An association between the -41657 C/T polymorphism of X-ray repair cross-complementing 2 (XRCC2) gene and ovarian cancer

Functional genetic variants of GEN1 predict overall survival of Chinese epithelial ovarian cancer patients

BACKGROUND

Inherited variations in DNA double-strand break (DSB) repair pathway are known to influence ovarian cancer occurrence, progression and treatment response. Despite its significance, survival-associated genetic variants within the DSB pathway remain underexplored.

METHODS

In the present study, we performed a two-phase analysis of 19,290 single-nucleotide polymorphisms (SNPs) in 199 genes in the DSB repair pathway from a genome-wide association study (GWAS) dataset and explored their associations with overall survival (OS) in 1039 Han Chinese epithelial ovarian carcinoma (EOC) patients. After utilizing multivariate Cox regression analysis with bayesian false-discovery probability for multiple test correction, significant genetic variations were identified and subsequently underwent functional prediction and validation.

RESULTS

We discovered a significant association between poor overall survival and the functional variant GEN1 rs56070363 C > T (CT + TT vs. TT, adjusted hazard ratio (HR) = 2.50, P < 0.001). And the impact of GEN1 rs56070363 C > T on survival was attributed to its reduced binding affinity to hsa-miR-1287-5p and the resultant upregulation of GEN1 mRNA expression. Overexpression of GEN1 aggregated EOC cell proliferation, invasion and migration presumably by influencing the expression of immune inhibitory factors, thereby elevating the proportion of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) and then constructing an immunosuppressive tumor microenvironment.

CONCLUSIONS

In conclusion, GEN1 rs56070363 variant could serve as a potential predictive biomarker and chemotherapeutic target for improving the survival of EOC patients.

The association between single nucleotide polymorphisms and ovarian cancer risk: A systematic review and network meta-analysis

BACKGROUND

The relationship between single nucleotide polymorphisms (SNPs) and ovarian cancer (OC) risk remains controversial. This systematic review and network meta-analysis was aimed to determine the association between SNPs and OC risk.

METHODS

Several databases (PubMed, EMBASE, China National Knowledge Infrastructure, Wanfang databases, China Science and Technology Journal Database, and China Biology Medicine disc) were searched to summarize the association between SNPs and OC published throughout April 2021. Direct meta-analysis was used to identify SNPs that could predict the incidence of OC. Ranking probability resulting from network meta-analysis and the Thakkinstian's algorithm was used to select the most appropriate gene model. The false positive report probability (FPRP) and Venice criteria were further tested for credible relationships. Subgroup analysis was also carried out to explore whether there are racial differences.

RESULTS

A total of 63 genes and 92 SNPs were included in our study after careful consideration. Fok1 rs2228570 is likely a dominant risk factor for the development of OC compared to other selected genes. The dominant gene model of Fok1 rs2228570 (pooled OR = 1.158, 95% CI: 1.068-1.256) was determined to be the most suitable model with a FPRP <0.2 and moderate credibility.

CONCLUSIONS

Fok1 rs2228570 is closely linked to OC risk, and the dominant gene model is likely the most appropriate model for estimating OC susceptibility.

Analysis of the association between the XRCC2 rs3218536 polymorphism and ovarian cancer risk

INTRODUCTION

Results conflict on the association between the XRCC2 rs3218536 polymorphism and ovarian cancer risk, despite wide-ranging investigations. This meta-analysis examines whether the XRCC2 rs3218536 polymorphism is associated with ovarian cancer risk.

MATERIAL AND METHODS

Eligible case-control studies were searched in PubMed. We therefore performed a meta-analysis of 5,802 ovarian cancer cases and 9,390 controls from 7 articles published. The strength of association between XRCC2 rs3218536 polymorphism and ovarian cancer susceptibility was calculated using pooled odds ratios (ORs) with corresponding 95% confidence intervals (CIs).

RESULTS

No statistically significant associations between XRCC2 rs3218536 polymorphism and ovarian cancer risk were found in any genetic models. However, a significant relationship with ovarian cancer risk was discovered when the high quality studies were pooled in the meta-analysis (AA vs. GG: OR = 0.59, 95% CI: 0.37-0.94, p = 0.03; GA vs. GG: OR = 0.87, 95% CI: 0.78-0.96, p = 0.009; GA + AA vs. GG: OR = 0.85, 95% CI: 0.77-0.94, p = 0.003; AA vs. GG + GA: OR = 0.60, 95% CI: 0.38-0.95, p = 0.03).

