RNA interference and potential therapeutic applications of short interfering RNAs

Precision arrows: Navigating breast cancer with nanotechnology siRNA

Nanotechnology-based drug delivery systems, including siRNA, present an innovative approach to treating breast cancer, which disproportionately affects women. These systems enable personalized and targeted therapies, adept at managing drug resistance and minimizing off-target effects. This review delves into the current landscape of nanotechnology-derived siRNA transport systems for breast cancer treatment, discussing their mechanisms of action, preclinical and clinical research, therapeutic applications, challenges, and future prospects. Emphasis is placed on the importance of targeted delivery and precise gene silencing in improving therapeutic efficacy and patient outcomes. The review addresses specific hurdles such as specificity, biodistribution, immunological reactions, and regulatory approval, offering potential solutions and avenues for future research. SiRNA drug delivery systems hold promise in revolutionizing cancer care and improving patient outcomes, but realizing their full potential necessitates ongoing research, innovation, and collaboration. Understanding the intricacies of siRNA delivery mechanisms is pivotal for designing effective cancer treatments, overcoming challenges, and advancing siRNA-based therapies for various diseases, including cancer. The article provides a comprehensive review of the methods involved in siRNA transport for therapeutic applications, particularly in cancer treatment, elucidating the complex journey of siRNA molecules from extracellular space to intracellular targets. Key mechanisms such as endocytosis, receptor-mediated uptake, and membrane fusion are explored, alongside innovative delivery vehicles and technologies that enhance siRNA delivery efficiency. Moreover, the article discusses challenges and opportunities in the field, including issues related to specificity, biodistribution, immune response, and clinical translation. By comprehending the mechanisms of siRNA delivery, researchers can design and develop more effective siRNA-based therapies for various diseases, including cancer.

Nontoxic, Biodegradable Hyperbranched Poly(β-amino ester)s for Efficient siRNA Delivery and Gene Silencing

RNA interference (RNAi)-mediated gene silencing is a promising therapeutic approach to treat various diseases, but safe and efficient delivery remains a major challenge to its clinical application. Non-viral gene vectors, such as poly(β-amino esters) (pBAEs), have emerged as a potential candidate due to their biodegradability, low toxicity profile, ease of synthesis, and high gene transfection efficiency for both DNA and siRNA delivery. However, achieving significant gene silencing using pBAEs often requires a large amount of polymer carrier (with polymer/siRNA weight ratio >100) or high siRNA dose (>100 nM), which might potentially exacerbate toxicity concerns during delivery. To overcome these barriers, we designed and optimized a series of hyperbranched pBAEs capable of efficiently condensing siRNA and achieving excellent silencing efficiency at a lower polymer/siRNA weight ratio (w/w) and siRNA dose. Through modulation of monomer combinations and branching density, we identified the top-performing hyperbranched pBAEs, named as h(A2B3)-1, which possess good siRNA condensation ability, low cytotoxicity, and high cellular uptake efficiency. Compared with Lipofectamine 2000, h(A2B3)-1 achieved lower cytotoxicity and higher siRNA silencing efficiency in HeLa cells at a polymer/siRNA weight ratio of 30 and 30 nM siRNA dose. Notably, h(A2B3)-1 enhanced the gene uptake in primary neural cells and effectively silenced the target gene in hard-to-transfect primary cortical neurons and oligodendrocyte progenitor cells, with gene knockdown efficiencies of 34.8 and 53.4% respectively. By incorporating a bioreducible disulfide compartment into the polymer backbone, the cytocompatibility of the h(A2B3)-1 was greatly enhanced while maintaining their good transfection efficiency. Together, the low cytotoxicity and high siRNA transfection efficiency of hyperbranched h(A2B3)-1 in this study demonstrated their great potential as a non-viral gene vector for efficient siRNA delivery and RNAi-mediated gene silencing. This provides valuable insight into the future development of safe and efficient non-viral siRNA delivery systems as well as their translation into clinical applications.

RNA Vaccines: Yeast as a Novel Antigen Vehicle

In the last decades, technological advances for RNA manipulation enabled and expanded its application in vaccine development. This approach comprises synthetic single-stranded mRNA molecules that direct the translation of the antigen responsible for activating the desired immune response. The success of RNA vaccines depends on the delivery vehicle. Among the systems, yeasts emerge as a new approach, already employed to deliver protein antigens, with efficacy demonstrated through preclinical and clinical trials. β-glucans and mannans in their walls are responsible for the adjuvant property of this system. Yeast β-glucan capsules, microparticles, and nanoparticles can modulate immune responses and have a high capacity to carry nucleic acids, with bioavailability upon oral immunization and targeting to receptors present in antigen-presenting cells (APCs). In addition, yeasts are suitable vehicles for the protection and specific delivery of therapeutic vaccines based on RNAi. Compared to protein antigens, the use of yeast for DNA or RNA vaccine delivery is less established and has fewer studies, most of them in the preclinical phase. Here, we present an overview of the attributes of yeast or its derivatives for the delivery of RNA-based vaccines, discussing the current challenges and prospects of this promising strategy.

Molecular Mechanisms of Anti-Estrogen Therapy Resistance and Novel Targeted Therapies

Breast cancer (BC) is the most commonly diagnosed cancer in women, constituting one-third of all cancers in women, and it is the second leading cause of cancer-related deaths in the United States. Anti-estrogen therapies, such as selective estrogen receptor modulators, significantly improve survival in estrogen receptor-positive (ER+) BC patients, which represents about 70% of cases. However, about 60% of patients inevitably experience intrinsic or acquired resistance to anti-estrogen therapies, representing a major clinical problem that leads to relapse, metastasis, and patient deaths. The resistance mechanisms involve mutations of the direct targets of anti-estrogen therapies, compensatory survival pathways, as well as alterations in the expression of non-coding RNAs (e.g., microRNA) that regulate the activity of survival and signaling pathways. Although cyclin-dependent kinase 4/6 and phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) inhibitors have significantly improved survival, the efficacy of these therapies alone and in combination with anti-estrogen therapy for advanced ER+ BC, are not curative in advanced and metastatic disease. Therefore, understanding the molecular mechanisms causing treatment resistance is critical for developing highly effective therapies and improving patient survival. This review focuses on the key mechanisms that contribute to anti-estrogen therapy resistance and potential new treatment strategies alone and in combination with anti-estrogen drugs to improve the survival of BC patients.

Cationic Liposomes as Vectors for Nucleic Acid and Hydrophobic Drug Therapeutics

Cationic liposomes (CLs) are effective carriers of a variety of therapeutics. Their applications as vectors of nucleic acids (NAs), from long DNA and mRNA to short interfering RNA (siRNA), have been pursued for decades to realize the promise of gene therapy, with approvals of the siRNA therapeutic patisiran and two mRNA vaccines against COVID-19 as recent milestones. The long-term goal of developing optimized CL-based NA carriers for a broad range of medical applications requires a comprehensive understanding of the structure of these vectors and their interactions with cell membranes and components that lead to the release and activity of the NAs within the cell. Structure-activity relationships of lipids for CL-based NA and drug delivery must take into account that these lipids act not individually but as components of an assembly of many molecules. This review summarizes our current understanding of how the choice of the constituting lipids governs the structure of their CL-NA self-assemblies, which constitute distinct liquid crystalline phases, and the relation of these structures to their efficacy for delivery. In addition, we review progress toward CL-NA nanoparticles for targeted NA delivery in vivo and close with an outlook on CL-based carriers of hydrophobic drugs, which may eventually lead to combination therapies with NAs and drugs for cancer and other diseases.

