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

Molecular abnormalities of the p53 gene in chromosome 17p may be among the most commonly observed in human cancer. Their role in gastric carcinogenesis is suggested by their frequent detection in invasive adenocarcinomas. To investigate the chronology with which these abnormalities appear in the gastric carcinogenesis process, the expression of p53 proteins was investigated in late stages of the process, namely dysplasia, and in superficial carcinomas. A polyclonal antibody, CM-1, against both wild-type and mutant proteins was applied to paraffin-embedded biopsy and gastrectomy specimens previously fixed in buffered formalin. Positive nuclear stain was obtained in 36.4% of 33 cases of gastric epithelial dysplasia, corresponding to 19% of mild, 27.3% of moderate, and 64.3% of severe dysplasias. Eight of 13 (61.5%) invasive carcinomas showed positive stain. The data indicate an increased incidence of p53 abnormalities in the late stages of gastric carcinogenesis.
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PMID:Immunohistochemical evidence of p53 overexpression in gastric epithelial dysplasia. 130 67

The expression of p53 gene has been found to be regulated during the induction of differentiation of U937 leukemic cells into mature macrophages by recombinant human granulocyte- macrophage colony stimulating factors (rhGM-CSF) We showed here that the increased expression of p53 seemed to be necessary for the differentiation of U937 cells induced by rh-GM-CSF. The inhibition of p53 expression by a p53 antisense oligodeoxynucleotide lead to the significant decrease of formation of mature macrophages from U 937 cells in the presence of rhGM-CSF. By contrast, the p53 sense oligodeoxynucleotide had no any effect. Furthermore, we have analysed the growth of U937 cells in the presence or absence of rhGM-CSF. The results showed that rhGM-CSF dramatically inhibited the growth of U 937 cells in the cultures. At the same time, the antisense inhibition experiment demonstrated that the inhibition of p53 expression partially diminished the growth-inhibitory effect of rhGM-CSF on U 937 cells. These results suggested that the p53 was required for the initiation of rhGM-CSF-induced differentiation of U 937 cells on one hand, and the inhibition of cell growth on the other hand. Thus we deduce that the increased expression of p53 induced by rhGM-CSF may be a coupling event of switch of U 937 cells from growth into differentiation.
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PMID:[The role of p53 gene in the switch of U937 leukemic cells from growth into differentiation]. 130 2

Multiple genome alterations can be seen within a tumor and continue to accumulate throughout development of the growth. Chromosome deletions occurring in tumors are generating much interest. To date, the best known model is retinoblastoma whose study gave rise to the concepts of anti-oncogene or tumor suppressor gene. Studies of genetic anomalies in colorectal tumors have led to an elegant model of colonic carcinogenesis in which multiple steps, each with its corresponding genetic anomaly, successively accumulate, with deletion of the p53 gene occurring as a late event. Successive anomalies of the p53 gene (mutations, deletions) occur during passage from a low-grade astrocytoma to a higher-grade astrocytoma. Studies of familial forms of breast cancer and of breast and ovarian cancer have also provided insight into the biology of these tumors, with the identification of a predisposing chromosomal area whose location is 17 q-12-21. These approaches open up possibilities for screening techniques and use of preventive treatments in highly selected patients. However they raise many ethical problems. There is a need for developing a charter for these family studies in the near future.
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PMID:[Genetics and cancers]. 130 91

The etiology of cancer is a complex interplay of various factors, including genetic alterations. Multiple studies have been carried out to identify and characterize mutations that frequently occur during tumorigenesis. In human breast cancer, amplification of proto-oncogenes (c-myc, c-erbB-2/neu) and chromosome 11q13, mutation of p53 and loss of heterozygosity (chromosomes 1, 3p, 6q, 7q, 11p, 13q, 16q, 17, 18q and 22q) represent the major types of genetic abnormalities that have been frequently observed in tumor DNAs. The genetic deletions and mutations could inactivate tumor-suppressor genes. In some studies, specific alterations have been associated with some clinical parameters. Recently, linkage analyses, on large families with a predisposition to breast cancer, have been performed to map putative breast cancer susceptibility genes. The survey of high risk patients should be organised to make an earlier diagnosis.
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PMID:[Molecular analysis of breast cancers: recent developments]. 130 32

