title: Influence of cellular ERalpha/ERbeta ratio on the ERalpha-agonist induced proliferation of human T47D breast cancer cells.
abstract: Breast cancer cells show overexpression of estrogen receptor (ER) alpha relative to ERbeta compared to normal breast tissues. This observation has lead to the hypothesis that ERbeta may modulate the proliferative effect of ERalpha. This study investigated how variable cellular expression ratios of the ERalpha and ERbeta modulate the effects on cell proliferation induced by ERalpha or ERbeta agonists, respectively. Using human osteosarcoma (U2OS) ERalpha or ERbeta reporter cells, propyl-pyrazole-triol (PPT) was shown to be a selective ERalpha and diarylpropionitrile (DPN) a preferential ERbeta modulator. The effects of these selective estrogen receptor modulators (SERMs) and of the model compound E2 on the proliferation of T47D human breast cancer cells with tetracycline-dependent expression of ERbeta (T47D-ERbeta) were characterized. E2-induced cell proliferation of cells in which ERbeta expression was inhibited was similar to that of the T47D wild-type cells, whereas this E2-induced cell proliferation was no longer observed when ERbeta expression in the T47D-ERbeta cells was increased. In the T47D-ERbeta cell line, DPN also appeared to be able to suppress cell proliferation when levels of ERbeta expression were high. In the T47D-ERbeta cell line, PPT was unable to suppress cell proliferation at all ratios of ERalpha/ERbeta expression, reflecting its ability to activate only ERalpha and not ERbeta. It is concluded that effects of estrogen-like compounds on cell proliferation are dependent on the actual ERalpha/ERbeta expression levels in these cells or tissues and the potential of the estrogen agonists to activate ERalpha and/or ERbeta.
authors.affiliation: Toxicology Section, Wageningen University, Tuinlaan 5, 6703 HE, Wageningen, The Netherlands. ana.sotoca@wur.nl
authors.forename: Ana M Covaleda
authors.initials: AM
authors.lastname: Sotoca
authors.forename: Hans
authors.initials: H
authors.lastname: van den Berg
authors.forename: Jacques
authors.initials: J
authors.lastname: Vervoort
authors.forename: Paul
authors.initials: P
authors.lastname: van der Saag
authors.forename: Anders
authors.initials: A
authors.lastname: Ström
authors.forename: Jan-Ake
authors.initials: JA
authors.lastname: Gustafsson
authors.forename: Ivonne
authors.initials: I
authors.lastname: Rietjens
authors.forename: Albertinka J
authors.initials: AJ
authors.lastname: Murk
mesh_terms: D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000378:metabolism; D047628:Estrogen Receptor alpha / Q000819:agonists* / Q000235:genetics / Q000378:metabolism; D047629:Estrogen Receptor beta / Q000819:agonists* / Q000235:genetics / Q000378:metabolism; D005260:Female; D005470:Fluorometry; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D006801:Humans; D009570:Nitriles / Q000494:pharmacology*; D010636:Phenols; D011422:Propionates / Q000494:pharmacology*; D011720:Pyrazoles / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D020845:Selective Estrogen Receptor Modulators / Q000494:pharmacology*; D014162:Transfection
chemical_list: C486182:2,3-bis(4-hydroxyphenyl)-propionitrile; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D009570:Nitriles; D010636:Phenols; D011422:Propionates; D011720:Pyrazoles; D012333:RNA, Messenger; D020845:Selective Estrogen Receptor Modulators; C485184:enhanced green fluorescent protein; C486184:4,4',4''-(4-propyl-((1)H)-pyrazole-1,3,5-triyl) tris-phenol; D049452:Green Fluorescent Proteins; D004958:Estradiol