Diterpenoid tanshinones enhance CD8+ T-cell-mediated antitumor immunity in gastric cancer by suppressing ENO1 activity and glycolysis

Background Salvia miltiorrhiza Bunge contains bioactive tanshinones with antitumor activity, but whether diterpenoid tanshinones (DT) suppress gastric cancer by coupling glycolytic inhibition to CD8 + T-cell responses remains unclear. This study investigated the antitumor effects of DT and the contribution of the ENO1-lactate axis to tumor immune regulation. Materials and Methods DT composition was characterized by ultra-performance liquid chromatography-high-resolution mass spectrometry. Antitumor activity was evaluated in a subcutaneous syngeneic MFC gastric cancer model in 615 mice, including CD8 + T-cell depletion and lactate-challenge experiments. Tumor-infiltrating immune cells were analyzed by flow cytometry, immunohistochemistry, and multiplex immunofluorescence. In gastric cancer cells, lactate production and extracellular acidification were measured using colorimetric and Seahorse assays. Network pharmacology, drug affinity responsive target stability, and cellular thermal shift assays were used to identify and assess candidate targets, followed by western blotting and enzyme-activity assays. Results DT suppressed tumor growth and increased intratumoral CD8 + T-cell infiltration, whereas CD8 + T-cell depletion attenuated its antitumor effect. DT reduced lactate production and glycolytic activity in gastric cancer cells and tumors. DARTS and CETSA supported target engagement between DT and ENO1. DT reduced ENO1 enzymatic activity and phosphoenolpyruvate levels without markedly changing ENO1 protein abundance. Exogenous lactate promoted tumor growth, while acidic culture conditions reduced CD8 + T-cell viability. Compared with the model group, DT alone increased the percentages of CD8 + and GZMB + cells and decreased the percentage of PD-1+ cells in tumor tissue. Conclusion DT restrains gastric tumor growth through an immunometabolic mechanism involving ENO1 inhibition, reduced glycolytic lactate production, and antitumor activity involving CD8 + T cells. These findings support further preclinical evaluation of DT and the ENO1-lactate axis in gastric cancer.