression of immunohistochemical variables between benign and malignant components of malignant peripheral nerve sheath tumour (MPNST) arising within neurofibroma. METHODS: Eight cases of MPNST arising within a neurofibroma, associated with neurofibromatosis type 1 (NF1), were studied. The areas of MPNST and neurofibroma were compared immunohistochemically with regard to the expression of proliferative activity (MIB-1), growth factors, p53, bcl-2, neural cell adhesion molecule (N-CAM), and CD34. RESULTS: The expression of transforming growth factor beta 1 (TGF-beta 1), TGF-beta receptor type II, hepatocyte growth factor alpha (HGF-alpha), c-met, p53, and N-CAM was higher in the areas of MPNST than in the neurofibromatous areas in four, five, five, eight, five, and three of the eight cases, respectively. CD34 expression was lower in the areas of MPNST than in the neurofibroma areas in three of the eight cases. CONCLUSIONS: On the basis of these findings, TGF-beta 1, HGF-alpha, and p53 might be involved in the malignant transformation of neurofibroma to MPNST. PMID: 11477120 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 19: Pathol Int. 2001 Jul;51(7):570-7. Neurofibromatosis type 1-associated unusual pleomorphic astrocytoma displaying continual malignant progression. Yokoo H, Kamiya M, Sasaki A, Hirato J, Nakazato Y, Kurachi H. First Department of Pathology, Gunma University School of Medicine, Maebashi, Japan. yokoo@med.gunma-u.ac.jp Patients with neurofibromatosis type 1 (NF1) often have gliomas as a complication, most of which are benign pilocytic astrocytomas which have arisen in optic pathways. In the present case, a 17-year-old girl (at death) with stigmata of NF1, initially had a bulky tumor mass in the left thalamus, developing into the lateral ventricle, at 13 years of age. Partially resected tissue samples showed pleomorphic astrocytoma with abundant xanthoma cells and degenerative structures such as Rosenthal fibers (RF) and eosinophilic granular bodies. Fine eosinophilic granules identical to RF, both immunophenotypically and ultrastructurally, were also seen. The residual tumor was subtotally resected 6 months later, and the tumor histology was essentially similar as before, accompanying the regenerative structures; this was believed to be a good prognostic indicator. However, several anaplastic features such as mitosis, necrosis and vascular proliferation appeared even in areas rich in the regenerative structures. After a 2-year, disease-free interval, multiple tumor relapse occurred in June 1997. Partially resected tumor tissues were composed of monotonous small anaplastic cells with prominent proliferative activity. Surprisingly, the tumor cells had retained eosinophilic granules within the cell bodies. Postoperative chemotherapy with procarbazine, MCNU and vincristine (PCV) suppressed the residual tumor dramatically, but the regrowing tumor finally became uncontrollable, leading to the patient's death. TP53 mutation was not detected, while p27 immunopositivity was constantly high during malignant progression, suggesting acquisition of proliferative activity to overcome p53 and p27 inhibitory functions. A review of previously published reports failed to reveal any cases of this type. Publication Types: Case Reports PMID: 11472572 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 20: Arch Dermatol. 2001 Jul;137(7):908-13. Malignant peripheral nerve sheath tumors associated with neurofibromatosis type 1: a clinicopathologic and molecular study of 17 patients. Leroy K, Dumas V, Martin-Garcia N, Falzone MC, Voisin MC, Wechsler J, Revuz J, Creange A, Levy E, Lantieri L, Zeller J, Wolkenstein P. Department of Dermatology, Henri-Mondor Hospital, F-94010 Creteil CEDEX, France. OBJECTIVE: To identify potential prognostic factors and criteria for early detection of malignant peripheral nerve sheath tumors associated with neurofibromatosis type 1 (NF1). DESIGN: Retrospective study of malignant peripheral nerve sheath tumors in a cohort of 395 patients with NF1 followed up between October 1, 1988, and January 1, 1999; review of the clinical and histological characteristics of treatment and course; and analysis of p53 mutations and overexpression in tumors. SETTING: Teaching hospital referral neurofibromatosis center for adults. PATIENTS: Seventeen patients with NF1 (9 males and 8 females). Mean +/- SD patient age at diagnosis was 32 +/- 14 years. MAIN OUTCOME MEASURES: (1) Clinical symptoms, (2) comparison of p53 mutations and overexpression in benign vs malignant tumors; and (3) median survival. RESULTS: Twelve patients had high-grade tumors. All tumors except 1 developed on preexisting nodular or plexiform neurofibromas. Pain and enlarging mass were the first and predominant signs. None of the benign tumors displayed significant p53 staining or p53 mutations. Six of 12 malignant tumors significantly overexpressed p53, and 4 of 6 harbored p53 missense mutations. Median survival was 18 months overall, 53 months in peripheral locations, and 21 months in axial locations. CONCLUSIONS: Malignant peripheral nerve sheath tumors are highly aggressive in NF1. They mostly arise from plexiform or nodular neurofibromas. Investigations and deep biopsy of painful and enlarging nodular or plexiform neurofibromas should be considered in patients with NF1. Late appearance of p53 mutations and overexpression precludes their use as predictive markers of malignant transformation. PMID: 11453810 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 21: Lab Invest. 2001 Jun;81(6):833-44. Rb and TP53 pathway alterations in sporadic and NF1-related malignant peripheral nerve sheath tumors. Birindelli S, Perrone F, Oggionni M, Lavarino C, Pasini B, Vergani B, Ranzani GN, Pierotti MA, Pilotti S. Pathology and Cytopathology Unit, Istituto Nazionale per lo Studio e la Cura dei Tumori, Milan, Italy. SUMMARY: Karyotypic complexities associated with frequent loss or rearrangement of a number of chromosome arms, deletions, and mutations affecting the TP53 region, and molecular alterations of the INK4A gene have been reported in sporadic and/or neurofibromatosis type I (NF1)-related malignant peripheral nerve sheath tumors (MPNSTs). However, no investigations addressing possible different pathogenetic pathways in sporadic and NF1-associated MPNSTs have been reported. This lack is unexpected because, despite similar morphologic and immunophenotypic features, NF1-related cases are, by definition, associated with NF1 gene defects. Thus, we investigated the occurrence of TP53 and p16(INK4A) gene deregulation and the presence of microsatellite alterations at markers located at 17p, 17q, 9p21, 22q, 11q, 1p, or 2q loci in MPNSTs and neurofibromas either related (14 cases) or unrelated (14 cases) to NF1. Our results indicate that, in MPNSTs, p16(INK4A) inactivation almost equally affects both groups. However, TP53 mutations and loss of heterozygosity involving the TP53 locus (43% versus 9%), and p53 wild type overexpression, related or not to mdm2 overexpression (71% versus 25%), seem to mainly be restricted to sporadic MPNSTs. In NF1-associated MPNSTs, our microsatellite results are consistent with the occurrence of somatic inactivation by loss of heterozygosity of the second NF1 allele. PMID: 11406645 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 22: Glia. 2001 Mar 15;33(4):314-23. Neurofibromatosis 1 (NF1) heterozygosity results in a cell-autonomous growth advantage for astrocytes. Bajenaru ML, Donahoe J, Corral T, Reilly KM, Brophy S, Pellicer A, Gutmann DH. Department of Neurology, Washington University School of Medicine, 860 S. Euclid Avenue, St. Louis, MO 63110, USA. Individuals with neurofibromatosis 1 (NF1) develop low-grade astrocytomas at an increased frequency. To gain insight into the function of the Nf1 gene product as a growth regulator for astrocytes, we examined mice heterozygous for a targeted Nf1 mutation. In our previous studies, we demonstrated increased numbers of proliferating astrocytes in Nf1 heterozygote (Nf1+/-) mice in vivo. We now show that cultured Nf1+/- astrocytes exhibit a cell-autonomous growth advantage in vitro associated with increased p21-ras pathway activation. Furthermore, we demonstrate that Nf1+/-;wild-type N-ras mice have a similar astrocyte growth advantage in vitro and in vivo as either oncogenic N-ras or Nf1+/-; oncogenic N-ras mice. Lastly, mice heterozygous for targeted defects in both Nf1 and p53 as well as Nf1 and Rb exhibit 3- and 2.5-fold increases in astrocyte proliferation in vivo, respectively, suggesting that abnormalities in Nf1- and p53/Rb-regulated pathways cooperate in the heterozygous state to confer a growth advantage for brain astrocytes. Collectively, these results provide evidence for a cell-autonomous growth advantage in Nf1+/- astrocytes and suggest that some of the brain pathology in individuals with NF1 might result from reduced, but not absent, NF1 gene function. Copyright 2001 Wiley-Liss, Inc. PMID: 11246230 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 23: Genes Chromosomes Cancer. 2001 Feb;30(2):202-6. Biallelic inactivation of TP53 rarely contributes to the development of malignant peripheral nerve sheath tumors. Lothe RA, Smith-Sorensen B, Hektoen M, Stenwig AE, Mandahl N, Saeter G, Mertens F. Department of Genetics, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway. About 10% of the patients with neurofibromatosis type 1 (NF1) develop malignant peripheral nerve sheath tumors (MPNSTs), accounting for half of all MPNST cases. Several nonrandom chromosomal aberrations have been found, but the target genes remain mostly unrecognized. Mutations in the NF1 and TP53 genes have been found in some MPNSTs, and recent data from mouse models support a synergistic effect of these two genes in the development of MPNST. In the present study, we have analyzed 16 MPNSTs, including 11 from patients with NF1 and 5 sporadic cases, for mutations in the coding sequence of the TP53 gene (exons 2-11). We applied denaturing gradient gel electrophoresis and modifications of this technique for analyses of 12 genomic fragments, followed by direct sequencing for identification of the mutated base(s). None of the MPNSTs revealed mutations. The detection of control mutants for each fragment analyzed, the high sensitivity of the technique, the detection of polymorphisms in some samples, and the high content of tumor tissue in the biopsies imply that false negatives are highly unlikely. Although we cannot exclude that deletions including large parts of the gene remain undetected by the mutation analyses, previous comparative genomic hybridization (CGH), cytogenetic banding analysis, and/or loss of heterozygosity studies on 14 of the cases included here had revealed 17p deletions in only three. We thus conclude that TP53 biallelic inactivation is rare in MPNST, and that the potential impact of an altered TP53 pathway on the malignant transformation of a neurofibroma into an MPNST may more frequently occur by changes in other components of that pathway. Copyright 2000 Wiley-Liss, Inc. PMID: 11135438 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 24: Nat Genet. 