RNA Interference and Nanotechnology: A Promising Alliance for Next Generation Cancer Therapeutics

Cancer is a significant health hazard of the 21st century, and GLOBOCAN predicts increasing cancer incidence in the coming decades. Though several conventional treatment modalities exist, most of them end up causing off-target and debilitating effects, and drug resistance acquisition. Advances in our understanding of tumor molecular biology offer alternative strategies for precise, robust, and potentially less toxic treatment paradigms for circumventing the disease at the cellular and molecular level. Several deregulated molecules associated with tumorigenesis have been developed as targets in RNA interference (RNAi) based cancer therapeutics. RNAi, a post-transcriptional gene regulation mechanism, has significantly gained attention because of its precise multi-targeted gene silencing. Although the RNAi approach is favorable, the direct administration of small oligonucleotides has not been fruitful because of their inherent lower half-lives and instability in the biological systems. Moreover, the lack of an appropriate delivery system to the primary site of the tumor that helps determine the potency of the drug and its reach, has limited the effective medical utilization of these bio-drugs. Nanotechnology, with its unique characteristics of enhanced permeation and better tumor-targeting efficiency, offers promising solutions owing to the various possibilities and amenability for modifications of the nanoparticles to augment cancer therapeutics. Nanoparticles could be made multimodal, by designing and synthesizing multiple desired functionalities, often resulting in unique and potentially applicable biological structures. A small number of Phase I clinical trials with systemically administered siRNA molecules conjugated with nanoparticles have been completed and the results are promising, indicating that, these new combinatorial therapies can successfully and safely be used to inhibit target genes in cancer patients to alleviate some of the disease burden. In this review, we highlight different types of nano-based delivery strategies for engineering Nano-RNAi-based bio drugs. Furthermore, we have highlighted the insights gained from current research that are entering the preclinical evaluation and information about initial clinical developments, shaping the future for next generation cancer therapeutics.

Synthesis of Double Interfering Biodegradable Nano-MgO Micelle Composites and Their Effect on Parkinson's Disease

Although gene therapy targeting the α-synuclein gene (SNCA) has achieved outstanding results in the treatment of Parkinson's disease (PD), the lack of a suitable gene delivery system and inadequate therapeutic effects remains a tremendous obstacle for RNAi therapy. Here, a degradable nano-MgO micelle composite (MgO(pDNA)-INS-Plu-mRNA-NGF) with double interference (mediated by RNAi and α-synuclein (α-syn)-targeted mRNA) was constructed. Binding mRNA treatment significantly increased the inhibitory effect compared to the reduction of α-syn expression by RNAi alone. Moreover, the cell experiments demonstrated that the viability of the PD cell model can be significantly improved by nano-MgO micelle composite treatment. More importantly, the composite has the ability to penetrate the blood brain barrier and deliver genes and mRNA to neurons through endocytosis mediated by the nerve growth factor and its receptors, thus significantly downregulating the expression of α-syn in the PD mice model without causing damage to other major organs. Overall, this work provides a novel insight into the design of biomaterials for gene therapy for PD.

Sixteen Different Types of Lipid-Conjugated siRNAs Containing Saturated and Unsaturated Fatty Acids and Exhibiting Enhanced RNAi Potency

SiRNAs are strong gene-silencing agents that function in a target sequence-specific manner. Although siRNAs might one day be used in therapy for intractable diseases such as cancers, a number of problems with siRNAs must first be overcome. In this study, we developed 16 different types of lipid-conjugated siRNAs (lipid-siRNAs) that could effectively inhibit the expression of target genes. We determined the hybridization properties, cellular uptake efficacies, and RNAi potencies of the resulting lipid-siRNAs. The lipid-siRNAs exhibited a mild interaction with Lipofectamine RNAiMAX (LFRNAi) as a transfection reagent, and a high membrane permeability was observed in all lipid-siRNAs-LFRNAi complexes; the conjugate siRNAs composed of 16-18 carbon chains as fatty acids showed an especially good cellular uptake efficacy. The in vitro RNAi effect of lipid-siRNAs targeted to a β-catenin gene exhibited a strong RNAi potency compared with those of unmodified siRNAs. In particular, the conjugate siRNAs composed of 16-18 carbon chains as fatty acids showed excellent RNAi potencies with prolonged effectivities. Interestingly, the RNAi potencies of conjugate siRNAs containing 18 carbon chains with a trans-form (elaidic acid and trans-vaccenic acid) were inferior to those of the carbon chains with a cis-form (oleic acid and cis-vaccenic acid). These lipid-siRNAs can solve the many problems hindering the clinical application of siRNAs.

Naturally-occurring bacterial cellulose-hyperbranched cationic polysaccharide derivative/MMP-9 siRNA composite dressing for wound healing enhancement in diabetic rats

The anomalous high expression of matrix metalloproteinase 9 (MMP-9) is one important factor that impedes diabetic wound healing. Therefore, inhibition of MMP-9 expression in a diabetic wound could be a feasible method to promote wound healing. In this study, we studied the possibility of self-therapy using wound dressings that contain bacterial cellulose-hyperbranched cationic polysaccharide (BC-HCP) derivatives that encapsulate siRNA (BC-HCP/siMMP-9) and have controlled release properties. Herein, we used four HCPs (Gly-DMAPA, Gly-D4, Amyp-DMAPA, Amyp-D4) as gene carriers. Our results showed that all HCP derivatives were minimally toxic to cells in vitro, while the cationic properties of HCP could be used as a complexation agent for MMP-9 siRNA (siMMP-9). Upon exposure to bacterial cellulose (BC), the BC slowly released HCP/siMMP-9. The released siMMP-9 effectively reduced the gene expression and protein levels of MMP-9 in a human immortalized epithelial cell line (HaCAT) and in diabetic rat wounds. Inhibition of MMP-9 in the wounds of diabetic rats resulted in a significant enhancement of wound healing, suggesting that the BC-HCP/siMMP-9 composite dressing could be used as a safe and effective dressing to promote wound healing in diabetic rats. STATEMENT OF SIGNIFICANCE: In this work, we evaluated the possibility of using bacterial cellulose-hyperbranched cationic polysaccharide derivatives (BC-HCP) as a self-therapeutic wound dressing with siRNA encapsulated and controlled release properties. Our results showed that the BC-HCP/siMMP-9 composite dressing slowly released HCP/siMMP-9. The released siMMP-9 effectively reduced the gene expression and protein level of MMP-9 in human immortalized epithelial cell line and in the wound of diabetic rats. The BC-HCP/siMMP-9 composite dressing promoted diabetic wound healing by the unique nanostructure of BC and by releasing siMMP-9 for specific MMP-9 inhibition. Therefore, it could be used as a safe and effective dressing to promote wound healing in diabetic rats. This is the first evidence on the study of using BC as a dressing composite by encapsulating HCP/siRNA complexes for efficient RNAi gene silencing for better wound healing in diabetic rats.

