Potential clinical applications of siRNA technique: benefits and limitations

Functionalizing tetrahedral framework nucleic acids-based nanostructures for tumor in situ imaging and treatment

Timely in situ imaging and effective treatment are efficient strategies in improving the therapeutic effect and survival rate of tumor patients. In recent years, there has been rapid progress in the development of DNA nanomaterials for tumor in situ imaging and treatment, due to their unsurpassed structural stability, excellent material editability, excellent biocompatibility and individual endocytic pathway. Tetrahedral framework nucleic acids (tFNAs), are a typical example of DNA nanostructures demonstrating superior stability, biocompatibility, cell-entry performance, and flexible drug-loading ability. tFNAs have been shown to be effective in achieving timely tumor in situ imaging and precise treatment. Therefore, the progress in the fabrication, characterization, modification and cellular internalization pathway of tFNAs-based functional systems and their potential in tumor in situ imaging and treatment applications were systematically reviewed in this article. In addition, challenges and future prospects of tFNAs in tumor in situ imaging and treatment as well as potential clinical applications were discussed.

CRISPR-Cas9 potential for identifying novel therapeutic targets in muscle-invasive bladder cancer

Gene editing technologies help identify the genetic perturbations driving tumour initiation, growth, metastasis and resistance to therapeutics. This wealth of information highlights tumour complexity and is driving cancer research towards precision medicine approaches based on an individual's tumour genetics. Bladder cancer is the 11th most common cancer in the UK, with high rates of relapse and low survival rates in patients with muscle-invasive bladder cancer (MIBC). MIBC is highly heterogeneous and encompasses multiple molecular subtypes, each with different responses to therapeutics. This evidence highlights the need to identify innovative therapeutic targets to address the challenges posed by this heterogeneity. CRISPR-Cas9 technologies have been used to advance our understanding of MIBC and determine novel drug targets through the identification of drug resistance mechanisms, targetable cell-cycle regulators, and novel tumour suppressor and oncogenes. However, the use of these technologies in the clinic remains a substantial challenge and will require careful consideration of dosage, safety and ethics. CRISPR-Cas9 offers considerable potential for revolutionizing bladder cancer therapies, but substantial research is required for validation before these technologies can be used in the clinical setting.

Inactivity-induced phrenic motor facilitation requires PKCζ activity within phrenic motor neurons

Prolonged inhibition of respiratory neural activity elicits a long-lasting increase in phrenic nerve amplitude once respiratory neural activity is restored. Such long-lasting facilitation represents a form of respiratory motor plasticity known as inactivity-induced phrenic motor facilitation (iPMF). Although facilitation also occurs in inspiratory intercostal nerve activity after diminished respiratory neural activity (iIMF), it is of shorter duration. Atypical PKC activity in the cervical spinal cord is necessary for iPMF and iIMF, but the site and specific isoform of the relevant atypical PKC are unknown. Here, we used RNA interference to test the hypothesis that the zeta atypical PKC isoform (PKCζ) within phrenic motor neurons is necessary for iPMF but PKCζ within intercostal motor neurons is unnecessary for transient iIMF. Intrapleural injections of siRNAs targeting PKCζ (siPKCζ) to knock down PKCζ mRNA within phrenic and intercostal motor neurons were made in rats. Control rats received a nontargeting siRNA (NTsi) or an active siRNA pool targeting a novel PKC isoform, PKCθ (siPKCθ), which is required for other forms of respiratory motor plasticity. Phrenic nerve burst amplitude and external intercostal (T2) electromyographic (EMG) activity were measured in anesthetized and mechanically ventilated rats exposed to 30 min of respiratory neural inactivity (i.e., neural apnea) created by modest hypocapnia (20 min) or a similar recording duration without neural apnea (time control). Phrenic burst amplitude was increased in rats treated with NTsi (68 ± 10% baseline) and siPKCθ (57 ± 8% baseline) 60 min after neural apnea vs. time control rats (-3 ± 3% baseline), demonstrating iPMF. In contrast, intrapleural siPKCζ virtually abolished iPMF (5 ± 4% baseline). iIMF was transient in all groups exposed to neural apnea; however, intrapleural siPKCζ attenuated iIMF 5 min after neural apnea (50 ± 21% baseline) vs. NTsi (97 ± 22% baseline) and siPKCθ (103 ± 20% baseline). Neural inactivity elevated the phrenic, but not intercostal, responses to hypercapnia, an effect that was blocked by siPKCζ. We conclude that PKCζ within phrenic motor neurons is necessary for long-lasting iPMF, whereas intercostal motor neuron PKCζ contributes to, but is not necessary for, transient iIMF.NEW & NOTEWORTHY We report important new findings concerning the mechanisms regulating a form of spinal neuroplasticity elicited by prolonged inhibition of respiratory neural activity, inactivity-induced phrenic motor facilitation (iPMF). We demonstrate that the atypical PKC isoform PKCζ within phrenic motor neurons is necessary for long-lasting iPMF, whereas intercostal motor neuron PKCζ contributes to, but is not necessary for, transient inspiratory intercostal facilitation. Our findings are novel and advance our understanding of mechanisms contributing to phrenic motor plasticity.

Nanomaterials-Based Targeting of Long Non-Coding RNAs in Cancer: A Cutting-Edge Review of Current Trends

This review article spotlights the burgeoning potential of using nanotherapeutic strategies to target long non-coding RNAs (lncRNAs) in cancer cells. This updated discourse underlines the prominent role of lncRNAs in instigating cancer, facilitating its progression, and metastasis, validating lncRNAs' potential for being effective diagnostic biomarkers and therapeutic targets. The manuscript offers an in-depth examination of different strategies presently employed to modulate lncRNA expression and function for therapeutic purposes. Among these strategies, Antisense Oligonucleotides (ASOs), RNA interference (RNAi) technologies, and the innovative clustered regularly interspaced short palindromic repeats (CRISPR)-based gene editing tools garner noteworthy mention. A significant section of the review is dedicated to nanocarriers and their crucial role in drug delivery. These nanocarriers' efficiency in targeting lncRNAs in varied types of cancers is elaborated upon, validating the importance of targeted therapy. The manuscript culminates by reaffirming the promising prospects of targeting lncRNAs to enhance the accuracy of cancer diagnosis and improve treatment efficacy. Consequently, new paths are opened to more research and innovation in employing nanotherapeutic approaches against lncRNAs in cancer cells. Thus, this comprehensive manuscript serves as a valuable resource that underscores the vital role of lncRNAs and the various nano-strategies for targeting them in cancer treatment. Future research should also focus on unraveling the complex regulatory networks involving lncRNAs and identifying fundamental functional interactions to refine therapeutic strategies targeting lncRNAs in cancer.

