Jpn J Clin OncoI1998;28(6)360-363, Original Articles I Effects of Soybean Isoflavones on Cell Growth and Apoptosis of

Background: Epidemiological studieshave suggested that soybean isoflavones are associated with a lower riskof prostate cancer. However, the mechanisms of prostate cancerprevention by soybean isoflavones haveyet to be fully clarified. Methods: Two soybean isoflavones (genistein and daidzein) and their glucosides (genistin and daidzin) were tested for theireffects on cell growthand apoptosis of the LNCaP humanprostatic cancer cell line. Results: Among these isoflavones, genistein was found to inhibit the growth of LNCaP most effectively, withan ICsovalue of 40 J.lM. The inhibition of cellgrowth by genistein wasaccompanied by thesuppression ofDNAsynthesis andthe induction ofapoptosis. Expression ofprostate-specific antigen (PSA) in LNCaP was also significantly reduced by the treatment with genistein. Conclusions: Theresults suggest thatgenistein mightprimarily influence human prostatecancer development by reducing tumorgrowth. Key words: genistein- isoflavone- soybean- prostatecance