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Regulation of estrogen receptor levels by ligand-induced release of compound(s) in MCF-7 cells

par Seo, Hye-Sook ;Larsimont, Denis ;Ma, Yan ;Laïos, Ioanna;Leclercq, Guy
Référence Molecular and cellular endocrinology, 164, 1-2, page (19-29)
Publication Publié, 2000-06

Article révisé par les pairs

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Résumé :

In MCF-7 cells, estradiol (E2) and pure antiestrogens (AEs) decrease estrogen receptor α (ER) levels, while AEs with partial estrogenic activity lead to ER α accumulation. Using immunocytochemistry, we found that cells pre-exposed to one of such ligands, when plated with untreated cells, led to similar ER changes in the latter. Conditioned media (CM(s)) prepared from stimulated cells displayed identical regulatory effects even after strong dilution; they also modulated ERE-dependent transcriptional activity. Evaluation of residual ligand concentrations in CM(s) rejected the possibility of a major interference of the former. Cycloheximide, which inhibits E2-induced down-regulation, failed to block the influence of CM(E2) in agreement with this view. DCC-treatment of CM(s) abrogated their effects, suggesting the release of hydrophobic compound(s) which regulate ER and/or amplify the effect of extremely low amounts of residual ligands. Such a release appears independent of ER since CM(s) from MDA-MB-231 cells (ER- negative) were effective as their autologous media on MCF-7 cells. (C) 2000 Elsevier Science Ireland Ltd.