Endosomal sorting regulates PD-L1 trafficking and enhances immunotherapy efficacy

ABSTRACT: Immune-checkpoint inhibition affecting the PD-1/PD-L1 pathway is a robust clinical approach to treat cancer. Unfortunately, antibody-binding-caused PD-L1 internalization and recycling can lead to resistance and reduced clinical efficacy. Inhibiting lysosome-mediated PD-L1 degradation is necessary to preserve the PD-L1 level that recycles back to the cell membrane. It remains unclear whether there exists a specific mechanism that regulates the trafficking of PD-L1 into endosomes or lysosomes. We identified transmembrane-9 superfamily members 1-4 (TM9SF1-4) through a targeted CRISPR screen, with TM9SF2 emerging as a critical regulator. Mechanistically, TM9SF2 interacts with phosphoglycerate kinase 1 (PGK1), facilitating the endosomal recycling of PD-L1 back to the plasma membrane. Simultaneously, this interaction complex inhibits the pathway of lysosomal PD-L1 degradation via eliminating lysosome carrier HIP1R. Genetic or chemical inhibition of TM9SF2 or PGK1 reduced PD-L1 levels, enhancing the efficacy of immunotherapy. Furthermore, metabolomics-guided screening revealed that treatment with Cer(d18:1/26:0) or the overexpression of its synthase CERS3 disrupted the TM9SF2-PGK1 complex, shifting the process from endosomal recycling to lysosomal degradation. This transition led to a reduction in PD-L1 expression and increased immune responses in murine tumors. Our findings establish the TM9SF2-PGK1 complex as a signaling hub responsive to ceramide, regulating PD-L1 sorting in the endosomal system and contributing to cancer immune evasion. These insights highlight potential therapeutic strategies to augment immune responses by controlling PD-L1 trafficking.

INSTRUMENT(S):

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Cell Culture

SUBMITTER: Fan Yang  

LAB HEAD: Wei Zhao

PROVIDER: PXD061780 | Pride | 2026-06-08

REPOSITORIES: Pride