title: Effects of genistein on cell proliferation and cell cycle arrest in nonneoplastic human mammary epithelial cells: involvement of Cdc2, p21(waf/cip1), p27(kip1), and Cdc25C expression.
abstract: Genistein, a soy isoflavone, has been reported to inhibit the multiplication of numerous neoplastic cells, including those in the breast. However, there is limited information on the effect of genistein on nonneoplastic human breast cells. In the present studies, genistein inhibited proliferation of, and DNA synthesis in, the nonneoplastic human mammary epithelial cell line MCF-10F with an IC(50) of approximately 19-22 microM, and caused a reversible G2/M block in cell cycle progression. Genistein treatment (45 microM) increased the phosphorylation of Cdc2 by 3-fold, decreased the activity of Cdc2 by 70% after 8 hr, and by 24 hr reduced the expression of Cdc2 by 70%. In addition, genistein enhanced the expression of the cell cycle inhibitor p21(waf/cip1) by 10- to 15-fold, increased p21(waf/cip1) association with Cdc2 by 2-fold, and increased the expression of the tumor suppressor p53 by 2.8-fold. Genistein did not alter the expression of p27(kip1) significantly. Furthermore, genistein inhibited the expression of the cell cycle-associated phosphatase Cdc25C by 80%. From these results, we conclude that genistein inhibits the growth of nonneoplastic MCF-10F human breast cells by preventing the G2/M phase transition, induces the expression of the cell cycle inhibitor p21(waf/cip1) as well as its interaction with Cdc2, and inhibits the activity of Cdc2 in a phosphorylation-related manner. Down-regulation of the cell cycle-associated phosphatase Cdc25C combined with up-regulation of p21(waf/cip1) expression appear to be important mechanisms by which genistein decreases Cdc2 kinase activity and causes G2 cell cycle arrest.
authors: Department of Food Science and Human Nutrition, University of Illinois, 905 South Goodwin Avenue, 61801, Urbana, IL, USA
authors: R S
authors: RS
authors: Frey
authors: J
authors: J
authors: Li
authors: K W
authors: KW
authors: Singletary
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D016203:CDC2 Protein Kinase / Q000096:biosynthesis / Q000502:physiology; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000096:biosynthesis / Q000502:physiology; D002455:Cell Division / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016213:Cyclins / Q000096:biosynthesis / Q000502:physiology; D015536:Down-Regulation / Q000187:drug effects; D004847:Epithelial Cells / Q000187:drug effects / Q000473:pathology; D005786:Gene Expression Regulation / Q000187:drug effects*; D019833:Genistein / Q000494:pharmacology*; D006801:Humans; D015674:Mammary Neoplasms, Animal / Q000473:pathology; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis / Q000502:physiology; D010766:Phosphorylation / Q000187:drug effects; D011494:Protein Kinases / Q000378:metabolism; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins; D015854:Up-Regulation / Q000187:drug effects; D020687:cdc25 Phosphatases / Q000096:biosynthesis / Q000502:physiology
chemical_list: D000970:Antineoplastic Agents; C493956:CDKN1A protein, human; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D008869:Microtubule-Associated Proteins; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D019833:Genistein; D011494:Protein Kinases; C102333:histone H1 kinase; D016203:CDC2 Protein Kinase; C517009:CDC25C protein, human; D020687:cdc25 Phosphatases