title: Identification of a hypoxia-regulated miRNA signature in bladder cancer and a role for miR-145 in hypoxia-dependent apoptosis.
abstract: BACKGROUND
  Hypoxia leads to the stabilisation of the hypoxia-inducible factor (HIF) transcription factor that drives the expression of target genes including microRNAs (miRNAs). MicroRNAs are known to regulate many genes involved in tumourigenesis. The aim of this study was to identify hypoxia-regulated miRNAs (HRMs) in bladder cancer and investigate their functional significance.
  
  
  METHODS
  Bladder cancer cell lines were exposed to normoxic and hypoxic conditions and interrogated for the expression of 384 miRNAs by qPCR. Functional studies were carried out using siRNA-mediated gene knockdown and chromatin immunoprecipitations. Apoptosis was quantified by annexin V staining and flow cytometry.
  
  
  RESULTS
  The HRM signature for NMI bladder cancer lines includes miR-210, miR-193b, miR-145, miR-125-3p, miR-708 and miR-517a. The most hypoxia-upregulated miRNA was miR-145. The miR-145 was a direct target of HIF-1α and two hypoxia response elements were identified within the promoter region of the gene. Finally, the hypoxic upregulation of miR-145 contributed to increased apoptosis in RT4 cells.
  
  
  CONCLUSIONS
  We have demonstrated the hypoxic regulation of a number of miRNAs in bladder cancer. We have shown that miR-145 is a novel, robust and direct HIF target gene that in turn leads to increased cell death in NMI bladder cancer cell lines.
authors.affiliation: 1] Molecular Oncology Laboratories, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK [2] Department of Urology, Churchill Hospital, Oxford OX3 7LE, UK.
authors.forename: C
authors.initials: C
authors.lastname: Blick
authors.affiliation: 1] Molecular Oncology Laboratories, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK [2] Cancer Research UK London Research Institute, Lincoln's Inn Fields Laboratories, London WC2A 3LY, UK.
authors.forename: A
authors.initials: A
authors.lastname: Ramachandran
authors.affiliation: Molecular Oncology Laboratories, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK.
authors.forename: R
authors.initials: R
authors.lastname: McCormick
authors.affiliation: Molecular Oncology Laboratories, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK.
authors.forename: S
authors.initials: S
authors.lastname: Wigfield
authors.affiliation: Department of Urology, Churchill Hospital, Oxford OX3 7LE, UK.
authors.forename: D
authors.initials: D
authors.lastname: Cranston
authors.affiliation: The Academic Department of Urology and Institute for Cancer Studies, University of Sheffield, Sheffield S10 2RX, UK.
authors.forename: J
authors.initials: J
authors.lastname: Catto
authors.affiliation: Molecular Oncology Laboratories, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford OX3 9DS, UK.
authors.forename: A L
authors.initials: AL
authors.lastname: Harris
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics*; D045744:Cell Line, Tumor; D000860:Hypoxia / Q000235:genetics* / Q000473:pathology; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics; D035683:MicroRNAs / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics; D001749:Urinary Bladder Neoplasms / Q000235:genetics* / Q000473:pathology*
chemical_list: D051795:Hypoxia-Inducible Factor 1, alpha Subunit; C541010:MIRN145 microRNA, human; D035683:MicroRNAs; D034741:RNA, Small Interfering