RNA interference-mediated gene silencing of pleiotrophin through polyethylenimine-complexed small interfering RNAs in vivo exerts antitumoral effects in glioblastoma xenografts

ApoE-functionalization of nanoparticles for targeted brain delivery-a feasible method for polyplexes?

The blood-brain barrier (BBB) poses a major obstacle in the treatment of all types of central nervous system (CNS) diseases. Small interfering RNA (siRNA) offers in principle a promising therapeutic approach by downregulating disease-related genes via RNA interference. However, the BBB is a formidable barrier for macromolecules such as nucleic acids. In an effort to develop a brain-targeted strategy for siRNA delivery systems formed by electrostatic interactions with cationic polymers (polyplexes (PXs)), we investigated the suitability of the well-known surfactant-based approach for Apolipoprotein E (ApoE)-functionalization of nanoparticles (NPs). The aim of this present work was to investigate if ApoE coating of siRNA PXs formed with cationic branched 25-kDa poly(ethyleneimine) (b-PEI) and nylon-3 polymers without or after precoating with polysorbate 80 (PS 80) would promote successful delivery across the BBB. We utilized highly hydrophobic NM0.2/CP0.8 nylon-3 polymers to evaluate the effects of hydrophobic cyclopentyl (CP) subunits on ApoE binding efficacy and observed successful ApoE binding with and without PS 80 precoating to the nylon-3 but not the PEI polyplexes. Accordingly, ApoE-coated nylon-3 polyplexes showed significantly increased uptake and gene silencing in U87 glioma cells but no benefit in vivo. In conclusion, further optimization of ApoE-functionalized polyplexes and more sophisticated in vitro models are required to achieve more successful in vitro-in vivo translation in future approaches.

Pulmonary siRNA Delivery with Sophisticated Amphiphilic Poly(Spermine Acrylamides) for the Treatment of Lung Fibrosis

RNA interference (RNAi) is an efficient strategy to post-transcriptionally silence gene expression. While all siRNA drugs on the market target the liver, the lung offers a variety of currently undruggable targets, which can potentially be treated with RNA therapeutics. To achieve this goal, the synthesis of poly(spermine acrylamides) (P(SpAA) is reported herein. Polymers are prepared via polymerization of N-acryloxysuccinimide (NAS) and afterward this active ester is converted into spermine-based pendant groups. Copolymerizations with decylacrylamide are employed to increase the hydrophobicity of the polymers. After deprotection, polymers show excellent siRNA encapsulation to obtain perfectly sized polyplexes at very low polymer/RNA ratios. In vitro 2D and 3D cell culture, ex vivo and in vivo experiments reveal superior properties of amphiphilic spermine-copolymers with respect to delivery of siRNA to lung cells in comparison to commonly used lipid-based transfection agents. In line with the in vitro results, siRNA delivery to human lung explants confirm more efficient gene silencing of protease-activated receptor 2 (PAR2), a G protein-coupled receptor involved in fibrosis. This study reveals the importance of the balance between efficient polyplex formation, cellular uptake, gene knockdown, and toxicity for efficient siRNA delivery in vitro, in vivo, and in fibrotic human lung tissue ex vivo.

Small interfering RNA: Discovery, pharmacology and clinical development-An introductory review

Post-transcriptional gene silencing targets and degrades mRNA transcripts, silencing the expression of specific genes. RNA interference technology, using synthetic structurally well-defined short double-stranded RNA (small interfering RNA [siRNA]), has advanced rapidly in recent years. This introductory review describes the utility of siRNA, by exploring the underpinning biology, pharmacology, recent advances and clinical developments, alongside potential limitations and ongoing challenges. Mediated by the RNA-induced silencing complex, siRNAs bind to specific complementary mRNAs, which are subsequently degraded. siRNA therapy offers advantages over other therapeutic approaches, including ability of specifically designed siRNAs to potentially target any mRNA and improved patient adherence through infrequent administration associated with a very long duration of action. Key pharmacokinetic and pharmacodynamic challenges include targeted administration, poor tissue penetration, nuclease inactivation, rapid renal elimination, immune activation and off-target effects. These have been overcome by chemical modification of siRNA and/or by utilising a range of delivery systems, increasing bioavailability and stability to allow successful clinical translation. Patisiran (hereditary transthyretin-mediated amyloidosis) was the first licensed siRNA, followed by givosiran (acute hepatic porphyria), lumasiran (primary hyperoxaluria type 1) and inclisiran (familial hypercholesterolaemia), which all use N-acetylgalactosamine (GalNAc) linkage for effective liver-directed delivery. Others are currently under development for indications varying from rare genetic diseases to common chronic non-communicable diseases (hypertension, cancer). Technological advances are paving the way for broader clinical use. Ongoing challenges remain in targeting organs beyond the liver and reaching special sites (e.g., brain). By overcoming these barriers, siRNA therapy has the potential to substantially widen its therapeutic impact.

Insights on prospects of nano-siRNA based approaches in treatment of Cancer

siRNA interference, commonly referred to as gene silence, is a biological mechanism that inhibits gene expression in disorders such as cancer. It may enhance the precision, efficacy, and stability of medicines, especially genetic therapies to some extent. However, obstacles such as the delivery of oligonucleotide drugs to inaccessible areas of the body and the prevalence of severe side effects must be overcome. To maximize their potential, it is thus essential to optimize their distribution to target locations and limit their toxicity to healthy cells. The action of siRNA may be harnessed to delete a similar segment of mRNA that encodes a protein that causes sickness. The absence of an efficient delivery mechanism that shields siRNA from nuclease degradation, delivers it to cancer cells and releases it into the cytoplasm of specific cancer cells without causing side effects is currently the greatest obstacle to the practical implementation of siRNA therapy. This article focuses on combinations of siRNA with chemotherapeutic drug delivery systems for the treatment of cancer and gives an overview of several nanocarrier formulations in both research and clinical applications.

