Objective:To identify the influence on radiosensitivity of lung glandular cancer cells when excisions repair cross-complementing group1(ERCC1) gene was silenced by targeted siR NA.Methods:siR NA which targeting to ERCC1 and control siR NA was designed and synthesized.The human lung glandular cancer SPC-A-1 cells was transfected.A total of 56 nude mice were divided into two groups,and two kinds of SPC-A-1 cells were transplanted to armpit of right forelimb,to establish the nude mice subcutaneous xenotransplanted tumor model of human lung glandular cancer cells.After the tumor was developed,the nude mice were randomly divided into four groups and accepted different doses of X-Ray radiation,then the change of tumor volume,survival time of mice in every group were recorded and the average lifetime was calculated.Twenty-one days later of X-ray experiment,two mice were taken and sacrificed in each group and the tumors organizations were stripped.The cell apoptosis rate and cell cycle distributions were obtained by FCM(flow cytometry).Results:The volume of tumor which ERCC1 gene was silenced was less than single irradiation group after X-ray irradiation,and the growth speed was slower and the lifetime of mice was lengthened as well(P<0.05).The cells apoptosis rate and the rate of G2/M cells which ERCC1 gene was silenced were higher than the same dose control group and the rate of G_1 cells were lower,which indicated that the cells could be stopped at G_2/M point,the cell proliferation was inhibited,the cell apoptosis was promoted and the radiation sensitivity was improved after the ERCC1 was silenced.Conclusions:The radiation sensitivity of lung glandular tumor could be improved after the ERCC1 gene was silenced by siR NA. Objective: To identify the influence on radiosensitivity of lung glandular cancer cells when excisions repair cross-complementing group 1 (ERCC1) gene was silenced by targeted siR NA. Methods: siR NA which targeting to ERCC1 and control siR NA was designed and synthesized.The human A total of 56 nude mice were divided into two groups, and two kinds of SPC-A-1 cells were transplanted to armpit of right forelimb, to establish the nude mice subcutaneous xenotransplanted tumor model of human lung glandular cancer cells. After the tumor was developed, the nude mice were randomly divided into four groups and accepted different doses of X-Ray radiation, then the change of tumor volume, survival time of mice in every group were recorded and the average lifetime was calculated.Twenty-one days later of X-ray experiment, two mice were taken and sacrificed in each group and the tumors organizations were stripped.The cell apoptosis rate and cell cycle distrib Results: The volume of tumor which ERCC1 gene was silenced was less than single irradiation group after X-ray irradiation, and the growth speed was slower and the lifetime of mice was lengthened as well (P <0.05). The cells apoptosis rate and the rate of G2 / M cells which ERCC1 gene was silenced were higher than the same dose control group and the rate of G_1 cells were lower, which indicated that the cells could be stopped at G_2 / M point, the cell proliferation was suppressed, the cell apoptosis was promoted and the radiation sensitivity was improved after the ERCC1 was silenced. Conlusions: The radiation sensitivity of lung glandular tumor could be improved after the ERCC1 gene was silenced by siR NA.