title: Hypoxia regulates FGFR3 expression via HIF-1α and miR-100 and contributes to cell survival in non-muscle invasive bladder cancer.
abstract: BACKGROUND
  Non-muscle invasive (NMI) bladder cancer is characterised by increased expression and activating mutations of FGFR3. We have previously investigated the role of microRNAs in bladder cancer and have shown that FGFR3 is a target of miR-100. In this study, we investigated the effects of hypoxia on miR-100 and FGFR3 expression, and the link between miR-100 and FGFR3 in hypoxia.
  
  
  METHODS
  Bladder cancer cell lines were exposed to normoxic or hypoxic conditions and examined for the expression of FGFR3 by quantitative PCR (qPCR) and western blotting, and miR-100 by qPCR. The effect of FGFR3 and miR-100 on cell viability in two-dimensional (2-D) and three-dimensional (3-D) was examined by transfecting siRNA or mimic-100, respectively.
  
  
  RESULTS
  In NMI bladder cancer cell lines, FGFR3 expression was induced by hypoxia in a transcriptional and HIF-1α-dependent manner. Increased FGFR3 was also in part dependent on miR-100 levels, which decreased in hypoxia. Knockdown of FGFR3 led to a decrease in phosphorylation of the downstream kinases mitogen-activated protein kinase (MAPK) and protein kinase B (PKB), which was more pronounced under hypoxic conditions. Furthermore, transfection of mimic-100 also decreased phosphorylation of MAPK and PKB. Finally, knocking down FGFR3 profoundly decreased 2-D and 3-D cell growth, whereas introduction of mimic-100 decreased 3-D growth of cells.
  
  
  CONCLUSIONS
  Hypoxia, in part via suppression of miR-100, induces FGFR3 expression in bladder cancer, both of which have an important role in maintaining cell viability under conditions of stress.
authors.affiliation: Molecular Oncology Laboratories, The Weatherall Institute of Molecular Medicine, The University of Oxford, John Radcliffe Hospital, OX3 9DS Oxford, UK.
authors.forename: C
authors.initials: C
authors.lastname: Blick
authors.forename: A
authors.initials: A
authors.lastname: Ramachandran
authors.forename: S
authors.initials: S
authors.lastname: Wigfield
authors.forename: R
authors.initials: R
authors.lastname: McCormick
authors.forename: A
authors.initials: A
authors.lastname: Jubb
authors.forename: F M
authors.initials: FM
authors.lastname: Buffa
authors.forename: H
authors.initials: H
authors.lastname: Turley
authors.forename: M A
authors.initials: MA
authors.lastname: Knowles
authors.forename: D
authors.initials: D
authors.lastname: Cranston
authors.forename: J
authors.initials: J
authors.lastname: Catto
authors.forename: A L
authors.initials: AL
authors.lastname: Harris
mesh_terms: D015687:Cell Hypoxia / Q000235:genetics*; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D002470:Cell Survival; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000378:metabolism*; D035683:MicroRNAs / Q000378:metabolism*; D009361:Neoplasm Invasiveness; D034622:RNA Interference; D034741:RNA, Small Interfering; D051498:Receptor, Fibroblast Growth Factor, Type 3 / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D001749:Urinary Bladder Neoplasms / Q000378:metabolism* / Q000473:pathology
chemical_list: C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; C544266:MIRN100 microRNA, human; D035683:MicroRNAs; D034741:RNA, Small Interfering; C496365:FGFR3 protein, human; D051498:Receptor, Fibroblast Growth Factor, Type 3