Early Effect of (-)-epigallocatechin-3-gallate(EGCG) on Phosphorylation of Akt
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In t his study, we tried to identify the key elements that respond to EGCG t reatment and its role in cell survival 0 1' apop tosis by EGCG. focusing on Akt pathway and Raf-MEK-ERK pathways. Cells were serum starved for 16 h and then treated with (-) -epiga llocatechin-3-gallate. To cletermine which pathway is related to effects of EGCG on cell s, the levels of phosphorylated Akt(pAkt) and Erk (pErk) were a nalyzed by immunoblotting. A549 cell s showed the increase of pAkt in response to EGCG‘ whereas Hela cells exhi bited no difference in the levels of pAkt by EGCG treatment Phos phorylation of Akt over initial basal levels became evident a fter 1 h of EGCG treatment and peaked at 3 h pErk was also increased by EGCG in Hela cells as well as in A549 cells To determine th e effect of EGCG on growth of cells‘ A549 cells were treated wi th vari 。u s concentrations of EGCG (from 10 μ M to 300 μ M) for 3 h. Cell growth was examined by MTI assay. The resulting growth curves of A549 cell s showed that EGCG promotecl cell prolifera tion in a close-dependent manner at early phase. When cells were t rea ted with EGCG for 24 h. pAkt and pErk expressions were significantly i띠1ibited ， even at 10 μ M B-raf ex pression was also clecreased in a close-dependent manner. In teresti ngly. the presence of serum weakened t his inhibitory effect of EGCG on the ex pression of survival facto rs. Our study inrucates that EGCG stimulates cell survival of A549 cells through thc PI3K/AKT pathway. though it fina lly be haves like a suppressive agent on cell su rvival