Are RNAi and miRNA therapeutics truly dead?

Transforming Healthcare with Nanomedicine: A SWOT Analysis of Drug Delivery Innovation

Objective

Nanomedicine represents a transformative approach in biomedical applications. This study aims to delineate the application of nanomedicine in the biomedical field through the strengths, weaknesses, opportunities, and threats (SWOT) analysis to evaluate its efficacy and potential in clinical applications.

Methods

The SWOT analysis framework was employed to systematically review and assess the internal strengths and weaknesses, along with external opportunities and threats of nanomedicine. This method provides a balanced consideration of the potential benefits and challenges.

Results

Findings from the SWOT analysis indicate that nanomedicine presents significant potential in drug delivery, diagnostic imaging, and tissue engineering. Nonetheless, it faces substantial hurdles such as safety issues, environmental concerns, and high development costs. Critical areas for development were identified, particularly concerning its therapeutic potential and the uncertainties surrounding long-term effects.

Conclusion

Nanomedicine holds substantial promise in driving medical innovation. However, successful clinical translation requires addressing safety, cost, and regulatory challenges. Interdisciplinary collaboration and comprehensive strategic planning are crucial for the safe and effective application of nanomedicine.

Recent advances in understanding of the mechanisms of RNA interference in insects

We highlight the recent 5 years of research that contributed to our understanding of the mechanisms of RNA interference (RNAi) in insects. Since its first discovery, RNAi has contributed enormously as a reverse genetic tool for functional genomic studies. RNAi is also being used in therapeutics, as well as agricultural crop and livestock production and protection. Yet, for the wider application of RNAi, improvement of its potency and delivery technologies is needed. A mechanistic understanding of every step of RNAi, from cellular uptake of RNAi trigger molecules to targeted mRNA degradation, is key for developing an efficient strategy to improve RNAi technology. Insects provide an excellent model for studying the mechanism of RNAi due to species-specific variations in RNAi efficiency. This allows us to perform comparative studies in insect species with different RNAi sensitivity. Understanding the mechanisms of RNAi in different insects can lead to the development of better strategies to improve RNAi and its application to manage agriculturally and medically important insects.

Unlocking the potential of PROTACs: A comprehensive review of protein degradation strategies in disease therapy

The technology known asPROTACs (PROteolysisTArgeting Chimeras) is a method of protein degradation. Utilising bifunctional small molecules, the ubiquitin-proteosome system (UPS) is used to induce the ubiquitination and degradation of target proteins. In addition to being novel chemical knockdown agents for biological studies that are catalytic, reversible, and rapid, PROTACs used in the treatment for disorders like cancer, immunological disorders, viral diseases, and neurological disorders. The protein degradation field has advanced quickly over the last two years, with a significant rise in research articles on the subject as well as a quick rise in smallmolecule degraders that are currently in or will soon enter the clinical stage. Other new degrading technologies, in addition to PROTAC and molecular glue technology, are also emerging rapidly. In this review article, we mainly focuses on various PROTAC molecules designed with special emphasis on targeted cellular pathways for different diseases i.e., cancer, Viral diseases Immune disorders, Neurodegenerative diseases, etc. We discussed about new technologies based on PROTACs such as Antibody PROTAC, Aptamers, Dual target, Folate caged, TF PROTAC, etc. Also, we listed out the PROTACs which are in clinical trials.

Therapeutic potential of targeting mirnas to prostate cancer tumors: using psma as an active target

Prostate cancer (PC) is a commonly diagnosed malignancy in men and is associated with high mortality rates. Current treatments for PC include surgery, chemotherapy, and radiation therapy. However, recent advances in targeted delivery systems have yielded promising new approaches to PC treatment. As PC epithelial cells express high levels of prostate-specific membrane antigen (PSMA) on the cell surface, new drug conjugates focused on PSMA targeting have been developed. microRNAs (miRNAs) are small noncoding RNAs that regulate posttranscriptional gene expression in cells and show excellent possibilities for use in developing new therapeutics for PC. PSMA-targeted therapies based on a miRNA payload and that selectively target PC cells enhances therapeutic efficacy without eliciting damage to normal surrounding tissue. This review discusses the rationale for utilizing miRNAs to target PSMA, revealing their potential in therapeutic approaches to PC treatment. Different delivery systems for miRNAs and challenges to miRNA therapy are also explored.

