Abstract: To explore the influence of Bcl2 gene expression by RNAi on the radiosensitivity of human lung adenocarcinoma cell line A549. MethodsVectors containing SiRNA targeting Bcl2 gene were constructed and transfected into A549. Real time RTPCR and Western blot were used to compare the efficiency of gene silencing. Flow cytometry was used to determine the effects of pBcl2siRNA and radiation on apoptosis. D0 and Dq of four cell lines were calculated by Clone formation array, and radiosensitivity of A549/Bcl2Ins was evaluated also by Clone formation array. ResultsThree stable transfected cell lines A549/Bcl2Ins, A549/ Bcl2Neg and A549/SD were screened from the transfected A549 cells. Western blot analysis and real time RTPCR indicated that expression of Bcl2 was suppressed by pBcl2siRNA. The apoptosis rate of A549/Bcl2Ins was higher than that of the controls, and the apoptosis rate of A549/Bcl2Ins at 6Gy irradiation was higher than that of the controls and the unirradiated groups. D0 and Dq of A549/Bcl2Ins were 1.399 and 1.298, respectively, lower than those of A549/ Bcl2Neg(1.695 and 2.480) or those of A549/SD(1.706 and 2.227) or those of A549(1.816 and 2.777). ConclusionRNAi could inhibit Bcl2 gene expression and enhances radiosensitivity of A549 cells.

Key words: Lung neoplasms, Genes, Apoptosis, Radiation tolerance, RNA interference