Objective To study the effect of DNA-PKcs blocking on the expression of autophagic proteins,and proliferation of esophageal squamous cell carcinoma cells(EC109)after irradiation(X-Ray).Methods NU7441 was used to inhibit DNA-PKcs and X-Ray radiation treatment were used to treat EC109 cells.Th experiment was divided into 4 groups,including control group, NU7441 group,X-Ray group,X-Ray+ NU7441 group.The expressions of autophagy protein Beclin-1 and LC3B were detected by Western blot.Apoptosis was detected by flow cytometry.MTT assay was used to detect cell proliferation.Results The expression of p-DNA-PKcs in EC109 cells was decreased after NU7441 treatment and increased after X-ray irradiation.Compared with untreat-ed cells(control group),the expressions of both Beclin-1 and LC3B in X-Ray+NU7441 group were increased.Compared with the X-Ray group,the expression of Beclin-1 in the X-Ray+NU7441 group was increased.Compared with the control group,the apoptotic rate of EC109 cells in the X-Ray group and X-Ray+NU7441 group was significantly increased,the difference was statistically significant(P<0.05).Compared with the X-Ray group the apoptosis rate in the X-Ray-NU7441 group was significantly increased.The MTT results showed that compared with the control group,the proliferation in the X-Ray group and X-Ray+NU7441 group was significantly inhibited, the difference was statistically significant(P<0.05).Conclusion NU7441 inhibits the expression of DNA-PKcs protein in EC109 cells, which could promote the expressions of autophagy protein Beclin-1 and LC3B,promotes apoptosis and inhibits cell proliferation.