Hyaluronate-coated perfluoroalkyl polyamine prodrugs as bioactive siRNA delivery systems for the treatment of peritoneal cancers

RNA interference (RNAi) is an emerging therapeutic modality for cancer, which remains in critical need of effective delivery vectors due to the unfavorable biopharmaceutical properties of small RNAs. Polyamines are essential for functioning of mammalian cells. Dysregulated polyamine metabolism is found in many cancers and has been an attractive therapeutic target in combination therapies. Combination therapies based on drugs that affect polyamine metabolism and nucleic acids promise to enhance anticancer activity due to a cooperative effect on multiple oncogenic pathways. Here, we report bioactive polycationic prodrug (F-PaP) based on an anticancer polyamine analog bisethylnorspermine (BENSpm) modified with perfluoroalkyl moieties. Following encapsulation of siRNA, F-PaP/siRNA nanoparticles were coated with hyaluronic acid (HA) to form ternary nanoparticles HA@F-PaP/siRNA. The presence of perfluoroalkyl moieties and HA reduced cell membrane toxicity and improved stability of the particles with cooperatively enhanced siRNA delivery in pancreatic and colon cancer cell lines. We then tested a therapeutic hypothesis that combining BENSpm with siRNA silencing of polo-like kinase 1 (PLK1) would result in cooperative cancer cell killing. HA@F-PaP/siPLK1 induced polyamine catabolism and cell cycle arrest, leading to enhanced apoptosis in the tested cell lines. The HA-coated nanoparticles facilitated tumor accumulation and contributed to strong tumor inhibition and favorable modulation of the immune tumor microenvironment in orthotopic pancreatic cancer model. Combination anticancer therapy with polyamine prodrug-mediated delivery of siRNA. Hyaluronate coating of the siRNA nanoparticles facilitates selective accumulation in orthotopic pancreatic tumors. Perfluoroalkyl conjugation reduces toxicity and improves gene silencing effect. Nanoparticle treatment induces polyamine catabolism and cell cycle arrest leading to strong tumor inhibition and favorable modulation of immune tumor microenvironment.

[Induced degradation of proteins by PROTACs and other strategies: towards promising drugs]

Targeted protein degradation (TPD), discovered twenty years ago through the PROTAC technology, is rapidly developing thanks to the implication of many scientists from industry and academia. PROTAC chimeras are heterobifunctional molecules able to link simultaneously a protein to be degraded and an E3 ubiquitin ligase. This allows the protein ubiquitination and its degradation by 26S proteasome. PROTACs have evolved from small peptide molecules to small non-peptide and orally available molecules. It was shown that PROTACs are capable to degrade proteins considered as "undruggable" i.e. devoid of well-defined pockets and deep grooves possibly occupied by small molecules. Among these "hard to drug" proteins, several can be degraded by PROTACs: scaffold proteins, BAF complex, transcription factors, Ras family proteins. Two PROTACs are clinically tested for breast (ARV471) and prostate (ARV110) cancers. The protein degradation by proteasome is also induced by other types of molecules: molecular glues, hydrophobic tagging (HyT), HaloPROTACs and homo-PROTACs. Other cellular constituents are eligible to induced degradation: RNA-PROTACs for RNA binding proteins and RIBOTACs for degradation of RNA itself (SARS-CoV-2 RNA). TPD has recently moved beyond the proteasome with LYTACs (lysosome targeting chimeras) and MADTACs (macroautophagy degradation targeting chimeras). Several techniques such as screening platforms together with mathematical modeling and computational design are now used to improve the discovery of new efficient PROTACs.

The Multiple Roles of Hepatitis B Virus X Protein (HBx) Dysregulated MicroRNA in Hepatitis B Virus-Associated Hepatocellular Carcinoma (HBV-HCC) and Immune Pathways

Currently, the treatment of hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) [HBV-HCC] relies on blunt tools that are unable to offer effective therapy for later stage pathogenesis. The potential of miRNA to treat HBV-HCC offer a more targeted approach to managing this lethal carcinoma; however, the complexity of miRNA as an ancillary regulator of the immune system remains poorly understood. This review examines the overlapping roles of HBx-dysregulated miRNA in HBV-HCC and immune pathways and seeks to demonstrate that specific miRNA response in immune cells is not independent of their expression in hepatocytes. This interplay between the two pathways may provide us with the possibility of using candidate miRNA to manipulate this interaction as a potential therapeutic option.

