Complexation to Cationic Microspheres of Double-Stranded Peptide Nucleic Acid-DNA Chimeras Exhibiting Decoy Activity.

The major aim of this paper was to determine whether cationic microspheres (CM), consisting of the permeable polymer Eudragit^® RS 100 plus the cationic surfactant dioctadecyl-dimethyl-ammonium bromide (DDAB₁₈), could bind to double-stranded peptide nucleic acid PNA-DNA-PNA (PDP) chimeras exhibiting decoy activity against NF-κB transcription factors. Microspheres were produced by the ‘solvent evaporation method’ and centrifugation at 500, 1,000 and 3,000 rpm to obtain different-sized microparticles. Microsphere morphology, size and size distribution were determined by optical and electron microscopy observations. In order to determine their binding activity, double-stranded DNA-based and PDP-based decoy molecules were incubated with different amounts of microparticles in the presence of 100 ng of either ³²P-labeled DNA-DNA or DNA-PDP hybrid molecules or cold PDP-PDP hybrids. The complexes were analyzed by agarose gel electrophoresis. The resistance of ³²P-labeled DNA-DNA and DNA-PDP molecules in the presence of serum or cellular extracts was evaluated after binding to CM by gel electrophoresis analysis. DDAB₁₈ Eudragit RS 100 microspheres are able to bind to DNA-PDP and PDP-PDP hybrids, to deliver these molecules to target cells and to protect DNA-PDP molecules from enzymatic degradation in simulated biological fluids. In addition, when assayed in ex vivo conditions, DDAB₁₈ Eudragit RS 100 microspheres exhibited low toxicity. The results presented in this paper demonstrate that CM can be considered suitable formulations for pharmacogenomic therapy employing double-stranded PDP chimeras. Copyright © 2004 National Science Council, ROC and S. Karger AG, Basel [ABSTRACT FROM AUTHOR]