ACCELERATED COMMUNICATION Inhibition of Bcl-XL Phosphorylation by Tea Polyphenols or Epigallocatechin-3-Gallate Is Associated with Prostate Cancer

Prostate cancer cells demonstrate slow growth kinetics and chemoresistance. Tea polyphenols have been shown to exert prostate cancer-preventative effects. Here we report that growth-arrested prostate cancer cells expressed high levels of a hyperphosphorylated Bcl-XL in mitochondria. Treatment with tea polyphenols or the major tea component epigallocatechin-3-gallate blocked expression of the hyper-, but not hypophos-phorylated Bcl-XL in mitochondria, accompanied by cyto-chrome c release, caspase activation, and apoptosis. Studies using specific inhibitors suggest that tea inhibits p38 mitogen-activated protein kinase and the proteasome activities, leading to inhibition of Bcl-XL phosphorylation and induction of pros-tate cancer cell death. Epidemiological and animal studies have demonstrated the cancer preventative properties of green tea polyphenol