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)

p21 (CDKN1A/CIP1/WAF1), one of the cyclin-dependent kinase inhibitors, plays a key role in regulating the cell cycle and is transcriptionally regulated by p53. Down-regulation of p21 is caused by TP53 mutations in colorectal cancer. CpG island methylator phenotype (CIMP) appears to be a distinct subtype of colorectal cancer with concordant methylation of multiple gene promoters and is associated with a high degree of microsatellite instability (MSI-H) and BRAF mutations. However, no study to date has evaluated the relationship between p21 expression and CIMP in colorectal cancer. The purpose of this study was to examine the inter-relationships between p21, p53, CIMP, MSI and KRAS/BRAF status in colorectal cancer. We utilized 737 relatively unbiased samples of colorectal cancers from two large prospective cohort studies. Using quantitative real-time PCR (MethyLight), we measured DNA methylation in five CIMP-specific gene promoters [CACNA1G, CDKN2A (p16/INK4A), CRABP1, MLH1 and NEUROG1]. CIMP-high (>or=4/5 methylated promoters) was diagnosed in 118 (16%) of the 737 tumours. We also assessed expression of p21 and p53 by immunohistochemistry. Among the 737 tumours, 371 (50%) showed p21 loss. Both p21 loss and p53 positivity were inversely associated with CIMP-high, MSI-H and BRAF mutations. The associations of p21 with these molecular features were still present after tumours were stratified by p53 status. In contrast, the associations of p53 positivity with the molecular features were no longer present after tumours were stratified by p21 status. When CIMP-high and non-CIMP-high tumours were stratified by MSI or KRAS/BRAF status, CIMP-high and MSI-H (but not BRAF mutations) were still inversely associated with p21 loss. In conclusion, down-regulation of p21 is inversely correlated with CIMP-high and MSI-H in colorectal cancer, independent of TP53 and BRAF status.
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PMID:Down-regulation of p21 (CDKN1A/CIP1) is inversely associated with microsatellite instability and CpG island methylator phenotype (CIMP) in colorectal cancer. 1685 May 2

Patients with stage I colorectal cancer have a good prognosis, however, a small fraction of them die of local or distant recurrence after curative resection. The aggressive behavior reflects some biological properties of these tumors. In this study, we evaluated the prognostic role of some histopathological and biological parameters in stage I colorectal carcinomas. From the Colorectal Cancer Registry of Modena, we selected two series of patients; the first included all patients who had died of disease progression, the second included patients with a favorable outcome. The histopathological parameters assessed were grade of differentiation, growth pattern at the invasive tumor front, peritumoral lymphocytic infiltration, tumor budding and vascular invasion. The biological variables were proliferative activity (using Ki-67 nuclear antigen), overexpression of p53 protein and altered expression of the mismatch repair proteins (MLH1 and MSH2). The results showed that an infiltrating growth pattern, absent or sparse peritumoral lymphocytic infiltration, the presence of tumor budding and vascular invasion are significantly related to the risk of recurrence. Among the biological parameters, p53 overexpression was significantly correlated with a poor clinical outcome. Our study showed that the histopathologial features are relevant prognostic indicators and might be used as markers for an appropriate treatment strategy in patients with stage I carcinomas.
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PMID:Prognostic significance of histological features and biological parameters in stage I (pT1 and pT2) colorectal adenocarcinoma. 1686 Apr 93

Microsatellite instability (MSI) has been associated with colitic cancer. However, reported frequency of MSI was varied and the association of MSI with mismatch repair (MMR) deficiency was unclear. In addition, the occurrence of genetic alterations in stromal cells within ulcerative colitis (UC) is still controversial. We therefore sampled 164 microareas in various pathological lesions of UC with or without colitic cancer and studied the MSI status in relation to the DNA repair protein expressions. A total of 129 microfoci from colorectal tissue of 5 colitic cancer patients and 35 microfoci of 7 UC patients (without neoplasm) were carefully sampled by laser-capture microdissection. MSI was analyzed in each microsamples. The protein expression of MMR genes (MLH1, MSH2, MSH6), O(6)-methylguanine-DNA methyltransferase and p53 were assessed by immunohistochemical analysis. Variety of di-nulcleotide microsatellite markers was altered in individual microfoci from different morphological epithelial lesions, in full range of nonneoplastic epithelium to colitic cancer. Interestingly, MSI was not observed in stromal cells at any sites, including those within colitic cancer/dysplasia lesions. Expression of the MMR proteins was not lost in any of the lesions examined. Microsatellite alterations rather seem to be related to the initiation than to the progression of colitic cancer.
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PMID:Heterogeneous microsatellite instability observed within epithelium of ulcerative colitis. 1692 96

