The influence of mediators of intracellular trafficking on transgene expression efficacy of polymer-plasmid DNA complexes

Polymer-mediated gene delivery is an attractive alternative to viral vectors, but is limited by low efficacies of transgene expression. We report that polymers possess differential efficacies for transfecting closely related human prostate cancer cells, which correlates with dramatically different intracellular fate of nanoscale cargo in these cells. Sequestration of nanoscale cargo (27 nm quantum dots and 150-250 nm polyplexes) at a single location near the microtubule organizing compartment (MTOC) in PC3-PSMA human prostate cancer cells correlated with lower polymer-mediated transgene expression compared to PC3 cells, which showed distributed localization throughout the cytoplasm. We show, for the first time, that treatment with the histone deacetylase 6 (HDAC6) inhibitor tubacin, which acetylates tubulin of microtubules in the cytoplasm, abolished quantum dot and polyplex sequestration at the perinuclear recycling compartment/microtubule organizing center (PNRC/MTOC) and increased polymer-mediated transgene expression by up to forty-fold compared to cells not treated with the HDAC6 inhibitor drug. Treatment with the class I and II HDAC inhibitor trichostatin A (TSA) demonstrated similar levels of transgene expression enhancement. These results indicate that mediators of intracellular trafficking can be employed to modulate nanoparticle fate and enhance the efficacy of nanoscale therapeutics in cells. Simultaneous use of high-efficacy polymers along with mediators of intracellular trafficking is an attractive synergistic strategy for enhancing polymer-mediated transgene expression.