2000 Sep;26(1):109-13. Nf1;Trp53 mutant mice develop glioblastoma with evidence of strain-specific effects. Reilly KM, Loisel DA, Bronson RT, McLaughlin ME, Jacks T. Department of Biology and Center for Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA. Astrocytomas are the leading cause of brain cancer in humans. Because these tumours are highly infiltrative, current treatments that rely on targeting the tumour mass are often ineffective. A mouse model for astrocytoma would be a powerful tool for dissecting tumour progression and testing therapeutics. Mouse models of astrocytoma have been designed to express oncogenic proteins in astrocytes, but have had limited success due to low tumour penetrance or limited tumour progression. We present here a mouse model of astrocytomas involving mutation of two tumour-suppressor genes, Nf1 and Trp53. Humans with mutations in NF1 develop neurofibromatosis type I (NF1) and have increased risk of optic gliomas, astrocytomas and glioblastomas. The TP53 tumour suppressor is often mutated in a subset of astrocytomas that develop at a young age and progress slowly to glioblastoma (termed secondary glioblastomas, in contrast to primary glioblastomas that develop rapidly de novo). This mouse model shows a range of astrocytoma stages, from low-grade astrocytoma to glioblastoma multiforme, and may accurately model human secondary glioblastoma involving TP53 loss. This is the first reported mouse model of astrocytoma initiated by loss of tumour suppressors, rather than overexpression of transgenic oncogenes. PMID: 10973261 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 25: Genes Chromosomes Cancer. 2000 Aug;28(4):425-31. Chromosome 17 loss-of-heterozygosity studies in benign and malignant tumors in neurofibromatosis type 1. Rasmussen SA, Overman J, Thomson SA, Colman SD, Abernathy CR, Trimpert RE, Moose R, Virdi G, Roux K, Bauer M, Rojiani AM, Maria BL, Muir D, Wallace MR. Department of Pediatrics, Division of Genetics, University of Florida College of Medicine, Gainesville, Florida, USA. Neurofibromatosis type 1 (NF1) is a common autosomal dominant condition characterized by benign tumor (neurofibroma) growth and increased risk of malignancy. Dermal neurofibromas, arising from superficial nerves, are primarily of cosmetic significance, whereas plexiform neurofibromas, typically larger and associated with deeply placed nerves, extend into contiguous tissues and may cause serious functional impairment. Malignant peripheral nerve sheath tumors (MPNSTs) seem to arise from plexiform neurofibromas. The NF1 gene, on chromosome segment 17q11.2, encodes a protein that has tumor suppressor function. Loss of heterozygosity (LOH) for NF1 has been reported in some neurofibromas and NF1 malignancies, but plexiform tumors have been poorly represented. Also, the studies did not always employ the same markers, preventing simple comparison of the frequency and extent of LOH among different tumor types. Our chromosome 17 LOH analysis in a cohort of three tumor types was positive for NF1 allele loss in 2/15 (13%) dermal neurofibromas, 4/10 (40%) plexiform neurofibromas, and 3/5 (60%) MPNSTs. Although the region of loss varied, the p arm (including TP53) was lost only in malignant tumors. The losses in the plexiform tumors all included sequences distal to NF1. No subtle TP53 mutations were found in any tumors. This study also reports the identification of both NF1 "hits" in plexiform tumors, further supporting the tumor suppressor role of the NF1 gene in this tumor type. PMID: 10862051 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 26: J Cell Biochem. 2000 Apr;78(1):1-7. Biochemical characterization of a nuclear factor that binds to NF1-like elements in the rat p53 promoter. Lee M, Yu S, Park J. Department of Chemistry, Seoul National University, Seoul 151-742, Korea. We previously reported that two nuclear factor 1-like elements mediated the transcription of the rat p53 gene. A 40-kDa protein was shown to bind to these elements, which was different from common NF1 family proteins. In this study, the biochemical properties of the 40-kDa binding protein were investigated. The metal ion dependency of the protein was examined with various chelators; the protein was proved to require Mg(2+) for maximum DNA-binding activity. The binding protein was highly resistant to ionic strength and denaturant. The protein-DNA complex was reduced at high NaCl concentration, but residual DNA-binding activity remained. Even 2 M urea did not completely eliminate the formation of protein-DNA complex. DNA-binding activity of the protein was also stable at high temperature. Treatment of the protein-DNA complex with increasing concentrations of proteinase K or trypsin demonstrated the existence of a protease-resistant DNA-bound core. These biochemical properties provide new insight into the 40-kDa NF1-like nuclear factor. Copyright 2000 Wiley-Liss, Inc. PMID: 10797561 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 27: Lab Invest. 2000 Mar;80(3):279-89. Molecular evolution and intratumor heterogeneity by topographic compartments in muscle-invasive transitional cell carcinoma of the urinary bladder. Diaz-Cano SJ, Blanes A, Rubio J, Matilla A, Wolfe HJ. Department of Pathology, St Bartholomew's and the Royal London School of Medicine and Dentistry, United Kingdom. s.j.diaz-cano@mds.qmw.ac.uk Superficial transitional cell carcinomas (TCC) of the urinary bladder have been shown to be monoclonal. However, no combined study of clonality and tumor suppressor genes (TSG) is available to date for muscle-invasive TCC. Forty-four muscle-invasive TCC of the urinary bladder selected from women were included in this study. Tumor cells located above and below the muscularis mucosa zone were systematically microdissected and used for DNA extraction. Hha-I digested and undigested samples were used to study the methylation pattern of androgen receptor alleles and undigested samples were used for microsatellite analysis of TSG (TP53, RB1, WT1, and NF1). Both loss of heterozygosity (LOH) and single nucleotide polymorphism (SNP) analyses were performed using optimized denaturing gradient gel electrophoresis. The expression of p53, pRB, and p21WAF1 was assessed by immunohistochemistry. Appropriate controls were run in every case. All except two TCC showed a monoclonal pattern with the same allele inactivated in both compartments. Microsatellite analysis of TSG revealed the same LOH/SNP pattern in both tumor compartments in 30 cases (involving more than 1 TSG locus in 8) and genetic heterogeneity in 14 cases. From the latter group, 9 cases expressed more genetic changes in the deep compartment (involving TP53 gene in all cases, WT1 gene in 2, and NF1 in 1), whereas in 4 cases the superficial compartment showed more genetic changes (three involving NF1 and one involving both RB and TP53). No statistical difference in the immunoexpression was detected, although it tended to be higher in the superficial compartment than in the deep compartment. These concordant data in polymorphic DNA regions indicate that bladder-muscle-invasive TCC are monoclonal proliferations with homogeneous tumor cell selection. Heterogeneous tumor cell selection by topography defined two different genetic compartments: superficial, NF1-defective, and deep, TP53-defective. No differences in the immunohistochemical expression were observed, precluding a more extensive clinical application. PMID: 10744064 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 28: Mol Biol Rep. 1999 Dec;26(4):223-30. Differential binding of NF1 transcription factor to P53 gene promoter and its depletion in human breast tumours. Nayak BK, Das BR. Molecular Biology Division, Institute of Life Sciences, Bhubaneswar, India. Different transcription factors activate and repress the p53 gene expression. Recently, a tissue specific binding of NF1/YY1 to p53 promoter has been reported and further, it has been demonstrated that NF1/YY1 activates p53 promoter activity. The deregulated expression of p53 appears to be a central feature of malignant transformation and the basis of this deregulation is not well defined. Hence, an attempt has been made to know the binding of NF1/YY1 to p53 promoter taking breast tumour as a model system. Results have indicated a differential binding of NF1 to p53 promoter and a depletion or low level of NF1 in majority of breast tumour samples. Further, a correlation between NF1 and p53 has indicated the presence of p53 RNA even without NF1. Hence it is assumed that p53 expression is not NF1-dependent in breast tumours. However, the results clearly demonstrate a deregulation of NF1 transcription factor in breast tumours. PMID: 10634504 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 29: Science. 