Abstract 2216 Does Cytosolic Malate Dehydrogenase (hMDH1) Have a Sinister Role in Tumor Cell Survival? Could Phosphorylation Transform hMDH1 from a Mild-Mannered Metabolic Enzyme to a Supporter of Cancer Cell Progression

Malate dehydrogenase (EC 1.1.1.37) is an enzyme involved in cellular metabolism that catalyzes the reversible oxidation of malate to oxaloacetate using the reduction of nicotinamide adenine dinucleotide (NAD+/NADH). Human cytosolic, malate dehydrogenase splice variant 3 (hMDH1V3) is encoded by MDH-1 gene. In acidic conditions where tumor cells undergo a high rate of glycolysis, hMDH1V3 can at low rates produce the oncometabolite 2-hydroxyglutarate (2HG) from α-Ketoglutarate (αKG). Several mass-spectroscopy databases have identified more than 25 phosphorylation sites of hMDH1.