Serine-Driven Metabolic Plasticity Drives Adaptive Resilience in Pancreatic Cancer Cells [PANC-1]

Pancreatic cancer is one of the most lethal malignancies, partly due to its profound metabolic adaptability, which contributes to drug resistance and therapeutic failure. Understanding how pancreatic cancer cells reprogram their metabolism in response to treatment may uncover new therapeutic vulnerabilities. This study investigates the metabolic adaptations underlying resistance to drug treatment in pancreatic cancer using a systems metabolomics approach to explore novel biomarkers and therapeutic strategies. Methods: Eight human pancreatic cancer cell lines were analyzed to assess metabolic heterogeneity and drug response. Untargeted and isotope-labeled metabolomics were performed to evaluate metabolic rewiring before and after treatment with erastin, a redox-disrupting agent. Differential correlation analysis was applied to identify key metabolic nodes associated with treatment adaptation. Combinatorial treatments using FDA-approved drugs targeting glycolysis and one-carbon metabolism were tested. Multi-omics integration of metabolomics and transcriptomics data was conducted to elucidate mechanisms of resistance. Results: Pancreatic cancer cell lines exhibited marked metabolic heterogeneity, with differences in nutrient dependency and mitochondrial activity. Erastin treatment revealed metabolic vulnerabilities but failed to sustain long-term growth suppression. Combinatorial treatments of erastin with methotrexate or alpelisib significantly reduced proliferation and induced metabolic alteration. A systems-level analysis identified serine metabolism as a central adaptive pathway activated in resistant mechanism. Metabolic tracing and gene expression analyses revealed increased de novo serine biosynthesis and uptake, coupled with enhanced redox balancing and epigenetic regulation. Notably, cell lines that reactivated growth after drug withdrawal exhibited transcriptional reprogramming involving serine-driven pathways. These adaptations were associated with increased expression of survival, proliferation and migration-related genes. Conclusions: This study demonstrates that pancreatic cancer cells rewire their metabolism in response to combinatorial drug treatment by activating serine synthesis and uptake. These metabolic adaptations sustain redox homeostasis, biosynthetic processes and transcriptional reprogramming, contributing to resistance mechanism. Serine metabolism emerges as a functional biomarker of metabolic plasticity and drug tolerance. These insights open new avenues for metabolism-based strategies to overcome resistance and advance precision therapy in pancreatic cancer. Drug treatment induced gene expression was measured after 72 hours of multi-stage treatment. 8 independent experiments for wash-out control and 7 independent experiments for re-combinatorial treatment were conducted.