title: Widespread estrogen-dependent repression of micrornas involved in breast tumor cell growth.
abstract: Altered expression of microRNAs (miRNA), an abundant class of small nonprotein-coding RNAs that mostly function as negative regulators of protein-coding gene expression, is common in cancer. Here, we analyze the regulation of miRNA expression in response to estrogen, a steroid hormone that is involved in the development and progression of breast carcinomas and that is acting via the estrogen receptors (ER) transcription factors. We set out to thoroughly describe miRNA expression, by using miRNA microarrays and real-time reverse transcription-PCR (RT-PCR) experiments, in various breast tumor cell lines in which estrogen signaling has been induced by 17beta-estradiol (E(2)). We show that the expression of a broad set of miRNAs decreases following E(2) treatment in an ER-dependent manner. We further show that enforced expression of several of the repressed miRNAs reduces E(2)-dependent cell growth, thus linking expression of specific miRNAs with estrogen-dependent cellular response. In addition, a transcriptome analysis revealed that the E(2)-repressed miR-26a and miR-181a regulate many genes associated with cell growth and proliferation, including the progesterone receptor gene, a key actor in estrogen signaling. Strikingly, miRNA expression is also regulated in breast cancers of women who had received antiestrogen neoadjuvant therapy. Overall, our data indicate that the extensive alterations in miRNA regulation upon estrogen signaling pathway play a key role in estrogen-dependent functions and highlight the utility of considering miRNA expression in the understanding of antiestrogen resistance of breast cancer.
authors.affiliation: Institut National de la Sante et de la Recherche Medicale U563, Institut Claudius Regaud, and Université de Toulouse, UPS, Centre de Physiopathologie de Toulouse Purpan, Toulouse, France.
authors.forename: Gérard
authors.initials: G
authors.lastname: Maillot
authors.forename: Magali
authors.initials: M
authors.lastname: Lacroix-Triki
authors.forename: Sandra
authors.initials: S
authors.lastname: Pierredon
authors.forename: Lise
authors.initials: L
authors.lastname: Gratadou
authors.forename: Sabine
authors.initials: S
authors.lastname: Schmidt
authors.forename: Vladimir
authors.initials: V
authors.lastname: Bénès
authors.forename: Henri
authors.initials: H
authors.lastname: Roché
authors.forename: Florence
authors.initials: F
authors.lastname: Dalenc
authors.forename: Didier
authors.initials: D
authors.lastname: Auboeuf
authors.forename: Stefania
authors.initials: S
authors.lastname: Millevoi
authors.forename: Stéphan
authors.initials: S
authors.lastname: Vagner
mesh_terms: D000730:Androstadienes / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000494:pharmacology; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D015152:Blotting, Northern; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000473:pathology; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000188:drug therapy / Q000235:genetics / Q000473:pathology; D049109:Cell Proliferation / Q000187:drug effects; D004965:Estrogen Antagonists / Q000494:pharmacology; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D009361:Neoplasm Invasiveness; D010865:Pilot Projects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013629:Tamoxifen / Q000494:pharmacology; D016896:Treatment Outcome
chemical_list: D000730:Androstadienes; D000970:Antineoplastic Agents; D014408:Biomarkers, Tumor; D004965:Estrogen Antagonists; D004967:Estrogens; D035683:MicroRNAs; D012333:RNA, Messenger; D013629:Tamoxifen; C056516:exemestane