Targeting CCl4-induced liver fibrosis by RNA interference - mediated inhibition of Cyclin E1 in mice

Abstract

Initiation and progression of liver fibrosis requires proliferation and activation of resting hepatic stellate cells (HSC). Cyclin E1 (CcnE1) is the regulatory subunit of the Cyclin-dependent Kinase 2 (Cdk2) and controls cell cycle re-entry. We have recently shown that genetic inactivation of CcnE1 prevents activation, proliferation and survival of HSC and protects from liver fibrogenesis. The aim of the present study was to translate these findings into pre-clinical applications using an RNAi-based approach. CcnE1-siRNA efficiently inhibited CcnE1 gene expression in murine and human HSC cell lines and in primary HSCs resulting in diminished proliferation and increased cell death. In C57BL/6 wildtype (WT) mice, delivery of stabilized siRNA using a liposome-based carrier targeted approximately 95% of HSC, 70% of hepatocytes, and 40% of CD45+ cells after single injection. Acute CCl₄-mediated liver injury in WT mice induced endogenous CcnE1 expression and proliferation of surviving hepatocytes and non-parenchymal cells including CD45+ leukocytes. Pre-treatment with CcnE1-siRNA reverted CcnE1 induction to baseline levels of healthy mice, which was associated with reduced liver injury, diminished proliferation of hepatocytes, leukocytes and attenuated overall inflammatory response. For induction of liver fibrosis, WT mice were challenged with CCl₄ for 4-6 weeks. Co-treatment with CcnE1-siRNA once a week was sufficient to continuously block CcnE1 expression and cell cycle activity of hepatocytes and non-parenchymal cells resulting in significantly ameliorated liver fibrosis and inflammation. Importantly, CcnE1-siRNA also prevented progression of liver fibrosis if applied after onset of chronic liver injury.

Conclusion: Therapeutic targeting of CcnE1 in vivo using RNAi is feasible and has high anti-fibrotic activity. This article is protected by copyright. All rights reserved.

http://ift.tt/2pOS7U3