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Cancer Metab. 2018 Apr 17;6:4. doi: 10.1186/s40170-018-0177-4. eCollection 2018.

Metabolic characterization of isocitrate dehydrogenase (IDH) mutant and IDH wildtype gliomaspheres uncovers cell type-specific vulnerabilities.

Garrett M#1, Sperry J#2, Braas D2,3, Yan W4, Le TM2,5, Mottahedeh J6, Ludwig K6, Eskin A7, Qin Y6, Levy R8, Breunig JJ8,9,10, Pajonk F11,12, Graeber TG2,3,12, Radu CG2,5,12, Christofk H2,3,12,13, Prins RM1,2,12, Lai A12,14, Liau LM1,12, Coppola G6,14, Kornblum HI2,6,12,13.

Author information

1
1Department of Neurosurgery, and the Interdepartmental Program in the Neurosciences, University of California, Los Angeles, CA 90095 USA.
2
2Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, UCLA, Room 379 Neuroscience Research Building, 635 Charles E. Young Dr. South, Los Angeles, CA 90095 USA.
3
3UCLA Metabolomics Center, UCLA, Los Angeles, USA.
4
4Department of Chemistry and Biochemistry, UCLA, Los Angeles, USA.
5
5Ahmanson Translational Imaging Division, UCLA, Los Angeles, USA.
6
6Department of Psychiatry and Biobehavioral Sciences and Semel Institute for Neuroscience & Human Behavior, UCLA, Room 379 Neuroscience Research Building, 635 Charles E. Young Dr. South, Los Angeles, CA 90095 USA.
7
7Department of Human Genetics, UCLA, Los Angeles, USA.
8
8Board of Governors Regenerative Medicine Institute, Cedars-Sinai Medical Center, Los Angeles, CA USA.
9
9Samuel Oschin Comprehensive Cancer Center, Cedars-Sinai Medical Center, Los Angeles, CA USA.
10
10Department of Biomedical Sciences, Cedars-Sinai Medical Center, Los Angeles, CA USA.
11
11Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, USA.
12
12Jonsson Comprehensive Cancer Center, UCLA, Room 379 Neuroscience Research Building, 635 Charles E. Young Dr. South, Los Angeles, CA 90095 USA.
13
14Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research, UCLA, Room 379 Neuroscience Research Building, 635 Charles E. Young Dr. South, Los Angeles, CA 90095 USA.
14
13Department of Neurology, UCLA, Los Angeles, USA.
#
Contributed equally

Abstract

Background:

There is considerable interest in defining the metabolic abnormalities of IDH mutant tumors to exploit for therapy. While most studies have attempted to discern function by using cell lines transduced with exogenous IDH mutant enzyme, in this study, we perform unbiased metabolomics to discover metabolic differences between a cohort of patient-derived IDH1 mutant and IDH wildtype gliomaspheres.

Methods:

Using both our own microarray and the TCGA datasets, we performed KEGG analysis to define pathways differentially enriched in IDH1 mutant and IDH wildtype cells and tumors. Liquid chromatography coupled to mass spectrometry analysis with labeled glucose and deoxycytidine tracers was used to determine differences in overall cellular metabolism and nucleotide synthesis. Radiation-induced DNA damage and repair capacity was assessed using a comet assay. Differences between endogenous IDH1 mutant metabolism and that of IDH wildtype cells transduced with the IDH1 (R132H) mutation were also investigated.

Results:

Our KEGG analysis revealed that IDH wildtype cells were enriched for pathways involved in de novo nucleotide synthesis, while IDH1 mutant cells were enriched for pathways involved in DNA repair. LC-MS analysis with fully labeled 13C-glucose revealed distinct labeling patterns between IDH1 mutant and wildtype cells. Additional LC-MS tracing experiments confirmed increased de novo nucleotide synthesis in IDH wildtype cells relative to IDH1 mutant cells. Endogenous IDH1 mutant cultures incurred less DNA damage than IDH wildtype cultures and sustained better overall growth following X-ray radiation. Overexpression of mutant IDH1 in a wildtype line did not reproduce the range of metabolic differences observed in lines expressing endogenous mutations, but resulted in depletion of glutamine and TCA cycle intermediates, an increase in DNA damage following radiation, and a rise in intracellular ROS.

Conclusions:

These results demonstrate that IDH1 mutant and IDH wildtype cells are easily distinguishable metabolically by analyzing expression profiles and glucose consumption. Our results also highlight important differences in nucleotide synthesis utilization and DNA repair capacity that could be exploited for therapy. Altogether, this study demonstrates that IDH1 mutant gliomas are a distinct subclass of glioma with a less malignant, but also therapy-resistant, metabolic profile that will likely require distinct modes of therapy.

KEYWORDS:

2-hydroxyglutarate; Glioma; Metabolism; Nucleotide; Radiation

Conflict of interest statement

All patient samples were collected under UCLA Institutional Review Board-approved protocols (Protocol ID: IRB# 11–000432).Not applicable.The authors declare that they have no competing interests.Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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