Hypoxia drives ANGPTL4 expression in tumor-associated macrophages and promotes intrahepatic cholangiocarcinoma intrahepatic metastasis.

Intrahepatic metastasis (IM) is a critical predictor of poor prognosis in intrahepatic cholangiocarcinoma (iCCA), yet the tumor microenvironmental mechanisms driving this process remain poorly understood. By integrating single-cell RNA sequencing data from 15 iCCA samples with a public transcriptomic cohort of 255 patients (OEP001105), we characterized the immune and malignant epithelial landscapes associated with IM. We identified ANGPTL4-positive tumor-associated macrophages and hypoxia-associated malignant epithelial cells that were enriched in the IM group. Mechanistically, hypoxia induced the transcription factor CEBPB in macrophages, which directly activated ANGPTL4 transcription. Macrophage-derived ANGPTL4 subsequently engaged Integrin α5β1 on iCCA cells, activating the FAK/Src/GSK3β/β-catenin signaling cascade, promoting β-catenin nuclear translocation, and inducing epithelial-mesenchymal transition-associated remodeling. Functional assays and in vivo metastasis models demonstrated that ANGPTL4 enhanced iCCA cell migration, invasion, and liver metastasis, whereas ANGPTL4 blockade attenuated these effects. Clinical validation using ELISA and multiplex immunofluorescence further showed that elevated serum and tissue ANGPTL4 levels were associated with tumor burden and IM. Collectively, our study reveals a hypoxia-driven tumor microenvironmental communication axis between tumor-associated macrophages and malignant epithelial cells, highlighting ANGPTL4 as a potential non-invasive serum biomarker and therapeutic target for iCCA intrahepatic metastasis.