Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C1140680 (ovarian cancer)
 28,141 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Japanese breast cancer families were collected and classified into the following 7 types according to the onset age and the distribution of other cancers in the family lines; early-onset type, late-onset type, familial breast-ovarian cancer type, familial breast-prostate cancer type, familial breast-thyroid cancer type, familial male and female breast cancer type and multiple primary cancer type. We have detected no p53 germ line mutations in the patients from these families. Linkage with BRCA1 was not detected in any single families. These data indicate that neither BRCA1 or p53 is a major susceptible gene in Japanese familial breast cancer. However, in the two site-specific breast cancer families, the same nonsense mutation of the BRCA1 gene was detected.
 ...
PMID:[Familial breast cancer]. 853 41

An estimated 5 to 10% of all breast and ovarian cancer is attributable to inherited mutations in two highly penetrant autosomal dominant susceptibility genes, BRCA1 and BRCA2. BRCA1 confers higher risk of ovarian cancer and BRCA2 much higher risk of male breast cancer. With the exception of missense mutations in the RING finger near the amino terminus of BRCA1, virtually all germline mutations in the gene cause the novel BRCA1 protein to be prematurely truncated. Approximately 90% of breast tumors in BRCA1 families, 50% of unselected breast tumors and 65-80% of unselected ovarian tumors have lost one allele of BRCA1 by somatic deletion. Very few tumors have detectable somatic point mutations in BRCA1. Inhibition of BRCA1 expression in mammary epithelial cell lines also suggests that BRCA1 may act as a tumor suppressor. The biological function of BRCA1 is still unknown, although identification of a patient homozygous for an inherited BRCA1 mutation suggests that the gene's function may be essential only to specific tissues. At least two other genes, P53 and the androgen receptor, are responsible for inherited predisposition to breast cancer in rare families. Several epidemiologic studies suggest that individuals carrying rare alleles at a minisatellite flanking the HRAS locus are at increased risk of cancer, including breast cancer. Finally, preliminary epidemiologic studies also suggest that individuals heterozygous for mutations in the ataxia telangiectasia gene may be at increased risk of breast cancer.
 ...
PMID:Inherited breast and ovarian cancer. 854 81

Proliferative activity (PA) and p53 over-expression were assessed in 68 cases of primary ovarian epithelial tumors of variable grades of malignancy by immunohistochemical methods using antibodies to PCNA (proliferative cell nuclear antigen) and p53 molecule. First, we compared the values in benign tumors, tumors of borderline malignancy and malignant tumors. Malignant tumors possessed higher PA value (26.8 +/- 14.7%) than benign tumors (1.6 +/- 1.4%), and tumors of borderline malignancy exhibited an intermediate value (11.4 +/- 5.1%). Intranuclear accumulations of p53 product were more frequently observed in malignant tumors (16/32, 50%) than in tumors of borderline malignancy (3/9, 33%). None of the benign tumors exhibited p53 over-expression. In malignant tumors, PA correlated well with the histologic grade of tumors, although the histologic type and stage of the diseases did not correlate significantly with PA. Then, we focussed on the cases of malignant ovarian cancer composed of heterogeneous lesions showing a different grade of malignancy; invasive lesion (IL), non-invasive lesion (NIL), and benign appearing lesion (BAL). PA of NIL was almost identical with that of IL (19.6 +/- 13.5% vs. 23.3 +/- 12.6%), while BAL showed significantly lower PA (2.1 +/- 3.0%, p < 0.001) than the above two lesions and was similar to that of benign tumors. Furthermore, p53 over-expression was never observed in BAL, even in cases in which IL and/or NIL showed p53 over-expression. Thus, the results indicated that histologically benign-appearing lesions of malignant ovarian epithelial tumors possessed a biologic character similar to benign tumors. Collectively, all these findings would support the concept that a part of malignant ovarian epithelial tumors would be derived from benign tumors through progressive transformation.
 ...
PMID:Proliferative activity and p53 over-expression of ovarian epithelial tumors. 854 93

Targeting dysfunctional gene expression in the cancer cell with gene-specific therapeutics requires knowledge of the structure and expression of the designated gene. Because of the prevalence of p53 dysfunction in epithelial ovarian carcinoma, modulation of the expression of this tumor suppressor gene is an attractive target for gene therapy. We sequenced the p53 gene and analyzed its expression in 10 ovarian cancer cell lines. Only five cell line mutations were encountered, three associated with a loss of heterozygosity. Thus, neither p53 mutation nor allelic loss is required for ovarian carcinogenesis or propagation of ovarian cancer cell lines in vitro. SSCP screening, but not immunohistochemical staining, correlated with results of direct genomic sequencing. All p53 immunohistochemical-negative cell lines differed from that reported by another laboratory, underscoring the importance of the knowledge of target gene expression in a given cell line in a given laboratory. We designed pilot studies of antisense oligodeoxynucleotides directed against the p53 gene based on our sequence data. Differential growth inhibition of the A2780-CP-20 cell line (mutant p53 protein), but not of the OVCAR-3 cell line (wild-type p53 protein) confirmed the potential usefulness of this strategy.
 ...
PMID:p53 gene mutation analysis and antisense-mediated growth inhibition of human ovarian carcinoma cell lines. 855 31

