Molecular Mechanism Of Growth Inhibition Of Human Hepatocellucar Carcinoma Cell Line HepG2 With Genistein And Daidzein

Primary hepatic carcinoma (PHC) is a kind of malignancies worldwide of morbidity and mortality.Up to now,surgical resection is still the main route but usually unsatisfied because hepatoma often accompanies by cirrhosis and early metastasis in liver. Chemotherapy is also unsatisfied because of its toxicity and side effects. Therefore, the current study focuses on finding noncelltoxical drugs which can suppress human hepatoma and improve the life quality of patients.Genistein and Daidzein are essential components of soy isoflavone which have similar structures,and they both have extensive biological function.Most studies focus on hormone-dependent neoplasms such as prostatic carcinoma and mastocarcinoma,few studies have addressed about their inhibition effect on human hepatoma cells,so we took human hepatoma cell line HepG2 as research object. MTT assay showed that Genistein and Daidzein both suppressed the proliferation of HepG2 cells in dose and time-dependent manner. Flow cytometry and detection of apoptosis proteins showed that Genistein and Daidzein both induced cell cycle arrest(Genistein induced G2-M phase arrest,and Daidzein induced G1-S phase arrest) and apoptosis regulated by Bcl-2 protein family. In order to explore molecular mechanism of their growth inhibition,we studied through analysis of effects of Genistein and Daidzein on DNA damage and telomerase activity regulation signal pathway.As the bio-molecular foundation of chemoradiotherapy of antitumous effect,DNA damages induce cell cycle arrest and apoptosis via checkpoint system. SCGE,western blot and analysis associated with Caffeine showed that Genistein and Daidzein both induced DNA damage and activated several DNA damage proteins. Genistein may induce G2-M phase arrest though ATM-Chk2-Cdc25C-Cdc2 pathway,while the mechanism of G1-S phase arrest induced by Daidzein is still unclear.We also valued the effects of Genistein and Daidzein on telomerase activity.Telomerase activation is a key tumor marker which immortalizes cell.If a medicine blocks telomere prolonging by attenuation of telomerase activity, it could inhibit tumor cells proliferation. TRAP silver-staining analysis showed that HepG2 cell telomerase activity were decreased by treatment of Genistein and Daidzein.On one hand, they both inhibit expression of c-myc and hTERT.On the other hand, active modifyication of hTERT are blocked by their inhibition of phosphorylation of Akt.In summary,Genistein and Daidzein both inhibit HepG2 cell proliferatation by inducing DNA damage and decreasing of telomerase activity,so they are both potential antitumous medicines in the future.