The effector mechanism of siRNA spherical nucleic acids

Spherical nucleic acids (SNAs) are nanostructures formed by chemically conjugating short linear strands of oligonucleotides to a nanoparticle template. When made with modified small interfering RNA (siRNA) duplexes, SNAs act as single-entity transfection and gene silencing agents and have been used as lead therapeutic constructs in several disease models. However, the manner in which modified siRNA duplex strands that comprise the SNA lead to gene silencing is not understood. Herein, a systematic analysis of siRNA biochemistry involving SNAs shows that Dicer cleaves the modified siRNA duplex from the surface of the nanoparticle, and the liberated siRNA subsequently functions in a way that is dependent on the canonical RNA interference mechanism. By leveraging this understanding, a class of SNAs was chemically designed which increases the siRNA content by an order of magnitude through covalent attachment of each strand of the duplex. As a consequence of increased nucleic acid content, this nanostructure architecture exhibits less cell cytotoxicity than conventional SNAs without a decrease in siRNA activity.

Multifunctional Nanodelivery Platform for Maximizing Nucleic Acids Combination Therapy

The silencing of an oncogene with a small interfering RNA (siRNA) is a promising way for cancer therapy. Its efficacy can be further enhanced by integrating with other therapeutics; however, transporting siRNA and other active ingredients to the same location at the same time is challenging. Here, we report a novel multifunctional nanodelivery platform by sequentially layering several functional ingredients, such as siRNAs, microRNAs, peptides, and targeting ligands, onto a core through charge-charge interaction. The prepared nanovectors effectively and programmably delivered multiple active components to maximize therapeutic combination with minimal off-targeting effects.

NAD(P)H:quinone oxidoreductase 1 determines radiosensitivity of triple negative breast cancer cells and is controlled by long non-coding RNA NEAT1

Radioresistant cells cause recurrence in patients with breast cancer after they undergo radiation therapy. The molecular mechanisms by which cancer cells obtain radioresistance should be understood to develop radiation-sensitizing agents. Results showed that the protein expression and activity of NAD(P)H:quinone oxidoreductase 1 (NQO1) were upregulated in radioresistant MDA-MB-231 triple-negative breast cancer (TNBC) cells. NQO1 knockdown inhibited the proliferation of NQO1 expressing Hs578t TNBC cells or the radioresistant MDA-MB-231 cells, whereas NOQ1 overexpression increased the survival of MDA-MB-231 cells, which lack of NQO1 expression originally, under irradiation. The cytotoxicity of β-lapachone, an NQO1-dependent bioactivatable compound, was greater in radioresistant MDA-MB-231 cells than in parental cells. β-lapachone displayed a radiosensitization effect on Hs578t or radioresistant MBDA-MB-231 cells. The expression of the long noncoding RNA NEAT1 positively regulated the NQO1 expression in radioresistant MDA-MB-231 cells at a translational level rather than at a transcription level. The inhibition of the NEAT1 expression through the CRISPR-Cas9 method increased the sensitivity of radioresistant MDA-MB-231 cells to radiation and decreased their proliferation, the activity of cancer stem cells, and the expression of stemness genes, including BMI1, Oct4, and Sox2. In conclusion, the NQO1 expression in triple-negative breast cancer cells determined their radiosensitivity and was controlled by NEAT1. In addition, NOQ1 bioactivatable compounds displayed potential for application in the development of radiation sensitizers in breast cancer.

Editorial focus: understanding off-target effects as the key to successful RNAi therapy

With the first RNA interference (RNAi) drug (ONPATTRO (patisiran)) on the market, we witness the RNAi therapy field reaching a critical turning point, when further improvements in drug candidate design and delivery pipelines should enable fast delivery of novel life changing treatments to patients. Nevertheless, ignoring parallel development of RNAi dedicated in vitro pharmacological profiling aiming to identify undesirable off-target activity may slow down or halt progress in the RNAi field. Since academic research is currently fueling the RNAi development pipeline with new therapeutic options, the objective of this article is to briefly summarize the basics of RNAi therapy, as well as to discuss how to translate basic research into better understanding of related drug candidate safety profiles early in the process.

