GPT2 mediates glutamine metabolism-driven metabolic alterations in platinum-resistant ovarian cancer cells

Metabolic reprogramming is recognized as a hallmark of cancer frequently associated with drug resistance in ovarian cancer. This is problematic as ovarian cancer is one of the deadliest gynecologic cancers with platinum resistance contributing to poor survival. However, the mechanism by which ovarian cancer cell metabolism contributes to platinum resistance is not well understood. Herein, metabolic signatures were determined in platinum-resistant ovarian cancer cell lines compared to the more platinum-sensitive parental lines. Chemoresistant ovarian cancer cells showed increased oxidative phosphorylation (OXPHOS) compared to chemosensitive cells. This was associated with elevated levels of glutaminolysis and tricarboxylic acid (TCA)-related metabolites supporting their dependence on OXPHOS. Key enzymes involved in glutaminolysis, specifically, glutamic-pyruvic transaminase 2 (GPT2), were upregulated in chemoresistant compared to chemosensitive cells. Interestingly, high GPT2 gene expression is associated with worse prognosis in ovarian cancer patients, adding translational relevance to the pre-clinical findings. GPT2 knockout in chemoresistant cells restored the metabolic phenotype to that of the sensitive cells and reversed drug resistance. These data suggest that GPT2 is a critical link between glutaminolysis, the TCA cycle, and OXPHOS and is a potential target to attenuate the increased metabolic activity associated with a chemoresistant phenotype.