Liver specific deletion of CYLDexon7/8 induces severe biliary damage, fibrosis and increases hepatocarcinogenesis in mice.
OBJECTIVE
CYLD is a tumor suppressor gene that is mutated in familial cylindromatosis, an autosomal dominant predisposition to tumors of skin appendages. Reduced CYLD expression has been observed in other tumor entities, including hepatocellular carcinoma. In the present study, we analyzed the role of CYLD in liver homeostasis and hepatocarcinogenesis in vivo.


METHODS
Mice with liver-specific deletion of CYLDexon7/8 (CYLD(FF)xAlbCre) were generated. Liver tissues were histologically analyzed and oval cell activation was investigated. Hepatocarcinogenesis was induced by diethylnitrosamine/phenobarbital (DEN/PB). Microarray expression profiling of livers was performed in untreated as well as DEN/PB-treated mice. NF-κB signaling was assessed by ELISA, quantitative real-time PCR, and Western blotting.


RESULTS
CYLD(FF)xAlbCre hepatocytes and cholangiocytes did not express full-length CYLD (FL-CYLD) protein but showed increased expression of the naturally occurring short-CYLD splice variant (s-CYLD). CYLD(FF)xAlbCre mice exhibited a prominent biliary phenotype with ductular reaction and biliary-type fibrosis. In addition, CYLD(FF)xAlbCre mice showed a significantly increased sensitivity towards DEN/PB-induced hepatocarcinogenesis. Moreover, we could observe the development of cholangiocellular carcinoma, in line with enhanced oval cell activity. NF-κB-signaling was increased in livers of CYLD(FF)xAlbCre mice and likely contributed to the inflammatory and fibrotic response.


CONCLUSIONS
The deletion of exon7/8 of the CYLD gene activates oval cells, leads to a biliary phenotype, and increases the susceptibility towards carcinogenesis in the liver. Thus, our study presents a novel model of biliary damage and liver fibrosis, followed by cancer development.
National Center for Tumor Diseases, Department of Medical Oncology, University Clinic of Heidelberg, Heidelberg, Germany.
Toni
T
Urbanik
Regina Johanna
RJ
Boger
Thomas
T
Longerich
Katharina
K
Becker
Karl Roland
KR
Ehrenberg
Nadine
N
Hövelmeyer
Matthias
M
Hahn
Marcus
M
Schuchmann
Dirk
D
Jäger
Ari
A
Waisman
Marcus Alexander
MA
Wörns
Henning
H
Schulze-Bergkamen
D000818:Animals; D001660:Biliary Tract Diseases / Q000235:genetics* / Q000473:pathology; D003546:Cysteine Endopeptidases / Q000235:genetics* / Q000378:metabolism*; D000074749:Deubiquitinating Enzyme CYLD; D004128:Dimethylnitrosamine / Q000009:adverse effects; D004195:Disease Models, Animal; D005091:Exons / Q000235:genetics*; D005355:Fibrosis; D017353:Gene Deletion; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006706:Homeostasis; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D008113:Liver Neoplasms / Q000139:chemically induced / Q000453:epidemiology* / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D010634:Phenobarbital / Q000009:adverse effects; D010641:Phenotype; D012307:Risk Factors
C511601:CYLD protein, mouse; D000074749:Deubiquitinating Enzyme CYLD; D003546:Cysteine Endopeptidases; D004128:Dimethylnitrosamine; D010634:Phenobarbital