Small Interfering RNA for Gliomas Treatment: Overcoming Hurdles in Delivery

Gliomas are central nervous system tumors originating from glial cells, whose incidence and mortality rise in coming years. The current treatment of gliomas is surgery combined with chemotherapy or radiotherapy. However, developing therapeutic resistance is one of the significant challenges. Recent research suggested that small interfering RNA (siRNA) has excellent potential as a therapeutic to silence genes that are significantly involved in the manipulation of gliomas’ malignant phenotypes, including proliferation, invasion, metastasis, therapy resistance, and immune escape. However, it is challenging to deliver the naked siRNA to the action site in the cells of target tissues. Therefore, it is urgent to develop delivery strategies to transport siRNA to achieve the optimal silencing effect of the target gene. However, there is no systematic discussion about siRNAs’ clinical potential and delivery strategies in gliomas. This review mainly discusses siRNAs’ delivery strategies, especially nanotechnology-based delivery systems, as a potential glioma therapy. Moreover, we envisage the future orientation and challenges in translating these findings into clinical applications.

Biotechnological Evolution of siRNA Molecules: From Bench Tool to the Refined Drug

The depth and versatility of siRNA technologies enable their use in disease targets that are undruggable by small molecules or that seek to achieve a refined turn-off of the genes for any therapeutic area. Major extracellular barriers are enzymatic degradation of siRNAs by serum endonucleases and RNAases, renal clearance of the siRNA delivery system, the impermeability of biological membranes for siRNA, activation of the immune system, plasma protein sequestration, and capillary endothelium crossing. To overcome the intrinsic difficulties of the use of siRNA molecules, therapeutic applications require nanometric delivery carriers aiming to protect double-strands and deliver molecules to target cells. This review discusses the history of siRNAs, siRNA design, and delivery strategies, with a focus on progress made regarding siRNA molecules in clinical trials and how siRNA has become a valuable asset for biopharmaceutical companies.

Targeting nucleic acid-based therapeutics to tumors: Challenges and strategies for polyplexes

The current medical reality of cancer gene therapy is reflected by more than ten approved products on the global market, including oncolytic and other viral vectors and CAR T-cells as ex vivo gene-modified cell therapeutics. The development of synthetic antitumoral nucleic acid therapeutics has been proceeding at a lower but steady pace, fueled by a plethora of alternative nucleic acid platforms (from various antisense oligonucleotides, siRNA, microRNA, lncRNA, sgRNA, to larger mRNA and DNA) and several classes of physical and chemical delivery technologies. This review summarizes the challenges and strategies for tumor-targeted nucleic acid delivery. Focusing primarily on polyplexes (polycation complexes) as nanocarriers, delivery options across multiple barriers into tumor cells are illustrated.

Liposome-Polymer Complex for Drug Delivery System and Vaccine Stabilization

Liposomes have been used extensively as micro- and nanocarriers for hydrophobic or hydrophilic molecules. However, conventional liposomes are biodegradable and quickly eliminated, making it difficult to be used for delivery in specific routes, such as the oral and systemic routes. One way to overcome this problem is through complexation with polymers, which is referred to as a liposome complex. The use of polymers can increase the stability of liposome with regard to pH, chemicals, enzymes, and the immune system. In some cases, specific polymers can condition the properties of liposomes to be explicitly used in drug delivery, such as targeted delivery and controlled release. These properties are influenced by the type of polymer, crosslinker, interaction, and bond in the complexation process. Therefore, it is crucial to study and review these parameters for the development of more optimal forms and properties of the liposome complex. This article discusses the use of natural and synthetic polymers, ways of interaction between polymers and liposomes (on the surface, incorporation in lamellar chains, and within liposomes), types of bonds, evaluation standards, and their effects on the stability and pharmacokinetic profile of the liposome complex, drugs, and vaccines. This article concludes that both natural and synthetic polymers can be used in modifying the structure and physicochemical properties of liposomes to specify their use in targeted delivery, controlled release, and stabilizing drugs and vaccines.

Nucleic acid delivery for therapeutic applications

Recent medical advances have exploited the ability to address a given disease at the underlying level of transcription and translation. These treatment paradigms utilize nucleic acids - including short interfering RNA (siRNA), microRNA (miRNA), antisense oligonucleotides (ASO), and messenger RNA (mRNA) - to achieve a desired outcome ranging from gene knockdown to induced expression of a selected target protein. Towards this end, numerous strategies for encapsulation or stabilization of various nucleic acid structures have been developed in order to achieve intracellular delivery. In this review, we discuss several therapeutic applications of nucleic acids directed towards specific diseases and tissues of interest, in particular highlighting recent technologies which have reached late-stage clinical trials and received FDA approval.

Extension in the approaches to treat cancer through siRNA system: a beacon of hope in cancer therapy

Along with the evolutionary breakthrough of RNA interference and the applicability for gene knockdown, a subsequent development in siRNA-based therapeutics has been attained. The gene therapy based on RNAi is in transition progress from the research aspects to clinical base. Being a potent tool, siRNA is used as therapeutic against several disorders. Cancer which is one of the deadliest diseases is now treated with an advanced mechanism of siRNA delivery inside the genome, leading to gene silencing; thereby, blocking translation of gene to form protein. siRNA tool delivers remedial effects with the advantages of safe delivery and efficiency. Despite its merits, barriers including instability at physiological conditions, lack of ability to cross biological membranes, off-targets, and safety are also associated with siRNA delivery system. The gene silencing efficiency values both in vitro and in vivo reported in the past years have been reviewed by material type (lipid, polymer, silica, porous silicon, and metal). This review presents a deep insight in the development of targeted delivery of siRNA. Since several clinical trials have also been performed regarding the siRNA delivery against cancer, it can also be stated that the delivery system should be good enough to achieve effective siRNA drug development.

