Synergistic effects of thearubigin and genistein on human prostate tumor cell (PC-3) growth via cell cycle arrest

There is evidence that habitual consumption of green tea by Japanese men is correlated with a reduction in cancers, including prostate; soybean isoflavones are also associated with increased protection. The present study compared the anti-proliferative effect of black tea (Camellia sinensis) polyphenol, thearubigin (TR), alone or combined with the isoflavone genistein, on human prostate (PC-3) carcinoma cells. TR administered alone did not result in any alteration of cell growth. When combined with genistein, however, TR significantly inhibited cell growth and induced a G2/M phase cell cycle arrest in a dose dependent manner. These findings indicate the potential use of combined phytochemicals to provide protection against prostate cancer. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.