Lipid nanocarriers for microRNA delivery

Non-coding RNAs (ncRNAs) like microRNAs (miRNAs) or small interference RNAs (siRNAs) with their power to selectively silence any gene of interest enable the targeting of so far 'undruggable' proteins and diseases. Such RNA molecules have gained much attention from biotech and pharmaceutical companies, which led to the first Food and Drug Administration (FDA) approved ncRNA therapeutic in 2018. However, the main barrier in clinical practice of ncRNAs is the lack of an effective delivery system that can protect the RNA molecules from nuclease degradation, deliver them to specific tissues and cell types, and release them into the cytoplasm of the targeted cells, all without inducing adverse effects. For that reason, drug delivery approaches, formulations, technologies and systems for transporting pharmacological ncRNA compounds to achieve a diagnostic or therapeutic effect in the human body are in demand. Here, we review the development of therapeutic lipid-based nanoparticles for delivery of miRNAs, one class of endogenous ncRNAs with specific regulatory functions. We outline challenges and opportunities for advanced miRNA-based therapies, and discuss the complexity associated with the delivery of functional miRNAs. Novel strategies are addressed how to deal with the most critical points in miRNA delivery, such as toxicity, specific targeting of disease sites, proper cellular uptake and endosomal escape of miRNAs. Current fields of application and various preclinical settings involving miRNA therapeutics are discussed, providing an outlook to future clinical approaches. Following the current trends and technological developments in nanomedicine exciting new delivery systems for ncRNA-based therapeutics can be expected in upcoming years.

Unveiling the druggable RNA targets and small molecule therapeutics

The increasing appreciation for the crucial roles of RNAs in infectious and non-infectious human diseases makes them attractive therapeutic targets. Coding and non-coding RNAs frequently fold into complex conformations which, if effectively targeted, offer opportunities to therapeutically modulate numerous cellular processes, including those linked to undruggable protein targets. Despite the considerable skepticism as to whether RNAs can be targeted with small molecule therapeutics, overwhelming evidence suggests the challenges we are currently facing are not outside the realm of possibility. In this review, we highlight the most recent advances in molecular techniques that have sparked a revolution in understanding the RNA structure-to-function relationship. We bring attention to the application of these modern techniques to identify druggable RNA targets and to assess small molecule binding specificity. Finally, we discuss novel screening methodologies that support RNA drug discovery and present examples of therapeutically valuable RNA targets.

Nanopharmaceuticals and nanomedicines currently on the market: challenges and opportunities

There has been a revolution in nanotechnology and nanomedicine. Since 1980, there has been a remarkable increase in approved nano-based pharmaceutical products. These novel nano-based systems can either be therapeutic agents themselves, or else act as vehicles to carry different active pharmaceutical agents into specific parts of the body. Currently marketed nanostructures include nanocrystals, liposomes and lipid nanoparticles, PEGylated polymeric nanodrugs, other polymers, protein-based nanoparticles and metal-based nanoparticles. A range of issues must be addressed in the development of these nanostructures. Ethics, market size, possibility of market failure, costs and commercial development, are some topics which are on the table to be discussed. After passing all the ethical and biological assessments, and satisfying the investors as to future profitability, only a handful of these nanoformulations, successfully obtained marketing approval. We survey the range of nanomedicines that have received regulatory approval and are marketed. We discuss ethics, costs, commercial development and possible market failure. We estimate the global nanomedicine market size and future growth. Our goal is to summarize the different approved nanoformulations on the market, and briefly cover the challenges and future outlook.

Promise of chemokine network-targeted nanoparticles in combination nucleic acid therapies of metastatic cancer

Chemokines and chemokine receptors play key roles in cancer progression and metastasis. Although multiple chemokines and chemokine receptors have been investigated, inhibition of CXCR4 emerged as one of the most promising approaches in combination cancer therapy, especially when focused on the metastatic disease. Small RNA molecules, such as small interfering RNA (siRNA) and microRNA (miRNA), represent new class of therapeutics for cancer treatment through RNA interference-mediated gene silencing. However, the clinical applicability of siRNA and miRNA is severely limited by the lack of effective delivery systems. There is a significant therapeutic potential for CXCR4-targeted nanomedicines in combination with the delivery of siRNA and miRNA in cancer. Recently developed CXCR4-targeted polymeric drugs and nanomedicines, including cyclam- and chloroquine-based polymeric CXCR4 antagonists are introduced here and their ability to deliver functional siRNA and miRNA is discussed. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Understanding RNA modifications: the promises and technological bottlenecks of the 'epitranscriptome'

