Metabolic reprogramming in cancer cells can increase their dependence on metabolic substrates such as glucose. As such, the vulnerability of cancer cells to glucose deprivation creates an attractive opportunity for therapeutic intervention. Because it is not possible to starve tumors of glucose in vivo, here we sought to identify the mechanisms in glucose deprivation–induced cancer cell death and then designed inhibitor combinations to mimic glucose deprivation–induced cell death. Using metabolomic profiling, we found that cells undergoing glucose deprivation–induced cell death exhibited dramatic accumulation of intracellular l-cysteine and its oxidized dimer, l-cystine, and depletion of the antioxidant GSH. Building on this observation, we show that glucose deprivation–induced cell death is driven not by the lack of glucose, but rather by l-cystine import. Following glucose deprivation, the import of l-cystine and its subsequent reduction to l-cysteine depleted both NADPH and GSH pools, thereby allowing toxic accumulation of reactive oxygen species. Consistent with this model, we found that the glutamate/cystine antiporter (xCT) is required for increased sensitivity to glucose deprivation. We searched for glycolytic enzymes whose expression is essential for the survival of cancer cells with high xCT expression and identified glucose transporter type 1 (GLUT1). Testing a drug combination that co-targeted GLUT1 and GSH synthesis, we found that this combination induces synthetic lethal cell death in high xCT-expressing cell lines susceptible to glucose deprivation. These results indicate that co-targeting GLUT1 and GSH synthesis may offer a potential therapeutic approach for targeting tumors dependent on glucose for survival.

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The consequences of metabolic reprogramming in cancer can include an increased dependence on metabolic substrates such as glucose for survival. As such, the vulnerability of cancer cells to glucose deprivation creates an attractive opportunity for therapeutic intervention. Because it is not possible to starve tumors of glucose in vivo, we sought to identify the mechanisms regulating cancer cell death upon glucose deprivation and then design combinations of inhibitors to mimic glucose deprivation-induced cell death. Using metabolomic profiling, we found that cells undergoing glucose deprivationinduced cell death exhibited dramatic accumulation of intracellular L-cysteine and its oxidized dimer, L-cystine, and depletion of the antioxidant glutathione. Building on this observation, we show that glucose deprivation-induced cell death is driven not by lack of glucose but rather by L-cystine import. Following glucose deprivation, the import of Lcystine and subsequent reduction to L-cysteine depleted both NADPH and glutathione, thereby allowing toxic accumulation of reactive oxygen species. Consistent with this model, we found that the glutamate/cystine antiporter, xCT, was required for sensitivity to glucose deprivation. We searched for glycolytic enzymes whose expression is essential for survival of cancer cells with high xCT expression and identified the glucose transporter GLUT1. We therefore tested a drug combination co-targeting GLUT1 and glutathione synthesis and found that these drugs induced synthetic lethal cell death in high xCTexpressing cell lines susceptible to glucose deprivation. These results indicate that cotargeting GLUT1 and glutathione synthesis is a potential therapeutic approach in tumors dependent on glucose for survival. L-cystine drives glucose deprivation-induced cell deathIntroduction: