[Regulation of PD-L1 posttranslational modification and its application progress in tumor immunotherapy]

The immune checkpoint, programmed death 1 ligand-1/programmed death -1 (PD-L1/PD-1), is one of the most promising targets for tumor immunotherapy. Overexpressed PD-L1 on the surface of tumor cells could bind to PD-1 on the surface of T cells and inhibit the T cell activation, triggering tumor-immune-escape; therapeutic strategies targeting PD-1/PD-L1 restore the cytotoxic function of immune cells in the tumors by blocking PD-1/PD-L1 interaction. The PD-L1 undergoes multi-level regulations in tumor cells. Among them, post-translational modifications (PTMs) of PD-L1 mainly including glycosylation, phosphorylation, ubiquitination, acetylation and palmitoylation, have attracted much attention in recent years. These modifications directly affect the stability, cellular localization and function of PD-L1, and subsequently regulate the T cell activation and tumor immunity. Therefore, intervention with PTMs of PD-L1 may serve as a new approach for anti-tumor immunity-escape therapy.