Background and Aims: HCC, the third leading cause of cancer-related death, arises in the context of liver fibrosis. Although HCC is generally poorly fibrogenic, some tumors harbor focal intratumor extracellular matrix (ECM) deposits called “fibrous nests.” To date, the molecular composition and clinical relevance of these ECM deposits have not been fully defined. Approach and Results: We performed quantitative matrisome analysis by tandem mass tags mass spectrometry in 20 human cancer specific matrisome (HCCs) with high or low-grade intratumor fibrosis and matched nontumor tissues, as well as in 12 livers from mice treated with vehicle, carbon tetrachloride, or diethylnitrosamine. We found 94 ECM proteins differentially abundant between high and low-grade fibrous nests, including interstitial and basement membrane components, such as several collagens, glycoproteins, proteoglycans, enzymes involved in ECM stabilization and degradation, and growth factors. Pathway analysis revealed a metabolic switch in high-grade fibrosis, with enhanced glycolysis and decreased oxidative phosphorylation. Integrating the quantitative proteomics with transcriptomics from HCCs and nontumor livers (n = 2,285 samples), we identified a subgroup of fibrous nest HCCs, characterized by cancer-specific ECM remodeling, expression of the WNT/TGFB (S1) subclass signature, and poor patient outcome. Fibrous nest HCCs abundantly expressed an 11-fibrous-nest–protein signature, associated with poor patient outcome, by multivariate Cox analysis, and validated by multiplex immunohistochemistry. Conclusions: Matrisome analysis highlighted cancer-specific ECM deposits, typical of the WNT/TGFB HCC subclass, associated with poor patient outcomes. Hence, histologic reporting of intratumor fibrosis in HCC is of clinical relevance.

Background & Aims: Excessive deposition and crosslinking of extracellular matrix increases liver density and stiffness, promotes fibrogenesis, and increases resistance to fibrinolysis. An emerging therapeutic opportunity in liver fibrosis is to target the composition of the extracellular matrix or block pathogenic communication with surrounding cells. However, the type and extent of extracellular changes triggering liver fibrosis depend on the underlying etiology. Our aim was to unveil matrisome genes not dependent on etiology, which are clinically relevant to liver fibrosis. Approach & Results: We used transcriptomic profiles from liver fibrosis cases of different etiologies to identify and validate liver fibrosis-specific matrisome genes (LFMGs) and their clinical and biological relevance. Dysregulation patterns and cellular landscapes of LFMGs were further explored in mouse models of liver fibrosis progression and regression by bulk and single-cell RNA sequencing. We identified 35 LFMGs, independent of etiology, representing an LFMG signature defining liver fibrosis. Expression of the LFMG signature depended on histological severity and was reduced in regressive livers. Patients with liver fibrosis, even with identical pathological scores, could be subclassified into LFMG^Low and LFMG^High, with distinguishable clinical, cellular, and molecular features. Single-cell RNA sequencing revealed that microfibrillar-associated protein 4⁺ activated HSC increased in LFMG^High patients and were primarily responsible for the LFMG signature expression and dysregulation. Conclusions: The microfibrillar-associated protein 4⁺ -activated HSC-derived LFMG signature classifies patients with liver fibrosis with distinct clinical and biological characteristics. Our findings unveil hidden information from liver biopsies undetectable using traditional histologic assessments.

Chronic hepatitis B virus (HBV) infection changes the composition of the extracellular matrix (ECM) and enables the onset and progression of hepatocellular carcinoma (HCC). The ensemble of ECM proteins and associated factors is a major component of the tumor microenvironment. Our aim was to unveil the matrisome genes from HBV‐related HCC. Transcriptomic and clinical profiles from 444 patients with HBV‐related HCC were retrieved from the Gene Expression Omnibus (GEO) and Cancer Genome Atlas (TCGA) repositories. Matrisome genes associated with HBV‐related hepatocarcinogenesis, matrisome gene modules, HCC subgroups, and liver‐specific matrisome genes were systematically analyzed, followed by identification of their biological function and clinical relevance. Eighty matrisome genes, functionally enriched in immune response, ECM remodeling, or cancer‐related pathways, were identified as associated with HBV‐related HCC, which could robustly discriminate HBV‐related HCC tumor from nontumor samples. Subsequently, four significant matrisome gene modules were identified as showing functional homogeneity linked to cell cycle activity. Two subgroups of patients with HBV‐related HCC were classified based on the highly correlated matrisome genes. The high‐expression subgroup (15.0% in the TCGA cohort and 17.9% in the GEO cohort) exhibited favorable clinical prognosis, activated metabolic activity, exhausted cell cycle, strong immune infiltration, and lower tumor purity. Four liver‐specific matrisome genes (F9, HPX [hemopexin], IGFALS [insulin‐like growth‐factor‐binding protein, acid labile subunit], and PLG [plasminogen]) were identified as involved in HBV‐related HCC progression and prognosis. Conclusion: This study identified the expression and function of matrisome genes from HBV‐related hepatocarcinogenesis, providing major insight to understand HBV‐related HCC and develop potential therapeutic opportunities.

