20(S)-Protopanaxadiol induces apoptosis in human hepatoblastoma HepG2 cells by downregulating the protein kinase B signaling pathway

Hepatoblastoma is the most common primary liver tumor for children aged <5 years old. 20(S)-Protopanaxadiol (PPD) is a ginsenoside extracted from Pananx quinquefolium L., which inhibits tumor growth in several cancer cell lines. The purpose of the present study was to assess the anticancer activities of 20(S)-PPD in human hepatoblastoma HepG2 cells. The cytotoxicity of 20(S)-PPD on HepG2 cells was evaluated using an MTT assay. Apoptosis was detected using DAPI staining and flow cytometry. The expression of apoptosis-associated proteins was identified by western blotting. The results demonstrated that 20(S)-PPD inhibited the viability of HepG2 cell in a dose and time-dependent manner. The IC50 values were 81.35, 73.5, 48.79 mu M at 24, 48 and 72 h, respectively. Topical morphological changes of apoptotic body formation following 20(S)-PPD treatment were detected by DAPI staining. The percentage of Annexin V-fluoroscein isothyiocyanate positive cells were 3.73, 17.61, 23.44 and 65.43% in HepG2 cells treated with 0, 40, 50 and 60 mu M of 20(S)-PPD, respectively. Furthermore, 20(S)-PPD upregulated the expression of Bax and downregulated the expression of Bcl-2 and also activated caspases-3 and -9, and Poly [ADP-ribose] polymerase cleavage. In addition, 20(S)-PPD inhibited the phosphorylation of protein kinase B (Akt; Ser473). The results indicate that 20(S)-PPD inhibits the viability of HepG2 cells and induces apoptosis in HepG2 cells by inhibiting the phosphoinositide-3-kinase/Akt pathway.