TY - JOUR T1 - Loss of MDC1 in Endometrial Carcinoma Is Associated With Loss of MRN Complex and MMR Deficiency JF - Anticancer Research JO - Anticancer Res SP - 6547 LP - 6553 DO - 10.21873/anticanres.13870 VL - 39 IS - 12 AU - DANAE MERENTITIS AU - BICH DOAN NGUYEN AU - ELEFTHERIOS P. SAMARTZIS AU - AURELIA NOSKE AU - SIMONE BRANDT AU - KONSTANTIN J. DEDES Y1 - 2019/12/01 UR - http://ar.iiarjournals.org/content/39/12/6547.abstract N2 - Aim: To evaluate the frequency of loss of mediator of DNA damage checkpoint protein 1 (MDC1) protein expression in endometrial cancer (EC) and to determine whether loss of MDC1 is associated with certain clinicopathological parameters. Materials and Methods: MDC1 expression was examined in 426 samples of EC. The nuclear immunoreactivity of the protein was defined as: negative, weak, moderate and strong. Results: Loss of MDC1 expression (defined as negative nuclear staining) was found in 8.9% (38/426) of ECs and was significantly associated with the loss of MRE11 homolog, double-strand break repair nuclease, RAD50 double-strand break repair protein and nibrin complex components. In addition, loss of expression of MDC1 showed a significant correlation with any mismatch repair deficiency, with endometrioid histological subtype and low tumour grading. Conclusion: Based on these findings, we suggest that MDC1 loss frequently occurs in ECs with microsatellite instability. Due to deficient homologous recombination DNA repair, MDC1-negative ECs might show an increased sensitivity to poly(ADP-ribose) polymerase-inhibitory therapy. ER -