A high-cholesterol diet promotes steatohepatitis and liver tumorigenesis in HCV core gene transgenic mice
Previous epidemiological studies have suggested a link between high-cholesterol intake and liver disease progression, including hepatocellular carcinoma (HCC). However, the precise mechanism of hepatotoxicity and hepatocarcinogenesis caused by excessive cholesterol consumption remains unclear. We aimed to investigate the impact of dietary cholesterol using hepatitis C virus core gene transgenic (HCVcpTg) mice, which spontaneously developed HCC with age. Male HCVcpTg mice were treated for 15 months with either a control diet or an isocaloric diet containing 1.5% cholesterol, and liver phenotypes and tumor-associated signaling pathways were evaluated. The high-cholesterol diet-fed HCVcpTg mice exhibited a significantly higher incidence of liver tumors compared with the control diet mice (100% vs. 41%, P < 0.001). The diet induced steatohepatitis with pericellular fibrosis and evoked higher mRNA expression of pro-inflammatory and pro-fibrotic mediators along with enhanced hepatocyte proliferation and greater oxidative and endoplasmic reticulum stress in the liver. Moreover, long-term consumption of cholesterol-rich diet activated nuclear factor-kappa B (NF-κB) and p62/sequestosome 1 (Sqstm1)-nuclear factor erythroid 2 (NRF2) axis, enhanced fibrogenesis, and consequently accelerated hepatic tumorigenesis. In conclusion, these results demonstrate that a high-cholesterol diet facilitates liver tumorigenesis by inducing steatohepatitis, promoting hepatocyte division, and up-regulating cellular stress and pro-inflammatory NF-κB and detoxifying p62/Sqstm1-NRF2 signals. Therefore, high dietary cholesterol should be avoided in HCV-infected patients to prevent development of steatohepatitis, liver fibrosis, and HCC.
KeywordsSteatohepatitis NF-κB p62/Sqstm1-NRF2 axis Fibrogenesis Oxidative stress
α-Smooth muscle actin
B-cell leukemia/lymphoma 2-associated X protein
CCAAT/enhancer-binding protein homologous protein
Tumor necrosis factor receptor superfamily member 10b
Hepatitis C virus
HCV core gene transgenic
Liver X receptor
Non-esterified fatty acid
Nuclear factor-kappa B
NAD(P)H quinone dehydrogenase 1
Nuclear factor erythroid 2
Proliferating cell nuclear antigen
Peroxisome proliferator-activated receptor
Quantitative polymerase chain reaction
Sodium dodecyl sulfate-polyacrylamide gel electrophoresis
Standard error of the mean
Sterol regulatory element-binding protein
Total bile acid
Transforming growth factor-β1
Tumor necrosis factor-α
We appreciate Mr. Trevor Ralph for his English editorial assistance and Dr. Takero Nakajima and Dr. Ruan Guo (Shinshu University School of Medicine) for their invaluable help, advice, instruction, and encouragement. We thank Research Center for Supports to Advanced Science, Shinshu University, for technical supports and animal care. This study was partially supported by JSPS Grants-in-Aid for Scientific Research (KAKENHI Grant number 16K08734).
Design and writing the paper: NT and TA. Performing experiments: XW, NT, XH, TK, YL, FJ, and YS. Analyzing data: XW, NT, XH, TK, YL, and YS. Supervision: JN, KM, and KK. All authors read and approved the final manuscript.
The authors have declared that no financial support exists.
Compliance with ethical standards
Conflict of interest
The authors have declared that no conflict of interest exists.
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