The Potential of Cell-Penetrating Peptides for mRNA Delivery to Cancer Cells

Abstract

In vitro transcribed mRNA for the synthesis of any given protein has shown great potential in cancer gene therapy, especially in cancer vaccines for immunotherapy. To overcome physiological barriers, such as rapid degradation by enzymatic attack and poor cellular uptake due to their large size and hydrophilic properties, many delivery carriers for mRNAs are being investigated for improving the bioavailability of mRNA. Recently, cell-penetrating peptides (CPPs) have received attention as promising tools for gene delivery. In terms of their biocompatibility and the ability to target specific cells with the versatility of peptide sequences, they may provide clues to address the challenges of conventional delivery systems for cancer mRNA delivery. In this study, optimal conditions for the CPP/mRNA complexes were identified in terms of complexation capacity and N/P ratio, and protection against RNase was confirmed. When cancer cells were treated at a concentration of 6.8 nM, which could deliver the highest amount of mRNA without toxicity, the amphipathic CPP/mRNA complexes with a size less than 200 nm showed high cellular uptake and protein expression. With advances in our understanding of CPPs, CPPs designed to target tumor tissues will be promising for use in developing a new class of mRNA delivery vehicles in cancer therapy.

Cell penetrating peptide: A potent delivery system in vaccine development

“…CPPs designed to target tumor tissues are used in developing a novel class of mRNA delivery tools in cancer therapy. Indeed, the presence of hydrophobic moieties, amino Frontiers in Pharmacology frontiersin.org acid composition, and structure of CPP play a major role in complex formation with mRNA and the transfection efficiency of cancer cells (Kim et al, 2022). This strategy is important to develop tumor cells-based vaccines against a variety of cancers.…”

“…Compared to the covalent strategy, the non-covalent method was easier to use, produce, and preserve the function of mRNA. CPPs complexed with antigen-encoding mRNA were successfully delivered to immune cells, and facilitated mRNA escape from the endosomes to the cytosol, inducing CTL responses ( Kim et al, 2022 ). The lysine- and arginine-rich cationic peptides are able to form non-covalent complexes with nucleic acids but they require in most cases a covalent conjugation to proteins, marker molecules or drugs.…”

“…CPPs have emerged as strong tools for mRNA delivery in cancer therapy. The amphipathic CPP/mRNA complexes with a size less than 200 nm showed high cellular uptake and protein expression in tumor cells ( Kim et al, 2022 ). Moreover, combinations of CPPs with lipid-based nanoparticles (LNPs) were followed in mRNA delivery ( Yokoo et al, 2022 ).…”

Lipid-Specific Direct Translocation of the Cell-Penetrating Peptide NAF-144–67 across Bilayer Membranes

“…Cell-penetrating peptides (CPPs) are short cationic oligomers that cross lipid bilayer membranes without the need of transmembrane protein channels or pumps. − Some CPPs transport molecular cargo into cells while others are cytotoxic . This class of biomolecules is of significant and long-standing interest for drug delivery, vaccine development, and cancer therapies. − Despite this interest, there are no approved CPP-based formulations for therapeutic use in humans despite wide-scale efforts to exploit these peptides for medicinal purposes. , This exposes a fundamental gap in understanding of how CPPs selectively transverse membranes at the molecular level and how this can be exploited for therapeutic purposes.…”

The Development of Cell-Penetrating Peptides for Efficient and Selective In Vivo Expression of mRNA in Spleen Tissue

“…However, the delivery of mRNA with CPPs has been less explored [ 13 , 14 ] and we are not aware of studies that compare the potential of transcript expression from pDNA vs. mRNA. Efficient in vivo transfection and subsequent protein expression is one of the limitations in further CPP use for therapeutic purposes.…”