Oncogenic isocitrate dehydrogenase mutations: Mechanisms, models, and clinical opportunities

Abstract

Heterozygous mutations in catalytic arginine residues of isocitrate dehydrogenases 1 and 2 (IDH1 and IDH2) are common in glioma, acute myeloid leukemia, chondrosarcoma, cholangiocarcinoma, and angioimmunoblastic T-cell lymphoma. The mutant enzymes acquire a neomorphic activity that converts α-ketoglutarate (α-KG) to D-2-hydroxyglutarate (D2HG), a rare metabolite. In cells and tissues expressing mutant IDH, D2HG concentrations are highly elevated. D2HG may act as an "oncometabolite" by inhibiting a class of α-KG-dependent enzymes involved in epigenetic regulation, collagen synthesis, and cell signaling. Knock-in mouse models of IDH1 mutations have shed light on these mechanisms and will provide valuable animal models for further investigation. Significance: Mutations in IDH1 and IDH2 promote the development of a number of malignancies. These active site mutations cause a gain-of-function leading to the accumulation of the rare metabolite D2HG. Mouse models of these mutations should provide insights into the mechanisms driving tumorigenesis and facilitate evaluation of new treatments. © 2013 American Association for Cancer Research.