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

Recent evidence indicates that inherited and acquired genetic mutations are the driving force behind carcinogenesis and cellular transformation. This review examines a number of proto-oncogenes and tumor suppressor genes that are associated with ovarian carcinomas, including p53, BRCA1, and BRCA2; mismatch repair genes such as hMSH2 and hMLH1; and PTEN, HER-2/neu, K-ras, fms, and AKT2. Novel genes recently implicated in ovarian tumorigenesis are discussed, including NOEY2, OVCA1, and PIK3CA. Although no singular gene alteration has been shown to initiate transformation in the ovarian epithelium, elucidation of the complex molecular and cellular mechanisms involving these known gene mutations may result in new clinical management strategies.
 ...
PMID:Genetic factors in ovarian carcinoma. 1112 66

Molecular analysis of hereditary nonpolyposis colorectal carcinomas (HNPCC) has identified DNA mismatch repair deficiencies with resulting microsatellite instability (MSI) as a pathway of carcinogenesis that appears to be relevant for prognosis, treatment, and possibly prevention. In this study, expression of cell cycle proteins and other known prognostic markers is correlated with the microsatellite status of colorectal cancers (CRC). One hundred consecutive cases from the CRC Registry at Thomas Jefferson University were analyzed for MSI. Immunohistochemistry was performed for the mismatch repair proteins hMLH1 and hMSH2, tumor suppressor p53, apoptosis inhibitor bcl-2, cell cycle proteins p21(WAF1/CIP1), and p27 and the proliferation markers Ki-67 and topoisomerase II. High MSI (MSI-H) is significantly correlated with loss of either hMLH1 or hMSH2, presence of bcl-2, and absence of p53. p21(WAF1/CIP1) is positive in all tumors with MSI-H. Previous findings of a lower proliferation rate were confirmed with a topoisomerase II stain. Microsatellite stable (MSS) tumors generally express both MSH2 and MLH1. Other highly significant differences are positive p53 in 56% of MSS cases and negative bcl-2 in 98% of MSS cases. p27 expression is found in approximately 50% of all CRCs irrespective of the microsatellite status. MSI-H tumors follow the mutator pathway, with loss of expression of one mismatch repair protein, wild-type p53, lower proliferation, and positivity for p21(WAF1/CIP1). MSS tumors follow the suppressor pathway, characterized by p53 overexpression, higher proliferation, and absence of bcl-2 expression; p21(WAF1/CIP1) expression can be variable. These data provide a molecular basis for the clinical observation that patients with HNPCC appear to have a more favorable prognosis. HUM PATHOL 31:1506-1514.
 ...
PMID:Colorectal carcinomas with high microsatellite instability: defining a distinct immunologic and molecular entity with respect to prognostic markers. 1115 Mar 76

Carcinogenesis results from an accumulation of several genetic alterations. Mutations in the p53 gene are frequent and occur at an early stage of lung carcinogenesis. Loss of multiple chromosomal regions is another genetic alteration frequently found in lung tumours. We have examined the association between p53 mutations, loss of heterozygosity (LOH) at frequently deleted loci in lung cancer, and tobacco exposure in 165 tumours from non-small cell lung cancer (NSCLC) patients. A highly significant association between p53 mutations and deletions on 3p, 5q, 9p, 11p and 17p was found. There was also a significant correlation between deletions at these loci. 86% of the tumours with concordant deletion in the 4 most involved loci (3p21, 5q11-13, 9p21 and 17p13) had p53 mutations as compared to only 8% of the tumours without deletions at the corresponding loci (P< 0.0001). Data were also examined in relation to smoking status of the patients and histology of the tumours. The frequency of deletions was significantly higher among smokers as compared to non-smokers. This difference was significant for the 3p21.3 (hMLH1 locus), 3p14.2 (FHIT locus), 5q11-13 (hMSH3 locus) and 9p21 (D9S157 locus). Tumours with deletions at the hMLH1 locus had higher levels of hydrophobic DNA adducts. Deletions were more common in squamous cell carcinomas than in adenocarcinomas. Covariate analysis revealed that histological type and p53 mutations were significant and independent parameters for predicting LOH status at several loci. In the pathogenesis of NSCLC exposure to tobacco carcinogens in addition to clonal selection may be the driving force in these alterations.
 ...
PMID:Loss of heterozygosity is related to p53 mutations and smoking in lung cancer. 1116 81

