title: Progesterone regulates transcription of the p21(WAF1) cyclin- dependent kinase inhibitor gene through Sp1 and CBP/p300.
abstract: Progesterone has biphasic effects on proliferation of breast cancer cells; it stimulates growth in the first cell cycle, then arrests cells at G1/S of the second cycle accompanied by up-regulation of the cyclin-dependent kinase inhibitor, p21. We now show that progesterone regulates transcription of the p21 promoter by an unusual mechanism. This promoter lacks a canonical progesterone response element. Instead, progesterone receptors (PRs) interact with the promoter through the transcription factor Sp1 at the third and fourth of six Sp1 binding sites located downstream of nucleotide 154. Mutation of Sp1 site 3 eliminates basal transcription, and mutation of sites 3 and 4 eliminates transcriptional up-regulation by progesterone. Progesterone-mediated transcription is further prevented by overexpression of E1A, suggesting that CBP/p300 is required. Indeed, in HeLa cells, Sp1 and CBP/p300 associate with stably integrated flag-tagged PRs in a multiprotein complex. Since many signals converge on p21, cross-talk between PRs and other factors co-localized on the p21 promoter, may explain how progesterone can be either proliferative or differentiative in different target cells.
authors.affiliation: Departments of Medicine and Pathology, and the Molecular Biology Program, University of Colorado Health Sciences Center, Denver, Colorado 80262, USA.
authors.forename: G I
authors.initials: GI
authors.lastname: Owen
authors.forename: J K
authors.initials: JK
authors.lastname: Richer
authors.forename: L
authors.initials: L
authors.lastname: Tung
authors.forename: G
authors.initials: G
authors.lastname: Takimoto
authors.forename: K B
authors.initials: KB
authors.lastname: Horwitz
mesh_terms: D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D009687:Nuclear Proteins / Q000378:metabolism; D011374:Progesterone / Q000494:pharmacology*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011980:Receptors, Progesterone / Q000378:metabolism; D015398:Signal Transduction; D016329:Sp1 Transcription Factor / Q000378:metabolism; D015534:Trans-Activators; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects*; D014407:Tumor Cells, Cultured
chemical_list: C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D009687:Nuclear Proteins; D011980:Receptors, Progesterone; D016329:Sp1 Transcription Factor; D015534:Trans-Activators; D014157:Transcription Factors; D011374:Progesterone