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

Abstract

Reversible allosteric inhibitors of kidney-type glutaminase (GLS1, KGA) showed incomplete inhibition of cancer cell proliferation and poor in vivo 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 CB839 derivatives (e.g., GJ2 and GJ5) showed good stability in solid form at room temperature, and better liver microsome stability and in vivo pharmacokinetics than coumarin. Both compounds showed binding to the wild-type KGA, whose K D is 10 6 -fold stronger than that of CB839, but only weak binding to the KGA K320A mutant and no inhibition of GDH proteins. Interestingly, GJ2 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.

Targeting the Subpocket Enables the Discovery of Thiadiazole–Pyridazine Derivatives as Glutaminase C Inhibitors

“…13−15 The first GAC covalent inhibitor, GJ2 (8), was also recently reported. 16 Our goal in this article was to develop GAC inhibitors with high potency and antitumor activity. On the basis of the analysis of published GAC X-ray crystal structures, a novel subpocket comprising basic amino acids Arg317 and Lys320 was discovered.…”

“…Currently, 4 is a promising GAC inhibitor in phase II clinical trials. Many other allosteric GAC inhibitors have been reported in recent years, such as IPN60090 ( 5 ) with a triazole structure, 6a obtained through structural simplification, and macrocyclic GAC inhibitor LL202 ( 7 ). − The first GAC covalent inhibitor, GJ2 ( 8 ), was also recently reported …”