Elimination of HER3-expressing breast cancer cells using aptamer-siRNA chimeras

Breast cancer is the most common cancer in women worldwide. Despite recent developments in breast cancer detection and treatment, 1.38 million women each year are still affected. Breast cancer heterogeneity at the population and single-cell level, complexity and developing different metastases are setting several challenges to develop efficient breast cancer therapies. RNA interference (RNAi) represents an opportunity to silence gene expression and inhibit specific pathways in cancer cells. In order to reap the full advantages of RNAi-based therapy, different pathways that sustain cancer cells growth have been targeted using specific siRNAs. The present study investigated the ability of a set of cytotoxic siRNAs to inhibit growth of breast cancer cells. These siRNAs are targeting eukaryotic elongation factor 2 (EEF2), polo-like kinase 1 (PLK1), G protein-coupled receptor kinase 4 (GRK4) and sphingosine kinase interacting protein (SKIP5). To facilitate their targeted delivery, the human epidermal growth factor receptor-3 (HER3)-specific aptamer A30 was used. The in vitro results described in this work indicate that combining the highly specific HER3 aptamer with cytotoxic siRNAs targeting (EEF2, PLK1, GRK4 and SKIP5) can inhibit its activity and ultimately suppress proliferation of HER3 positive breast cancer cells.

Thymosin Beta 4 Is Involved in the Development of Electroacupuncture Tolerance

Background: Electroacupuncture (EA) tolerance, a negative therapeutic effect, is a gradual decline in antinociception because of its repeated or prolonged use. This study aims to explore the role of thymosin beta 4 (Tβ4), having neuro-protection properties, in EA tolerance (EAT).

Methods: Rats were treated with EA once daily for eight consecutive days to establish EAT, effect of Tβ4 on the development of EAT was determined through microinjection of Tβ4 antibody and siRNA into the cerebroventricle. The mRNA and protein expression profiles of Tβ4, opioid peptides (enkephalin, dynorphin and endorphin), and anti-opioid peptides (cholecystokinin octapeptide, CCK-8 and orphanin FQ, OFQ), and mu opioid receptor (MOR) and CCK B receptor (CCKBR) in the brain areas (hypothalamus, thalamus, cortex, midbrain and medulla) were characterized after Tβ4 siRNA was administered.

Results: Tβ4 levels were increased at day 1, 4, and 8 and negatively correlated with the changes of tail flick latency in all areas. Tβ4 antibody and siRNA postponed EAT. Tβ4 siRNA caused decreased Tβ4 levels in all areas, which resulted in increased enkephalin, dynorphin, endorphin and MOR levels in most measured areas during repeated EA, but unchanged OFQ, CCK-8, and CCKBR levels in most measured areas. Tβ4 levels were negatively correlated with enkephalin, dynorphin, endorphin, or MOR levels in all areas except medulla, while positively correlated with OFQ and CCK-8 levels in some areas.

Conclusion: These results confirmed Tβ4 facilitates EAT probably through negatively changing endogenous opioid peptides and their receptors and positively influencing anti-opioid peptides in the central nervous system.

DNA-surfactant complexes: self-assembly properties and applications

Over the last few years, DNA-surfactant complexes have gained traction as unique and powerful materials for potential applications ranging from optoelectronics to biomedicine because they self-assemble with outstanding flexibility spanning packing modes from ordered lamellar, hexagonal and cubic structures to disordered isotropic phases. These materials consist of a DNA backbone from which the surfactants protrude as non-covalently bound side chains. Their formation is electrostatically driven and they form bulk films, lyotropic as well as thermotropic liquid crystals and hydrogels. This structural versatility and their easy-to-tune properties render them ideal candidates for assembly in bulk films, for example granting directional conductivity along the DNA backbone, for dye dispersion minimizing fluorescence quenching allowing applications in lasing and nonlinear optics or as electron blocking and hole transporting layers, such as in LEDs or photovoltaic cells, owing to their extraordinary dielectric properties. However, they do not only act as host materials but also function as a chromophore itself. They can be employed within electrochromic DNA-surfactant liquid crystal displays exhibiting remarkable absorptivity in the visible range whose volatility can be controlled by the external temperature. Concomitantly, applications in the biological field based on DNA-surfactant bulk films, liquid crystals and hydrogels are rendered possible by their excellent gene and drug delivery capabilities. Beyond the mere exploitation of their material properties, DNA-surfactant complexes proved outstandingly useful for synthetic chemistry purposes when employed as scaffolds for DNA-templated reactions, nucleic acid modifications or polymerizations. These promising examples are by far not exhaustive but foreshadow their potential applications in yet unexplored fields. Here, we will give an insight into the peculiarities and perspectives of each material and are confident to inspire future developments and applications employing this emerging substance class.

RNAi technique, how far is it from pediatrics?

The new technology of ribonucleic acid interference (RNAi) or small/short interfering RNA (siRNA) can be used to reduce expression of genes in a sequence specific manner, and thereby can treat various diseases caused by expression or overexpression of genes. Phase 1 and phase 2 clinical studies on application of this technology to treat diseases have demonstrated efficacy and safety of this approach in a few specialties/subspecialties. However, no clinical trials have been reported in the fields of pediatrics. This article aimed to describe very briefly what the RNAi technique is, examples of demonstration of the efficacy and safety of RNAi techniques in a few different fields of clinical medicine, and to encourage pediatricians and pediatric researchers to actively participate in studies on this new therapeutic approach for treatment of various pediatric diseases.

Targeted silencing of SOX2 by an artificial transcription factor showed antitumor effect in lung and esophageal squamous cell carcinoma

SOX2 is a transcription factor essential for early mammalian development and for the maintenance of stem cells. Recently, SOX2 was identified as a lineage specific oncogene, recurrently amplified and activated in lung and esophageal squamous cell carcinoma (SCC). In this study, we have developed a zinc finger-based artificial transcription factor (ATF) to selectively suppress SOX2 expression in cancer cells and termed the system ATF/SOX2. We engineered the ATF using six zinc finger arrays designed to target a 19 bp site in the SOX2 distal promoter and a KOX transcriptional repressor domain. A recombinant adenoviral vector Ad-ATF/SOX2 that expresses ATF/SOX2 suppressed SOX2 at the mRNA and protein levels in lung and esophageal SCC cells expressing SOX2. In these kinds of cells, Ad-ATF/SOX2 decreased cell proliferation and colony formation more effectively than the recombinant adenoviral vector Ad-shSOX2, which expresses SOX2 short hairpin RNA (shSOX2). Ad-ATF/SOX2 induced the cell cycle inhibitor CDKN1A more strongly than Ad-shSOX2. Importantly, the ATF did not suppress the cell viability of normal human cells. Moreover, Ad-ATF/SOX2 effectively inhibited tumor growth in a lung SCC xenograft mouse model. These results indicate that ATF/SOX2 would lead to the development of an effective molecular-targeted therapy for lung and esophageal SCC.

