Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04637 (p53)
 77,613 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

When mammalian cells or tissues are exposed to DNA damaging agents a programmed cell death pathway is induced as well as a cell cycle arrest. In mice in which the p53 gene has been inactivated by homologous recombination this response is profoundly diminished. These mice develop normally so that developmentally induced apoptotic events do not require p53. The p53 gene product is a 393 amino acid nuclear protein that binds specifically to DNA and can act as a positive transcription factor. High levels of p53 can induce the transcription of gene products involved in the cell cycle arrest and apoptotic pathway. The p53 proteins activity is very tightly controlled both by allosteric regulation of its DNA binding function and by regulation of the protein's stability. These results are discussed in the context of the mutations in p53 found in human tumours and their implications for the treatment of the disease by the use of radiation and chemotherapeutic agents that target DNA.
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PMID:The role of the p53 protein in the apoptotic response. 784 26

p21WAF/CIP1/SDI1 is a recently identified gene expressed in cells harboring wild-type but not mutant p53 gene. It encodes a nuclear protein of 21 kD which inhibits cyclin-dependent kinase activity. Constitutive p21WAF1/CIP1/SDI1 mRNA expression was detected in neoplastic cells from patients with various hematological malignancies as well as in normal bone marrow mononuclear cells and in myeloid and lymphoid cell lines independent of their p53 status. Induced differentiation of the p53-deficient promyelocytic HL-60 cells along the monocytic lineage by phorbol ester or 1a,25 dihydroxyvitamin D3 resulted in a marked increase of both p21WAF1/CIP1/SDI1 mRNA and protein expression due to enhanced mRNA stability. Differentiation towards the granulocytic lineage by all-trans retinoic acid or dimethylsulfoxide failed to produce this effect. p21WAF1/CIP1/SDI1 is an immediate early gene since its upregulation occurred independently of de novo protein synthesis. The induction of p21WAF1/CIP1/SDI1 expression and its regulation in p53-deficient differentiating leukemic cells support the idea of an additional, p53-independent role of p21WAF1/CIP1/SDI1 in human hematopoiesis.
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PMID:Posttranscriptional stabilization underlies p53-independent induction of p21WAF1/CIP1/SDI1 in differentiating human leukemic cells. 788 98

The development of human adenocarcinoma of the lung involves multiple genetic changes including activation of oncogenes and loss of tumor suppressor genes. Patients whose lung tumors contain K-ras oncogene mutation, accumulation of the protein product of the tumor suppressor gene p53, or erbB-2/neu oncoprotein overexpression have been shown to have a worse prognosis. We examined these three genetic indicators in 29 lung adenocarcinomas to determine whether these markers are present in the same tumors or if they represent molecular changes that define different subsets of patients. P53 nuclear protein accumulation and erbB-2/neu protein overexpression were determined by immunohistochemical analysis of cryostat sections of tumor specimens and corresponding normal lung tissue. K-ras mutations were detected by radiolabeled oligonucleotide probes, specific for the various twelfth codon mutations, hybridized to exon 1 of K-ras, which was amplified by the polymerase chain reaction. Increased nuclear accumulation of p53 protein was found in 11 adenocarcinomas (38%). All of the p53 positive tumors were found to show high level staining and homogeneous expression of erbB-2/neu protein. K-ras mutations were detected in seven tumors (24%), all of which overexpressed erbB-2/neu. The presence of a K-ras mutation did not correlate with p53 accumulation. In total, 93% of the tumors were found to overexpress erbB-2/neu, the highest being in one tumor with erbB-2/neu gene amplification. The presence of K-ras twelfth codon mutation was associated with increased cigarette smoking. In conclusion, erbB-2/neu overexpression is a common event in lung adenocarcinomas. Furthermore, the presence of K-ras mutation and p53 protein accumulation define separate groups of patients. The mechanisms by which these genetic alterations interact or adversely affect prognosis is unknown.
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PMID:Alterations of K-ras, p53, and erbB-2/neu in human lung adenocarcinomas. 790 43

