OBJECTIVETo investigate the biological behaviors and chemosensitivity of non-small cell lung cancer (NSCLC) cell line A549 after IGF-IR gene silencing by RNA interference (RNAi) in vitro.

METHODSTwo plasmids siRNA 1 and 2 expressing IGF-IR siRNA with human U6 promoter were constructed,and an unrelated siRNA was used as negative control. NSCLC A549 cells were transfected with sequence-specific siRNA or unrelated siRNA as control. Quantitative RT-PCR and Western blot were used to detect the expression of IGF-IR. NSCLC A549 cells were transfected with siRNA and treated with DDP. MTT assay and flow cytometry were used to assess the effects of IGF-IR silencing on tumor cell proliferation and chemosensitivity.

RESULTTransfection of NSCLC cells with siRNA resulted in reduction of IGF-IR mRNA expression by 78.9 % and protein production by 89.8%. The decrease in IGF-IR levels caused significant growth inhibition of A549 cells both at 48 h and at 72 h, and decrease of the IC50 of DDP at 24 h, 48 h and at 72 h. Flow cytometry showed that 77.5% of A549 cells retained in G0/G1 phase.

CONCLUSIONThe sequence specific suppression of IGF-IR gene expression by RNAi enhances sensitivity to DDP in NSCLC cell.