P53 status may be a determinant of chemosensitivity of tumor cells; however, its involvement in cellular resistance to cisplatin remains uncertain. To investigate the relationships between p53 and the development of resistance to cisplatin, the p53 gene status was studied in ovarian carcinoma cell systems which included two cisplatin-resistant variants (IGROV-1/Pt 0.5 and IGROV-1/Pt 1) selected in vitro after prolonged drug exposure of the cisplatin-sensitive parental IGROV-1 cell line. IGROV-1/Pt 0.5 and IGROV-1/Pt 1 cell lines exhibited a degree of resistance of approximately 6 and 14, respectively, following 96-h exposure to the drug and were cross-resistant to other DNA-damaging agents (ionizing radiation and melphalan). Resistance to cisplatin paralleled a reduced cell susceptibility to cisplatin-induced apoptosis. DNA single-strand conformation polymorphism analysis of exons 5-9 demonstrated the presence of two mutants alleles at exon 8 in the two resistant cell lines, in contrast to the parental IGROV-1 cell line which exhibited the wild-type p53 gene. Direct DNA sequencing revealed that the mutations consist of two nucleotide changes in the DNA-binding domain at codons 270 (T/A) and 282 (C/T). The consecutive levels of p53 protein were lower in IGROV-1 than in IGROV-1/Pt cells. Following exposure to ionizing radiation or cisplatin, accumulation of the p53 protein was markedly enhanced only in the sensitive cells. Concomitantly, the expression of WAF-1 protein was strongly induced in the parental IGROV-1 cells, whereas WAF-1 protein remained undetectable in the IGROV-1/Pt 1 subline after DNA-damaging treatment. Consistent with this finding is the observation that ionizing radiation caused a different pattern of cell cycle perturbation in sensitive and resistant cells. Northern blot analysis demonstrated a marked reduction in bax mRNA levels in IGROV-1/Pt 1 cisplatin-resistant cells. Cotransfection assays with wild-type or mutant p53 expression plasmids and a reporter gene plasmid that utilized the bax gene promoter to drive transcription of chloramphenicol acetyltransferase were consistent with the role of p53 in regulation of bax expression in these cells. Taken together, these observations support a role for mutations of the p53 gene in the development of cisplatin resistance in ovarian cancer as a consequence of loss of the ability of p53 to transactivate bax, an apoptosis-inducing gene.
 ...
PMID:Association between cisplatin resistance and mutation of p53 gene and reduced bax expression in ovarian carcinoma cell systems. 856 71

Advanced ovarian cancer is characterized by poor prognosis and the development of resistance to chemotherapy. We have found that Bcl-2 and p53, two proteins implicated in the control of apoptosis, are differently expressed in the ovarian cell line A2780 and its cisplatin-resistant variant 2780CP, with the resistant line overexpressing both proteins. Transfection of the A2780 cells with a Bcl-2- or p53-expressing plasmid increases resistance to various drugs, including cisplatin, suggesting that Bcl-2 and p53 expression may influence the sensitivity of ovarian cancer cell lines to chemotherapy. Expression of these two proteins in vivo was determined by immunohistochemical staining of ovarian tumor biopsies from 70 patients. We found that Bcl-2 and p53 were expressed in 57 and 61% of specimens examined, respectively. Both p53 and Bcl-2 were found to be independent prognostic indicators of survival in ovarian cancer. Survival was poorer in patients with tumors expressing high levels of p53, whereas expression of Bcl-2 was associated with improved survival.
 ...
PMID:The prognostic significance of Bcl-2 and p53 expression in ovarian carcinoma. 861 69

To develop a mapping strategy for improved detection of p53 allelic loss associated with ovarian carcinoma, we utilized multiple intragenic polymorphisms and single-strand conformation polymorphism (SSCP) analysis. p53 allelotype distributions were defined for 80 ovarian cancer patients from germ-line DNA. All polymorphic sites studied had polymorphism information content (PIC) rates of greater than 0.25. Tumor loss of heterozygosity (LOH) was determined from informative polymorphisms and migratory shifts on SSCP screening of exons 5-9. Of the four polymorphisms analyzed, the intron 1 (alu) was the most informative (PIC = 0.66). A novel allele of 110 base pairs was found in 4.4% of our ovarian cancer cohort at this site. The intron 3 (16-base pair repeat) and intron 6 (MSP1) polymorphisms were in relative equilibrium; thus, we chose to use only the intron 3 polymorphic site in the mapping strategy. Family cancer history did not influence the allelotype distribution frequencies. Overall, 56 of 61 tumors (91.8%) were informative for allelic loss, and LOH was observed in 66.1 %. A reduction to homozygosity at the p53 locus did not correlate with familial or clinical factors. These observations are consistent with the multiple mechanisms by which p53 dysfunction can occur.
 ...
PMID:p53 allelotypes and enhanced detection of allelic loss in ovarian cancer: lack of correlation with familial and clinical factors. 862 30

