PD-L1 over-expression is driven by B-cell receptor signaling in diffuse large B-cell lymphoma

Area of Science:

• Oncology
• Immunology
• Molecular Biology

Background:

• The programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) pathway is a key target in cancer therapy.
• The biological characteristics of diffuse large B-cell lymphoma (DLBCL) with PD-L1 expression are not well understood.

Purpose of the Study:

• To investigate the correlation between B-cell receptor (BCR) signaling, MYC, and PD-L1 expression in DLBCL.
• To explore the therapeutic potential of targeting the BCR pathway and PD-L1 in DLBCL.

Main Methods:

• Analysis of PD-L1 mRNA and protein levels using RNAscope in situ hybridization and immunohistochemistry in 108 DLBCL cases.
• Investigation of BCR signaling and MYC effects on PD-L1 expression in DLBCL cell lines via qPCR, immunoblotting, and flow cytometry.
• Validation in a xenograft mouse model using ibrutinib.

Main Results:

• pSYK and MYC levels correlated with both PD-L1 mRNA and protein.
• BCR signaling and MYC activation increased PD-L1 expression; BCR inhibition or knockdown reduced PD-L1.
• DLBCL with BCR loss exhibited low PD-L1 levels.
• Ibrutinib treatment downregulated PD-L1 and slowed tumor growth in vivo.

Conclusions:

• DLBCL with PD-L1 expression is characterized by an activated BCR signaling pathway.
• Combined inhibition of BCR and PD-L1 may represent a synergistic therapeutic strategy for DLBCL.