Caged siRNAs with Single cRGD Modification for Photoregulation of Exogenous and Endogenous Gene Expression in Cells and Mice

RNA interference (RNAi) mediated gene silencing holds significant promise in gene therapy. It is very important to manually regulate the activity of small interference RNAs (siRNAs) in the controllable mode. Here, we designed and synthesized a series of caged siRNAs through bioconjugation of cyclo­(Arg-Gly-Asp-d-Phe-Lys) (cRGD) peptide to the 5′ end of siRNA through a photolabile linker. These cRGD modified caged siRNAs allowed for precise light-regulation of gene expression of two exogenous reporter genes (firefly luciferase and green fluorescent protein, GFP) and an endogenous gene (the mitosis motor protein, Eg5) in the integrin α_vβ₃ positive cells. This kind of bioconjugate further enabled photochemical activation of siRNA activity, and the target gene silencing was successfully achieved in tumor-bearing mice by intratumoral injection. This study also suggested that photomodulation of target gene expression using single cRGD caged siRNA at the 5′ end of antisense strand RNA inhibited siRNA activity probably due to three factors: (1) trapping of cRGD modified siRNA in endosome and lysosome, (2) the steric hindrance of cRGD, (3) the binding of cRGD to its corresponding receptor

Vitamin E‑Labeled Polyethylenimine for <i>in vitro</i> and <i>in vivo</i> Gene Delivery

A series of Vitamin E (vitE)-labeled PEIs (PEI-vitE_<i>n</i>) were synthesized and showed excellent complexation ability with plasmid DNA (pDNA). The cellular uptake of PEI-vitE_<i>n</i>/pDNA complexes was greatly enhanced with the increase of vitE labeling, which is much better than that of control PEI25 in three different cell lines. PEI-vitE₆ showed the best performance in <i>gfp</i> pDNA delivery and following GFP expression in HEK-293A cells. In addition, <i>in vivo</i> gene delivery in living mice also confirmed that PEI-vitE₆ showed low toxicity and efficiently delivered <i>gfp</i> pDNA to the cells of liver and lung tissues for gene expression