title: Estrogen receptor (ER) beta regulates ERalpha expression in stromal cells derived from ovarian endometriosis.
abstract: BACKGROUND
  Estradiol and its nuclear receptors, estrogen receptor (ER) alpha and ERbeta, play critical roles in endometrium and endometriosis. Levels of ERbeta, due to pathological hypomethylation of its promoter, are significantly higher in endometriotic vs. endometrial tissue and stromal cells, whereas ERalpha levels are lower in endometriosis. Estradiol regulates ERalpha gene expression via its alternatively used promoters A, B, and C.
  
  
  OBJECTIVE
  The aim of the study was to determine whether high levels of ERbeta in endometriotic stromal cells from ovarian endometriomas regulate ERalpha gene expression.
  
  
  RESULTS
  ERbeta knockdown significantly increased ERalpha mRNA and protein levels in endometriotic stromal cells. Conversely, ERbeta overexpression in endometrial stromal cells decreased ERalpha mRNA and protein levels. ERbeta knockdown significantly decreased proliferation of endometriotic stromal cells. Chromatin immunoprecipitation assays demonstrated that estradiol enhanced ERbeta binding to nonclassical activator protein 1 and specificity protein 1 motifs in the ERalpha gene promoters A and C and a classic estrogen response element in promoter B in endometriotic stromal cells.
  
  
  CONCLUSIONS
  High levels of ERbeta suppress ERalpha expression and response to estradiol in endometrial and endometriotic stromal cells via binding to classic and nonclassic DNA motifs in alternatively used ERalpha promoters. ERbeta also regulates cell cycle progression and might contribute to proliferation of endometriotic stromal cells. We speculate that a significantly increased ratio of ERbeta:ERalpha in endometriotic tissues may also suppress progesterone receptor expression and contribute to progesterone resistance. Thus, ERbeta may serve as a significant therapeutic target for endometriosis.
authors.affiliation: Division of Reproductive Biology Research, Department of Obstetrics and Gynecology, Feinberg School of Medicine at Northwestern University, 303 East Superior Street, 4-123, Chicago, Illinois 60611, USA.
authors.forename: Elena
authors.initials: E
authors.lastname: Trukhacheva
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Lin
authors.forename: Scott
authors.initials: S
authors.lastname: Reierstad
authors.forename: You-Hong
authors.initials: YH
authors.lastname: Cheng
authors.forename: Magdy
authors.initials: M
authors.lastname: Milad
authors.forename: Serdar E
authors.initials: SE
authors.lastname: Bulun
mesh_terms: D000328:Adult; D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics; D002478:Cells, Cultured; D004715:Endometriosis / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D004958:Estradiol / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000235:genetics* / Q000378:metabolism; D047629:Estrogen Receptor beta / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D008875:Middle Aged; D010049:Ovarian Diseases / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000494:pharmacology; D017154:Stromal Cells / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D014162:Transfection
chemical_list: D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D034741:RNA, Small Interfering; D004958:Estradiol