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)

Numerous molecular genetic events occurring in the development of sporadic colorectal neoplasia have been previously defined. The most frequent genetic alterations are mutations of the APC, KRAS, and TP53 genes, as well as loss of the DCC gene and of the second TP53 allele. The data from several groups indicate that these genes play an important role in ulcerative colitis-associated dysplasias and cancer, as they do in sporadic colorectal adenomas and carcinomas. KRAS and TP53 mutations were detected in dysplasia, but also in villous regeneration and active colitis, and affect a subpopulation of the cells composing these lesions. We conclude that in histologically defined dysplasia, clones can be found that genetically represent precancerous lesions in ulcerative colitis. Seen in this way, part of the active colitis and villous regeneration lesions might be considered as preneoplastic. When present, KRAS mutation is an excellent genetic marker to map populations of preneoplastic cells.
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PMID:Molecular genetics of dysplasia in ulcerative colitis. 757 15

The four principal gut epithelial cell lineages undergo continuous and rapid renewal during a geographically well-organized migration along the crypt-to-villus axis. The molecules that regulate their proliferation and differentiation programs are largely unknown. The large tumor antigen (TAg) of wild-type (wt) simian virus 40 (SV40) and its mutant derivatives represent tools for describing the contributions of regulators of the cell cycle to the proliferative state of each lineage. Expression of SV40 TAgwt in postmitotic, villus-associated enterocytes of transgenic mice causes them to reenter the cell cycle without an apparent effect on their state of differentiation. When human KRAS with a Val-12 substitution ([Val12]KRAS) is coexpressed with SV40 TAgwt in villus enterocytes of bitransgenic animals, the two oncoproteins cooperate to produce dedifferentiation (dysplasia). SV40 mutant d11137 expresses a TAg that is unable to complex with p53 but retains N-terminal transforming functions, including the ability to complex pRB, p107, and p300. When SV40 TAgd11137 is expressed in villus enterocytes, they reenter into the cell cycle. However, coexpression of SV40 TAgd11137 and [Val12]KRAS does not produce dysplastic changes. Thus, the N-terminal 121 residues of TAg are sufficient to perturb the proliferative state of the enterocyte but not to produce detectable changes in the state of differentiation when coexpressed with [Val12]KRAS.
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PMID:Expression of wild-type and mutant simian virus 40 large tumor antigens in villus-associated enterocytes of transgenic mice. 804 20

A predisposition to colorectal cancer is shown to be linked to markers on chromosome 2 in some families. Molecular features of "familial" cancers were compared with those of sporadic colon cancers. Neither the familial nor sporadic cancers showed loss of heterozygosity for chromosome 2 markers, and the incidence of mutations in KRAS, P53, and APC was similar in the two groups of tumors. Most of the familial cancers, however, had widespread alterations in short repeated DNA sequences, suggesting that numerous replication errors had occurred during tumor development. Thirteen percent of sporadic cancers had identical abnormalities and these cancers shared biologic properties with the familial cases. These data suggest a mechanism for familial tumorigenesis different from that mediated by classic tumor suppressor genes.
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PMID:Clues to the pathogenesis of familial colorectal cancer. 848 15

Polycythemia vera (PV) and essential thrombocythemia (ET) are chronic myeloproliferative disorders that may progress to acute leukemia in a subset of patients. This study aimed at investigating the genetic lesions associated with the blastic transformation of PV and ET. A panel of PV and ET cases at different stages of disease was analyzed for the presence of genetic alterations of TP53, NRAS, KRAS, and MDM2 by a combination of mutational analysis and Southern blot hybridization. The occurrence of microsatellite instability (MSI) was also tasted in selected cases. Samples of PV and ET analyzed in chronic phase disease were consistently devoid of all genetic lesions tested, suggesting that alterations of TP53, NRAS, KRAS, and MDM2 do not contribute significantly to development of chronic phase PV and ET. Conversely, mutations of TP53 were detected in 7/15 (46.6%) blastic phase cases, including 3/5 PV and 4/10 ET. In blastic phase patients for whom the corresponding chronic phase DNA was also available, it could be documented that the genetic lesion had arisen at the time of blastic transformation. In addition to TP53 mutations, cases of blastic phase PV and ET occasionally harbored mutations of NRAS (one case of blastic phase ET) or displayed MSI (one case of blastic phase PV). These data indicate that inactivation of TP53 is a relatively frequent event associated with the blastic transformation of PV and ET and may be responsible for the tumor progression of these disorders.
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PMID:Genetic lesions associated with blastic transformation of polycythemia vera and essential thrombocythemia. 925 60