Overcoming Barriers for siRNA Therapeutics: From Bench to Bedside

The RNA interference (RNAi) pathway possesses immense potential in silencing any gene in human cells. Small interfering RNA (siRNA) can efficiently trigger RNAi silencing of specific genes. FDA Approval of siRNA therapeutics in recent years garnered a new hope in siRNA therapeutics. However, their therapeutic use is limited by several challenges. siRNAs, being negatively charged, are membrane-impermeable and highly unstable in the systemic circulation. In this review, we have comprehensively discussed the extracellular barriers, including enzymatic degradation of siRNAs by serum endonucleases and RNAases, rapid renal clearance, membrane impermeability, and activation of the immune system. Besides, we have thoroughly described the intracellular barriers such as endosomal trap and off-target effects of siRNAs. Moreover, we have reported most of the strategies and techniques in overcoming these barriers, followed by critical comments in translating these molecules from bench to bedside.

HER-2/neu and MYC gene silencing in breast cancer: therapeutic potential and advancement in nonviral nanocarrier systems

Globally, breast cancer is the second leading cause of cancer-related mortality among women, with approximately 1.4 million new cases diagnosed annually. Associated genetic perturbations are emerging in the face of intense scientific enquiry, facilitating its classification, prognostication and treatment. RNAi, utilizing siRNA, is a powerful treatment strategy to silence disease-causing genes. However, therapeutic siRNA instability and poor cellular uptake have limited its clinical application, necessitating the use of nanocarriers. In this review, we highlight the RNAi mechanism, HER-2/neu and MYC as breast cancer gene targets, and nonviral nanocarriers as potentially safe and efficient delivery systems.

Pleiotrophin: Activity and mechanism

Pleiotrophin (PTN) is a potent mitogenic cytokine with a high affinity for the polysaccharide glycosaminoglycan (GAG). Although it is most strongly associated with neural development during embryogenesis and the neonatal period, its expression has also been linked to a plethora of other physiological events including cancer metastasis, angiogenesis, bone development, and inflammation. A considerable amount of research has been carried out to understand the mechanisms by which PTN regulates these events. In particular, PTN has now been shown to bind a diverse collection of receptors including many GAG-containing proteoglycans. These interactions lead to the activation of many intracellular kinases and, ultimately, activation and transformation of cells. Structural studies of PTN in complex with both GAG and domains from its non-proteoglycan receptors reveal a binding mechanism that relies on electrostatic interactions and points to PTN-induced receptor oligomerization as one of the possible ways PTN uses to control cellular functions.

Promising approaches of small interfering RNAs (siRNAs) mediated cancer gene therapy

RNA interference (RNAi) has extensive potential to revolutionize every aspect of clinical application in biomedical research. One of the promising tools is the Small interfering RNA (siRNA) molecules within a cellular component. Principally, siRNA mediated innovative advances are increasing rapidly in support of cancer diagnosis and therapeutic purposes. Conversely, it has some delivery challenges to the site of action within the cells of a target organ, due to the progress of nucleic acids engineering and advance material science research contributing to the exceptional organ-specific targeted therapy. This siRNA based therapeutic technique definitely favors a unique and effective prospect to cancer patients. Herein, the significant drive also takes to review and summarize the major organ specific targets of diverse siRNAs based gene silencing mechanism. This machinery promisingly served as the inhibitor components for cancer development in the human model. Furthermore, the focus is also given to current applications on siRNA based quantifiable therapy leading to the silencing of cancer related gene expression in a sequence dependent and selective manner for cancer treatment. That might be a potent tool against the traditional chemotherapy techniques. Therefore, the siRNA mediated cancer gene therapy definitely require sharp attention like future weapons in opposition to cancer by the method of non-invasive siRNA delivery and effective gene silencing approaches.

The Impact of Nylon-3 Copolymer Composition on the Efficiency of siRNA Delivery to Glioblastoma Cells

Glioblastoma multiforme is a devastating disease that has attracted enormous attention due to poor prognosis and high recurrence. Small interfering RNA (siRNA) in principle offers a promising therapeutic approach by the downregulation of disease-related genes via RNA interference. For efficient siRNA delivery to target sites, cationic polymers are often used in preclinical studies for the protection of siRNA and complex formation based on electrostatic interactions. In an effort to develop biocompatible and efficient nanocarriers with a translational outlook for optimal gene silencing at reduced toxicity, we synthesized two sets of nylon-3 copolymers with variable cationic content (DM or NM monomer) and hydrophobic subunits (CP monomer) and evaluated their suitability for in vitro siRNA delivery into glioblastoma cells. DM_0.4/CP_0.6 and NM_0.4/CP_0.6 polymers with similar subunit ratios were synthesized to compare the effect of different cationic subunits. Additionally, we utilized NM_0.2/CP_0.8 polymers to evaluate the impact of the different hydrophobic content in the polymer chain. The siRNA condensation ability and polymer–siRNA complex stability was evaluated by unmodified and modified SYBR gold assays, respectively. Further physicochemical characteristics, e.g., particle size and surface charge, were evaluated by dynamic light scattering and laser Doppler anemometry, whereas a relatively new method for polyplex size distribution analysis—tunable resistive pulse sensing—was additionally developed and compared to DLS measurements. Transfection efficiencies, the route of cell internalization, and protein knockdown abilities in glioblastoma cells were investigated by flow cytometry. Furthermore, cellular tolerability was evaluated by MTT and LDH assays. All the polymers efficiently condensed siRNA at N/P ratios of three, whereas polymers with NM cationic subunits demonstrated smaller particle size and lower polyplex stability. Furthermore, NM_0.2/CP_0.8 polyplexes with the highest hydrophobic content displayed significantly higher cellular internalization in comparison to more cationic formulations and successful knockdown capabilities. Detailed investigations of the cellular uptake route demonstrated that these polyplexes mainly follow clathrin-mediated endocytotic uptake mechanisms, implying high interaction capacity with cellular membranes. Taken together with conducive toxicity profiles, highly hydrophobic nylon-3 polymers provide an appropriate siRNA delivery agent for the potential treatment of glioblastoma.

