Estrogen-induced upregulation and 3'-UTR shortening of CDC6

• Published in: Nucleic acids research Vol. 40; no. 21; pp. 10679 - 10688
• Main Authors: Akman, Begum H, Can, Tolga, Erson-Bensan, A Elif
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 01.11.2012
• Subjects: 3' Untranslated Regions; Breast cancer; Cdc6 protein; Cell Cycle Proteins - biosynthesis; Cell Cycle Proteins - genetics; Cell division; Cell Line; DNA biosynthesis; Estradiol - pharmacology; Estrogen receptors; Estrogens - pharmacology; Fluorescent indicators; Gene expression; Gene Regulation, Chromatin and Epigenetics; Humans; MicroRNAs - metabolism; miRNA; Nuclear Proteins - biosynthesis; Nuclear Proteins - genetics; Polyadenylation; Polyadenylation - drug effects; Protein Isoforms - biosynthesis; Protein Isoforms - genetics; Proto-oncogenes; Replication; Up-Regulation
• ISSN: 0305-1048; 1362-4962
• DOI: 10.1093/nar/gks855

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.