title: Estrogen receptor alpha and activating protein-1 mediate estrogen responsiveness of the progesterone receptor gene in MCF-7 breast cancer cells.
abstract: The progesterone receptor (PR) gene is activated by estrogen in MCF-7 human breast cancer cells. Although the human PR gene does not contain an estrogen response element (ERE), we have identified a putative activating protein-1 (AP-1) site at +90 in the PR gene that was hypersensitive to deoxyribonuclease I cleavage in genomic Southern analysis, bound purified Fos and Jun, formed a complex with Fos/Jun heterodimers present in MCF-7 nuclear extracts in gel mobility shift assays, and functioned as an estrogen-responsive enhancer in transient cotransfection assays. When the +90 AP-1 site was mutated in the context of the PR gene, estrogen responsiveness was significantly decreased. Purified estrogen receptor (ER) enhanced binding of Fos and Jun to the +90 AP-1 site and bound to an adjacent imperfect ERE half-site. Mutating this ERE half-site diminished the binding of ER, Fos, and Jun and decreased transcription. Chromatin immunoprecipitation assays demonstrated that the ER, Fos, and Jun were present at the +90 AP-1 site in the endogenous PR gene only after treatment of MCF-7 cells with estrogen. These studies suggest that the cooperative interaction of the ER with Fos and Jun proteins helps confer estrogen responsiveness to the endogenous PR gene.
authors.affiliation: Department of Molecular and Integrative Physiology, University of Illinois, Urbana, Illinois 61801, USA.
authors.forename: Larry N
authors.initials: LN
authors.lastname: Petz
authors.forename: Yvonne S
authors.initials: YS
authors.lastname: Ziegler
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Loven
authors.forename: Ann M
authors.initials: AM
authors.lastname: Nardulli
mesh_terms: D001665:Binding Sites; D015139:Blotting, Southern; D001943:Breast Neoplasms / Q000378:metabolism*; D002467:Cell Nucleus / Q000737:chemistry; D004247:DNA / Q000378:metabolism; D003850:Deoxyribonuclease I / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology; D047628:Estrogen Receptor alpha; D004967:Estrogens / Q000494:pharmacology*; D006801:Humans; D016296:Mutagenesis; D011401:Promoter Regions, Genetic; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D011960:Receptors, Estrogen / Q000502:physiology*; D011980:Receptors, Progesterone / Q000235:genetics*; D020218:Response Elements; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000502:physiology*; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D047628:Estrogen Receptor alpha; D004967:Estrogens; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; D018808:Transcription Factor AP-1; D004958:Estradiol; D004247:DNA; D003850:Deoxyribonuclease I