Effects of epigallocatechin-3-gallate on the differential expression of apoptosis-associated genes in human gastric cancer MGC-803 cells / 中国肿瘤临床

ABSTRACT

Objective: This study investigates the biological effects and explores the molecular mechanisms of epigallocate-chin-3-gallate (EGCG) on the apoptosis of the human gastric cancer MGC-803 cells. Methods: After treatment with EGCG, cell apopto-sis was verified by flow cytometry with Annexin V and propidium iodide staining, DNA agarose gel electrophoresis, and transmission electron microscopy. The expression profiles of the apoptosis-related genes in the MGC-803 cells with or without treatment by EGCG for 12 h (100 μmol/L), was identified using SuperArray Human Apoptosis Gene Array. The upregulated Fas-L gene and down-regulated Bag-1 gene were confirmed by reverse transcription polymerase chain reaction (RT-PCR) and Western blot. Results: When the MGC-803 cells were treated with EGCG at 25, 50, 100, and 200 μmol/L for 24 h, evident sub-diploid peaks were observed. Under treat-ment with 100 μmol/L for 4, 8, 12, and 24 h, the number of early apoptotic cells was greatly increased. When the cells were treated with 100 μmol/L for 24 h, the DNA extracted from the cells displayed a characteristic ladder pattern with agarose gel electrophoresis. Typi-cal morphological changes were observed by electron microscopy, including cell shrinkage, karyo-pyknosis, and the formation of apop-totic bodies. The differential expressions of eight apoptosis-associated genes were determined by gene array detection. The results of Fas-L and Bag-1 selected for RT-PCR and Western blot were consistent with those of gene array. Conclusion: EGCG induces apoptosis in MGC-803 cells, which might be mediated by a number of specific genes and various signal transduction pathways.