Optimizing RNA nanoparticles size and shape for enhancing cancer targeting and treatment

Guo’s previous studies on RNA nanoparticles revealed a high efficiency in cell targeting and entry by receptor-mediated endocytosis. As with any siRNA or miRNA, RNA nanoparticles must provide efficient cellular internalization, escape from endocytic vesicles, and release siRNA/miRNA in the cytosol. Although the endosome escape using small anti-miRNA LNA fragment in RNA nanoparticle delivery has been successful and cancer regression has been found to be efficient, the efficacy of endosome escape of siRNA in RNA nanoparticles is still unknown since cancer regression after siRNA delivery via receptor mediated endocytosis is relatively low. Our hypothesis is that different cellular endocytosis or internalization pathways govern subsequent intracellular processing and endosome escape efficiency of RNA nanoparticles (Fig. 1). Our studies and many reports from literature have revealed that RNA or DNA delivered to cells via liposome, exosome, antibody, polymer or transfected by lipofactamine expressed high functionality. It is expected that the RNA or DNA delivered by lipids can enter the cytosol since the lipid will assist their trafficking through the endosome membranes. Polymer can offer the proton sponge effect to break the endosome, while the Fc domain of IgG can help antibody to recycle through the endosome membrane. RNA nanoparticles are guided to specific cells using ligands to recognize receptors displayed on target cells. Such receptors are typically internalized by clathrinor caveolin-dependent pathways. Therefore, the presence of a specific targeting ligand will impact the pathway of delivery and intracellular activity. AIM 1 is to elucidate the pathway of internalization and intracellular trafficking mechanisms of endocytic uptake, the subsequent intracellular trafficking, the efficacy of endosome escape and the subsequent gene silencing efficiency of RNA nanoparticles.