Premium
Understanding the Impact of IDH2 Mutations on the Redox Balance of Cancer Cells
Author(s) -
Gelman Susan J.,
McKenzie Lisa,
Chheda Milan G.,
Patti Gary J.
Publication year - 2018
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2018.32.1_supplement.811.13
Subject(s) - idh2 , isocitrate dehydrogenase , chemistry , idh1 , cytosol , biochemistry , pentose phosphate pathway , mutant , enzyme , glycolysis , gene
Study Objective We seek to answer the following question: how does consumption of NADPH by mutant IDH2 for 2‐HG synthesis affect other NADPH‐dependent pathways in the mitochondria? Methods HCT116 IDH2 mutants were incubated in the presence of H 2 O 2 or irradiated with 3,6, or 9 Gy ionizing radiation (IR) and cell viability was assessed with a trypan blue exclusion assay. Stable isotope tracing was performed by incubating HCT116 cells (n=3) with the specified isotope for 12–24 hours, then harvested in ice‐cold methanol. After extracting metabolites from cells in a mixture of methanol, acetonitrile, and water, samples were run on a Thermo QExactive Plus using liquid chromatography/mass spectrometry (LC/MS) with a HILIC column in negative mode. Results and Conclusion Isocitrate dehydrogenase 2 (IDH2) mutants are found in cases of acute myeloid leukemia (AML), glioblastoma, chondrosarcoma, and lymphoma cancers. IDH2 is one of two nicotinamide adenine dinucleotide (NADPH)‐dependent isoforms of IDH. While IDH1 is found exclusively in the cytosol, IDH2 is localized to the mitochondria. Both enzymes are mutated in cancer to produce 2‐hydroxyglutarate (2‐HG) in millimolar amounts. The neomorphic reaction consumes the essential redox factor NADPH. Previous research indicates that IDH1 mutants are dependent upon upregulation of the pentose phosphate pathway (PPP) to supply more NADPH for 2‐HG synthesis. However, this pathway is localized to the cytosol and NADPH is not capable of crossing the mitochondrial membrane to supply the IDH2 reaction. To study the effects of NADPH consumption/production with respect to compartmentalization, we used stable isotope labeling and LC/MS to assess central carbon pathway flux in comparison to IDH1 and WT cells. Our preliminary data suggests that IDH2 mutants may be dependent on compensatory mechanisms to generate essential metabolic factors (such as ME1 and the folate cycle). We conclude that IDH2 mutations lead to metabolic rewiring of the TCA cycle to support the demand of 2‐HG synthesis in the mitochondria. Support or Funding Information GJP received financial support for this work from the National Institutes of Health Grants R35ES028365 and R21CA191097 as well as the Alfred P. Sloan Foundation, the Pew Scholars Program in the Biomedical Sciences, and the Edward Mallinckrodt, Jr Foundation. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .