Role of Zn2+ in epigallocatechin gallate affecting the growth of PC-3 cells

Green tea has chemo-preventive effects to human carcinoma including prostate cancer. Epigallocatechin gallate (EGCG) is the major active component in green tea. Zn2+ is indispensable to our health, and plays an important role in the normal function and pathology of the prostate gland, and might be a good marker for diagnosing prostate cancer. Effects of Zn2+, EGCG and their interactions on the growth of androgen-insensitive prostate cancer cell (PC-3) were investigated in the present paper. The results show that Zn2+ and EGCG inhibited the growth of PC-3 cells in a time- and dose-dependent manner, but effects of interactions of EGCG with Zn2+ were extremely dependent on their concentrations and added orders. Inhibitory effects of Zn2+ were significantly decreased in the presence of EGCG on PC-3 cell growth. Therefore, we hypothesize that complexation of EGCG with Zn2+ might be responsible for the observed decrease of the bioactivities of Zn2+ against PC-3 cells.