Down-regulation of EBV-LMP1 radio-sensitizes nasal pharyngeal carcinoma cells via NF-κB regulated ATM expression

PLoS One. 2011;6(11):e24647. doi: 10.1371/journal.pone.0024647. Epub 2011 Nov 9.

Abstract

Background: The latent membrane protein 1 (LMP1) encoded by EBV is expressed in the majority of EBV-associated human malignancies and has been suggested to be one of the major oncogenic factors in EBV-mediated carcinogenesis. In previous studies we experimentally demonstrated that down-regulation of LMP1 expression by DNAzymes could increase radiosensitivity both in cells and in a xenograft NPC model in mice.

Results: In this study we explored the molecular mechanisms underlying the radiosensitization caused by the down-regulation of LMP1 in nasopharyngeal carcinoma. It was confirmed that LMP1 could up-regulate ATM expression in NPCs. Bioinformatic analysis of the ATM ptomoter region revealed three tentative binding sites for NF-κB. By using a specific inhibitor of NF-κB signaling and the dominant negative mutant of IkappaB, it was shown that the ATM expression in CNE1-LMP1 cells could be efficiently suppressed. Inhibition of LMP1 expression by the DNAzyme led to attenuation of the NF-κB DNA binding activity. We further showed that the silence of ATM expression by ATM-targeted siRNA could enhance the radiosensitivity in LMP1 positive NPC cells.

Conclusions: Together, our results indicate that ATM expression can be regulated by LMP1 via the NF-κB pathways through direct promoter binding, which resulted in the change of radiosensitivity in NPCs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Ataxia Telangiectasia Mutated Proteins
  • Blotting, Western
  • Carcinoma
  • Cell Cycle Proteins / genetics
  • Cell Cycle Proteins / metabolism*
  • Cell Line, Tumor
  • Computational Biology
  • DNA, Catalytic / metabolism
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Electrophoretic Mobility Shift Assay
  • Female
  • Flow Cytometry
  • Humans
  • Immunochemistry
  • Mice
  • Mice, Inbred BALB C
  • Mice, Nude
  • NF-kappa B / antagonists & inhibitors
  • NF-kappa B / metabolism*
  • Nasopharyngeal Carcinoma
  • Nasopharyngeal Neoplasms / genetics
  • Nasopharyngeal Neoplasms / metabolism*
  • Nasopharyngeal Neoplasms / radiotherapy*
  • Nitriles / pharmacology
  • Promoter Regions, Genetic / genetics
  • Protein Binding
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism*
  • RNA, Small Interfering / genetics
  • RNA, Small Interfering / physiology
  • Real-Time Polymerase Chain Reaction
  • Signal Transduction / drug effects
  • Signal Transduction / genetics
  • Sulfones / pharmacology
  • Tumor Suppressor Proteins / genetics
  • Tumor Suppressor Proteins / metabolism*
  • Viral Matrix Proteins / genetics
  • Viral Matrix Proteins / metabolism*
  • X-Rays

Substances

  • 3-(4-methylphenylsulfonyl)-2-propenenitrile
  • Cell Cycle Proteins
  • DNA, Catalytic
  • DNA-Binding Proteins
  • EBV-associated membrane antigen, Epstein-Barr virus
  • NF-kappa B
  • Nitriles
  • RNA, Small Interfering
  • Sulfones
  • Tumor Suppressor Proteins
  • Viral Matrix Proteins
  • ATM protein, human
  • Ataxia Telangiectasia Mutated Proteins
  • Atm protein, mouse
  • Protein Serine-Threonine Kinases