Patient-Derived Exosomes as siRNA Carriers in Ovarian Cancer Treatment

RNA interference is a powerful gene-silencing tool with potential clinical applications. However, its therapeutic use is challenging because suitable carriers are unavailable. Exosomes are stable small endogenous vesicles that can transport functional molecules to target cells, making them ideal small interfering RNA (siRNA) carriers. Herein, we elucidated the therapeutic potential of patient-derived exosomes as an siRNA carrier for ovarian cancer (OC) treatment. The exosomes were extracted from the culture medium of primary fibroblasts collected from the omentum of patients with OC during surgery. MET proto-oncogene, receptor tyrosine kinase (MET) was selected for gene silencing, c-Met siRNAs were synthesized and loaded into the exosomes (Met-siExosomes) via electroporation, and the treatment effect of the Met-siExosomes was assessed in vitro and in vivo. The Met-siExosomes downregulated the c-Met protein levels and inhibited OC cell proliferation, migration, and invasion. In xenograft experiments using SKOV3-13 and ES-2 cells, Met-siExosomes were selectively extracted from peritoneally disseminated tumors. Intraperitoneal treatment suppressed the c-Met downstream targets in cancer cells and prolonged mouse survival. The synthesized siRNAs were successfully and selectively delivered via the exosomes to intraperitoneally disseminated tumors. As patients with OC routinely undergo omentectomy and abundant fibroblasts can be easily collected from the omentum, patient-derived exosomes may represent a promising therapeutic siRNA carrier to treat OC.

Small interfering RNA (siRNA)-based therapeutic applications against viruses: principles, potential, and challenges

RNA has emerged as a revolutionary and important tool in the battle against emerging infectious diseases, with roles extending beyond its applications in vaccines, in which it is used in the response to the COVID-19 pandemic. Since their development in the 1990s, RNA interference (RNAi) therapeutics have demonstrated potential in reducing the expression of disease-associated genes. Nucleic acid-based therapeutics, including RNAi therapies, that degrade viral genomes and rapidly adapt to viral mutations, have emerged as alternative treatments. RNAi is a robust technique frequently employed to selectively suppress gene expression in a sequence-specific manner. The swift adaptability of nucleic acid-based therapeutics such as RNAi therapies endows them with a significant advantage over other antiviral medications. For example, small interfering RNAs (siRNAs) are produced on the basis of sequence complementarity to target and degrade viral RNA, a novel approach to combat viral infections. The precision of siRNAs in targeting and degrading viral RNA has led to the development of siRNA-based treatments for diverse diseases. However, despite the promising therapeutic benefits of siRNAs, several problems, including impaired long-term protein expression, siRNA instability, off-target effects, immunological responses, and drug resistance, have been considerable obstacles to the use of siRNA-based antiviral therapies. This review provides an encompassing summary of the siRNA-based therapeutic approaches against viruses while also addressing the obstacles that need to be overcome for their effective application. Furthermore, we present potential solutions to mitigate major challenges.

Small interference (RNAi) technique: Exploring its clinical applications, benefits and limitations

BACKGROUND

Small interference RNA (siRNA) has emerged as the most desired method for researchers and clinicians who wish to silence a specific gene of interest and has been extensively developed as a therapeutic agent. This review points to collecting all clinical trials on siRNA and understanding its benefits, pharmacokinetics and safety by reading articles published in the last 5 years.

MATERIALS AND METHODS

Searching in the PubMed database using 'siRNA' and 'in vivo' with limits to articles published in the previous 5 years, article type 'clinical trials' and language 'English' to acquire papers on in vivo studies on siRNA approaches. Features of siRNA clinical trials registered at https://clinicaltrials.gov/ were analysed.

RESULTS

So far, 55 clinical studies have been published on siRNA. Many published clinical trials on siRNA showed tolerability, safety and effectiveness in treating cancers like breast, lung, colon, and other organs and other diseases like viral infections and hereditary diseases. Many different routes of administration can silence many genes at the same time. Limitations and uncertainties associated with siRNA treatment include the effectiveness of cellular uptake, precise targeting of the intended tissue or cell and prompt elimination from the body.

CONCLUSIONS

The siRNA or RNAi method will be one of the most critical and influential techniques to fight against many different diseases. Although the RNAi approach has certain advantages, it also has limitations concerning clinical applications. Overcoming these limitations remains a daunting challenge.

siRNA-Based Novel Therapeutic Strategies to Improve Effectiveness of Antivirals: An Insight

Since the ground-breaking discovery of RNA interference (RNAi), scientists have made significant progress in the field of small interfering RNA (siRNA) treatments. Due to severe barriers to the therapeutic application of siRNA, nanoparticle technologies for siRNA delivery have been designed. For pathological circumstances such as viral infection, toxic RNA abnormalities, malignancies, and hereditary diseases, siRNAs are potential therapeutic agents. However, systemic administration of siRNAs in vivo remains a substantial issue due to a lack of "drug-likeness" (siRNA are relatively larger than drugs and have low hydrophobicity), physiological obstacles, and possible toxicities. This write-up covers important accomplishment in the field of clinical trials and patents specially based of siRNAs using targeting viruses. Furthermore, it offers deep insight of nanoparticle applied for siRNA delivery and strategies to improve the effectiveness of antivirals.

Emergence of Nanoscale Drug Carriers through Supramolecular Self-Assembly of RNA with Calixarene

Supramolecular self-assembly is a powerful tool for the development of polymolecular assemblies that can form the basis of useful nanomaterials. Given the increasing popularity of RNA therapy, the extension of this concept of self-assembly to RNA is limited. Herein, a simple method for the creation of nanosized particles through the supramolecular self-assembly of RNA with a three-dimensional macrocycle from the calixarene family was reported for the first time. This self-assembly into nanoparticles was realized using cooperative supramolecular interactions under mild conditions. The obtained nanoparticles are able to bind various hydrophobic (quercetin, oleic acid) and hydrophilic (doxorubicin) drugs, as a result of which their cytotoxic properties are enhanced. This work demonstrates that intermolecular interactions between flexible RNA and rigid calixarene is a promising route to bottom-up assembly of novel supramolecular soft matter, expanding the design possibilities of nanoscale drug carriers.

Effects of Different Lengths of a Nucleic Acid Binding Region and Bound Nucleic Acids on the Phase Behavior and Purification Process of HBcAg Virus-Like Particles

Virus-like particles (VLPs) are macromolecular structures with great potential as vehicles for the targeted administration of functional molecules. Loaded with nucleic acids, VLPs are a promising approach for nanocarriers needed for gene therapy. There is broad knowledge of the manufacturing of the truncated wild-type lacking a nucleic acid binding region, which is mainly being investigated for vaccine applications. Whereas for their potential application as a nanocarrier for gene therapy, hepatitis B core antigen (HBcAg) VLPs with a nucleic acid binding region for efficient cargo-loading are being investigated. VLP structure, loading, and phase behavior are of central importance to their therapeutic efficacy and thereby considerably affecting the production process. Therefore, HBcAg VLPs with different lengths of the nucleic acid binding region were produced in E. coli. VLP attributes such as size, zeta potential, and loading with host cell-derived nucleic acids were evaluated. Capsid’s size and zeta potential of the VLP constructs did not differ remarkably, whereas the analysis of the loading with host cell-derived nucleic acids revealed strong differences in the binding of host cell-derived nucleic acids dependent on the length of the binding region of the constructs, with a non-linear correlation but a two-zone behavior. Moreover, the phase behavior and purification process of the HBcAg VLPs as a function of the liquid phase conditions and the presence of host cell-derived nucleic acids were investigated. Selective VLP precipitation using ammonium sulfate was scarcely affected by the encapsulated nucleic acids. However, the disassembly reaction, which is crucial for structure homogeneity, separation of encapsulated impurities, and effective loading of the VLPs with therapeutic nucleic acids, was affected both by the studied liquid phase conditions, varying pH and concentration of reducing agents, and the different VLP constructs and amount of bound nucleic acids, respectively. Thereby, capsid-stabilizing effects of the bound nucleic acids and capsid-destabilizing effects of the nucleic acid binding region were observed, following the two-zone behavior of the construct’s loading, and a resulting correlation between the capsid stability and disassembly yields could be derived.

Simultaneous quantification of oligo-nucleic acids and a ferritin nanocage by size-exclusion chromatography hyphenated to inductively coupled plasma mass spectrometry for developing drug delivery systems

An analytical methodology, which can quantify nucleic acids, ferritin nanocages, and their complexes in a single injection, was established by means of size-exclusion chromatography hyphenated with inductively coupled plasma mass spectrometry (SEC-ICP-MS). In this study, several oligo-nucleic acids and ferritin (a human-derived cage-shaped protein) were used as model compounds of nucleic acid drugs (NAD) and drug delivery system (DDS) carriers, respectively. A fraction based on the nucleic acid-ferritin complex was completely distinguished from one based on free nucleic acids by SEC separation. The nucleic acids and ferritin were quantified based on the number of phosphorus and sulfur atoms, respectively. The quantification was carried out by an external calibration method using a series of elemental standard solutions without preparing designated standard materials for each drug candidate. The analytical performance, including sensitivity and accuracy, was evaluated to be appropriate for evaluating the medicines already launched in the market. As demonstrated in the latter part of this study, the encapsulation mechanism is possibly regulated by not only the averaged molecular size of nucleic acids but also the surface charge related to the number of (deoxy-) ribonucleotides. We believe that the methodology presented in this study has the potential to accelerate the development of new modalities based on NAD-DDS to realize therapies in the future.

Novel molecular approaches to combat vectors and vector-borne viruses: Special focus on RNA interference (RNAi) mechanisms

Vector-borne diseases, such as dengue, chikungunya, zika, yellow fever etc pose significant burden among the infectious diseases globally, especially in tropical and sub-tropical regions. Globalization, deforestation, urbanization, climate change, uncontrolled population growth, inadequate waste management and poor vector-management infrastructure have all contributed to the expansion of vector habitats and subsequent increase in vector-borne diseases throughout the world. Conventional vector control methods, such as use of insecticides, have significant negative environmental repercussions in addition to developing resistance in vectors. Till date, a very few vaccines or antiviral therapies have been approved for the treatment of vector borne diseases. In this review, we have discussed emerging molecular approaches like CRISPR (clustered regularly interspaced short palindromic repeats)/Cas-9, sterile insect technique (SIT), release of insects carrying a dominant lethal (RIDL), Wolbachia (virus transmission blocking) and RNA interference (RNAi) to combat vector and vector-borne viruses. Due to the extensive advancements in RNAi research, a special focus has been given on its types, biogenesis, mechanism of action, delivery and experimental studies evaluating their application as anti-mosquito and anti-viral agent. These technologies appear to be highly promising in terms of contributing to vector control and antiviral drug development, and hence can be used to reduce global vector and vector-borne disease burden.

Modulation of Macrophage Response by Copper and Magnesium Ions in Combination with Low Concentrations of Dexamethasone

Macrophages have been deemed crucial for correct tissue regeneration, which is a complex process with multiple overlapping phases, including inflammation. Previous studies have suggested that divalent ions are promising cues that can induce an anti-inflammatory response, since they are stable cues that can be released from biomaterials. However, their immunomodulatory potential is limited in a pro-inflammatory environment. Therefore, we investigated whether copper and magnesium ions combined with low concentrations of the anti-inflammatory drug, dexamethasone (dex), could have a synergistic effect in macrophage, with or without pro-inflammatory stimulus, in terms of morphology, metabolic activity and gene expression. Our results showed that the combination of copper and dex strongly decreased the expression of pro-inflammatory markers, while the combination with magnesium upregulated the expression of IL-10. Moreover, in the presence of a pro-inflammatory stimulus, the combination of copper and dex induced a strong TNF-α response, suggesting an impairment of the anti-inflammatory actions of dex. The combination of magnesium and dex in the presence of a pro-inflammatory stimulus did not promote any improvement in comparison to dex alone. The results obtained in this study could be relevant for tissue engineering applications and in the design of platforms with a dual release of divalent ions and small molecules.

Albumin-Binding Aptamer Chimeras for Improved siRNA Bioavailability

Introduction

Short interfering RNAs (siRNAs) are potent nucleic acid-based drugs designed to target disease driving genes that may otherwise be undruggable with small molecules. However, therapeutic potential of siRNA in vivo is limited by poor pharmacokinetic properties, including rapid renal clearance and nuclease degradation. Backpacking on natural carriers such as albumin, which is present at high concentration and has a long half-life in serum, is an effective way to modify pharmacokinetics of biologic drugs that otherwise have poor bioavailability. In this work, we sought to develop albumin-binding aptamer-siRNA chimeras to improve the bioavailability of siRNA.

Methods

A Systematic Evolution of Ligands through Exponential Enrichment (SELEX) approach was used to obtain modified RNA-binding aptamers, which were then fused directly to siRNA via in vitro transcription. Molecular and pharmacokinetic properties of the aptamer-siRNA chimeras were subsequently measured in vitro and in vivo.

Results

In vitro assays show that albumin-binding aptamers are stable in serum while maintaining potent gene knockdown capabilities in the chimera format. In vivo, the absolute circulation half-life of the best-performing aptamer-siRNA chimera (Clone 1) was 1.6-fold higher than a scrambled aptamer chimera control.