Biodrug Suppresses Breast and Colorectal Cancer in Murine Models

RNA interference (RNAi) remains one of the most promising and emerging strategies for the effective cancer treatment due to its high target specificity and greater potency. However, it is hindered due to lack of appropriate targeting technologies. Therefore, there is an imminent need to develop specific and robust delivery systems for successful gene silencing. Nanotechnology-based strategies have been in place to combat the shortcomings associated with viral-based delivery systems. Herein we describe protocols for successful in vitro and in vivo delivery of gene-specific nucleic acids such as siRNAs and shRNAs using PEI-PGMA nanoparticles for efficient cancer therapy.

A T7 autogene-based hybrid mRNA/DNA system for long-term shRNA expression in cytoplasm without inefficient nuclear entry

The transient silencing effects currently demonstrated by nonviral siRNA delivery systems limit the therapeutic utility of RNAi, but it remains a technical challenge to prolong duration of gene silencing. We have developed a T7 autogene-based hybrid mRNA/DNA system to enable long-term expression of shRNA in cytoplasm in vitro and in vivo. This hybrid mRNA/DNA system consists of T7 polymerase (T7pol) mRNA, pT7/shRNA-encoding DNA fragment and T7 autogene plasmid, and it can generate higher levels of T7pol proteins, compared to pCMV-triggering T7 autogene system, especially without the need of nuclear entry of any gene. A large amount of T7pol proteins produced are used to induce pT7-driven expression of shRNA in cytoplasm, and through cellular processing of RNA hairpins, mature siRNAs are generated for more than 13 days. We here demonstrate that a single liposomal delivery of this hybrid system leads to the long-term silencing effects in vitro and in vivo, in contrast to the conventional siRNA methods relying on the repeated administrations every 2 or 3 days. These sustainable shRNA expression properties in cytoplasm can provide an efficient strategy to address the limitations caused by shRNA-encoding plasmid DNA systems such as low nuclear entry efficiency and short-term silencing effect. The development of long-term shRNA expression system in vivo could scale down administration frequency of RNAi therapeutics in the treatment of chronic diseases, thereby increasing its clinical utility.

Macrophage-specific nanotechnology-driven CD163 overexpression in human macrophages results in an M2 phenotype under inflammatory conditions

M1 macrophages release proinflammatory factors during inflammation. They transit to an M2 phenotype and release anti-inflammatory factors to resolve inflammation. An imbalance in the transition from M1 to M2 phenotype in macrophages contributes to the development of persistent inflammation. CD163, a member of the scavenger receptor cysteine-rich family, is an M2 macrophage marker. The functional role of CD163 during the resolution of inflammation is not completely known. We postulate that CD163 contributes to the transition from M1 to M2 phenotype in macrophages. We induced CD163 gene in THP-1 and primary human macrophages using polyethylenimine nanoparticles grafted with a mannose ligand (Man-PEI). This nanoparticle specifically targets cells of monocytic origin via mannose receptors. Cells were challenged with a single or a double stimulation of lipopolysaccharide (LPS). A CD163 or empty plasmid was complexed with Man-PEI nanoparticles for cell transfections. Quantitative RT-PCR, immunocytochemistry, and ELISAs were used for molecular assessments. CD163-overexpressing macrophages displayed reduced levels of tumor necrosis factor-alpha (TNF)-α and monocytes chemoattractant protein (MCP)-1 after a single stimulation with LPS. Following a double stimulation paradigm, CD163-overexpressing macrophages showed an increase of interleukin (IL)-10 and IL-1ra and a reduction of MCP-1. This anti-inflammatory phenotype was partially blocked by an anti-CD163 antibody (effects on IL-10 and IL-1ra). A decrease in the release of TNF-α, IL-1β, and IL-6 was observed in CD163-overexpressing human primary macrophages. The release of IL-6 was blocked by an anti-CD163 antibody in the CD163-overexpressing group. Our data show that the induction of the CD163 gene in human macrophages under inflammatory conditions produces changes in cytokine secretion in favor of an anti-inflammatory phenotype. Targeting macrophages to induce CD163 using cell-directed nanotechnology is an attractive and practical approach for inflammatory conditions that could lead to persistent pain, i.e. major surgeries, burns, rheumatoid arthritis, etc.

EGF receptor targeted lipo-oligocation polyplexes for antitumoral siRNA and miRNA delivery

Antitumoral siRNA and miRNA delivery was demonstrated by epidermal growth factor receptor (EGFR) targeted oligoaminoamide polyplexes. For this purpose, the T-shaped lipo-oligomer 454 was used to complex RNA into a core polyplex, which was subsequently functionalized with the targeting peptide ligand GE11 via a polyethylene glycol (PEG) linker. To this end, free cysteines on the surface of 454 polyplex were coupled with a maleimide-PEG-GE11 reagent (Mal-GE11). Resulting particles with sizes of 120-150 nm showed receptor-mediated uptake into EGFR-positive T24 bladder cancer cells, MDA-MB 231 breast cancer cells and Huh7 liver cancer cells. Furthermore, these formulations led to ligand-dependent gene silencing. RNA interference (RNAi) triggered antitumoral effects were observed for two different therapeutic RNAs, a miRNA-200c mimic or EG5 siRNA. Using polyplexes modified with a ratio of 0.8 molar equivalents of Mal-GE11, treatment of T24 or MDA-MB 231 cancer cells with miR-200c led to the expected decreased proliferation and migration, changes in cell cycle and enhanced sensitivity towards doxorubicin. Delivery of EG5 siRNA into Huh7 cells resulted in antitumoral activity with G2/M arrest, triggered by loss of mitotic spindle separation and formation of mono-astral spindles. These findings demonstrate the potential of GE11 ligand-containing RNAi polyplexes for cancer treatment.

