title: Transcriptional activation of deoxyribonucleic acid polymerase alpha gene expression in MCF-7 cells by 17 beta-estradiol.
abstract: Treatment of MCF-7 human breast cancer cells with 17beta-estradiol (E(2)) results in increased DNA synthesis and cell proliferation and enhanced enzyme activities associated with purine/pyrimidine biosynthesis. The mechanism of enhanced DNA polymerase alpha activity was investigated by analysis of the promoter region of this gene. E(2) induced luciferase (reporter gene) activity in MCF-7 cells transfected with pDNAP1, pDNAP2, and pDNAP3 containing -1515 to +45, -248 to +45 and -116 to +45 inserts from the DNA polymerase alpha gene promoter, whereas no induction was observed with pDNAP4 (-65 to +45 insert). The induction response was dependent on cotransfection with estrogen receptor alpha (ER(alpha)), and transactivation was also observed with a mutant ER(alpha) that did not express the DNA-binding domain. Subsequent functional, DNA binding, and DNA footprinting studies showed that a GC-rich region at -106 to -100 was required for E(2)-mediated transactivation, and Sp1 protein, but not ER(alpha), bound this sequence. Transcriptional activation of DNA polymerase alpha by E(2) is associated with ER(alpha)/Sp1 action at a proximal GC-rich promoter sequence, and this gene is among a growing list of E(2)-responsive genes that are induced via ER(alpha)/Sp1 protein interactions that do not require direct binding of the hormone receptor to DNA.
authors.affiliation: Department of Veterinary Physiology and Pharmacology , Texas A&M University, College Station, Texas 77843, USA.
authors.forename: I
authors.initials: I
authors.lastname: Samudio
authors.forename: C
authors.initials: C
authors.lastname: Vyhlidal
authors.forename: F
authors.initials: F
authors.lastname: Wang
authors.forename: M
authors.initials: M
authors.lastname: Stoner
authors.forename: I
authors.initials: I
authors.lastname: Chen
authors.forename: M
authors.initials: M
authors.lastname: Kladde
authors.forename: R
authors.initials: R
authors.lastname: Barhoumi
authors.forename: R
authors.initials: R
authors.lastname: Burghardt
authors.forename: S
authors.initials: S
authors.lastname: Safe
mesh_terms: D001943:Breast Neoplasms / Q000235:genetics*; D018983:DNA Footprinting; D004256:DNA Polymerase I / Q000235:genetics* / Q000378:metabolism; D004790:Enzyme Induction / Q000502:physiology; D004958:Estradiol / Q000494:pharmacology*; D047628:Estrogen Receptor alpha; D005260:Female; D015870:Gene Expression / Q000187:drug effects* / Q000502:physiology*; D006801:Humans; D007150:Immunohistochemistry; D009687:Nuclear Proteins / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics / Q000502:physiology; D011960:Receptors, Estrogen / Q000502:physiology; D016329:Sp1 Transcription Factor / Q000502:physiology; D015533:Transcriptional Activation / Q000502:physiology*; D014407:Tumor Cells, Cultured
chemical_list: D047628:Estrogen Receptor alpha; D009687:Nuclear Proteins; D011960:Receptors, Estrogen; D016329:Sp1 Transcription Factor; D004958:Estradiol; D004256:DNA Polymerase I