RAGE-binding peptide-conjugated polyethylenimine as a dual-functional carrier: A RAGE-mediated gene carrier and an anti-angiogenic reagent

Intranasal delivery of self-assembled nanoparticles of therapeutic peptides and antagomirs elicits anti-tumor effects in an intracranial glioblastoma model

MicroRNA-21 (miR-21) is involved in the progression of glioblastoma through inhibition of pro-apoptotic genes. Antisense RNA against miR-21 (antagomir-21) has been developed as a potential therapeutic reagent for the treatment of glioblastoma. The receptor for advanced glycation end-products (RAGE) is also involved in the progression of glioblastoma through induction of angiogenic factors. Therefore, RAGE-antagonist peptide (RAP) is proposed to be an anti-tumor reagent. In this study, self-assembled nanoparticles were produced solely with therapeutic agents, antagomir-21 and RAP, with no additional carrier. The therapeutic effects of the nanoparticles by intranasal delivery were evaluated in intracranial glioblastoma animal models. First, physical characterizations such as size/zeta-potential study, scanning electron microscopy, and gel retardation assays showed that antagomir-21 and RAP formed stable nanoparticles without any additional reagents. The ratio between antagomir-21 and RAP was optimized by an in vitro cellular uptake study. The antagomir-21/RAP nanoparticles were administrated intranasally in the intracranial glioblastoma animal models to bypass the blood-brain-barrier. As a result, the nanoparticles reduced the miR-21 levels in tumors. Inhibition of miR-21 by the nanoparticles induced the expression of pro-apoptotic genes, such as PTEN and PDCD4, which enhanced tumor cell apoptosis. In addition, the expression of RAGE was suppressed by the nanoparticles, resulting in decreased levels of vascular endothelial growth factor in the tumor. The reduction of CD31-positive endothelial cells confirmed the anti-angiogenic effects of the nanoparticles. The results indicate that the intranasal delivery of the self-assembled nanoparticles of antagomir-21 and RAP is an efficient treatment of glioblastoma.

A dual-functional buformin-mimicking poly(amido amine) for efficient and safe gene delivery

Biguanides (i.e. metformin, phenformin and buformin) are antidiabetic drugs with potential antitumor effects. Herein, a polycationic polymer, N,N'-bis(cystamine)acrylamide-buformin (CBA-Bu), containing multiple biodegradable disulphide bonds and buformin-mimicking side chains was synthesised. CBA-Bu was equipped with high efficiency and safety profile for gene delivery, meanwhile exhibiting potential antitumor efficacy. As a gene vector, CBA-Bu was able to condense plasmid DNA (pDNA) into nano-sized (<200 nm), positively-charged (>30 mV) uniform polyplexes that were well resistant to heparin and DNase I. Due to the reduction responsiveness of the disulphide bonds, CBA-Bu/pDNA polyplexes could release the loaded pDNA in the presence of dithiothreitol, and induce extremely low cytotoxicity in NIH/3T3 and U87 MG cells. The transfection results showed that CBA-Bu had a cellular uptake efficiency comparable to 25 kDa PEI, while a significantly higher gene expression level. Additionally, CBA-Bu had a lower IC50 value than its non-biguanide counterpart in two cancer cell lines. Furthermore, CBA-Bu could activate AMPK and inhibit mTOR pathways in U87 MG cells, a mechanism involved in the antitumor effect of biguanides. Taken together, CBA-Bu represented an advanced gene vector combining desirable gene delivery capability with potential antitumor activity, which was promising to achieve enhanced therapeutic efficacy in antitumor gene therapy.

Inhalable Gene Delivery System Using a Cationic RAGE-Antagonist Peptide for Gene Delivery to Inflammatory Lung Cells

Acute lung injury (ALI) is a severe lung inflammatory disease. In ALI, the receptor for advanced glycation end-products (RAGE) is overexpressed in lung epithelial cells and involved in inflammatory reactions. A previous report showed that a RAGE-antagonist peptide (RAP), from high-mobility group box-1, bound to RAGE and reduced inflammatory reactions. RAP has high levels of positive amino acids, which suggests that RAP may form a complex with plasmid DNA (pDNA) by charge interactions. Because the charge density of RAP is lower than polyethylenimine (25 kDa, PEI25k), it may be able to avoid capture by the negatively charged mucus layer more easily and deliver pDNA into RAGE-positive lung cells of ALI animals by RAGE-mediated endocytosis. To prove this hypothesis, RAP was evaluated as a delivery carrier of adiponectin plasmid (pAPN) in lipopolysaccharide (LPS)-induced ALI animal models. In vitro transfection assays showed that RAP had lower transfection efficiency than PEI25k in L2 lung epithelial cells. However, in vivo administration to ALI animal models by inhalation showed that RAP had higher gene delivery efficiency than PEI25k. Particularly, due to a higher expression of RAGE in lung cells of ALI animals, the gene delivery efficiency of RAP was higher in ALI animals than that in normal animals. Delivery of the pAPN/RAP complex had anti-inflammatory effects, reducing pro-inflammatory cytokines. Hematoxylin and eosin staining confirmed that pAPN/RAP decreased inflammation in ALI models. Therefore, the results suggest that RAP may be useful as a carrier of pDNA into the lungs for ALI gene therapy.