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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have examined whether alterations of simple (CA)n DNA repeats, as observed in human colon cancers, occur during human gastric carcinogenesis and whether such alterations reflect genomic instability that could lead to other genetic changes. A total of 22 gastric cancer samples were analyzed: 15 well or moderately differentiated adenocarcinomas, 6 signet-ring cell carcinomas, and 1 poorly differentiated adenocarcinoma. When (CA)n repeat sequences were examined at 10 loci, one adenocarcinoma showed a loss of repeat sequences at five loci, three adenocarcinomas gained a repeat at one locus, and one adenocarcinoma had new, repeated sequences at five loci. Three samples showed mutations in the p53 gene, two in exon 5 (both GC to AT transition at a CpG dinucleotide) and one in exon 7 (AT to GC transition). Only one sample with a p53 mutation also showed altered (CA)n repeats. A putative tumor suppressor gene, connexin 32, was not altered as assessed by single-strand conformation polymorphism analysis. These results suggest that genomic instability revealed by (CA)n repeat changes does not seem to contribute to induction of point mutations in p53 or connexin 32 genes but may participate in loss of heterozygosity at APC/MCC loci. The results are consistent with the hypothesis that different mechanisms are involved in the gain and loss of (CA)n repeats.
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PMID:Alterations of (CA)n DNA repeats and tumor suppressor genes in human gastric cancer. 826 59

The tumors of 20 patients with multifocal primary transitional cell carcinoma of the bladder or lymph node metastases were examined for molecular genetic defects which we have previously found to be present in > 50% of invasive tumors. These included loss of heterozygosity (LOH) of chromosome 9, which occurs in superficial as well as invasive bladder tumors, and LOH of chromosome 17p and p53 mutations, which are commonly found only in invasive tumors. Analysis of multiple or recurrent primary tumors in 7 patients for these markers was generally consistent with recently published data that the tumors are monoclonal in origin and that p53 mutations occur as a late event in the generation of invasive bladder cancers. Comparison of the primary tumors and metastases to regional lymph nodes in 14 patients demonstrated a complete concordance between the molecular genetic defects present, showing that LOH of chromosomes 9 and 17p and p53 mutations occurred in the primary tumors before metastasis. Because of the importance of chromosome 9 in bladder cancer, we mapped the location of a putative tumor suppressor gene by restriction fragment length polymorphism analysis of 123 cases obtained in this and earlier studies. Most of the tumors showed LOH for more than one marker on chromosome 9. Results of mapping of 4 tumors with partial deletion of chromosome 9 suggests that the tumor suppressor gene is located between 9p12 and 9q34.1.
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PMID:Role of chromosome 9 in human bladder cancer. 835 36

Cancer is associated with homozygous deletions of specific DNA sequences that are in some instances too small to be detectable by cytogenetic methods or Southern blot analysis. Such small tumor-specific deletions can be detected, however, by the polymerase chain reaction (PCR) provided that tumor cells are meticulously and verifiably isolated from contaminating nontumor cells. Nontumor cells can give positive PCR results and thus obscure the detection of deletions. Using a method that allows accurate and verifiable excision of tumor cells for subsequent PCR analysis, homozygous deletions, one in a putative tumor suppressor gene on chromosome 8 and one in the p53 gene, were detected in two out of 20 human lung carcinomas investigated.
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PMID:Detection of tumor-specific homozygous deletions in human biopsies by polymerase chain reaction. 845 8