Complex Coacervation-Integrated Hybrid Nanoparticles Increasing Plasmid DNA Delivery Efficiency in Vivo

Many polycation-based gene delivery vehicles have limited in vivo transfection efficiency because of their excessive exterior positive charges and/or PEGylation, both of which could result in premature dissociation and poor cellular uptake and trafficking. Here, we reported novel hybrid PEGylated nanoparticles (HNPs) that are composed of (a) poly(ethylene glycol)-b-poly(aspartate)-adamantane (PEG-P(asp)-Ad) constituting the outer PEG layer to provide colloidal stability; (b) poly(ethylenimine)_10K (PEI_10K) forming complex coacervate with P(asp) as the cross-linked cage preventing premature dissociation; (c) cyclodextrin-decorated PEI_10K (PEI_10K-CD) forming the core with reporter plasmid DNA (pDNA). These HNPs exhibited an increased stability and higher in vitro transfection efficiency compared to traditional PEGylated nanoparticles (PEG-NP). Intratumoral injections further demonstrated that HNPs were able to successfully deliver pDNAs into tumors, while PEG-NP and PEI_25K had only negligible delivery efficiencies. Moreover, HNPs' in vivo stability and pDNA delivery capability post intravenous injection were also confirmed by live animal bioluminescence and fluorescence image analysis. It is likely that the coacervation integration at the interface of PEI_10K-CD/pDNA core and the PEG shell attributed to the significantly improved in vivo transfection efficiency of HNPs over PEG-NP and PEI_25K. This study suggests that the HNP has the potential for in vivo gene delivery applications with significantly improved gene transfection efficiency.

Efficient delivery of therapeutic siRNA into glioblastoma cells using multifunctional dendrimer-entrapped gold nanoparticles

AIM

To synthesize the arginine-glycine-aspartic (RGD) functionalized dendrimer-entrapped gold nanoparticles (Au DENPs) for siRNA delivery to induce gene silencing of cancer cells in vitro and in vivo.

MATERIALS & METHODS

Au DENPs modified with RGD peptide via a polyethylene glycol spacer were used as a vector of two distinct small interfering RNAs (siRNAs) (VEGFvascular endothelial growth factor siRNA and B-cell lymphoma/leukemia-2 siRNA), and the physicochemical properties, cytocompatibility and transfection efficiency of Au DENP/siRNA polyplexes were characterized.

RESULTS

The Au DENP/siRNA polyplexes with good cytocompatibility and highly efficient transfection capacity can be used for the transfection of siRNAs.

CONCLUSION

The developed functional RGD-modified Au DENPs may be used for efficient gene therapy of different types of cancer.

Evaluation of a nanotechnology-based approach to induce gene-expression in human THP-1 macrophages under inflammatory conditions

Macrophages orchestrate the initiation and resolution of inflammation by producing pro- and anti-inflammatory products. An imbalance in these mediators may originate from a deficient or excessive immune response. Therefore, macrophages are valid therapeutic targets to restore homeostasis under inflammatory conditions. We hypothesize that a specific mannosylated nanoparticle effectively induces gene expression in human macrophages under inflammatory conditions without undesirable immunogenic responses. THP-1 macrophages were challenged with lipopolysaccharide (LPS, 5μg/mL). Polyethylenimine (PEI) nanoparticles grafted with a mannose receptor ligand (Man-PEI) were used as a gene delivery method. Nanoparticle toxicity, Man-PEI cellular uptake rate and gene induction efficiency (GFP, CD14 or CD68) were studied. Potential immunogenic responses were evaluated by measuring the production of tumor necrosis factor-alpha (TNF-α), Interleukin (IL)-6 and IL-10. Man-PEI did not produce cytotoxicity, and it was effectively up-taken by THP-1 macrophages (69%). This approach produced a significant expression of GFP (mRNA and protein), CD14 and CD68 (mRNA), and transiently and mildly reduced IL-6 and IL-10 levels in LPS-challenged macrophages. Our results indicate that Man-PEI is suitable for inducing an efficient gene overexpression in human macrophages under inflammatory conditions with limited immunogenic responses. Our promising results set the foundation to test this technology to induce functional anti-inflammatory genes.

Tumor-suppressive effects of atelocollagen-conjugated hsa-miR-520d-5p on un-differentiated cancer cells in a mouse xenograft model

Background

We previously demonstrated that hsa-miR-520d-5p can convert cancer cells into induced pluripotent stem cells (iPSCs) or mesenchymal stem cells (MSCs) via a demethylation process and p53 upregulation in vivo. Additionally, we have reported the non-tumorigenic effect of miR-520d-5p on normal human cells, including fibroblasts.

Methods

We used atelocollagen-conjugated miR-520d-5p (520d/atelocollagen) to confirm the possibility of a therapeutic effect on cancer cells. We traced the size and signal intensity of GFP-expressing tumors in mice each week, beginning 4 weeks after subcutaneous inoculation.

Results

520d/atelocollagen treatment suppressed tumor growth by greater than 80 % each week relative to controls and resulted in an approximately 30 % disappearance of tumors. In mice whose tumors disappeared, the existence of human genomic material at the injection site was examined by quantitative Alu-PCR, and we confirmed the co-existence of both species-derived cells. In every site where a tumor disappeared in immunodeficient mice, GFP protein was expressed in the connective tissues, and approximately 0.1 % of the extracted DNA contained human genomic material. We could not identify any adverse effects in vivo.

Conclusions

This is the first report to confirm an inhibitory effect of 520d/atelocollagen on cancer cells in vivo. The development of optimized modifications of this carrier is expected to enhance the efficiency of entry into tumor cells and the induction of its inhibitory effect.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2467-y) contains supplementary material, which is available to authorized users.

RNAi therapeutics for brain cancer: current advancements in RNAi delivery strategies

Malignant primary brain tumors are aggressive cancerous cells that invade the surrounding tissues of the central nervous system. The current treatment options for malignant brain tumors are limited due to the inability to cross the blood-brain barrier. The advancements in current research has identified and characterized certain molecular markers that are essential for tumor survival, progression, metastasis and angiogenesis. These molecular markers have served as therapeutic targets for the RNAi based therapies, which enable site-specific silencing of the gene responsible for tumor proliferation. However, to bring about therapeutic success, an efficient delivery carrier that can cross the blood-brain barrier and reach the targeted site is essential. The current review focuses on the potential of targeted, non-viral and viral particles containing RNAi therapeutic molecules as delivery strategies specifically for brain tumors.

