IDH1 R132C Research Articles

Isocitrate Dehydrogenase (IDH) Mutations Promote a Reversible ZEB1/MicroRNA (miR)-200-dependent Epithelial-Mesenchymal Transition (EMT)

Mutations in the genes encoding isocitrate dehydrogenase 1 and 2 (IDH1/2) occur in a variety of tumor types, resulting in production of the proposed oncometabolite, 2-hydroxyglutarate (2-HG). How mutant IDH and 2-HG alter signaling pathways to promote cancer, however, remains unclear. Additionally, there exist relatively few cell lines with IDH mutations. To examine the effect of endogenous IDH mutations and 2-HG, we created a panel of isogenic epithelial cell lines with either wild-type IDH1/2 or clinically relevant IDH1/2 mutations. Differences were noted in the ability of IDH mutations to cause robust 2-HG accumulation. IDH1/2 mutants that produce high levels of 2-HG cause an epithelial-mesenchymal transition (EMT)-like phenotype, characterized by changes in EMT-related gene expression and cellular morphology. 2-HG is sufficient to recapitulate aspects of this phenotype in the absence of an IDH mutation. In the cells types examined, mutant IDH-induced EMT is dependent on up-regulation of the transcription factor ZEB1 and down-regulation of the miR-200 family of microRNAs. Furthermore, sustained knockdown of IDH1 in IDH1 R132H mutant cells is sufficient to reverse many characteristics of EMT, demonstrating that continued expression of mutant IDH is required to maintain this phenotype. These results suggest mutant IDH proteins can reversibly deregulate discrete signaling pathways that contribute to tumorigenesis.

Type and location of isocitrate dehydrogenase mutations influence clinical characteristics and disease outcome of acute myeloid leukemia

Mutations of isocitrate dehydrogenase 1 and 2 (IDH1/2) are genetic alterations in acute myeloid leukemia (AML). The aim of our study was to investigate the frequency and prognostic effect of IDH1/2 mutations together followed by an individual analysis of each substitution in a Hungarian cohort consisting of 376 patients with AML. IDH1mut and IDH2mut were mutually exclusive, detected in 8.5% and 7.5% of cases, respectively. IDH1/2mut was associated with: older age (p = 0.001), higher average platelet count (p = 0.001), intermediate karyotype (p < 0.0001), NPM1mut (p = 0.022) and lower mRNA expression level of ABCG2 gene (p = 0.006). Overall survival (OS), remission and relapse rates were not different in IDH1mut or IDH2mut vs. IDHneg. IDH1mut and IDH2mut were associated differently with NPM1mut; co-occurrence was observed in 14.3% of IDH1 R132C vs. 70% of R132H carriers (p = 0.02) and in 47.4% of IDH2 R140Q vs. 0% of R172K carriers (p = 0.02). IDH1 R132H negatively influenced OS compared to IDHneg (p = 0.02) or R132C (p = 0.019). Particular amino acid changes affecting the same IDH1 codon influence the clinical characteristics and treatment outcome in AML.

Three new chondrosarcoma cell lines: one grade III conventional central chondrosarcoma and two dedifferentiated chondrosarcomas of bone

BackgroundChondrosarcoma is the second most common primary sarcoma of bone. High-grade conventional chondrosarcoma and dedifferentiated chondrosarcoma have a poor outcome. In pre-clinical research aiming at the identification of novel treatment targets, the need for representative cell lines and model systems is high, but availability is scarce.MethodsWe developed and characterized three cell lines, derived from conventional grade III chondrosarcoma (L835), and dedifferentiated chondrosarcoma (L2975 and L3252) of bone. Proliferation and migration were studied and we used COBRA-FISH and array-CGH for karyotyping and genotyping. Immunohistochemistry for p16 and p53 was performed as well as TP53 and IDH mutation analysis. Cells were injected into nude mice to establish their tumorigenic potential.ResultsWe show that the three cell lines have distinct migrative properties, L2975 had the highest migration rate and showed tumorigenic potential in mice. All cell lines showed chromosomal rearrangements with complex karyotypes and genotypic aberrations were conserved throughout late passaging of the cell lines. All cell lines showed loss of CDKN2A, while TP53 was wild type for exons 5–8. L835 has an IDH1 R132C mutation, L2975 an IDH2 R172W mutation and L3252 is IDH wild type.ConclusionsBased on the stable culturing properties of these cell lines and their genotypic profile resembling the original tumors, these cell lines should provide useful functional models to further characterize chondrosarcoma and to evaluate new treatment strategies.

