Redox, lipid, and metabolic changes associated with early tolerance to combination chemotherapy in two pancreatic cancer cell models

Abstract Pancreatic ductal adenocarcinoma (PDAC) shows limited responsiveness to chemotherapy and rapidly develops resistance, which can be facilitated by early adaptive tolerance to sub-lethal drug exposure. Here, we investigated changes associated with the development of early tolerance to a chemotherapy combination analogous in composition to FOLFIRINOX in MIA PaCa-2 and PANC-1 cells using a stepwise adaptation approach. Comparison of metabolic similarities and divergences between the two cell lines by dose-response analysis revealed limited, yet progressive and cell-specific, shiftsin drug sensitivity. At the consolidated stage, Nile Red imaging and targeted lipidomics revealed cell line-specific lipid remodeling, including elongation of membrane phospholipid acyl chains in both lines. PANC-1 cells show increased saturation of phosphatidylcholine and triacylglycerols and reduced polyunsaturation of phosphatidylethanolamine and phosphatidylcholine. Antioxidant profiling also shows model-dependent patterns: MIA PaCa-2 cells exhibit increased total catalase, total glutathione S-transferase, and glutathione reductase activities, whereas PANC-1 cells show reduced catalase activity together with increased total glutathione S-transferase activity. These changes are accompanied by increased cytosolic and mitochondrial oxidation-dependent fluorescence in MIA PaCa-2 cells and reduced mitochondrial oxidation-dependent fluorescence in PANC-1 cells. MIA PaCa-2 cells also showed reduced extracellular lactate production, while cellular energy charge remained unchanged in both models. Whether these adaptations can be exploited therapeutically remains to be tested; they nevertheless identify redox- and lipid-related pathways as candidates for functional studies aimed at preventing the transition from tolerance to stable resistance.