The Contribution of Tissue Inhibitor of Metalloproteinase-2 Genotypes to Breast Cancer Risk in Taiwan

Tissue inhibitor of metalloproteinase-2 (TIMP-2) is an endogenous inhibitor of matrix metalloproteinase-2 and is highly expressed in breast cancer (BC) cases at diagnosis. However, the genetic investigations for the association of TIMP-2 genotypes with BC risk are rather limited. In this study, contribution of TIMP-2 rs8179090, rs4789936, rs2009196 and rs7342880 genotypes to BC risk was examined among Taiwan's BC population. TIMP-2 genotypic profiles were revealed among 1232 BC cases and 1232 controls about their contribution to BC using a PCR-based RFLP methodology. The TIMP-2 rs8179090 homozygous variant CC genotype was significantly higher in BC cases than controls (odds ratio (OR) = 2.76, 95% confidence interval (95%CI) = 1.78-4.28, p = 0.0001). Allelic analysis showed that C allele carriers have increased risk for BC (OR = 1.39, 95%CI = 1.20-1.62, p = 0.0001). Genotypic together with allelic analysis showed that TIMP-2 rs4789936, rs2009196 or rs7342880 were not associated with BC risk. Stratification analysis showed that TIMP-2 rs8179090 genotypes were significantly associated with BC risk among younger (≤55) aged women, not among those of an elder (>55) age. Last, rs8179090 genotypes were also associated with triple negative BC. This study sheds light into the etiology of BC in Taiwanese women. Rs8179090 may be incorporated into polygenic risk scores and risk prediction models, which could aid in stratifying individuals for targeted breast cancer screening.

Polymorphisms in the MSH2 gene predict poor survival of North Indian lung cancer patients undergoing chemotherapy

Aim: To estimate if MSH2 polymorphisms, viz. rs63749993, rs2303425, rs2303426, rs4987188, rs2303428 and rs17217772, have any association with clinical outcomes in North Indian lung cancer patients. Materials & methods: PCR-RFLP was used for genotyping 500 cases. Logistic regression and survival analysis was performed by utilizing MedCalc software. Results & conclusion: Our study concluded, adenocarcinoma subjects having heterozygous genotype for rs2303425 have increased survival time (MST = 12.43, p = 0.03). In lung cancer patients undergoing paclitaxel therapy, heterozygous carriers for the rs17217772 polymorphism have reduced survival time (MST = 7.96 vs 2.63 months; HR = 2.09; p = 0.02). For rs63749993 polymorphism undergoing irinotecan therapy, subjects having mutant genotype showed poor survival (13.26 vs 6.06 months; HR = 5.37; p = 0.0004). The results suggest that MSH2 polymorphisms are involved in decreasing overall survival for patients undergoing platinum-based chemotherapy.

Correlation of MSH2 exonic deletions and protein downregulation with breast cancer biomarkers and outcome in Pakistani women/patients

Mismatch repair (MMR) pathway is one of the underlying mechanisms of predisposition to breast cancer (BC). The present study explored the association of MSH2 exonic deletions, respective survival analysis, protein structure prediction, transcription profiling, and expression analysis with BC risk. Genotyping analysis of 493 BC cases and 387 controls confirmed the association of two MSH2 exonic deletions, i.e., exon 3 (OR:6.4, CI = 3.4-12.1) and 9 (OR:7.8, CI = 4.1-14.8) with BC risk. In order to confirm the phenotypic-genotypic relationship, we have performed MSH2 transcriptomic (p < 0.05) and protein expression analysis (OR:30, CI = 4-230) which further confirmed its downregulation/loss in BC biopsy samples highlighting potential role in the onset of breast carcinogenesis. Additionally, we have presented that MSH2 mutations can alter the expression profile of other BC associated biomarkers like ER, PR, CK-7, GATA-3, and E-cadherin. Subsequently, the effect of exonic deletions on secondary structure of protein has shown missing of beta and alpha helices in their protein products via in-silico analysis. However, loss of exon 3 results in the altered core protein structure leading to dysfunction protein, possible cause of BC development. No association of MSH2 exonic deletions with survival statistics was observed conceivably due to the shorter follow-up time. Thus, our results at genetic, transcriptomic, and proteomic levels confirmed the downregulated MSH2, emphasizing its potential contribution in MMR mechanisms for breast tumorigenesis. In conclusion, MSH2 deficiency may cause breast cancer development and progression.

DNA Mismatch Repair Gene Variants in Sporadic Solid Cancers

The phenotypic effects of single nucleotide polymorphisms (SNPs) in the development of sporadic solid cancers are still scarce. The aim of this review was to summarise and analyse published data on the associations between SNPs in mismatch repair genes and various cancers. The mismatch repair system plays a unique role in the control of the genetic integrity and it is often inactivated (germline and somatic mutations and hypermethylation) in cancer patients. Here, we focused on germline variants in mismatch repair genes and found the outcomes rather controversial: some SNPs are sometimes ascribed as protective, while other studies reported their pathological effects. Regarding the complexity of cancer as one disease, we attempted to ascertain if particular polymorphisms exert the effect in the same direction in the development and treatment of different malignancies, although it is still not straightforward to conclude whether polymorphisms always play a clear positive role or a negative one. Most recent and robust genome-wide studies suggest that risk of cancer is modulated by variants in mismatch repair genes, for example in colorectal cancer. Our study shows that rs1800734 in MLH1 or rs2303428 in MSH2 may influence the development of different malignancies. The lack of functional studies on many DNA mismatch repair SNPs as well as their interactions are not explored yet. Notably, the concerted action of more variants in one individual may be protective or harmful. Further, complex interactions of DNA mismatch repair variations with both the environment and microenvironment in the cancer pathogenesis will deserve further attention.

