Caudatin induces cell cycle arrest and caspase-dependent apoptosis in HepG2 cell

In the present study, we investigate the anti-cancer activity and mechanism of caudatin, the C-21 steroidal glycosides, on human hepatoma cell line HepG2. The MTT assay and flow cytometry were used to evaluate HepG2 cell proliferation and cell cycle. Annexin-V/PI and DAPI staining were used to investigate cell apoptosis. Western blotting analysis was used to evaluate the expression levels of proteins. It is found that caudatin inhibits HepG2 cell growth and induces of G(0)/G(1) phase arrest in a dose dependent manner, which is associated with a decreased in the expression of cyclinD(1) and increased the levels of p21 and p53. HepG2 cells dealing with caudatin showed typical characteristics of apoptosis. Western blotting analysis indicated that the levels of Bcl-2 were down-regulated after caudatin treatment, whereas the expression of Bax was up-regulated. Furthermore, caudatin-induced apoptosis was accompanied by activation of caspase-3, -9, and poly(ADP-Ribose) Polymerase (PARP). Treatment with caudatin also induced phosphorylation of extracellular-signal regulating kinase (ERK) and c-Jun N-terminal kinase (JNK). These results demonstrate that caudatin inhibits cell proliferation via DNA synthesis reduction and induces caspase-dependent apoptosis in HepG2 cell. Activation of ERK and JNK may be involved in caudatin-induced hepatoma cell apoptosis.