Z Gastroenterol 2013; 51 - P_5_37
DOI: 10.1055/s-0032-1332151

Down regulation of osteopontin interferes with HCV replication by inhibition of WNT signalling in vitro

C Loscher 1, R Bartenschlager 2, V Lohmann 2, G Tiegs 1, G Sass 1
  • 1University Medical Center Hamburg-Eppendorf, Institute of Experimental Immunology and Hepatology,, Hamburg, Germany
  • 2University of Heidelberg, Department of Infectious Diseases, Molecular Virology, Heidelberg, Germany

Background and Aims: Osteopontin (OPN) is a secreted protein which is expressed in bone, immune cells and malignant cells. OPN is involved in migration and cell fusion and has been found upregulated in cirrhosis patients with HBV infection. We investigated relations between OPN and HCV replication as well as underlying mechanisms.

Methods: For in vitro experiments the HCV replicon system expressing HCV genes NS3 to NS5B alone (Huh5–15) or in combination with firefly luciferase (LucUbiNeo-ET) was used. Knockdown of OPN expression was achieved by transfection of siRNA. Gene expression was measured by real time RT-PCR and Western Blot analysis. OPN levels were also measured using a luciferase reporter assay. Wnt pathway activity was measured by a reporter assay for beta catenin related transcription (CRT assay) and by real time RT-PCR.

Results: Compared to the replicon system background cell line Huh7, OPN expression was found to be enhanced in both HCV replicon cell lines. Knockdown of OPN expression by siRNA interfered with HCV replication. Wnt pathway activity, which is associated with higher HCV replication, was found to be reduced upon OPN knockdown by siRNA transfection, using CRT assays and real time RT-PCR for wnt target genes.

Conclusions: HCV replication seems to induce OPN expression, which in turn activates wnt signalling and provides a replication advantage for the virus. OPN might represent a novel target to interfere with HCV replication.