Real-time NMR analysis of glutamine metabolism for screening anti-cancer agents in living cells.

Metabolic reprogramming is a substantial obstacle for anticancer drug screening, as targeted therapeutics often lose efficiency due to the dynamic adaption of cancer cells. Glutamine metabolism in cancer profoundly impacts tumor initiation, progression and metastasis. The existing agents are compromised by resistance and off-target toxicity. In this study, a real-time NMR tracking method for intracellular glutamine metabolic flux was established. This method enables comprehensive profiling of nitrogen metabolism and serves as a valuable tool for characterizing specific cancer metabolic phenotypes and screening drugs against targeted cancer cells. Applying this approach to traditional Chinese medicine (TCM) discovery, we identified Astragalus membranaceus as a potent regulator of glutamine metabolism. Through virtual screening via molecular docking, 12 potential compounds from Astragalus membranaceus were initially flagged as candidate binders toward the allosteric pocket of glutaminase 1 (GLS1). Crucially, subsequent in vitro recombinant human GLS1 enzyme activity assays successfully ruled out computational false positives and demonstrated that Compound 2 (quercetin) acts as the exclusive, direct enzymatic inhibitor among the tested monomers, capable of effectively suppressing GLS1 activity. Overall, this work provides a robust platform for real-time metabolic profiling of glutamine metabolism and drug screening at the living cell level, and offers new insights into the mechanisms of TCMs in anticancer therapy.