Design and Evaluation of Endosomolytic Biocompatible Peptides as Carriers for siRNA Delivery

Abstract

Gene therapy using RNA interference (RNAi) technology has been explored to treat cancers, by regulating the expression of oncogene. However, even though small interfering RNA (siRNA), which triggers RNAi, may have great therapeutic potential, efforts at using them in vivo have been hampered by the difficulty of effective and safe delivery into cells of interest. In this study, to develop a safe and efficient carrier for in vitro and in vivo siRNA delivery, we designed a peptide library. These peptides are improved variants of a known peptide based siRNA carrier C6. All the modifications improved the transfection efficiency of C6 to some degree. After completing prescreening for activity, several promising candidates were used for further evaluation. Selected peptides C6M3 and C6M6 could form stable complexes with siRNA. These complexes could be greatly uptaken by cells and showed a punctate perinuclear distribution. Moreover, peptide/siRNA complexes achieved high transfection efficiency in vitro without inducing substantial cytotoxicity. We have validated the therapeutic potential of this strategy for cancer treatment by targeting Bcl-2 gene in mouse tumor models, and demonstrated that tumor growth was inhibited. In order to address possible immune side effects of these peptide carriers, biocompatibility study in terms of complement activation and cytokine activation assay were carried out, whereas none of the peptides induced such effects. In conclusion, these results support the potential of these peptides as therapeutic siRNA carrier.

Synthesis, Characterization, and Biological Activity of Aminated Zymosan

“…All images were taken with a resolution of 512 × 512 pixels on the 20 × 20 μm scale for ZM and 10 × 10 μm scale for ZMA. 58 Cell Viability of ZM and ZMA. The biocompatibility of ZM and ZMA toward Raw 264.7 cells was analyzed by the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) MTT assay.…”

“…The surface of the glass slide was analyzed using a Park systems X-100 atomic force microscope at room temperature under the noncontact mode to determine the microstructures. All images were taken with a resolution of 512 × 512 pixels on the 20 × 20 μm scale for ZM and 10 × 10 μm scale for ZMA …”

Peptide-Based Nanoparticles for Therapeutic Nucleic Acid Delivery

“…To further promote the endosomal escape by the pH-buffering effect of protonable groups (pH sponge effect), Chen and colleagues introduced histidine residues into peptide of C6 and C6M1, creating seven new analogues (C6M2-C6M8) with histidine substitutions [52]. Furthermore, the peptides C6M6 to C6M8 were designed with an additional glycine residue at the N-terminal end.…”

Nucleic Acid Bioconjugates in Cancer Detection and Therapy

“…Tumor cell surface receptor targeting ligands or cancer‐targeting peptides (CTPs) have also been applied for specific siRNA delivery in cancer cells . Multivalent cRGD peptides have been conjugated to siRNA for targeting the integrin receptors overexpressed on tumors.…”