Frequent IDH1/2 mutations in intracranial chondrosarcoma: a possible diagnostic clue for its differentiation from chordoma

Mutations in the genes encoding isocitrate dehydrogenase (IDH) 1/2 have been detected in a significant proportion of diffuse gliomas and in a small fraction of acute myeloid leukemia (AML) cases. Recently, in an examination of various types of mesenchymal tumor, IDH1/2 mutations were only found in cartilaginous tumors including central conventional and periosteal enchondromas/chondrosarcomas. The frequency of IDH1/2 mutations was 56%, and the IDH1 R132C mutation, which is not common in diffuse gliomas or AML, accounted for 40% of these mutations. In this study, we investigated the IDH1/2 mutation status of intracranial chondrosarcomas and chordomas, which are morphologically similar and affect similar regions of the cranial cavity. Of the 13 chondrosarcomas analyzed, six (46.1%) displayed IDH1/2 mutations (the predominant type was IDH1 R132C). Also, an IDH2 mutation (R172S) was observed in one case. Conversely, none of the ten chordomas analyzed displayed any IDH1 or IDH2 mutations. Our data suggest that the IDH1/2 mutation status could be valuable for distinguishing intracranial chondrosarcomas from chordomas.

IDH mutation status in prostate cancer

In a recent Oncogene review, Yen et al. summarized the important role of somatic mutations in the cytoplasmic and mitochondrial forms of isocitrate dehydrogenase (IDH1 and IDH2, respectively) in cancer. These gliomaand acute myeloid leukemia-associated mutations occur at IDH1 codon 132 (that is, R132) or in IDH2, at codon 172 or 140 (that is, R172, R140). Although cancer-associated IDH1/2 mutations impair the wild-type IDH activity of the enzymes, they activate a novel enzymatic function in converting aketoglutarate to 2-hydroxyglutarate, which leads to DNA hypermethylation and increased angiogenesis through stabilization of hypoxia-inducible transcription factor-1a. Yen et al. highlighted the value of documenting mutant IDH1 and IDH2 enzymes as targets for individualized and novel cancer therapies. We have determined IDH1/2 mutations in localized prostate cancer (PCa), which has significant heterogeneity in genomic stability, tumor metabolism and clinical outcome. Mutational and array comparative genomic hybridization analyses for R132, R172 or R140 mutations as well as IDH1/2 allelic copy number were conducted in 158 PCa DNA samples following IRB consent, as previously described. IDH1 and IDH2 mutations were determined using a Sequenom MassARRAY platform and confirmed by direct Sanger sequencing. Our analysis revealed an IDH1 R132C mutation in one patient (T1cN0M0, Gleason score 6; prostate-specific antigen 4.8 ng/ml) and an IDH1 R132H mutation in a second patient (T2aN0M0, Gleason score 7; prostate-specific antigen 33 ng/ml). No IDH2 mutations were detected (Table 1). Our study population also was assessed for allelic loss at 10q (PTEN), 8P (NKX3.1), 17p (p53) and gain at 8q21 (c-MYC). However, these genetic alterations neither uniquely associate with IDH mutation nor with allelic gain/loss of IDH1/2 (found in four other patients; see Supplementary Table 1). Mutation or allelic loss of IDH1/2 is therefore rare in localized PCa, based on our large series and previous data (Table 1). However, in the era of personalized medicine, the 2% of patients with mutated IDH1 PCa could be considered for future mutant IDH-targeted therapy and possibly prevent the need for local therapies with side effects (for example, radiotherapy or surgery). Given the role of hypoxia and altered metabolism in PCa heterogeneity and prognosis, further research is warranted on mutations that may alter PCa hypoxia and/or metabolism, which could lead to novel and personalized therapy in subgroups of localized PCa patients.

