In vivo delivery of antisense MORF oligomer by MORF/carrier streptavidin nanoparticles

Polymer nanoparticle-mediated delivery of microRNA inhibition and alternative splicing

The crux of current RNA-based therapeutics relies on association of synthetic nucleic acids with cellular RNA targets. Antisense oligonucleotide binding to mature microRNA and splicing junctions on pre-mRNA represent methods of gene therapy that respectively inhibit microRNA-mediated gene regulation and induce alternative splicing. We have developed biodegradable polymer nanoparticles, which are coated with cell-penetrating peptides, that can effectively deliver chemically modified oligonucleotide analogues to achieve these forms of gene regulation. We found that this nanoparticle system could block the activity of the oncogenic microRNA, miR-155, as well as modulate splicing to attenuate the expression of the proto-oncogene, Mcl-1. Regulation of these genes in human cancer cells reduced cell viability and produced pro-apoptotic effects. These findings establish polymer nanoparticles as delivery vectors for nonconventional forms of gene therapy activated by cellular delivery of RNA-targeted molecules, which have strong therapeutic implications.

Radiolabeled nano-peptides show specificity for an animal model of human PC3 prostate cancer cells

OBJECTIVES

Cancer has been investigated using various pre-targeting techniques or models focusing on radiobombesin analogues; however, both are not offered together. In this study, nano-bombesin labeling by a pre-targeting system was undertaken to develop an alternative approach for prostate tumor treatment.

METHODS

A two-step pre-targeting system utilizing a combination of streptavidin (SA), biotinylated morpholino (B-MORF), biotinylated BBN (B-BBN) with two different spacers (b-Ala and PEG), and a radiolabeled cMORF was evaluated in vitro and in vivo.

RESULTS

Final conjugation conditions consisted of a 1:1:2 ratio of SA:B-MORF:B-BBN, followed by addition of 99mTc-cMORF to compensate for free MORF. In vitro binding experiments with prostate cancer cells (PC-3) revealed that total binding was time-dependent for the Ala spacer but not for the PEG spacer. The highest accumulation (5.06 ± 1.98 %) was achieved with 1 hour of incubation, decreasing as time progressed. Specific binding fell to 1.05 ± 0.35 %. The pre-targeting biodistribution in healthy Swiss mice was measured at different time points, with the best responses observed for 7-h and 15-h incubations. The effector, 99mTc-MAG3-cMORF, was administered 2 h later. Strong kidney excretion was always documented. The greatest tumor uptake was 2.58 ± 0.59 %ID/g at 7 h for B-bAla-BBN, with a region of interest (ROI) value of 3.9 % during imaging. The tumor/blood ratio was low due to the slow blood clearance; however, the tumor/muscle ratio was 5.95.

CONCLUSIONS

The pre-targeting approach with a peptide was a viable concept. Further evaluation with modified sequences of MORF, including less cytosine, and additional test intervals could be worthwhile.

Potential therapeutic applications of antisense morpholino oligonucleotides in modulation of splicing in primary immunodeficiency diseases

Highly complementary antisense morpholino oligonucleotides (AMOs) can bind to pre-mRNA and modulate splicing site selection. This offers a powerful tool to regulate the splicing process, such as correcting subtypes of splicing mutations and nonsense mutations and reprogramming alternative splicing processes. Therefore, AMO-mediated splicing modulation represents an attractive therapeutic strategy for genetic disorders. Primary immunodeficiency diseases (PIDs) are a heterogeneous group of genetic disorders that result from mutations in genes involved in development and maintenance of the immune system. Many of these mutations are splicing mutations and nonsense mutations that can be manipulated by AMOs. This review discusses AMO-mediated splicing modulation approaches and their potential applications in treating PIDs.