Study on endogenous inhibitors against PD-L1: cAMP as a potential candidate

Area of Science:

• Biochemistry
• Immunology
• Computational Biology

Background:

• The programmed cell death protein 1 (PD-1)/programmed cell death-ligand 1 (PD-L1) pathway is a critical target for novel anti-cancer drug development.
• Identifying endogenous compounds that modulate this pathway is crucial for understanding immune regulation in cancer.

Purpose of the Study:

• To screen endogenous compounds for their ability to inhibit the PD-1/PD-L1 interaction.
• To investigate the mechanism by which cyclic adenosine monophosphate (cAMP) affects PD-1/PD-L1 binding and cancer cell behavior.

Main Methods:

• Biological affinity ultrafiltration (BAU) for compound screening.
• UPLC-HRMS for compound identification.
• Molecular dynamic (MD) simulations and molecular docking for interaction analysis.
• Homogeneous time-resolved fluorescence (HTRF) and Förster resonance energy transfer (FRET) assays for in vitro validation.

Main Results:

• Cyclic adenosine monophosphate (cAMP) was identified as a direct inhibitor of PD-1/PD-L1 binding, with an IC50 of 36.4 ± 9.3 μM.
• cAMP demonstrated the ability to restore Jurkat T cell proliferation and potentially suppress PD-L1 expression on DU-145 cells.
• FRET assays and computational methods confirmed cAMP binds to PD-L1 and induces its dimerization.

Conclusions:

• cAMP is a novel endogenous inhibitor targeting the PD-1/PD-L1 interaction.
• These findings offer new insights into the role of endogenous molecules in regulating PD-L1 activity.
• cAMP presents a potential therapeutic lead for developing new anti-cancer treatments targeting the PD-1/PD-L1 pathway.