Paired analysis of tumour-derived versus blood-derived DNA to determine the prevalence of deleterious somatic variants in OC predisposition genes (<i>ATM</i>, <i>BRCA1/2, BRIP1</i>, <i>MSH2/6</i>, <i>PALB2</i>, <i>RAD51C/D</i> and <i>TP53</i>) and the <i>PIK3CA</i> and <i>PTEN</i> genes in individuals with OC (AGO-TR1 study, NCT02222883).
Clinicopathologic features and the expression pattern of MMR proteins (MLH1, MSH2, and MSH6) were characterized and analyzed in 32 synchronous primary endometrial and ovarian cancers.
The incidence of germline MMR gene mutations in ovarian cancer is only 2% but other mechanisms of gene inactivation mean that loss of expression of one of the seven main genes (MSH2, MSH3, MSH6, MLH1, MLH3, PMS1 and PMS2) occurs in up to 29% of cases.
Chromosome 2p21 (gene locus of hMSH2) was amplified in OC3/TAX300 cells. hMSH2 was overexpressed in 93.9 and 47.6% of paclitaxel-treated and untreated ovarian carcinoma tissue samples (P=0.0001), respectively. hMSH2 was overexpressed in 93.3 and 54.2% of low-differentiated and moderate-to-highly differentiated ovarian carcinoma tissue samples (P=0.0008), respectively. hMSH2 expression was inhibited in the OC3/TAX300 cells transfected with hMSH2 siRNA. hMSH2 siRNA increased paclitaxel sensitivity, inhibited OC3/TAX300 cell proliferation (G2/M arrest), and increased susceptibility to apoptosis. hMSH2 expression was upregulated in ovarian carcinoma cell lines and tissues after paclitaxel treatment. hMSH2 overexpression is related to paclitaxel resistance and poor prognosis.
Based on recent estimates that 11.7-16.6 % of women with ovarian cancer are BRCA carriers and 2 % are HNPCC carriers, results suggest under-identification of carriers and under-utilization of genetic services by providers and patients.
Our findings suggest that fewer than 1% of women with ovarian cancer harbour a germline mutation in the HNPCC genes, with overrepresentation of MSH6 mutations.
Besides, the methylation rates of hMSH2 were significantly higher in endometrioid adenocarcinoma tissues than in other pathological types of ovarian cancer.
Ovarian cancer (N = 72) had an lifetime risk of 6.7% (95% CI: 5.3-9.1); risks were higher in women born after the median year of birth (p < 0.008) and in members of MSH2 families (p < 0.006).
Besides, the methylation rates of hMSH2 were significantly higher in endometrioid adenocarcinoma tissues than in other pathological types of ovarian cancer.
Limiting genetic evaluation to women with synchronous endometrial and ovarian cancer who have a family history suggestive of HNPCC may appropriately identify women with Lynch syndrome.
To clarify the mechanism of acquired CDDP resistance in ovarian cancer, we compared the microsatellite instability (MSI) by the amplification of 10 microsatellite loci and immunohistochemical detection of hMSH2 and hMLH1 expression between the primary resected tumours and the secondary resected residual tumours after 5 or 6 courses of CDDP-based chemotherapy in the 24 cases of ovarian cancer.
We calculated age related risks of all, colorectal, endometrial, and ovarian cancers in nt943+3 A-->T MSH2 mutation carriers (n=76) for all patients and for men and women separately.
The fact that we found no germline pathologic mutations in hMSH2 and hMLH1 (predominant sites of mutation in HNPCC) in MIN+ OC cases, suggests that the genetic basis of MIN in OC can be different from that in HNPCC; our finding that distinct microsatellite banding patterns largely distinguish sporadic from familial OC, may reflect the involvement of different DNA repair genes in MIN in individual OC cases.
This review discusses recent insights into the roles of the p53 tumor-suppressor gene and growth factors in the development of ovarian cancer and describes the genes implicated in familial ovarian cancer syndromes related to the MSH2 (Lynch II) and BRCA1 (breast and ovarian cancer) genes.
Amongst the important known susceptibility genes are those dominant genes conferring a high risk of breast and ovarian cancer (BRCA1), colon cancer (hMSH2 and hMLH1), and melanoma (MLM).
The genetic instability observed in the tumor and cell line DNA, together with the germ-line mutation in a mismatch-repair gene, suggest that the MSH2 gene is involved in the onset and/or progression in a subset of ovarian cancer.