Abstract 5452: Cancer-associated metabolite 2-hydroxyglutarate accumulates in AML with IDH1/2 mutations

Abstract Mutations in isocitrate dehydrogenase 1 and 2 (IDH1/2), are present in most gliomas and secondary glioblastomas, but are rare in other neoplasms. IDH1/2 mutations are heterozygous, and affect a single arginine residue. Recently, IDH1 mutations were identified in 8% of acute myelogenous leukemia (AML) patients. Our previous study revealed that IDH1 mutations cause a gain of function, resulting in the production and accumulation of 2-hydroxyglutarate (2-HG). Genotyping of 145 AML biopsies identified 11 IDH1 R132 mutant samples. Liquid chromatography-mass spectrometry metabolite screening revealed increased 2-HG levels in IDH1 R132 mutant cells and sera, and uncovered two IDH2 R172K mutations. IDH1/2 mutations were associated with normal karyotypes. Recombinant IDH1 R132C and IDH2 R172K proteins catalyze the novel NADPH -dependent reduction of alpha-ketoglutarate (a-KG) to 2-HG. The IDH1 R132C mutation commonly found in AML reduces the affinity for isocitrate, and increases the affinity for NADPH and a-KG. This prevents the oxidative decarboxylation of isocitrate to a-KG, and facilitates the conversion of a-KG to 2-HG. IDH1/2 mutations confer an enzymatic gain of function that dramatically increases 2-HG in AML. This provides an explanation for the heterozygous acquisition of these mutations during tumorigenesis. 2-HG is a tractable metabolic biomarker of mutant IDH1/2 enzyme activity. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5452.

Cancer-associated metabolite 2-hydroxyglutarate accumulates in acute myelogenous leukemia with isocitrate dehydrogenase 1 and 2 mutations

Mutations in isocitrate dehydrogenase 1 and 2 (IDH1/2), are present in most gliomas and secondary glioblastomas, but are rare in other neoplasms. IDH1/2 mutations are heterozygous, and affect a single arginine residue. Recently, IDH1 mutations were identified in 8% of acute myelogenous leukemia (AML) patients. A glioma study revealed that IDH1 mutations cause a gain-of-function, resulting in the production and accumulation of 2-hydroxyglutarate (2-HG). Genotyping of 145 AML biopsies identified 11 IDH1 R132 mutant samples. Liquid chromatography-mass spectrometry metabolite screening revealed increased 2-HG levels in IDH1 R132 mutant cells and sera, and uncovered two IDH2 R172K mutations. IDH1/2 mutations were associated with normal karyotypes. Recombinant IDH1 R132C and IDH2 R172K proteins catalyze the novel nicotinamide adenine dinucleotide phosphate (NADPH)–dependent reduction of α-ketoglutarate (α-KG) to 2-HG. The IDH1 R132C mutation commonly found in AML reduces the affinity for isocitrate, and increases the affinity for NADPH and α-KG. This prevents the oxidative decarboxylation of isocitrate to α-KG, and facilitates the conversion of α-KG to 2-HG. IDH1/2 mutations confer an enzymatic gain of function that dramatically increases 2-HG in AML. This provides an explanation for the heterozygous acquisition of these mutations during tumorigenesis. 2-HG is a tractable metabolic biomarker of mutant IDH1/2 enzyme activity.

Selective acquisition of IDH1 R132C mutations in astrocytomas associated with Li-Fraumeni syndrome

Mutations of the IDH1 gene are frequent in gliomas, with R132H (CGT-->CAT) being the most common (>85%). In astrocytomas, IDH1 mutations are typically co-present with, or precede, TP53 mutations. We assessed IDH1 mutations in brain tumors diagnosed in patients from three families with Li-Fraumeni syndrome. We identified IDH1 mutations in five astrocytomas that developed in carriers of a TP53 germline mutation. Without exception, all were R132C (CGT-->TGT), which in sporadic astrocytomas accounts for <5% of IDH1 mutations. This remarkably selective occurrence of R132C mutations may reflect differences in the sequence of genetic events, with a preference for R132C mutations in astrocytes or precursor cells that already carry a germline TP53 mutation.