The discovery of mechanisms that alter genetic information via RNA editing or introducing covalent RNA modifications points towards a complexity in gene expression that challenges long-standing concepts. Understanding the biology of RNA modifications represents one of the next frontiers in molecular biology. To this date, over 130 different RNA modifications have been identified, and improved mass spectrometry approaches are still adding to this list. However, only recently has it been possible to map selected RNA modifications at single-nucleotide resolution, which has created a number of exciting hypotheses about the biological function of RNA modifications, culminating in the proposition of the ‘epitranscriptome’. Here, we review some of the technological advances in this rapidly developing field, identify the conceptual challenges and discuss approaches that are needed to rigorously test the biological function of specific RNA modifications.

Emerging aspects of microRNA interaction with TMPRSS2-ERG and endocrine therapy

Prostate cancer (PCa) is the most common malignancy detected in males and the second most common cause of cancer death in western countries. The development of the prostate gland, is finely regulated by androgens which modulate also its growth and function. Importantly, androgens exert a major role in PCa formation and progression and one of the hypothesized mechanism proposed has been linked to the chromosomal rearrangement of the androgen regulated gene TMPRSS2 with ERG. Androgens have been therefore used as main target for therapies in the past. However, despite the development of endocrine therapies (e.g. androgen ablation), when PCa progress, tumors become resistant to this therapeutic castration and patients develop incurable metastases. A strategy to better understand how patients respond to therapy, in order to achieve a better patient stratification, consists in monitoring the levels of small noncoding RNAs (microRNAs). microRNAs are a class of small molecules that regulate protein abundance and their application as biomarkers to monitor disease progression has been intensely studied in the last years. In this review, we highlight the interactions between microRNAs and endocrine-related aspects of PCa in tissues. We focus on the modulation of TMPRSS2-ERG and Glucocorticoid Receptor (GR) by microRNAs and detail the influence of steroidal hormonal therapies on microRNAs expression.

Engineered Hydrogels in Cancer Therapy and Diagnosis

Over the last decade, numerous investigations have attempted to clarify the intricacies of tumor development to propose effective approaches for cancer treatment. Thanks to the unique properties of hydrogels, researchers have made significant progress in tumor model reconstruction, tumor diagnosis, and associated therapies. Notably, hydrogel-based systems can be adjusted to respond to cancer-specific hallmarks and/or external stimuli. These well-known drug reservoirs can be used as smart carriers for multiple cargos, including both naked and nanoparticle-encapsulated chemotherapeutics, genes, and radioisotopes. Recent works have attempted to specialize hydrogels for cancer research; we comprehensively review this topic for the first time, synthesizing past results and defining paths for future work.

Targeted Protein Degradation: from Chemical Biology to Drug Discovery

Traditional pharmaceutical drug discovery is almost exclusively focused on directly controlling protein activity to cure diseases. Modulators of protein activity, especially inhibitors, are developed and applied at high concentration to achieve maximal effects. Thereby, reduced bioavailability and off-target effects can hamper compound efficacy. Nucleic acid-based strategies that control protein function by affecting expression have emerged as an alternative. However, metabolic stability and broad bioavailability represent development hurdles that remain to be overcome for these approaches. More recently, utilizing the cell's own protein destruction machinery for selective degradation of essential drivers of human disorders has opened up a new and exciting area of drug discovery. Small-molecule-induced proteolysis of selected substrates offers the potential of reaching beyond the limitations of the current pharmaceutical paradigm to expand the druggable target space.

Oral nucleic acid therapy using multicompartmental delivery systems

Nucleic acid-based therapeutics has the potential for treating numerous diseases by correcting abnormal expression of specific genes. Lack of safe and efficacious delivery strategies poses a major obstacle limiting clinical advancement of nucleic acid therapeutics. Oral route of drug administration has greater delivery challenges, because the administered genes or oligonucleotides have to bypass degrading environment of the gastrointestinal (GI) tract in addition to overcoming other cellular barriers preventing nucleic acid delivery. For efficient oral nucleic acid delivery, vector should be such that it can protect encapsulated material during transit through the GI tract, facilitate efficient uptake and intracellular trafficking at desired target sites, along with being safe and well tolerated. In this review, we have discussed multicompartmental systems for overcoming extracellular and intracellular barriers to oral delivery of nucleic acids. A nanoparticles-in-microsphere oral system-based multicompartmental system was developed and tested for in vivo gene and small interfering RNA delivery for treating colitis in mice. This system has shown efficient transgene expression or gene silencing when delivered orally along with favorable downstream anti-inflammatory effects, when tested in a mouse model of intestinal bowel disease. WIREs Nanomed Nanobiotechnol 2018, 10:e1478. doi: 10.1002/wnan.1478 This article is categorized under: Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Nanocarriers for microRNA delivery in cancer medicine

