Amphiphilic Peptides for Efficient siRNA Delivery

Abstract

A number of amphiphilic cyclic peptides—[FR]4, [WR]5, and [WK]5—containing hydrophobic and positively-charged amino acids were synthesized by Fmoc/tBu solid-phase peptide methods and evaluated for their efficiency in intracellular delivery of siRNA to triple-negative breast cancer cell lines, MDA-MB-231 and MDA-MB-468, in the presence and absence of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE). Among the peptides, [WR]5, which contains alternate tryptophan (W) and arginine (R) residues, was found to be the most efficient in the delivery of siRNA by improving the delivery by more than 3-fold when compared to other synthesized cyclic peptides that were not efficient. The data also showed that co-formulation of [WR]5 with lipid DOPE significantly enhanced the efficiency of siRNA delivery by up to ~2-fold compared to peptide alone. Based on the data indicating the efficiency of [WR]5 in siRNA delivery, peptides containing arginine residues on the ring and tryptophan residues on the side chain, [R6K]W6 and [R5K]W5, were also evaluated, and demonstrated improved delivery of siRNA. The presence of DOPE again enhanced the siRNA delivery in most cases. [WR]5, [R5K]W5, and [R6K]W6 did not show any significant toxicity in MDA-MB-231, MDA-MB-468, and AU565 WT cells at N/P ratios of 20:1 or less, in the presence and absence of DOPE. Silencing of kinesin spindle protein (KSP) and Janus kinase 2 (JAK2) was evaluated in MDA-MB-231 cells in the presence of the peptides. The addition of DOPE significantly enhanced the silencing efficiency for all selected peptides. In conclusion, peptides containing tryptophan and arginine residues were found to enhance siRNA delivery and to generate silencing of targeted proteins in the presence of DOPE.

Cyclic Peptide-Gadolinium Nanocomplexes as siRNA Delivery Tools

“…Multiple elements, including positively charged arginine amino acids in the structure of the peptide and the negatively charged phosphates of the siRNA could be involved in the binding affinity. The results obtained are consistent with the previous reports of tryptophan-and arginine-containing peptides from our group [40,41].…”

A gold mine for drug discovery: Strategies to develop cyclic peptides into therapies

“…According to the sequences of the synthetic cyclic CPPs, most of them are rich in arginine, tryptophan, lysine, or histidine residues. For example, the peptides [WR] n ( n = 3 − 9), exhibit significant cell permeability and have been developed to deliver anti‐HIV drugs or small interfering RNA molecules (siRNA) . The cyclic CPPs derived from natural products like disulfide‐rich cyclic CPPs, have also been studied by various research groups.…”

Suppression of Human Coronavirus 229E Infection in Lung Fibroblast Cells via RNA Interference

“…Herein, we report on the former approach due to a lower chance of complications that could result from silencing host proteins and controversy over the efficiency of targeting proteins such as angiotensin-converting enzyme 2 (ACE2). We have previously reported efficient small interfering RNA (siRNA) delivery to cancer cells via specifically designed polymers (Aliabadi et al, 2011;Aliabadi et al, 2013;Aliabadi et al, 2020) and cell-penetrating peptides (Do et al, 2017;Mozaffari et al, 2019). We also recently reported a novel delivery system called Peptide/Lipid-Associated Nucleic Acids (PLANAs), which is based on the incorporation of specifically designed cell-penetrating peptides in a multi-component nanoparticle (Hall et al, 2021a) (United States patent application number 17170785).…”