Long dsRNA-Mediated RNA Interference and Immunostimulation: A Targeted Delivery Approach Using Polyethyleneimine Based Nano-Carriers

Simultaneous silencing of juvenile hormone metabolism genes through RNAi interrupts metamorphosis in the cotton boll weevil

The cotton boll weevil (CBW) (Anthonomus grandis) is one of the major insect pests of cotton in Brazil. Currently, CBW control is mainly achieved by insecticide application, which is costly and insufficient to ensure effective crop protection. RNA interference (RNAi) has been used in gene function analysis and the development of insect control methods. However, some insect species respond poorly to RNAi, limiting the widespread application of this approach. Therefore, nanoparticles have been explored as an option to increase RNAi efficiency in recalcitrant insects. Herein, we investigated the potential of chitosan-tripolyphosphate (CS-TPP) and polyethylenimine (PEI) nanoparticles as a dsRNA carrier system to improve RNAi efficiency in the CBW. Different formulations of the nanoparticles with dsRNAs targeting genes associated with juvenile hormone metabolism, such as juvenile hormone diol kinase (JHDK), juvenile hormone epoxide hydrolase (JHEH), and methyl farnesoate hydrolase (MFE), were tested. The formulations were delivered to CBW larvae through injection (0.05-2 µg), and the expression of the target genes was evaluated using RT-qPCR. PEI nanoparticles increased targeted gene silencing compared with naked dsRNAs (up to 80%), whereas CS-TPP-dsRNA nanoparticles decreased gene silencing (0%-20%) or led to the same level of gene silencing as the naked dsRNAs (up to 50%). We next evaluated the effects of targeting a single gene or simultaneously targeting two genes via the injection of naked dsRNAs or dsRNAs complexed with PEI (500 ng) on CBW survival and phenotypes. Overall, the gene expression analysis showed that the treatments with PEI targeting either a single gene or multiple genes induced greater gene silencing than naked dsRNA (∼60%). In addition, the injection of dsJHEH/JHDK, either naked or complexed with PEI, significantly affected CBW survival (18% for PEI nanoparticles and 47% for naked dsRNA) and metamorphosis. Phenotypic alterations, such as uncompleted pupation or malformed pupae, suggested that JHEH and JHDK are involved in developmental regulation. Moreover, CBW larvae treated with dsJHEH/JHDK + PEI (1,000 ng/g) exhibited significantly lower survival rate (55%) than those that were fed the same combination of naked dsRNAs (30%). Our findings demonstrated that PEI nanoparticles can be used as an effective tool for evaluating the biological role of target genes in the CBW as they increase the RNAi response.

Advances in nanotechnology-based platforms for survivin-targeted drug discovery

INTRODUCTION

Due to its unique functional impact on multiple cancer cell circuits including proliferation, apoptosis, tumor dissemination, DNA damage repair and immune response, the inhibitor of apoptosis protein (IAP) survivin has gained high interest as a molecular target and a multitude of therapeutics were developed to interfere with survivin expression and functionality. First clinical evaluations of these therapeutics, however, were disappointing highlighting the need to develop advanced delivery systems of survivin-targeting molecules to increase stability, bioavailability as well as the selective guidance to tumor tissue.

AREAS COVERED

: This review focuses on advancements in nanocarriers to molecularly target survivin in human malignancies. A plethora of nanoparticle platforms, including liposomes, polymeric systems, dendrimers, inorganic nanocarriers, RNA/DNA nanotechnology and exosomes are discussed in the background of survivin-tailored RNA interference, small molecule inhibitors, dominant negative mutants or survivin vaccination or combined modality treatment with chemotherapeutic drugs and photo- dynamic/photothermal strategies.

EXPERT OPINION

Novel therapeutic approaches include the use of biocompatible nanoformulations carrying gene silencing or drug molecules to directly or indirectly target proteins, allow for a more precise and controlled delivery of survivin therapeutics. Moreover, surface modification of these nanocarriers may result in a tumor entity specific delivery. Therefore, nanomedicine exploiting survivin-tailored strategies in a multimodal background is considered the way forwaerd to enhance the development of future personalized medicine.

Utilization of rGO-PEI-supported AgNPs for sensitive recognition of deltamethrin in human plasma samples: A new platform for the biomedical analysis of pesticides in human biofluids

In this study, the rGO-PEI-AgNPs sensor was designed as a new effective platform to sensitive monitoring of deltamethrin in human plasma samples. For this purpose, reduced graphene oxide (rGO)-supported polyethylenimine (PEI) was used as a suitable substrate for dispersion of silver nanoparticles (AgNPs) as amplification and catalytic element. Therefore, a novel interface (rGO-PEI-AgNPs) was prepared by the fully electrochemical method on the surface of glassy carbon electrodes. The engineered nano-sensor showed a wide dynamic range of 10 nM to 1 mM and low limit of quantification (LLOQ) as 10 nM in human plasma sample, which revealed excellent analytical performance for the recognition of deltamethrin with high sensitivity and reproducibility through differential pulse voltammetry and square wave voltammetry techniques. The results confirm that rGO-PEI-AgNPs as a novel biocompatible interface can provide appropriate, reliable, affordable, rapid, and user-friendly diagnostic tools in the detection of deltamethrin in human real samples.