Conclusions

Aptamer-siRNA chimeras exhibit improved bioavailability without compromising biological activity. Hence, this albumin-binding aptamer-siRNA chimera approach may be a promising strategy for drug delivery applications.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-022-00718-y.

New paradigm in combination therapy of siRNA with chemotherapeutic drugs for effective cancer therapy

Chemotherapeutics drugs play a pivotal role in the treatment of cancer. However, many issues generate by chemotherapy drugs, including unfavorable harm to healthy cells and multidrug resistance (MDR), persist and have a negative impact on therapeutic outcomes. When compared to monotherapy, combination cancer therapy has many advantages, like improving efficacy through synergistic effects and overcoming drug resistance. Combination treatment may comprise several chemotherapeutics drugs and combinations of chemotherapeutic drugs with some other therapeutic options such as surgery or radiation. Cancer treatment that utilizes co-delivery strategies with siRNA and chemotherapeutic drugs has been shown to have highly effective antitumor effects in the treatment of many cancers. However, the highly complex mechanisms of chemotherapeutic drugs-siRNA pairs during the co-delivery process have received little attention. The ideal combination of chemotherapeutic drugs with siRNA is very crucial for producing the desirable anticancer effects that would greatly enhance therapeutic efficiency. This review puts an emphasis on the logic for choosing suitable chemotherapeutic drug-siRNA combinations, which may open the way for the co-delivery of chemotherapeutic drugs and siRNA for treating cancer in the clinic. This review summarizes recent breakthrough in the area of diverse mechanism-based chemotherapeutic drugs-siRNA combinations in cancer treatment.

Serine-Threonine Kinase Receptor-Associated Protein (STRAP) Knockout Decreases the Malignant Phenotype in Neuroblastoma Cell Lines

Background: Serine-threonine kinase receptor-associated protein (STRAP) plays an important role in neural development but also in tumor growth. Neuroblastoma, a tumor of neural crest origin, is the most common extracranial solid malignancy of childhood and it continues to carry a poor prognosis. The recent discovery of the role of STRAP in another pediatric solid tumor, osteosarcoma, and the known function of STRAP in neural development, led us to investigate the role of STRAP in neuroblastoma tumorigenesis. Methods: STRAP protein expression was abrogated in two human neuroblastoma cell lines, SK-N-AS and SK-N-BE(2), using transient knockdown with siRNA, stable knockdown with shRNA lentiviral transfection, and CRISPR-Cas9 genetic knockout. STRAP knockdown and knockout cells were examined for phenotypic alterations in vitro and tumor growth in vivo. Results: Cell proliferation, motility, and growth were significantly decreased in STRAP knockout compared to wild-type cells. Indicators of stemness, including mRNA abundance of common stem cell markers Oct4, Nanog, and Nestin, the percentage of cells expressing CD133 on their surface, and the ability to form tumorspheres were significantly decreased in the STRAP KO cells. In vivo, STRAP knockout cells formed tumors less readily than wild-type tumor cells. Conclusion: These novel findings demonstrated that STRAP plays a role in tumorigenesis and maintenance of neuroblastoma stemness.

Determining the Biological Mechanisms of Action for Environmental Exposures: Applying CRISPR/Cas9 to Toxicological Assessments

Toxicology is a constantly evolving field, especially in the area of developing alternatives to animal testing. Toxicological research must evolve and utilize adaptive technologies in an effort to improve public, environmental, and occupational health. The most commonly cited mechanisms of toxic action after exposure to a chemical or particle test substance is oxidative stress. However, because oxidative stress involves a plethora of genes and proteins, the exact mechanism(s) are not commonly defined. Exact mechanisms of toxicity can be revealed using an emerging laboratory technique referred to as CRISPR (clustered regularly interspaced short palindromic repeats). This article reviews the most common CRISPR techniques utilized today and how each may be applied in Toxicological Sciences. Specifically, the CRISPR/CRISPR-associated protein complex is used for single gene knock-outs, whereas CRISPR interference/activation is used for silencing or activating (respectively) ribonucleic acid. Finally, CRISPR libraries are used for knocking-out entire gene pathways. This review highlights the application of CRISPR in toxicology to elucidate the exact mechanism through which toxicants perturb normal cellular functions.

Epigenetic regulation of angiogenesis in lung cancer

Lung cancer is the leading cause of cancer-related deaths worldwide, in which angiogenesis is highly required for lung cancer cell growth and metastasis. Genetic regulation of this multistep process is being studied extensively, however, relatively less is known about the epigenetic regulation of angiogenesis in lung cancer. Several epigenetic alterations contribute to regulating angiogenesis, such as epimodifications of DNA, posttranslational modification of histones, and expression of noncoding RNAs. Here, we review the current knowledge of the epigenetic regulation of angiogenesis and discuss the potential clinical applications of epigenetic-based anticancer therapy in lung cancer. Overall, epigenetic-based therapy will likely emerge as a prominent approach to treat lung cancer in the future.

The importance of co-delivery of nanoparticle-siRNA and anticancer agents in cancer therapy

According to global statistics, cancer is the second leading cause of death worldwide. Because of the heterogeneity of cancer, single-drug therapy has many limitations due to low efficacy. Therefore, combination therapy with two or more therapeutic agents is being arisen. One of the most important approaches in cancer therapy is the shot down of key genes involved in apoptotic processes and cell cycle. In this regard, siRNA is a good candidate, a highly attractive method to suppressing tumor growth and invasion. Combination therapy with siRNAs and chemotherapeutic agents can overcome the multidrug resistance and increase apoptosis. The efficient delivery of siRNA to the target cell/tissue/organ has been a challenge. To overcome these challenges, the presence of suitable delivery systems by using nanoparticles is interesting. In this review, we discuss the current challenges for successful RNA interference. Also, we suggested proper a strategy for delivering siRNA that can be useful in targeting therapy. Finally, the combination of a variety of anticancer drugs and siRNA through acceptable delivery systems and their effects on cell cycle and apoptosis will be evaluated.

