Experimental Study On The Effect Of Resveratrol On Cell Cycle Of HepG2 Cells

【Background and objective】Resveratrol(3,5,4-trihydroxystilbene,the trans-isoform) is a natural polyphenolic compound occurring in various plants and is also found in high concentrations in one of the end products of grapes,red wine,has been reported to posses a potential function including anti-inflammatory,anti-oxygen,anti-tumor, protection of heart-blood vessel and suppression of platelet aggregation.Researches showed that resveratrol have cancer chemopreventive activity in vivo and in vitro, and its cancer chemopreventive mechanism involves prevention,delay,or reversal of the process of tumor initiation,promotion and progression,three major stages of carcinogenesis.Blocking the cell cycles through different stage of tumor cells is one of the most important mechanisms by which resveratrol exerts its anticarcinogenic effects.Cell cycle has been defined as the interval between the completion of mitosis in a cell and the completion of mitosis by one or both of its daughter cells.Traditionally the cell cycle has been divided into four phases:Gap phase 1(G1);DNA synthesis (S);Gap phase 2(G2),during which the cell prepares itself for division;and mitosis (M) during which the chromosomes separate and the cell divides.The progression of cell cycle from one phase to the next is regulated by sequential activation and inactivation of many products of cell division cycle(cdc) gene including cyclin and cyclin dependent kinase(CDK).Cyclins control various phases of the cell cycle through their ability to form a complex with a CDK partner.Cyclin E/CDK2 not only play a pivotal role in the regulation of G1-S transition but also in the initiation of DNA replication and relates to malignant transformation of the cells.Cyclin E overexpressions were observed frequently in deeply invasive tumors.Several reports indicate resveratrol inhibits proliferation of cancer cells by inhibiting cell cycle progression at different stages of the cell cycle was associated with a reduced level of expression of cyclins and CDKs,and enhanced levels of Cip1/p21 and Kip1/p27 proteins.In the current study,we investigated resveratrol-induced cell cycle arrest in human hepatoblastoma-derived HepG2 cell line and the potential mechanisms involving Cyclin E/CDK2 inactivation in order to further provide extensively experimental foundation for resveratrol study.【Methods】In the current study,the growth and proliferatrion of HepG2 cell were observed by the phasecontrast microscope.The effects of resveratrol on cell cycle and cdk2, cyclin E expression were measured by flow cytometry.Data are presented as mean±SE,multi-factor analysis of variance and one-way Anova were performed followed by LSD multiple comparisons test,Dunnet-t multiple comparisons test when heterogeneity of variance occured,using SPSS statistical software. 【Results】1.The effect of resvertrol on proliferation and apoptotic death in HepG2 cellsThe result of observation of morphology under microscopy shows that resveratrol(25,50,100μmol/L ) could obviously inhibit the proliferation of HepG2 cells.In addition,resveratrol could induce cell apoptosis.2.The effect of resveratrol on HepG2 cell cycleThe result of flow cytometry showed that resveratrol(25,50,100μmol/L) cause an increase of cells in the S phase and a corresponding decrease of cells in the G0/G1 compared to control group.It indicated that resveratrol showed cell cycle arrested in S-phase.3.The effect of resveratrol on CDK2,cyclin E protein expression.The result of flow cytometry showed that resveratrol(25,50,100μmol/L) cause enhanced levels of CDK2 and cyclin E proteins compare to control in a dose-dependent manner.【Conclusion】Resveratrol strongly inhibit the proliferatrion of HepG2 cells,induced apoptosis and cell cycle arrest at S-phase.