Mevalonate Biosynthesis is a Metabolic Vulnerability of Gemcitabine-resistant Pancreatic Cancer
Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy with a devastating prognosis. Gemcitabine, a pyrimidine anti-metabolite, is a cornerstone in PDAC therapy. However, resistance remains a major hurdle in clinical care. Resistance can arise from microenvironmental metabolites or through direct metabolic reprogramming of pancreatic cancer cells. Here, we generated PDAC models of acquired gemcitabine resistance to determine the relationship between these mechanisms. We observed that physiological levels of exogenous pyrimidines have a diminished ability to impact gemcitabine response in PDAC cells with acquired resistance. This occurs as the metabolic reprogramming of PDAC cells in response to gemcitabine treatment forces a suppression of the pyrimidine salvage pathway. Importantly, this metabolic rewiring renders gemcitabine-resistant PDAC cells highly susceptible to inhibition of the rate limiting enzyme of the mevalonate biosynthesis pathway, 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), using statins. Notably, statin treatment inhibits the growth of gemcitabine-resistant tumors in immunocompetent mouse models. Through metabolite rescue experiments, we identified geranylgeranyl pyrophosphate as the critical metabolite lost during statin treatment, resulting in reduced protein geranylation in PDAC cells. Finally, as downregulation of the HMGCR is gradually acquired during gemcitabine resistance, we observed that HMGCR expression predicts patient response to gemcitabine. Collectively, these data demonstrate that the mevalonate biosynthesis pathway represents a promising therapeutic target in gemcitabine resistance and may serve as a biomarker to stratify treatment selection in PDAC patients.