Browsing by Subject "Glutarates"

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    Disruption of wild-type IDH1 suppresses D-2-hydroxyglutarate production in IDH1-mutated gliomas.
    (Cancer research, 2013-01) Jin, Genglin; Reitman, Zachary J; Duncan, Christopher G; Spasojevic, Ivan; Gooden, David M; Rasheed, B Ahmed; Yang, Rui; Lopez, Giselle Y; He, Yiping; McLendon, Roger E; Bigner, Darell D; Yan, Hai
    Point mutations at Arg132 of the cytoplasmic NADP(+)-dependent isocitrate dehydrogenase 1 (IDH1) occur frequently in gliomas and result in a gain of function to produce the "oncometabolite" D-2-hydroxyglutarate (D-2HG). The mutated IDH1 allele is usually associated with a wild-type IDH1 allele (heterozygous) in cancer. Here, we identify 2 gliomas that underwent loss of the wild-type IDH1 allele but retained the mutant IDH1 allele following tumor progression from World Health Organization (WHO) grade III anaplastic astrocytomas to WHO grade IV glioblastomas. Intratumoral D-2HG was 14-fold lower in the glioblastomas lacking wild-type IDH1 than in glioblastomas with heterozygous IDH1 mutations. To characterize the contribution of wild-type IDH1 to cancer cell D-2HG production, we established an IDH1-mutated astrocytoma (IMA) cell line from a WHO grade III anaplastic astrocytoma. Disruption of the wild-type IDH1 allele in IMA cells by gene targeting resulted in an 87-fold decrease in cellular D-2HG levels, showing that both wild-type and mutant IDH1 alleles are required for D-2HG production in glioma cells. Expression of wild-type IDH1 was also critical for mutant IDH1-associated D-2HG production in the colorectal cancer cell line HCT116. These insights may aid in the development of therapeutic strategies to target IDH1-mutated cancers.
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    ItemOpen Access
    Transformation by the (R)-enantiomer of 2-hydroxyglutarate linked to EGLN activation.
    (Nature, 2012-02-15) Koivunen, Peppi; Lee, Sungwoo; Duncan, Christopher G; Lopez, Giselle; Lu, Gang; Ramkissoon, Shakti; Losman, Julie A; Joensuu, Päivi; Bergmann, Ulrich; Gross, Stefan; Travins, Jeremy; Weiss, Samuel; Looper, Ryan; Ligon, Keith L; Verhaak, Roel GW; Yan, Hai; Kaelin, William G
    The identification of succinate dehydrogenase (SDH), fumarate hydratase (FH) and isocitrate dehydrogenase (IDH) mutations in human cancers has rekindled the idea that altered cellular metabolism can transform cells. Inactivating SDH and FH mutations cause the accumulation of succinate and fumarate, respectively, which can inhibit 2-oxoglutarate (2-OG)-dependent enzymes, including the EGLN prolyl 4-hydroxylases that mark the hypoxia inducible factor (HIF) transcription factor for polyubiquitylation and proteasomal degradation. Inappropriate HIF activation is suspected of contributing to the pathogenesis of SDH-defective and FH-defective tumours but can suppress tumour growth in some other contexts. IDH1 and IDH2, which catalyse the interconversion of isocitrate and 2-OG, are frequently mutated in human brain tumours and leukaemias. The resulting mutants have the neomorphic ability to convert 2-OG to the (R)-enantiomer of 2-hydroxyglutarate ((R)-2HG). Here we show that (R)-2HG, but not (S)-2HG, stimulates EGLN activity, leading to diminished HIF levels, which enhances the proliferation and soft agar growth of human astrocytes. These findings define an enantiomer-specific mechanism by which the (R)-2HG that accumulates in IDH mutant brain tumours promotes transformation and provide a justification for exploring EGLN inhibition as a potential treatment strategy.