GLUD1 Inhibition Disrupts Glutamate Homeostasis and Induces Metabolic and Redox Stress in Gliomas

Glutamate dehydrogenase (GLUD1) links glutamine metabolism and redox regulation, yet its prognostic and functional relevance across different glioma subtypes warrants further study. Here, we show that GLUD1 expression was inversely associated with tumor grade and positively associated with survival across glioma subtypes, a relationship not fully recapitulated by broader glutaminolysis-related gene signatures. To investigate the consequences of GLUD1 inhibition, we treated endogenous IDH-mutant and IDH-wildtype glioma cell lines with the reported GLUD1 inhibitor R162. GLUD1 inhibition reduced viability in all cell lines tested. This effect was not rescued by α-ketoglutarate (α-KG) supplementation, indicating that impaired tricarboxylic acid (TCA) cycle anaplerosis was not the primary mechanism underlying GLUD1 dependency. Instead, GLUD1 inhibition caused intracellular glutamate accumulation, increased reactive oxygen species (ROS), γ-H2AX induction, and elevated intracellular calcium, while complementary in silico analyses predicted disruption of mitochondrial membrane potential following R162 exposure. Together, these findings indicate that GLUD1 inhibition induces metabolic and redox stress associated with disrupted glutamate and calcium homeostasis and DNA damage. Our findings distinguish the favorable prognostic value of GLUD1 expression from the cellular vulnerability revealed by its inhibition, supporting further investigations of GLUD1 as both a prognostic biomarker and potential therapeutic target in glioma.