Glutamine transporter inhibitor enhances the sensitivity of NSCLC to trametinib through GSDME-dependent pyroptosis

Trametinib, an inhibitor of mitogen-activated extracellular signal-regulated kinases 1/2 (MEK1/2), is used to treat BRAF^V600E/K melanoma and non-small-cell lung cancer (NSCLC). Mutant Kirsten rat sarcoma viral oncogene homolog (KRAS) promotes glutamine utilization, therefore, in the present study we investigated the anti-cancer effects of trametinib in combination with V-9302, a glutamine transporter inhibitor, in NSCLC with KRAS mutations. Trametinib in combination with V-9302 exhibited a potent synergistic antitumor effect, inducing cell cycle arrest and pyroptosis. Mechanistically, combination treatment triggered caspase-3 activation and gasdermin E (GSDME) cleavage, as well as elevated lactate dehydrogenase (LDH) and IL-1β levels. Meanwhile, combination treatment reduced cyclin D1 and p-Rb levels and increased p27 expression. Moreover, this combination increased forkhead box class O3a (FOXO3a) levels and decreased forkhead box M1 (FOXM1) expression by regulating the phosphorylation of ERK, Akt, AMPK, and c-Jun N-terminal kinase (JNK). Trametinib in combination with V-9302 increased reactive oxygen species (ROS) generation and reduced glutathione (GSH) synthesis and ATP levels. Furthermore, V-9302 in combination with trametinib inhibited the trametinib-induced autophagy, thereby enhancing pyroptosis in cancer cells. In vivo, the co-administration of trametinib and V-9302 remarkably inhibited tumor growth in a xenograft mouse model compared to each drug alone. Taken together, the combination of trametinib and V-9302 resulted in increased pyroptosis and cell cycle arrest compared to each single agent through regulation of the FOXO3a/FOXM1 axis and autophagy and significantly enhanced antitumor efficacy in vivo. Our results suggest a potential new therapeutic strategy for KRAS-mutant NSCLC using trametinib in combination with glutamine restriction.