Amphiphilic Block Copolymers Enhance Cellular Uptake and Nuclear Entry of Polyplex-Delivered DNA

This work for the first time demonstrates that synthetic polymers enhance uptake and nuclear import of plasmid DNA (pDNA) through the activation of cellular trafficking machinery. Nonionic block copolymers of poly(ethylene oxide) and poly(propylene oxide), Pluronics, are widely used as excipients in pharmaceutics. We previously demonstrated that Pluronics increase the phosphorylation of I kappa B and subsequent NF kappa B nuclear localization as well as upregulate numerous NF kappa B-related genes. In this study, we show that Pluronics enhance gene transfer by pDNA/polycation complexes (polyplexes) in a promoter-dependent fashion. Addition of Pluronic P123 or P85 to polyethyleneimine-based polyplexes had little effect on polyplex particle size but significantly enhanced pDNA cellular uptake, nuclear translocation, and gene expression in several cell lines. When added to polyplex-transfected cells after transfection, Pluronics enhanced nuclear import of pDNA containing NF kappa B binding sites, but have no effect on import of pDNA without these sites. Altogether, our studies suggest that Pluronics rapidly activate NF kappa B, which binds cytosolic pDNA that possesses promoters containing NF kappa B binding sites and consequently increase nuclear import of pDNA through NF kappa B nuclear translocation.