1999 Dec 10;286(5447):2176-9. Mouse tumor model for neurofibromatosis type 1. Vogel KS, Klesse LJ, Velasco-Miguel S, Meyers K, Rushing EJ, Parada LF. Center for Developmental Biology and Department of Pathology, University of Texas Southwestern Medical Center, 6000 Harry Hines Blvd., Dallas, TX 75235-9133, USA. Neurofibromatosis type 1 (NF1) is an autosomal dominant disorder characterized by increased incidence of benign and malignant tumors of neural crest origin. Mutations that activate the protooncogene ras, such as loss of Nf1, cooperate with inactivating mutations at the p53 tumor suppressor gene during malignant transformation. One hundred percent of mice harboring null Nf1 and p53 alleles in cis synergize to develop soft tissue sarcomas between 3 and 7 months of age. These sarcomas exhibit loss of heterozygosity at both gene loci and express phenotypic traits characteristic of neural crest derivatives and human NF1 malignancies. PMID: 10591653 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 30: Science. 1999 Dec 10;286(5447):2172-6. Mouse models of tumor development in neurofibromatosis type 1. Cichowski K, Shih TS, Schmitt E, Santiago S, Reilly K, McLaughlin ME, Bronson RT, Jacks T. Department of Biology and Center for Cancer Research and Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. Neurofibromatosis type 1 (NF1) is a prevalent familial cancer syndrome resulting from germ line mutations in the NF1 tumor suppressor gene. Hallmark features of the disease are the development of benign peripheral nerve sheath tumors (neurofibromas), which can progress to malignancy. Unlike humans, mice that are heterozygous for a mutation in Nf1 do not develop neurofibromas. However, as described here, chimeric mice composed in part of Nf1-/- cells do, which demonstrates that loss of the wild-type Nf1 allele is rate-limiting in tumor formation. In addition, mice that carry linked germ line mutations in Nf1 and p53 develop malignant peripheral nerve sheath tumors (MPNSTs), which supports a cooperative and causal role for p53 mutations in MPNST development. These two mouse models provide the means to address fundamental aspects of disease development and to test therapeutic strategies. PMID: 10591652 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 31: Biochem Cell Biol. 1999;77(3):209-14. A 40-kDa NF1-like protein, not YY1, binds to the rat p53 promoter for transactivation in various rat organs. Lee M, Song H, Yu S, Lee K, Park JS. Department of Chemistry, Seoul National University, Korea. Two recognition motifs of a 40-kDa NF1-like protein were previously identified in the rat p53 promoter. One is located between -296 and -312 (NF1-like element 1) and the other between -195 and -219 (NF1-like element 2). The latter one was also identified as a NF1/YY1 recognition motif in the human p53 promoter. NF1 or YY1 binds to the motif and regulates the expression of the human p53 gene in a tissue-specific manner. In this study, we investigated the binding protein for NF1-like element 2 in various rat tissues. Unlike the human p53 transcription, an NF1-like protein, not YY1, bound to the motif in every tested tissue: thymus, kidney, and spleen. In vitro transcription assay also confirmed that the NF1-like protein regulated the p53 transcription in rat spleen, although the human p53 transcription was regulated by YY1 in that organ. The molecular mass of the binding protein was determined to be 40 kDa, which was the same as that of the NF1-like protein identified in liver. Therefore, the 40-kDa NF1-like protein may be a universal transcription regulator for the rat p53 gene. PMID: 10505791 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 32: Cancer Genet Cytogenet. 1999 Aug;113(1):65-9. Allelic loss of the NF1 gene in NF1-associated plexiform neurofibromas. Kluwe L, Friedrich RE, Mautner VF. Department of Neurosurgery, University Hospital Hamburg-Eppendorf, Germany. Neurofibromatosis 1 (NF1) is an autosomal dominant disorder with a complex variety of clinical symptoms. Genetic alteration of the NF1 gene on 17q11.2 is the disease. Neurofibromas of the peripheral nervous system are one main manifestation. A variant of neurofibroma is the plexiform neurofibroma which can be found in about 30% of NF1-patients, often causing severe clinical symptoms. In this study, we examined 14 such tumors from 10 NF1-patients for allele loss of the NF1 gene (LOH: loss of heterozygosity) using four intragenic polymorphic markers. Loss of heterozygosity was found in eight tumors from five patients, and suspected in one additional tumor from another patient. This finding suggests that loss of the second allele, and thus inactivation of both alleles of the NF1 gene, is associated with the development of plexiform neurofibromas. The 14 plexiform neufibromas were also examined for mutation in the TP53 gene by screening exons 5 through 8 using temperature gradient gel electrophoresis. No mutation was found in any of the tumors. PMID: 10459349 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 33: Hum Pathol. 1999 Aug;30(8):984-8. Molecular analysis of malignant triton tumors. Strauss BL, Gutmann DH, Dehner LP, Hirbe A, Zhu X, Marley EF, Liapis H. Department of Pathology, Washington University School of Medicine, St. Louis, MO 63112, USA. Triton tumors are rare variants of malignant peripheral nerve sheath tumor (MPNST) with muscle differentiation, often seen in patients with neurofibromatosis 1 (NF1). Individuals affected with NF1 harbor mutations in the NF1 tumor suppressor gene and develop neurofibromas and MPNSTs. The NF1 gene is expressed in Schwann cells and its expression is lost in schwannian neoplasms, suggesting a role in malignant development. Separately, there is evidence that p53 suppressor gene mutations are involved in MPNSTs. To determine the role of the NF1 and p53 genes in the development of the malignant Triton tumor we examined 2 such tumors, 1 from a 3-year-old boy without clinical manifestations of NF1 and another from a 24-year-old man with NF1. Histological analysis of these tumors showed both neural and muscle differentiation with S-100 and desmin immunoreactivity, respectively. Reverse transcribed RNA polymerase chain reaction (RT-PCR) of NF1 mRNA showed NF1 expression in the sporadic tumor. Strong nuclear immunoreactivity for p53 was observed throughout the malignant population in both tumors. This was confirmed by loss of heterozygosity for p53 in the non-NF1 patient, suggesting that p53 is involved in both hereditary and sporadic Triton tumors. The finding of preserved NF1 gene expression in the non-NF1-related Triton tumor suggests that different genetic events predispose to the development of this rare neoplasm in sporadic cases. Publication Types: Case Reports PMID: 10452514 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 34: Cytogenet Cell Genet. 1999;84(3-4):161-3. Comparative FISH-mapping of six expressed gene loci to river buffalo and sheep chromosomes. Iannuzzi L, Gallagher DS Jr, Di Meo GP, Yang Y, Womack JE, Davis SK, Taylor JF. National Research Council (CNR), IABBAM, Naples, Italy. Six expressed gene loci (NF1, CRYB1, CHRNB1, TP53, P4HB and GH1), recently assigned to cattle chromosome 19 by both radiation hybrid analysis and FISH-mapping, were comparatively FISH-mapped to river buffalo chromosome (BBU) 3p and sheep chromosome (OAR) 11, extending the physical map in these two important bovids. The six loci mapped to the same homoeologous chromosome bands of BBU 3p and OAR 11, and their gene order was centromere-NF1-CRYB1-CHNRB1-TP53-(GH1, P4HB). PMID: 10393419 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 35: Pediatr Dev Pathol. 1999 Jul-Aug;2(4):377-84. p53 and Ki-67 proliferating cell nuclear antigen in benign and malignant peripheral nerve sheath tumors in children. Liapis H, Marley EF, Lin Y, Dehner LP. Lauren V. Ackerman Laboratory of Surgical Pathology, Barnes-Jewish and St. Louis Children's Hospitals, and Department of Pathology, Washington University, 1 Barnes-Jewish Hospital Plaza, Suite 300B, St. Louis, MO 63110, USA. Malignant peripheral nerve sheath tumors (MPNSTs) are uncommon soft tissue tumors. In children with neurofibromatosis 1 (NF1), a MPNST often arises in a pre-existing neurofibroma, or may represent an initial manifestation without other obvious stigmata of the disease. The development of MPNSTs may be associated with instability of the p53 tumor suppressor gene since it is the most frequent genetic abnormality in soft tissue sarcomas. To assess the presence of p53 accumulation in MPNSTs and its correlation with clinical and pathologic features, we studied 12 neurofibromas (NFs), including 4 tumors with cellular features (one congenital) and 10 MPNSTs. Six MPNSTs were associated with NF1, all of which developed within a plexiform neurofibroma. Cell proliferation evaluated with an antibody to Ki-67 and nuclear p53 staining were both detected by immunohistochemistry. We found p53 positivity in 60% of MPNSTs. All NFs except the congenital tumor were p53 immunonegative (P < 0.01). Rare p53-positive nuclei were detected in the transitional zone in two of six MPNSTs arising in plexiform NFs. Ki-67 distinguished the NFs from MPNSTs (P < 0.005). Half of the NF1 patients with p53-positive MPNSTs developed recurrence or metastases or developed a second malignancy within 2 years of diagnosis, whereas patients with p53-positive sporadic MPNSTs were free of disease 1 to 7 years later. We found p53 accumulation more frequently in NF1-associated MPNSTs. p53 mutations may be an additional biologic factor to account for the poor prognosis in these tumors. PMID: 10347283 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 36: Biochem Mol Biol Int. 1999 Mar;47(3):427-34. In vitro transcription assay with the purified 40kDa NF1-like protein binding to the rat p53 promoter. Lee M, Song H, Lee K, Park JS. Department of Chemistry, Seoul National University, Korea. The rat p53 promoter has several potential transcription factor-recognition motifs. They include NF1-like, bHLH family, and AP1-like proteins binding sites. The binding protein to NF1-like motif was previously identified. The protein has about 40kDa of molecular mass, which is smaller than that of NF1. Anti-NF1 polyclonal antibody does not recognize the protein. In this study, we isolated the 40kDa protein by sequence-specific DNA affinity chromatography. The isolated protein was assayed by DNase I footprinting analysis. To determine the transactivation effect of the protein, in vitro transcription with the purified 40kDa protein was carried out. After the addition of the purified 40kDa protein into the transcription reaction mixture, the transcription level of the p53 promoter was increased. This suggests that the 40 kDa NF1-like protein is a transcription activator for the rat p53 gene. PMID: 10204079 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 37: Oncogene. 