title: p53-independent induction of p21 (WAF1/CIP1), reduction of cyclin B1 and G2/M arrest by the isoflavone genistein in human prostate carcinoma cells.
abstract: Genistein, a natural isoflavonoid phytoestrogen, is a strong inhibitor of protein tyrosine kinase and DNA topoisomerase II activities. Genistein has been shown to have anticancer proliferation, differentiation and chemopreventive effects. In the present study, we have addressed the mechanism of action by which genistein suppressed the proliferation of p53-null human prostate carcinoma cells. Genistein significantly inhibited the cell growth, which effect was reversible, and induced dendrite-like structure. The inhibitory effects of genistein on cell growth proliferation were associated with a G2/M arrest in cell cycle progression concomitant with a marked inhibition of cyclin B1 and an induction of Cdk inhibitor p21 (WAF1/CIP1) in a p53-independent manner. Following genistein treatment of cells, an increased binding of p21 with Cdk2 and Cdc2 paralleled a significant decrease in Cdc2 and Cdk2 kinase activity with no change in Cdk2 and Cdc2 expression. Genistein also induced the activation of a p21 promoter reporter construct, utilizing a sequence distinct from the p53-binding site. Analysis of deletion constructs of the p21 promoter indicated that the response to genistein could be localized to the 300 base pairs proximal to the transcription start site. These data suggest that genistein may exert a strong anticarcinogenic effect, and that this effect possibly involves an induction of p21, which inhibits the threshold kinase activities of Cdks and associated cyclins, leading to a G2/M arrest in the cell cycle progression.
authors.affiliation: Department of Biology, College of Natural Sciences, Pusan National University, Korea.
authors.forename: Y H
authors.initials: YH
authors.lastname: Choi
authors.forename: W H
authors.initials: WH
authors.lastname: Lee
authors.forename: K Y
authors.initials: KY
authors.lastname: Park
authors.forename: L
authors.initials: L
authors.lastname: Zhang
mesh_terms: D016588:Anticarcinogenic Agents / Q000494:pharmacology*; D016203:CDC2 Protein Kinase / Q000037:antagonists & inhibitors; D042846:CDC2-CDC28 Kinases; D002455:Cell Division / Q000187:drug effects; D019926:Cyclin B / Q000037:antagonists & inhibitors*; D056744:Cyclin B1; D051357:Cyclin-Dependent Kinase 2; D050759:Cyclin-Dependent Kinase Inhibitor p21; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors; D016213:Cyclins / Q000096:biosynthesis* / Q000235:genetics; D016195:G2 Phase / Q000187:drug effects*; D019833:Genistein / Q000494:pharmacology*; D006801:Humans; D008297:Male; D008938:Mitosis / Q000187:drug effects*; D011401:Promoter Regions, Genetic; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D012333:RNA, Messenger / Q000032:analysis; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000502:physiology*
chemical_list: D016588:Anticarcinogenic Agents; C534699:CCNB1 protein, human; C493956:CDKN1A protein, human; D019926:Cyclin B; D056744:Cyclin B1; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D012333:RNA, Messenger; D016159:Tumor Suppressor Protein p53; D019833:Genistein; D017346:Protein Serine-Threonine Kinases; D016203:CDC2 Protein Kinase; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases