title: Transcriptional activation of breast cancer-associated gene 2 by estrogen receptor.
abstract: RNF115, or Breast Cancer-Associated Gene 2 (BCA2), encodes a RING-finger ubiquitin E3 ligase, expression of which was associated with estrogen receptor (ER)-positive status in human breast tumors. Although the BCA2 promoter contains several estrogen response element (ERE) half-sites, the role of ER in the regulation of BCA2 transcription has not been reported. The aim of this study is to investigate the molecular mechanism by which estrogen regulates BCA2 transcription. BCA2 mRNA and protein levels were examined by RT-PCR and Western blot analysis, respectively, and localization was assessed by immunofluorescence. BCA2 promoter activity in response to E(2) was tested by a dual luciferase reporter assay and ER binding to the BCA2 promoter was examined by chromatin immunoprecipitation assay. We found that BCA2 mRNA and protein levels are regulated by estrogen in ER-positive MCF7 breast cancer cells and MDA MB 231 cells stably transfected with ER. Estrogen treatment in hormonal depleted MCF7 and MDA MB 231/ER stably transfected cells resulted in increased nuclear ER and cytoplasmic and nuclear BCA2 staining. Cycloheximide is not able to inhibit BCA2 mRNA levels, suggesting potential BCA2 regulation at the transcriptional level. Anti-estrogens like tamoxifen and ICI 182 178 counteracted E(2)-induced BCA2 protein and knockdown of ER by ER siRNA resulted in a significant decrease in BCA2 protein and a lower nuclear expression pattern. Estrogen treatment lead to a significant increase in BCA2 promoter response, associated with increased binding of ER to the ERE region of the BCA2 promoter. BCA2 is therefore a newly identified transcriptional target of estrogen receptor.
authors.affiliation: Barbara Ann Karmanos Cancer Institute and Departments of Oncology, Pharmacology and Pathology, School of Medicine, Wayne State University, 540.1 Hudson Webber Cancer Research Building, Mail Code HW05AO, 4100 John R Road, Detroit, MI 48201-2013, USA.
authors.forename: Fathima R
authors.initials: FR
authors.lastname: Kona
authors.forename: Karri
authors.initials: K
authors.lastname: Stark
authors.forename: Luke
authors.initials: L
authors.lastname: Bisoski
authors.forename: Daniela
authors.initials: D
authors.lastname: Buac
authors.forename: Qiuzhi
authors.initials: Q
authors.lastname: Cui
authors.forename: Q Ping
authors.initials: QP
authors.lastname: Dou
mesh_terms: D001943:Breast Neoplasms; D047369:Chromatin Immunoprecipitation; D003513:Cycloheximide / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology / Q000502:physiology; D020847:Estrogen Receptor Modulators / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000819:agonists / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D017930:Genes, Reporter; D006801:Humans; D049410:Luciferases, Renilla / Q000096:biosynthesis / Q000235:genetics; D061986:MCF-7 Cells; D011485:Protein Binding; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D034622:RNA Interference; D020218:Response Elements; D015533:Transcriptional Activation; D044767:Ubiquitin-Protein Ligases / Q000235:genetics* / Q000378:metabolism
chemical_list: C506487:ESR1 protein, human; D020847:Estrogen Receptor Modulators; D047628:Estrogen Receptor alpha; D011500:Protein Synthesis Inhibitors; D004958:Estradiol; D003513:Cycloheximide; D049410:Luciferases, Renilla; C506934:RNF115 protein, human; D044767:Ubiquitin-Protein Ligases