Objective:To study the expression of the antisen se Ku70 in a human's lung carcinoma cell line(LCA) and its high-radiosensitivit y.Methods:The expression of the Ku70 protein in the Ku70- LCA and its radiosensitivity was detected by Western-blott ing and Cell Radiosensitivity Taste (to see The Cell Clonogenic Assay and Surviv al Curves).Results:(1)Only the sense Ku70 protein was defe cted in the Ku70-LCA,but the sense Ku70 protein wasn't defected in the Ku70as -LCA by Western-blotting.(2)The radiosensitivity was increased in the Ku70as- LCA and their radiosensitivity depend on the radiating dose(P＜0.01).Conclusion:After the expression of sense Ku70 protein in t he Ku70as-LCA was blocked by antisense Ku70,the Ku70as-LCA should be high-rad iosensitivit y,the Ku70 is a candiate target for cancer gene therapy.It was the first step fo r the study of tumor's specific radiating and gene therapy in the future.