Targeted Systemic Delivery of a Therapeutic siRNA with a Multifunctional Carrier Controls Tumor Proliferation in Mice

Abstract

In this study, novel peptide-targeted delivery systems were developed for systemic and targeted delivery of therapeutic siRNA based on a multifunctional carrier, (1-aminoethyl)iminobis[N-(oleicylcysteinylhistinyl-1-aminoethyl)propionamide] (EHCO), which showed pH-sensitive amphiphilic cell membrane disruption. EHCO formed stable nanoparticles with siRNA. Targeted siRNA delivery systems were readily formed by surface modification of the nanoparticles. PEGylation of the siRNA/EHCO nanoparticles significantly reduced nonspecific cell uptake. The incorporation of a bombesin peptide or RGD peptide via a PEG spacer resulted in receptor-mediated cellular uptake and high gene silencing efficiency in U87 cells. Fluorescence confocal microscopic studies demonstrated that EHCO/siRNA nanoparticles and PEG modified EHCO/siRNA nanoparticles were able to facilitate endosomal escape of the siRNA delivery systems. Systemic administration of a therapeutic anti-HIF-1alpha siRNA with the peptide-targeted delivery systems resulted in significant tumor growth inhibition than a nontargeted delivery system or free siRNA via intravenous injection in nude mice bearing human glioma U87 xenografts. The results indicate a great promise of the multifunctional carrier EHCO for systemic and targeted delivery of therapeutic siRNA to treat human diseases with RNAi.

RNA interference targeting hypoxia-inducible factor 1α via a novel multifunctional surfactant attenuates glioma growth in an intracranial mouse model

“…These data correlate with what we found previously with other siRNA-EHCO complex-protecting moieties. 61 IHC analysis revealed that the levels of several transcriptional targets of HIF-1a were reduced significantly in the tumors of mice treated with siRNA knocking down HIF-1a. Figure 6 shows representative IHC evidence that HIF-1, GLUT-1, CA-IX, c-MET, and VEGF were all reduced significantly in tumors treated with HIF-1a-target- ing siRNAs compared with the controls.…”

“…Previously, we and others 18,61 showed that RNAi can effectively knock down HIF-1a and affect tumor growth in a mouse flank tumor model; however, there are some concerns about the accuracy of that model, given the fundamental differences between the brain and flank environments. 3 Other studies have used short hairpin RNA-expressing cells to knock down HIF1a constitutively before implantation into animals.…”

“…Over a 49-day period, the mice were given daily intratumoral injections of 25 pmol of siRNA complexed to EHCO, as described previously. 60,61 The amount of siRNA to be injected was based on cell culture and previous tumor flank results. 18 Each mouse was anesthetized with isoflurane (2%, 1 L/minute oxygen), and the scalp area was wiped with ethanol and RNase ZAP (Ambion).…”

“…Recently, a novel class of multifunctional surfactants with pH-sensitive amphiphilicity for efficient siRNA delivery was designed and developed. 60,61 One of these surfactants, 1-(aminoethyl) iminobis[N-(oleicylcysteinylhistinyl-1-aminoethyl)propionamide] (EHCO), was used in the present study. A distinct advantage of this carrier is its pH-sensitive amphiphilicity and amphiphilic cell-membrane disruption at an endosomal-lysosomal pH, which can facilitate the specific endosomal-lysosomal release of an siRNA into the cytoplasm.…”

Intracellular siRNA delivery with novel spermine based surfactants

“…These functions enable the carriers to facilitate endosomal escape of the nanoparticles and to release nucleic acids into cytosol via reduction of the disulfide bonds in the nanoparticles by cytosolic glutathione. The multifunctional carriers have demonstrated high intra-cellular and in vivo siRNA delivery efficiency, resulting in high intracellular gene silencing efficiency and therapeutic efficacy in a mouse tumor model [10,11,17,18].…”