Synergistic dual targeting of mTOR and GLS1 overcomes glutamine-driven resistance in triple-negative breast cancer.

Resistance to therapeutic agents represents a critical barrier in the clinical management of triple-negative breast cancer (TNBC), necessitating novel therapeutic strategies. We discovered that mammalian target of rapamycin (mTOR) and glutaminase 1 (GLS1) mediated glutamine metabolism-a TNBC-addicted process-critically drives aggressive proliferation and confers therapeutic resistance. The combined treatment with rapamycin (an mTOR inhibitor) and CB839 (a GLS1 inhibitor) elicited synergistic anti-tumor effects in diverse TNBC cell lines. This synergy arose from‌ inhibition of metabolic rewiring, ‌characterized by‌ perturbations in adenosine triphosphate (ATP) homeostasis, redox equilibrium, metabolite pools, and signaling cascades, ‌ultimately triggering multimodal‌ cell death mechanisms. Furthermore, ‌synergistic‌ pharmacological inhibition of mTOR and GLS1 ‌significantly suppressed‌ in vivo tumor growth and metastasis ‌in murine models‌, ‌with no overt toxic effects observed‌. Overall, our findings indicate dual inhibition of mTOR and GLS1 as a promising clinical strategy to counteract glutamine-driven resistance, enhancing therapeutic efficacy in TNBC.