Systemic delivery of siRNA by T7 peptide modified core-shell nanoparticles for targeted therapy of breast cancer

Systemic delivery of siRNA is the most challenging step to transfer RNAi to clinical application for breast cancer therapy. In this study, the tumor targeted, T7 peptide modified core-shell nanoparticles (named as T7-LPC/siRNA NPs) were constructed to achieve effective systemic delivery of siRNA. The core-shell structure of T7-LPC/siRNA NPs enables them to encapsulate siRNA in the core and protect it from RNase degradation during circulation. In vitro cellular uptake and gene silencing experiments demonstrated that T7-LPC/siEGFR NPs could deliver EGFR siRNA into breast cancer cells through receptor mediated endocytosis and effectively down-regulate the EGFR expression. In vivo distribution study proved the T7-LPC/siRNA NPs could deliver fluorescence labeled siRNA to the tumor site more efficiently than the non-targeted PEG-LPC/siRNA NPs after intravenous administration. Furthermore, the experiments of in vivo tumor therapy confirmed that intravenous administration of T7-LPC/siEGFR NPs led to an effective EGFR down-regulation and an obvious inhibition of breast tumor growth, with little activation of immune responses and negligible body weight loss. These results suggested that T7-LPC/siRNA NPs could be an effective and safe systemic siRNA delivery system for RNAi-based breast cancer therapy.

Pleiotrophin promotes vascular abnormalization in gliomas and correlates with poor survival in patients with astrocytomas

Glioblastomas are aggressive astrocytomas characterized by endothelial cell proliferation and abnormal vasculature, which can cause brain edema and increase patient morbidity. We identified the heparin-binding cytokine pleiotrophin as a driver of vascular abnormalization in glioma. Pleiotrophin abundance was greater in high-grade human astrocytomas and correlated with poor survival. Anaplastic lymphoma kinase (ALK), which is a receptor that is activated by pleiotrophin, was present in mural cells associated with abnormal vessels. Orthotopically implanted gliomas formed from GL261 cells that were engineered to produce pleiotrophin showed increased microvessel density and enhanced tumor growth compared with gliomas formed from control GL261 cells. The survival of mice with pleiotrophin-producing gliomas was shorter than that of mice with gliomas that did not produce pleiotrophin. Vessels in pleiotrophin-producing gliomas were poorly perfused and abnormal, a phenotype that was associated with increased deposition of vascular endothelial growth factor (VEGF) in direct proximity to the vasculature. The growth of pleiotrophin-producing GL261 gliomas was inhibited by treatment with the ALK inhibitor crizotinib, the ALK inhibitor ceritinib, or the VEGF receptor inhibitor cediranib, whereas control GL261 tumors did not respond to either inhibitor. Our findings link pleiotrophin abundance in gliomas with survival in humans and mice, and show that pleiotrophin promotes glioma progression through increased VEGF deposition and vascular abnormalization.

Serum pleiotrophin could be an early indicator for diagnosis and prognosis of non-small cell lung cancer

AIMS

Pleiotrophin (PTN), an angiogenic factor, is associated with various types of cancer, including lung cancer. Our aim was to investigate the possibility of using serum PTN as an early indicator regarding disease diagnosis, classification and prognosis, for patients with non-small cell lung cancer (NSCLC).

METHODS

Significant differences among PTN levels in patients with small cell lung cancer (SCLC, n=40), NSCLC (n=136), and control subjects with benign pulmonary lesions (n=21), as well as patients with different pathological subtypes of NSCLC were observed.

RESULTS

A serum level of PTN of 300.1 ng/ml, was determined as the cutoff value differentiating lung cancer patients and controls, with a sensitivity and specificity of 78.4% and 66.7%, respectively. Negative correlations between serum PTN level and pathological differentiation level, stage, and survival time were observed in our cohort of patients with NSCLC. In addition, specific elevation of PTN levels in pulmonary tissue in and around NSCLC lesions in comparison to normal pulmonary tissue obtained from the same subjects was also observed (n=2).

CONCLUSION

This study suggests that the serum PTN level of patients with NSCLC could be an early indicator for diagnosis and prognosis. This conclusion should be further assessed in randomized clinical trials.

Design of a platform technology for systemic delivery of siRNA to tumours using rolling circle transcription

For therapeutic applications of siRNA, there are technical challenges with respect to targeted and systemic delivery. We here report a new siRNA carrier, RNAtr NPs, in a way that multiple tandem copies of RNA hairpins as a result of rolling circle transcription (RCT) can be readily adapted in tumour-targeted and systemic siRNA delivery. RNAtr NPs provide a means of condensing large amounts of multimeric RNA transcripts into the compact nanoparticles, especially without the aid of polycationic agents, and thus reduce the risk of immunogenicity and cytotoxicity by avoiding the use of synthetic polycationic reagents. This strategy allows the design of a platform technology for systemic delivery of siRNA to tumour sites, because RCT reaction, which enzymatically generates RNA polymers in multiple copy numbers at low cost, can lead to directly accessible routes to targeted and systemic delivery. Therefore, RNAtr NPs suggest great potentials as the siRNA therapeutics for cancer treatment.

RNA interference has provided a promising tool to suppress the expression of specific genes associated with human diseases. Here, the authors present a platform technology for the systemic delivery of siRNA to tumour sites using rolling circle transcription.

Survivin small interfering RNA suppresses glioblastoma growth by inducing cellular apoptosis

A survivin small interfering RNA sequence specific for a human and mouse homogenous sequence was constructed. Survivin small interfering RNA could significantly inhibit glioma cell proliferation and induce apoptosis when it was transfected into either a human glioma cell line U251 or rat glioma C6 cells in vitro. In addition, treatment of rat orthotopic glioma models with survivin small interfering demonstrated the inhibition of glioma growth in vivo. Our experimental findings suggest that the use of RNA interference techniques to target the survivin sequence may be useful in the treatment of glioma.

