Molecular and cellular consequences of tumor-autonomous IL-6 signaling in intrahepatic cholangiocarcinoma

Design: We generated CRISPR-activated IL-6high patient-derived iCCA cell models and characterized them using RNA-sequencing and secretome analysis. Therapeutic vulnerabilities were determined with high-throughput drug screening, while the impact of tumor-conditioned media on the phenotype and function of circulating immune cells was assessed with high-dimensional flow cytometry. Spatial transcriptomic analysis (Visium HD) was performed on 14 resected tumors to quantify tumor-derived IL6 expression, cell type composition, and ligand-receptor interactions in the tumor microenvironment.

Results: Chronic IL-6 signaling drives distinct transcriptional programs, metabolic vulnerabilities, and immunomodulatory effects. IL-6high tumor cells confer sensitivity to nicotinamide phosphoribosyltransferase (NAMPT) inhibition, leading to disrupted mitochondrial fitness and selective IL-6 downregulation. Chronic IL-6 signaling also alters the tumor secretome, which modulates immune cell composition and impairs cellular function, including the suppression of MER proto-oncogene tyrosine kinase (MerTK)-mediated macrophage efferocytosis.

Spatial transcriptomic analysis confirms that tumor IL6 expression correlates with myeloid cell depletion, cancer-associated fibroblast (CAF) enrichment, and enhanced tumor-CAF communication. Conclusions: These findings uncover a multifaceted role for IL-6 in shaping tumor-intrinsic, microenvironmental, and macroenvironmental features, revealing novel molecular mechanisms and potential therapeutic vulnerabilities in iCCA.