Maintenance of the viral episome is essential for the cell survival of an Epstein-Barr virus positive gastric carcinoma cell line

Arch Pharm Res. 2009 May;32(5):729-36. doi: 10.1007/s12272-009-1512-7. Epub 2009 May 27.

Abstract

While Epstein Barr virus (EBV) is associated with about 10% of gastric carcinomas worldwide, the role of the virus in the tumorigenesis of EBV-associated gastric carcinoma (EBVaGC) is unclear. Previously, we reported that a gastric cancer cell line, SNU-719, that is naturally infected with EBV closely resembles EBVaGC. Here, we attempted to eliminate the EBV genome from SNU-719 cells to ascertain the influence of EBV in EBVaGC. Southern blotting and fluorescence in situ hybridization (FISH) showed that EBV genomes were maintained as episomes in SNU-719 cells. To remove EBV episomes, SNU-719 cells were first cultured in a hydroxyurea (HU)-containing medium for up to 6 months. Real-time polymerase chain reaction and FISH results revealed no evidence of HU-mediated EBV genome reduction, although cell growth was reduced by acute HU treatment in dose- and time-dependent manners. Two small interfering RNAs against Epstein Barr nuclear antigen 1 (EBNA1) abrogated over 90% of the ectopic EBNA1 expression in HeLa cells, but only 40% of endogenous EBNA1 expression in SNU-719 cells. Together, our data suggest that maintenance of latent EBV infection is essential for the viability of EBVaGC cells, avoiding elimination of EBV episomes from the cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Blotting, Southern
  • Carcinoma / pathology
  • Carcinoma / virology*
  • Cell Proliferation
  • Cell Survival
  • Cell Transformation, Viral / genetics*
  • Dose-Response Relationship, Drug
  • Epstein-Barr Virus Nuclear Antigens / genetics*
  • Gene Expression Regulation, Viral* / drug effects
  • HeLa Cells
  • Herpesvirus 4, Human / drug effects
  • Herpesvirus 4, Human / genetics*
  • Humans
  • Hydroxyurea / pharmacology
  • In Situ Hybridization, Fluorescence
  • Nucleic Acid Synthesis Inhibitors / pharmacology
  • Plasmids* / drug effects
  • Polymerase Chain Reaction
  • RNA Interference
  • RNA, Small Interfering / metabolism
  • Stomach Neoplasms / pathology
  • Stomach Neoplasms / virology*
  • Time Factors
  • Transfection

Substances

  • Epstein-Barr Virus Nuclear Antigens
  • Nucleic Acid Synthesis Inhibitors
  • RNA, Small Interfering
  • EBV-encoded nuclear antigen 1
  • Hydroxyurea