The past few years have seen remarkable progress in understanding the molecular genetic basis of glioma formation. Affected oncogenes and tumor suppressor genes have been identified and putative tumor suppressor loci have been mapped. These studies have illustrated distinct molecular pathways for different glial neoplasms. We summarize the findings of an ongoing study initiated to characterize human gliomas on a molecular basis. The data are compiled from 150 astrocytic, oligodendroglial, and mixed gliomas that were assessed for genomic alterations characteristic of these neoplasms, i.e., loss of portions of chromosomes 1p, 9p, 10, 17p, 17q, and 19q, mutations of the p53 tumor suppressor gene, and amplification of the EGF receptor (EGFR) gene. Our findings support the hypothesis that distinct genetic pathways result in the formation of astrocytic and oligodendroglial neoplasms of different malignancy grades, and that glioblastoma multiforme may be subdivided into genetically distinct subsets. Such findings may not only lead to a better understanding of neoplastic transformation in glial cells, but may also have a major impact on clinical neuro-oncology.
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PMID:Molecular pathways in the formation of gliomas. 858 67

Although the initial chemo-radiotherapy is relatively effective, lung cancer, especially small cell lung cancer (SCLC) usually becomes resistant for the therapy and gets higher grade of the malignant phenotype. The common genetic abnormalities, such as 3p deletion and mutational inactivation of p53 and Rb gene, have been well known. However, these abnormalities seem to be involved in the development of lung cancer because they could be detected at the early stage or even in the preneoplastic lesion. By means of loss of heterozygosity (LOH), we have determined two regions which are frequently lost in advanced lung cancer, 5q21 and 5q33-35. In previous reports, the low frequency of 5q loss in lung cancer has been shown in masses obtained at early but not advanced stages. Furthermore, we have found that one SCLC case showed a 5q deletion only in metastatic site but not in the primary lesion. These findings suggest that the inactivation of putative tumor suppressor gene(s) on 5q may play an important role for the progression of lung cancer. In 5q21 area, commonly deleted region was estimated to be 3 Mb around APC gene. This region was covered with several YAC clones and some cosmid contigs were constructed from these YAC clones. Two kinds of transcriptional units have been isolated from these contigs by exon-trapping, cross-species hybridization or northern blotting, so far. Since these cDNAs do not show significant homology with any known gene, their function cannot be estimated. We are trying to isolate full length cDNAs and to determine the functional and structural abnormalities in lung cancer at present.
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PMID:[Search for the tumor-suppressor gene(s) on chromosome 5q, which may play an important role for the progression of lung cancer]. 883 1

Using the methods of restriction fragment length polymorphism (RFLP) and single strand conformation polymorphism (SSCP) analyses, we have examined 33 cases of human gliomas with various malignant grades to detect the deletions of putative tumor suppressor gene loci, chromosome 10, 13q(retinoblastoma gene, Rb), 17p, and p53 mutation. We observed loss of heterozygosity (LOH) at loci on chromosome 10 (36%), 13q(Rb) (54%), and 17p(50%) in malignant gliomas. There, however was no allelic loss on chromosome 10 and 17p in low-grade gliomas. Rb gene deletions were seen in low-grade gliomas, including oligodendroglioma and ependymoma. This finding suggests that Rb inactivation may be an early genetic event in the development and progression of gliomas. We correlated the results of LOH on chromosome 17p and p53 mutation. Among the 8 cases which showed LOH on chromosome 17p, only three cases (38%) revealed p53 mutations. Low incidence of p53 mutations in cases with chromosome 17p deletions suggests that some other tumor suppressor genes may be located on chromosome 17p.
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PMID:Loss of heterozygosity on chromosome 10, 13q(Rb), 17p, and p53 gene mutations in human brain gliomas. 892 30

Bladder cancer is the result of a clonal expansion of cancer cells in which multiple genetic alterations have accumulated. Point mutations of the p53 gene are frequently observed in bladder cancer. Loss of a retinoblastoma (Rb) allele is also common in bladder cancer. Recent data have shown frequent loss of heterozygosity (LOH) and homozygous deletion of 9p21, including the region of p16INK4A, a putative tumor suppressor gene, in bladder cancer. LOH is also observed frequently at several other chromosome regions in bladder cancer. These genetic changes have proved useful as clonal markers in the detection of cancer cells in urine. Because of their complexity, most molecular diagnostic approaches are not considered promising cancer screening tools in patients or high-risk populations. However, a new molecular approach, the examination of microsatellite alterations in bladder cancer and urine specimens, is a promising screening tool for the disease. The common genetic alterations in bladder cancer and their use as clonal markers in screening or diagnosis strategies will be discussed.
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PMID:Genetic alterations as clonal markers for bladder cancer detection in urine. 902 18

