Tissue distribution of liposome-mediated epidermal growth factor receptor antisense gene therapy

Abstract

Despite the widespread use of liposome-mediated gene transfer in cancer therapy protocols, little is known about the tissue distribution of intralesionally administered DNA. We have previously shown that antisense gene therapy targeting the epidermal growth factor receptor (EGFR) inhibited tumor growth in a human head and neck squamous cell carcinoma (HNSCC) xenograft model. Further investigation demonstrated lack of systemic toxicity with intramuscular or intratumoral administration of this liposomal-DNA complex. In the present study, we compared two approaches to determine the presence of exogenous DNA in the plasma and tissues of mice treated with intramuscular injection of EGFR antisense gene therapy. PCR analysis using genomic DNA plus plasmid DNA as template was 83-fold more sensitive than PCR using a mixture of total RNA and plasmid DNA as template. With the more sensitive method (able to detect fewer than 500 molecules of EGFR antisense DNA in 1 mg of genomic DNA), foreign DNA was detected in all organs up to 1 month following a single injection. In contrast, using RNA plus plasmid DNA as template, exogenous DNA was only detected at the injection site at 1 week, and was undetectable at 1 month. Optical imaging studies demonstrated plasmid DNA only at the injection site. Although less sensitive than PCCR, Southern blot hybridization showed no evidence of integration of foreign DNA into the host genome in vitro or in vivo. These results emphasize the importance of defining the assays used to detect foreign DNA and suggest that the ability to detect intralesionally administered liposomal gene therapy, in organs distant from the injection site, is directly correlated with the sensitivity of the method employed.

Novel chitosan derivative nanoparticles enhance the immunogenicity of a DNA vaccine encoding hepatitis B virus core antigen in mice

“…At the same time, naked DNA injected with the same dosage would be degraded more rapidly than the nanoparticle formulations and its expression would not be detected as long as those associated DNA were. These observations were in accordance with the reports that extracellular DNA was rapidly degraded and cleared within several hours after immunization [26,27]. It seems reasonable to hypothesize that nanoparticles may promote immunity by prolonging the release of the plasmid encoding the target antigen and preventing its degradation through encapsulation into a complex structure of polymeric materials [28,29].…”

Intratumoral Epidermal Growth Factor Receptor Antisense DNA Therapy in Head and Neck Cancer: First Human Application and Potential Antitumor Mechanisms

“…15 Similarly, antitumor effects were seen when EGFR AS gene therapy (referred to simply as EGFR AS) was safely administered in a nude mouse xenograft model. [16][17][18] This study was designed to determine the toxicity and safety of intratumoral EGFR AS in patients with SCCHN, and a secondary objective was to examine the effects of EGFR AS treatment on candidate biomarkers in tumor specimens.…”

“…18 The human U6 promoter and EGFR AS sequence were inserted into a modified pNGVL vector. Plasmid DNA was produced under good manufacturing practice conditions at the Center for Biomedicine and Genetics at the City of Hope (Duarte, CA) to City of Hope's Master File BB-MF-9778.…”

The Current State of Head and Neck Cancer Gene Therapy

“…THOMAS AND GRANDIS (Nagayasu et al, 1999 (Thomas et al, 2003). Plasmid DNA persisted in various tissues, including the injection site, for 1 month.…”