Alternative splicing produces more than one protein from the majority of genes and the rarer forms can have dominant functions. Instability of alternative transcripts can also hinder the study of regulation of gene expression by alternative splicing. To investigate the true extent of alternative splicing we have developed a simple method of enriching alternatively spliced isoforms (EASI) from PCRs using beads charged with Thermus aquaticus single-stranded DNA-binding protein (T.Aq ssb). This directly purifies the single-stranded regions of heteroduplexes between alternative splices formed in the PCR, enabling direct sequencing of all the rare alternative splice forms of any gene. As a proof of principle the alternative transcripts of three tumour suppressor genes, TP53, MLH1 and MSH2, were isolated from testis cDNA. These contain missing exons, cryptic splice sites or include completely novel exons. EASI beads are stable for months in the fridge and can be easily combined with standard protocols to speed the cloning of novel transcripts.
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PMID:EASI--enrichment of alternatively spliced isoforms. 1695 Dec 90

Colorectal carcinoma is a frequent malignant tumor, characterized by varying clinical course and response to treatment. At the molecular level, colorectal carcinomas are divided into tumors with chromosomal instability (microsatellite-stable, MSS), microsatellite instability (MSI-H) and low microsatellite instability (MSI-L). The method of tissue microarrays allows for combining materials originating from multiple patients into a single slide, what makes possible to simultaneously investigate large material for the presence of numerous, diversified markers. The study material consisted of 208 cases of colorectal carcinoma. Microsatellite instability was evaluated in frozen material employing the PCR reaction with gel and capillary electrophoresis. Following a standard histopathological assessment, tissue microarrays were prepared using a MTA-1 microarrayer (Beecher) and standard immunohistochemical reactions were performed to detect the presence of bcl-2, CDX-2, Ki67, MLH1, MSH2, MSH6, p16, p53 and survivin. Apoptotic cells were detected using the TUNEL method. The correlations between the reactions were investigated and differences in the expression of the investigated proteins noted in carcinomas with various degrees of microsatellite instability. The agglomeration analysis showed differences in patterns of expression between MSS, MSI-L and MSI-H carcinomas. The discriminant function analysis demonstrated that the MSI-H carcinomas were best differentiated by MLH1, survivin and Ki67 expression, while the MSI-L tumors differed from the remaining colorectal carcinomas by their apoptotic index, local tumor stage (pT), the presence of angioinvasion and mucin production.
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PMID:Correlation of microsatellite status, proliferation, apoptotic and selected immunohistochemical markers in colorectal carcinoma studied with tissue microarray. 1701 73

It has been hypothesized that defects in DNA-mismatch repair are associated with smoking in certain types of transformed non-Hodgkin lymphoma (NHL). We have analyzed biopsy samples from two indolent B-cell lymphomas, follicular lymphoma (FL) and chronic lymphocytic leukemia/small lymphocytic leukemia (CLL/SLL), that have transformed to diffuse-large B-cell lymphoma (DLBCL). We correlated the presence or absence of DNA-mismatch repair enzymes by immunostaining as well as the p53 status to smoking history. Of all patients (n = 30), 37% showed negative immunostaining of MLH1, 16% showed negative immunostaining of MSH2 and 63% had p53 mutations and/or protein expression. Eighteen out of 20 transformed follicular lymphomas and seven out of 10 CLL/SLL that have transformed to DLBCL (Richter's syndrome) were informative for smoking histories. We found that the relative risk of negative immunostaining for either MLH1 or MSH2 was 2.2 times higher in smokers than non-smokers (relative risk = 2.2041, 95% confidence interval: 0.89714, 5.41491). No direct correlation was found between smoking and the mutations in the p53 gene. These results suggest that cigarette smoking may play a role in the development of transformed lymphomas through defective mismatch repair.
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PMID:Expression of DNA mismatch repair proteins in transformed non-Hodgkin's lymphoma: relationship to smoking. 1706 78

