Investigation of the Effect of (-)-Epigallocathechin-3 Gallate on Apoptosis in HCT-116 Colon Cancer Cell Line

Objectives Epidemiologic studies which have been done until today have shown that the consumption of green tea lowers the risk of developing colon cancer. The anticancer effects of green tea have been attributed to the biological activities of its polyphenol components, catechins. The major catechin in green tea, (-)-epigallocatechin-3-gallate (EGCG), exhibits growth inhibitory activities against carcinogenesis in various cancer cell lines. Furthermore it has been shown that EGCG induces cell cycle arrest, apoptosis or necrosis depending on the concentration and incubation time used. However there are few studies focused on the effect of EGCG on colon cancer cell lines and the type of this effect has not been determined completely. In this study we aimed to observe antiproliferative effects of EGCG on HCT-116 colon cancer cells and on CCD18co normal colon cells, to determine the type of the cell death (apoptosis/necrosis) induced by EGCG and to determine the effect of EGCG treatment to the cell cycle.Materilals and Methods: To determine antiproliferative effects of EGCG on HCT-116 and CCD18co cell lines, MTT cell viability assay was carried out. The type of cell death induced in HCT-116 cells with EGCG was determined by flow cytometry, using Annexin/PI dyes and Cell Death Detection ELISAPLUS apoptosis assay. The effect of EGCG on cell cycle was determined by flow cytometric cell cycle regulation assay.Results and Conclusion:Data obtained indicated that EGCG induced cell death in a time and concentration depended manner in HCT-116 cells but not at concentrations less than 50uM. 50 and 100uM concentrations of EGCG caused 43% to 72% cell death but these concentrations did not induce cell death in CCD19co cells. Our results on cell death type analysis showed that apoptotic cell death ratio was 23% and 42% in HCT-116 cells treated with 50 and 100uM EGCG, respectively. Our results also indicated that neither necrosis nor cell cycle arrest was the main type of effect induced in cells.