Abstract
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 language | English (US) |
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Pages (from-to) | 9771-9778 |
Number of pages | 8 |
Journal | Cancer research |
Volume | 68 |
Issue number | 23 |
DOIs | |
State | Published - Dec 1 2008 |
ASJC Scopus subject areas
- Oncology
- Cancer Research