Therapeutic potentials of short interfering RNAs

Short interfering RNA (siRNA) is one of the members of the family of RNA interference (RNAi). Coupled with the RNA-induced silencing complex (RISC), siRNA is able to trigger the cleavage of target RNAs which serve as a defensive system against pathogens. Meanwhile, siRNA in gene silencing opens a new avenue for the treatment of various diseases. SiRNA can effectively inhibit viral infection and replication and suppress tumorigenesis and various inflammation-associated diseases and cardiovascular diseases by inactivation of viral genes and downregulation of oncogene expression. Recently, endogenous siRNAs (endo-siRNAs) were discovered in the reproductive cells of animals which may be associated with regulation of cell division. Structural modification of siRNA enhances the delivery, specificity and efficacy and bioavailability to the target cells. There are at least five categories of siRNA delivery systems including viral vectors, lipid-based nanoparticles, peptide-based nanoparticles, polymer-based nanoparticles and inorganic small molecules like metal ions, silica and carbon. Sufficient preclinical and clinical studies supported that siRNA may be a potential medicine for targeted therapy of various diseases in the near future.

Effect of NIMA-related kinase 2B on the sensitivity of breast cancer to paclitaxel in vitro and vivo

NIMA-related kinase 2B has been known to be an important centrosome regulatory factor. The aim of this study was to investigate the effect of NIMA-related kinase 2B on the sensitivity of breast cancer to paclitaxel. We detected the expression of NIMA-related kinase 2B messenger RNA in MCF-10 cells, including MCF-10A, MCF-10AT, MCF-10DCIS.com , and MCF-10CA1a. The influence of NIMA-related kinase 2B in nude mouse was also detected. The association between NIMA-related kinase 2B and clinicopathological factors was explored in invasive ductal carcinoma tissues. NIMA-related kinase 2B was lowly expressed in the precancerous cells, MCF-10A and MCF-10AT, and it was highly expressed in carcinomatous cells, MCF-10DCIS.com and MCF-10CA1a. The upregulation of NIMA-related kinase 2B can introduce the growth of MCF-10AT cells, knockdown of NIMA-related kinase 2B could remarkably inhibit cell proliferation in MCF-10DCIS.com and MCF-10 CA1a cells. Comparing the volume of the xenografts in nude mouse, we found that the tumors treated by NIMA-related kinase 2B small interfering RNA associated with paclitaxel were the smallest among all the groups. Expression of NIMA-related kinase 2B messenger RNA was associated with higher histological grades, positive lymph node, and high Ki67 index (>20%). The partial response rates were 75.0% in NIMA-related kinase 2B negative (NIMA-related kinase 2B-) patients and 15.8% in NIMA-related kinase 2B++ patients. The progressive disease rates were 10.0% in NIMA-related kinase 2B- patients and 52.6% in NIMA-related kinase 2B++ patients ( p = 0.002). Our findings suggested that NIMA-related kinase 2B could play a role in the development and progression of breast cancer. Combination treatment using NIMA-related kinase 2B small interfering RNA and paclitaxel might be a novel potential therapy method for breast cancer.

Proof-of-concept study: profile of circulating microRNAs in Bovine serum harvested during acute and persistent FMDV infection

Background

Changes in the levels of circulating microRNAs (miRNAs) in the serum of humans and animals have been detected as a result of infection with a variety of viruses. However, to date, such a miRNA profiling study has not been conducted for foot-and-mouth disease virus (FMDV) infection.

Methods

The relative abundance of 169 miRNAs was measured in bovine serum collected at three different phases of FMDV infection in a proof-of-concept study using miRNA PCR array plates.

Results

Alterations in specific miRNA levels were detected in serum during acute, persistent, and convalescent phases of FMDV infection. Subclinical FMDV persistence produced a circulating miRNA profile distinct from cattle that had cleared infection. bta-miR-17-5p was highest expressed during acute infection, whereas bta-miR-31 was the highest during FMDV persistence. Interestingly, miR-1281was significantly down-regulated during both acute and persistent infection. Cattle that cleared infection resembled the baseline profile, adding support to applying serum miRNA profiling for identification of sub-clinically infected FMDV carriers. Significantly regulated miRNAs during acute or persistent infection were associated with cellular proliferation, apoptosis, modulation of the immune response, and lipid metabolism.

Conclusions

These findings suggest a role for non-coding regulatory RNAs in FMDV infection of cattle. Future studies will delineate the individual contributions of the reported miRNAs to FMDV replication, determine if this miRNA signature is applicable across all FMDV serotypes, and may facilitate development of novel diagnostic applications.

Electronic supplementary material

The online version of this article (doi:10.1186/s12985-017-0743-3) contains supplementary material, which is available to authorized users.

Host microRNA-203a Is antagonistic to the progression of foot-and-mouth disease virus infection

Sam68 was previously shown to be a critical host factor for foot-and-mouth disease virus (FMDV) replication. MicroRNA (miR) miR-203a is reportedly a negative regulator of Sam68 expression both in vitro and in vivo. Here, transfection of miR-203a-3p and miR-203a-5p mimics separately and in combination in a porcine cell line followed by FMDV infection resulted in diminished viral protein synthesis and a 4 and 6log reduction in virus titers relative to negative controls, respectively. Unexpectedly, Sam68 expression was increased by miR-203a-5p transfection, but not miR-203a-3p. miR-203a-5p also down-regulated Survivin expression, which was predicted to play a role in FMDV infection. Moreover, miR-203a-5p but not miR-203a-3p affected a reduction in FMDV viral RNA. These effects were not replicated with a related Picornavirus, suggesting FMDV specificity. Importantly, miR-203a-3p and miR-203a-5p impaired FMDV infection across multiple FMDV serotypes. We concluded that miR-203a-3p and miR-203a-5p represent attractive potential naturally occurring bio-therapeutics against FMDV.

Inhibition of cell proliferation and migration after HTRA1 knockdown in retinal pigment epithelial cells

PURPOSE

The purpose of this study was to investigate the role of HtrA serine peptidase 1 (HTRA1) in the proliferation and migration of cells of the human retinal pigment epithelial cell line ARPE-19, and the possible mechanisms involved.

METHODS

ARPE-19 cells were transduced by a recombinant lentiviral vector carrying HTRA1-shRNA to knockdown HTRA1 expression. Subsequent HTRA1 gene and HTRA1 protein levels in these cells and control cells were detected by quantitative real-time PCR and Western blot, respectively. Changes in cell proliferation and migration associated with the inhibition of HTRA1 expression were assessed, as well as changes in the mRNA levels of transforming growth factor beta 1 (TGFB1), bone morphogenetic protein 4 (BMP4), and bone morphogenetic protein 2 (BMP2).

RESULTS

The recombinant lentivirus carrying HTRA1-shRNA was successfully generated, as evidenced by reduced levels of HTRA1 mRNA and HTRA1 protein in ARPE-19 cells. The knockdown of HTRA1 in ARPE-19 cells was associated with reduced cellular proliferation and migration, and increased mRNA levels of TGF-β1, BMP4, and BMP2.

