Abstract: Objective: To explore the inhibitory effects of cardiac glycosides(Digoxin，Gitoxin, Digitoxin) on human lung cancer cell lines A549 and H1975.Methods: After treated by Gitoxin,Digitoxin and Digoxin ,the drug sensitivity of human lung cancer cells (A549 and H1975) to cardiac glycosides were detected by MTS assay. The change of cell apoptosis and proliferation were analyzed by using flow cytometry. Results: A549 and H1975 were exposed to cardiac glycosides for 48h at different concentrations. H1975 with a 50% inhibiting concentration of about 100nM was more sensitive to A549 with a 50% inhibiting concentration above 10μM. Flow cytometry demonstrated that cardiac glycosides could induce apoptosis to A549 and H1975.And the apoptosis rate of H1975 showed dose-depended manner. Also, the cardiac glycosides could inhibit the proliferation of both cell lines at different concentrations. Conclusions：Cardiac glycosides could induce apoptosis and inhibit proliferation of A549 and H1975.But it showed great differences for the different genetics background of them.

Key words: Cardiac glycosides, Lung cancer cell, Cell apoptosis, Cell proliferation