Abstract
Glioblastoma (GBM) is the most aggressive primary brain tumor in adults. GBM occurs more commonly in males but female patients survive significantly longer. Understanding the molecular mechanisms underlying this clinical sex disparity could support novel treatment strategies to improve outcomes for GBM patients. In this regard, we found that male and female GBM patient tissues differ in their metabolite profiles and that male GBM exhibit a higher abundance of amino acid metabolites. We confirmed these findings in a murine model of GBM. Furthermore, we found that male GBM cells are more sensitive to amino acid deprivation. This male-specific dependency on amino acids is almost entirely driven by amino acids involved in the synthesis of the antioxidant glutathione. Glutaminase 1 (GLS1) mediates the conversion from glutamine to glutamate, a crucial component of glutathione. We found that male GBM cells are more sensitive to GLS1 inhibition with the clinical inhibitor CB-839. This correlated with significantly increased reactive oxygen species (ROS) in male GBM. We further confirmed sex differences in redox state through pharmacological depletion of glutathione, which resulted in a significant increase in ROS and cell death in male GBM cells. Moreover, assays of glutathione oxidation demonstrated that male GBM cells exist in a chronically oxidized state. Finally, we found that mitochondrial structure and function, including TCA cycle flux, NADH levels, and antioxidant activity, differ between male and female GBM cells. Together, these data suggest that (1) male and female GBM differ in their amino acid requirements, (2) male GBM are more dependent on glutamine to regulate ROS levels, and (3) sex differences in mitochondrial physiology may result in ROS accumulation and increased susceptibility to drugs targeting the redox state in male GBM. Our data reveal novel metabolic targets for GBM and underline the importance of considering sex in metabolic targeting approaches.