CONCLUSIONS

This meta-analysis shows that the XRCC2 rs3218536 polymorphism was associated with ovarian cancer risk overall for high quality studies. Non-Caucasian groups and high quality studies should be further studied.

Polymorphism of DNA Repair Genes via Homologous Recombination (HR) in Ovarian Cancer

Ovarian cancer is one of the most common types of cancer in women. The repair system via homologous recombination repairs double-strand breaks (DSB) of DNA, which are the most mortal for cell, out of all DNA damages. The genes, which encode the double-strand break repairing proteins, are highly polymorphic and, taking into account the significance of the repaired defects for cancer development, it seems important to learn the role of the polymorphisms in ovarian cancer development. The aim of the study was to determine the relationship between DNA repair genes via homologous recombination (HR) and modulation of the risk of ovarian cancer. The following polymorphisms were analysed: XRCC3-Thr241Met (rs861539), XRCC2--41657C/T (rs718282), XRCC2-Arg188His (rs3218536), BRCA1-Q356R (rs1799950) and RAD51-135 G/C (rs1801320). The study group included 600 patients with ovarian cancer and 600 healthy controls. The PCR-RFLP (PCR-based restriction fragment length polymorphism) technique was applied for polymorphism analysis. Allele XRCC3-241Met (OR 0.85, 95%CI 0.72-0.99, p < 0.045), XRCC2-41657 T (OR 1.67, 95% CI 1.42-1.96, p < .0001), BRCA1-356R (OR 1.61; % CI 1.37-1.90, p < .0001) and RAD51-135C (OR 5.16; 95% CI 4.29-6.20, p < .0001) strongly correlated with the neoplastic disease. No relationship was observed between the studied polymorphisms and the cancer progression stage according to FIGO classification. The results indicate that polymorphisms of DNA repair genes via homologous recombination may be associated with the incidence of ovarian cancer. Further research on larger groups is warranted to determine the influence of above-mentioned genetic variants on ovarian cancer risk.

Associations between XRCC2 rs3218536 and ERCC2 rs13181 polymorphisms and ovarian cancer

Recent studies explored XRCC2 rs3218536 and ERCC2 rs13181 polymorphisms and ovarian cancer (OC) risk. However, the association between these two single nucleotide polymorphisms and OC risk remains conflicting. Thus, we conducted a comprehensive systematic review and meta-analysis to investigate the association. We searched the databases of PubMed, and Embase. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by using fixed-effect or random-effect models. 15 case-control studies published in 11 papers including 4,757 cases and 8,431 controls were included in this meta-analysis. No associations were obtained between XRCC2 rs3218536 and ERCC2 rs13181 polymorphisms and OC risk. Stratification analyses of Hardy–Weinberg equilibrium status indicated that rs3218536 polymorphism was associated with the decreased risk of OC when in analysis of combined HWE positive studies. In conclusion, this meta-analysis indicates that XRCC2 rs3218536 and ERCC2 rs13181 polymorphisms may not be associated with the risk of OC.

The biological effects and clinical implications of BRCA mutations: where do we go from here?

BRCA1 and BRCA2 are tumour-suppressor genes encoding proteins that are essential for the repair of DNA double-strand breaks by homologous recombination (HR). Cells that lack either BRCA1 or BRCA2 repair these lesions by alternative, more error-prone mechanisms. Individuals carrying germline pathogenic mutations in BRCA1 or BRCA2 are at highly elevated risk of developing breast and/or ovarian cancer. Genetic testing for germline pathogenic mutations in BRCA1 and BRCA2 has proved to be a valuable tool for determining eligibility for cancer screening and prevention programmes. In view of increasing evidence that the HR DNA repair pathway can also be disrupted by sequence variants in other genes, screening for other BRCA-like defects has potential implications for patient care. Additionally, there is a growing argument for directly testing tumours for pathogenic mutations in BRCA1, BRCA2 and other genes involved in HR-DNA repair as inactivation of these genes may be strictly somatic. Tumours in which HR-DNA repair is altered are most likely to respond to emerging targeted therapies, such as inhibitors of poly-ADP ribose polymerase. This review highlights the biological role of pathogenic BRCA mutations and other associated defects in DNA damage repair mechanisms in breast and ovarian cancer, with particular focus on implications for patient management strategies.