CONCLUSIONS

Silence of the HTRA1 gene was associated with significantly higher levels of TGF-β1, BMP4, and BMP2 mRNA and reduction in the proliferation and migration of ARPE-19 cells.

Co-delivery of siRNA and paclitaxel into cancer cells by hyaluronic acid modified redox-sensitive disulfide-crosslinked PLGA–PEI nanoparticles

Schematic diagram showing the structure of the co-delivery nano-complex and the process of entering tumor cells.

Targeted silencing of inhibitors of apoptosis proteins with siRNAs: a potential anti-cancer strategy for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignancies, with a very poor prognosis. Despite significant improvements in diagnosis and treatment in recent years, the long-term therapeutic efficacy is poor, partially due to tumor metastasis, recurrence, and resistance to chemo- or radio-therapy. Recently, it was found that a major feature of tumors is a combination of unrestrained cell proliferation and impaired apoptosis. There are now 8 recognized members of the IAP-family: NAIP, c-IAP1, c-IAP2, XIAP, Survivin, Bruce, Livin and ILP-2. These proteins all contribute to inhibition of apoptosis, and provide new potential avenues of cancer treatment. As a powerful tool to suppress gene expression in mammalian cells, RNAi species for inhibiting IAP genes can be directed against cancers. This review will provide a brief introduction to recent developments of the application IAP-siRNA in tumor studies, with the aim of inspiring future treatment of HCC.

Inhibition of monocyte adhesion to brain-derived endothelial cells by dual functional RNA chimeras

Because adhesion of leukocytes to endothelial cells is the first step of vascular-neuronal inflammation, inhibition of adhesion and recruitment of leukocytes to vascular endothelial cells will have a beneficial effect on neuroinflammatory diseases. In this study, we used the pRNA of bacteriophage phi29 DNA packaging motor to construct a novel RNA nanoparticle for specific targeting to transferrin receptor (TfR) on the murine brain-derived endothelial cells (bEND5) to deliver ICAM-1 siRNA. This RNA nanoparticle (FRS-NPs) contained a FB4 aptamer targeting to TfR and a siRNA moiety for silencing the intercellular adhesion molecule-1 (ICAM-1). Our data indicated that this RNA nanoparticle was delivered into murine brain-derived endothelial cells. Furthermore, the siRNA was released from the FRS-NPs in the cells and knocked down ICAM-1 expression in the TNF-α–stimulated cells and in the cells under oxygen-glucose deprivation/reoxygenation (OGD/R) condition. The functional end points of the study indicated that FRS-NPs significantly inhibited monocyte adhesion to the bEND5 cells induced by TNF-α and OGD/R. In conclusion, our approach using RNA nanotechnology for siRNA delivery could be potentially applied for inhibition of inflammation in ischemic stroke and other neuroinflammatory diseases, or diseases affecting endothelium of vasculature.

Cationic liposome-nucleic acid complexes for gene delivery and gene silencing

Cationic liposomes (CLs) are studied worldwide as carriers of DNA and short interfering RNA (siRNA) for gene delivery and gene silencing, and related clinical trials are ongoing. Optimization of transfection efficiency and silencing efficiency by cationic liposome carriers requires a comprehensive understanding of the structures of CL-nucleic acid complexes and the nature of their interactions with cell membranes as well as events leading to release of active nucleic acids within the cytoplasm. Synchrotron x-ray scattering has revealed that CL-nucleic acid complexes spontaneously assemble into distinct liquid crystalline phases including the lamellar, inverse hexagonal, hexagonal, and gyroid cubic phases, and fluorescence microscopy has revealed CL-DNA pathways and interactions with cells. The combining of custom synthesis with characterization techniques and gene expression and silencing assays has begun to unveil structure-function relations in vitro. As a recent example, this review will briefly describe experiments with surface-functionalized PEGylated CL-DNA nanoparticles. The functionalization, which is achieved through custom synthesis, is intended to address and overcome cell targeting and endosomal escape barriers to nucleic acid delivery faced by PEGylated nanoparticles designed for in vivo applications.

A plausible model for bimodal p53 switch in DNA damage response

p53 is a tumor suppressor and the p53 dynamics displays stimulus dependent patterns. Recent evidence suggests a bimodal p53 switch in cell fate decision. However, no theoretical studies have been proposed to investigate bimodal p53 induction. Here we constructed a model and showed that MDM2-p53 mRNA binding might contribute to bimodal p53 switch through an intrinsic positive feedback loop. Lower damage favored pulsing while monotonic increasing was generated with higher damage. Bimodal p53 dynamics was largely influenced by cellular MDM2 and elevated p53/MDM2 ratios with increasing etoposide favor mono-ubiquitination. Our model replicated recent experiments and provided potential insights into dynamic mechanisms of bimodal switch.

Characterization of polyethylene glycol-polyethyleneimine as a vector for alpha-synuclein siRNA delivery to PC12 cells for Parkinson's disease

AIMS

Gene therapy targeting the SNCA gene yields promising results in the treatment of Parkinson's disease (PD). The most challenging issue of the RNAi gene therapy strategy is maintaining efficient delivery without inducing significant toxicity and other adverse effects. This study aimed to characterize polyethylene glycol-polyethyleneimine as a vector for alpha-synuclein siRNA delivery to PC12 cells for Parkinson's disease.

METHODS

The characteristics of PEG-PEI/siSNCA were analyzed via gel retardation assay and assessments of particle size and zeta potential. MTT cytotoxicity assay and flow cytometry were used to detect cytotoxicity and transfection efficiency in PC12 cells. Confocal laser scanning microscopy was employed to examine the intracellular distribution of PEG-PEI/FITC-siSNCA after cellular uptake. RT-PCR and western blotting were used to measure SNCA expression. The MTT cytotoxicity assay was used to study the effect of PEG-PEI/siSNCA on cell viability. The protective effect of PEG-PEI/siSNCA on MPP+-induced apoptosis in PC12 cells was examined via flow cytometry and Hoechst staining.

RESULTS

PEG-PEI/siSNCA complexes were well-developed; they exhibited appropriate particle sizes and zeta potentials at a mass ratio of 5:1. In vitro, PEG-PEI/siSNCA was associated with low cytotoxicity and high transfection efficiency. Complexes were capable of successfully delivering siSNCA into PC12 cells and releasing it from the endosome. Furthermore, PEG-PEI/siSNCA could effectively suppress SNCA mRNA expression and protected cells from death via apoptosis induced by MPP(+) .

CONCLUSIONS

Our results demonstrate that PEG-PEI performs well as a vector for alpha-synuclein siRNA delivery into PC12 cells. Additionally, PEG-PEI/siSNCA complexes were suggested to be able to protect cells from death via apoptosis induced by MPP(+) . These findings suggest that PEG-PEI/siSNCA nanoparticles exhibit remarkable potential as a gene delivery system for Parkinson's disease.

