High-Content Screening of Eukaryotic Kinase Inhibitors Identify CHK2 Inhibitor Activity Against Mycobacterium tuberculosis

Abstract

A screen of a eukaryotic kinase inhibitor library in an established intracellular infection model identified a set of drug candidates enabling intracellular killing of <i>Mycobacterium tuberculosis</i> (<i>M.tb</i>). Screen validity was confirmed internally by a <i>Z</i>' = 0.5 and externally by detecting previously reported host-targeting anti-<i>M.tb</i> compounds. Inhibitors of the CHK kinase family, specifically checkpoint kinase 2 (CHK2), showed the highest inhibition and lowest toxicity of all kinase families. The screen identified and validated DDUG, a CHK2 inhibitor, as a novel bactericidal anti-<i>M.tb</i> compound. CHK2 inhibition by RNAi phenocopied the intracellular inhibitory effect of DDUG. DDUG was active intracellularly against <i>M.tb</i>, but not other mycobacteria. DDUG also had extracellular activity against 4 of 12 bacteria tested, including <i>M.tb</i>. Combined, these observations suggest DDUG acts in tandem against both host and pathogen. Importantly, DDUG's validation highlights the screening and analysis methodology developed for this screen, which identified novel host-directed anti-<i>M.tb</i> compounds.