Background MicroRNAs (miRNAs) are important in hepatic pathophysiology and the development of liver cancer.
Objective To explore miRNAs that are regulated with the progression of liver fibrosis caused by chronic liver disease.
Design The regulated miRNAs in human livers infected with hepatitis C virus were identified by microarray analysis. Their expression in human livers with non-alcoholic steatohepatitis, mouse livers from two fibrosis models and cultured stellate cells was validated by real-time RT-PCR. The regulation of miR-222 expression in stellate cells by nuclear factor kappa B (NF-κB) was assayed. Finally, the effects of an miR-222 precursor or inhibitor on the expression of cyclin-dependent kinase inhibitor 1B (CDKN1B) and the growth of LX-2 cells were determined.
Results It was found that miR-199a-5p/199a-3p and miR-221/222 were upregulated in the human liver in a fibrosis progression–dependent manner. Among these miRNAs, miR-221/222 were upregulated in LX-2 cells and increased during the course of culture-dependent activation of mouse primary stellate cells, in a manner similar to the expression of α1(I) collagen and α-smooth muscle actin mRNAs. The expression of miR-221/222 increased in mouse models of liver fibrosis. In contrast, an NF-κB inhibitor significantly suppressed the miR-222 induction that was stimulated in culture by transforming growth factor α or tumour necrosis factor α. Although overexpression or downregulation of miR-222 failed to regulate the growth of LX-2 cells, miR-222 bound to the CDKN1B 3′UTR and regulated the expression of the corresponding protein.
Conclusion miR-221/222 may be new markers for stellate cell activation and liver fibrosis progression.
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- Chronic hepatitis
- type I collagen
- α-smooth muscle actin
- nuclear factor kappa B
- cyclin-dependent kinase
- 3' untranslated region
- hepatic stellate cell
- molecular biology
- molecular carcinogenesis
- nonalcoholic steatohepatitis
- hepatic fibrosis
- hepatic stellate cells
- liver regeneration
- liver cirrhosis
Funding NK was supported by a grant-in-aid for scientific research from the Japan Society for the Promotion of Science (JSPS) (No 21390232; 2009–2011), a grant from the Ministry of Health, Labour and Welfare of Japan (2008–2010) and a Thrust Area Research Grant from Osaka City University (2008–2011). TO was supported by a grant-in-aid for scientific research from the JSPS (No 22790666; 2010–2011).
Competing interests None.
Ethics approval Ethics approval was provided by Osaka City University Medical School.
Provenance and peer review Not commissioned; externally peer reviewed.
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