Experimental Study On The Effects Of Quercetin On The Cell Cycle Of QGY And HepG2 Cell Lines

Objective To study the effects of quercetin on cell cycle and proliferation of QGY and HepG2 cell lines and the mechanism in vitro. Methods QGY and HepG2 cells were treated with a different concentration of quercetin. The inhibitory effect of quercetin on cell growth was observed by MTT-assay. Morphologic changes were studied under Electron Microscopy (EM). Flow cytometry (FC) was used to assay cell-DNA distribution and apoptosis. The expressions of CyclinA, CyclinB1, CyclinD1, P21WAF1, PCNA, Bcl-2 and Bax were detected by immunocytochemical method.Result After the treatment of quercetin on both QGY and HepG2, the cell growth was inhibited and cell cycle progression was delayed at G0/G1 phase in a time and dose dependent fashion,while the inhibitory effect was much stronger on HepG2 than that on QGY.Apoptosis was confirmed by the appearance of apoptotic peak on FC, characteristicultrastructural changes on EM. After treatment the expression of positive regulation factor PCNA and CyclinB1 were decreased in both cell lines, but the expression of cell cycle negative regulation factor P21WAF1 and apoptotic Bax were increased only in HepG2. Conclusion Quercetin suppressed the proliferation of QGY and HepG2 cell lines and increased population of the G0/G1 phase cell. The effect is related to the down-regulation of PCNA and/or up-regulation of P21WAF1. It also induced the apoptosis though the up-regulation of Bax in HepG2 cell line.