Hepatocyte specific expression of an oncogenic variant of β-catenin results in cholestatic liver disease

BACKGROUND: The Wnt/β-catenin signaling pathway plays a crucial role in embryonic development, tissue homeostasis, wound healing and malignant transformation in different organs including the liver. The consequences of continuous β-catenin signaling in hepatocytes remain elusive. RESULTS: Livers of Ctnnb1(CA hep) mice were characterized by disturbed liver architecture, proliferating cholangiocytes and biliary type of fibrosis. Serum ALT and bile acid levels were significantly increased in Ctnnb1(CA hep) mice. The primary bile acid synthesis enzyme Cyp7a1 was increased whereas Cyp27 and Cyp8b1 were reduced in Ctnnb1(CA hep) mice. Expression of compensatory bile acid transporters including Abcb1, Abcb4, Abcc2 and Abcc4 were significantly increased in Ctnnb1(CA hep) mice while Ntcp was reduced. Accompanying changes of bile acid transporters favoring excretion of bile acids were observed in intestine and kidneys of Ctnnb1(CA hep) mice. Additionally, disturbed bile acid regulation through the FXR-FGF15-FGFR4 pathway was observed in mice with activated β-catenin. MATERIALS AND METHODS: Mice with a loxP-flanked exon 3 of the Ctnnb1 gene were crossed to Albumin-Cre mice to obtain mice with hepatocyte-specific expression of a dominant stable form of β-catenin (Ctnnb1(CA hep) mice). Ctnnb1(CA hep) mice were analyzed by histology, serum biochemistry and mRNA profiling. CONCLUSIONS: Expression of a dominant stable form of β-catenin in hepatocytes results in severe cholestasis and biliary type fibrosis.