title: Loss of nuclear PTEN in HCV-infected human hepatocytes.
abstract: BACKGROUND
  Hepatitis C virus (HCV) infection is a major risk factor for chronic hepatitis and hepatocellular carcinoma (HCC); however, the mechanism of HCV-mediated hepatocarcinogenesis is not well understood. Insufficiency of PTEN tumor suppressor is associated with more aggressive cancers, including HCC. We asked whether viral non-coding RNA could initiate oncogenesis in HCV infected human hepatocytes. The results presented herein suggest that loss of nuclear PTEN in HCV-infected human hepatocytes results from depletion of Transportin-2, which is a direct target of viral non-coding RNA, vmr11.
  
  
  METHODS
  The intracellular distribution of PTEN in HCV-infected cells was monitored by immunostaining and Western blots of nuclear and cytoplasmic proteins. Effects of PTEN depletion were examined by comparing expression arrays of uninfected cells with either HCV-infected or vmr11-transfected cells. Target genes suggested by array analyses were validated by Western blot. The influence of nuclear PTEN deficiency on virus production was determined by quantitative analysis of HCV genomic RNA in culture media of infected hepatocytes.
  
  
  RESULTS
  Import of PTEN to the nucleus relies on the interaction of Transportin-2 and PTEN proteins; we show that depletion of Transportin-2 by HCV infection or by the introduction of vmr11 in uninfected cells results in reduced nuclear PTEN. In turn, nuclear PTEN insufficiency correlates with increased virus production and the induction of γ-H2AX, a marker of DNA double-strand breaks and genomic instability.
  
  
  CONCLUSIONS
  An HCV-derived small non-coding RNA inhibits Transportin-2 and PTEN translocation to the nucleus, suggesting a direct viral role in hepatic oncogenesis.
authors: Department of Biochemistry and Molecular Medicine, The George Washington University School of Medicine, 2300 Eye Street, N.W., Washington, D.C. 20037, USA.
authors: Wenjie
authors: W
authors: Bao
authors: McKusick-Nathans Institute of Genetic Medicine, The Johns Hopkins University, Baltimore, MD, USA.
authors: Liliana
authors: L
authors: Florea
authors: Department of Biochemistry and Molecular Medicine, The George Washington University School of Medicine, 2300 Eye Street, N.W., Washington, D.C. 20037, USA.
authors: Ningbin
authors: N
authors: Wu
authors: Department of Biochemistry and Molecular Medicine, The George Washington University School of Medicine, 2300 Eye Street, N.W., Washington, D.C. 20037, USA.
authors: Zhao
authors: Z
authors: Wang
authors: Department of Biochemistry and Molecular Medicine, The George Washington University School of Medicine, 2300 Eye Street, N.W., Washington, D.C. 20037, USA.
authors: Krishna
authors: K
authors: Banaudha
authors: Current address: Metabolism Branch, NIH, Bethesda, MD, USA.
authors: Jason
authors: J
authors: Qian
authors: Molecular Virology Section, Laboratory of Molecular Microbiology, NIAID, NIH, Bethesda, MD, USA ; Current address: INSERM U1085-IRSET, Universite de Rennes1, Institut Federatif de Recherche 140, Rennes, France.
authors: Laurent
authors: L
authors: Houzet
authors: Department of Biochemistry and Molecular Medicine, The George Washington University School of Medicine, 2300 Eye Street, N.W., Washington, D.C. 20037, USA.
authors: Rakesh
authors: R
authors: Kumar
authors: Department of Biochemistry and Molecular Medicine, The George Washington University School of Medicine, 2300 Eye Street, N.W., Washington, D.C. 20037, USA.
authors: Ajit
authors: A
authors: Kumar
keywords: HCV infection; Nuclear PTEN restriction