DNA Death Repair Gene RAD51 And MSH2 Synthesis Lethal Effect Study

Objective:To explore the lethal action and possible mechanism of RI-1,a RAD51 inhibitor,on MSH2 deficient colorectal cancer cells.Method:The first,the expression of MSH2 protein level was assessed by Western blot.Then,the sensibility of human colorectal cancer cells to RI-1(10,20,30,40 and 50?mol/L)was measured by MTT method.Lentivirus vectors MSH2-shRNA and Neg-shRNA(negative control)were constructed and transfected into HT29 cell.At last,apoptosis and DNA damage of cells treated with RI-1(40 ?mol/L)were detected by flow cytometry and Single cell gel electrophoresis respectively;In addition,the formation of?-H2AX foci was analyzed by immunofluorescence.Results:First,The expression level of MSH2 in HCT8 cell had significantly lower than the wild type HT29 cell,the sensitivity of RI-1 in them were different,and HCT8 cell treated with RI-1 had obviously apoptosis(P<0.01);Second,the change of homology MSH2 expression level in HT29 cell,found that HT29shMSH2 cells with MSH2 knocked down had more sensitive to RI-1 compared with control subject;and compared with the control group had obviously apoptosis phenomenon;Last,in HCT8 and HT29shMSH2 cells,tail DNA%,tail length,tail moment and olive tail moment were markedly increased(P<0.05),and the number of ?-H2AX focus were significantly increased(P<0.01).Conclusions:RAD51 inhibitor RI-1 selectively killed MSH2 deficient colorectal cancer cells by increasing DNA damage.