Inhibitory effect of epigallocatechin-3-gallate on growth and invasion in human biliary tract Carcinoma cells

Based on recent evidence that tea consumption contributes to a decreased incidence of human carcinomas, a number of investigators have focused on the mechanisms of cancer prevention by tea extracts, especially green tea polyphenols. Epigallocatechin-3-galIate (EGCG) is a representative polyphenol that inhibits the activity of the cyclin-dependent kinases of cdk2 and cdk4. This suggests that EGCG may exert its growth-inhibitory effects through modulation of G1 regulatory proteins such as cdk2 and cdk4. The human biliary tract carcinoma cells (TGBC-2, SK-ChA-1, and NOZC-1) were treated with different doses of EGCG (0, 25, 50, 100, and 200 µM) for 48 hours in cell medium. Cell proliferation was analyzed by WST-1 colorimetric assay. For the cell-invasion analysis, the cells were incubated with 100 µM of EGCG for 2 hours. The cells were then added into a Matrigel-coated Cell Insert. After incubation at 37°C for 24 hours, the cells visible through the Matrigel were counted under the microscope. All human biliary tract cancer cells studied showed a significant suppression of cell growth by EGCG treatment in a dose-dependent manner (27.2%, 16.0%, and 10.1%, in TGBC-2, SK-ChA-1, and NOZC-1, respectively, at the dose of 200 µM). EpigaIlocatechin-3-gallate treatment also produced a significant suppression of invasive ability of the carcinoma cells (12.6%, 11.2%, 7.9%, in TGBC-2, SK-ChA-1, and NOZC-1, respectively, at a dose of 100 µM). These data indicated that EGCG might be a potent biological inhibitor of human biliary tract cancers, reducing their proliferative and invasive activities.