Eradication of Triple-Negative Breast Cancer Cells by Targeting Glycosylated PD-L1

Area of Science:

• Immunology
• Cancer Biology
• Glycobiology

Background:

• Protein glycosylation impacts protein function and immune responses.
• The role of glycosylation in immune suppression, particularly in cancer, is not fully understood.
• Programmed death ligand 1 (PD-L1) and programmed cell death protein 1 (PD-1) are key immune checkpoint proteins.

Purpose of the Study:

• To investigate the role of protein glycosylation in immune suppression.
• To explore the potential of targeting glycosylated PD-L1 (gPD-L1) for cancer therapy.

Main Methods:

• Studied the effect of EGF on PD-L1 and PD-1 interaction in triple-negative breast cancer.
• Investigated the role of β-1,3-N-acetylglucosaminyl transferase (B3GNT3) in PD-L1 glycosylation.
• Developed and tested a monoclonal antibody targeting gPD-L1.

Main Results:

• EGF-induced PD-L1/PD-1 interaction requires B3GNT3 expression.
• Downregulation of B3GNT3 enhances T cell-mediated anti-tumor immunity.
• A gPD-L1 antibody blocked PD-L1/PD-1 interaction, promoted PD-L1 degradation, and induced potent anti-tumor effects, including bystander killing, with no detectable toxicity.

Conclusions:

• Targeting protein glycosylation is a promising strategy to enhance immune checkpoint therapy.
• gPD-L1 antibodies can overcome immune suppression and directly kill cancer cells.
• This approach offers a novel therapeutic avenue for triple-negative breast cancer and potentially other malignancies.