Hypoxia-induced ADAM8⁺ macrophages and FAP⁺ fibroblasts form an extracellular matrix–remodeling niche at the tumor boundary in HCC

Abstract In hepatocellular carcinoma (HCC), stromal and immune components shape invasion and metastasis. To identify the cellular states that drive extracellular matrix (ECM) remodeling, define their organization at the tumor margin, and evaluate their association with prognosis, we profiled stromal regions at the tumor margin using single-cell RNA sequencing (scRNA-seq), spatial transcriptomics, and multiplex immunofluorescence. Across scRNA-seq profiles from 79 patients, we identified a hypoxia-associated population of tumor-associated macrophages with high ADAM8 expression and upregulated ECM remodeling programs. Spatial transcriptomics and histology placed these ADAM8⁺ macrophages in stromal regions with disorganized collagen. They were often in hypoxic zones around necrosis and adjacent to FAP⁺ fibroblasts. Ligand–receptor analysis predicted engagement of the collagen–CD44 axis between the two cell types. In vitro, hypoxia induced expression of ADAM8 in macrophages. ADAM8 knockdown reduced the induction of TNF-α, IL-6, and IL-1β and weakened the ability of macrophages to activate fibroblasts. In tissue microarrays, a higher fraction of ADAM8⁺ macrophages among CD68⁺ cells predicted shorter overall and recurrence-free survival. Consistently, in a murine HCC model, pharmacological inhibition of ADAM8 decreased FAP⁺ fibroblast abundance. Overall, the data show that ADAM8⁺ macrophages and FAP⁺ fibroblasts form a hypoxia-linked ECM remodeling niche at the tumor boundary. This stromal remodeling unit associates with poor prognosis and suggests testable targets for stroma-focused therapy for HCC.