The glutamine-aspartate metabolic tradeoff between fast growth and metabolic flexibility

Abstract Background Cancer cells develop selective dependencies on nutrients, creating potential opportunities for therapeutic intervention. However, how metabolic rewiring enables cancer cells to sustain proliferation while adapting to nutrient limitation remains incompletely understood. Results We develop a systematic framework to investigate nutrient dependencies and apply it to extracellular glutamine dependence. By measuring metabolite exchange rates across 54 cancer cell lines with different degrees of glutamine dependence, together with metabolic profiling of human stem-cell differentiation, we identify tissue-associated differences in the use of glutamine and aspartate for glutamate biosynthesis. These differences are linked to a trade-off between rapid proliferation and metabolic flexibility. Time-resolved intracellular metabolomics following glutamine withdrawal reveal a common limitation in purine biosynthesis. However, this metabolic limitation alone is insufficient to explain glutamine dependency, suggesting that additional regulatory responses to glutamine deprivation contribute to growth arrest. Conclusions Our study provides a systematic framework for identifying metabolic features associated with nutrient dependence and shows how established functions of glutamine, aspartate and asparagine are coordinated across diverse cancer cell types. This approach may support the mechanistic characterization and pharmacological targeting of metabolic dependencies beyond glutamine addiction.