TGF-β/Smad2/3 signal pathway involves in U251 cell proliferation and apoptosis

TGF-β/Smad2/3 signal pathway is regarded as a central regulator in various tumors, but its roles in brain cancer therapy remain unknown. In this study, we identify that the TGF-β/Smad2/3 signal pathway is activated in human brain glioma cells; inhibitor (SB203580) and siRNA against Smad2/3 quickly inhibited the phosphorylation of Smad2 and 3, expression of its major downstream gene, Ki-67, arrested cells in the G2/M phase and induced apoptosis of cells. The findings suggest that TGF-β/Smad2/3 pathway plays a key role in U251 cell growth and metastasis, which suggests its potential role in the molecular therapy of brain cancer.

RNA Interference Using c-Myc-Conjugated Nanoparticles Suppresses Breast and Colorectal Cancer Models

In this article, we report the development and preclinical validation of combinatorial therapy for treatment of cancers using RNA interference (RNAi). RNAi technology is an attractive approach to silence genes responsible for disease onset and progression. Currently, the critical challenge facing the clinical success of RNAi technology is in the difficulty of delivery of RNAi inducers, due to low transfection efficiency, difficulties of integration into host DNA and unstable expression. Using the macromolecule polyglycidal methacrylate (PGMA) as a platform to graft multiple polyethyleneimine (PEI) chains, we demonstrate effective delivery of small oligos (anti-miRs and mimics) and larger DNAs (encoding shRNAs) in a wide variety of cancer cell lines by successful silencing/activation of their respective target genes. Furthermore, the effectiveness of this therapy was validated for in vivo tumor suppression using two transgenic mouse models; first, tumor growth arrest and increased animal survival was seen in mice bearing Brca2/p53-mutant mammary tumors following daily intratumoral treatment with nanoparticles conjugated to c-Myc shRNA. Second, oral delivery of the conjugate to an Apc-deficient crypt progenitor colon cancer model increased animal survival and returned intestinal tissue to a non-wnt-deregulated state. This study demonstrates, through careful design of nonviral nanoparticles and appropriate selection of therapeutic gene targets, that RNAi technology can be made an affordable and amenable therapy for cancer.

Emerging therapies targeting intra-organ inflammation in transplantation

Over the past several years, the field of transplantation has witnessed significant progress on several fronts; in particular, achievements have been made in devising novel immunosuppressive strategies. An under-explored area that may hold great potential to improve transplantation outcomes is the design of novel strategies to apply specifically to organs to reduce intra-graft inflammation. A growing body of evidence indicates a key role of intra-graft inflammatory cascade in potently instigating the alloimmune response. Indeed, controlling the activation of innate immunity/inflammatory responses has been shown to be a promising strategy to increase the graft acceptance and survival. In this minireview, we provide an overview of emerging targeted strategies, which can be directly applied to grafts to down-regulate intra-graft inflammation prior to transplantation.

RETRACTED: Inhibition of PKM2 sensitizes triple-negative breast cancer cells to doxorubicin

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor and the author. We have been contacted by the corresponding author Yong Yang and by Houston Methodist Research Institute, who after investigation has concluded that the data of another researcher had been copied without authorization. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process.

Therapeutic potential of siRNA and DNAzymes in cancer

Cancer is characterized by uncontrolled cell growth, invasion, and metastasis and possess threat to humans worldwide. The scientific community is facing numerous challenges despite several efforts to cure cancer. Though a number of studies were done earlier, the molecular mechanism of cancer progression is not completely understood. Currently available treatments like surgery resection, adjuvant chemotherapy, and radiotherapy are not completely effective in curing all the cancers. Recent advances in the antisense technology provide a powerful tool to investigate various cancer pathways and target them. Small interfering RNAs (siRNAs) could be effective in downregulating the cancer-associated genes, but their in vivo delivery is the main obstacle. DNA enzymes (DNAzymes) have great potential in the treatment of cancer due to high selectivity and significant catalytic efficiency. In this review, we are focusing on antisense molecules such as siRNA and DNAzymes in cancer therapeutics development. This review also describes the challenges and approaches to overcome obstacles involved in using siRNA and DNAzymes in the treatment of cancers.

A novel nonviral gene delivery system: multifunctional envelope-type nano device

In this review we introduce a new concept for developing a nonviral gene delivery system which we call "Programmed Packaging." Based on this concept, we succeeded in developing a multifunctional envelope-type nano device (MEND), which exerts high transfection activities equivalent to those of an adenovirus in a dividing cell. The use of MEND has been extended to in vivo applications. PEG/peptide/DOPE ternary conjugate (PPD)-MEND, a new in vivo gene delivery system for the targeting of tumor cells that dissociates surface-modified PEG in tumor tissue by matrix metalloproteinase (MMP) and exerts significant transfection activities, was developed. In parallel with the development of MEND, a quantitative gene delivery system, Confocal Image-assisted 3-dimensionally integrated quantification (CIDIQ), also was developed. This method identified the rate-limiting step of the nonviral gene delivery system by comparing it with adenoviral-mediated gene delivery. The results of this analysis provide a new direction for the development of rational nonviral gene delivery systems.

Stimulating antitumor immunity with nanoparticles

A variety of strategies, have been applied to cancer treatment and the most recent one to become prominent is immunotherapy. This interest has been fostered by the demonstration that the immune system does recognize and often eliminate small tumors but tumors that become clinical problems block antitumor immune responses with immunosuppression orchestrated by the tumor cells. Methods to reverse this tumor-mediated immunosuppression will improve cancer immunotherapy outcomes. The immunostimulatory potential of nanoparticles (NPs), holds promise for cancer treatment. Phagocytes of various types are an important component of both immunosuppression and immunostimulation and phagocytes actively take up NPs of various sorts, so NPs are a natural system to manipulate these key immune regulatory cells. NPs can be engineered with multiple useful therapeutic features, such as various payloads such as antigens and/or immunomodulatory agents including cytokines, ligands for immunostimulatory receptors or antagonists for immunosuppressive receptors. As more is learned about how tumors suppress antitumor immune responses the payload options expand further. Here we review multiple approaches of NP-based cancer therapies to modify the tumor microenvironment and stimulate innate and adaptive immune systems to obtain effective antitumor immune responses.

