First, the alterations (deletion/methylation/expression) of MLH1 and MSH2 were analyzed in 45 neoadjuvant chemotherapy (NACT)-treated and 133 pretherapeutic BC samples.
Statistical analysis demonstrated that MLH1 and MSH2 deficiency may lead breast cancer progression to advanced stage, correlated with tumor focality (MLH1 P = 0.001; MSH2 P = 0.002) and chemotherapy (MLH1 P = 0.01; MSH2 P = 0.04).
While variants in the MSH2 gene are known to be linked with an elevated cancer risk, the MSH2 gene is not a part of the standard kit for testing patients for elevated breast cancer risk.
When evaluating by gene, the age-standardized breast cancer risks for MSH6 (SIR = 2.11; 95% confidence interval (CI), 1.56-2.86) and PMS2 (SIR = 2.92; 95% CI, 2.17-3.92) were associated with a statistically significant risk for breast cancer whereas no association was observed for MLH1 (SIR = 0.87; 95% CI, 0.42-1.83) or MSH2 (SIR = 1.22; 95% CI, 0.72-2.06).
An increase in breast cancer risk was observed for women with the MUTYH_rs3219489 variant allele (odds ratio (OR)=2.23, 95% confidence interval (CI)=1.10-4.52) and for women with the MSH2_rs2303428 variant allele (OR=1.73, 95% CI=1.00-2.99).
Germ line mutations in genes involved in hereditary cancer syndromes, such as BRCA1 and BRCA2 in breast cancer and MSH2, MSH6, MLH1, and PSM2 in hereditary nonpolyposis colorectal cancer (HNPCC, more recently indicated as Lynch syndrome), confer a high risk to develop cancer.
On contrast to endometrial and ovarian cancer, which occurred significantly more often and at younger age in MLH1/MSH2 mutation carriers (median 50.5 and 49.0 years; P < 0.00001), overall cumulative breast cancer incidence closely mirrored the one in the Swiss population (56.5 years).
Decrease in the expression levels of TOP2A, MSH2 and MLH1 may play significant roles in the development of chemotherapeutic resistance to etoposide in breast cancer.
To our knowledge, this is the first report to find an association between MSH2 and MSH3 genetic variants and the development of radiosensitivity in breast cancer patients.
In this study, we reported that TGF-β downregulated the mutS homolog 2 (MSH2), a central component of the DNA mismatch repair (MMR) system, in HER2-transformed MCF10A mammary epithelial cells and in breast cancer (BC) cells.
In this study, we analyzed the promoter methylation of potent mismatch repair genes (hmlh1 and hmsh2) for the first time in 232 Indian patients with primary breast cancer (using methylation-specific polymerase chain reaction and expressional analysis).
Extensive screening of 59 multiple-case breast cancer families did not identify any coding region mutations or larger genomic alterations in MSH2 that might implicate MSH2 as a breast cancer susceptibility gene.
The elevated incidence of breast cancer and its association with a novel hMSH2 mutation bring to consideration the inclusion of this malignancy as part of the syndrome.
Therefore, MMR may play a role in the breast carcinogenesis and the Gly322Asp polymorphism of the hMSH2 gene may be considered as a potential marker in breast cancer.
To address these issues, 83 archival breast cancer specimens were examined for expression of hMSH2 and hMLH1 by immunohistochemistry and the relationship between MMR protein expression and patient clinical background was analyzed.
The presence of hMSH2 and p53 alterations in the same tumor suggests that the two oncoproteins act through a common mutational pathway, whereas the absence of a correlation between hMSH2 and MSI suggests that oncogenetic mechanisms of progression in primary breast cancer differ from those in HNPCC.