Alterations, especially homozygous deletions, of the putative tumor suppressor gene, p16 (p16INK4A, MTS1, CDKN2) have been found in tumor cell lines from a variety of neoplasms. Recent studies have reported frequent p16 gene deletions in cell lines from squamous cell carcinomas of the head and neck (SCCHN), although the prevalence of alterations was variable in primary tumors. This study determined the prevalence of point mutations and deletions of the p16 gene in 33 SCCHN. In addition, the association of p16 gene alterations and abnormalities of p53, PRAD-1 (cyclin D1), and the presence of human papillomavirus (HPV) was examined. We found an overall prevalence of p16 alterations of 36% (nine deletions, three single base substitutions, including one polymorphism). Seven tumors (of 29, 24%) had an alteration of p16 and p53; five (of 33, 15%) had alterations of p16 and PRAD-1; three (of 29, 10%) had alterations of all three genes. In addition, of the five tumors with human papillomavirus detected, only one also had a p16 gene alteration. The results indicate a potentially important role for the p16 gene in head and neck tumorigenesis. In addition, the presence of tumors with multiple somatic gene alterations suggest a possible interaction in the dysregulation of the cell cycle.
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PMID:Alterations of the p16 gene in head and neck cancer: frequency and association with p53, PRAD-1 and HPV. 904 88

Recently, a human homologue of the Drosophila patched gene, PTCH, was identified as a putative tumor suppressor mutated in both hereditary and sporadic basal cell carcinomas. Because PTCH controls its own transcription, inactivating mutations in PTCH may lead to overexpression of mutant PTCH mRNA due to loss of autoregulation. The present study is aimed at evaluating whether deregulation of PTCH mRNA expression is a general feature of BCCs of varying histological growth pattern and malignant potential. Irrespective of histological subtype, PTCH mRNA was overexpressed consistently as determined by in situ hybridization in all of the sporadic (n = 16) and hereditary (n = 20) tumors examined. PTCH expression was found in all of the tumor cells but appeared stronger in the peripheral palisading cells. PTCH mRNA was not detected in adjacent nontumor epidermal cells or in other parts of the epidermis. In the majority of tumors (20 of 36), nuclear immunostaining for p53 was found in scattered cells, whereas seven tumors completely lacked p53 immunoreactivity. Our finding of an up-regulation of PTCH mRNA levels in all of the BCCs analyzed indicates that deregulation of the PTCH signaling pathway constitutes an early rate-limiting event in BCC development.
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PMID:Human patched (PTCH) mRNA is overexpressed consistently in tumor cells of both familial and sporadic basal cell carcinoma. 919 3

Lung cancer is the most common cause of cancer death in Japanese males, the incidence having increased markedly in recent years. Carcinogen exposure such as to tobacco-smoke and air pollution are associated with the probability of developing lung cancer. Aquired somatic mutations play an important role in the pathogenesis of environmentally induced lung cancers. Cytogenetic and molecular analysis of lung tumors has made it possible to examine this hypothesis and to search for candidate genes that may be targeted by chronic exposure to these carcinogens. Early studies implicate several distinct chromosomal loci (3p, 9p, 13q, 17p, and others) and suggest sequential genetic events occur during the initiation and progression of lung carcinogenesis. Several suppressor genes including Rb (13q), P53 (17p), and P16 (9p) have been identified and cloned at these chromosomal loci. The identification of putative tumor suppressor gene at chromosome 3p is still under work. Understanding the interaction of P53, RB, cyclins, and protein kinase inhibitors including P16 will be essential to the development of the next generation of diagnostic and therapeutic studies for lung cancer.
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PMID:Tumor suppressor genes in human lung cancer. 939 13


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