1999 Jan 28;18(4):987-93. Multiple target sites of allelic imbalance on chromosome 17 in Barrett's oesophageal cancer. Dunn J, Garde J, Dolan K, Gosney JR, Sutton R, Meltzer SJ, Field JK. Molecular Genetics and Oncology Group, Clinical Dental Sciences, The University of Liverpool, UK. Twelve Barrett's adenocarcinomas have been analysed for the occurrence of allelic imbalance (LOH) on chromosome 17 using 41 microsatellite markers. This study provides evidence for 13 minimal regions of LOH, six on 17p and seven on 17q. Four of these centre in the vicinity of the known tumour suppressor genes (TSGs) TP53 (17p13.1), NFI (17q11.2), BRCA1 (17q21.1), and a putative TSG (17p13.3). The tumours all displayed relatively small regions of LOH (1-10 cM), and in several tumours extensive regions of LOH were detected. One tumour displayed only two very small regions of LOH; 17p11.2 and 17p13.1. The frequency of allelic imbalance has been calculated based on the LOH encompassing only one minimal region, and based on all the LOH observations. By both evaluations the highest LOH frequencies were found for regions II (p53), III (17p13.1 centromeric to p53), IV (17p12), V (17p11.2) and VII (NF1, 17q11.2). Our data supports the existence of multiple TSGs on chromosome 17 and challenges the view that p53 is the sole target of LOH on 17p in Barrett's adenocarcinoma. PMID: 10023674 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 38: Biol Chem. 1998 Nov;379(11):1333-40. Transcription of the rat p53 gene is mediated by factor binding to two recognition motifs of NF1-like protein. Lee M, Song H, Park S, Park J. Department of Chemistry, Seoul National University, Korea. In this study we analyzed the ratp53 promoter by electrophoretic mobility shift assay (EMSA) and DNase I footprinting analysis. As a result we identified two protein binding elements (element 1: -296 to -312, element 2: -195 to -219) with sequence homology to each other. The two identified elements bind to the same kind of protein. To identify the protein binding to these elements, competition assays were carried out with double stranded oligonucleotides containing NF1, YY1, and CRE consensus motifs. Only the NF1 consensus motif competed with element 1 and 2. Element 2 is conserved between the rat, human, and mouse p53 promoters, and has an NF1 consensus motif. However, the sequences of element 1 are comparatively variable between the species. Only the element 1 region of the rat p53 promoter has partial homology to the NF1 consensus motif. This suggests that the element 1 is specific for the rat p53 gene. The molecular mass of the binding protein, determined by Southwestern blotting analysis, was 40 kDa, which is different from that of NF1. In EMSA with an anti-NF1 antibody, DNA-protein complexes were neither supershifted nor decreased. The 40 kDa protein was also detected in rat spleen and lung, but not in kidney. The binding protein was purified by sequence-specific DNA affinity chromatography and it was confirmed that the purified protein binds to the two regions. It was also proved that the identified two elements are required for basal level transcription of the rat p53 gene by in vitro transcription assay. PMID: 9865606 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 39: Anim Genet. 1998 Apr;29(2):130-4. Physical assignment of six type I anchor loci to bovine chromosome 19 by fluorescence in situ hybridization. Gallagher DS Jr, Yang YP, Burzlaff JD, Womack JE, Stelly DM, Davis SK, Taylor JF. Department of Animal Science, Texas A&M University, College Station 77843, USA. A bovine bacterial artificial chromosome (BAC) library was screened for the presence of eight type I anchor loci previously used within hybrid somatic cells and an interspecies hybrid backcross to construct a genome map of bovine chromosome 19 (BTA19). Six out of eight loci were identified in the BAC library (NF1, CRYB1, CHRNB1, TP53, GH1 and P4HB). The BACs were then used in single-colour fluorescence in situ hybridization (FISH) to assign these genes to BTA19 band locations. Gene order was determined by single-colour FISH, and was confirmed by dual-colour FISH to mitotic and meiotic chromosomes. The order, centromere-NF1-CRYB1-CHRNB1-TP53-GH1-P4HB, was in agreement with the order determined by linkage analyses. In addition, the order of CHRNB1 and TP53, previously unresolved by linkage analyses, was established. These data provide high-resolution cytogenetic anchorage of the BTA19 genome map from chromosome bands 14-22. PMID: 9699273 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 40: Mod Pathol. 1998 Jul;11(7):612-7. Plexiform neurofibroma with and without associated malignant peripheral nerve sheath tumor: a clinicopathologic and immunohistochemical analysis of 54 cases. McCarron KF, Goldblum JR. Department of Anatomic Pathology, The Cleveland Clinic Foundation, Ohio 44195, USA. Plexiform neurofibroma (PNF) is an important part of the diagnostic criteria for neurofibromatosis type 1 (NF1) and is a known precursor lesion of malignant peripheral nerve sheath tumor (MPNST). We studied the clinicopathologic features of 54 cases of PNF for which the hematoxylin- and eosin-stained slides and paraffin blocks were available and adequate clinical follow-up could be obtained. In addition, in all cases, a representative section of the PNF and, when present, MPNST, was evaluated immunohistochemically with an antibody for p53 (DO7). The cohort included 28 male patients and 26 female patients, with an age range from 4 to 79 years (mean, 27 yr). Of these 54 patients, 46 (85%) met the strict diagnostic criteria for NF1. Thirty-nine patients had PNF alone; 15 patients had an MPNST arising from the PNF (PNF/MPNST). Those patients with PNF/MPNST tended to be older (38 yr vs. 22 yr) and to have larger tumors (10.5 cm mean vs. 7.4 cm mean) than those with PNF alone. In 9 patients (23%) of 39 with PNF alone, local recurrence developed, whereas in 7 patients (47%) of 15 with PNF/MPNST, recurrent MPNST developed, and metastases developed in 3 (20%) of the 15. Immunohistochemically, only 1 case (2.5%) of 39 cases of PNF alone stained for p53. On the other hand, 12 (80%) of 15 cases of PNF/MPNST showed p53 immunoreactivity in the MPNST component, 2 of which also showed staining in the PNF areas. In conclusion, we found that the vast majority of patients with PNF met the strict diagnostic criteria for NF1. The immunohistochemical detection of intranuclear p53 protein is common in the malignant areas of PNF/MPNST but is rare in the PNF regions. The rarity of p53 staining in the PNF regions precludes its use in predicting those tumors that are likely to progress to MPNST. PMID: 9688181 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 41: Int J Cancer. 1998 Jun 10;76(6):797-800. Absence of p53 gene mutations in a tumor panel representative of pilocytic astrocytoma diversity using a p53 functional assay. Ishii N, Sawamura Y, Tada M, Daub DM, Janzer RC, Meagher-Villemure M, de Tribolet N, Van Meir EG. Department of Neurosurgery, Centre Hospitalier Universitaire Vaudois (CHUV), Lausanne, Switzerland. Although p53-gene mutations occur with significant frequency in diffuse low-grade and high-grade astrocytomas, and are postulated to play an important role in tumorigenesis in these cases, the role of the p53 gene in pilocytic astrocytomas remains unclear. Published data using DNA-based assays for p53-gene analysis in these tumors have shown contradictory results in mutation frequency (0-14%). It is not known whether these heterogeneous results stem from the biological diversity of this tumor group or from technical problems. To re-evaluate p53-gene status in pilocytic tumors, we analyzed 18 tumors chosen to represent the clinical and biological heterogeneity of this tumor type with respect to anatomical location, patient age, gender, ethnic origin (Caucasian or Japanese) and the concomitant occurrence of neurofibromatosis type 1 (NF1). All primary tumors were histologically diagnosed as pilocytic astrocytoma (WHO grade I), except for one anaplastic pilocytic astrocytoma (WHO grade III) which developed in an NF1 patient and recurred as glioblastoma multiforme (WHO grade IV). p53 mutations were detected using an assay in yeast which tests the transcriptional activity of p53 proteins synthesized from tumor mRNA-derived p53-cDNA templates. None of 18 tumors, including 3 NF1-related tumors, showed p53-gene mutations between and including exons 4 and 11. We conclude that p53-gene mutations are extremely rare findings in pilocytic astrocytomas, and are absent even in those exceptional cases in which malignant progression of such tumors has occurred. PMID: 9626343 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 42: Mol Cell Neurosci. 1998 May;11(1-2):19-28. Sympathetic neuron survival and proliferation are prolonged by loss of p53 and neurofibromin. Vogel KS, Parada LF. Center for Developmental Biology, University of Texas Southwestern Medical Center, Dallas 75235-9133, USA. kvogel@lsumc.edu The proteins encoded by the p53 and Nf1 tumor suppressor genes are involved in cell signaling and regulation of proliferation during normal development and differentiation, as well as during tumor progression. To characterize the roles of these genes in the proliferation and survival of embryonic neurons, we have used dissociated cultures of sympathetic superior cervical ganglia (SCG) isolated from p53 and Nf1 single and compound-mutant mouse embryos. We have defined a temporal window for p53 involvement in sympathetic neuron survival and proliferation. Moreover, our results indicate that cooperativity between mutations in Nf1 and p53 prolongs SCG neuron proliferation and increases the incidence of neural tube defects in compound-mutant embryos. PMID: 9608530 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 43: Pathol Biol (Paris). 