Effect Of Tea Polyphenols On Cell Cycle Of Human Liver Cancer Cell

Objective:In the present study, we have investigated the effect of tea polyphenols(TP) on the proliferation, changes of cell morphology, cell cycle , expression changes of CyclinDl of human liver cancer cell SMMC-7721, the dose-response relationship about effect of TP on SMMC-7721 cell was established.we have investigated the effect of TP on expression changes of CyclinDl, the effect of activator protein l(AP-l) and p16 on signal transduction pathways of CyclinDl was discussed, the possible molecular mechanisms about effect of tea polyphenols on SMMC-7721 cell was studied.Method:In the present study, we have investigated the effect of TP on human liver cancer cell SMMC-7721 in vitro, (1) Effect of TP on the proliferation of human liver cancer cell SMMC-7721 was determined by MTT assay, the dose-response relationship about effect of TP on SMMC-7721 cell was established. (2) Changes of human liver cancer cell morphology were studied through HE staining. (3) Effect of TP on the cell cycle of human liver cancer cell SMMC-7721 was analyzed by flow cytometry.For the possible molecular mechanisms about effect of tea polyphenols on SMMC-7721 cells, (1) we studied the expression changes of CyclinDland pi6 by the immunity cell chemistry method and analysis of gradation.(2) Activator protein 1 luciferase reporter gene was constructed and measured the activities of activator protein 1 ,at the same time, psv-|3-gal plasmid was transfected to correct transfection efficiency of reporter gene.Result:The survival rate of hman liver cancer SMCC-7721 decreased with the rise of TP concentration and for more time,there was a siginifcant difference in 25mg/L and 50mg/L concentration (proliferation was 94.12% and 80.08%, /=4.01 l,P<0.01) . We have investigated the apoptosis induced by TP, these changes included that cell turned round and shrinkaged,thromatin condensed in cells. We found that with increase of doses of TP,the number of cells in the s-phase was decreased from 60.4% ( Omg/L) to 23.9% ( lOOmg/L) ,and the number of cells in the Gi phase was increased from 31.6% (Omg/L ) to 63.6%( Omg/L)in 48 hour,suggesting that TP could arrest the cell cycle at Gi checkpoint.TP repressed activities of activator protein 1 and expression of CyclinDl,but expression of P16 was not changed.Conclusion:(1) The proliferation of human liver cancer cell was decreased by TP, the apoptosis induced by TP was observed. TP arrest cell cycle of human liver cancer cell at Gi checkpoint.There was a dose-response relationship about effect of TP on SMMC-7721 cell.(2) The possible molecular mechanisms about effect of TP on human liver cancer cell:TP could inhibit cell proliferation and arrest cell cycle at GI checkpoint by suppressing expression of CyclinDl. Suppressing the tansactivities of AP-1 and down-regulation the transcription of CyclinDl...