Glutaminase and poly

Many cancer-associated mutations that deregulate cellular metabolic responses to hypoxia also reprogram carbon metabolism to promote utilization of glutamine. In renal cell carcinoma (RCC), cells deficient in the von Hippel-Lindau (VHL) tumor suppressor gene use glutamine to generate citrate and lipids through reductive carboxylation (RC) of [alpha]-ketoglutarate ([alpha]/KG). Glutamine can also generate aspartate, the carbon source for pyrimidine biosynthesis, and glutathione for redox balance. Here we have shown that [VHL.sup.-/-] RCC cells rely on RC-derived aspartate to maintain de novo pyrimidine biosynthesis. Glutaminase 1 (GLS1) inhibitors depleted pyrimidines and increased ROS in [VHL.sup.-/-] cells but not in [VHL.sup.+/+] cells, which utilized glucose oxidation for glutamate and aspartate production. GLS1 inhibitor-induced nucleoside depletion and ROS enhancement led to DNA replication stress and activation of an intra-S phase checkpoint, and suppressed the growth of [VHL.sup.-/-] RCC cells. These effects were rescued by administration of glutamate, [alpha]KG, or nucleobases with N-acetylcysteine. Further, we observed that the poly(ADP-ribose) polymerase (PARP) inhibitor olaparib synergizes with GLS1 inhibitors to suppress the growth of [VHL.sup.-/-] cells in vitro and in vivo. This work describes a mechanism that explains the sensitivity of RCC tumor growth to GLS1 inhibitors and supports the development of therapeutic strategies for targeting VHL-deficient RCC.