The hexosamine biosynthetic pathway drives tumor immune evasion via translational control of PD-L1 at the elongation level

Cancer cells reprogram cellular energetics to drive tumorigenesis and escape immunosurveillance. Nevertheless, how this is molecularly connected remains largely undefined. The hexosamine biosynthetic pathway (HBP) serves as a critical metabolic node in cancer cells that provides the basis for protein glycosylation. Herein, we show that HBP flux inhibition by knocking out its rate-limiting enzyme GFAT1 suppressed tumor growth and stimulated cytotoxic CD8⁺ T lymphocyte infiltration in a colorectal cancer model. GFAT1 induced the expression of the immune checkpoint PD-L1 at the translational level by bypassing signal peptide-mediated translation elongation arrest. Proteomic and glycoproteomic screening indicated that GFAT1 facilitated the N-linked glycosylation and protein expression of integrin α2/α3 subunits, leading to FAK activation and elongation factor eEF1A2 upregulation. Pharmacological inhibition of HBP noticeably enhanced the efficacy of immune checkpoint blockade in vivo. Together, these findings unravel how immune checkpoint proteins are manipulated by metabolic dysregulation, which can be exploited as metabolic vulnerability for improving immunotherapies.