The expression of both the nuclear protein p53 tumor suppressor gene product and the transmembrane C-erbB-2 protein oncogene product (p185) correlates to risk factors and outcomes in different tumor types. Their value as prognosticators in endometrial adenocarcinoma of endometrioid type (EC) has not been determined. Paraffin sections were examined immunohistochemically to study the expression of p53 protein and p185 in 112 patients with EC. p53 protein was overaccumulated in 34% and p185 in 13% of the tumors. p53 protein correlated with mitotic count and nuclear grade. Both p53 protein and p185 correlated significantly with outcome. However, they did not correlate with each other or with architectural grade or stage (which defines a high risk group), indicating a role as adjuvant prognosticators in EC. Stage and outcome did correlate, however. Both p53 protein and p185 antibodies work well on routine, formalin-fixed, paraffin-embedded tissue and are easily used in routine diagnostic procedures.
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PMID:p53 protein and c-erbB-2 protein (p185) expression in endometrial adenocarcinoma of endometrioid type. An immunohistochemical examination on paraffin sections. 791 77

p53 is a tumor suppressor gene, located in the short arm of chromosome 17, which encodes for a nuclear protein involved in the control of cellular growth. Mutations in p53 gene are the most common genetic alterations in a several human cancers, including Non Small Cell Lung Cancer (NSCLC). However, up to now, the role of p53 in the tumour's behaviour and its progression has not been completely clear. We performed immunohistochemical staining for mutated p53 using two monoclonal antibodies, PAb1801 and PAb240, in fresh tumour specimens from 103 consecutive patients who underwent surgery for resectable NSCLC. PAb1801 detects both the normal and mutant form of p53, while PAb240 is specific only for the mutant form and recognizes a denaturation-resistant epitope located between aminoacids 156-335. Both antibodies showed a mainly nuclear staining in neoplastic cells but not in surrounding uninvolved lung tissues. 68 out of 100 (68%) and 37 out of 103 (35.9%) of the cases were positive with PAb1801 and with PAb240, respectively. Tumours from patients with hilar-mediastinal lymph node involvement showed a higher p53 expression, detected by PAb1801, than those without nodal metastases (p = 0.04). Moreover, tumours expressing more than 60% of positive cells with both antibodies showed a significant increase of nodal involvement (p = 0.1; p = 0.03). Furthermore, p53 expression was significantly related to post-surgical stage (p Tumor Stage) (p = 0.04). In addition, we did not find any correlation between p53 expression and proliferating activity evaluated by PCNA, Ki-67 and DNA flow cytometric cell cycle. In conclusion, the evaluation of p53 oncogene expression may identify individuals whose resectable NSCLCs have a more aggressive tumour behaviour.
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PMID:p53 expression in non small cell lung cancer: clinical and biological correlations. 810 Apr 13

Constant denaturant gel electrophoresis (CDGE) was used to screen 179 breast carcinomas for mutations in the conserved regions of the TP53 gene (exons 5 through 8). Mutations were found in 35 of 163 primary tumours (21%) and in 5 of 16 metastases (31%) and resided predominantly in exon 7. The majority of the mutations were G:C-->A:T transitions. Immunohistochemistry demonstrated nuclear accumulation of p53 protein in 35 of 162 primary tumours (22%) and in four of 15 metastases (27%). TP53 mutation was strongly associated with nuclear accumulation of p53 protein. In total 42 of 163 primary tumours (26%) and 5 of 16 metastases (31%) were demonstrated to contain TP53 alterations (mutation and/or nuclear protein accumulation). TP53 alteration in primary tumour was significantly associated with the following parameters: positive node status, T status > 1, negative oestrogen receptor status, negative progesterone receptor status, presence of ERBB2 gene amplification, and invasive ductal histology. Furthermore, there were statistically significant associations, independent of other prognostic factors, between TP53 alterations in primary tumour and disease-free and overall survival.
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PMID:Prognostic significance of TP53 alterations in breast carcinoma. 810 35