Downregulation of p27 (cyclin-dependent kinase inhibitor-1B, CDKN1B or KIP1) is caused by increased ubiquitin-mediated proteasomal degradation in colorectal cancer, and has been associated with poor prognosis. CpG island methylator phenotype (CIMP) is a phenotype of colorectal cancer with extensive promoter methylation, and associated with high degree of microsatellite instability (MSI-H) and BRAF mutations. We have recently shown that both CIMP and MSI-H are inversely associated with downregulation of p21 (CDKN1A or CIP1), another cyclin-dependent kinase inhibitor. However, no study to date has examined relationship between p27 and CIMP status in colorectal cancer. Using MethyLight assays, we measured DNA methylation in five CIMP-specific gene promoters {CACNA1G, CDKN2A (p16), CRABP1, MLH1 and NEUROG1} in 706 colorectal cancer samples obtained from two large prospective cohorts. Among the 706 tumors, 112 (16%) were CIMP-high tumors with >or=4/5 methylated promoters. We assessed p27 and p53 expressions by immunohistochemistry. Loss of nuclear p27 expression {observed in 231 tumors (33%)} was significantly associated with CIMP-high, MSI-H and BRAF mutations, and these associations were much more pronounced among p53-negative tumors than p53-positive tumors. When CIMP-high and non-CIMP-high tumors were stratified by MSI status (or KRAS and BRAF status), CIMP-high and MSI-H (but not BRAF mutations) were still significantly associated with nuclear p27 loss. Nuclear p27 loss did not appear to be directly related to CDKN2A (p16) methylation. We conclude that downregulation of nuclear p27 is associated with CIMP-high and MSI-H in colorectal cancer. These associations are stronger among p53 wild-type tumors, implying important interplay of p27 and p53 functions (or dysfunctions) in the development of various molecular subtypes of colorectal cancer.
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PMID:Loss of nuclear p27 (CDKN1B/KIP1) in colorectal cancer is correlated with microsatellite instability and CIMP. 1708 68

p53 and the prostate-cancer-susceptibility gene RNASEL are tumour suppressor genes involved in apoptosis. We have previously reported that the common, functionally different variants Arg72Pro in p53 and Arg462Gln in RNASEL are associated with the age of disease onset of colorectal cancer in Lynch syndrome patients. To assess the combined effect of both variants, we screened 246 unrelated Lynch syndrome patients with a pathogenic germline mutation either in MSH2 (n=138) or in MLH1 (n=108) and colorectal cancer as first tumour, and 245 healthy controls. The global log rank test revealed significant differences in the age of disease onset for the genotypes of each variant (p=0.0176 for p53 and p=0.0358 for RNASEL) and for the combined genotypes of both variants (p=0.0174). The highest difference in median age of disease onset was seen between homozygotes for the wild-types in both genes (42years [range 22-75]) and homozygotes for the variant alleles in both genes (30years [range 26-47]). A multivariate Cox regression model indicated that only the p53 and RNASEL genotypes had a significant influence on age of disease onset (p=0.016 for p53 and p=0.014 for RNASEL) in an additive mode of inheritance, and that the effects of both variants are purely additive, which supports the notion that the p53 and RNaseL pathways do not interact. These findings may be relevant for preventive strategies in Lynch syndrome.
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PMID:The additive effect of p53 Arg72Pro and RNASEL Arg462Gln genotypes on age of disease onset in Lynch syndrome patients with pathogenic germline mutations in MSH2 or MLH1. 1722 35