1997 Sep;45(7):556-60. [Molecular abnormalities and clonality in myelodysplastic syndromes] [Article in French] Fenaux P, Preudhomme C. Service des Maladies du Sang, CHU de Lille, France. Few genes have a proven role in the pathogenesis of myelodysplastic syndromes (MDS). The most common abnormalities involve the RAS genes, most notably the N-RAS gene, and are present in 10% of cases at diagnosis and in 30% to 40% during the course of the disease. Mutations of the p53 are found in 5% to 10% of cases. Mutations of the cFMS genes are less common, abnormalities of the NF1 genes seem to occur only in children, and abnormalities of the RB genes are exceedingly rare. A few instances of t(5;12) or t(3;21) translocation have been demonstrated, and their study has provided evidence that the TEL, EVI1, MDS1, and AML1 genes are involved in some cases of MDS. The presence in MDS of recurrent chromosome 7, 5q, and 20q deletions suggests that these chromosomal segments may bear tumor suppressor genes involved in MDS. The gene(s) involved remain(s) to be identified. Clonality studies have shown that stem cell involvement usually occurs at the myeloid level and that normal multipotent stem cells persist in many patients with MDS. This opens up the promising possibility that transplantation of autologous multipotent stem cells may be an effective therapeutic approach. Publication Types: Review Review, Tutorial PMID: 9404479 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 44: Cancer. 1997 Nov 15;80(10):2013-8. p53 mutation as the second event in juvenile chronic myelogenous leukemia in a patient with neurofibromatosis type 1. Luria D, Avigad S, Cohen IJ, Stark B, Weitz R, Zaizov R. Cancer Molecular Genetics, Felsenstein Medical Research Center, Tel Aviv University, Israel. BACKGROUND: Young patients with neurofibromatosis type 1 (NF1) are at increased risk of developing various malignancies, most of which are myeloid disorders. The observed loss of NF1 allele in the myeloid malignancies of NF1 patients suggests a role of NF1 as a tumor suppressor gene. Loss of 17p was found to be quite frequent in neural crest tumors from patients with NF1, raising the possibility of p53 tumor suppressor gene involvement in other NF1-related tumors. METHODS: The authors studied mutations in the NF1 and p53 genes, using loss of heterozygosity, single strand conformation polymorphism, heteroduplex and sequencing analyses. RESULTS: An NF1 germline mutation was identified in exon 31 of a child who developed juvenile chronic myelogenous leukemia (JCML). The mutation was segregated within the proband's family. A 14bp deletion at exon 6 of the p53 gene was observed when JCML was diagnosed, and the wild-type p53 allele was lost during progression of the disease. No loss of the normal NF1 allele could be detected. CONCLUSIONS: A germline mutation in the NF1 gene and sequential inactivation of p53 alleles in the malignant clone of JCML raise the possibility of a correlation between NF1 and p53 genes in the tumorigenesis of JCML. Publication Types: Case Reports PMID: 9366306 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 45: Clin Neuropathol. 1997 Jul-Aug;16(4):220-6. Chromosome 17 allelic loss in astrocytic tumors and its clinico-pathologic implications. Muhammad AK, Yoshimine T, Maruno M, Tokiyoshi K, Takemoto O, Ninomiya H, Hayakawa T. Department of Neurosurgery, Osaka University Medical School, Japan. To prognosticate the implications of various allelic losses on chromosome 17 in the morphology and biology of astrocytic tumors, we have examined loss of heterozygosity (LOH) at 14 microsatellite loci on chromosome 17 in a series of 19 astrocytic tumors (3 astrocytomas, 5 anaplastic astrocytomas, and 11 glioblastomas). The DNA samples extracted from tumor and matched normal brain tissue were amplified by polymerase chain reaction (PCR) followed by polyacrylamide gel electrophoresis and photography under UV transillumination. The molecular genetic data were compared with immunohistochemistry performed with antibodies to glial fibrillary acidic protein (GFAP), MIB-1 and p53 protein. LOH was observed in 11/19 (58%) instances with frequent involvement of TP53, NF1, and D17S795 loci, LOH at D17S578 and D17S520 occurred in recurrent tumors exclusively. Allelic status of D17S795 in all 12 informative instances were concordant with GFAP immunoreactivity (p < 0.01, Fisher's test). p53 immunopositivity (> 25% of tumor cell nuclei) was seen in 11 (58%) tumors, of which 6 were informative of TP53 locus with 2 (33%) demonstrating LOH. The MIB-1 staining indexes in astrocytomas, anaplastic astrocytomas, and glioblastomas were 1.9 +/- 0.9, 8.4 +/- 4.0, and 17.1 +/- 7.1% (mean +/- SD), respectively, and their differences were statistically significant (p < 0.05, Student's t test). A trend of inverse relationship between patient survival and the number of tumor cell nuclei with immunohistochemically detectable p53 protein was seen in glioblastoma cases: 20.5 +/- 12.7 versus 13.7 +/- 6.3 months (mean +/- SD) in instances with > or > or = 25% positive cells, respectively. We conclude, the intriguing correlation between allelic status of D17S795 microsatellite locus and GFAP immunoreactivity suggests the possible involvement of q21.2 segment of chromosome 17 in the morphology and biology of astrocytic tumors. PMID: 9266149 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 46: Leukemia. 1997 Apr;11 Suppl 3:533-5. Genetic aberrations in the development and subsequent progression of myelodysplastic syndrome. Misawa S, Horiike S, Kaneko H, Kashima K. Third Department of Medicine, Kyoto Prefectural University of Medicine, Japan. We performed longitudinal analyses of chromosomes and studied the configuration of NRAS, TP53, NF1, and cFMS genes in 70 patients with myelodysplastic syndrome(MDS). The NRAS mutations were detected in 6 patients(9%) at codons 12 or 13. The TP53 mutations were found in 10 patients(14%) in exons 4 through 8. Longitudinal studies revealed that the NRAS mutation was a late-appearing event, while the TP53 mutations were detectable at the presentation of MDS. No patients had both NRAS and TP53 mutations, simultaneously. NF1 and cFMS genes showed any mutational event among these 70 patients. Patients with a TP53 mutation had a significantly shorter survival time than those with an NRAS mutation or those without NRAS or TP53 mutation. However, patients who showed an NRAS mutation had a shorter survival time once the mutation emerged, similar to that of patients with a TP53 mutation. PMID: 9209448 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 47: Mamm Genome. 1997 Apr;8(4):262-6. Construction of a bovine chromosome 19 linkage map with an interspecies hybrid backcross. Yang YP, Womack JE. Department of Veterinary Pathobiology and Center for Animal Genetics, Institute of Biosciences and Technology, Texas A&M University, College Station, Texas 77843, USA. Interspecific hybrid backcross animals from a Bos taurus x Bos gaurus F1 female were used to construct a linkage map of bovine Chromosome (Chr) 19. This map includes eight previously unmapped type I anchor loci, CHRNB1, CRYB1, GH1, MYL4, NF1, P4HB, THRA1, TP53, and five microsatellite markers, HEL10, BP20, MAP2C, ETH3, BMC1013, from existing linkage maps. The linkage relationship was determined to be centromere-HEL10-18.8cM-NF1-4.0cM-CRYB1-11 .2cM-(BP20, CHRNB1, TP53)-4.0cM-(MAP2C, GH1, MYL4, THRA1)-14.4cM-P4HB-11.2cM-ETH3-4. 0cM-BMC1013. It was previously revealed that bovine Chr 19 contains the largest known conserved autosomal synteny among human, bovine, and mouse. This study has shown that gene orders within this segment are not conserved among the three species. We propose structural changes in an ancestral mammalian chromosome to account for these differences. This is the first interspecific hybrid backcross used in bovine linkage studies, and it has proven to be an effective tool for incorporating bovine type I loci into the linkage map even with the small sample size presently available. This resource will facilitate the generation of comparative linkage maps that address gene order and effectively predict the locations of unmapped loci across species. PMID: 9096107 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 48: Mol Cell Biol. 1996 Oct;16(10):5933-45. YY1 and NF1 both activate the human p53 promoter by alternatively binding to a composite element, and YY1 and E1A cooperate to amplify p53 promoter activity. Furlong EE, Rein T, Martin F. Pharmacology Department, University College Dublin, Ireland. A novel transcription factor binding element in the human p53 gene promoter has been characterized. It lies about 100 bp upstream of the major reported start site for human p53 gene transcription. On the basis of DNase I footprinting studies, electromobility shift assay patterns, sequence specificity of binding, the binding pattern of purified transcription factors, effects of specific antibodies, and methylation interference analysis we have identified the site as a composite element which can bind both YY1 and NF1 in an independent and mutually exclusive manner. The site is conserved in the human, rat, and mouse p53 promoters. The occupancy of the site varies in a tissue-specific manner. It binds principally YY1 in nuclear extracts of rat testis and spleen and NF1 in extracts of liver and prostate. This may facilitate tissue-specific control of p53 gene expression. When HeLa cells were transiently transfected with human p53 promoter-chloramphenicol acetyltransferase reporter constructs, a mutation in this composite element which disabled YY1 and NF1 binding caused a mean 64% reduction in basal p53 promoter activity. From mutations which selectively impaired YY1 or NF1 binding and the overexpression of YY1 or NF1 in HeLa cells we concluded that both YY1 and NF1 function as activators when bound to this site. In transient cotransfections E1A could induce the activity of the p53 promoter to a high level; 12S E1A was threefold as efficient as 13S E1A in this activity, and YY1 bound to the composite element was shown to mediate 55% of this induction. Overexpressed YY1 was shown to be able to synergistically activate the p53 promoter with E1A when not specifically bound to DNA. Deletion of an N-terminal domain of E1A, known to be required for direct E1A-YY1 interaction and E1A effects mediated through transcriptional activator p300, blocked the E1A induction of p53 promoter activity. PMID: 8816507 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 49: Cancer Genet Cytogenet. 