Objective To study the specific killing effect in human carcinoma cells aftercombination treatment of radiation and p53 gene regulated by a radiation-enhanced promoter.Methods Aplasmid pE6 (TATA)-p53 was constructed.After irradiation,the expression of P53 was detected withWestern blot assay,apoptosis was detected by Annexin V-FITC,and cell survival was detected byclonogenic assay then the sensitivity enhancement ratio (SER) was analyzed for HeLa and A549 cells.Results The expression of P53 were increased in the irradiated cells and 6 Gy irradiation triggered thestrongest activity.After p53 transfection,radiation-induced apoptosis was obviously enhanced incomparison with the control group without gene transfection (F =11.018,10.736,P ＜ 0.05).The SER ofp53-promoter was 2.36 for A549 cells and 2.56 for Hela cells.Conclusions The p53-plasmid promotercould induce apoptosis and enhance the radiosensitivity of tumor cells,which may provide a noveltherapeutic strategy for cancer treatment.