The aim of this study was to evaluate the power of quantitative pathology in improving the accuracy of prognosis in ductal infiltrating breast carcinoma. Ninety tumours were studied, with a diameter < or = 2.5 cm; positive (metastatic) axillary lymph nodes were found in 48 of the 90 cases; no patient had systemic metastases. Surviving patients had a mean follow-up of 106 months (minimum 69 months). At the end of the study, 45 patients were alive, 45 deceased. The histopathologic study of tumour nuclei and nucleoli included: a) geometric features, i.e., the mean and standard deviation of nuclear area, perimeter, diameter and form factor, nucleolar area and nucleolar/nuclear ratio, measured with a Kontron-IBAS automatic image analyser; b) immunohistochemical features, i.e., the percentage of PCNA (Proliferating Cell Nuclear Antigen)-positive nuclei, the expression (positive or negative) of vimentin (as a marker of tumour dedifferentiation), and the nuclear protein p53. Statistically significant differences were found between surviving and decreased patients for most features; multivariate analysis gave 92.2% accuracy in predicting outcome. Among the classes defined with multivariate analysis, it was possible to distinguish subsets of patients with bad prognosis by studying the expression of vimentin and p53, although these markers were positive in a small number of cases: 5 out of 6 patients with vimentin positivity and 4 out of 8 with p53 positivity died within 24 months of the diagnosis.
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PMID:Multivariate quantitative histopathological assessment of prognostic factors in ductal infiltrating breast carcinoma. 810 96

The expression of the nuclear protein p53 in oligodendrogliomas was investigated by immunohistochemistry, using a monoclonal anti-p53 antibody (DO-7) on formalin-fixed, paraffin-embedded material in 84 histologically verified cases, and compared with the histopathological grade and survival. p53-immunoreactive cells were found in 75 per cent of the samples acquired at the first biopsy. The p53 labelling index was not related to the degree of nuclear anaplasia. Tumour cases with more than 75 per cent p53 immunostained cells had a rapidly fatal clinical course. However, no significant correlation was found between p53 labelling index and tumour grade, mitotic index, or ploidy status. In most tumour recurrences (n = 25), the p53 labelling index increased or remained at the level of the first biopsy. In five cases (6 per cent), p53 was absent in the first sample as well as in the recurrence. Irrespective of the underlying aberration of either the gene or the metabolic pathway of p53, it is concluded that a high percentage (i.e., more than 75 per cent) of p53-immunolabelled cells is predictive of an unfavourable clinical course, while a percentage lower than 75 per cent immunoreactive cells does not exclude a rapid fatal outcome.
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PMID:Expression of p53 in oligodendrogliomas. 815 58

The wild-type tumor-suppressor TP53 gene encodes for a nuclear protein which has been shown to act as a transcriptional modulator. The cellular role of the p53 protein is the control of cell proliferation, particularly important in stressed cells. The TP53 gene is frequently mutated in sporadic and familial human cancers. Most transforming mutations localize in highly conserved domains of the gene and define hot-spot regions that have a certain degree of tissue specificity. Moreover, most mutations are point mutations and the type and localization of the nucleotide substitution may sometimes help in recognizing the carcinogenic agent. This is the case for C to T transitions at dipyrimidine sites induced by UV radiation in cutaneous epitheliomas. Inactivation of p53 protein can also occur through mechanisms other than genetic alteration, such as binding to viral or cellular proteins. Loss of wild-type TP53 function seems therefore to play a crucial role in cell transformation in human cancers, either during carcinogenesis or later in tumor progression.
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PMID:TP53 tumor-suppressor gene and human carcinogenesis. 816 31

The purpose of this study was to analyze the expression of a mutant (MUT) p53 oncogene protein in the mucosal crypts adjacent to a human colon cancer. Five 1-cm mucosal segments were taken from the surgical specimens over a 5-cm distance from the tumor. Immunohistochemistry was performed using a monoclonal antibody (Ab3) to the MUT p53 and examination by light microscopy. The mean % labelling index (LI) of 10 crypts/cm segment was determined by image analysis. The LI for the entire crypt length for the first cm segment was 33.51 +/- 4.2 and for the second cm segment was 29.26 +/- 5.4 (p < 0.02). Due to the unequal distribution of the label within the crypt length, it was divided into halves so that the LI of these levels could be determined. The LI for the upper and lower crypt levels for the first cm segment were 28.67 +/- 3.2 and 78.23 +/- 4.6 (p < 0.01); for the second segment, the LI were 22.0 +/- 5.1 and 68.66 +/- 4.7 (p < 0.01). No expression of MUT p53 nuclear protein was noted distally at 3-5 cm. The localization of MUT p53 protein product to the crypt stem cell nucleus supports the contention that a malignant field change exists in the transitional mucosa adjacent to a human colon cancer.
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PMID:Immunohistochemical expression of mutant p53 oncogene in transitional mucosa adjacent to human colon cancer. 826 91


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