ASK1/ p38 axis inhibition blocks the release of mitochondrial "danger signals" from hepatocytes and suppresses progression to cirrhosis and liver cancer.

BACKGROUND AND AIMS: Apoptosis Signal-regulating Kinase 1 (ASK1) is activated by various pathological stimuli and induces cell apoptosis through downstream p38 activation. We studied the effect of pharmacological ASK1 inhibition on cirrhosis and its sequelae using comprehensive preclinical in vivo and in vitro systems. APPROACH AND RESULTS: Short-term (4-6 wk) and long-term (24-44 wk) ASK1 inhibition using small molecule GS-444217 was tested in thioacetamide-induced and BALB/c. Mdr2-/- murine models of cirrhosis and HCC, and in vitro using primary hepatocyte cell death assays. Short-term GS-444217 therapy in both models strongly reduced phosphorylated p38, hepatocyte death, and fibrosis by up to 50%. Profibrogenic release of mitochondrial DAMP mitochondrial deoxyribonucleic acid from dying hepatocytes was blocked by ASK1 or p38 inhibition. Long-term (24 wk) therapy in BALBc.Mdr2 - / - model resulted in a moderate 25% reduction in bridging fibrosis, but not in net collagen deposition. Despite this, the development of cirrhosis was effectively prevented, with strongly reduced p21 + hepatocyte staining (by 72%), serum ammonia levels (by 46%), and portal pressure (average 6.07 vs. 8.53 mm Hg in controls). Extended ASK1 inhibition for 44 wk in aged BALB/c. Mdr2-/- mice resulted in markedly reduced tumor number and size by ~50% compared to the control group. CONCLUSIONS: ASK1 inhibition suppresses the profibrogenic release of mitochondrial deoxyribonucleic acid from dying hepatocytes in a p38-dependent manner and protects from liver fibrosis. Long-term ASK1 targeting resulted in diminished net antifibrotic effect, but the progression to liver cirrhosis and cancer in BALBc/ Mdr2- / - mice was effectively inhibited. These data support the clinical evaluation of ASK1 inhibitors in fibrotic liver diseases.

Transposon-based oncogene integration in Abcb4(Mdr2)-/- mice recapitulates high susceptibility to cholangiocarcinoma in primary sclerosing cholangitis.

BACKGROUND AND AIMS: Cholangiocarcinoma (CCA) is a dreaded complication of primary sclerosing cholangitis (PSC), difficult to diagnose and associated with high mortality. Lack of animal models of CCA recapitulating the hepatic microenvironment of sclerosing cholangitis hinders development of novel treatments. Here we sought to develop such PSC-associated CCA model in mice. METHODS: Ten-week-old Mdr2-/- mice with congenital PSC-like disease, and healthy wild-type littermates were subjected to either modified retrograde biliary instillation or hydrodynamic tail vein injection of sleeping beauty transposon-transposase plasmid system with activated AKT (myr-AKT) and Yap (YapS127A) protooncogenes (SB AKT/YAP1). The role of TGFß was interrogated via ALK5 inhibitor (SB-525334) administration. Tumor phenotype, burden and desmoplastic reaction were analyzed histologically and via RNA-seq. RESULTS: While SB AKT/YAP1 plasmids via retrograde biliary injection caused tumors in Mdr2-/-, only 26.67% (4/15) of these tumors were CCA. Alternatively, hydrodynamic tail vein injection of SB AKT/YAP1 resulted in robust tumorigenesis in all fibrotic Mdr2-/- mice with high CCA burden compared to healthy mice. Tumors phenotypically resembled human CCA, expressed multiple CCA (but not hepatocellular carcinoma) markers, and exhibited a profound desmoplastic reaction. RNA-seq analysis revealed profound transcriptional changes in CCA evolving in PSC-like context, with specific alterations in multiple immune pathways. Pharmacological TGFß inhibition led to enhanced immune cell tumor infiltration, reduced tumor burden and suppressed desmoplastic collagen accumulation compared to placebo CONCLUSION: We established a new high-fidelity cholangiocarcinoma model in mice, termed SB CCA.Mdr2-/-, which recapitulates the increased susceptibility to CCA in the setting of biliary injury and fibrosis observed in PSC. Through transcriptomics and pharmacological studies, we show dysregulation of multiple immune pathways and TGFß signaling as potential drivers of CCA in PSC-like microenvironment. IMPACT AND IMPLICATIONS: There is a lack of animal models for primary sclerosing cholangitis (PSC) related cholangiocarcinoma (PSC-CCA). We have developed and characterized a new mouse model of PSC-CCA, termed SB CCA.Mdr2-/-, which features reliable tumor induction in PSC-like background of biliary injury and fibrosis. Global gene expression alterations were identified and standardized tools, including automated whole slide image analysis methodology for tumor burden and feature analysis, were established to enable systematic research into PSC-CCA biology and formal pre-clinical drug testing.