The number of deaths caused by cancer is expected to increase partly due to the lack of selectivity and undesirable systemic effects of current treatments. Advances in the understanding of microRNA (miRNA) functions and the ideal properties of nanosystems have brought increasing attention to the application of nanomedicine to cancer therapy. This review covers the different miRNA therapeutic strategies and delivery challenges for its application in cancer medicine. Current trends in inorganic, polymeric and lipid nanocarrier development for miRNA replacement or inhibition are summarized. To achieve clinical success, in-depth knowledge of the effects of the promotion or inhibition of specific miRNAs is required. To establish the dose and the length of treatment, it will be necessary to study the duration of gene silencing. Additionally, efforts should be made to develop specifically targeted delivery systems to cancer cells to reduce doses and unwanted effects. In the near future, the combination of miRNAs with other therapeutic approaches is likely to play an important role in addressing the heterogeneity of cancer.

Gold Nanoparticle Approach to the Selective Delivery of Gene Silencing in Cancer-The Case for Combined Delivery?

Gene therapy arises as a great promise for cancer therapeutics due to its potential to silence genes involved in tumor development. In fact, there are some pivotal gene drivers that suffer critical alterations leading to cell transformation and ultimately to tumor growth. In this vein, gene silencing has been proposed as an active tool to selectively silence these molecular triggers of cancer, thus improving treatment. However, naked nucleic acid (DNA/RNA) sequences are reported to have a short lifetime in the body, promptly degraded by circulating enzymes, which in turn speed up elimination and decrease the therapeutic potential of these drugs. The use of nanoparticles for the effective delivery of these silencers to the specific target locations has allowed researchers to overcome this issue. Particularly, gold nanoparticles (AuNPs) have been used as attractive vehicles for the target-specific delivery of gene-silencing moieties, alone or in combination with other drugs. We shall discuss current trends in AuNP-based delivery of gene-silencing tools, considering the promising road ahead without overlooking existing concerns for their translation to clinics.

Multifunctional silver nanocluster-hybrid oligonucleotide vehicle for cell imaging and microRNA-targeted gene silencing

Novel therapeutics is urgently needed to prevent cancer-related deaths. MicroRNAs that act as tumor suppressors have been recognized as a next-generation tumor therapy, and the restoration of tumor-suppressive microRNAs using microRNA replacements or mimics may be a less toxic, more effective strategy due to fewer off-target effects. Here, we designed the novel multifunctional oligonucleotide nanocarrier complex composed of a tumor-targeting aptamer sequence specific to mucin 1 (MUC1), poly-cytosine region for fluorescent silver nanocluster (AgNC) synthesis, and complimentary sequence for microRNA miR-34a loading. MiR-34a was employed because of its therapeutic effect of inhibiting oncogene expression and inducing apoptosis in carcinomas. By monitoring the intrinsic fluorescence of AgNC, it was clearly shown that the constructed complex (MUC1-AgNC_m-miR-34a) enters MCF-7 cells. To evaluate the efficacy of this nanocarrier for microRNA delivery, we investigated the gene and protein expression levels of downstream miR-34a targets (BCL-2, CDK6, and CCND1) by quantitative PCR and western blotting, respectively, and the results indicated their effective inhibition by miR-34a. This novel multifunctional AgNC-based nanocarrier can aid in improving the efficacy of breast cancer theranostics.

Nanocarrier-based co-delivery of small molecules and siRNA/miRNA for treatment of cancer

Aberrant gene expression can trigger several vital molecular events that not only result in carcinogenesis but also cause chemoresistance, metastasis and relapse. Gene-based therapies using siRNA/miRNA have been suggested as new treatment method to improve the current regimen. Although these agents can restore the normal molecular cascade thereby resensitizing the cancer cells, delivering a standard regimen (either subsequently or simultaneously) is necessary to achieve the therapeutic benefit. However, co-delivery using a single carrier could give an additional advantage of similar biodistribution profile of the loaded agents. While much research has been carried out in this field in recent years, challenges involved in designing combination formulations including efficient coloading, stability, appropriate biodistribution and target specificity have hampered their clinical translation. This article highlights current aspects of nano-carriers used for co-delivery of small molecules and genes to treat cancer.