Our understanding of the molecular genetics of pancreatic cancer has advanced spectacularly over the last 5 years so that this tumour type is now one of the best characterised of all malignancies. A small proportion of cases results from inherited predisposition due to germline transmission of a mutated CDKN2 or BRCA2 gene, while patients with familial pancreatitis due to a mutated cationic trypsinogen gene have a greatly increased risk of developing pancreatic cancer. The majority of cases are sporadic and are characterised at the molecular level by several key genetic abnormalities. The most frequent of these is point mutation of the dominant oncogene KRAS, a lesion which occurs as an early and possibly initiating event in tumourigenesis. Inactivating mutations of the tumour suppressor genes TP53, CDKN2 and SMAD4 are also frequently observed and this constellation of genetic defects sets pancreatic cancer apart from other types of cancer, a feature which could have important implications for molecular diagnosis. Genetic intervention for cancer prevention and therapy is becoming a clinical reality and several approaches are being pursued for pancreatic cancer. As well as tumour suppressor gene replacement and oncogene blockade, strategies with a potential bystander effect are showing promise. These include genetic prodrug activation therapy using selective expression of suicide genes and genetic immunomodulation with cytokines and tumour-associated antigens.
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PMID:Molecular advances in pancreatic cancer. 943 1

The phenotypic variability of epithelial ovarian neoplasms correlates with a diversity of changes on the molecular level. Invasive serous and undifferentiated ovarian carcinomas are characterized by p53 mutations, extensive loss of genetic material of chromosome 17 and complex changes on many other chromosomes. These alterations are seen only in a minority of mucinous and endometrioid carcinomas, mainly in advanced stages. Overexpression of bcl-2 is seen most frequently in endometrioid carcinomas (ca. 90% of cases), which in addition show microsatellite instability in around a third of cases, as has been described in endometrioid endometrial carcinomas. KRAS mutations are characteristic for mucinous LMP tumors (borderline tumors) and mucinous carcinomas (40-50% of cases). Furthermore, KRAS mutations have been described in around a third of serous LMP tumors, which in addition show microsatellite instability in up to 40% of cases. Serous LMP tumors never harbour complex chromosomal aberrations.
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PMID:[Molecular genetics of epithelial ovarian neoplasms: correlations with phenotype and biological behavior]. 955 93

Two human cancer cell lines were established from metastatic lesions of an adenocarcinoma (RAL) and a squamous cell (CAEP) carcinoma of the lung. The clinical histories of the patients from whom the cell lines were derived are reported. The lines were maintained in continuous culture with doubling times of 65 (RAL) and 50 (CAEP) hours. The RAL and CAEP cell lines, whose morphology and ultrastructural features are presented, showed extensively rearranged karyotypes with modal number of 85 (RAL) and 98 (CAEP). In particular, chromosome 2 pentasomy and several clonal markers were evident in the RAL cells, whereas a telomeric deletion of chromosome 1, del (1)(q32), was observed in the CAEP cells. The morphologic data were confirmed by high expression of specific antigens for each histotype. A marked positivity of the neuron-specific enolase (NSE) levels was evident by immunoenzymatic assays in the cell lines cytosol with respect to those present in the respective patient's sera. No amplification or rearrangements were evident in the CMYC, LMYC, NMYC, INT-2, ERBB2, HRAS, KRAS, MOS, HST-1 genes by Southern blotting analysis in each cell line. Point mutations in exon 1 of KRAS and in exon 7 of TP53 were evident by polymerase chain reaction (PCR)-DNA sequencing in the RAL cell line, whereas no alterations were present in the HRAS and RB genes. The four genes studied did not show point mutations in the CAEP cell line. The RAL cell line was resistant to all the drugs tested, whereas the CAEP cells were sensitive to vinblastine. These cell lines may represent useful experimental models to investigate lung cancer biology and anticancer drug response.
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PMID:Molecular and biological features of two new human squamous and adenocarcinoma of the lung cell lines. 980 28

