title: Estrogen receptor beta impacts hormone-induced alternative mRNA splicing in breast cancer cells.
abstract: BACKGROUND
  Estrogens play an important role in breast cancer (BC) development and progression; when the two isoforms of the estrogen receptor (ERα and ERβ) are co-expressed each of them mediate specific effects of these hormones in BC cells. ERβ has been suggested to exert an antagonist role toward the oncogenic activities of ERα, and for this reason it is considered an oncosuppressor. As clinical evidence regarding a prognostic role for this receptor subtype in hormone-responsive BC is still limited and conflicting, more knowledge is required on the biological functions of ERβ in cancer cells. We have previously described the ERβ and ERα interactomes from BC cells, identifying specific and distinct patterns of protein interactions for the two receptors. In particular, we identified factors involved in mRNA splicing and maturation as important components of both ERα and ERβ pathways. Guided by these findings, here we performed RNA sequencing to investigate in depth the differences in the early transcriptional events and RNA splicing patterns induced by estradiol in cells expressing ERα alone or ERα and ERβ.
  
  
  RESULTS
  Exon skipping was the most abundant splicing event in the post-transcriptional regulation by estradiol. We identified several splicing events induced by ERα alone and by ERα+ERβ, demonstrating for the first time that ERβ significantly affects estrogen-induced splicing in BC cells, as revealed by modification of a subset of ERα-dependent splicing by ERβ, as well as by the presence of splicing isoforms only in ERβ+cells. In particular, we observed that ERβ+BC cell lines exhibited around 2-fold more splicing events than the ERβ- cells. Interestingly, we identified putative direct targets of ERβ-mediated alternative splicing by correlating the genomic locations of ERβ and ERα binding sites with estradiol-induced differential splicing in the corresponding genes.
  
  
  CONCLUSIONS
  Taken together, these results demonstrate that ERβ significantly affects estrogen-induced early transcription and mRNA splicing in hormone-responsive BC cells, providing novel information on the biological role of ERβ in these tumors.
authors.affiliation: Laboratory of Molecular Medicine and Genomics, Department of Medicine and Surgery, University of Salerno, Via S. Allende, 1, Baronissi, SA, 84081, Italy. dgnoel7@gmail.com.|UFR Sciences Biologiques, Université Peleforo Gon Coulibaly, Korhogo, Ivory Coast. dgnoel7@gmail.com.
authors.forename: Dougba Noel
authors.initials: DN
authors.lastname: Dago
authors.affiliation: Department of Molecular and Medical Pharmacology, University of California, Los Angeles, USA. CScafoglio@mednet.ucla.edu.
authors.forename: Claudio
authors.initials: C
authors.lastname: Scafoglio
authors.affiliation: Laboratory of Molecular Medicine and Genomics, Department of Medicine and Surgery, University of Salerno, Via S. Allende, 1, Baronissi, SA, 84081, Italy. arinaldi@unisa.it.
authors.forename: Antonio
authors.initials: A
authors.lastname: Rinaldi
authors.affiliation: Laboratory of Molecular Medicine and Genomics, Department of Medicine and Surgery, University of Salerno, Via S. Allende, 1, Baronissi, SA, 84081, Italy. dmemoli@unisa.it.
authors.forename: Domenico
authors.initials: D
authors.lastname: Memoli
authors.affiliation: Laboratory of Molecular Medicine and Genomics, Department of Medicine and Surgery, University of Salerno, Via S. Allende, 1, Baronissi, SA, 84081, Italy. ggiurato@unisa.it.
authors.forename: Giorgio
authors.initials: G
authors.lastname: Giurato
authors.affiliation: Laboratory of Molecular Medicine and Genomics, Department of Medicine and Surgery, University of Salerno, Via S. Allende, 1, Baronissi, SA, 84081, Italy. gnassa@unisa.it.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Nassa
authors.affiliation: Laboratory of Molecular Medicine and Genomics, Department of Medicine and Surgery, University of Salerno, Via S. Allende, 1, Baronissi, SA, 84081, Italy. mravo@unisa.it.
authors.forename: Maria
authors.initials: M
authors.lastname: Ravo
authors.affiliation: Laboratory of Molecular Medicine and Genomics, Department of Medicine and Surgery, University of Salerno, Via S. Allende, 1, Baronissi, SA, 84081, Italy. frizzo@unisa.it.
authors.forename: Francesca
authors.initials: F
authors.lastname: Rizzo
authors.affiliation: Laboratory of Molecular Medicine and Genomics, Department of Medicine and Surgery, University of Salerno, Via S. Allende, 1, Baronissi, SA, 84081, Italy. rtarallo@unisa.it.
authors.forename: Roberta
authors.initials: R
authors.lastname: Tarallo
authors.affiliation: Laboratory of Molecular Medicine and Genomics, Department of Medicine and Surgery, University of Salerno, Via S. Allende, 1, Baronissi, SA, 84081, Italy. aweisz@unisa.it.|Molecular Pathology and Medical Genomics, "SS. Giovanni di Dio e Ruggi d'Aragona - Schola Medica Salernitana" Hospital of the University of Salerno, Salerno, Italy. aweisz@unisa.it.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Weisz
mesh_terms: D017398:Alternative Splicing / Q000187:drug effects*; D001943:Breast Neoplasms / Q000473:pathology*; D004958:Estradiol / Q000494:pharmacology; D047628:Estrogen Receptor alpha / Q000378:metabolism; D047629:Estrogen Receptor beta / Q000172:deficiency / Q000378:metabolism*; D004967:Estrogens / Q000494:pharmacology*; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D061986:MCF-7 Cells; D011401:Promoter Regions, Genetic / Q000187:drug effects / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D017423:Sequence Analysis, RNA
chemical_list: D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D004967:Estrogens; D012333:RNA, Messenger; D004958:Estradiol