title: Estrogen induces adenosine deaminase gene expression in MCF-7 human breast cancer cells: role of estrogen receptor-Sp1 interactions.
abstract: Adenosine deaminase (ADA) gene expression is induced by 17beta-estradiol (E2) in MCF-7 human breast cancer cells, whereas the antiestrogens 4'-hydroxytamoxifen and ICI 182,780 exhibit partial estrogen receptor (ER) agonist/antagonist and antagonist activities, respectively. Previous studies have shown that the -211 to +11 region of the ADA gene promoter contains six GC-rich sites (I-VI) that bind Sp1 protein, and these elements are required for high basal expression. In transient transfection studies with pADA211, which contains the -211 to +11 ADA gene promoter linked to a bacterial chloramphenicol acetyl transferase (CAT) reporter gene, E2 and tamoxifen (but not ICI 182,780) induced CAT activity. Ligand-induced transactivation was observed only in cells cotransfected with expression plasmids for wild-type ER or HE11, which does not contain the DNA-binding domain of the ER. Cotransfection with HE15 and HE19, which contain the DNA-binding domain and activation function-1 (AF-1) and AF-2 of the ER, respectively, did not result in E2-induced activity. Subsequent deletion analysis of the ADA gene promoter showed that Sp1 binding site IV (-79 to -73) was primarily responsible for hormone responsiveness. ER activation of ADA gene expression is another example of an E2-induced gene that is dependent on ER/Sp1 interactions with a site-specific GC-rich motif.
authors.affiliation: Department of Veterinary Physiology and Pharmacology, Texas A&M University, College Station 77843-4466, USA.
authors.forename: W
authors.initials: W
authors.lastname: Xie
authors.forename: R
authors.initials: R
authors.lastname: Duan
authors.forename: S
authors.initials: S
authors.lastname: Safe
mesh_terms: D000243:Adenosine Deaminase / Q000235:genetics*; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004958:Estradiol / Q000494:pharmacology*; D004965:Estrogen Antagonists / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D011960:Receptors, Estrogen / Q000378:metabolism*; D016329:Sp1 Transcription Factor / Q000378:metabolism*; D014407:Tumor Cells, Cultured
chemical_list: D004965:Estrogen Antagonists; D011960:Receptors, Estrogen; D016329:Sp1 Transcription Factor; D004958:Estradiol; D004247:DNA; D015500:Chloramphenicol O-Acetyltransferase; D000243:Adenosine Deaminase