title: Mutations in CIC and IDH1 cooperatively regulate 2-hydroxyglutarate levels and cell clonogenicity.
abstract: The majority of oligodendrogliomas (ODGs) exhibit combined losses of chromosomes 1p and 19q and mutations of isocitrate dehydrogenase (IDH1-R132H or IDH2-R172K). Approximately 70% of ODGs with 1p19q co-deletions harbor somatic mutations in the Capicua Transcriptional Repressor (CIC) gene on chromosome 19q13.2. Here we show that endogenous long (CIC-L) and short (CIC-S) CIC proteins are predominantly localized to the nucleus or cytoplasm, respectively. Cytoplasmic CIC-S is found in close proximity to the mitochondria. To study wild type and mutant CIC function and motivated by the paucity of 1p19q co-deleted ODG lines, we created HEK293 and HOG stable cell lines ectopically co-expressing CIC and IDH1. Non-mutant lines displayed increased clonogenicity, but cells co-expressing the mutant IDH1-R132H with either CIC-S-R201W or -R1515H showed reduced clonogenicity in an additive manner, demonstrating cooperative effects in our assays. Expression of mutant CIC-R1515H increased cellular 2-Hydroxyglutarate (2HG) levels compared to wild type CIC in IDH1-R132H background. Levels of phosphorylated ATP-citrate Lyase (ACLY) were lower in cell lines expressing mutant CIC-S proteins compared to cells expressing wild type CIC-S, supporting a cytosolic citrate metabolism-related mechanism bof reduced clonogenicity in our in vitro model systems. ACLY or phospho-ACLY were similarly reduced in CIC-mutant 1p19q co-deleted oligodendroglioma patient samples.
authors.affiliation: Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC, Canada.
authors.forename: Suganthi
authors.initials: S
authors.lastname: Chittaranjan
authors.affiliation: Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC, Canada.
authors.forename: Susanna
authors.initials: S
authors.lastname: Chan
authors.affiliation: Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC, Canada.
authors.forename: Cindy
authors.initials: C
authors.lastname: Yang
authors.affiliation: Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC, Canada.
authors.forename: Kevin C
authors.initials: KC
authors.lastname: Yang
authors.affiliation: Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC, Canada.
authors.forename: Vincent
authors.initials: V
authors.lastname: Chen
authors.affiliation: Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC, Canada. California Institute of Technology, Beckman Institute, Pasadena, CA, USA.
authors.forename: Annie
authors.initials: A
authors.lastname: Moradian
authors.affiliation: Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC, Canada.
authors.forename: Marlo
authors.initials: M
authors.lastname: Firme
authors.affiliation: Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC, Canada.
authors.forename: Jungeun
authors.initials: J
authors.lastname: Song
authors.affiliation: Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC, Canada. Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada.
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Go
authors.affiliation: Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada. Southern Alberta Cancer Research Institute, University of Calgary, Calgary, AB, Canada. Clark H. Smith Brain Tumour Centre, University of Calgary, Calgary, AB, Canada.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Blough
authors.affiliation: Southern Alberta Cancer Research Institute, University of Calgary, Calgary, AB, Canada. Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, AB, Canada. Clark H. Smith Brain Tumour Centre, University of Calgary, Calgary, AB, Canada.
authors.forename: Jennifer A
authors.initials: JA
authors.lastname: Chan
authors.affiliation: Department of Clinical Neurosciences, University of Calgary, Calgary, AB, Canada. Southern Alberta Cancer Research Institute, University of Calgary, Calgary, AB, Canada. Clark H. Smith Brain Tumour Centre, University of Calgary, Calgary, AB, Canada.
authors.forename: J Gregory
authors.initials: JG
authors.lastname: Cairncross
authors.affiliation: Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC, Canada. Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC, Canada.
authors.forename: Sharon M
authors.initials: SM
authors.lastname: Gorski
authors.affiliation: Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC, Canada. Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Gregg B
authors.initials: GB
authors.lastname: Morin
authors.affiliation: Department of Pathology and Laboratory Medicine Vancouver General Hospital, Vancouver, BC, Canada.
authors.forename: Stephen
authors.initials: S
authors.lastname: Yip
authors.affiliation: Canada's Michael Smith Genome Sciences Centre, BC Cancer Agency, Vancouver, BC, Canada. Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Marco A
authors.initials: MA
authors.lastname: Marra
mesh_terms: D015153:Blotting, Western; D001932:Brain Neoplasms / Q000235:genetics* / Q000378:metabolism; D045744:Cell Line, Tumor; D005977:Glutarates / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D007521:Isocitrate Dehydrogenase / Q000235:genetics*; D013058:Mass Spectrometry; D009154:Mutation; D009837:Oligodendroglioma / Q000235:genetics* / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics*
chemical_list: C498610:CIC protein, human; D005977:Glutarates; D012097:Repressor Proteins; C019417:alpha-hydroxyglutarate; D007521:Isocitrate Dehydrogenase; C543588:IDH1 protein, human