1996 Sep;90(2):125-9. Absence of germline mutations in exons 5-9 of the p53 gene in patients with Li-Fraumeni-like (SBLA) and familial adenomatous polyposis heritable cancer syndromes. Moore SK, Zambrano N, Lynch HT, Lipkin M, Kopelovich L. Food and Drug Administration, Center for Drug Evaluation and Research, Rockville, Maryland, USA. Although acquired mutations in the human p53 gene occur in many tumor types, germline mutations are rare. An exception is the occurrence of germline p53 mutations in a fraction of families afflicted with the Li-Fraumeni syndrome (LFS). Previous studies from our laboratory demonstrated increased levels of wild type p53 protein in skin fibroblasts (SF) of patients from heritable cancer syndrome, including familial adenomatous polyposis (FAP), neurofibromatosis type 1 (NF1), and bilateral retinoblastoma (bRB) (Kopelovich and DeLeo, 1984,1986). Here, we further address the association between germline p53 alterations and genetic predisposition to cancer in the SBLA syndrome and in FAP. DNA sequencing and single-stranded conformational polymorphism analysis (SSCP) were utilized to screen for the presence of mutations within exons 5-9 of the p53 gene in SF and in benign tumors. Thus we observed no germline mutations in exons 5-9 of the p53 gene in SF from SBLA or FAP patients, including the Gardner variant. In addition, we observed no acquired mutations in exons 5-9 of the p53 gene in benign tumors from FAP patients. In conclusion, we found no association between germline p53 mutations and SBLA or FAP. How mechanisms that involve nonmutational activation of the p53 protein might affect genetic predisposition to cancer remains to be established. PMID: 8830720 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 50: Am J Clin Pathol. 1996 Sep;106(3):282-8. Comment in: Am J Clin Pathol. 1996 Sep;106(3):271-2. p53 expression in neurofibroma and malignant peripheral nerve sheath tumor. An immunohistochemical study of sporadic and NF1-associated tumors. Halling KC, Scheithauer BW, Halling AC, Nascimento AG, Ziesmer SC, Roche PC, Wollan PC. Department of Pathology and Laboratory Medicine, Mayo Clinic, Rochester, Minnesota 55905, USA. Malignant peripheral nerve sheath tumors (MPNST) are highly malignant sarcomas arising either de novo or in transition from neurofibroma. Although relatively little is known of the molecular genetic alterations that underlie their formation, recent DNA sequencing studies have demonstrated the presence of p53 mutations in some MPNST. This tumor-suppressor gene has been implicated in the progression of a variety of human malignancies, including sarcomas. Employing the anti-p53 monoclonal antibody Do-7, this retrospective immunohistochemical study of p53 gene overexpression in MPNST found reactivity to be present in 68% and to be significant in degree in 57%. In contrast, although some degree of p53 overexpression was present in 48% of neurofibromas, none stained strongly and only 1 of the 27 (4%), a cellular example, showed significant staining. No difference in the frequency or degree of p53 staining was noted between MPNSTs from patients with or without neurofibromatosis 1. The observed overexpression of the gene product, possibly the reflection of a p53 gene mutation, suggests a role for p53 in the progression of neurofibroma to MPNST. Although the prognostic of p53 overexpression in MPNST remains to be confirmed, in the present series immunopositive tumors were associated with a shorter median patient survival (18 months) than were tumors showing no reactivity (82 months) (P = .02). PMID: 8816583 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 51: Genes Chromosomes Cancer. 1996 Jan;15(1):18-25. Apparent preferential loss of heterozygosity at TSC2 over TSC1 chromosomal region in tuberous sclerosis hamartomas. Carbonara C, Longa L, Grosso E, Mazzucco G, Borrone C, Garre ML, Brisigotti M, Filippi G, Scabar A, Giannotti A, Falzoni P, Monga G, Garini G, Gabrielli M, Riegler P, Danesino C, Ruggieri M, Magro G, Migone N. Dipartimento di Genetica, Biologia e Chimica Medica, Universita di Torino, Italy. To investigate the molecular mechanisms of tuberous sclerosis (TSC) histopathologic lesions, we have tested for loss of heterozygosity the two TSC loci (TSC1 and TSC2) and seven tumor suppressor gene-containing regions (TP53, NF1, NF2, BRCA1, APC, VHL, and MLM) in 20 hamartomas from 18 TSC patients. Overall, eight angiomyolipomas, eight giant cell astrocytomas, one cortical tuber, and three rhabdomyomas were analyzed. Loss of heterozygosity at either TSC locus was found in a large fraction of the informative patients, both sporadic (7/14) and familial (1/4). Interestingly, a statistically significant preponderance of loss of heterozygosity at TSC2 was observed in the sporadic group (P < 0.01). Among the possible explanations considered, the bias in the selection for TSC patients with the most severe organ impairment seems particularly appealing. According to this view, a TSC2 defect might confer a greater risk for early kidney failure or, possibly, a more rapid growth of a giant cell astrocytoma. None of the seven antioncogenes tested showed loss of heterozygosity, indicating that the loss of either TSC gene product may be sufficient to promote hamartomatous cell growth. Finally, the observation of loss of heterozygosity at different markers in an astrocytoma and in an angiomyolipoma from the same patient might suggest the multifocal origin of the second-hit mutation. PMID: 8824721 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 52: Int J Cancer. 1995 Jun 22;64(3):189-95. Increased expression of the NME1 gene is associated with metastasis in epithelial ovarian cancer. Leary JA, Kerr J, Chenevix-Trench G, Doris CP, Hurst T, Houghton CR, Friedlander ML. Department of Obstetrics and Gynaecology, University of Sydney, NSW, Australia. The genetic events involved in the development of metastases of epithelial ovarian cancer are largely unknown. One gene postulated to play a role in tumour metastasis suppression is NME1 (nm23-H1), and an inverse relationship between NME1 expression and metastatic potential has been observed for some solid tumours. In this study we have investigated the levels of mRNA expression of the 2 isoforms of the NME gene, NME1 and NME2. A maximum of 45 tumours samples from 33 patients were available for Northern blot analysis. We observed variable levels expression of NME1 and NME2 mRNA. The average level of NME1, but not NME2, mRNA expression was statistically higher in metastatic biopsies when compared with primary tumour biopsies. To examine the possible tumour suppressor gene role of NME1 in ovarian tumours, 76 patients were investigated by Southern blot analysis to determine the rate of allelic deletion. Allele loss at 5 other chromosome 17 loci (D17S5, TP53, NF1, D17S74, D17S4) was also evaluated for many of these 76 patients. Allele loss was observed in 22/30 (73%) informative patients at the NME1 locus. We also observed high rates of allele loss at the other loci evaluated. No correlations with clinical stage, histological subtype or patient survival were observed in either mRNA or DNA analyses. We have established that tumour progression in ovarian cancer is accompanied by over-expression of the NME1 gene; however, despite high rates of allele loss at the NME1 locus, the concept that NME1 may be a candidate tumour suppressor gene in ovarian cancer cannot be confirmed by this study. PMID: 7622307 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 53: Genomics. 1995 May 20;27(2):293-7. Human chromosome 17 comparative anchor loci are conserved on bovine chromosome 19. Yang YP, Womack JE. Department of Veterinary Pathobiology, Texas A&M University, College Station 77843, USA. Eight comparative anchor loci on human chromosome 17, TP53, CHRNB1, THRA1, CRYB1, NF1, MPO, MYL4, and P4HB, were mapped to bovine chromosome 19 using bovine x hamster and bovine x mouse hybrid somatic cell lines. This completes the synteny mapping of human chromosome 17 comparative anchor loci in cattle, all of which have been mapped to bovine chromosome 19 and mouse chromosome 11, with the exception of CSH1. It is likely that the suggested homologue of human CSH1, PL1 on cattle chromosome 23, is a not true homologue of the human gene. This study reveals the largest conserved synteny segment among human, cattle, and mouse autosomes described to date. While all of the genes mapped to cattle chromosome 19 are on human chromosome 17, genes on mouse chromosome 11 are distributed on 7 human chromosomes, supporting the hypothesis that there is greater conservation of synteny between human and bovine chromosomes than between human and mouse. PMID: 7557995 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 54: Br J Cancer. 