RI-1对MSH2缺陷结直肠癌细胞系的杀伤作用

摘要

目的探讨RAD51抑制剂RI-1对MSH2缺陷结直肠癌细胞系的杀伤作用及可能的作用机制.方法Western blot法筛选MSH2差异表达的结直肠癌细胞系,MTT法检测不同结直肠癌细胞系对RI-1(10、20、30、40 或50 μmol/L)的敏感性;构建针对MSH2基因的重组shRNA慢病毒表达载体并感染HT29细胞.RI-1(40 μmol/L)处理细胞,流式细胞术检测细胞凋亡的变化;单细胞凝胶电泳实验分析细胞内DNA损伤情况;细胞免疫荧光法检测γ-H2AX foci的形成.结果与对照组相比MSH2缺陷的HCT8细胞有明显细胞凋亡现象(P<0.01);HCT8细胞和HT29 Shmsh2细胞尾部DNA含量、尾长和尾距均较对照组明显增加(P<0.05);HCT8细胞和HT29 Shmsh2细胞内γ-H2AX foci的形成数量较对照组明显增加(P<0.01).结论RAD51抑制剂RI-1可能通过增加细胞内DNA损伤参与RI-1对MSH2缺陷肿瘤的杀伤作用.%Objective To explore the lethal action and possible mechanism of RI-1, a RAD51 inhibitor, on MSH2 deficient colorectal cancer cells.Methods The expression of MSH2 protein level was assessed by Western blot, and the sensibility of human colorectal cancer cells to RI-1 (10, 20, 30, 40 and 50 μmol/L)was measured by MTT method.Lentivirus vectors MSH2-shRNA and Neg-shRNA (negative control) were constructed and transfected into HT29 cell.Apoptosis and DNA damage of cells treated with RI-1(40 μmol/L)were detected by flow cytometry and Single cell gel electrophoresis respectively.In addition, the formation of γ-H2AX foci was analyzed by immunofluorescence.Results Compared with control, MSH2-deficient HCT8 cells had obviously apoptosis(P<0.01);in HCT8 and HT29 Shmsh2 cells, tail DNA%, tail length, tail moment and olive tail moment were markedly increased(P<0.05),and the number of γ-H2AX focus were increased(P<0.01).Conclusions RAD51 inhibitor RI-1 selectively kills MSH2 deficient colorectal cancer cells by increasing DNA damage.