Background & Aims:
Cholangiocarcinoma (CCA) is a cancer of the hepatic bile ducts that is rarely resectable and associated with poor prognosis. New therapeutic strategies are urgently required. Tumour necrosis factor-like weak inducer of apoptosis (TWEAK) is known to signal via its receptor fibroblast growth factor-inducible 14 (Fn14) and induce cholangiocyte and myofibroblast proliferation in liver injury. Its role in CCA remains undefined.
The expression of TWEAK ligand and Fn14 receptor was assessed immunohistochemically and by bulk RNA and single cell transcriptomics of human liver tissue. Spatiotemporal dynamics of pathway regulation were comprehensively analysed in rat and mouse thioacetamide (TAA)-mediated CCA. Flow cytometry, qPCR and proteomic analyses of CCA cell lines and conditioned medium experiments with primary macrophages were performed to evaluate TWEAK/Fn14 downstream functions. In vivo pathway manipulation was assessed via TWEAK overexpression in NICD/AKT-induced CCA or genetic Fn14 knockout during TAA-mediated carcinogenesis.
Our data reveal TWEAK and Fn14 overexpression in multiple human CCA cohorts, and Fn14 upregulation in early TAA-induced carcinogenesis. TWEAK regulated the secretion of factors from CC-SW-1 and SNU-1079 CCA cells, inducing polarisation of proinflammatory CD206+ macrophages. Pharmacological blocking of the TWEAK downstream target chemokine monocyte chemoattractant protein 1 (MCP-1) significantly reduced CCA xenograft growth, while TWEAK overexpression drove cancer-associated fibroblast proliferation and collagen deposition in the tumour niche. Genetic Fn14 ablation significantly reduced inflammatory, fibrogenic and ductular responses during carcinogenic TAA-mediated injury.
These novel data provide evidence for the action of TWEAK/Fn14 on macrophage recruitment and phenotype, and cancer-associated fibroblast proliferation in CCA. Targeting TWEAK/Fn14 and its downstream signals may provide a means to inhibit CCA niche development and tumour growth.