1995 May;71(5):1070-3. Colorectal carcinomas show frequent allelic loss on the long arm of chromosome 17 with evidence for a specific target region. Leggett B, Young J, Buttenshaw R, Thomas L, Young B, Chenevix-Trench G, Searle J, Ward M. Glaxo Gastroenterology Research Laboratory, Royal Brisbane Hospital Clinical Research Centre, Bancroft Centre, Australia. Allelic loss is a common mechanism of inactivation of tumour-suppressor genes in colorectal carcinomas. A number of known or putative tumour-suppressor genes including NF1, BRCA1, NME1, NME2 and prohibitin are present on the long arm of chromosome 17, and this region has not been extensively analysed in colorectal tumours. In this study 72 colorectal carcinomas were examined for allelic loss at eight loci on chromosome 17. Allelic loss was frequent both at the p53 locus, which is known to be important in colorectal carcinoma, and also telomeric to p53 on 17p. Allelic loss continued to be present in more than 50% of cases in the pericentromeric region and on proximal 17q to the marker LEW101 (D17S40) at 17q22-23. The most telomeric markers on 17q showed lower rates of allelic loss. Analysis of cases with partial deletions which did not include the p53 locus showed a common region of overlap of the deletions centred on D17S40. This suggests the target of allelic loss on 17q is a tumour-suppressor gene in this region. PMID: 7734302 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 55: Nucleic Acids Res. 1995 Feb 25;23(4):663-9. Identification of an upstream region of the mouse p53 promoter critical for transcriptional expression. Hale TK, Braithwaite AW. John Curtin School of Medical Research, Australian National University, Canberra. We have investigated the transcription factor requirements for basal expression of the mouse p53 promoter by using a combination of reporter and electrophoretic mobility shift assays (EMSAs). We have found that only four regions of the promoter bind transcription factors in EMSAs, suggesting that these are the only important factors for basal transcription. These factors are NF1, USF, ETF-like and a novel factor which we have called PF2. Construction of promoter deletion mutants has shown that the absence of the PF2 site completely inactivates the promoter, whereas deletion of other sites, whilst reducing promoter activity, does not. We suggest that this novel transcription factor (PF2) is critical for expression of the mouse p53 promoter. PMID: 7899088 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 56: J Neuropathol Exp Neurol. 1995 Jan;54(1):65-73. Alterations at chromosome 17 loci in peripheral nerve sheath tumors. Lothe RA, Slettan A, Saeter G, Brogger A, Borresen AL, Nesland JM. Department of Genetics, Norwegian Radium Hospital, Oslo. Little is known about the molecular genetic changes in malignant peripheral nerve sheath tumors (MPNST). Inactivation of the TP53 gene in 17p has been reported in a few tumors. The MPNST is one of the manifestations of neurofibromatosis 1 (NF1), suggesting that the NF1 gene in 17q might be important. We present a study of 15 neurofibromas and MPNST from nine individuals. Seven patients had NF1, and six of these developed MPNST. Genetic alterations at nine polymorphic loci on chromosome 17 were examined. Allelic imbalance was detected only in the malignant tumors from NF1 patients (4/6). Complete loss of heterozygosity of 17q loci was found in three of these tumors, all including loci within the NF1 gene. Two of the malignant tumors also showed deletions on 17p. No mutations were detected within exon 5-8 of the TP53 in any of the MPNST, and none of them were TP53 protein-positive using immunostaining with mono- and polyclonal antibodies against TP53. The numbers of chromosome 17 present in each tumor were evaluated by use of fluorescence in situ hybridization (FISH) on interphase nuclei with a centromere-specific probe. A deviation from the disomic status of chromosome 17 was observed in two of the MPNST from NF1 patients. These results support the hypothesis of inactivation of both NF1 gene alleles during development of MPNST in patients with NF1. In contrast to other reports, we did not find evidence for a homozygous mutated condition of the TP53 gene in the same tumors. Finally, FISH analysis was in accordance with the DNA analysis in the deduction of the numbers of chromosome 17 in these tumors. PMID: 7815081 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 57: Nippon Rinsho. 1994 Dec;52(12):3319-29. [Tumor suppressor genes] [Article in Japanese] Kuchino Y. Cell fusion experiments performed by Harris et al. informed that tumor suppressor genes are inactivated in malignant cells. Inactivation of tumor suppressor genes induced by genetic alteration such as point mutation and deletion leads to disturbance in the control of cell proliferation resulting in deregulated growth of normal cells. Recently, many challenges of scientists including clinicians trying to direct the studies of tumor suppressors toward cancer therapy have been stimulated. For that purpose, it is important to understand the molecular mechanism in which change of normal phenotypes into tumor take place. In this review, recent topics on tumor suppressors such as Rb, p53, Wt1, APC, NF1, s-Myc and H19 are included to discuss their significance and function. Publication Types: Review Review, Tutorial PMID: 7853729 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 58: Br J Cancer. 1994 Nov;70(5):813-8. Frequency of allele loss of DCC, p53, RBI, WT1, NF1, NM23 and APC/MCC in colorectal cancer assayed by fluorescent multiplex polymerase chain reaction. Cawkwell L, Lewis FA, Quirke P. Centre for Cancer Studies, Research School of Medicine, University of Leeds, UK. We report here the use of multiplex fluorescent polymerase chain reaction (PCR) for quantitative allele loss detection using microsatellites with 2-5 base pair repeat motifs. Allele loss of APC, DCC, p53 and RB1 in colorectal tumours has been reported previously using a variety of methods. However, not all workers used intragenic markers. We have used microsatellite polymorphisms which map within, or are closely linked to, these tumour-suppressor gene loci in order to determine whether these loci are indeed the targets for alteration in colorectal cancer. In addition, we have assayed two other tumour-suppressor genes, WT1 and NF1, to see whether they play a role in colorectal carcinogenesis. The putative metastasis-suppressor gene, NM23, was also investigated since there have been conflicting reports about its involvement in colorectal carcinogenesis. Allele loss was detected at the DCC (29%), p53 (66%), RB1 (50%) and NF1 (14%) loci and in the APC/MCC region (50%), but not at the WT1 or NM23 loci. These rapid, and mostly gene-specific, fluorescent multiplex PCR assays for allele loss detection could be modified to devise a single molecular diagnostic test for the important lesions in colorectal cancer. PMID: 7947085 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 59: Genes Chromosomes Cancer. 1994 Aug;10(4):250-5. TP53 mutations are frequent in malignant NF1 tumors. Legius E, Dierick H, Wu R, Hall BK, Marynen P, Cassiman JJ, Glover TW. Center for Human Genetics, University Hospital Gasthuisberg, Leuven, Belgium. Neurofibromatosis type I (NFI) is a common autosomal dominant disorder with an increased risk for developing benign and malignant tumors. The NFI gene has been cloned and maps to 17q11.2, and the gene product acts as a tumor suppressor gene. Here we analyzed the role of mutations in TP53 in four malignant NFI tumors. Mutations were found in 3 out of 4 tumors. One of these mutations is a common missense mutation in codon 278 in one of the previously identified hot spots for mutations. The two other are hitherto unreported mutations, including a splice mutation of exon 3 and a nonsense mutation in exon 4. In addition, these four tumors also showed loss of heterozygosity (LOH) for markers on chromosome 17 in the region of TP53. Malignant NFI tumors are initiated by a somatic inactivation of the second NFI allele. Tumor progression, however, occurs by accumulation of additional genetic abnormalities, such as homozygous inactivation of TP53, as demonstrated in this paper. PMID: 7522538 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 60: Cancer Res. 1993 Sep 1;53(17):4053-8. Mutation of the p53 gene in neuroblastoma and its relationship with N-myc amplification. Imamura J, Bartram CR, Berthold F, Harms D, Nakamura H, Koeffler HP. University of California, School of Medicine, Los Angeles 90024. Mutation of the p53 tumor suppressor gene frequently occurs in a variety of tumors including lung, breast, gastrointestinal, and brain, as well as lymphomas-leukemias. Neuroblastoma, one of the most common solid tumors in childhood, often has amplification of the N-myc gene. We examined for mutations of the p53 tumor suppressor gene by single-strand conformational polymorphism using polymerase chain reaction products and direct sequencing method in neuroblastoma; in addition, we assessed the relationship between p53 mutation and N-myc gene amplification in the disease. Of 86 DNA samples from patients with neuroblastoma, two mutations (2%) were found in the coding region of the p53 gene. Each mutation caused a substitution of amino acid residues. One mutation was located in exon 5, and another was in exon 6. N-myc gene was amplified in 26% of the samples. No p53 mutations were found in neuroblastoma samples with N-myc amplification. In the two individuals, p53 mutations appeared as their disease became more progressive. The neurofibromatosis 1 (NF1) gene is frequently abnormal in another neural disorder, neurofibromatosis type 1; in addition, a potential mutational hot spot of NF1 at lysine at codon 1423 has been identified in several types of tumors. Using single-strand conformational polymorphism, we were unable to detect an abnormality in this region of NF1 in 50 samples of neuroblastoma. The data suggest that p53 mutations occasionally are associated with progression of neuroblastomas, and tumorigenetic influences of mutant p53 may differ from those of N-myc. PMID: 8358734 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 61: Gan To Kagaku Ryoho. 1993 Aug;20(10):1429-34. [Functions of antioncogene products] [Article in Japanese] Akiyama T. Dept. of Oncogene Research, Osaka University. Inactivation of antioncogenes result in the generation of tumor cells. Recent progress in molecular biology of antioncogenes enabled us to study the function of the products of RB, WT, p53, NF1, DCC, APC and MCC genes. Analyses of the function of these proteins will give us an insight into the mechanisms of cell transformation. PMID: 8346943 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 62: Leukemia. 