Mechanical induction of the tumorigenic β-catenin pathway by tumour growth pressure.

The tumour microenvironment may contribute to tumorigenesis owing to mechanical forces such as fibrotic stiffness or mechanical pressure caused by the expansion of hyper-proliferative cells. Here we explore the contribution of the mechanical pressure exerted by tumour growth onto non-tumorous adjacent epithelium. In the early stage of mouse colon tumour development in the Notch(+)Apc(+/1638N) mouse model, we observed mechanistic pressure stress in the non-tumorous epithelial cells caused by hyper-proliferative adjacent crypts overexpressing active Notch, which is associated with increased Ret and β-catenin signalling.

Portal myofibroblasts promote vascular remodeling underlying cirrhosis formation through the release of microparticles.

Unlabelled: Liver fibrosis expanding from portal tracts and vascular remodeling are determinant factors in the progression of liver diseases to cirrhosis. In the present study, we examined the potential contribution of portal myofibroblasts (PMFs) to the vascular changes leading to cirrhosis. The analyses of liver cells based on the transcriptome of rat PMFs, compared to hepatic stellate cell HSC-derived myofibroblasts in culture, identified collagen, type XV, alpha 1 (COL15A1) as a marker of PMFs.

Vitamin D nuclear receptor deficiency promotes cholestatic liver injury by disruption of biliary epithelial cell junctions in mice.

Unlabelled: Alterations in apical junctional complexes (AJCs) have been reported in genetic or acquired biliary diseases. The vitamin D nuclear receptor (VDR), predominantly expressed in biliary epithelial cells in the liver, has been shown to regulate AJCs. The aim of our study was thus to investigate the role of VDR in the maintenance of bile duct integrity in mice challenged with biliary-type liver injury.

Mitogenic insulin receptor-A is overexpressed in human hepatocellular carcinoma due to EGFR-mediated dysregulation of RNA splicing factors.

Insulin receptor (IR) exists as two isoforms resulting from the alternative splicing of IR pre-mRNA. IR-B promotes the metabolic effects of insulin, whereas IR-A rather signals proliferative effects. IR-B is predominantly expressed in the adult liver.

Epidermal growth factor receptor and HER-3 restrict cell response to sorafenib in hepatocellular carcinoma cells.

Background & Aims: Sorafenib is the standard of care for the treatment of advanced hepatocellular carcinoma (HCC). However, primary and acquired resistance is observed in patients. We examined whether gefitinib, which inhibits both epidermal growth factor receptor (EGFR) and HER-3 phosphorylation, could improve HCC cell response to sorafenib.

Defects in gallbladder emptying and bile Acid homeostasis in mice with cystic fibrosis transmembrane conductance regulator deficiencies.

Background & Aims: Patients with cystic fibrosis (CF) have poorly defined defects in biliary function. We evaluated the effects of cystic fibrosis transmembrane conductance regulator (CFTR) deficiency on the enterohepatic disposition of bile acids (BAs).

Methods: Bile secretion and BA homeostasis were investigated in Cftr(tm1Unc) (Cftr-/-) and CftrΔF508 (ΔF508) mice.

Distinct proteomic features of two fibrogenic liver cell populations: hepatic stellate cells and portal myofibroblasts.

In chronic liver diseases, the accumulation of extracellular matrix leading to fibrosis is caused by myofibroblasts, the origins of which are debatable. We performed a comparative proteomic study to identify markers and gain insight into distinct functions of myofibroblasts derived either from hepatic stellate cells (HSCs) or from portal mesenchymal cells. After isolation from normal liver and culture in similar conditions, myofibroblastic HSCs (MF-HSCs) presented enlarged cytoplasms whereas portal myofibroblasts (PMFs) were more proliferative, and formed more stress fibers.

IGF-1R contributes to stress-induced hepatocellular damage in experimental cholestasis.

The insulin-like growth factor type 1 receptor (IGF-1R) controls aging and cellular stress, both of which play major roles in liver disease. Stimulation of insulin-like growth factor signaling can generate cell death in vitro. Here, we tested whether IGF-1R contributes to stress insult in the liver.

Ezrin-radixin-moesin-binding phosphoprotein (EBP50), an estrogen-inducible scaffold protein, contributes to biliary epithelial cell proliferation.

Ezrin-radixin-moesin-binding phosphoprotein 50 (EBP50) anchors and regulates apical membrane proteins in epithelia. EBP50 is inducible by estrogen and may affect cell proliferation, although this latter function remains unclear. The goal of this study was to determine whether EBP50 was implicated in the ductular reaction that occurs in liver disease.

Impact of nutrition on phenotype in CFTR-deficient mice.

