Self-assembling peptide dimers with multifunctionalities for gene delivery systems

K. Ryu, G.J. Lee, T.-I. Kim
Seoul National University,
Korea

Keywords: gene delivery, multifunctional peptide dimer, MMP-2

Summary:

Peptides have been used in various biomedical fields including gene and drug delivery systems [1]. There are many peptide sequences which can interact with cellular molecules or components. These biological interactions of peptide represented many advantages for using gene delivery carriers targeted for cancer treatment. Representatively RGD peptide can enhance cellular recognition and attachment by integrin receptors. Some peptides also represent cell penetrating ability, pH-responsiveness, and breakage by specific enzymes. Especially, cellular penetrating peptide such as penetratin, Tat sequence, or oligoarginine have been extensively examined in gene delivery field because they can form nanosized complexes with nucleic acids due to their cationic property and possess high cellular uptake efficiency [2, 3]. Furthermore, some oligopeptides which are linked via disulfide bonds and represented bioreducibility also have been developed for gene delivery systems. They can be degraded in reductive environment such as cytosol, showing controlled release of nucleic acids and low cytotoxicity [4]. In this work, self-assembling multifunctional peptide was designed for gene delivery systems. The multifunctional peptide (MP) consists of cellular penetrating peptide moiety (R8), matrix metalloproteinase-2 (MMP-2) specific sequence (GPLGV), pH-responsive moiety (H5), and hydrophobic moiety (palmitic acid) (CR8GPLGVH5-Pal). It is expected that R8 moiety would condense pDNA into polyplex particles and facilitate the cellular uptake of the polyplexes. GPLGV is a substrate sequence of matrix metalloproteinase-2 (MMP-2), which is one of the collagenases overexpressed from several tumor cells and plays important roles in tumor progression and metastasis [5]. H5 moiety was employed for endosome buffering ability of imidazole groups to escape from endosomes after cellular uptake. Palmitic acid at C-terminal would induce micelle formation via self-assembly of the peptide by hydrophobic interaction. MP was oxidized to form multifunctional peptide dimer (MPD) by DMSO oxidation of thiols in terminal cysteine residues [6]. MPD could condense pDNA successfully at a weight ratio of 5. MPD itself could self-assemble into submicron micelle particles via hydrophobic interaction, of which critical micelle concentration is about 0.01mM. MPD showed concentration-dependent but low cytotoxicity in comparison with PEI25k. MPD polyplexes showed low transfection efficiency in HEK293 cells expressing low level of MMP-2 but high transfection efficiency in A549 and C2C12 cells expressing high level of MMP-2, meaning the enhanced transfection efficiency probably due to MMP-induced structural change of polyplexes. Bafilomycin A1-treated transfection results suggest that the transfection of MPD is mediated via endosomal escape by endosome buffering ability. These results show the potential of MPD for MMP-2 targeted gene delivery systems due to its multifunctionality.