Studies of direct intratumoral gene transfer using cationic lipid- complexed plasmid DNA

Paul R. Clark, Alison T. Stopeck, Marilyn Ferrari, Suezanne E. Parker, Evan M. Hersh

Research output: Contribution to journalArticle

30 Scopus citations

Abstract

Cationic lipid-mediated gene transfer is a safe and effective means of delivering potent immunomodulatory cytokines directly into tumors. This approach avoids undesirable side effects, including systemic toxicities. To investigate key factors affecting intratumoral (i.t.) gene transfer, cationic lipid-DNA complexes were injected into subcutaneous human melanoma tumors in severe combined immunodeficient mice. Animals received i.t. injections of VR1103, a DNA plasmid encoding the gene for human interleukin-2 (IL-2), either alone or complexed with the cationic lipid N-(1 -(2,3- dimyristyloxypropyl)-N,N-dimethyl-(2-hydroxyethyl) ammonium bromide/dioleoyl phosphatidylethanolamine (DMRIE/DOPE). Tumors were subcultured and supernatants were tested for IL-2 secretion by enzyme-linked immunosorbent assay. IL-2 secretion was consistently higher when lipid:DNA (L:D) complexes were formulated at high L:D ratios (wt/wt), and IL-2 transgene expression increased in a DNA dose-dependent manner. A comparison of naked plasmid and lipid-complexed DNA revealed that lipid complexes were more effective for i.t. gene transfer. Using an enhanced green fluorescent protein reporter plasmid and flow cytometry, i.t. transfection efficiency was 1.74% (± 1.08%). Tumor injection technique, including injection volume and location, had a limited impact on i.t. gene transfer. These results indicate that the formulation and dosage of cationic L:D complexes, but not injection technique, play a key role in determining the level of i.t. transgene expression.

Original languageEnglish (US)
Pages (from-to)853-860
Number of pages8
JournalCancer gene therapy
Volume7
Issue number6
DOIs
StatePublished - Jan 1 2000

Keywords

  • Cationic lipids
  • Interleukin-2
  • Intratumoral
  • Plasmid DNA
  • Severe combined immunodeficient

ASJC Scopus subject areas

  • Molecular Medicine
  • Molecular Biology
  • Cancer Research

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