This review focuses on the functional role and structural features of the genes involved in common hereditary cancers. Most of these tumors are sporadic and the genetic alterations responsible for their genesis take place over several cell generations; nevertheless, 5 to 10% of the human tumors are hereditary, with a rapid development. Cancer susceptibility genes have been classified as "gatekeepers" (e.g. RB1, ki-ras) and "caretakers" (e.g. hMLH1 and hMSH2, BRCA1). The first step in identifying individuals at high risk of developing a specific inherited form of cancer, and who should therefore undergo genetic tests, is the detailed construction of family history (an accurate cancer family history that includes at least three generation pedigrees, an appropriate cancer risk assessment and an effective genetic counseling). At present, the most useful methods of risk assessment are those performed on the following genes: BRCA1 and BRCA2 especially for hereditary breast and ovarian cancer, hMLH1 and hMSH2 for hereditary non polyposis colorectal cancer, APC for familial adenomatous polyposis, ret for medullary thyroid carcinoma, p53 for the Li-Fraumeni syndrome, p16 for melanoma and RB1 for retinoblastoma. In conclusion, the development of new diagnostic tests will permit a more accurate assessment of risk in individuals who have not so far shown any sign or symptom of the disease.
 ...
PMID:Hereditary common cancers: molecular and clinical genetics. 1120 30

The short arm of chromosome 3 is thought to harbor a novel oncogenic locus that is important in the genesis of lung cancer. The region at 3p21 is believed to contain a distinct locus that is sensitive to loss from the action of tobacco smoke carcinogens and has been reported to be specifically targeted for deletion in lung cancer. To investigate whether 3p21 alteration in lung cancer is associated with carcinogen exposure, PCR-based analysis was performed to detect loss of heterozygosity (LOH) on chromosome 3 at 3p21 in non-small cell lung carcinoma (NSCLC). We also measured instability at the BAT-26 locus, because the mismatch DNA repair gene, hMLH1, is found at 3p21. LOH at 3p21 was analyzed for association with the clinical features of NSCLC, p53 mutation status, polynuclear aromatic hydrocarbon-DNA adduct levels (measured using 32P-postlabeling) and carcinogen exposure information including cigarette smoking and asbestos exposure. Of 219 lung cancers, 150 cases (68.5%) were informative at the D3S1478 locus, and 44.2% of squamous cell carcinoma cases and 30.2% of adenocarcinoma cases showed 3p21 LOH. None of the cancers showed BAT-26 instability. The prevalence of 3p21 LOH was higher in both current and former smokers compared with never smokers and was higher in p53 mutated cases. Among squamous cell carcinoma cases, there was a strong association of increased 3p21 LOH with increasing polynuclear aromatic hydrocarbon-DNA adducts levels (P = 0.03), as well as an increased prevalence LOH with earlier age of smoking initiation (P = 0.02). Our results confirm that 3p21 LOH is strongly associated with measures of biologically effective dose of exposure to tobacco carcinogens. Our results also suggest that alterations of hMLH1 are not related to any of the reported associations, because there was no evidence of microsatellite instability. Finally, LOH in 3p21 may be an early molecular event in NSCLC, because it is significantly associated with a tendency to start smoking at a young age.
 ...
PMID:Tobacco smoke-induced DNA damage and an early age of smoking initiation induce chromosome loss at 3p21 in lung cancer. 1121 58

