Role of Smac in apoptosis of lung cancer cells A549 induced by Taxol.

Background: A series of structurally unique second mitochondria-derived activators of caspase (Smac) that act as antagonists of inhibitor of apoptosis proteins (IAPs) directly have been discovered and have been shown to promote chemotherapy-induced apoptosis. In this study, we investigate the role of Smac in Taxol-induced apoptosis of lung cancer cell in vitro. Methods: PcDNA3.1/Smac recombinants were transfected into the non-small cell lung cancer cell line A549. Smac expression was detected by RT-PCR and Western blot. The invasive ability of cells was examined. Flow cytometry was used to analyze apoptosis of cells induced by Taxol with Annexin V/PI double staining technique. Results: Smac expression was significantly higher in the PcDNA3.1/Smac recombinant group than in the untransfected group at mRNA and protein level (p<0.05) and lower invasion through a basal membrane was apparent after transfection (p<0.05). A small number of cells were promoted to apoptosis in the PcDNA3.1/Smac group. There were significant differences compared to the empty vector group and control group. The apoptosis rate was significantly higher in PcDNA3.1/Smac + Taxol group than in other groups (p<0.05). Conclusions: Transfected Smac can enhance the chemosensitivity of the non-small cell lung cancer cell line A549 to Taxol.