title: Long-term exposure to dehydroepiandrosterone affects the transcriptional activity of the glucocorticoid receptor.
abstract: Although the antiglucocorticoid effects of dehydroepiandrosterone (DHEA) have been demonstrated in vivo in many systems, controversial results have been reported by in vitro studies. In order to elucidate the long-term antiglucocorticoid effects of DHEA in vitro in a context more physiological than what proposed by previous works, we set up a system consisting of a carcinoma cell line relying on endogenously produced glucocorticoid receptor (GR) and stably expressing a reporter gene ErbB-2 under the control of a GR-dependent MMTV promoter. These cells grown in presence of low levels of serum glucocorticoids (GC) showed a basal translocation and activity of endogenous GR. The cells reacted to high concentrations of dexamethasone increasing GR nuclear import, although down-regulating receptor expression, and enhancing GR-dependent transcriptional activity, as shown by EMSA assay and expression of the reporter gene ErbB-2. The response to GC was also functional since the increase of ErbB-2 boosted cellular growth. On the contrary, 72h of incubation with DHEA diminished basal GR-dependent reporter expression and abated cellular proliferation. Analysing molecular mechanisms responsible for this failed transcriptional activity, upon prolonged treatment with DHEA we observed a slow nuclear import of GR not followed by its recruitment to DNA. These data add novel information about the long-term effects of DHEA in vitro.
authors.affiliation: Department of Genetics, Biology and Biochemistry, University of Turin, Via Santena 5bis, 10126 Turin, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Saponaro
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Guarnieri
authors.forename: Gian Piero
authors.initials: GP
authors.lastname: Pescarmona
authors.forename: Francesca
authors.initials: F
authors.lastname: Silvagno
mesh_terms: D000818:Animals; D004268:DNA-Binding Proteins / Q000378:metabolism; D003687:Dehydroepiandrosterone / Q000494:pharmacology*; D051379:Mice; D008954:Models, Biological; D021381:Protein Transport / Q000187:drug effects; D011965:Receptors, Glucocorticoid / Q000378:metabolism*; D013995:Time; D015533:Transcriptional Activation / Q000187:drug effects*; D014407:Tumor Cells, Cultured
chemical_list: D004268:DNA-Binding Proteins; D011965:Receptors, Glucocorticoid; D003687:Dehydroepiandrosterone