Objective To investigate the effects of Kanglaite injection（KLT）combined with gefitinib on the lung adenocarcinoma A549 cell proliferation and apoptosis in vitro. Methods MTT assay was applied to calculate the half inhibitory concerntration（IC50） of KLT acting on human lung adenocarcinoma A549 cells for 48 h，and detect the inhibition rates by treating A549 cells with KLT（5，10，20，40，80，100，160 μl／ml），gefitinib（0.1，0.5，1.0，5，10，20，40 μmol／L） and KLT（80 μl／ml） combined with different doses of gefitinib for 24，48，72 h. Flow cytometry（FCM） was employed to detect the cell apoptosis for 48 h. Immunocytochemical and RT-PCR methods were used to detect the protien and mRNA express of AKT2 and FAS，respectively. Cells without drug was set as blank control group.

ResultsMTT assay showed that IC50 of KLT acting on A549 cells for 48 h was 80 μl／ml. Compared with both single drug groups and control group， KLT combined with gefitinib could significantly inhibit the proliferation of A549 cells in a time-and dose-dependent manner. FCM showed that the cell apoptotic rates of combined group higher than those of both single drug groups and control group（P＜0.05）. Immunocytochemical and RT-PCR detection showed that compared with the control group， the FAS protein and mRNA levels of the KLT in combined group were increased， but AKT2 decreased（P＜0.05）. Conclusion The combination of KLT and gefitinib can induce cell apoptosis significantly. KLT may increase the sensitivity of the human lung adenocarcinoma cell line A549 for gefitinib.