Abstract 5378: GLUD1 protects NSCLC from glucose starvation through a novel enzyme-independent function

Abstract Lung cancer is the leading cause of cancer-related deaths among both men and women in the United States with non-small cell lung cancer (NSCLC) accounting for 85% of all lung cancers. However, regardless of genetic background, nearly all NSCLC are dependent on upregulation of glutamine metabolism for survival, and consequently, the nonessential amino acid glutamine becomes conditionally essential to many tumors. Tumor cells generate the bulk of their ATP by upregulating glycolysis and discarding of the majority of glycolytic carbon as lactate, known as the Warburg effect. This lost carbon is replaced by glutamine-dependent anaplerosis of the mitochondrial tricarboxylic acid (TCA) cycle, which maintains a pool of biosynthetic intermediates that contribute to cell growth. Glutaminolysis is also crucial for the regulation of cell proliferation, survival, and chemoresistance by supporting NADPH and GSH synthesis, regulating of redox metabolism, preventing apoptosis, activating of autophagy, as well as influencing oncogenic signalings such as mTOR, Ras, NRF2 and Hippo pathway. Glutamate dehydrogenase 1 (GLUD1) is an enzyme in the glutaminolysis pathway that catalyzes the reversible conversion of glutamate to alpha-ketoglutarate (aKG). GLUD1 acts as an energy sensor and undergoes a high degree of allosteric and post-translational regulation. GLUD1 also seems to play a direct role in the regulation of multiple cell signaling pathways including mTORC1 activation, signals through glutathione peroxidase 1 (GPX1) to regulate redox homeostasis, directly activates p38 MAPK signaling, and activates CamKK2-AMPKa1 signaling to prevent anoikis and promote metastasis. Our data shows knockout of GLUD1 sensitizes cancer cells to nutrient starvation, but expression of enzymatically dead GLUD1 mutants R443S or R463A still protect cancer cells from glucose starvation-induced cell death. We observe a rapid drop in ATP coupled with the loss of AMPK activation in GLUD1 KO cells under glucose starvation. Cell death can be rescued with the direct AMPK activator A769662 or exacerbated by the AMPK inhibitor Dorsomorphin. Inhibition of cysteine import with xCT-inhibiting compounds Erastin and Sulfasalazine, knockdown of xCT, or cysteine/glucose double starvation also rescues cell death. Novel post-translational modifications to GLUD1 were identified by mass spec including acetylation, methylation, and a previously unknown phosphorylation site. In addition, BioID protein proximity labeling identified several new potential interactors for GLUD1 including kinases and glycolysis proteins. We propose the GLUD1 protein possesses a previously undiscovered function that activates AMPK signaling, thereby inhibiting cysteine import and protecting against cell death under glucose starvation. Citation Format: Ryan Clay, Lingtao Jin. GLUD1 protects NSCLC from glucose starvation through a novel enzyme-independent function [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 5378.