Maintenance of the viral episome is essential for the cell survival of an Epstein-Barr virus positive gastric carcinoma cell line.
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.
Oh
Sang Taek
ST
Department of Biomedical Sciences, Catholic University of Korea, Seoul, 137-701, Korea.
Kim
Myungshin
M
Lee
Suk Kyeong
SK
D015139:Blotting, Southern; D002277:Carcinoma / Q000473:pathology / Q000821:virology*; D049109:Cell Proliferation; D002470:Cell Survival; D002472:Cell Transformation, Viral / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D019309:Epstein-Barr Virus Nuclear Antigens / Q000235:genetics*; D015967:Gene Expression Regulation, Viral / Q000187:drug effects; D006367:HeLa Cells; D004854:Herpesvirus 4, Human / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology; D017404:In Situ Hybridization, Fluorescence; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D010957:Plasmids / Q000187:drug effects; D016133:Polymerase Chain Reaction; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D013274:Stomach Neoplasms / Q000473:pathology / Q000821:virology*; D013997:Time Factors; D014162:Transfection
D019309:Epstein-Barr Virus Nuclear Antigens; D019384:Nucleic Acid Synthesis Inhibitors; D034741:RNA, Small Interfering; C417029:EBV-encoded nuclear antigen 1; D006918:Hydroxyurea