Papillary thyroid carcinoma shows elevated levels of 2-hydroxyglutarate.
ABSTRACT Elevated levels of D: -2-hydroxyglutarate (D: -2-HG) occur in gliomas and myeloid leukemias associated with mutations of IDH1 and IDH2. L: -2-Hydroxyglutaric aciduria, an inherited metabolic disorder, predisposes to brain tumors. Therefore, we asked whether sporadic cancers, without IDH1 or IDH2 hot-spot mutations, show elevated 2-hydroxyglutarate levels. We retrieved 15 pairs of frozen papillary thyroid carcinoma (PTC) and adjacent non-neoplastic thyroid, and 14 pairs of hyperplastic nodule (HN) and adjacent non-hyperplastic thyroid. In all lesions, exon 4 sequencing confirmed the absence of known mutations of IDH1 and IDH2. We measured 2-hydroxyglutarate by liquid chromatography-tandem mass spectrometry. Compared to normal thyroid, PTCs had significantly higher D: -2-HG and L: -2-hydroxyglutarate (L: -2-HG) levels, and compared to HNs, PTCs had significantly higher D: -2-HG levels. D: -2-HG/L: -2-HG levels were not significantly different between HNs and normal thyroid. Further studies should clarify if elevated 2-hydroxyglutarate in PTC may be useful as cancer biomarker and evaluate the role of 2-hydroxyglutarate in cancer biology.
SourceAvailable from: Arindam P Ghosh[Show abstract] [Hide abstract]
ABSTRACT: Through unbiased metabolomics, we identified elevations of the metabolite 2-hydroxyglutarate (2HG) in renal cell carcinoma (RCC). 2HG can inhibit 2-oxoglutaratre (2-OG) dependent dioxygenases which mediate epigenetic events including DNA and histone demethylation. 2HG accumulation, specifically the D- enantiomer, can result from gain of function mutations of isocitrate dehydrogenase (IDH1, IDH2) found in several different tumors. In contrast, kidney tumors demonstrate elevations of the L enantiomer of 2HG (L-2HG). High 2HG tumors demonstrate reduced DNA levels of 5-hydroxymethylcytosine (5hmC) consistent with 2-HG mediated inhibition of TET (Ten Eleven Translocation) enzymes which convert 5-methylcystoine (5mC) to 5hmC. L-2HG elevation is mediated in part by reduced expression of L-2HG dehydrogenase (L2HGDH). L2HGDH reconstitution in RCC cells lowers L-2HG and promotes 5hmC accumulation. Additionally, L2HGDH expression in RCC cells reduces histone methylation and suppresses in vitro tumor phenotypes. Our report identifies L-2HG as an epigenetic modifier and putative oncometabolite in kidney cancer.Cancer Discovery 09/2014; 4(11). DOI:10.1158/2159-8290.CD-13-0696 · 15.93 Impact Factor
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ABSTRACT: Abstract Citrate is an important substrate in cellular energy metabolism. It is produced in mitochondria and used in the Krebs cycle or released into cytoplasm through a specific mitochondrial carrier, CIC. In the cytosol citrate and its derivatives, acetyl-CoA and oxaloacetate, are used in normal and pathological processes. Beyond the classical role as metabolic regulator, recent studies have highlighted that citrate is involved in inflammation, cancer, insulin secretion, histone acetylation, neurological disorders and NAFLD (Non-alcoholic fatty liver disease). Monitoring changes in the citrate levels could therefore potentially be used as diagnostic tool. This review highlights these new aspects of citrate functions.Biological Chemistry 01/2014; 395(4). DOI:10.1515/hsz-2013-0271 · 2.69 Impact Factor
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ABSTRACT: Mammalian cells generate citrate by decarboxylating pyruvate in the mitochondria to supply the tricarboxylic acid (TCA) cycle. In contrast, hypoxia and other impairments of mitochondrial function induce an alternative pathway that produces citrate by reductively carboxylating α-ketoglutarate (AKG) via NADPH-dependent isocitrate dehydrogenase (IDH). It is unknown how cells generate reducing equivalents necessary to supply reductive carboxylation in the setting of mitochondrial impairment. Here, we identified shared metabolic features in cells using reductive carboxylation. Paradoxically, reductive carboxylation was accompanied by concomitant AKG oxidation in the TCA cycle. Inhibiting AKG oxidation decreased reducing equivalent availability and suppressed reductive carboxylation. Interrupting transfer of reducing equivalents from NADH to NADPH by nicotinamide nucleotide transhydrogenase increased NADH abundance and decreased NADPH abundance while suppressing reductive carboxylation. The data demonstrate that reductive carboxylation requires bidirectional AKG metabolism along oxidative and reductive pathways, with the oxidative pathway producing reducing equivalents used to operate IDH in reverse.Cell Reports 05/2014; 7(5). DOI:10.1016/j.celrep.2014.04.037 · 7.21 Impact Factor