Apoptosis in HepaRG and HL-7702 cells inducted by polyphyllin II through caspases activation and cell-cycle arrest.

Rhizoma Paridis, a traditional Chinese medicine, has shown promise in cancer prevention and therapy. Polyphyllin II is one of the most significant saponins in Rhizoma Paridis and it has toxic effects on kinds of cancer cells. However, our results in this study proved that the polyphyllin II has hepatotoxicity in vitro through caspases activation and cell-cycle arrest. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide results indicated polyphyllin II inhibited proliferation, induced apoptosis in HepaRG cells and HL-7702 cells and showed a concentration and time-dependent. Then, we selected the innovative cell model-HepaRG cells to explore the mechanism of hepatotoxicity. Our data showed the reactive oxygen species (ROS) increased and the mitochondrial membrane potential decreased in HepaRG cells after administration of polyphyllin II. Besides, with the increase of concentration, the release of lactate dehydrogenase increased and the S phase of the cell cycle was arrested. Nevertheless, when pretreatment with antioxidant N-acetylcysteine, apoptotic cells decreased significantly, inhibited the production of ROS and improved the decrease of membrane potential in HepaRG cells. Moreover, polyphyllin II treatment increased levels of Fas, Bax, cytochrome c, activated caspase-3, -8, -9, cleaved poly(ADP-ribose) polymerase and decreased Bcl-2 expression levels. Finally, we identified two signal pathways of apoptosis induced by polyphyllin II including the death receptor pathway and the mitochondria pathway. This study confirmed the hepatotoxicity of the polyphyllin II in vitro, which has never been discovered and gave a wake-up call for the clinical application of Rhizoma Paridis.