Genetic and epigenetic alterations of multiple cancer-related genes and molecules are implicated in the development and progression of human gastric carcinomas. Reactivation of telomerase, inactivation of p53 tumor suppressor gene, overexpression of cyclin E, and reduced expression of p27 KIP1 by disorganized degradation in proteasome are common events of both well-differentiated and poorly differentiated gastric adenocarcinomas. Inactivation of hMLH1 mismatch repair gene by CpG hypermethylation resulting in microsatellite instability, amplification of c-erbB2 oncogene, inactivation of APC tumor suppressor gene, and K-ras mutations are preferentially associated with well-differentiated gastric cancer. Conversely, reduction or loss of E-cadherin and catenins by both mutation and CpG hypermethylation and K-sam and c-met oncogene amplification are necessary for the development and progression of poorly differentiated or scirrhous gastric carcinomas. Interaction between cancer cells expressing c-met and hepatocyte growth factor from stromal cells is implicated in morphogenesis of gastric cancer.
 ...
PMID:Genetic and epigenetic changes in stomach cancer. 1124 97

The histologic distinction between benign and malignant Phyllodes tumors (PT) is often difficult and arbitrary. We analyzed a group of benign and malignant PT to determine whether specific histologic features and expression of Ki-67 and p53 could be useful in distinguishing benign PT from malignant tumors. We also determined whether deletions in Chromosome 3p at the FHIT and hMLH1 loci are common abnormalities in PT. Twenty PT were histologically classified as benign (7) or malignant (13). Seven of the malignant PT were low grade, and six were high grade. Ki-67 and p53 immunohistochemistry was performed on all tumors and analyzed for the stromal and for the epithelial component. PCR-based loss of heterozygosity analyses were performed with the following markers on Chromosome 3p: D3S1478 (3p21.2--21.3), D3S1289 (3p21.1--21.2), and D3S1295 (3p14.3--21.1). The distribution of immunoreactivity for Ki-67 was analyzed by quantifying the percentage of positive nuclei and expressed as the labeling index (LI). Patients' ages ranged from 13 to 71 years (median: 51 y). After a mean follow-up period of 8 years, none of the PT metastasized, whereas three recurred locally. Although malignant PT were larger than benign PT (means, 7.1 versus 4.3 cm), this difference was not statistically significant. Five tumors had infiltrating margins, and 14 were circumscribed. The Ki-67 LI in low-grade malignant PT (16 +/- 25.5) was significantly higher than that in benign PT (3.6 +/- 4.8), whereas the LI in the high-grade malignant PT group (50 +/- 21.9) was significantly higher than that in low-grade malignant tumors (P =.012). The Ki-67 LI in the three tumors that recurred was less than 10%. Two of seven (29%) benign PT were focally positive for p53, whereas four of seven (57%) low-grade malignant and three of six (50%) high-grade malignant PT were diffusely positive for p53. The three tumors that recurred initially were histologically benign, as were two of the recurrences. One recurrent tumor evolved to a high-grade malignant PT. Margins were greater than 1 cm in all tumors except four, three of which recurred locally. No allelic loss of 3p was found. In summary, Ki-67 expression may assist in distinguishing benign from malignant PT in diagnostically difficult cases. 3p deletions do not play a significant role in the development of these tumors. Neither Ki-67 nor p53 can reliably predict recurrence. Histologically high-grade malignant PT have a favorable prognosis if widely excised. We emphasize the importance of adequate margins in the treatment of benign and malignant PT.
 ...
PMID:Pathologic, immunohistochemical, and molecular features of benign and malignant phyllodes tumors of the breast. 1126 24

