Specific inhibition by synthetic analogs of pyruvate reveals that the pyruvate dehydrogenase reaction is essential for metabolism and viability of glioblastoma cells
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Victoria I. Bunik1,2, Artem Artiukhov2, Alexey Kazantsev3, Renata Goncalves4, Danilo Daloso5, Henry Oppermann6, Elena Kulakovskaya7, Nikolay Lukashev3, Alisdair Fernie5, Martin Brand4, Frank Gaunitz6
1A.N. Belozersky Institute of Physicochemical Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
2Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119234 Moscow, Russia
3Faculty of Chemistry, Lomonosov Moscow State University, 119234 Moscow, Russia
4Buck Institute for Research on Aging, Novato, CA 94945, USA
5Max-Planck-Institute of Molecular Plant Physiology, 14476 Potsdam-Golm, Germany
6Department of Neurosurgery, Medical Faculty of the University of Leipzig, 04103 Leipzig, Germany
7Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
Victoria I. Bunik, e-mail: firstname.lastname@example.org
Keywords: pyruvate dehydrogenase, pyruvate synthetic analog, acetyl phosphinate, acetyl phosphonate, glioblastoma viability
Received: June 19, 2015 Accepted: October 02, 2015 Published: October 15, 2015
The pyruvate dehydrogenase complex (PDHC) and its phosphorylation are considered essential for oncotransformation, but it is unclear whether cancer cells require PDHC to be functional or silenced. We used specific inhibition of PDHC by synthetic structural analogs of pyruvate to resolve this question. With isolated and intramitochondrial PDHC, acetyl phosphinate (AcPH, KiAcPH = 0.1 μM) was a much more potent competitive inhibitor than the methyl ester of acetyl phosphonate (AcPMe, KiAcPMe = 40 μM). When preincubated with the complex, AcPH also irreversibly inactivated PDHC. Pyruvate prevented, but did not reverse the inactivation. The pyruvate analogs did not significantly inhibit other 2-oxo acid dehydrogenases. Different cell lines were exposed to the inhibitors and a membrane-permeable precursor of AcPMe, dimethyl acetyl phosphonate, which did not inhibit isolated PDHC. Using an ATP-based assay, dependence of cellular viability on the concentration of the pyruvate analogs was followed. The highest toxicity of the membrane-permeable precursor suggested that the cellular action of charged AcPH and AcPMe requires monocarboxylate transporters. The relevant cell-specific transcripts extracted from Gene Expression Omnibus database indicated that cell lines with higher expression of monocarboxylate transporters and PDHC components were more sensitive to the PDHC inhibitors. Prior to a detectable antiproliferative action, AcPH significantly changed metabolic profiles of the investigated glioblastoma cell lines. We conclude that catalytic transformation of pyruvate by pyruvate dehydrogenase is essential for the metabolism and viability of glioblastoma cell lines, although metabolic heterogeneity causes different cellular sensitivities and/or abilities to cope with PDHC inhibition.
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