PD-L1 expression is mainly regulated by interferon gamma associated with JAK-STAT pathway in gastric cancer

Area of Science:

• Oncology
• Immunology
• Cancer Biology

Background:

• Advanced gastric cancer has a poor prognosis despite current treatments.
• Novel therapeutic strategies, including immunotherapy with anti-programmed death-1/ligand-1 monoclonal antibodies (mAbs), are needed.
• Understanding programmed death-ligand 1 (PD-L1) upregulation in the tumor microenvironment is crucial for effective immunotherapy.

Purpose of the Study:

• To investigate the mechanisms regulating PD-L1 expression in gastric cancer.
• To examine the role of interferon gamma (IFN-γ) in PD-L1 upregulation and its impact on anti-tumor immunity.
• To correlate PD-L1 expression with clinical features and potential response to immunotherapy.

Main Methods:

• In vitro studies using solid tumor cells to assess PD-L1 regulation by IFN-γ via the JAK-STAT pathway.
• Evaluation of the effect of IFN-γ on cytotoxic T-lymphocyte (CTL) activity and response to anti-PD-L1 mAb.
• Analysis of clinical gastric cancer samples to correlate tumor membrane PD-L1 expression with CD8+ T cells and IFN-γ levels.

Main Results:

• In vitro, IFN-γ upregulated PD-L1 on tumor cells through the JAK-STAT pathway, reducing CTL cytotoxicity.
• Pre-treatment with anti-PD-L1 mAb enhanced anti-tumor CTL activity following IFN-γ exposure.
• PD-L1 expression correlated with epithelial-mesenchymal transition phenotype in tumor cells.
• In gastric cancer samples, PD-L1 expression positively correlated with stromal CD8+ T cells and tumor IFN-γ.

Conclusions:

• IFN-γ-induced PD-L1 upregulation is a key mechanism affecting anti-tumor immunity in gastric cancer.
• Gastric cancer patients with high CD8+ T-cell infiltration may exhibit increased sensitivity to anti-PD-1/PD-L1 mAb therapy.
• These findings highlight the importance of the tumor microenvironment in guiding immunotherapy strategies for gastric cancer.