CD8⁺ T cell activation leads to the rapid proliferation and differentiation of effector T cells (T_effs), which mediate antitumor immunity. Although aerobic glycolysis is preferentially activated in CD8⁺ T_effs, the mechanisms that regulate CD8⁺ T cell glucose uptake in the low-glucose and acidic tumor microenvironment (TME) remain poorly understood. Here, we report that the abundance of the glucose transporter GLUT10 is increased during CD8⁺ T cell activation and antitumor immunity. Specifically, GLUT10 deficiency inhibited glucose uptake, glycolysis, and antitumor efficiency of tumor-infiltrating CD8⁺ T cells. Supplementation with glucose alone was insufficient to rescue the antitumor function and glucose uptake of CD8⁺ T cells in the TME. By analyzing tumor environmental metabolites, we found that high concentrations of lactic acid reduced the glucose uptake, activation, and antitumor effects of CD8⁺ T cells by directly binding to GLUT10's intracellular motif. Disrupting the interaction of lactic acid and GLUT10 by the mimic peptide PG10.3 facilitated CD8⁺ T cell glucose utilization, proliferation, and antitumor functions. The combination of PG10.3 and GLUT1 inhibition or anti-programmed cell death 1 antibody treatment showed synergistic antitumor effects. Together, our data indicate that GLUT10 is selectively required for glucose uptake of CD8⁺ T cells and identify that TME accumulated lactic acid inhibits CD8⁺ T cell effector function by directly binding to GLUT10 and reducing its glucose transport capacity. Last, our study suggests disrupting lactate-GLUT10 binding as a promising therapeutic strategy to enhance CD8⁺ T cell-mediated antitumor effects.

Huimin Jiang

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