Chikungunya virus: an update on antiviral development and challenges

Chikungunya virus (CHIKV) has re-emerged as a significant public health threat since the 2005 chikungunya fever epidemic in La Réunion. Driven by the medical importance of this virus, as well as the lack of approved antivirals, research into the field of CHIKV antivirals has recently intensified. Potential therapeutics that have been reported to show anti-CHIKV activity in vitro range from known broad-spectrum antivirals like chloroquine to novel strategies involving RNA silencing technology. Although most of the earlier efforts focused on compounds that target host components, some recent studies have reported viral targets such as nonstructural proteins. This article examines the reported in vitro and in vivo efficacies, as well as the therapeutic potential of these antiviral compounds.

Synthetic microRNA-mediated downregulation of Nogo-A in transgenic rats reveals its role as regulator of synaptic plasticity and cognitive function

We have generated a transgenic rat model using RNAi and used it to study the role of the membrane protein Nogo-A in synaptic plasticity and cognition. The membrane protein Nogo-A is expressed in CNS oligodendrocytes and subpopulations of neurons, and it is known to suppress neurite growth and regeneration. The constitutively expressed polymerase II-driven transgene was composed of a microRNA-targeting Nogo-A placed into an intron preceding the coding sequence for EGFP, thus quantitatively labeling cells according to intracellular microRNA expression. The transgenic microRNA in vivo efficiently reduced the concentration of Nogo-A mRNA and protein preferentially in neurons. The resulting significant increase in long-term potentiation in both hippocampus and motor cortex indicates a repressor function of Nogo-A in synaptic plasticity. The transgenic rats exhibited prominent schizophrenia-like behavioral phenotypes, such as perseveration, disrupted prepulse inhibition, and strong withdrawal from social interactions. This fast and efficient microRNA-mediated knockdown provides a way to silence gene expression in vivo in transgenic rats and shows a role of Nogo-A in regulating higher cognitive brain functions.

Liquid crystal assemblies in biologically inspired systems

In this paper, which is part of a collection in honor of Noel Clark's remarkable career on liquid crystal and soft matter research, we present examples of biologically inspired systems, which form liquid crystal (LC) phases with their LC nature impacting biological function in cells or being important in biomedical applications. One area focuses on understanding network and bundle formation of cytoskeletal polyampholytes (filamentous-actin, microtubules, and neurofilaments). Here, we describe studies on neurofilaments (NFs), the intermediate filaments of neurons, which form open network nematic liquid crystal hydrogels in axons. Synchrotron small-angle-x-ray scattering studies of NF-protein dilution experiments and NF hydrogels subjected to osmotic stress show that neurofilament networks are stabilized by competing long-range repulsion and attractions mediated by the neurofilament's polyampholytic sidearms. The attractions are present both at very large interfilament spacings, in the weak sidearm-interpenetrating regime, and at smaller interfilament spacings, in the strong sidearm-interpenetrating regime. A second series of experiments will describe the structure and properties of cationic liposomes (CLs) complexed with nucleic acids (NAs). CL-NA complexes form liquid crystalline phases, which interact in a structure-dependent manner with cellular membranes enabling the design of complexes for efficient delivery of nucleic acid (DNA, RNA) in therapeutic applications.

Lipid-based vectors for siRNA delivery

siRNA therapeutics has developed rapidly and already there are clinical trials ongoing or planned; however, the delivery of siRNA into cells, tissues or organs remains to be a major obstacle. Lipid-based vectors hold the most promising position among non-viral vectors, as they have a similar structure to cell or organelle membranes. But when used in the form of liposomes, these vectors have shown some problems. Therefore, either the nature of lipids themselves or forms used should be improved. As a novel class of lipid like materials, lipidoids have the advantages of easy synthesis and the ability for delivering siRNA to obtain excellent silencing activity. However, the toxicities of lipidoids have not been thoroughly studied. pH responsive lipids have also gained great attention recently, though some of the amine-based lipids are not novel in terms of chemical structures. More complex self-assembly structures, such as LPD (LPH) and LCP, may provide a good solution to siRNA delivery. They have demonstrated controlled particle morphology and size and siRNA delivery activity for both in vitro and in vivo.

Nek2C functions as a tumor promoter in human breast tumorigenesis

The serine⁄threonine kinase Nek2 has been proposed as a requirement for the progression of breast cancer. The aim of this study was to investigate the expression of Nek2C, which is a splice variant of Nek2, and the role it plays in the different stages of breast cancer. We investigated the role of Nek2C in the MCF10 breast cancer cell lines, MCF10A, MCF10AT, MCF10DCIS.com and MCF10CA1a, using RNA interference and plasmid transfection, as well as breast tissue samples of normal breast tissue (NBT), atypical ductal hyperplasia (ADH), ductal carcinoma in situ (DCIS) and invasive ductal carcinoma (IDC). We detected the mRNA Nek2C expression levels in the MCF10 cell lines and in human breast samples. Our results revealed that the mRNA expression of Nek2C was significantly upregulated in the MCF10DCIS.com and MCF10CA1a cell lines as well as in human primary breast cancer tissue (DCIS and IDC). As expected, the Nek2C downregulation, using RNA interference, decreased the survival, invasion and migration of MCF10DCIS.com and MCF10CA1a cells. Consistent with these results, the Nek2C upregulation in MCF10A and MCF10AT cells using plasmid transfection increased the survival ability of these cells. Our results also revealed a correlation between Nek2C mRNA expression levels and tumor grade. Taken together, our findings suggest that Nek2C plays a signicficant role in breast cancer development and that Nek2C inhibition may be a useful therapeutic approach to targeting human breast tumors.

Synthesis and preliminary investigations of the siRNA delivery potential of novel, single-chain rigid cationic carotenoid lipids

The success of nucleic acid delivery requires the development of safe and efficient delivery vectors that overcome cellular barriers for effective transport. Herein we describe the synthesis of a series of novel, single-chain rigid cationic carotenoid lipids and a study of their preliminary in vitro siRNA delivery effectiveness and cellular toxicity. The efficiency of siRNA delivery by the single-chain lipid series was compared with that of known cationic lipid vectors, 3β-[N-(N',N'-dimethylaminoethane)carbamoyl]-cholesterol (DC-Chol) and 1,2-dimyristoyl-sn-glyceryl-3-phosphoethanolamine (EPC) as positive controls. All cationic lipids (controls and single-chain lipids) were co-formulated into liposomes with the neutral co-lipid, 1,2-dioleolyl-sn-glycerol-3-phosphoethanolamine (DOPE). Cationic lipid-siRNA complexes of varying (+/−) molar charge ratios were formulated for delivery into HR5-CL11 cells. Of the five single-chain carotenoid lipids investigated, lipids 1, 2, 3 and 5 displayed significant knockdown efficiency with HR5-CL11 cells. In addition, lipid 1 exhibited the lowest levels of cytotoxicity with cell viability greater than 80% at all (+/−) molar charge ratios studied. This novel, single-chain rigid carotenoid-based cationic lipid represents a new class of transfection vector with excellent cell tolerance, accompanied with encouraging siRNA delivery efficiency.