Molecular Mechanism of the Antiproliferative Activity of Short Immunostimulating dsRNA

Small double-stranded RNAs with certain sequence motifs are able to interact with pattern-recognition receptors and activate the innate immune system. Recently, we identified a set of short double-stranded 19-bp RNA molecules with 3-nucleotide 3′-overhangs that exhibited pronounced antiproliferative activity against cancer cells in vitro, and antitumor and antimetastatic activities in mouse models in vivo. The main objectives of this study were to identify the pattern recognition receptors that mediate the antiproliferative action of immunostimulating RNA (isRNA). Two cell lines, epidermoid carcinoma KB-3-1 cells and lung cancer A549 cells, were used in the study. These lines respond to the action of isRNA by a decrease in the growth rate, and in the case of A549 cells, also by a secretion of IL-6. Two sets of cell lines with selectively silenced genes encoding potential sensors and signal transducers of isRNA action were obtained on the basis of KB-3-1 and A549 cells. It was found that the selective silencing of PKR and RIG-I genes blocked the antiproliferative effect of isRNA, both in KB-3-1 and A549 cells, whereas the expression of MDA5 and IRF3 was not required for the antiproliferative action of isRNA. It was shown that, along with PKR and RIG-I genes, the expression of IRF3 also plays a role in isRNA mediated IL-6 synthesis in A549 cells. Thus, PKR and RIG-I sensors play a major role in the anti-proliferative signaling triggered by isRNA.

Cell-SELEX-Based Identification of a Human and Mouse Cross-Reactive Endothelial Cell-Internalizing Aptamer

Increased interest and insights gained by researchers on the roles of endothelial cells in the pathophysiology of cancer, inflammatory, and cardiovascular diseases have led to the design of pharmacological interventions aimed at the endothelium lining in the diseased sites. Toward this end, we used established brain microvascular endothelial cell lines mouse (bEND3), human (hCMEC/D3), and Toggle Cell-SELEX to identify a species cross-reactive, endothelial cell-internalizing aptamer R11-3. This 2'F-modified RNA aptamer is specific for endothelial cells as no internalization was seen with cells of nonendothelial origin. R11-3 was truncated in size, and its potential in endothelial targeted therapeutics was established using VEGFR2 targeting long interfering RNA (liRNA) aptamer chimera. Due to its specificity for both mouse and human endothelial cells, we believe that this aptamer not only fits for development of endothelial targeted drug development for human diseases but is also suitable for preclinical evaluation in mice.

Core-shell hybrid nanostructured delivery platforms for advanced RNAi therapeutics

AIM

Study was aimed at combining the advantages of nonclassical RNAi-triggering oligonucleotides with nanoparticle-based advanced delivery platforms for developing efficient therapeutic systems.

MATERIALS & METHODS

We utilized a core-shell hybrid nanostructured platform for effectively delivering nonclassical RNAi triggers, namely long double stranded interfering RNA and tripodal interfering RNA. Core-shell structure was prepared by stably anchoring thiol-modified cationic polymer on the surface of growing crystal gold (Au) seeds, and the resulting particles were further complexed with nonclassical RNAi candidates via electrostatic interactions.

RESULTS

Our studies clearly demonstrated that the unique combination of nonclassical RNAi structures with an advanced core-shell hybrid nanostructured platform is an effective module for advanced RNAi-based therapeutic development.

Intranasal drug delivery of small interfering RNA targeting Beclin1 encapsulated with polyethylenimine (PEI) in mouse brain to achieve HIV attenuation

We previously reported that activation of the host autophagic protein, Beclin1, by HIV-1 infection represents an essential mechanism in controlling HIV replication and viral-induced inflammatory responses in microglial cells. Existing antiretroviral therapeutic approaches have been limited in their ability to cross the blood-brain barrier effectively and recognize and selectively eliminate persistent HIV-infected brain reservoirs. In the present study and for the first time, the bio-distribution and efficacy of noninvasive intranasal delivery of small interfering RNA (siRNA) against the Beclin1 gene using the cationic linear polyethylenimines (PEI) as a gene carrier was investigated in adult mouse brain. Fluorescein isothiocyanate (FITC)-labeled control siRNA delivered intranasally was found in the cytoplasm of neurons and glial cells of the prefrontal cortex at 4 and 24 hours post-delivery, with no major adverse immune reaction encountered. Intranasal delivery of the siRNA targeting Beclin1 significantly depleted the target protein expression levels in brain tissues with no evidence of toxicity. Binding of siRNA to PEI-polymer was characterized and confirmed by Raman spectroscopy. These results indicate that the intranasal drug delivery allows for the direct delivery of the PEI-siRNA nano-complex to the central nervous system, which could potentially offer an efficient means of gene silencing-mediated therapy in the HIV-infected brain.