1993 Jun;7(6):912-5. Sequential development of Wilms tumor, T-cell acute lymphoblastic leukemia, medulloblastoma and myeloid leukemia in a child with type 1 neurofibromatosis: a clinical and cytogenetic case report. Perilongo G, Felix CA, Meadows AT, Nowell P, Biegel J, Lange BJ. Department of Pediatrics, Children's Hospital of Philadelphia, PA 19104. In her 8 1/2 years of life, a girl with neurofibromatosis type 1 (NF1) developed four sequential primary malignant neoplasms: Wilms tumor, T-cell acute lymphoblastic leukemia, medulloblastoma and acute myeloid leukemia. The last three tumors were characterized by chromosomal abnormalities non-randomly associated with that particular disease. There was no evidence of germline p53 mutation or of mutation of p53 in the last two tumors. We hypothesize that an unusual mutation of the NF1 gene in this child promoted growth in tissues where the normal or mutated NF-1 gene product is usually silent or growth inhibitory. Publication Types: Case Reports PMID: 8388972 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 63: Pathol Res Pract. 1993 May;189(4):465-71; discussion 471-4. Genetic alterations in a malignant schwannoma from a patient with neurofibromatosis (NF1). Lothe RA, Saeter G, Danielsen HE, Stenwig AE, Hoyheim B, O'Connell P, Borresen AL. Department of Genetics, Norwegian Radium Hospital. In a patient with neurofibromatosis (von Recklinghausen disease; NF1), normal lymphocytes, five cutaneous neurofibromas, and tumour tissue from a recurrence of a malignant schwannoma were analysed for genetic alterations. Eleven DNA markers located on chromosome 17 and nine randomly chosen markers representing chromosomes 1, 2, 3, 4, 5, 6, and 11, were analysed. High resolution Giemsa banding of lymphocytes revealed no chromosomal rearrangement. The DNA from the neurofibromas were all found to have the same restricted fragment length polymorphism pattern as the constitutional DNA from the patient. In the malignant schwannoma a complete loss of one allele was found at polymorphic loci on chromosome arm 17p. One gene copy of the TP53 gene (17p13.1) and the NF1 gene (17q11.2) was lost, as was one copy of the PGA gene (11q13). No mutations were detected in the mutational hotspots of the TP53 gene. Partial losses were detected at three loci on chromosomes 1, 2 and 6, indicating a clonal variation within the tumour since histological evaluation disclosed no normal tissue in the analysed specimen. Our data indicate that the NF1 gene may function as a tumour suppressor gene, and that, either by effect of dose reduction or complete inactivation, both the NF1 gene and the TP53 gene may be critical for the progression of a neurofibroma to a malignant schwannoma. The observations made are consistent with the concept of stepwise multigenetic changes in tumour progression. Publication Types: Case Reports PMID: 8351250 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 64: Curr Opin Oncol. 1991 Jun;3(3):476-84. Pathways of oncogenesis in primary brain tumors. Steck PA, Saya H. University of Texas M.D. Anderson Cancer Center, Houston. Recent efforts have been directed at identifying and characterizing candidate tumor suppressor genes and the activities of oncogenes in primary brain tumors. The p53 gene mapping to region p13 of chromosome 17 has several characteristics as a tumor suppressor gene. The wild-type p53 protein, which is a transcriptional activator, may serve as a barrier to the progression of neoplastic processes, and alterations of p53 are involved in genesis of various cancers including astrocytomas. The NF1 gene, which is responsible for the susceptibility to neurofibromatosis type 1, has recently been isolated. This gene is assumed to play a role in the signal transduction pathway by interacting with the ras gene product. Recent observation revealed that the NF1 gene may regulate the neuronal differentiation, and the alteration in regulation of the NF1 transcript is potentially related to the progression of neuroectodermal tumors. Restriction fragment length polymorphism studies have also shown chromosomal losses associated with chromosome 9, 10 and 17. These losses of genetic material are suspected to involve loci near or at the p53 gene for chromosome 17, and neighboring the interferon genes on chromosome 9. Although no sublocalization of chromosome 10 deletions has been accomplished, all of these loci are thought to harbor tumor suppressor genes. Recent advances in oncogene research have focused on understanding the mechanisms of action of growth factors, growth factor receptors, and their substrates, particularly in glial oncogenesis. Fibroblast growth factor, epidermal growth factor, and their respective receptors are of particular interest. However, the ROS oncogene, which is expressed and rearranged in some glioma cell lines, may not be a critical factor in the development of gliomas.(ABSTRACT TRUNCATED AT 250 WORDS) Publication Types: Review PMID: 1909900 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 65: Genes Chromosomes Cancer. 1991 Jan;3(1):62-70. Molecular and cytogenetic analysis of tumors in von Recklinghausen neurofibromatosis. Glover TW, Stein CK, Legius E, Andersen LB, Brereton A, Johnson S. Department of Pediatrics, University of Michigan, Ann Arbor 48109. Von Recklinghausen neurofibromatosis (NF1) is a common autosomal dominant disorder mapped to 17q11.2 and typically characterized by the occurrence of neural crest-derived tumors. The gene has recently been cloned using reverse genetics or "positional cloning" approaches. Its function, however, remains unknown. We have performed cytogenetic and molecular analyses on 9 malignant tumors from NF1 patients to look for loss of alleles or chromosome rearrangements involving chromosome 17 to test the hypothesis that the NF1 gene acts as a recessive "tumor suppressor" gene. Loss of alleles on this chromosome was detected for 3 of 9 malignant tumors. Two peripheral nerve sheath tumors showed allele loss at informative loci on both the long and short arms of chromosome 17. In contrast, a glioblastoma with focal gliosarcoma showed loss of heterozygosity on the short arm of chromosome 17 only, and not at loci on the long arm. One nerve sheath tumor was previously shown by direct sequence analysis to have a point mutation at the TP53 locus at 17p13. These data support a role for the TP53 gene or other genes on the short arm of chromosome 17 in at least some malignancies in NF1. Six other neurofibrosarcomas showed no allele loss at informative loci on chromosome 17. Cytogenetic analysis was performed on 7 tumors, including 2 with allele loss. The two tumors with allele loss showed abnormal karyotypes while all others were normal. Southern blot and pulsed-field gel analysis using probes within or closely linked to the NF1 locus detected no gross deletions or rearrangements in the tumors studied.(ABSTRACT TRUNCATED AT 250 WORDS) PMID: 1906341 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 66: Oncogene. 1990 Sep;5(9):1285-90. Protein-binding elements in the promoter region of the mouse p53 gene. Ginsberg D, Oren M, Yaniv M, Piette J. Department of Chemical Immunology, Weizmann Institute of Science, Rehovot, Israel. p53 is a cellular protein whose expression plays a crucial role in the regulation of cell proliferation and of neoplastic processes. p53 mRNA levels in mouse fibroblasts can be elevated in response to TPA and to serum stimulation. The promoter region of the p53 gene contains a conserved element which is highly homologous to the consensus AP1 binding site (7/8 matching bases). This AP1-like site, denoted the PF1 site, confers upon a heterologous promoter ability to respond to elevated expression of c-jun. Furthermore, the PF1 site binds protein(s) in a specific and serum-induced manner. Unexpectedly, this factor is most probably not AP1, as evident from the inability of an authentic AP1 site to compete the binding efficiently, as well as from the failure of purified AP1 to bind to the PF1 site. Hence, PF1 may be a novel AP1-related transcription factor. In addition, the 5' region of the p53 gene also contains an NF1 binding site, whose location suggests a possible regulatory role. PMID: 2216454 [PubMed - indexed for MEDLINE] --------------------------------------------------------------- 67: Proc Natl Acad Sci U S A. 1990 Jul;87(14):5435-9. Chromosome 17p deletions and p53 gene mutations associated with the formation of malignant neurofibrosarcomas in von Recklinghausen neurofibromatosis. Menon AG, Anderson KM, Riccardi VM, Chung RY, Whaley JM, Yandell DW, Farmer GE, Freiman RN, Lee JK, Li FP, et al. Molecular Neurogenetics Laboratory, Massachusetts General Hospital, Boston. von Recklinghausen neurofibromatosis (NF1) is a common hereditary disorder characterized by neural crest-derived tumors, particularly benign neurofibromas whose malignant transformation to neurofibrosarcomas can be fatal. The NF1 gene has been mapped to a small region of chromosome 17q, but neither the nature of the primary defect nor the mechanisms involved in tumor progression are understood. We have tested whether NF1 might be caused by the inactivation of a tumor suppressor gene on 17q, analogous to that on chromosome 22 in NF2, by searching for deletions of chromosome 17 in NF1-derived tumor specimens. Both neurofibrosarcomas from patients with "atypical" NF and 5 of 6 neurofibrosarcomas from NF1 patients displayed loss of alleles for polymorphic DNA markers on chromosome 17. However, the common region of deletion was on 17p and did not include the NF1 region of 17q. Since no loss of markers on chromosome 17 was observed in any of 30 benign tumors from NF1 patients, the 17p deletions seen in neurofibrosarcomas are probably associated with tumor progression and/or malignancy. This region contains a candidate gene for tumor progression, p53, which has recently been implicated in the progression of a broad array of human cancers. In a preliminary search for p53 aberrations by direct sequencing of polymerase chain reaction-amplified DNA from 7 neurofibrosarcomas, 2 tumors that contained point mutations in exon 4 of the p53 gene were found, suggesting a role for this gene in at least some neurofibrosarcomas. Thus the formation of malignant neurofibrosarcomas may result from several independent genetic events including mutation of the NF1 gene, whose mechanism of tumorigenesis remains uncertain, and subsequent loss of a "tumor suppressor" gene on 17p, most likely p53. PMID: 2142531 [PubMed - indexed for MEDLINE] ---------------------------------------------------------------