Effects of soybean isoflavones on cell growth and apoptosis of the human prostatic cancer cell line LNCaP

Background: Epidemiological studies have suggested that soybean isoflavones are associated with a lower risk of prostate cancer. However, the mechanisms of prostate cancer prevention by soybean isoflavones have yet to be fully clarified. Methods: Two soybean isoflavones (genistein and daidzein) and their glucosides (genistin and daidzin) were tested for their effects on cell growth and apoptosis of the LNCaP human prostatic cancer cell line. Results: Among these isoflavones, genistein was found to inhibit the growth of LNCaP most effectively, with an IC50 value of 40 mu M. The inhibition of cell growth by genistein was accompanied by the suppression of DNA synthesis and the induction of apoptosis. Expression of prostate-specific antigen (PSA) in LNCaP was also significantly reduced by the treatment with genistein. Conclusions: The results suggest that genistein might primarily influence human prostate cancer development by reducing tumor growth.