Potent Anti-seizure Effects of Locked Nucleic Acid Antagomirs Targeting miR-134 in Multiple Mouse and Rat Models of Epilepsy

Current anti-epileptic drugs (AEDs) act on a limited set of neuronal targets, are ineffective in a third of patients with epilepsy, and do not show disease-modifying properties. MicroRNAs are small noncoding RNAs that regulate levels of proteins by post-transcriptional control of mRNA stability and translation. MicroRNA-134 is involved in controlling neuronal microstructure and brain excitability and previous studies showed that intracerebroventricular injections of locked nucleic acid (LNA), cholesterol-tagged antagomirs targeting microRNA-134 (Ant-134) reduced evoked and spontaneous seizures in mouse models of status epilepticus. Translation of these findings would benefit from evidence of efficacy in non-status epilepticus models and validation in another species. Here, we report that electrographic seizures and convulsive behavior are strongly reduced in adult mice pre-treated with Ant-134 in the pentylenetetrazol model. Pre-treatment with Ant-134 did not affect the severity of status epilepticus induced by perforant pathway stimulation in adult rats, a toxin-free model of acquired epilepsy. Nevertheless, Ant-134 post-treatment reduced the number of rats developing spontaneous seizures by 86% in the perforant pathway stimulation model and Ant-134 delayed epileptiform activity in a rat ex vivo hippocampal slice model. The potent anticonvulsant effects of Ant-134 in multiple models may encourage pre-clinical development of this approach to epilepsy therapy.

Targeted Protein Degradation by Small Molecules

Protein homeostasis networks are highly regulated systems responsible for maintaining the health and productivity of cells. Whereas therapeutics have been developed to disrupt protein homeostasis, more recently identified techniques have been used to repurpose homeostatic networks to effect degradation of disease-relevant proteins. Here, we review recent advances in the use of small molecules to degrade proteins in a selective manner. First, we highlight all-small-molecule techniques with direct clinical application. Second, we describe techniques that may find broader acceptance in the biomedical research community that require little or no synthetic chemistry. In addition to serving as innovative research tools, these new approaches to control intracellular protein levels offer the potential to develop novel therapeutics targeting proteins that are not currently pharmaceutically vulnerable.

Current preclinical small interfering RNA (siRNA)-based conjugate systems for RNA therapeutics

Recent promising clinical results of RNA therapeutics have drawn big attention of academia and industries to RNA therapeutics and their carrier systems. To improve their feasibility in clinics, systemic evaluations of currently available carrier systems under clinical trials and preclinical studies are needed. In this review, we focus on recent noticeable preclinical studies and clinical results regarding siRNA-based conjugates for clinical translations. Advantages and drawbacks of siRNA-based conjugates are discussed, compared to particle-based delivery systems. Then, representative siRNA-based conjugates with aptamers, peptides, carbohydrates, lipids, polymers, and nanostructured materials are introduced. To improve feasibility of siRNA conjugates in preclinical studies, several considerations for the rational design of siRNA conjugates in terms of cleavability, immune responses, multivalent conjugations, and mechanism of action are also presented. Lastly, we discuss lessons from previous preclinical and clinical studies related to siRNA conjugates and perspectives of their clinical applications.

MicroRNAs in glaucoma and neurodegenerative diseases

MicroRNAs (miRNAs) constitute a class of short, non-coding RNAs, which have important role in post-transcriptional regulation of genes expression by base-pairing with their target messenger RNA (mRNA). In recent years, miRNAs biogenesis, gene silencing mechanism and implication in various diseases have been thoroughly investigated. Many scientific findings indicate the altered expression of specific miRNA in the brains of patients affected by neurodegenerative diseases (NDs) such as Alzheimer's disease, Parkinson's disease and Huntington disease. The progressive optic nerve neuropathy associated with changed miRNA profile was also observed during glaucoma development. This suggests that the miRNAs may have a crucial role in these disorders, contributing to the neuronal cell death. A better understanding of molecular mechanism of these disorders will open a new potential way of ND treatment. In this review, the miRNAs role in particular neurodegenerative disorders and their possible application in medicine was discussed.

