High Expression of MRE11-RAD50-NBS1 Is Associated with Poor Prognosis and Chemoresistance in Gastric Cancer

Background: The MRN complex of meiotic recombination 11 (MRE11), DNA repair protein Rad50 (RAD50) and Nijmegen breakage syndrome 1 (NBS1) proteins coordinate the detection and repair of DNA double-strand breaks (DSBs). DNA DSB repair-dependent chemoresistance likely has an effect on the treatment of human cancer. Materials and Methods: We investigated the expression of MRN complex in human gastric cancer (GC) tissues using immunohistochemistry and analyzed its clinical significance and prognostic relevance. Results: The expression of MRN complex was significantly associated with clinical factors including poorer prognosis and negatively associated with the expression of DNA damage marker phosphorylated H2A histone family, member X (gamma H2AX) in the nucleus. In the biopsy specimens, low expression of MRE11 correlated with good response to chemotherapy and surgical resection after down-staging by chemotherapy. Furthermore, the expression levels of MRE11 and RAD50 were independent predictors of surgical resection after chemotherapy. Conclusion: The high expression of MRN complex constituents could be a predictor for poor prognosis and chemoresistance in GC.