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Liver-specific DICER1 syndrome model mice develop cystic liver tumors with defective primary cilia

ABSTRACT: DICER1 syndrome is a tumor predisposition syndrome caused by familial genetic mutations in DICER1. Pathogenic variants of DICER1 have been discovered in many rare cancers, including cystic liver tumors. However, the molecular mechanisms underlying liver lesions induced by these variants remain unclear. In the present study, we sought to gain a better understanding of the pathogenesis of these variants by generating a mouse model of liver-specific DICER1 syndrome. The mouse model developed bile duct hyperplasia with fibrosis, similar to congenital hepatic fibrosis, as well as cystic liver tumors resembling those in Caroli's syndrome, intrahepatic cholangiocarcinoma, and hepatocellular carcinoma. Interestingly, the mouse model of DICER1 syndrome showed abnormal formation of primary cilia in the bile duct epithelium, which is a known cause of bile duct hyperplasia and cyst formation. These results indicated that DICER1 mutations contribute to cystic liver tumors by inducing defective primary cilia. The mouse model generated in this study will be useful for elucidating the potential mechanisms of tumorigenesis induced by DICER1 variants and for obtaining a comprehensive understanding of DICER1 syndrome.

ORGANISM(S): Mus musculus

PROVIDER: GSE231487 | GEO | 2024/05/02

REPOSITORIES: GEO

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Project description:Liver dysfunction and cirrhosis affect vasculature in several organ systems and cause impairment of organ functions, thereby increasing morbidity and mortality. If a mouse model of hepatopulmonary syndrome (HPS) could be established, greater insight into the genetic basis of the disease would be gained. Our objectives were to establish a mouse model of lung injury after common bile duct ligation (CBDL) and to investigate pulmonary pathogenesis for application in future therapeutic approaches. Balb/c mice were subjected to CBDL. Immunohistochemical analyses and real-time quantitative reverse transcriptional polymerase chain reaction were performed on pulmonary tissues. The presence of HPS markers were detected by western blot and microarray analyses. We observed extensive proliferation of CD31-positive pulmonary vascular endothelial cells 2 weeks after CBDL, and identified 11 up-regulated and 8 down-regulated proteins that were associated with angiogenesis. MMP-9 protein was highly expressed at 3 weeks after CBDL, and less expressed in lungs of the control group. Contrary to our expectation, lung pathology in our mouse model exhibited differences from that of rat models, and the mechanisms responsible for these differences are unknown. This phenomenon may be explained by contrasting processes related to TNF induction of angiogenic signaling pathways in the inflammatory phase; thus, we suggest that our mouse model can be applied to pulmonary pathological analyses in the inflammatory phase, i.e., to systemic inflammatory response syndrome, acute lung injury, and MOD syndrome. After induction of anesthesia, a median abdominal incision was made and the common bile duct was identified. The duct was dissected carefully under a microscope, and doubly ligated with 7-0 Prolene and transected. In the sham operation (control) group, the duct was dissected without common bile duct ligation. Mice were sacrificed at 2 and 3 weeks after surgery. CD31-positive cells were assembled from three mice in each group.

Project description:We investigated a drug-induced liver injury (DILI) model in rats induced by methapyrilene (MPy) administration. MPy, a former antihistamine and anticholinergic drug, was withdrawn in the 1970ties due to its ability to initiate hepatocarcinogenesis and is now used to induce hepatobiliary injury and biliary epithelial cell hyperplasia. Male Wistar rats (8–10 weeks old, weighing 170–200 g) were randomly assigned to three dosing groups (n=6 per group and time-point) and dosed with MPy at 0, 30 and 80 mg/kg/day by oral gavage. After 4, 8 or 15 days, or after 14 days followed by a recovery period of 10 days (day 24) rats were sacrificed. Increased levels of ALAT, ASAT, AP and ɣ-GT as well as bili-t and total bile acids indicated liver damage (AP and ɣGT indicating biliary effects). They were detectable on day 7 at the high dose of 80 mg/kg MPy and persisted until day 15 at end of treatment. Histopathologically, vacuolation and necrosis of the hepatocytes (predominantly in the periportal region) were seen starting on day 3 - especially in animals treated with 80 mg/kg MPy. These findings were accompanied by periportal mononuclear inflammatory cell filtration. Bile duct proliferation, bile duct hyperplasia and increased numbers of mitoses of hepatocytes were evident at all treatment time points. The frequency and severity of these findings increased with dose and duration of the treatment. Gene expression analysis in liver tissues revealed highly significant transcriptional changes in the high dose group, detectable on day 4 and intensifying over time. Besides genes associated with apoptosis (CASP4, CASP12), detoxification (CYB4B) and proliferation (p21, CCNG1) several were related to bile acid metabolism or transport. For example, bile acid exporters OATP1, NTCP, OATP4 and MOAT1/ OATPB as well as the putative bile acid metabolizing enzymes AMACR, BAAT and ACOX2 were found down regulated in response to MPy treatment. In contrast, mRNAs encoding putative bile acid importers MRP2 and ABCC4 / MRP4 were found up regulated. Most of the deregulated levels returned to control values during the recovery phase except OATP1, MOAT1/ OATPB, which remained slightly elevated. Interestingly, OATP4 followed an inverse trend of deregulation after 10 days of recovery, presumably due to overcompensation. Overall, the expression changes found associated with bile acid metabolism or transport could be linked to detected bile acid level alterations in liver and plasma.

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Liver-specific DICER1 syndrome model mice develop cystic liver tumors with defective primary cilia

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