Construction of a Targeting Nanoparticle of 3',3″-Bis-Peptide-siRNA Conjugate/Mixed Lipid with Postinserted DSPE-PEG2000-cRGD.

The cyclic Arg-Gly-Asp (cRGD) peptides are widely used as tumor-targeting ligands due to their specific binding ability to integrin αvß3, which is overexpressed on the surface of various cancer cells and the endothelial cells of new blood vessels within tumor tissues. In this paper, the postinsertion strategy of DSPE-PEG2000-cRGD has been applied to the nanoparticles of 3',3″-bis-peptide-siRNA (pp-siRNA) encapsulated by gemini-like cationic lipid (CLD) and neutral cytosin-1-yl lipid (DNCA) from our lab. It was confirmed that the nanoparticles of pp-siRNA/CLD/DNCA/DSPE-PEG2000-cRGD (PCNR) were able to specifically target tumor cells with highly expressed integrin αvß3; moreover, it efficiently downregulated the levels of BRAF mRNA and the BRAF protein and inhibited cell proliferation in A375 cells, in comparison with the nontargeted nanocomplex of pp-siRNA/CLD/DNCA/cRAD (PCNA). The uptake pathways of PCNR are mostly dependent on CvME-mediated endocytosis and macropinocytosis in A375 cells, which could bypass lysosome or quickly lead to the lysosomal escape to reduce siRNA degradation. Finally, the biodistribution study showed that PCNR exhibited a high ability to accumulate in tumor tissues. These results suggest that the nanocomplex of PCNR is promising to be highly effective in the treatment of melanomas including their mutation.