Effective endogenous gene silencing mediated by pH responsive peptides proceeds via multiple pathways

Cationic amphipathic histidine rich peptides possess high plasmid DNA and siRNA delivery capabilities. To further understand the pH responsive siRNA delivery process and evaluate the capabilities of such peptides we have investigated their ability to mediate specific silencing of endogenous GAPDH gene activity in MCF-7 and A549 cells and compared this with plasmid DNA delivery. A substantial and selective reduction of both GAPDH activity and expression was achieved using pH responsive peptide vectors, which compared favourably with that mediated by commercially available non-viral vectors in terms of efficacy and toxicity. Furthermore, by comparing the efficacy of both gene delivery and silencing mediated by a series of such peptides, their sensitivities to known inhibitors of endocytotic processes, and their route of uptake via confocal live cell imaging, we show that both plasmid DNA and siRNA are internalised via endocytosis. However siRNA entry facilitated by LAH4-L1, proceeds via a cholesterol dependent mechanism, in contrast to DNA transfer which is associated with clathrin dependent endocytosis. Furthermore, using peptides that respond at increasingly acidic pH, we demonstrate that the route of entry for the siRNA that ultimately mediates silencing is peptide specific and whilst some pH responsive peptides promote the escape of labelled siRNA from endosomes, others may promote entry via alternative mechanisms.

Adenovirus-vectored shRNAs targeted to the highly conserved regions of VP1 and 2B in tandem inhibits replication of foot-and-mouth disease virus both in vitro and in vivo

Foot-and-mouth disease is a highly contagious and economically important disease of cloven-hoofed animals. RNA interference (RNAi) can be used as a rapid and specific antiviral approach. It was shown that treatment with recombinant adenovirus (Ad(VP1-2B)) carrying shRNAs targeted to the VP1 and 2B genes of FMDV expressed in tandem had marked antiviral effects against FMDV both in IBRS-2 cells and guinea pigs. Treatment with Ad(VP1-2B) both before and after FMDV infection was most effective in IBRS-2 cells, as the FMDV RNA transcripts could not be detected within 48 h post-challenge (hpc), and the viral RNA copy number at 72 hpc was only 0.02% of that in the positive control group. Delivery of Ad(VP1-2B) reduced significantly the susceptibility of guinea pigs to FMDV infection. All guinea pigs were protected within 3 days post challenge (dpc) when they were injected twice with the same dose of Ad(VP1-2B), and a third treatment with the same dose of Ad(VP1-2B) at 3 dpc was necessary to confer longer lasting protection (up to 6 dpc). In conclusion, application of such a adenovirus vector to inhibit more than one viral gene may be an advantageous method for prevention and therapy of FMDV infection.

Cationic liposome-nucleic acid complexes: liquid crystal phases with applications in gene therapy

Cationic liposome (CL) carriers of nucleic acids are primarily studied because of their applications in gene delivery and gene silencing with CL-DNA and CL-siRNA (short-interfering RNA) complexes, respectively, and their implications to ongoing clinical gene therapy trials worldwide. A series of synchrotron-based small-angle-x-ray scattering studies, dating back to 1997, has revealed that CL-nucleic acid complexes spontaneously assemble into distinct novel liquid crystalline phases of matter. Significantly, transfection efficiency (TE; a measure of expression of an exogenous gene that is transferred into the cell by the lipid carrier) has been found to be dependent on the liquid crystalline structure of complexes, with lamellar complexes showing strong dependence on membrane charge density (σ(M)) and non-lamellar complexes exhibiting TE behavior independent ofσ(M). The review describes our current understanding of the structures of different liquid crystalline CL-nucleic acid complexes including the recently described gyroid cubic phase of CL-siRNA complexes used in gene silencing. It further makes apparent that the long-term goal of developing optimized liquid crystalline CL-nucleic acid complexes for successful medical applications requires a comprehensive understanding of the nature of the interactions of distinctly structured complexes with cell membranes and events leading to release of active nucleic acids within the cell cytoplasm.

Nanogyroids incorporating multivalent lipids: enhanced membrane charge density and pore forming ability for gene silencing

The self-assembly of a custom-synthesized pentavalent cationic lipid (MVL5) and glycerol monooleate (GMO) with small interfering RNA (siRNA) results in the formation of a double-gyroid bicontinuous inverted cubic phase with colocalized lipid/siRNA domains as shown by synchrotron X-ray scattering and fluorescence microscopy. The high charge density (due to MVL5) and positive Gaussian modulus of the GMO-containing membranes confer optimal electrostatic and elastic properties for endosomal escape, enabling efficient siRNA delivery and effective, specific gene silencing.

Silencing of PTK7 in colon cancer cells: caspase-10-dependent apoptosis via mitochondrial pathway

Protein tyrosine kinase-7 (PTK7) is a catalytically inactive receptor tyrosine kinase (RTK). PTK7 is upregulated in many common human cancers, including colon cancer, lung cancer, gastric cancer and acute myeloid leukemia. The reason for this up-regulation is not yet known. To explore the functional role of PTK7, the expression of PTK7 in HCT 116 cells was examined using small interference (siRNA)-mediated gene silencing. Following transfection, the siRNA successfully suppressed PTK7 mRNA and protein expression. Knocking down of PTK7 in HCT 116 cells inhibited cell proliferation compared to control groups and induced apoptosis. Furthermore, this apoptosis was characterized by decreased mitochondrial membrane potential and activation of caspase-9 and -10. Addition of a caspase-10 inhibitor totally blocked this apoptosis, suggesting that caspase-10 may play a critical role in PTK7-knockdown-induced apoptosis, downstream of mitochondria. These observations may indicate a role for PTK7 in cell proliferation and cell apoptosis and may provide a potential therapeutic pathway for the treatment of a variety of cancers.

Design and evaluation of histidine-rich amphipathic peptides for siRNA delivery

PURPOSE

Short linear peptides have a high potential for delivering various drugs with therapeutic potential, including nucleic acids. Recently, we have shown that the cationic amphipathic histidine-rich peptide LAH4 (KKALLALALHHLAHLALHLALALKKA) possesses high plasmid DNA delivery capacities. Since such peptides are thought to efficiently disrupt endosomal membranes, we have tested their ability to deliver small interfering RNA (siRNA) into mammalian cells.

METHODS

Using a human cell line stably transfected with a luciferase-encoding expression vector, we have evaluated the ability of LAH4 and five derivatives thereof to deliver siRNAs and silence gene expression.

RESULTS

The six peptides are all efficient siRNA delivery vehicles whose efficiency in mediating gene silencing in 911-Luc cells was greater than that of commercially available compounds including Lipofectamine, DOTAP and polyethylenimine. In addition, by using the proton pump inhibitor bafilomycin A1, we show that efficient siRNA delivery to the cytosol requires acidification of the endosomes.

CONCLUSIONS

The LAH4 histidine-rich cationic amphipathic peptides represent an interesting and promising family of compounds for siRNA delivery.

