(-)-Epigallocatechin gallate induced apoptosis in human adrenal cancer NCI-H295 cells through caspase-dependent and caspase-independent pathway.

(-)-Epigallocatechin-3-gallate (EGCG) is a major constituent of green tea and has been identified as an excellent anticancer agent. Nevertheless, there are no reports to date about the molecular mechanisms and signal pathways of EGCG on the induction of apoptosis in human adrenal NCI-H295 cancer cells. The purpose of this study was to investigate the anticancer effect and molecular mechanisms of EGCG on human adrenal NCI-H295 cancer cells. The results showed that EGCG induced growth inhibition in a dose- and time-dependent manner. Moreover, it exerted low cytotoxicity on Detroit 551 normal human embryonic skin cell. When NCI-H295 cells were treated with 20 microM EGCG, the mitochondrial membrane potential decreased and intracellular free Ca(2+) increased in a time-dependent manner as analysed by flow cytometry. EGCG decreased the protein levels of Bcl-2, Bcl-xl, xIAP, cIAP, Hsp70 and Hsp90, but increased the protein expression of Bad, Bax, Fas/CD95, cytochrome c, Apaf-1, AIF, GADD153, GRP78, and caspase-3, -7,-8 and -9 as observed by Western blotting examination. EGCG promoted caspase-8, -9 and -3 activities in a time-dependent manner. However, pretreatment of cells with inhibitors of caspase-8, -9 and -3 led to a decrease in caspase-8, -9 and -3 activities and an increase in the percentage of viable cells. Based on the above findings, it was confirmed that EGCG may be a drug candidate for the treatment of human adrenal cancer in the future.