To elucidate the impact of nutrition in cystic fibrosis (CF), we compared the phenotypic traits of Cftr -/- mice fed either a lipid-enriched liquid diet (Peptamen) or a standard chow combined with polyethylenglycol osmotic laxative (PEG), two strategies commonly used to prevent intestinal obstruction in CF mice. Survival, growth, liver, and ventilatory status were determined in Cftr -/- and Cftr +/+ mice, followed-up until 120 d. Ventilation was recorded in conscious animals using whole-body plethysmography.

Hypoxia-induced changes in the expression of rat hepatobiliary transporter genes.

Cholestatic disorders may arise from liver ischemia (e.g., in liver transplantation) through various mechanisms.

Prominent contribution of portal mesenchymal cells to liver fibrosis in ischemic and obstructive cholestatic injuries.

Liver fibrosis is produced by myofibroblasts of different origins. In culture models, rat myofibroblasts derived from hepatic stellate cells (HSCs) and from periductal portal mesenchymal cells, show distinct proliferative and immunophenotypic evolutive profiles, in particular regarding desmin microfilament (overexpressed vs shut-down, respectively). Here, we examined the contributions of both cell types, in two rat models of cholestatic injury, arterial liver ischemia and bile duct ligation (BDL).

Hepatocyte proliferation during liver regeneration is impaired in mice with liver-specific IGF-1R knockout.

Recent evidence indicates that growth hormone (GH) is involved in liver regeneration. To test whether insulin-like growth factor I (IGF-I) mediates this effect, we studied liver regeneration induced by partial hepatectomy in liver-specific IGF type 1 receptor knockout (LIGFREKO) mice. The absence of IGF-1R caused a significant decrease in hepatocyte proliferation in males (-52%), but not in females, as assessed by Ki67 immunohistochemistry.

Overexpression of insulin receptor substrate-2 in human and murine hepatocellular carcinoma.

De-regulations in insulin and insulin-like growth factor (IGF) pathways may contribute to hepatocellular carcinoma. Although intracellular insulin receptor substrate-2 (IRS-2) is the main effector of insulin signaling in the liver, its role in hepatocarcinogenesis is unknown. Here, we show that IRS-2 was overexpressed in two murine models of hepatocarcinogenesis: administration of diethylnitrosamine and hepatic overexpression of SV40 large T antigen.

Adaptative bile duct proliferative response in experimental bile duct ischemia.

Background/aims: A rat model of bile duct ischemia was established and used to examine the potential of bile duct proliferation to provide an adaptative response in cholestatic disorders.

Methods: Rats underwent partial or complete arterial deprivation of the liver. Serum biochemical tests, histological analyses and bile secretion measurements were performed at different time points up to 6 weeks after surgery.

Gefitinib, an EGFR inhibitor, prevents hepatocellular carcinoma development in the rat liver with cirrhosis.

Epidermal growth factor receptor (EGFR) binds transforming growth factor alpha (TGF-alpha) which is mitogenic for hepatocytes. Diverse lines of evidence suggest that activation of the TGF-alpha /EGFR pathway contributes to hepatocellular carcinoma (HCC) formation. Herein, we developed an experimental model of cirrhosis giving rise to HCC and tested the antitumoral effect of gefitinib, a selective EGFR tyrosine kinase inhibitor, in this model.

The myofibroblastic conversion of peribiliary fibrogenic cells distinct from hepatic stellate cells is stimulated by platelet-derived growth factor during liver fibrogenesis.

The origin of myofibroblasts and the factors promoting their differentiation during liver fibrogenesis remain uncertain. During biliary-type fibrogenesis, the proliferation and chemoattraction of hepatic stellate cells (HSC) toward bile ducts is mediated by platelet-derived growth factor (PDGF), while myofibroblastic conversion of peribiliary cells distinct from HSC also occurs. We herein examined the phenotype of these peribiliary myofibroblasts as compared with myofibroblastic HSC and tested whether their differentiation was affected by PDGF.

Contribution of mrp2 in alterations of canalicular bile formation by the endothelin antagonist bosentan.

Background/aims: Bosentan, a dual endothelin ET(A/B) receptor antagonist, may cause dose-dependent reversible cholestatic liver injury. We herein tested whether bosentan or metabolites, both eliminated in bile, induce alterations in bile secretion.

Methods: Bile flow and output of bile constituents were monitored in pentobarbital-anesthetized rats with biliary fistulas.

Hypoxia-induced VEGF and collagen I expressions are associated with angiogenesis and fibrogenesis in experimental cirrhosis.

Cirrhosis consists of hepatocyte nodules surrounded by a highly vascularized fibrous tissue. We previously showed that the development of biliary cirrhosis in the rat is associated with the occurrence of hepatocellular hypoxia and the induction of hepatic angiogenesis. We herein examined the occurrence of hypoxia in an experimental model of diethylnitrosamine (DEN)-induced cirrhosis.