Stable Isotope-Resolved Metabolomic Differencesbetween Hormone-Responsive and Triple-NegativeBreast Cancer Cell Lines

Purpose. To conduct an exploratory study to identify mechanisms that differentiate Luminal A (BT474 and MCF-7) and triple-negative (MDA-MB-231and MDA-MB-468)breast cancer (BCa) cell lines to potentially provide novel therapeutic targets based ondifferences in energy utilization.Methods. Cells were cultured in media containing either [U-13C]-glucoseor [U-13C]-glutaminefor48 hours. Conditioned media and cellular extracts were analyzed by1Hand13CNMRspectroscopy.Results. MCF-7cells consumedthe most glucose, producing the most lactate, demonstrating the greatest Warburg effect-associated energy utilization. BT474 cellshad the highest tricarboxylic acid cycle (TCA) activity. The majority of energy utilization patterns in MCF-7cells were more similarto MDA-MB-468 cells, while the patterns for BT474 cells were more similar to MDA-MB-231cells. Compared to the Luminal A celllines, TNBC cell lines consumed more glutamine and less glucose. BT474 and MDA-MB-468 cells produced high amounts of13C-glycinefrommedia[U-13C]-glucosewhichwasintegratedintoglutathione,indicatingdenovosynthesis.Conclusions.Stableisotopicresolved metabolomics using13C substrates provided mechanistic information about energy utilization that was difficult to interpretusing1H data alone. Overall, cell lines that have different hormone receptor status have different energy utilization requirements,even if they are classified by the same clinical BCa subtype; and these differences offer clues about optimizing treatment strategies.