Effect of EBV LMP1 targeted DNAzymes on cell proliferation and apoptosis

Cancer Gene Ther. 2005 Jul;12(7):647-54. doi: 10.1038/sj.cgt.7700833.

Abstract

The latent membrane protein (LMP1) encoded by Epstein-Barr virus (EBV) has been suggested to be one of the major oncogenic factors in EBV-mediated carcinogenesis. RNA-cleaving DNA enzymes are catalytic nucleic acids that bind and cleave a target RNA in a highly sequence-specific manner. In this study, we explore the potential of using DNAzymes as a therapeutic approach to EBV-associated carcinomas by targeting the LMP1 gene. In all, 13 different phosphorothioate-modified "10-23" deoxyribozymes (DNAzymes) were designed and synthesized against the LMP1 mRNA and transfected into B95-8 cells, which constitutively express the LMP1. Fluorescence microscopy was used to examine the cellular uptake and distribution in B95-8 cells. As demonstrated in Western blots, three out of 13 deoxyribozymes significantly downregulated the expression of LMP1 in B95-8 cells. These DNAzymes were shown to markedly inhibit B95-8 cell growth compared with a disabled DNAzyme and untreated controls, as determined by an alamarBlue Assay. It was further demonstrated that these DNAzymes arrested the B95-8 cells in G0/G1 using flow cytometry. Interestingly, the active DNAzymes could also downregulate the expression of Bcl-2 gene in treated cells, suggesting a close association between the LMP1 and Bcl-2 genes and their involvement in apoptosis. This was further confirmed with the result that the DNAzymes could induce the release of cytochrome c from mitochondria, which is the hallmark of the apoptosis. The present results suggest that the LMP1 may present a potential target for DNAzymes towards the EBV-associated carcinoma through cell proliferation and apoptosis pathways.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis*
  • Blotting, Western
  • Cell Line, Transformed
  • Cell Proliferation*
  • Cytochromes c / metabolism
  • DNA, Catalytic / pharmacology*
  • DNA, Single-Stranded / pharmacology*
  • Herpesvirus 4, Human / physiology*
  • Microscopy, Fluorescence
  • Mitochondria
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Viral Matrix Proteins / antagonists & inhibitors*
  • Viral Matrix Proteins / genetics
  • Viral Matrix Proteins / metabolism

Substances

  • DNA, Catalytic
  • DNA, Single-Stranded
  • EBV-associated membrane antigen, Epstein-Barr virus
  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Messenger
  • RNA-cleaving DNA 10-23
  • Viral Matrix Proteins
  • Cytochromes c