A Stromal-Centered Single-Cell Landscape Identifies POSTN⁺ Fibroblasts as a High-Risk Stromal Subset in...

Hepatocellular carcinoma (HCC) develops within a complex microenvironment in which cancer-associated fibroblasts (CAFs) are abundant, yet their heterogeneity and functional roles remain incompletely understood. Here, we integrated multi-site single-cell RNA sequencing of Normal liver, primary Tumor, portal vein tumor thrombus (PVTT), and metastatic Lymph node samples with bulk transcriptomic analysis, cell-cell communication inference, and functional assays to define stromal programs associated with HCC progression. We identified four transcriptionally distinct CAF subsets: SGCA⁺ mCAFs, POSTN⁺ mCAFs, TDO2⁺ CAFs, and CXCL14⁺ iCAFs, each showing site-specific distribution and distinct prognostic relevance. Among them, POSTN⁺ mCAFs were enriched for extracellular matrix organization and integrin signaling, and their signatures were consistently associated with poor overall survival across independent cohorts. Ligand-receptor analysis identified POSTN⁺ mCAFs as highly connected stromal hubs communicating with malignant and myeloid cells through ECM-integrin, collagen-SDC4, and chemokine pathways. Consistently, tumor-derived POSTN-high fibroblasts promoted hepatoma cell proliferation, migration, and invasion in vitro. Together, these findings identify POSTN⁺ mCAFs as a transcriptionally distinct and functionally pro-tumorigenic stromal subset in HCC, supporting POSTN-centered stromal programs as candidate markers of aggressive tumor microenvironments and a basis for future mechanistic investigation.