EGCG Inhibit Cell Proliferation Of Hela Cells Via The Downstream Factors Of MTOR Pathway:S6K1and4E-BP1

The mammalian target of rapamycin (mTOR) is a serine/threonine protein kinase that is centrally involved in the control of cell growth, proliferation, differentiation and cell cycle regulation. Recent studies have found that the mTOR pathway is complicated and is recognized to be associated with lots of tumors functions. So far the4E-BP1(eukaryotic translation initiation factor4E binding protein1) and S6K1(Ribosomal protein S6kinase beta-1) were the most popular substrates of mTOR. EGCG (Epigallocatechin-3-gallate) is the main functional component from tea, and has the vital significance to human health and longevity with its natural character.This study aimed to investigate the in vitro inhibition of proliferation of cervical carcinoma HeLa cells treated by EGCG (The concentration of EGCG treatment was0μM,10μM,25μM,50μM and100μM) and reveal the mechanism of drinking tea, which may lay a theoretical foundation to development and utilization of medicine-use of tea. The study was conducted by morphologic observation of HeLa cells, and CellTiter-Blue method was used to observe the cells proliferation lines, Flow Cytometry (FCM) method was used to investigate the cell cycle of HeLa cells, western-blotting method was used to detect the phosphorylation of S6K1and4E-BP1.The results show that under low-serum (0.5%FBS) conditions, EGCG has dose-dependent inhibition effect on the proliferation of HeLa cells. Meanwhile, an increase in the proportion of cells in S phase and an obvious accumulation of cells in G2/M phase in a dose-dependent manner was observed in EGCG-treated HeLa cells, which indicated that EGCG-treatment could result in cell cycle arrest in S and G2/M phase. What’s more, the phosphorylation levels of4E-BP1protein in HeLa cells showed a significant decrease in an EGCG dose-dependent manner. However, under high-serum (10%FBS) conditions, such inhibition of cell proliferation was showed lightly in HeLa cells, only at the high concentration of EGCG (50μM and100μM) was observed some kind of inhibition. The cell cycle of HeLa cells were delayed in S, G2/M phase and the phosphorylation levels of S6K1protein in HeLa cells decreased significantly after100μM EGCG treatment. Whereas the phosphorylation levels of4E-BP1protein in HeLa cells showed no significant decreasing when treated by different concentration of EGCG.Therefore, EGCG treatment has a certain inhibitory effect on the proliferation of HeLa cells, especially under low-serum conditions. In conclusion, our results show that4E-BP1is likely to be the target of EGCG which inhibited proliferation of HeLa cells via the mTOR pathway, and we supposed that if we could control the level of energy during the treatment of EGCG, the function of EGCG would likely be more effectively. More research would be done.