Apoptotic effect of epigallocatechin-3=gallate on the human gastric cancer cell line MKN45 via activation of the mitochondrial pathway

Abstract

Aim: To investigate whether Epigallocatechin-3-gallate (EGCG) can induce apoptosis of the gastric cancer cell line MKN45 and its apoptotic pathway. Methods: To determine this, apoptotic nates of MKN45 cells after EGCG treatment with or without caspase-3 inhibitor were evaluated by Annexin V-FITC + PI staining The influence of EGCG on the activity of caspase-3 in the MKN45 cells was determined by ELISA. By Rhodamine123 staining, the membrane potential change of the mitochondrion was also investigated, and mRNAs and protein expression of the bcl-2 family were analyzed by RT-PCR and Western blot. Results: EGCG can induce apoptosis of MKN45 cells in time- and dose-dependent manner. Eight hours after EGCG treatment, the activity of caspase-3 in the MKN45 increased, especially 12 h after treatment. The mitochondrial membrane potential was significantly weakened 4 h after EGCG insult. The mRNA and protein expression levels of pro-apoptotic members, such as Bax, Bid and Bad, were upregulated gradually as treated time increased. Moreover, the rnRNA and protein expression levels of anti-apoptotic members, such as Bcl-xL and Bcl-2, were inhibited. Conclusion: These data support that EGCG can induce apoptosis of the human gastric cancer cell line MKN45, and the effect is in a time- and dose-dependent manner. The apoptotic pathway triggered by EGCG in MKN45 is mitochondrial-dependent. © 2007 WJG. All rights reserved.