Synthesis of Novel Kidney-Type Glutaminase Allosteric Inhibitors Targeting the Critical Lys-320 Residue.

Reversible allosteric inhibitors of kidney-type glutaminase (GLS1, KGA) showed incomplete inhibition of cancer cell proliferation and poor efficacy. Here, we investigate some irreversible inhibitors targeting the critical K320 residue responsible for GLS1 biological activity. The (trifluoromethoxy)phenylacetic acid motif was replaced by α,β-unsaturated carboxylic acids, and the resulting terminally substituted derivatives (e.g., and ) showed good stability in solid form at room temperature, and better liver microsome stability and pharmacokinetics than coumarin. Both compounds showed binding to the wild-type KGA, whose is 10-fold stronger than that of , but only weak binding to the KGA K320A mutant and no inhibition of GDH proteins. Interestingly, treatment significantly decreased the trypsin digestion of KGA, tumor cell clonal formation, and cancer cell growth rate. Taking these results together, targeting the critical K320 residue of GLS1 might be a new strategy to make a potent GLS1 allosteric inhibitor.