ABSTRACT
The mitochondrial enzyme glutaminase C (GAC) is highly expressed in a variety of cancer cells, resulting in increased glutamine metabolism and cancer development. Therefore, GAC has become a potential target for anti-tumor drug development. However, current GAC inhibitors shared similar structural characteristics, few new scaffolds were reported. By conducting a prokaryotic Escherichia coli expression system, human GAC protein of high-purity was obtained through lysozyme digestion combined with ultrasound dissociation, and cobalt magnetic beads purification, Moreover, we performed studies to validate interaction between small molecules and GAC protein through thermal shift assay, drug affinity responsive target stability assay, protein crosslinking and GAC enzyme activity detection. Meanwhile, a comprehensive small molecule-protein interaction confirmation and systematic pharmacodynamic study in vitro were carried out on compound C19, which was a reported GAC inhibitor screened from the Enamine database. Results showed that C19 directly bind to GAC protein, disturbed GAC tetramers formation, and inhibited its enzyme catalytic activity. By interfering GAC function, C19 dose-dependently suppressed GAC-mediated glutamine metabolism, reduced glutamate in cancer cells, and thus alleviated A549 and NCI-H1299 non-small cell lung cancer cell growth. Together, C19 was identified as a lead compound, providing a new strategy for the structural design of drugs targeting GAC.