Inhibition of repair of radiation-induced DNA damage enhances gene expression from replication-defective adenoviral vectors

Mohan Hingorani, Christine L. White, Andrew Merron, Inge Peerlinck, Martin E. Gore, Andrew Slade, Simon D. Scott, Christopher M. Nutting, Hardev S. Pandha, Alan A. Melcher, Richard G. Vile, Georges Vassaux, Kevin J. Harrington

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Radiation has been shown to up-regulate gene expression from adenoviral vectors in previous studies. In the current study, we show that radiation-induced dsDNA breaks and subsequent signaling through the mitogen-activated protein kinase (MAPK) pathway are responsible, at least in part, for this enhancement of transgene expression both in vitro and in vivo. Inhibitors of ataxia-telangiectasia-mutated, poly(ADP-ribose) polymerase-mutated, and DNA-dependent protein kinase (DNA-PK)-mediated DNA repair were shown to maintain dsDNA breaks (γH2AX foci) by fluorescence-activated cell sorting and microscopy. Inhibition of DNA repair was associated with increased green fluorescent protein (GFP) expression from a replication-defective adenoviral vector (Ad-CMV-GFP). Radiation-induced up-regulation of gene expression was abrogated by inhibitors of MAPK (PD980059 and U0126) and phosphatidylinositol 3-kinase (LY294002) but not by p38 MAPK inhibition. A reporter plasmid assay in which GFP was under the transcriptional control of artificial Egr-1 or cytomegalovirus promoters showed that the DNA repair inhibitors increased GFP expression only in the context of the Egr-1 promoter. In vivo administration of a water-soluble DNA-PK inhibitor (KU0060648) was shown to maintain luciferase expression in HCT116 xenografts after intratumoral delivery of Ad-RSV-Luc. These data have important implications for therapeutic strategies involving multimodality use of radiation, targeted drugs, and adenoviral gene delivery and provide a framework for evaluating potential advantageous combinatorial effects.

Original languageEnglish (US)
Pages (from-to)9771-9778
Number of pages8
JournalCancer research
Issue number23
StatePublished - Dec 1 2008

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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