Disruption of thrombospondin 1/2-integrin β1 axis impairs cell adhesion and tumor growth in intrahepatic cholangiocarcinoma

Abstract Elevated expression of THBS1 and THBS2 in intrahepatic cholangiocarcinoma (iCCA) contributes to tumor growth and metastatic dissemination. Both proteins are predominantly produced by cancer-associated fibroblasts (CAFs) and iCCA cells, enhancing the interaction of malignant cholangiocytes with the extracellular matrix (ECM). Here, we identify integrin α3β1 and α6β1 as the cognate receptors for THBS1 and THBS2 on iCCA cell surface. Disruption of the THBS1-integrin β1 axis via monoclonal antibodies, THBS1-derived peptides, or THBS1 knockout (KO) iCCA cells reduces autocrine and paracrine integrin β1 activation, resulting in decreased ECM adhesion in both two-dimensional and three-dimensional assays. Loss of endogenous THBS1 also alters cell morphology, weakens intracellular junctions, and prevents tumor formation in mouse xenograft models. These findings identify the THBS1/THBS2-integrin β1 axis as a key driver of iCCA cell adhesion and malignancy, supporting its potential as a therapeutic target for iCCA-specific interventions.