There are few cytogenetic studies of early (non-invasive) bladder cancer, particularly in situ carcinoma, due to technical difficulties in examining such lesions. The best approach is to extrapolate from chromosomal changes in more advanced cancers. Although no specific chromosomal changes have been established in either early or fully developed bladder cancers, certain recurrent anomalies have been encountered. Anomalies such as +1, +7, -9, 5q- or i(5p), 11p- and -Y appear to constitute part of the multistep carcinogenetic process by which clinically and pathologically recognizable bladder cancers develop. Since loss of part or all of chromosome 9 (-9) is a common and early cytogenetic event in bladder cancer, the detection of -9 in bladder washings or urine by fluorescence in situ hybridization (FISH) may be a promising test for early or recurrent bladder cancer. Although less frequent than -9, trisomy 7 (+7) is common enough to serve a similar purpose. In contrast, loss of the Y chromosome may indicate an advanced stage of bladder cancer. Thus, FISH studies utilizing probes for chromosomes 7, 9, and Y should yield cogent information to identify early bladder cancer. Cytogenetic (including FISH) studies combined with certain molecular approaches (e.g., p53 mutations detected immunochemically) may not only serve to differentiate early cancer from benign tumors or conditions, but may also help establish cancer stage. This would supply data of considerable usefulness to the clinician and pathologist.
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PMID:Chromosome changes in early bladder neoplasms. 130 93

Using monoclonal antibodies, we have identified a series of tumor-associated antigens selectively expressed on tumor subtypes with distinct clinical behaviours. The mucinous antigen M344 and the gp200 surface antigen 19A211 are preferentially expressed on papillary superficial tumors and carcinoma in situ lesions of the bladder. The combination of these two antigenic markers in immunocytology and flow cytometry studies of exfoliated cells has improved the sensitivity of detection for bladder tumors. Moreover, the detection of M344- and 19A211-positive exfoliated cells from previously treated but currently tumor-free patients appears to be predictive of tumor recurrence on follow-up. These results, as well as results of bladder mapping studies in tumor patients, suggest that these antigenic changes occur in a premalignant stage and may provide tools to monitor the efficacy of chemopreventive measures. Other markers, such as the surface antigen T138 and the soluble molecules autocrine motility factor (AMF) and tumor collagenase stimulating factor (TCSF), are produced by primary or recurrent tumors with a higher metastatic potential. They may be useful in identifying high risk patients for distant failure. The highly restricted antigen 19A211 is also expressed on cervix condylomas and carcinoma. This observation led us to investigate a possible viral etiology of some bladder cancers. Using PCR techniques, we detected the presence of human papillomavirus (HPV) 16 DNA sequences in a significant proportion of bladder tumors. HPV positivity was inversely correlated with the presence of p53 mutations in exons 5-9 of the same tumors as measured by PCR-SSCP technique. This combination of markers may provide a basis for chemoprevention strategies targeted to distinct etiological events.
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PMID:Strategies of chemoprevention based on antigenic and molecular markers of early and premalignant lesions of the bladder. 130 95

Out of a total of 1,600 foreign students who came to India between June 1989 and October 1990, 22 were seropositive for HIV-1. Ten showed antibodies to all the gene products. Antibodies to gp160 and p24 were present in all the seropositives while antibodies to p53, p15/17 were significantly higher in healthy seropositives than in patients with full blown AIDS. Absence of antibodies to p15/17 and p53 thus appeared to be a more sensitive criterion of end stage disease than absence of anti- p24 antibodies. When seropositive samples from African students were checked for HIV-2 antibodies by ELISA, 13/22 were found to be positive. Further, 2/10 Indians with full blown AIDS were also strongly positive for HIV-2. These data could be of relevance for formulating future strategies for population-based screening for HIV-2.
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PMID:Comparative evaluation of HIV infected foreign students and Indian with AIDS in Chandigarh, India. 130 16