Osteopontin (OPN) expression correlates with tumor progression in many cancers, including hepatocellular carcinoma (HCC); however, its role in the onset of HCC remains unclear. We hypothesized that increased hepatocyte‐derived OPN is a driver of hepatocarcinogenesis. Analysis of a tissue microarray of 366 human samples revealed a continuous increase in OPN expression during hepatocarcinogenesis. In patients with cirrhosis, a transcriptome‐based OPN correlation network was associated with HCC incidence along 10 years of follow‐up, together with messenger RNA (mRNA) signatures of carcinogenesis. After diethylnitrosamine (DEN) injection, mice with conditional overexpression of Opn in hepatocytes (Opn ^Hep transgenic [Tg]) showed increased tumor burden. Surprisingly, mice with conditional ablation of Opn in hepatocytes (Opn ^ΔHep) expressed a similar phenotype. The acute response to DEN was reduced in Opn ^ΔHep, which also showed more cancer stem/progenitor cells (CSCs, CD44⁺AFP⁺) at 5 months. CSCs from Opn ^Hep Tg mice expressed several mRNA signatures known to promote carcinogenesis, and mRNA signatures from Opn ^Hep Tg mice were associated with poor outcome in human HCC patients. Treatment with rOPN had little effect on CSCs, and their progression to HCC was similar in Opn ^−/− compared with wild‐type mice. Finally, ablation of Cd44, an OPN receptor, did not reduce tumor burden in Cd44 ^−/− Opn ^Hep Tg mice. Conclusions: Hepatocyte‐derived OPN acts as a tumor suppressor at physiological levels by controlling the acute response to DEN and the presence of CSCs, while induction of OPN is pro‐tumorigenic. This is primarily due to intracellular events rather that by the secretion of the protein and receptor activation.

Background and Aims: Early allograft dysfunction (EAD) is a severe event leading to graft failure after liver transplant (LT). Extracellular high-mobility group box-1 (HMGB1) is a damage-associated molecular pattern that contributes to hepatic ischemia-reperfusion injury (IRI). However, the contribution of intracellular HMGB1 to LT graft injury remains elusive. We hypothesized that intracellular neutrophil-derived HMGB1 from recipients protects from post-LT EAD. Approach and Results: We generated mice with conditional ablation or overexpression of Hmgb1 in hepatocytes, myeloid cells, or both. We performed LTs and injected lipopolysaccharide (LPS) to evaluate the effect of intracellular HMGB1 in EAD. Ablation of Hmgb1 in hepatocytes and myeloid cells of donors and recipients exacerbated early allograft injury after LT. Ablation of Hmgb1 from liver grafts did not affect graft injury; however, lack of Hmgb1 from recipient myeloid cells increased reactive oxygen species (ROS) and inflammation in liver grafts and exacerbated injury. Neutrophils lacking HMGB1 were more activated, showed enhanced pro-oxidant and pro-inflammatory signatures, and reduced biosynthesis and metabolism of inositol polyphosphates (InsPs). On LT reperfusion or LPS treatment, there was significant neutrophil mobilization and infiltration into the liver and enhanced production of ROS and pro-inflammatory cytokines when intracellular Hmgb1 was absent. Depletion of neutrophils using anti-Ly6G antibody attenuated graft injury in recipients with myeloid cell Hmgb1 ablation. Conclusions: Neutrophil HMGB1 derived from recipients is central to regulate their activation, limits the production of ROS and pro-inflammatory cytokines, and protects from early liver allograft injury.