Narrow Results

Anticarcinogenic effects attributed to phytochemicals may be based on synergistic, additive, or antagonistic interactions of many compounds. In our previous study, we demonstrated that the chloroform fraction (CHCl₃-F) from Z. jujuba has anticancer activity in HepG2 cells. In China, many people drink jujuba tea and believe in the synergic effects of jujuba and tea for better health. We therefore investigated the effects of CHCl₃-F and green tea extract (GTE), and their underlying mechanisms of action in HepG2 cells. Our results showed that GTE enhanced the effect of CHCl₃-F on cell viability in HepG2 cells, without cytotoxicity in rat hepatocytes, which was used as a normal cell model. Furthermore, combination of CHCl₃-F and GTE caused an effect on G1 phase arrest but not on apoptosis. Interestingly, the mechanism of the G1 arrest was associated, not with an increase in p27^Kip1 levels and the hypohosphorylation of Rb, which are pathways used by CHCl³-F on G1 arrest in HepG2 cells, but with increases in p53 and p21^Waf1/Cip1 levels, and a decrease in cyclin E levels. Collectively, our findings suggest that combination of CHCl₃-F and GTE produces an enhanced cell growth inhibition effect, and that the resultant G1 arrest was caused via a different mechanism as that of CHCl₃-F treatment alone.

Hepatocellular carcinoma is a type of tumor highly resistant to available chemotherapeutic agents. The treatment of hepatocellular carcinoma remains a challenge that needs new approaches in the future. In a previous study, we demonstrated that the chloroform fraction (CHCl₃-F) from Z. jujuba has anticancer activity in human liver cancer cells (HepG2), and that combining CHCl₃-F with green tea extracts (GTE) results in enhanced effects of anticancer activity in the cells. To further understand the mechanism of the anticancer activity of combining CHCl₃-F and GTE in HepG2 cells, we investigated whether the addition of a mixture of CHCl₃-F and GTE would affect the expression of APRIL (a proliferation-inducing ligand), which was expressed in HepG2 cells from 4 hours of incubation in vitro. We have shown that CHCl₃-F and GTE enhanced anti-cancer activity by reducing the expression of APRIL. We speculate that the CHCl₃-F and GTE mixture might provide a lead to a new drug design to treat hepatocellular carcinoma in the future.