Folate Receptor-Mediated siRNA Delivery: Recent Developments and Future Directions for RNAi Therapeutics

RNA interference (RNAi), a gene regulatory process mediated by small interfering RNAs (siRNAs), has made remarkable progress as a potential therapeutic agent against various diseases. However, RNAi is associated with fundamental challenges such as poor systemic delivery and susceptibility to the nucleases. Targeting ligand-bound delivery vehicles has improved the accumulation of drug at the target site, which has resulted in high transfection efficiency and enhanced gene silencing. Recently, folate receptor (FR)-mediated targeted delivery of siRNAs has garnered attention due to their enhanced cellular uptake and high transfection efficiency toward tumor cells. Folic acid (FA), due to its small size, low immunogenicity, high in vivo stability, and high binding affinity toward FRs, has attracted much attention for targeted siRNA delivery. FRs are overexpressed in a large number of tumors, including ovarian, breast, kidney, and lung cancer cells. In this review, we discuss recent advances in FA-mediated siRNA delivery to treat cancers and inflammatory diseases. This review summarizes various FA-conjugated nanoparticle systems reported so far in the literature, including liposome, silica, metal, graphene, dendrimers, chitosan, organic copolymers, and RNA nanoparticles. This review will help in the design and development of potential delivery vehicles for siRNA drug targeting to tumor cells using an FR-mediated approach.

Tetrahedral Framework Nucleic Acids Loaded with Aptamer AS1411 for siRNA Delivery and Gene Silencing in Malignant Melanoma

siRNA is found to effectively knock down the target gene in cells, which is considered a promising strategy for gene therapy. However, the application of siRNA is limited due to its low efficiency of the cellular uptake. Tetrahedral framework nucleic acids (tFNAs) are synthesized by four single-stranded DNAs and show multiple biological functions in recent studies, especially suitable for drug delivery. More than 60% of malignant melanomas are associated with Braf gene mutation, an attractive therapeutic target for RNA interference. In this study, we modified anti-Braf siRNA (siBraf) with tFNAs to downregulate the target gene. Meanwhile, we directly incorporated AS1411 (a DNA aptamer) to our nanostructure, which assists tFNAs to improve the cellular uptake efficacy of siBraf significantly. The results indicated that tFNAs-AS1411-siBraf exhibited more potent activity to cleave Braf mRNA than free siBraf. This study may provide a new idea for the combination therapy of siRNA and aptamers via DNA nanomaterials to achieve gene silencing.

Novel use of a chemically modified siRNA for robust and sustainable in vivo gene silencing in the retina

Despite efficient and specific in vitro knockdown, more reliable and convenient methods for in vivo knockdown of target genes remain to be developed particularly for retinal research. Using commercially available and chemically modified siRNA so-called Accell siRNA, we established a novel in vivo gene silencing approach in the rat retina. siRNA designed for knockdown of the house keeping gene Gapdh or four retinal cell type-specific genes (Nefl, Pvalb, Rho and Opn1sw) was injected into the vitreous body, and their retinal mRNA levels were quantified using real-time PCR. Intravitreal injection of siRNA for Gapdh resulted in approximately 40–70% reduction in its retinal mRNA levels, which lasted throughout a 9-day study period. Furthermore, all the selected retinal specific genes were efficiently down-regulated by 60–90% following intravitreal injection, suggesting injected siRNA penetrated into major retinal cell types. These findings were consistent with uniform distribution of a fluorescence-labeled siRNA injected into the vitreous body. Interestingly, gene silencing of Grin1, a core subunit of NMDA receptor, was accompanied by significant prevention from NMDA-induced retinal ganglion cell death. Thus, we provide single intravitreal injection of Accell siRNA as a versatile technique for robust and sustainable in vivo retinal gene silencing to characterize their biological functions under physiological and pathophysiological conditions.

Serum Metabolomics Associating With Circulating MicroRNA Profiles Reveal the Role of miR-383-5p in Rat Hippocampus Under Simulated Microgravity

Microgravity impacts various aspects of human health. Yet the mechanisms of spaceflight-induced health problems are not elucidated. Here, we mapped the fusion systemic analysis of the serum metabolome and the circulating microRNAome in a hindlimb unloading rat model to simulate microgravity. The response of serum metabolites and microRNAs to simulated microgravity was striking. Integrated pathway analysis of altered serum metabolites and target genes of the significantly altered circulating miRNAs with Integrated Molecular Pathway-Level Analysis (IMPaLA) software was mainly suggestive of modulation of neurofunctional signaling pathways. Particularly, we revealed significantly increased miR-383-5p and decreased aquaporin 4 (AQP4) in the hippocampus. Using rabies virus glycoprotein-modified exosomes, delivery of miR-383-5p inhibited the expression of AQP4 not only in rat C6 glioma cells in vitro but also in the hippocampus in vivo. Using bioinformatics to map the crosstalk between the circulating metabolome and miRNAome could offer opportunities to understand complex biological systems under microgravity. Our present results suggested that the change of miR-383-5p level and its regulation of target gene AQP4 was one of the potential molecular mechanisms of microgravity-induced cognitive impairment in the hippocampus.

EpCAM-Targeted 3WJ RNA Nanoparticle Harboring Delta-5-Desaturase siRNA Inhibited Lung Tumor Formation via DGLA Peroxidation

Knocking down delta-5-desaturase (D5D) expression by D5D small interfering RNA (siRNA) has been reported that could redirect the cyclooxygenase-2 (COX-2)-catalyzed dihomo-γ-linolenic acid (DGLA) peroxidation from producing prostaglandin E2 to 8-hydroxyoctanoic acid (8-HOA), resulting in the inhibition of colon and pancreatic cancers. However, the effect of D5D siRNA on lung cancer is still unknown. In this study, by incorporating epithelial cell adhesion molecule (EpCAM) aptamer and validated D5D siRNA into the innovative three-way junction (3WJ) RNA nanoparticle, target-specific accumulation and D5D knockdown were achieved in the lung cancer cell and mouse models. By promoting the 8-HOA formation from the COX-2-catalyzed DGLA peroxidation, the 3WJ-EpCAM-D5D siRNA nanoparticle inhibited lung cancer growth in vivo and in vitro. As a potential histone deacetylases inhibitor, 8-HOA subsequently inhibited cancer proliferation and induced apoptosis via suppressing YAP1/TAZ nuclear translocation and expression. Therefore, this 3WJ-RNA nanoparticle could improve the targeting and effectiveness of D5D siRNA in lung cancer therapy.

Reduction sensitive nanocarriers mPEG-g-γ-PGA/SSBPEI@siRNA for effective targeted delivery of survivin siRNA against NSCLC

Poly γ-glutamic acid (γ-PGA) is attractive due to its desirable biological properties such as nontoxicity, excellent biocompatibility, and minimal immunogenicity. Additionally, γ-PGA could be recognized by γ-glutamyl transpeptidase, which is regarded as a potential biomarker for many tumors. In this study, we have developed a new biodegradable, reduction sensitive, and tumor-specific gene nano-delivery platform consisting of a cationic carrier (SSBPEI) for siRNA condensation, mPEG shell for nanoparticle stabilization, and γ-PGA for accelerated cellular uptake. Disulfide bonds (-SS-) could be reduced specifically in the tumor environment, which is full of reductants such as glutathione reductase. Conjugating polyethylene glycol (PEG) to the γ-PGA led to the formation of mPEG-g-γ-PGA, with a decreased positive charge on the surface of SSBPEI@siRNA and substantially higher stability in an aqueous medium. As a result, mPEG-g-γ-PGA/SSBPEI@siRNA nanoparticles could protect siRNAs from RNase A degradation and release siRNAs in a reduction sensitive way. The multifunctional delivery system was shown to silence the Survivin gene and further promote chemotherapeutic drug-induced apoptosis in the A549 NSCLC cell line efficiently, thereby representing a novel promising platform for the delivery of siRNAs.

