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-¹³C]-glucose or [U-¹³C]-glutamine for 48 hours. Conditioned media and cellular extracts were analyzed by ¹H and ¹³C 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 ¹³C-glycine from media [U-¹³C]-glucose which was integrated into glutathione, indicating de novo synthesis.

Conclusions: Stable isotopic resolved metabolomics using ¹³C substrates provided mechanistic information about energy utilization that was difficult to interpret using ¹H 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.