Growth inhibition of prostate cancer cells by epigallocatechin gallate in the presence of Cu2+

Green tea is an effective chemopreventive agent to human prostate cancer adenoma (PCA). Epigallocatechin gallate (EGCG) inhibited the growth of PCA cells and induced apoptosis. Cu(2+) is a trace element necessary to our health. Many studies proved that bioactivity of EGCG is altered in the presence of Cu(2+). We investigated the effects of EGCG on PCA cells in the presence of Cu(2+). Also, we explored potential mechanisms via measurement of the relative chemiluminescence of growth medium for PCA cells. Chemiluminscence can be an indication of free radicals. Our test results showed that the addition of EGCG and Cu(2+) to the growth medium decreased the relative viability of androgen-sensitive and androgen-insensitive human prostate cancer cells. However, the effects of EGCG on PCA cells depended on (1) the relative concentrations of added EGCG and Cu(2+) and (2) their order of addition. Our results indicated that few free radicals may be generated in vitro. If so, free radicals generated intracellularly may be a major factor behind apoptosis and growth inhibition observed in the PCA cells. Thus, EGCG might exert its effects intracellularly.