Lipoprotein-Like Nanoparticle Carrying Small Interfering RNA Against Spalt-Like Transcription Factor 4 Effectively Targets Hepatocellular Carcinoma Cells and Decreases Tumor Burden

Patients with advanced hepatocellular carcinoma (HCC) are often unable to tolerate chemotherapy due to liver dysfunction in the setting of cirrhosis. We investigate high-density lipoprotein (HDL)-mimicking peptide phospholipid scaffold (HPPS), which are nanoparticles that capitalize on normal lipoprotein metabolism and transport, as a solution for directed delivery of small interfering RNA (siRNA) cargo into HCC cells. Spalt-like transcription factor 4 (SALL4), a fetal oncoprotein expressed in aggressive HCCs, is specifically targeted as a case study to evaluate the efficacy of HPPS carrying siRNA cargo. HPPS containing different formulations of siRNA therapy against SALL4 were generated specifically for HCC cells. These were investigated both in vitro and in vivo using fluorescence imaging. HPPS-SALL4 effectively bound to scavenger receptor, class B type 1 (SR-BI) and delivered the siRNA cargo into HCC cells, as seen in vitro. HPPS-SALL4 effectively inhibited HCC tumor growth (P < 0.05) and induced a 3-fold increase in apoptosis of the cancer cells in vivo compared to HPPS-scramble. Additionally, there was no immunogenicity associated with HPPS-SALL4 as measured by cytokine production. Conclusion: We have developed unique HDL-like nanoparticles that directly deliver RNA interference (RNAi) therapy against SALL4 into the cytosol of HCC cells, effectively inhibiting HCC tumor growth without any systemic immunogenicity. This therapeutic modality avoids the need for hepatic metabolism in this cancer, which develops in the setting of cirrhosis and liver dysfunction. These natural lipoprotein-like nanoparticles with RNAi therapy are a promising therapeutic strategy for HCC.

Advances in covalent kinase inhibitors

This comprehensive review details recent advances, challenges and innovations in covalent kinase inhibition within a 10 year period (2007–2018).

siRNA nanotherapeutics: a promising strategy for anti‐HBV therapy

Chronic hepatitis B (CHB) is the most common cause of hepatocellular carcinoma (HCC) and liver cirrhosis worldwide. In spite of the numerous advances in the treatment of CHB, drugs and vaccines have failed because of many factors like complexity, resistance, toxicity, and heavy cost. New RNA interference (RNAi)‐based technologies have developed innovative strategies to target Achilles' heel of the several hazardous diseases involving cancer, some genetic disease, autoimmune illnesses, and viral disorders particularly hepatitis B virus (HBV) infections. Naked siRNA delivery has serious challenges including failure to cross the cell membrane, susceptibility to the enzymatic digestion, and excretion by renal filtration, which ideally can be addressed by nanoparticle‐mediated delivery systems. cccDNA formation is a significant problem in obtaining HBV infections complete cure because of strength, durability, and lack of proper immune response. Nano‐siRNA drugs have a great potential to address this problem by silencing specific genes which are involved in cccDNA formation. In this article, the authors describe siRNA nanocarrier‐mediated delivery systems as a promising new strategy for HBV infections therapy. Simultaneously, the authors completely represent the clinical trials which use these strategies for treatment of the HBV infections.

DNA tetrahedron-based nanogels for siRNA delivery and gene silencing

DNA tetrahedra are employed as building blocks to construct a novel DNA-based nanogel for intracellular siRNA delivery.

A review on current status of antiviral siRNA

Viral diseases like influenza, AIDS, hepatitis, and Ebola cause severe epidemics worldwide. Along with their resistant strains, new pathogenic viruses continue to be discovered so creating an ongoing need for new antiviral treatments. RNA interference is a cellular gene‐silencing phenomenon in which sequence‐specific degradation of target mRNA is achieved by means of complementary short interfering RNA (siRNA) molecules. Short interfering RNA technology affords a potential tractable strategy to combat viral pathogenesis because siRNAs are specific, easy to design, and can be directed against multiple strains of a virus by targeting their conserved gene regions. In this review, we briefly summarize the current status of siRNA therapy for representative examples from different virus families. In addition, other aspects like their design, delivery, medical significance, bioinformatics resources, and limitations are also discussed.

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 iron nanoparticles with platinum-(IV) prodrugs and anti-EZH2 siRNA show great synergy in combating drug resistance in vitro and in vivo

Resistance to platinum agents is challenging in cancer treatment with platinum drugs. Such resistant cells prevent effective platinum accumulation intracellular and alter cellular adaptations to survive from cytotoxicity by regulating corresponding proteins expression. Ideal therapeutics should combine resolution to these pump and non-pump relevant resistance of cancer cells to achieve high efficacy and low side effect. Fe₃O₄ nanocarrier loaded with drugs could enter cells in a more efficient endocytosis manner which circumvents pump-relevant drug resistance. EZH2 protein which was previously found to be over-expressed in drug-resistant cancer cells was reported to be involved in platinum drug resistance and play a vital role in anti-apoptosis pathways. Here, we report Fe₃O₄ nanoparticles loaded with siEZH2 (siRNA), a platinum prodrug in +4 oxidation state (cis, cis, trans-diamminedichlorodisuccinato-platinum-(IV), namely Pt(IV)) and luteinizing hormone-releasing hormone (LHRH) targeting polypeptides. Results show that targeted nanoparticles loading with siEZH2 synergize with Pt(IV) and result in similar cell killing performance to A2780/DDP cells (cisplatin resistant) compared with non-siEZH2 loaded nanoparticles to A2780 cells (cisplatin sensitive). Thus, this Fe₃O₄@PEI-Pt(IV)-PEG-LHRH@siEZH2 nanoparticles reverse the cisplatin resistance from the pump and non-pump relevant aspects, fully taking advantage of nanocarrier system.