The Association Between hMLH1 and hMSH2 Polymorphisms and Renal Tumors in Northeastern China

Aim: Although hMLH1 and hMSH2 are closely associated with the development and drug resistance of multiple types of tumors, their role in renal tumors remains unclear. This study was designed to examine the relationship between renal tumor development and polymorphisms in the hMLH1 and hMSH2 genes. Methods: The study included 180 patients with renal tumors that were confirmed by pathological examination and 199 healthy controls. The clinical and pathological stages of the tumor samples were determined, and DNA was extracted from the peripheral blood of the subjects. Polymorphisms in the hMLH1 and hMSH2 loci were identified using the 1000 genomes database and the multiplex ligase detection method. Correlation analyses was performed using single nucleotide polymorphism tests. Results: 88.9% (160/180) of the tumor specimens were identified as clear cell renal cell carcinoma (CCRC) and 89.4% (161/180) were stage I carcinomas. Three hMLH1 and nine hMSH2 polymorphic sites were identified, and the frequency of the AA genotype of the hMSH2 rs2303424 variant was found to be significantly higher in the renal tumor group (odds ratio [OR] = 1.37, 95% confidence interval [CI]: 1.02-1.86) in the additive model (p = 0.029), the recessive model (p = 0.005), and codominant model (p = 0.02). Multiple testing corrections were performed and the differences between the clear cell carcinoma and control samples remained significant. Compared with the controls, the distribution of the GG genotype of the hMSH2 rs11886591 locus was significantly higher in the clear cell carcinoma group (OR = 0.80, 95% CI: 0.59-1.10, p = 0.04) after multiple testing corrections in the dominant model. Conclusion: The AA genotype at the rs2303424 locus and GG genotype at rs11886591 locus of the DNA repair gene hMSH2 were closely associated with the development of renal tumors. Further studies are needed on larger cohorts to confirm this correlation.

Rs2303428 of MSH2 Is Associated with Hepatocellular Carcinoma Prognosis in a Chinese Population

The defects of DNA repair genes may lead to genomic instability and cancer. As an important DNA mismatch repair gene that maintains genomic stability from DNA replication errors, genetic variants of mutS homolog 2 (MSH2) are associated with some cancers. In this study, 1021 hepatocellular carcinoma (HCC) cases and 1021 non-HCC controls from Guangxi were included to explore the association between MSH2 single-nucleotide polymorphisms (SNPs) and HCC. Among the eight MSH2 SNPs, only genotype distribution of rs2303428 was significantly different from HCC and non-HCC patients (p < 0.05). Moreover, CT, TT, and CT/TT genotype of rs2303428 could increase HCC risk [OR (95% CI) = 1.758 (1.195-2.657), 1.846 (1.213-2.896), and 1.823 (1.219-2.763), respectively] and decrease the survival time of HCC patients [codominant, HR (95% CI) = 1.267 (1.046-1.535); dominant, HR (95% CI) = 1.675 (1.162-2.414)]. In addition, rs2303428 was found to interact with HBV infection and family history to increase HCC risk by gene-environment analysis (p < 0.05). Finally, multivariate COX regression analysis showed that rs2303428, tumor number, tumor staging, and metastasis had a significant influence on HCC prognosis. Our results provide MSH2 SNP, rs2303428, as a new prognostic biomarker for HCC patients.

MutS-Homolog2 silencing generates tetraploid meiocytes in tomato (Solanum lycopersicum)

MSH2 is the core protein of MutS-homolog family involved in recognition and repair of the errors in the DNA. While other members of MutS-homolog family reportedly regulate mitochondrial stability, meiosis, and fertility, MSH2 is believed to participate mainly in mismatch repair. The search for polymorphism in MSH2 sequence in tomato accessions revealed both synonymous and nonsynonymous SNPs; however, SIFT algorithm predicted that none of the SNPs influenced MSH2 protein function. The silencing of MSH2 gene expression by RNAi led to phenotypic abnormalities in highly silenced lines, particularly in the stamens with highly reduced pollen formation. MSH2 silencing exacerbated formation of UV-B-induced thymine dimers and blocked light-induced repair of the dimers. The MSH2 silencing also affected the progression of male meiosis to a varying degree with either halt of meiosis at zygotene stage or formation of diploid tetrads. The immunostaining of male meiocytes with centromere localized CENPC (centromere protein C) antibody showed the presence of 48 univalent along with 24 bivalent chromosomes suggesting abnormal tetraploid meiosis. The mitotic cells of root tips of silenced lines showed diploid nuclei but lacked intervening cell plates leading to cells with syncytial nuclei. Thus, we speculate that tetraploid pollen mother cells may have arisen due to the fusion of syncytial nuclei before the onset of meiosis. It is likely that in addition to mismatch repair (MMR), MSH2 may have an additional role in regulating ploidy stability.