title: Oxidative stress induces anti-hepatitis C virus status via the activation of extracellular signal-regulated kinase.
abstract: Recently, we reported that beta-carotene, vitamin D(2), and linoleic acid inhibited hepatitis C virus (HCV) RNA replication in hepatoma cells. Interestingly, in the course of the study, we found that the antioxidant vitamin E negated the anti-HCV activities of these nutrients. These results suggest that the oxidative stress caused by the three nutrients is involved in their anti-HCV activities. However, the molecular mechanism by which oxidative stress induces anti-HCV status remains unknown. Oxidative stress is also known to activate extracellular signal-regulated kinase (ERK). Therefore, we hypothesized that oxidative stress induces anti-HCV status via the mitogen activated protein kinase (MAPK)/ERK kinase (MEK)-ERK1/2 signaling pathway. In this study, we found that the MEK1/2-specific inhibitor U0126 abolished the anti-HCV activities of the three nutrients in a dose-dependent manner. Moreover, U0126 significantly attenuated the anti-HCV activities of polyunsaturated fatty acids, interferon-gamma, and cyclosporine A, but not statins. We further demonstrated that, with the exception of the statins, all of these anti-HCV nutrients and reagents actually induced activation of the MEK-ERK1/2 signaling pathway, which was inhibited or reduced by treatment not only with U0126 but also with vitamin E. We also demonstrated that phosphorylation of ERK1/2 by cyclosporine A was attenuated with N-acetylcysteine treatment and led to the negation of inhibition of HCV RNA replication. We propose that a cellular process that follows ERK1/2 phosphorylation and is specific to oxidative stimulation might lead to down-regulation of HCV RNA replication.
  
  
  CONCLUSIONS
  Our results demonstrate the involvement of the MEK-ERK1/2 signaling pathway in the anti-HCV status induced by oxidative stress in a broad range of anti-HCV reagents. This intracellular modulation is expected to be a therapeutic target for the suppression of HCV RNA replication.
authors.affiliation: Department of Tumor Virology, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama, Japan.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Yano
authors.forename: Masanori
authors.initials: M
authors.lastname: Ikeda
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Abe
authors.forename: Yoshinari
authors.initials: Y
authors.lastname: Kawai
authors.forename: Misao
authors.initials: M
authors.lastname: Kuroki
authors.forename: Kyoko
authors.initials: K
authors.lastname: Mori
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Dansako
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Ariumi
authors.forename: Shougo
authors.initials: S
authors.lastname: Ohkoshi
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Aoyagi
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kato
mesh_terms: D002070:Butadienes / Q000494:pharmacology; D045744:Cell Line, Tumor; D004789:Enzyme Activation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D016174:Hepacivirus / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D019787:Linoleic Acid / Q000494:pharmacology; D048369:MAP Kinase Kinase 1 / Q000037:antagonists & inhibitors; D048370:MAP Kinase Kinase 2 / Q000037:antagonists & inhibitors; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009570:Nitriles / Q000494:pharmacology; D018384:Oxidative Stress / Q000502:physiology*; D012367:RNA, Viral / Q000378:metabolism; D015398:Signal Transduction; D014810:Vitamin E / Q000494:pharmacology
chemical_list: D002070:Butadienes; D009570:Nitriles; D012367:RNA, Viral; C113580:U 0126; D014810:Vitamin E; D004815:Epidermal Growth Factor; D019787:Linoleic Acid; D006861:Hydrogen Peroxide; D048049:Extracellular Signal-Regulated MAP Kinases; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D048370:MAP Kinase Kinase 2