Steroidal Saponins from Paris polyphylla Induce Apoptotic Cell Death and Autophagy in A549 Human Lung Cancer Cells

BACKGROUND: Paris polyphylla (Chinese name: Chonglou) had been traditionally used for a long time and shown anti-cancer action. Based on the previous study that paris polyphylla steroidal saponins (PPSS) induced cytotoxic effect in human lung cancer A549 cells, this study was designed to further illustrate the mechanisms underlying. MATERIALS AND METHODS: The mechanisms involved in PPSS-induced A549 cell death were investigated by phase contrast microscopy and fluorescence microscopy, flow cytometry and western blot analysis, respectively. RESULTS: PPSS decreased the proportion of viable A549 cells, and exposure of A549 cells to PPSS led to both apoptosis and autophagy. Apoptosis was due to activations of caspase-8, caspase-3, as well as cleavage of PARP, and autophagy was confirmed by up-regulation of Beclin 1 and the conversion from LC3 I to LC3 II. CONCLUSIONS: PPSS was able to induce lung cancer A549 cell apoptosis and autophagy in vitro, the results underlining the possibility that PPSS would be a potential candidate for intervention against lung cancer.