Elevated expression of pleiotrophin in lymphocytic leukemia CD19+ B cells

Pleiotrophin (PTN) has been demonstrated to be strongly expressed in many fetal tissues, but seldom in healthy adult tissues. While PTN has been reported to be expressed in many types of tumors as well as at high serum concentrations in patients with many types of cancer, to date, there has been no report that PTN is expressed in leukemia, especially in lymphocytic leukemia. We isolated the CD19(+) subset of B cells from peripheral blood from healthy adults, B-cell acute lymphocytic leukemia (B-ALL) patients, and B-cell chronic lymphocytic leukemia (B-CLL) patients and examined these cells for PTN mRNA and protein expression. We used immunocytochemistry, western blotting, and enzyme-linked immunosorbent assay to show that PTN protein is highly expressed in CD19(+) B cells from B-ALL and B-CLL patients, but barely expressed in B cells from healthy adults. We also examined PTN expression at the nucleic acid level using reverse transcription polymerase chain reaction (RT-PCR) and northern blotting and detected a high levels of PTN transcripts in the CD19(+) B cells from both groups of leukemia patients, but very few in the CD19(+) B cells from the healthy controls. Interestingly, the quantity of the PTN transcripts correlated with the severity of disease. Moreover, suppression of PTN activity with an anti-PTN antibody promoted apoptosis of cells from leukemia patients and cell lines SMS-SB and JVM-2. This effect of the anti-PTN antibody suggests that PTN may be a new target for the treatment of lymphocytic leukemia.

Polymer-based delivery of RNA-based therapeutics in ovarian cancer

RNA interference (RNAi) is a naturally occurring, powerful mechanism for gene silencing, based on the cleavage of a given target mRNA. It relies on small interfering RNAs (siRNAs) in the cell. Being similar in structure, microRNAs (miRNAs) are important regulators of gene expression which mainly act by blocking mRNA translation. In cancer, certain miRNAs have been found to be pathologically downregulated. The therapeutic application of siRNAs or miRNAs for the induction of RNAi or miRNA replacement, respectively, relies on their efficient delivery through a non-viral formulation. Complexation of siRNAs/miRNAs in polymeric nanoparticles based on polyethylenimines (PEIs) offers protection against degradation, delivery to the target site, cellular uptake, and intracellular release. This chapter provides protocols for therapeutic gene silencing and miRNA replacement therapy, based on PEI complexes for in vitro and in vivo use.

ALK as a paradigm of oncogenic promiscuity: different mechanisms of activation and different fusion partners drive tumors of different lineages

Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase protein implicated in a variety of hematological malignancies and solid tumors. Since the identification of the ALK gene in 1994 as the target of the t(2;5) chromosomal translocation in anaplastic large cell lymphoma, ALK has been proven a remarkably promiscuous oncogene. ALK contributes to the development of a notable assortment of tumor types from different lineages, including hematolymphoid, mesenchymal, epithelial and neural tumors, through a variety of genetic mechanisms: gene fusions, activating point mutations, and gene amplification. Recent developments led to significant diagnostic and therapeutic advances, including efficient diagnostic tests and ALK-targeting agents readily available in the clinical setting. This review addresses some therapeutic considerations of ALK-targeted agents and the biologic implications of ALK oncogenic promiscuity, but the main points discussed are: 1) the variety of mechanisms that result in activation of the ALK oncogene, with emphasis on the promiscuous partnerships demonstrated in chromosomal rearrangements; 2) the diversity of tumor types of different lineages in which ALK has been implicated as a pathogenic driver; and 3) the different diagnostic tests available to identify ALK-driven tumors, and their respective indications.

T7 peptide-functionalized nanoparticles utilizing RNA interference for glioma dual targeting

Among all the malignant brain tumors, glioma is the deadliest and most common form with poor prognosis. Gene therapy is regarded as a promising way to halt the progress of the disease or even cure the tumor and RNA interference (RNAi) stands out. However, the existence of the blood-brain barrier (BBB) and blood tumor barrier (BTB) limits the delivery of these therapeutic genes. In this work, the delivery system targeting to the transferrin (Tf) receptor highly expressed on both BBB and glioma was successfully synthesized and would not compete with endogenous Tf. U87 cells stably express luciferase were employed here to simulate tumor and the RNAi experiments in vitro and in vivo validated that the gene silencing activity was 2.17-fold higher with the targeting ligand modification. The dual-targeting gene delivery system exhibits a series of advantages, such as high efficiency, low toxicity, stability and high transaction efficiency, which may provide new opportunities in RNAi therapeutics and nanomedicine of brain tumors.

Multi-compartmental oral delivery systems for nucleic acid therapy in the gastrointestinal tract

Gene and RNA interference therapies have significant potential for alleviating countless diseases, including many associated with the gastro-intestinal (GI) tract. Unfortunately, oral delivery of genes and small interfering RNA (siRNA) is very challenging due to the extracellular and intracellular barriers. In this review, we discuss the utilization of multi-compartmental delivery systems for oral administration of nucleic acid therapies. Some of the illustrative examples of multi-compartmental systems include solid nanoparticles-in-microsphere, solid nanoparticles-in-emulsion, and liquid nanoparticles-in-emulsion. Using type B gelatin nanoparticles encapsulated in poly(ε-caprolactone) microspheres, we have prepared nanoparticles-in-microsphere oral system (NiMOS) for gene and siRNA delivery for the treatment of inflammatory bowel disease (IBD). The results of these studies show that the multi-compartmental formulations can overcome many of the barriers for effective oral gene and siRNA delivery.