Abstract: Objective: To investigate the sensitivity of lung adenocarcinoma cells to gemcitabine(GE) after c-myc RNA interference.Methods: The c-myc-siRNA expression vector was constructed and confirmed by sequencing,and its expression vector was transfected into A549 cells.G418(geneticin) was used for selecting the cell line which expressed c-myc-siRNA stably.The level of c-myc was tested by FQ RT-PCR and western blot.The transfected cells were treated with gemcitabine,which were then divide into GE+siRNA group,GE group,siRNA group and control group,with 12 cases in each.The cell proliferation and apoptosis were assayed by tetrazolium bromide colorimetry and flow cyclometry,respectively.Results: c-myc-siRNA expression vector was constructed and transfected into A549 cells successfully.The c-myc mRNA and protein expression was effectively reduced(71.9% and 85.6% respectively).The cells treated with c-myc-siRNA and gemcitabine had a lower absorbance value at each time point than that of simple gemcitabine group,simple c-myc-siRNA group or control group(P<0.01),and the apoptosis rate was also decreased(P<0.01).Conclusions: The c-myc RNA interference can enhance the sensitivity of lung adenocarcinoma A549 cells to gemcitabine.