We have examined breast tumour samples from 109 unselected breast cancer patients for genetic changes on chromosomes 13 and 17. We have looked for allelic losses, firstly, at the retinoblastoma locus, RB1, on chromosome 13q, and secondly, on both arms of chromosome 17. We have also studied the same samples for amplification of the erbB2 oncogene. We searched for mutations in four well conserved areas of the p53 gene using constant denaturant gradient electrophoresis (CDGE). Allelic loss or rearrangement was detected in a large proportion of the tumours, affecting 37-51% of cases with different probes. The areas most frequently affected were 17p13.1 and 17p13.3. Point mutations and small deletions in the p53 gene on 17p13.1 were detected in 16% of the tumours. The data on genetic changes were then analyzed for three different correlations: 1) co-operation between different lesions, 2) association with family history of breast cancer, 3) correlation with clinical factors and prognosis. There was association between losses at the retinoblastoma locus and losses on 17p and 17q. We also found an association between p53 mutations and amplification of the erbB2 oncogene. Relatives of patients having deletions at the retinoblastoma locus and/or sites on chromosome 17 in the tumours have a significantly increased relative risk of developing breast cancer. No such correlation is found for p53 mutations or erbB2 amplification. No p53 germline mutations were detected. P53 mutations do, however, appear to be a strong indication of poor prognosis in this population.
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PMID:Genetic changes in breast carcinomas in an Icelandic population. 130 32

Evolutionary aspects of human cancer can be dealt with at two levels--on the one hand long-term evolution involving hereditary effects between generations; and on the other hand evolutionary processes operating within the organisms between tissues, cells and cell constituents, which also comprise genetic alterations, selection and adaptation. These two levels of evolution can be designated as phylogenetic and ontogenetic evolution, respectively. Concerning phylogenetic evolution there must have been a strong selection against neoplastic diseases occurring at reproductive age and a variety of protective mechanisms against carcinogenic agents have been developed. Cancer is therefore primarily a disease of old age, which does not constitute a significant risk in natural populations for the simple reason that the life length is too short. The development of an individual comprises selection forces between cells and tissues, which are particularly striking for the multistage development of tumours. The accumulation of several genetic alterations in the same cells, as illustrated by the analysis of colorectal tumours, must require a pronounced clonal expansion between each event. Such selective growth effect has recently been demonstrated for the tumour suppressor gene p53 in brain tumours. Cancer often implies a break down of between balanced systems antagonistic forces, such as oncogenes and suppressors of oncogenes. Examples of this are provided by the genetic regulation of metastasis, involving metalloproteinase as well as the inhibitor of metalloproteinase. The immortalization of cells by transformation points to the fact that programmed cell death and the balance between suicide genes and suppressors of such suicide genes is affected.
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PMID:Evolutionary aspects of human cancer. 130 36

The authors investigated methods for analysis of oncogenes and tumor suppressor genes in lung cancers and bronchial lesions from high risk patients (retired poison gas factory workers). Amplifications of C-, L-, N-myc, length of terminal repeat array (TRA), mutations of p53 gene, p53 mRNA and K-ras genes were analysed in frozen specimens of surgically resected lung cancers. Various lesions including dysplasia, squamous metaplasia, goblet cell metaplasia, and basal cell hyperplasia were detected in the bronchial epithelium of biopsied specimens from retired poison gas factory workers. Analysis of p53 gene and k-ras gene mutations was performed on these formalin fixed, paraffin embedded samples, but no evidence of mutation has been found to date.
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PMID:[Analysis of oncogenes and suppressor genes in lung cancer and bronchial lesions from high risk group]. 130 37


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