Recent advances in TPGS-based nanoparticles of docetaxel for improved chemotherapy

Docetaxel (DTX) is one of the important antitumor drugs, being used in several common chemotherapies to control leading cancer types. Severe toxicities of the DTX are prominent due to sudden parenteral exposure of desired loading dose to maintain the therapeutic concentration. Field of nanotechnology is leading to resist sudden systemic exposure of DTX with more specific delivery to the site of cancer. Further nanometric size range of the formulation aid for prolonged circulation, thereby extensive exposure results better efficacy. In this article, we extensively reviewed the therapeutic benefit of incorporating d-α-tocopheryl polyethylene glycol 1000 succinate (vitamin E TPGS, or simply TPGS) in the nanoparticle (NP) formulation of DTX for improved delivery, tumor control and tolerability. TPGS is well accepted nonionic-ampiphilic polymer which has been identified in the role of emulsifier, stabilizer, penetration enhancer, solubilizer and in protection in micelle. Simultaneously, P-glycoprotein inhibitory activity of TPGS in the multidrug resistant (MDR) cancer cells along with its apoptotic potential are the added advantage of TPGS to be incorporated in nano-chemotherapeutics. Thus, it could be concluded that TPGS based nanoparticulate application is an advanced approach to improve therapeutic efficacy of chemotherapeutic agents by better internalization and sustained retention of the NPs.

Novel benzopyran derivatives and their therapeutic applications: a patent review (2009-2016)

INTRODUCTION

The benzopyran derivatives present a wide variety of biological activity and behaviour. At the same time the benzopyran derivatives support their use as therapeutic agents for multiple diseases. Their structural characteristics correlated to physicochemical properties seem to define the extent of the biological activity. Areas covered: This review summarizes new patents published on new benzopyran derivatives from 2009 to 2016. Expert opinion: Many benzopyran derivatives have vivo/vitro biological responses. Their clinical evaluation will be critical to assess therapeutic utility. The compounds containing benzopyran moiety is well defined as lead compounds for design of new more promising molecules.

Fabrication of hydroxyapatite/chitosan composite hydrogels loaded with exosomes derived from miR-126-3p overexpressed synovial mesenchymal stem cells for diabetic chronic wound healing

The exploration of an effective diabetic chronic wound healing process still remains a great challenge. Herein, we used gene overexpression technology to obtain synovial mesenchymal stem cells (SMSCs) and the miR-126-3p highly expressed SMSCs (SMSCs-126). The exosomes derived from miR-126-3p overexpressed SMSCs (SMSCs-126-Exos) with a particle size of 85 nm were encapsulated in hydroxyapatite/chitosan (HAP-CS) composite hydrogels (HAP-CS-SMSCs-126-Exos) as wound dressings. The SMSCs-126-Exos, CS and low-crystallinity HAP nanorods with a length of 200 nm and a diameter of 50 nm are uniformly dispersed within the whole composite hydrogel. The HAP-CS-SMSCs-126-Exos possess the controlled release property of SMSCs-126-Exos for at least 6 days. The released SMSCs-126-Exos nanoparticles stimulate the proliferation and migration of human dermal fibroblasts and human dermal microvascular endothelial cells (HMEC-1). At the same time, the migration and capillary-network formation of HMEC-1 are promoted through the activation of MAPK/ERK and PI3K/AKT. In vivo tests demonstrate that the HAP-CS-SMSCs-126-Exos successfully promote wound surface re-epithelialization, accelerate angiogenesis, and expedite collagen maturity due to the presence of HAP, CS and SMSCs-126-Exos. Therefore, the HAP-CS-SMSCs-126-Exos possess great potential application for diabetic chronic wound healing, and especially provide the possibility of using exosomes derived from modified cells as a new approach to bring wonderful functionality and controllability in future chronic wound therapy.

Carbohydrate-based amphiphilic nano delivery systems for cancer therapy

Nanoparticles (NPs) are novel drug delivery systems that have been attracting more and more attention in recent years, and have been used for the treatment of cancer, infection, inflammation and other diseases. Among the numerous classes of materials employed for constructing NPs, organic polymers are outstanding due to the flexibility of design and synthesis and the ease of modification and functionalization. In particular, NP based amphiphilic polymers make a great contribution to the delivery of poorly-water soluble drugs. For example, natural, biocompatible and biodegradable products like polysaccharides are widely used as building blocks for the preparation of such drug delivery vehicles. This review will detail carbohydrate based amphiphilic polymeric systems for cancer therapy. Specifically, it focuses on the nature of the polymer employed for the preparation of targeted nanocarriers, the synthetic methods, as well as strategies for the application and evaluation of biological activity. Applications of the amphiphilic polymer systems include drug delivery, gene delivery, photosensitizer delivery, diagnostic imaging and specific ligand-assisted cellular uptake. As a result, a thorough understanding of the relationship between chemical structure and biological properties facilitate the optimal design and rational clinical application of the resulting carbohydrate based nano delivery systems for cancer therapy.

Distinctive polymer micelle designed for siRNA delivery and reversal of MDR1 gene-dependent multidrug resistance

P-glycoprotein (P-gp) plays an importantrole in multidrug resistance (MDR), proved to be one of the major obstacles in cancer chemotherapy. Cationic polymers could specifically deliver siRNA to tumor cells and thus reverse MDR by the downregulation of P-gp. In this study, a triblock copolymer micelle was prepared based on the polymer of N-succinyl-chitosan-poly-l-lysine-palmitic acid (NSC-PLL-PA) to deliver siRNA-P-gp (siRNA-micelle) or doxorubicin (Dox-micelle). The resulting micelle exhibited an efficient binding ability for siRNA and high encapsulation efficiency for Dox, with an average particle size of ∼170 nm. siRNA-micelle and Dox-micellewere instable at low pH, thereby enhancing tumor accumulation and intracellular release of the encapsulated siRNA and Dox. siRNA-micelle micelles could enhance the knockdown efficacy of siRNA by improving the transfection efficiency, downregulating P-gp expression, and passing the drug efflux transporters, thereby improving the therapeutic effects of Dox-micelle. However, P-gp could transfer from HepG2/ADM to HepG2 cells independent of the expression of mdr1, and the acquired resistance could permit tumor cells to survive and develop intrinsic P-gp-mediated resistance, thereby limiting the desired efficiency of chemotherapeutics. This study demonstrated the effectiveness of siRNA-micelle for tumor-targeted delivery, MDR reversal, and provided an effective strategy for the treatment of cancers that develop MDR. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2093-2106, 2017.

NANOMEDICINE: will it offer possibilities to overcome multiple drug resistance in cancer?

