Polyphyllin I (PPI) increased the sensitivity of hepatocellular carcinoma HepG2 cells to chemotherapy

In this study the antitumor effects of polyphyllin I (PPI) were investigated in hepatocellular carcinoma HepG2 cells. Our data showed that PPI treatment exerted dose-dependent cytotoxicity on HepG2 cells as previously reported. Furthermore, PPI could sensitize HepG2 cells to cisplastin treatment in concentration-dependent manner. The molecular mechanisms of PPI actions involved nuclear factor-κB (NF-κB) and its downstream gene products. PPI treatment dose-dependently could decrease the constitutive phosphorylation of NF-κB subunit p65 protein and its downstream target genes expression, such as Bcl-2, c-Myc and VEGF. PPI could also inhibit cisplatin-evoked increase of p65 protein phosphorylation and its downstream genes expression, which could be further decreased by combination with NF-κB specific inhibitor, PDTC. The cytotoxicity and chemosensitization effects of PPI on HepG2 cells were greatly potentiated by concomitant treatment with PDTC. Taken together, our data confirmed the cytotoxicity of PPI on hepatocellular carcinoma HepG2 cells and provided new findings about PPI sensitizing HepG2 cells to chemotherapy. Moreover, our data also indicated the involvement of NF-κB signaling pathway in PPIactions for the first time.