Polyethylenimine: a very useful ionic polymer in the design of immobilized enzyme biocatalysts

This review discusses the possible roles of polyethylenimine (PEI) in the design of improved immobilized biocatalysts from diverse perspectives.

Antitumor and Antimetastatic Effect of Small Immunostimulatory RNA against B16 Melanoma in Mice

Small interfering RNAs, depending on their structure, delivery system and sequence, can stimulate innate and adaptive immunity. The aim of this study was to investigate the antitumor and antimetastatic effects of immunostimulatory 19-bp dsRNA with 3'- trinucleotide overhangs (isRNA) on melanoma B16 in C57Bl/6 mice. Recently developed novel cationic liposomes 2X3-DOPE were used for the in vivo delivery of isRNA. Administration of isRNA/2X3-DOPE complexes significantly inhibits melanoma tumor growth and metastasis. Histopathological analysis of spleen cross sections showed hyperplasia of the lymphoid white pulp and formation of large germinal centers after isRNA/2X3-DOPE administration, indicating activation of the immune system. The treatment of melanoma-bearing mice with isRNA/2X3-DOPE decreases the destructive changes in the liver parenchyma. Thus, the developed isRNA displays pronounced immunostimulatory, antitumor and antimetastatic properties against melanoma B16 and may be considered a potential agent in the immunotherapy of melanoma.

Periodic-shRNA molecules are capable of gene silencing, cytotoxicity and innate immune activation in cancer cells

Large dsRNA molecules can cause potent cytotoxic and immunostimulatory effects through the activation of pattern recognition receptors; however, synthetic versions of these molecules are mostly limited to simple sequences like poly-I:C and poly-A:U. Here we show that large RNA molecules generated by rolling circle transcription fold into periodic-shRNA (p-shRNA) structures and cause potent cytotoxicity and gene silencing when delivered to cancer cells. We determined structural requirements for the dumbbell templates used to synthesize p-shRNA, and showed that these molecules likely adopt a co-transcriptionally folded structure. The cytotoxicity of p-shRNA was robustly observed across four different cancer cell lines using two different delivery systems. Despite having a considerably different folded structure than conventional dsRNA, the cytotoxicity of p-shRNA was either equal to or substantially greater than that of poly-I:C depending on the delivery vehicle. Furthermore, p-shRNA caused greater NF-κB activation in SKOV3 cells compared to poly-I:C, indicating that it is a powerful activator of innate immunity. The tuneable sequence and combined gene silencing, immunostimulatory and cytotoxic capacity of p-shRNA make it an attractive platform for cancer immunotherapy.

Systemic in vivo delivery of siRNA to tumours using combination of polyethyleneimine and transferrin–polyethyleneimine conjugates

Materials for delivery of oligonucleotides need to be simple to produce and formulate yet effectivein vivoto be considered for clinical applications.

Guanidine modified polyethyleneimine-g-polyethylene glycol nanocarriers for long interfering RNA (liRNA) based advanced anticancer therapy

Long interfering RNA mediated advanced anticancer therapy.

Bioapplications of hyperbranched polymers

The recent research progress in biological and biomedical applications of hyperbranched polymers has been summarized in this review.

Synthesis and therapeutic applications of biocompatible or biodegradable hyperbranched polymers

The recent progress in the synthesis, modifications and therapeutic applications of biocompatible or biodegradable hyperbranched polymers has been reviewed.

Efficient intracellular delivery and multiple-target gene silencing triggered by tripodal RNA based nanoparticles: a promising approach in liver-specific RNAi delivery

RNA interference (RNAi) triggering oligonucleotides in unconventional structural format can offer advantages over conventional small interfering RNA (siRNA), enhanced cellular delivery and improved target gene silencing. With this concept, we present a well-defined tripodal-interfering RNA (tiRNA) structure that can induce simultaneous silencing of multiple target genes with improved potency. The tiRNA structure, formed by the complementary association of three single-stranded RNA units, was optimized for improved gene silencing efficacy. When combined with cationic polymers such as linear polyethyleneimine (PEI), tiRNA assembled to form a stable nano-structured complex through electrostatic interactions and induced stronger RNAi response over conventional siRNA-PEI complex. In combination with a liver-targeting delivery system, tripodal nucleic acid structure demonstrated enhanced fluorescent accumulation in mouse liver compared to standard duplex nucleic acid format. Tripodal RNA structure complexed with galactose-modified PEI could generate effective RNAi-mediated gene silencing effect on experimental mice models. Our studies demonstrate that optimized tiRNA structural format with appropriate polymeric carriers have immense potential to become an RNAi-based platform suitable for multi-target gene silencing.