Next generation thiazolyl ketone inhibitors of cytosolic phospholipase A α for targeted cancer therapy.

Eicosanoids are key players in inflammatory diseases and cancer. Targeting their production by inhibiting Group IVA cytosolic phospholipase A (cPLAα) offers a promising approach for cancer therapy. In this study, we synthesize a second generation of thiazolyl ketone inhibitors of cPLAα starting with compound GK470 (AVX235) and test their in vitro and cellular activities. We identify a more potent and selective lead molecule, GK420 (AVX420), which we test in parallel with AVX235 and a structurally unrelated compound, AVX002 for inhibition of cell viability across a panel of cancer cell lines. From this, we show that activity of polycomb group repressive complex 2 is a key molecular determinant of sensitivity to cPLAα inhibition, while resistance depends on antioxidant response pathways. Consistent with these results, we show that elevated intracellular reactive oxygen species and activating transcription factor 4 target gene expression precede cell death in AVX420-sensitive T-cell acute lymphoblastic leukemia cells. Our findings imply cPLAα may support cancer by mitigating oxidative stress and inhibiting tumor suppressor expression and suggest that AVX420 has potential for treating acute leukemias and other cancers that are susceptible to oxidative cell death.