Cytoplasmic mislocalization of p27 (CDKN1B/KIP1) is caused by activated AKT1 and has been associated with poor prognosis in various cancers. CIMP in colorectal cancer is characterized by extensive promoter methylation and is associated with MSI-MSI-H and BRAF mutations. We have recently shown a positive correlation between MSI/CIMP and loss of nuclear p27. However, no study has examined cytoplasmic p27 mislocalization in relation to CIMP and MSI in colorectal cancer. Using MethyLight assays, we quantified DNA methylation in 8 CIMP-specific gene promoters (CACNA1G, CDKN2A (p16), CRABP1, IGF2, MLH1, NEUROG1, RUNX3, and SOCS1) in 853 colorectal cancer samples obtained from 2 large prospective cohorts. We assessed expressions of nuclear and cytoplasmic p27 and nuclear p53 by immunohistochemistry. Cytoplasmic p27 expression was inversely associated with loss of nuclear p27 (P < .0001), CIMP-high (P < .0001), MSI-H (P < .0001), and BRAF mutations (P < .0001). The inverse association of cytoplasmic p27 with CIMP-high (or MSI-H) was independent of MSI (or CIMP) status. In addition, the inverse association of cytoplasmic p27 with CIMP-high was independent of KRAS/BRAF status. BRAF and CDKN2A (p16) methylation were not correlated with cytoplasmic p27 after stratification by CIMP status. The inverse associations of cytoplasmic p27 with MSI-H and CIMP-high were much more pronounced in p53-negative than p53-positive tumors. In conclusion, cytoplasmic p27 expression is inversely associated with MSI-H and CIMP-high, particularly in p53-negative tumors, suggesting interplay of functional losses of p27 and p53 in the development of various molecular subtypes of colorectal cancer.
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PMID:Cytoplasmic localization of p27 (cyclin-dependent kinase inhibitor 1B/KIP1) in colorectal cancer: inverse correlations with nuclear p27 loss, microsatellite instability, and CpG island methylator phenotype. 1723 30

We evaluated alterations in p53, PIK3CA, PTEN, CTNNB1 (beta-catenin), MLH1, and BRAF among common histological subsets of epithelial ovarian tumors to characterize patterns of alterations of different molecular pathways. There were 12 clear cell, 26 endometrioid, and 51 serous carcinomas evaluated by direct DNA sequencing for mutations in p53, PIK3CA, PTEN, BRAF, and CTNNB1. Methylation-specific polymerase chain reaction (PCR) assessed MLH1 promoter methylation status. Quantitative PCR identified PIK3CA amplification in 22 EC/CC and 94 SC. p53 mutations were identified in 25 (49%) of 51 SC, 11 (42%) of 26 EC, and 1 (8.3%) of 12 CC neoplasms and were more common in grade 3 EC (P = .045) and advanced-stage EC/CC (P = .007). PIK3CA mutations were identified in 3 (25%) of 12 CC, 3 (12%) of 26 EC, and 0 of 51 SC. PTEN mutations were significantly more common in EC (8/26, 31%) compared with CC (0/12; P = .04) and SC (2/51, 4%; P = .002). CTNNB1 mutations were identified, 6 (23%) EC and no CC or SC (P = .008). Both PTEN and CTNNB1 mutations were more common in low-grade EC/CC, whereas PIK3CA mutations occurred only in grade 3 cancers. PTEN and PIK3CA mutations were more common in p53 wild-type tumors (P = .003). PIK3CA amplification occurred in fewer EC/CC (0/22) versus SC (19/94, 20%; P = 0.02) and were slightly more common in p53 wild-type compared with p53 mutant SC (P = .08). Of 26 EC, 22 (85%) had a mutation in one of the genes studied compared with 4 33% of 12 CC (P = .003). Women with EC/CC had significantly better overall survival (P = .0008), and this remained significant after accounting for stage (P=.04). Mutations in p53 or in PTEN/PIK3CA are alternative pathways in ovarian carcinogenesis. Activation of PIK3CA occurs by gene amplification in SC but via somatic mutation of PIK3CA or PTEN in EC and CC. PIK3CA mutations are associated with high-grade tumors, whereas PTEN and CTNNB1 mutations are associated with low-grade tumors. Mutations in p53, PIK3CA, PTEN, and CTNNB1 account for most EC tumors; most CC remain unexplained. EC/CC histology is a favorable prognostic factor.
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PMID:Alternate molecular genetic pathways in ovarian carcinomas of common histological types. 1725 89


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