title: Low-dose genistein induces cyclin-dependent kinase inhibitors and G(1) cell-cycle arrest in human prostate cancer cells.
abstract: Genistein, a naturally occurring isoflavone found chiefly in soy products, reportedly has antiprostate cancer effects, but the mechanisms underlying these effects are unknown. We studied the antiproliferative and apoptosis-inducing effects of genistein in the androgen-sensitive human prostate cancer cell line LNCaP. Viable cell number was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay; cell-cycle progression and apoptosis were evaluated by flow cytometry; apoptosis was also assessed by a histone enzyme-linked immunosorbent assay; and the expression of several cell-cycle- and apoptosis-related genes and their gene products was determined by northern blot analysis, western blot analysis, and/or assays based on polymerase chain reaction. Physiologic concentrations of genistein (< or = 20 microM) decreased LNCaP viable cell number in a dose-dependent manner, induced a G(1) cell-cycle block, decreased prostate-specific antigen mRNA expression, and increased p27(KIP1) and p21(WAF1) (mRNA and protein) but had no effect on apoptosis or the mRNA expression of the apoptosis- and cell-cycle-related markers bcl-2, bax, Rb, and proliferating cell nuclear antigen. Higher concentrations of genistein (> 20 microM) did induce apoptosis. We conclude that genistein (at physiologic concentrations) exerts potent antiproliferative effects on LNCaP cells by inducing a G(1) cell-cycle block. The antiproliferative effects of genistein may be mediated by increased levels of p27(KIP1) and p21(WAF1), which are negative cell-cycle regulators that act as cyclin-dependent kinase inhibitors and that have been recently linked with prostate carcinogenesis. These findings may provide insights into the mechanisms underlying the apparent antiprostate cancer effects of soy consumption observed in epidemiologic studies.
authors.affiliation: Department of Epidemiology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Shen
authors.forename: R D
authors.initials: RD
authors.lastname: Klein
authors.forename: Q
authors.initials: Q
authors.lastname: Wei
authors.forename: Y
authors.initials: Y
authors.lastname: Guan
authors.forename: J H
authors.initials: JH
authors.lastname: Contois
authors.forename: T T
authors.initials: TT
authors.lastname: Wang
authors.forename: S
authors.initials: S
authors.lastname: Chang
authors.forename: S D
authors.initials: SD
authors.lastname: Hursting
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D002452:Cell Count; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016213:Cyclins / Q000096:biosynthesis* / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D016193:G1 Phase / Q000187:drug effects*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D016147:Genes, Tumor Suppressor / Q000187:drug effects; D018816:Genes, cdc / Q000187:drug effects; D019833:Genistein / Q000494:pharmacology*; D006131:Growth Inhibitors / Q000494:pharmacology; D006801:Humans; D008297:Male; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis* / Q000235:genetics; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology*; D014407:Tumor Cells, Cultured / Q000187:drug effects; D025521:Tumor Suppressor Proteins
chemical_list: D000970:Antineoplastic Agents; C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D006131:Growth Inhibitors; D008869:Microtubule-Associated Proteins; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D019833:Genistein