Résumé
The development of short siRNA, has provided great hope for therapeutic targeting of specific genes responsible of patholological disorders. However their clinical application remains limited by their poor cellular uptake, low bioavail-ability, and insufficient capability to reach targets in vivo. We have designed a novel approach, based on short amphipathic peptides "NANOPEP" that promotes efficient delivery of siRNA into wide variety of mammalian cell lines and in vivo upon systemic and topical administrations. This carrier, consisting of a balance between hydrophobic and hydrophilic domains, forms stable "nanoparticles" with siRNA, through non-covalent interactions. Cellular uptake mechanism of NANOPEP/siRNA nanoparticles involves membrane potential and dynamic, which enables a rapid release of the siRNA into the cytoplasm and promotes a robust down-regulation of target mRNA. NANOPEP promotes siRNA delivery into primary cell lines and in vivo upon systemic administration without triggering any nonspecific inflammatory response. NANOPEP-carriers were applied to the delivery of siRNA targeting the cell cycle regulatory protein Cyclin B1 into cancer cells. When associated with NANOPEP, sub-nanomolar concentrations of siRNA Cyclin B1 significantly knocked down Cyclin B1 protein levels resulting in cell cycle arrest in G2 arrest and blocked cancer cell proliferation. We have validated the therapeutic potential of this strategy for cancer treatment by targeting cyclin B1 in various mouse tumour models and demonstrate that NANOPEP-mediated delivery of cyclin B1 siRNA prevents tumour growth in vivo following systemic intravenous injection. Moreover, functio-nalization of NANOPEP particles with other chemical groups or biological moieties can be applied to generate formulations to target specific cell types or tissues which can be of a major interest for future development. Given the biological response yielded through this approach, we propose that non-covalent, peptide-based delivery technologies hold a strong promise for therapeutic administration of siRNA.