title: Estrogen-induced upregulation and 3'-UTR shortening of CDC6.
abstract: 3'-Untranslated region (UTR) shortening of mRNAs via alternative polyadenylation (APA) has important ramifications for gene expression. By using proximal APA sites and switching to shorter 3'-UTRs, proliferating cells avoid miRNA-mediated repression. Such APA and 3'-UTR shortening events may explain the basis of some of the proto-oncogene activation cases observed in cancer cells. In this study, we investigated whether 17 β-estradiol (E2), a potent proliferation signal, induces APA and 3'-UTR shortening to activate proto-oncogenes in estrogen receptor positive (ER+) breast cancers. Our initial probe based screen of independent expression arrays suggested upregulation and 3'-UTR shortening of an essential regulator of DNA replication, CDC6 (cell division cycle 6), upon E2 treatment. We further confirmed the E2- and ER-dependent upregulation and 3'UTR shortening of CDC6, which lead to increased CDC6 protein levels and higher BrdU incorporation. Consequently, miRNA binding predictions and dual luciferase assays suggested that 3'-UTR shortening of CDC6 was a mechanism to avoid 3'-UTR-dependent negative regulations. Hence, we demonstrated CDC6 APA induction by the proliferative effect of E2 in ER+ cells and provided new insights into the complex regulation of APA. E2-induced APA is likely to be an important but previously overlooked mechanism of E2-responsive gene expression.
authors.affiliation: Department of Biological Sciences, METU (Middle East Technical University), Universiteler Mah, Dumlupınar Blv. No. 1, 06800 Çankaya, Ankara, Turkey.
authors.forename: Begum H
authors.initials: BH
authors.lastname: Akman
authors.forename: Tolga
authors.initials: T
authors.lastname: Can
authors.forename: A Elif
authors.initials: AE
authors.lastname: Erson-Bensan
mesh_terms: D020413:3' Untranslated Regions; D018797:Cell Cycle Proteins / Q000096:biosynthesis / Q000235:genetics*; D002460:Cell Line; D004958:Estradiol / Q000494:pharmacology*; D004967:Estrogens / Q000494:pharmacology*; D006801:Humans; D035683:MicroRNAs / Q000378:metabolism; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000235:genetics*; D026723:Polyadenylation / Q000187:drug effects; D020033:Protein Isoforms / Q000096:biosynthesis / Q000235:genetics; D000090063:Proto-Oncogene Mas; D015854:Up-Regulation
chemical_list: D020413:3' Untranslated Regions; C103706:CDC6 protein, human; D018797:Cell Cycle Proteins; D004967:Estrogens; C000715470:MAS1 protein, human; D035683:MicroRNAs; D009687:Nuclear Proteins; D020033:Protein Isoforms; D000090063:Proto-Oncogene Mas; D004958:Estradiol