This review is written with the purpose to review the current nanomedicine literature and provide an outlook on the developments in utilizing nanoscale drug constructs in treatment of solid cancers as well as in the potential treatment of multi-drug resistant cancers. No specific design principles for this review have been utilized apart from our active choice to avoid results only based on in vitro studies. Few drugs based on nanotechnology have progressed to clinical trials, since most are based only on in vitro experiments which do not give the necessary data for the research to progress towards pre-clinical studies. The area of nanomedicine has indeed spark much attention and holds promise for improved future therapeutics in the treatment of solid cancers. However, despite much investment few targeted therapeutics have successfully progressed to early clinical trials, indicating yet again that the human body is complicated and that much more understanding of the fundamentals of receptor interactions, physics of nanomedical constructs and their circulation in the body is indeed needed. We believe that nanomedical therapeutics can allow for more efficient treatments of resistant cancers, and may well be a cornerstone for RNA based therapeutics in the future given their general need for shielding from the harsh environment in the blood stream.

Overcoming Gene-Delivery Hurdles: Physiological Considerations for Nonviral Vectors

With the use of contemporary tools and techniques, it has become possible to more precisely tune the biochemical mechanisms associated with using nonviral vectors for gene delivery. Consequently, nonviral vectors can incorporate numerous vector compositions and types of genetic cargo to develop diverse genetic therapies. Despite these advantages, gene-delivery strategies using nonviral vectors have poorly translated into clinical success due to preclinical experimental design considerations that inadequately predict therapeutic efficacy. Furthermore, the manufacturing and distribution processes are critical considerations for clinical application that should be considered when developing therapeutic platforms. In this review, we evaluate potential avenues towards improving the transition of gene-delivery technologies from in vitro assessment to human clinical therapy.

Clinical experiences with systemically administered siRNA-based therapeutics in cancer

Small interfering RNA (siRNA)-based therapies are emerging as a promising new anticancer approach, and a small number of Phase I clinical trials involving patients with solid tumours have now been completed. Encouraging results from these pioneering clinical studies show that these new therapeutics can successfully and safely inhibit targeted gene products in patients with cancer, and have taught us important lessons regarding appropriate dosages and schedules. In this Review, we critically assess these Phase I studies and discuss their implications for future clinical trial design. Key challenges and future directions in the development of siRNA-containing anticancer therapeutics are also considered.

Nanoparticle-siRNA: A potential cancer therapy?

PURPOSE

To explore current developments in short interfering RNA (siRNA) delivery systems in nanooncology, in particular nanoparticles that encapsulate siRNA for targeted treatment of cancer. siRNA has a high specificity towards the oncogenic mRNA in cancer cells, while application of nanoparticles can improve stable delivery and enhance efficacy.

METHODS

A literature search was performed using the terms "siRNA", "nanoparticles", "targeted delivery", and "cancer". These databases included Medline, Embase, Cochrane Review, Pubmed, and Scopus.

RESULTS

siRNA anti-cancer drugs utilize endogenous RNAi mechanisms to silence oncogene expression, which promotes cancer remission. However, current delivery methods have poor efficacy, requiring assistance by nanoparticles for successful delivery. Recently several preclinical studies have crossed into clinical trials utilizing siRNA nanoparticle therapeutics.

CONCLUSION

Great potential exists for nano-siRNA drugs in cancer treatment, but issues exist with nanoparticle toxicity and off target siRNA effects. Further research is needed in this rapidly developing and promising field of nano-siRNA drugs.

Evaluation of short-interfering RNAs treatment in experimental rabies due to wild-type virus

We have evaluated the efficacy of short-interfering RNAs targeting the nucleoprotein gene and also the brain immune response in treated and non-treated infected mice. Mice were inoculated with wild-type virus, classified as dog (hv2) or vampire bat (hv3) variants and both groups were treated or leaved as controls. No difference was observed in the lethality rate between treated and non-treated groups, although clinical evaluation of hv2 infected mice showed differences in the severity of clinical disease (p = 0.0006). Evaluation of brain immune response 5 days post-inoculation in treated hv2 group showed no difference among the analyzed genes, whereas after 10 days post-inoculation there was increased expression of 2′,5′-oligoadenylate synthetase 1, tumor necrosis factor alpha, interleukin 12, interferon gamma, and C-X-C motif chemokine 10 associated with higher expression of N gene in the same period (p < 0.0001). In hv2 non-treated group only higher interferon beta expression was found at day 5. The observed differences in results of the immune response genes between treated and non-treated groups is not promising as they had neither impact on mortality nor even a reduction in the expression of N gene in siRNA treated animals. This finding suggests that the use of pre-designed siRNA alone may not be useful in rabies treatment.

Livin contributes to tumor hypoxia-induced resistance to cytotoxic therapies in glioblastoma multiforme

PURPOSE

Tumor hypoxia is one of the crucial microenvironments to promote therapy resistance (TR) in glioblastoma multiforme (GBM). Livin, a member of the family of inhibitor of apoptosis proteins, contributes antiapoptosis. However, the role of tumor hypoxia in Livin regulation and its impact on TR are unclear.

EXPERIMENTAL DESIGN

Livin expression and apoptosis for tumor hypoxic cells derived from human glioblastoma xenografts or in vitro hypoxic stress-treated glioblastoma cells were determined by Western blotting, immunofluorescence imaging, and annexin V staining assay. The mechanism of hypoxia-induced Livin induction was investigated by chromatin immunoprecipitation assay and reporter assay. Genetic and pharmacologic manipulation of Livin was utilized to investigate the role of Livin on tumor hypoxia-induced TR in vitro or in vivo.

RESULTS

The upregulation of Livin expression and downregulation of caspase activity were observed under cycling and chronic hypoxia in glioblastoma cells and xenografts, concomitant with increased TR to ionizing radiation and temozolomide. However, knockdown of Livin inhibited these effects. Moreover, hypoxia activated Livin transcription through the binding of hypoxia-inducible factor-1α to the Livin promoter. The targeted inhibition of Livin by the cell-permeable peptide (TAT-Lp15) in intracerebral glioblastoma-bearing mice demonstrated a synergistic suppression of tumor growth and increased the survival rate in standard-of-care treatment with radiation plus temozolomide.

CONCLUSIONS

These findings indicate a novel pathway that links upregulation of Livin to tumor hypoxia-induced TR in GBM and suggest that targeting Livin using cell-permeable peptide may be an effective therapeutic strategy for tumor microenvironment-induced TR.

Bioreducible polymers for therapeutic gene delivery

Most currently available cationic polymers have significant acute toxicity concerns such as cellular toxicity, aggregation of erythrocytes, and entrapment in the lung capillary bed, largely due to their poor biocompatibility and non-degradability under physiological conditions. To develop more intelligent polymers, disulfide bonds are introduced in the design of biodegradable polymers. Herein, the sustained innovations of biomimetic nano-sized constructs with bioreducible poly(disulfide amine)s demonstrate a viable clinical tool for the treatment of cardiovascular disease, anemia, diabetes, and cancer.