Secreted AZGP1 induced by 5-FU binds to PD-L1 and promotes apoptosis in cholangiocarcinoma.

BACKGROUND: Cholangiocarcinoma (CCA) is an aggressive malignancy with limited treatment options and poor clinical outcomes. The identification of predictive biomarkers that can enhance chemotherapy efficacy and inform immune modulation remains an urgent unmet need. METHODS: We investigated the biological role and regulatory mechanisms of soluble AZGP1 in CCA using western blotting, ELISA, flow cytometry, and in vitro/in vivo functional assays. A combination of pharmacological treatments and gene expression analyses was employed to explore pathway dynamics and immune responses. RESULTS: We found that soluble AZGP1, which is typically downregulated in CCA, is significantly upregulated following 5-fluorouracil (5-FU) treatment. Mechanistically, 5-FU modulates the AKT–Foxo1 signaling pathway, promoting nuclear translocation of Foxo1 and activation of AZGP1. Elevated soluble AZGP1 levels were shown to interact with PD-L1, enhancing apoptosis in cancer cells. Analyses of peripheral blood mononuclear cells (PBMCs) further confirmed the immune-modulating potential of AZGP1 in the tumor microenvironment. CONCLUSIONS: Our findings reveal that soluble AZGP1 acts as a predictive biomarker for 5-FU efficacy in cholangiocarcinoma and exerts pro-apoptotic and immunomodulatory functions via interaction with PD-L1. These insights may contribute to the development of more precise and effective therapeutic strategies in CCA treatment. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s10020-025-01362-8.