The Inhibitory Effects Of EGCG On Proliferation Of Human Gastric Cancer MGC-803 Cells Via Induction Of Cell Cycle G₁ Phase Arrest And Its Molecular Mechanism

Objective: To investigate the effects of green tea extract epigallocatechin-3-gallate (EGCG) on proliferation of human gastric cancer cell line MGC-803 and its molecular mechanism.Methods: MGC-803 cells were cultured in vitro.MTT assay was used to test the inhibitory effects of EGCG on proliferation in MGC-803 cells.The change of cell cycle in MGC-803 cells treated with EGCG for various dose and for various time periods was analyzed using flow cytometry.The expression of p21^WAF1, p53, Cyclin E, c-Myc proteins were detected by immunocytochemistry.The phosphorylated and total protein levels of Erk1/2 and Rb were examined using western blot.Results :MTT assay has shown that EGCG significantly inhibited proliferation of MGC-803 cells in a concentration dependent manner. After treatment with EGCG(20ug/mL,40ug/mL, 60ug/mL, 80ug/mL,100ug/mL) for 48 h, MGC-803 cells growth inhibit rates were 21.7%, 32.8%, 52.5%, 61.3%, 66.5%.IC₅₀=58.60μg/mL.Flow cytometry analysis revealed that EGCG induce human gastric cancer cell MGC-803 G1 phase arrest. In various time groups, the proportion of cells in G1 phase after treatment with EGCG were increased compared with untreated groups.Immunocytochemical stain detected the expression downregulation of p53, Cyclin E, c-Myc proteins in MGC-803 cells after incubated with EGCG (60ug/mL) for 48 h,while p21^WAF1 protein upregulation.Western blot confirmed EGCG effectively downregulated phosphor-Erk1/2 and phosphor-Rb prorein levels,while total Erkl/2 and Rb protein levels were not affected.