Stable Isotope-Resolved Metabolomic Differences between Hormone-Responsive and Triple-Negative Breast 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-231 and MDA-MB-468) breast cancer (BCa) cell lines to potentially provide novel therapeutic targets based on differences in energy utilization. METHODS: Cells were cultured in media containing either [U-(13)C]-glucose or [U-(13)C]-glutamine for 48 hours. Conditioned media and cellular extracts were analyzed by (1)H and (13)C NMR spectroscopy. RESULTS: MCF-7 cells consumed the most glucose, producing the most lactate, demonstrating the greatest Warburg effect-associated energy utilization. BT474 cells had the highest tricarboxylic acid cycle (TCA) activity. The majority of energy utilization patterns in MCF-7 cells were more similar to MDA-MB-468 cells, while the patterns for BT474 cells were more similar to MDA-MB-231 cells. Compared to the Luminal A cell lines, TNBC cell lines consumed more glutamine and less glucose. BT474 and MDA-MB-468 cells produced high amounts of (13)C-glycine from media [U-(13)C]-glucose which was integrated into glutathione, indicating de novo synthesis. CONCLUSIONS: Stable isotopic resolved metabolomics using (13)C substrates provided mechanistic information about energy utilization that was difficult to interpret using (1)H 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.