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Biochemical, cellular, and biophysical characterization of a potent inhibitor of mutant isocitrate dehydrogenase IDH1

Davis, MI and Gross, S and Shen, M and Straley, KS and Pragani, R and Lea, WA and Popovici-Muller, J and DeLaBarre, B and Artin, E and Thorne, N and Auld, DS and Li, Z and Dang, L and Boxer, MB and Simeonov, A (2014) Biochemical, cellular, and biophysical characterization of a potent inhibitor of mutant isocitrate dehydrogenase IDH1. Journal of Biological Chemistry, 289 (20). pp. 13717-13725. ISSN 0021-92581083-351X

Abstract

Two mutant forms (R132H and R132C) of isocitrate dehydrogenase 1 (IDH1) have been associated with a number of cancers including glioblastoma and acute myeloid leukemia. These mutations confer a neomorphic activity of 2-hydroxyglutarate (2-HG) production, and 2-HG has previously been implicated as an oncometabolite. Inhibitors of mutant IDH1 can potentially be used to treat these diseases. In this study, we investigated the mechanism of action of a newly discovered inhibitor, ML309, using biochemical, cellular, and biophysical approaches. Substrate binding and product inhibition studies helped to further elucidate the IDH1 R132H catalytic cycle. This rapidly equilibrating inhibitor is active in both biochemical and cellular assays. The (+) isomer is active (IC<sub>50</sub> = 68 nM), whereas the (-) isomer is over 400-fold less active (IC<sub>50</sub> = 29 muM) for IDH1 R132H inhibition. IDH1 R132C was similarly inhibited by (+)- ML309. WT IDH1 was largely unaffected by (+)-ML309 (IC <sub>50</sub> >36 muM). Kinetic analyses combined with microscale thermophoresis and surface plasmon resonance indicate that this reversible inhibitor binds to IDH1 R132H competitively with respect to alpha- ketoglutarate and uncompetitively with respect to NADPH. A reaction scheme for IDH1 R132H inhibition by ML309 is proposed in which ML309 binds to IDH1 R132H after formation of the IDH1 R132H NADPH complex. ML309 was also able to inhibit 2-HG production in a glioblastoma cell line (IC<sub>50</sub>=250 nM) and had minimal cytotoxicity. In the presence of racemic ML309, 2-HG levels drop rapidly. This drop was sustained until 48 h, at which point the compound was washed out and 2-HG levels recovered

Item Type: Article
Additional Information: NIBR author: Auld, DS institute: NIBR- address only contributor address: A. Simeonov, NIH Chemical Genomics Center, National Center for Advancing Translational Sciences, National Institutes of Health, 9800 Medical Center Dr., Rockville, MD 20892, United States. E-mail: asimeono@mail.nih.gov
Date Deposited: 13 Oct 2015 13:12
Last Modified: 04 Jul 2016 23:45
URI: https://oak.novartis.com/id/eprint/22656

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