Paris saponin VII induces cell cycle arrest and apoptosis by regulating Akt/MAPK pathway and inhibition of P-glycoprotein in K562/ADR cells.

Paris saponinVII (PSVII) is a steroidal saponin isolated from the roots and rhizomes of Trillium tschonoskii Maxim. We found that PSVII could inhibit the growth of adriamycin-resistant human leukemia cells (K562/ADR) in a dose-dependent manner. Furthermore, the molecular mechanism underlying the cytotoxicity and downregulation of P-glycoprotein (P-gp) expression by PSVII was clarified. PSVII significantly suppressed cell proliferation by cell cycle arrest in the G0/G1 phase, which was associated with an obvious decrease in cyclin B1/D1 and CDK2/4/6 protein expression. Moreover, PSVII could attenuate mitochondrial membrane potential, increase the expression of apoptosis-related proteins, such as Bax and cytochrome c, and decrease the protein expression levels of Bcl-2, caspase-9, caspase-3, PARP-1, and p-Akt. We also found that JNK, ERK1/2, and p38 were regulated by PSVII in K562/ADR cells. And further studies indicated that the decrease in the reactive oxygen species level inhibited intrinsic P-gp expression. Therefore, PSVII-induced apoptosis in K562/ADR cells was associated with Akt/MAPK and the inhibition of P-gp. In addition, PSVII induced a robust autophagy in K562/ADR cells as demonstrated by the degradation of LC3-I. These results provide a biochemical basis for possible clinical applications of PSVII in the treatment of leukemia.