The phenotypic variability of epithelial ovarian neoplasms correlates with a diversity of changes at the molecular level. Invasive serous and undifferentiated ovarian carcinomas are characterized by p53 mutations with p53 protein accumulation, extensive loss of genetic material of chromosome 17 and complex changes on many other chromosomes, e.g. amplification of oncogenes. These alterations are seen only in a minority of mucinous and endometrioid carcinomas, mainly in advanced stages. Overexpression of bcl-2 is seen most frequently in endometrioid carcinomas (ca. 90% of cases), which in addition show microsatellite instability in around a third of the cases, as has been described in endometrioid endometrial carcinomas. KRAS mutations are characteristic for mucinous LMP tumors and mucinous carcinomas (40-50% of cases) and are also found in a third of serous LMP tumors. In addition, serous LMP tumors show mild microsatellite instability in 30%. However, complex chromosomal aberrations are never seen in these neoplasms.
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PMID:Molecular genetics of ovarian carcinomas. 998 71

There is evidence supporting a multistep genetic model for colorectal tumorigenesis. In familial adenomatosis polyposis (FAP), the inherited defect is a mutation in the APC gene. The vast majority of all sporadic colorectal cancers also show mutations in the APC gene, and the tumorigenesis in sporadic colorectal cancer and FAP is assumed to involve the same genes. Hereditary nonpolyposis colorectal cancer (HNPCC) is associated with germline mutations in DNA mismatch repair genes and, as a result of defective mismatch repair, microsatellite instability (MSI) is frequently seen. Tumorigenesis in HNPCC was first thought to involve mutations in the same genes as in FAP and sporadic colorectal cancer. Recently, however, an alternative pathway to development of colorectal cancer has been suggested in colorectal tumors with MSI, compared to those tumors without the MSI phenotype. We used a consecutive series of 191 sporadic colorectal cancers to find out if there were any differences between the two groups of tumors regarding the prevalence of mutations in the APC, KRAS, TP53, and TGFbetaR2 genes. As expected, 86% (19/22) of MSI-positive tumors showed a mutation in TGFbetaR2, while only one of 164 (0.6%) MSI-negative tumors did. A highly statistically significant negative association was found between MSI and alterations in APC and TP53. The MSI-positive tumors were screened for mutations in exon 3 of beta-catenin, which has been suggested to substitute for the APC mutation in the genesis of colorectal cancer, without finding mutations in any of the 22 MSI-positive tumors. The number of mutations found in KRAS was lower in MSI-positive than in MSI-negative tumors but the difference was not statistically significant. Our results strongly support the idea that carcinogenesis in MSI-positive and MSI-negative colorectal cancer develops through different pathways.
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PMID:Colorectal cancer with and without microsatellite instability involves different genes. 1050 23

The identification of several types of familial colorectal cancer has led to the discovery of some of the genes involved in these diseases. It was subsequently shown that somatic mutations of these genes (APC, mismatch repair genes, TP53, KRAS, and DCC) also occur in sporadic colorectal cancer. Gradually, this molecular information is being incorporated into the standard histopathological analysis of colorectal cancer and can be used for the characterization of primary tumors. Although attempts have been made to use molecular parameters to better define dysplasia grades, differentiate between adenoma and carcinoma, and subtype carcinomas, histological parameters remain the standard for the classification of primary tumors. Nonetheless, molecular parameters may help define subgroups of colorectal carcinoma differing in prognosis and requiring individualized treatment regimens. Interesting possibilities are predicting the response to chemotherapy or radiotherapy at a molecular level and the search for metastasis by looking for molecular markers in lymph nodes or circulating blood. Other pathological tests being developed include the detection of KRAS, TP53, or APC mutations in stool and plasma. Such approaches will have a significant impact on the clinical management of colorectal cancer.
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PMID:Molecular pathology of colorectal cancer. 1054


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