title: Differential effects of 16alpha-hydroxyestrone and 2-methoxyestradiol on cyclin D1 involving the transcription factor ATF-2 in MCF-7 breast cancer cells.
abstract: We studied the effects of 2-methoxyestradiol (2-ME2) and 16alpha-hydroxyestrone (16alpha-OHE1), two metabolites of estradiol (E2), on DNA synthesis, cell cycle progression and cyclin D1 protein levels in estrogen receptor-positive MCF-7 cells. E2 and 16alpha-OHE1 stimulated DNA synthesis, and 2-ME2 inhibited the stimulatory effects of these agents. E2 and 16alpha-OHE1 stimulated the progression of cells from G1 to S phase and this effect was attenuated by 2-ME2. Western blot analysis showed that E2 and 16alpha-OHE1 increased cyclin D1 protein level by about fourfold compared with control. 2-ME2 had no significant effect on cyclin D1; however, it prevented the accumulation of cyclin D1 in the presence of E2 and 16alpha-OHE1. Cells transfected with a cyclin D1 reporter gene and treated with E2 or 16alpha-OHE1 showed 7- and 9.5-fold increase respectively in promoter activity compared with control. This activity was significantly inhibited by 2-ME2. Cyclin D1 transactivation was mediated by the cAMP response element (CRE) region, which binds activating transcription factor 2 (ATF-2). DNA affinity assay showed 2.5- and 3.5-fold increases in ATF-2 binding to CRE in the presence of E2 and 16alpha-OHE1 respectively. The binding of ATF-2 was inhibited by the presence of 2-ME2. These results show that 2-ME2 can downregulate cyclin D1 and thereby cell cycle progression by a mechanism involving the disruption of ATF-2 binding to cyclin D1 promoter.
authors.affiliation: Department of Medicine, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, NJ 08903, USA.
authors.forename: Joan S
authors.initials: JS
authors.lastname: Lewis
authors.forename: T J
authors.initials: TJ
authors.lastname: Thomas
authors.forename: Richard G
authors.initials: RG
authors.lastname: Pestell
authors.forename: Chris
authors.initials: C
authors.lastname: Albanese
authors.forename: Michael A
authors.initials: MA
authors.lastname: Gallo
authors.forename: Thresia
authors.initials: T
authors.lastname: Thomas
mesh_terms: D000077584:2-Methoxyestradiol; D051698:Activating Transcription Factor 2; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism*; D019938:Cyclin D1 / Q000187:drug effects* / Q000378:metabolism; D004261:DNA Replication / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D006894:Hydroxyestrones / Q000494:pharmacology*; D014157:Transcription Factors / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: C497105:ATF2 protein, human; D051698:Activating Transcription Factor 2; D017362:Cyclic AMP Response Element-Binding Protein; D006894:Hydroxyestrones; D014157:Transcription Factors; D019938:Cyclin D1; C026702:16-hydroxyestrone; D004958:Estradiol; D000077584:2-Methoxyestradiol; D048051:p38 Mitogen-Activated Protein Kinases