Methyl protodioscin induces G2/M cell cycle arrest and apoptosis in A549 human lung cancer cells

Background: Methyl protodioscin (MPD) is a furostanol bisglycoside with antitumor properties. It has been shown to reduce proliferation, cause cell cycle arrest.

Objective: The present study elucidates the mechanism underlying MPD's apoptotic effects, using the A549 human lung Cancer cell line.

Materials and methods: The human pulmonary adenocarcinoma cell line A549 was obtained from the Cell Bank of the Animal Experiment Center, North School Region, Sun Yat-Sen University. All of the cells were grown in RPMI 1640 supplemented with 10% fetal calf serum (Hyclone, Logan, UT, USA), penicillin (10,000 U/l), and streptomycin (100 mg/l) at 37°C in a 5% CO2 humidified atmosphere. The induction of Apoptosis was observed in flow cytometry and fluorescent staining experiments.

Results: MPD showed growth inhibitory effects in A549 cells in a dose- and time-dependent manner. The significant G2/M cell cycle arrest and apoptotic effect were also seen in A549 cells treated with MPD. MPD-induced Apoptosis was accompanied by a significant reduction of mitochondrial membrane potential, release of mitochondrial cytochrome c to cytosol, activation of Caspase-3, downregulation of Bcl-2, p-Bad, and upregulation of Bax.

Conclusion: Our results show that the induction of Apoptosis by MPD involves multiple molecular pathways and strongly suggest that Bcl-2 Family proteins signaling pathways. In addition, mitochondrial membrane potential, mitochondrial cytochrome c and Caspase-3 were also closely associated with MPD-induced apoptotic process in human A549 cells.