Colorectal adenomas can be morphologically classified as exophytic or flat. Polypoid cancers and cancers arising de novo (ie., without any adenomatous component) might be the results of genetic progression from exophytic and flat adenomas, respectively. In this study, we examined 94 morphologically distinct neoplastic specimens for mutations in K-RAS and analyzed 10 microsatellite loci tightly linked to the tumor suppressor genes APC, p53, DCC/SMAD4, hMSH2, and hMLH1. K-RAS mutations were significantly associated with exophytic adenomas [11 of 21 (52%)] compared to flat adenomas [2 of 13(15%), P < 0.03] and polypoid cancers [17 of 25 (68%)] compared to cancers arising de novo [7 of 25 (28%), P < 0.01]. Two polypoid cancer cases demonstrated three and four different K-RAS mutations, respectively, suggesting multiple areas of clonal expansion. Cancers arising de novo were significantly associated with loss of heterozygosity (LOH) at chromosome 3p compared to pol ypoid cancers [6 of 18(33%) versus 1 of 20(5%), P < 0.03], whereas the prevalence of LOH at chromosomes 2p, 5q, 17p, and 18q and microsatellite instability were not different between the groups. For all cancers, LOH at chromosomes 17p and 18q occurred in 47 and 51%, respectively. However, LOH at 17p and 18q occurred in 0 and 16% of benign lesions, respectively, suggesting their role in malignant transformation. There was no difference in LOH at chromosomes 17p and 18q between exophytic and flat lesions. These findings suggest that (a) mutant K-RAS is associated with the exophytic growth of colonic neoplasms, and that (b) some colorectal cancers arising de novo lose chromosome 3p during their evolution, which is not seen in polypoid cancers. Half of all cancers lose chromosomes 17p and 18q at or near the malignant transition of benign lesions as reported previously, irrespective of morphology. There may be more than one genetic avenue for colorectal cancer formation, and this correlates with the morphological characteristics.
 ...
PMID:Genetic pathways in the evolution of morphologically distinct colorectal neoplasms. 1128 47

The incidences of microsatellite instability (MSI) and underlying DNA mismatch repair (MMR) defects in pancreatic carcinogenesis have not been well established. We analyzed 100 sporadic and 3 hereditary pancreatic ductal adenocarcinomas for MSI, and high-frequency MSI (MSI-H) and low-frequency MSI (MSI-L) tumors were further analyzed for frameshift mutations of possible target genes and for promoter methylation and mutation of DNA MMR genes, including hMLH1, hMSH2, hMSH3, and hMSH6 genes. Among the 100 sporadic tumors, 13 (13%) were MSI-H, 13 (13%) were MSI-L, and 74 (74%) were microsatellite stable (MSS) tumors. All of the three hereditary tumors from hereditary nonpolyposis colorectal cancer (HNPCC) patients were MSI-H. MSI-H tumors were significantly associated with poor differentiation and the presence of wild-type K-RAS and p53 genes. Patients with MSI-H tumors had a significantly longer overall survival time than did those with MSI-L or MSS tumors (P = 0.0057). Frameshift mutations of hMSH3, hMLH3, BRCA-2, TGF-beta type II receptor, and BAX genes were detected in MSI-H tumors. Hypermethylation of the hMLH1 promoter was observed in 6 (46%) of the 13 sporadic MSI-H tumors but not in any of the 3 hereditary MSI-H tumors or 13 MSI-L tumors. All of the 3 HNPCC cases had germ-line hMLH1 mutation accompanied by loss of heterogeneity or other mutation in the tumor. Our results suggest that pancreatic carcinomas with MSI-H represent a distinctive oncogenic pathway because they exhibit peculiar clinical, pathological, and molecular characteristics. Our results also suggest the principal involvement of epigenetic or genetic inactivation of the hMLH1 gene in the pathogenesis of pancreatic carcinoma with MSI-H.
 ...
PMID:Genetic and clinical features of human pancreatic ductal adenocarcinomas with widespread microsatellite instability. 1130 99

The methylation status of seven cancer-related genes was investigated in a series of 58 colorectal cancers, 18 of which showed the microsatellite instability (MSI+) phenotype. Methylation of the hMLH1, p16 and MDR1 genes was found in 23, 29 and 28% of tumors, respectively. None of the tumors showed methylation of the TS, ATM, PARP or p21 genes. Methylation of the hMLH1, p16 and MDR1 genes was more frequent and more concordant in MSI+ compared to MSI- tumors (P<0.001) and was also strongly associated with poor histological differentiation (P<0.001). There were trends for associations between methylation at one or more of these loci and proximal tumor location, advanced Dukes' stage and the presence of wild-type p53 (P=0.06 for each).
 ...
PMID:Methylation of the hMLH1, p16, and MDR1 genes in colorectal carcinoma: associations with clinicopathological features. 1132 3


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>