Inactivation of the tumor suppressor gene p53 is frequently associated with ovarian cancer. Accumulation of stabilized p53 protein is a common feature in this tumor type. Underlying mutations in the p53 core region can lead to loss of the normal conformational state or loss of residues necessary for DNA binding and transcriptional regulation. Five HPV-free ovarian cancer cell lines established in our laboratory with and without immunocytochemically detectable p53 expression were selected for the correlation of subcellular localization of aberrant p53 and the type of gene mutation. The expression level regarding staining intensity and proportion of cells accumulating p53 was characterized employing an immunoreactive score. Two cell lines with point missense mutations in the core region showed strong nuclear or nuclear plus cytoplasmic staining. One cell line with exclusive staining of the cytoplasm contained a deletion of the major nuclear localization signal. Among two cell lines without p53 accumulation, one contained a microdeletion resulting in a frame shift, the other carried the wild-type sequence. The MDM2 oncogene was not amplified and its gene product was not overexpressed. In ovarian cancer, inactivated p53 can accumulate in both major cell compartments depending on the type of the underlying mutation.
 ...
PMID:Subcellular localization of accumulated p53 in ovarian cancer cells. 862 45

The p53 protein is a multifunctional transcriptional regulator involved in cellular response to DNA damage and has been implicated as a putative determinant of sensitivity of tumor cells to cytotoxic agents. Since the p53 gene becomes inactivated in over one-half of advanced ovarian carcinoma, in this study we have examined the relationships between p53 gene alterations, p53 immunoreactivity, and response to cisplatin-based chemotherapy in ovarian cancer patients. All patients had advanced (FIGO stage III or IV) ovarian carcinoma and, with one exception, were untreated at the time of collection of tumor specimens. After initial debulking surgery, patients received high-dose cisplatin therapy. Tumor samples were analyzed for p53 gene mutations and for p53 protein accumulation, and the findings were correlated with tumor responsiveness. Of the 33 tumors examined, p53 gene mutations were found in 20 cases, including 15 missense mutations, 2 deletions, 2 nonsense mutations, and a base substitution at splice site. Twenty tumors showed positive immunostaining for p53. Only missense mutations were associated with positive immunostaining. In addition, p53 overexpression was detected in five tumors in the absence of mutations. Most (12 of 14) of the missense mutations associated with p53 protein stabilization were found refractory to therapy, as well as tumors overexpressing wild-type p53 (4 of 5). A significant correlation has been found between p53 accumulation, type of mutation (i.e., missense mutations), and pathological response to cisplatin-based therapy. In conclusion, the present results are consistent with a role of p53 as a determinant of chemosensitivity of ovarian carcinoma.
 ...
PMID:A comparative study of p53 gene mutations, protein accumulation, and response to cisplatin-based chemotherapy in advanced ovarian carcinoma. 863 Sep 96

The aim of the present study was to determine the activity of a combined regimen of mitoxantrone (DHAD) and ifosfamide (IFO) and identify clinical and biological factors with prognostic importance for the second-line treatment of ovarian cancer. The following factors were investigated for their prognostic importance: age, disease sites, platinum responsiveness, histological grade, the presence of clinically/radiologically detectable versus not detectable disease, residual disease volume after first surgery, p53 protein, c-erbB-2 oncoprotein and laminin receptor. 72 patients entered the trial. DHAD and IFO therapy led to a 15% response rate among the 47 cases with clinically/radiologically detectable disease (1 complete and 6 partial responses), with a median response duration of 4 months. The response rate was significantly different according to platinum responsiveness (4% objective responses in platinum-resistant versus 27% in platinum-sensitive disease). The time to treatment failure (TTF) and overall survival (OS) were affected by the presence of clinically detectable disease at study entry (median TTF 4 months in the presence of clinically/radiologically detectable disease versus 9 months if the disease was not similarly detectable, P = 0.02; median OS 10 months versus 21 months, P = 0.01). Initially overexpressed in only a few tumours, the c-erbB-2 oncoprotein became overexpressed in 36% of platinum-resistant tumours; this modulation did not occur in platinum-sensitive tumours. Furthermore, laminin receptor was expressed in 77% of platinum-sensitive versus 39% of platinum-resistant patients. There were no differences in p53 protein expression according to drug responsiveness.
 ...
PMID:An I.T.M.O. group study on second-line treatment in advanced epithelial ovarian cancer: an attempt to identify clinical and biological factors determining prognosis. 865 51


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