Abstract: Objective To investigate the effect of siRNA targeting checkpoint kinase 1 (Chik1) on curcumin-induced apopotosis and cell cycle of human gastric cancer SGC7901 cells,so as to evaluate the role of Chk1 as a therapeutic target to sensitize human gastric cancer to curcumin.Methods The SGC7901 cells were transfected with siRNA-Chk1.The protein expression of Chk1 was detected by Western blotting.Cell cycle phase distribution and cell apoptosis were determined by flow cytometry (FCM). Results Compared with the control group,the Chk1 protein expression was significantly reduced in siRNA-Chk1 transfection group (P＜0.05).Further investigation revealed that the percentage of the G2/M phase cells of si-Chk1 group was lower of than that of the control group (P＜0.05) and the percentage of the G2/M phase cells was lower of than that of Empty vector+Curcumin group (P＜0.05).Transfection of si-Chk1 led to increased apoptotic rate from (14.7±1.1)% to (28.9±1.8)%. Conclusion Transfection of si-Chk1 decreased G2/M arrest and sensitized SGC7901 cells to curcumin-induced apoptosis,suggesting that Chk1 could be a potential therapeutic target to sensitize human gastric cancer to curcumin.