Highly efficient gene silencing activity of siRNA embedded in a nanostructured gyroid cubic lipid matrix

RNA interference (RNAi) is an evolutionarily conserved sequence-specific post-transcriptional gene silencing pathway with wide-ranging applications in functional genomics, therapeutics, and biotechnology. Cationic liposome-small interfering RNA (CL-siRNA) complexes have emerged as vectors of choice for delivery of siRNA, which mediates RNAi. However, siRNA delivery by CL-siRNA complexes is often inefficient and accompanied by lipid toxicity. We report the development of CL-siRNA complexes with a novel cubic phase nanostructure, which exhibit efficient silencing at low toxicity. The inverse bicontinuous gyroid cubic nanostructure was unequivocally established from synchrotron X-ray scattering data, while fluorescence microscopy revealed colocalization of lipid and siRNA in complexes. We attribute the efficient silencing to enhanced fusion of complex and endosomal membranes, facilitated by the cubic phase membrane's positive Gaussian modulus, which may enable spontaneous formation of transient pores. The findings underscore the importance of understanding membrane-mediated interactions between CL-siRNA complex nanostructure and cell components in developing CL-based gene silencing vectors.

[siRNA in macular degeneration]

To date aptamers, recombinant antibodies and antibody fragments which interfere specifically in cellular signal transmission by binding transmitters before a signal can be triggered, are the approved therapeutics agents for treatment of ocular angiogenesis. These substances achieve an effective but in most cases temporary inhibition of vascular growth and permeability. Other alternatives to inhibit cellular communication, such as tyrosine kinase inhibition or especially post-transcriptional gene silencing by degradation of messenger RNA (mRNA) induced by small interfering RNA (siRNA) are being evaluated in ongoing studies. In this overview issues related to mechanisms and molecule design, as well as clinical applications and the first clinical experience in ophthalmology reported on siRNA will be discussed.

siRNA-mediated knockdown of VEGF-A, VEGF-C and VEGFR-3 suppresses the growth and metastasis of mouse bladder carcinoma in vivo

The growth of solid tumors is highly dependent on the formation of new blood and/or lymph vessels. Furthermore, metastases often disperse via newly formed blood or lymphatic vessels within the tumor, particularly in the case of epithelium-derived tumors. Since vascular endothelial growth factor (VEGF) signaling plays a vital role in angiogenesis and lymphangiogenesis, we used the small interfering RNA (siRNA) approach to selectively down-regulate VEGF-A, VEGF-C or VEGF receptor 3 (VEGFR-3) expression in bladder transitional carcinoma cells derived from T739 mice in an attempt to suppress tumor growth and metastasis in vivo. The synthetic siRNA was introduced into the tumor tissues by in vivo electroporation. The knockdown of VEGF-A, VEGF-C and VEGFR-3 expression significantly delayed tumor growth and reduced tumor metastasis compared to the negative controls. Thus, electroporation-mediated siRNA delivery to block the VEGF signaling pathway may provide a novel approach for the treatment or prevention of solid tumor growth and metastasis.

Multifunctional siRNA delivery system: polyelectrolyte complex micelles of six-arm PEG conjugate of siRNA and cell penetrating peptide with crosslinked fusogenic peptide

For therapeutic applications of small interfering RNA (siRNA), serum stability, enhanced cellular uptake, and facile endosome escape are key issues for designing carriers. In this study, green fluorescent protein (GFP) siRNA was conjugated to a six-arm polyethylene glycol (PEG) derivative via a reducible disulfide linkage (6PEG-siRNA). The 6PEG-siRNA conjugate was also functionalized with a cell penetrating peptide, Hph1 to enhance its cellular uptake property (6PEG-siRNA-Hph1). The 6PEG-siRNA-Hph1 conjugate was electrostatically complexed with cationic self-crosslinked fusogenic KALA peptide (cl-KALA) to form multifunctional polyelectrolyte complex micelles for gene silencing. The resultant siRNA complex formulation with multiple PEG chains showed superior physical stability and resistance to enzymatic degradation. The 6PEG-siRNA-Hph1/cl-KALA complexes exhibited enhanced GFP gene silencing efficiency for MDA-MB-435 cells in the serum containing condition. The current reducible and multifunctional polyelectrolyte complex micelles are expected to have high potential for efficient delivery of therapeutic siRNA.

Novel combination treatment for colorectal cancer using Nek2 siRNA and cisplatin

Nek2 (NIMA-related kinase 2) is involved in cell division and mitotic regulation by centrosome splitting. We previously reported that Nek2 depletion causes growth suppression and cell death in cholangiocarcinoma and breast cancer cells. In this report, we examine the effect of a combination treatment using Nek2 siRNA with the cytotoxic chemotherapeutic agent cisplatin (CDDP) on colorectal cancer. Nek2 was overexpressed in all colorectal cancer cell lines examined (HCT-15, DLD-1, Colo205, and Colo320). Nek2 short-interfering RNA (siRNA) resulted in the inhibition of cell proliferation and the induction of apoptosis in vitro. Nek2 siRNA suppressed tumor growth compared to control siRNA in a xenograft mouse model. To investigate the potential utility of Nek2 siRNA for clinical cancer therapy, we examine the effect of a combination treatment using Nek2 siRNA with CDDP on colorectal cancer. The combined administration of both Nek2 siRNA and CDDP inhibited cell proliferation and induced apoptotic cell death in vitro. Furthermore, the combined administration of both Nek2 siRNA and CDDP suppressed tumor growth compared to either the single administration of Nek2 siRNA or the combined administration of control siRNA and CDDP. Our results suggest that combination treatment using Nek2 siRNA and chemotherapeutic agents may be an effective therapeutic option for colorectal cancer.

Infrared multiphoton dissociation of small-interfering RNA anions and cations

Infrared multiphoton dissociation (IRMPD) on a linear ion trap mass spectrometer is applied for the sequencing of small interfering RNA (siRNA). Both single-strand siRNAs and duplex siRNA were characterized by IRMPD, and the results were compared with that obtained by traditional ion trap-based collision induced dissociation (CID). The single-strand siRNA anions were observed to dissociate via cleavage of the 5' P-O bonds yielding c- and y-type product ions as well as undergo neutral base loss. Full sequence coverage of the siRNA anions was obtained by both IRMPD and CID. While the CID mass spectra were dominated by base loss ions, accounting for approximately 25% to 40% of the product ion current, these ions were eliminated through secondary dissociation by increasing the irradiation time in the IRMPD mass spectra to produce higher abundances of informative sequence ions. With longer irradiation times, however, internal ions corresponding to cleavage of two 5' P-O bonds began to populate the product ion mass spectra as well as higher abundances of [a - Base] and w-type ions. IRMPD of siRNA cations predominantly produced c- and y-type ions with minimal contributions of [a - Base] and w-type ions to the product ion current; the presence of only two complementary series of product ions in the IRMPD mass spectra simplified spectral interpretation. In addition, IRMPD produced high abundances of protonated nucleobases, [G + H](+), [A + H](+), and [C + H](+), which were not detected in the CID mass spectra due to the low-mass cut-off associated with conventional CID in ion traps. CID and IRMPD using short irradiation times of duplex siRNA resulted in strand separation, similar to the dissociation trends observed for duplex DNA. With longer irradiation times, however, the individual single-strands underwent secondary dissociation to yield informative sequence ions not obtained by CID.