title: Ethanol-induced ligand-independent activation of ERalpha mediated by cyclic AMP/PKA signaling pathway: an in vitro study on MCF-7 breast cancer cells.
abstract: Alcohol consumption is an increased risk factor for hormone-dependent breast cancer but the underlying molecular bases are unknown. Several studies suggest that ethanol could activate the estrogen signaling pathway. We have performed an in vitro study in order to investigate the molecular players involved in this phenomenon. Exposure of MCF-7 breast cancer cells to ethanol induced an increase in the mRNA level of two well known estrogen target genes: progesterone receptor (PR) and pS2. This result was confirmed by an increase in luciferase activity in pEREtkLuc-transfected MCF-7 cells exposed to ethanol. These effects, whose intensity was similar to those of E2, were observed also in steroid-free medium and were inhibited by the antiestrogen ICI 182,780. This suggested a ligand-independent activation of ERalpha that was confirmed by the absence of ERalpha proteolysis in ethanol-treated cells. Using PKA inhibitor (H89), the study of phospho-CREB by Western blot and transfection experiments with a CRE-reporter construct demonstrated that PKA was involved in ethanol-induced transcription of ERalpha target genes. Adenylyl cyclase inhibition impaired the activation of estrogen signaling pathway induced by ethanol. The results obtained in vitro, are discussed in regard to alcohol consumption and relevance to humans.
authors.affiliation: EA 3442 Aspects Cellulaires et Moléculaires de la Reproduction et du Développement, Nancy-Université, Université Henri Poincaré, Faculté des Sciences, 54506, Vandoeuvre-lès-Nancy, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Etique
authors.forename: Stephane
authors.initials: S
authors.lastname: Flament
authors.forename: Julie
authors.initials: J
authors.lastname: Lecomte
authors.forename: Isabelle
authors.initials: I
authors.lastname: Grillier-Vuissoz
mesh_terms: D001943:Breast Neoplasms; D045744:Cell Line, Tumor; D000242:Cyclic AMP / Q000502:physiology*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000502:physiology*; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000502:physiology*; D000431:Ethanol / Q000633:toxicity*; D000077267:Fulvestrant; D006801:Humans; D008024:Ligands; D011980:Receptors, Progesterone / Q000235:genetics; D015398:Signal Transduction / Q000502:physiology*; D000071163:Trefoil Factor-1; D025521:Tumor Suppressor Proteins / Q000235:genetics
chemical_list: C115163:CREB1 protein, human; D017362:Cyclic AMP Response Element-Binding Protein; D047628:Estrogen Receptor alpha; D008024:Ligands; D011980:Receptors, Progesterone; C051838:TFF1 protein, human; D000071163:Trefoil Factor-1; D025521:Tumor Suppressor Proteins; D000077267:Fulvestrant; D000431:Ethanol; D004958:Estradiol; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases