Triptolide reduces PD-L1 through the EGFR and IFN-γ/IRF1 dual signaling pathways

Area of Science:

• Immunology
• Oncology
• Pharmacology

Background:

• Programmed death-ligand 1 (PD-L1) interaction with programmed death 1 (PD-1) promotes cancer cell immune evasion.
• Targeting the PD-1/PD-L1 axis is a key strategy in cancer immunotherapy, but effective small-molecule inhibitors are lacking.
• Non-small cell lung cancer (NSCLC) is a major malignancy where PD-L1 plays a significant role.

Purpose of the Study:

• To investigate the effect of the natural product Triptolide on PD-L1 expression in NSCLC.
• To elucidate the molecular mechanisms underlying Triptolide's action on PD-L1.
• To explore the potential of Triptolide as a therapeutic agent for NSCLC immune checkpoint treatment.

Main Methods:

• Assessing Triptolide's impact on surface PD-L1 expression in NSCLC cells.
• Investigating the role of the EGFR signaling pathway in Triptolide-mediated PD-L1 down-regulation.
• Evaluating the effect of IFN-γ on Triptolide's PD-L1 reduction.
• Analyzing the inhibition of the IFN-γ-JAK-STAT-IRF1 signaling axis by Triptolide, including STAT3 phosphorylation.

Main Results:

• Triptolide significantly down-regulates PD-L1 expression on NSCLC cells.
• This down-regulation is linked to the EGFR signaling pathway.
• IFN-γ partially rescues the Triptolide-induced reduction in PD-L1.
• Triptolide inhibits the IFN-γ-JAK-STAT-IRF1 signaling axis, reducing STAT3 activity.

Conclusions:

• Triptolide reduces PD-L1 expression in NSCLC cells via both EGFR and IFN-γ/JAK/STAT/IRF1 pathways.
• These findings highlight Triptolide's potential application in NSCLC immune checkpoint therapy.
• Triptolide represents a promising small-molecule agent for modulating immune checkpoints in cancer.