The notorious R.N.A. in the spotlight - drug or target for the treatment of disease

mRNA is an attractive drug target for therapeutic interventions. In this review we highlight the current state, clinical trials, and developments in antisense therapy, including the classical approaches like RNaseH-dependent oligomers, splice-switching oligomers, aptamers, and therapeutic RNA interference. Furthermore, we provide an overview on emerging concepts for using RNA in therapeutic settings including protein replacement by in-vitro-transcribed mRNAs, mRNA as vaccines and anti-allergic drugs. Finally, we give a brief outlook on early-stage RNA repair approaches that apply endogenous or engineered proteins in combination with short RNAs or chemically stabilized oligomers for the re-programming of point mutations, RNA modifications, and frame shift mutations directly on the endogenous mRNA.

The role of microRNAs in bone metastasis

The skeleton represents a common site of metastases for osteotropic cancers such as prostate and breast tumors and novel therapeutic targets and new markers for the monitoring of bone lesions are urgently needed. The formation of bone metastases is a complex process that starts at the level of the confined tumor and that is characterized by a dynamic crosstalk between the primary cancer and the future metastatic site, the bone. Factors released by the primary tumor contribute to prepare a fertile “soil”, where a “pre-metastatic niche” is established prior to future colonization by cancer cells. When the primary cancer progress from the confined disease to its invasive phase, tumor cells will acquire an invasive phenotype, enter into the circulation and colonize the previously prepared site where they will establish a “metastatic niche”. Among the variety of molecules that participate in the metastatic cascade, microRNAs are a class of small non-coding RNA that play an important role in the development of metastatic bone lesions. Many studies have addressed the role of small non-coding RNAs (miRs) in metastasis in osteotropic cancers and have highlighted the role of miRs as oncogenes (oncomiRs) or tumor suppressor miRs.

In this review we present describe the role of miRs in the processing of the supportive bone microenvironment prior and after the bone colonization by cancer cells. Finally, future therapeutic strategies and perspectives are also discussed.

RNA nanomedicines: the next generation drugs?

RNA therapeutics could represent the next generation personalized medicine. The variety of RNA molecules that can inhibit the expression of any mRNA using, for example, RNA interference (RNAi) strategies, or increase the expression of a given protein using modified mRNA together with new gene editing strategies open new avenues for manipulating the fate of diseased cells while leaving healthy cells untouched. In addition, these therapeutic RNA molecules can maximize the treatment of diseases and minimize its adverse effects. Yet, the promise of RNA therapeutics is hindered by the lack of efficient delivery strategies to selectively target these molecules into specific cells. Herein, we will focus on the challenges and opportunities of the delivery of therapeutic RNAi molecules into cancer cells with special emphasis on solid tumors. Solid tumors represent more than 80 percent of cancers and some are very challenging to treat, not merely due to physiological barriers but also since the tumor microenvironment (TME) is a complex milieu of accessory cells besides the cancerous cells. In this review, we will highlight various limiting factors to successful delivery, current clinical achievements and future outlook focusing on RNAi therapeutics to the TME.

Metastatic breast cancer: the potential of miRNA for diagnosis and treatment monitoring

Breast cancer affects approximately 12 % women worldwide and results in 14 % of all cancer-related fatalities. Breast cancer is commonly categorized into one of four main subtypes (luminal A, luminal B, human epidermal growth factor receptor 2 (HER2) positive and basal), indicating molecular characteristics and informing treatment regimes. The most severe form of breast cancer is metastasis, when the tumour spreads from the breast tissue to other parts of the body. Significantly, the primary tumour subtype affects rates and sites of metastasis. Currently, up to 5 % of patients present with incurable metastasis, with an additional 10–15 % of patients going on to develop metastasis within 3 years of diagnosis. MicroRNAs (miRNAs) are short 21–25 long nucleotides that have been shown to significantly affect gene expression. Currently, >2000 miRNAs have been identified and significantly, specific miRNAs have been found associated with diseases states. Importantly, miRNAs are found circulating in the blood, presenting an opportunity to use these circulating disease-related miRNAs as biomarkers. Clearly, the identification of circulating miRNA specific to metastatic breast cancer presents a unique opportunity for early disease identification and for monitoring disease burden. Currently however, few groups have identified miRNA associated with metastatic breast cancer. Here, we review the literature surrounding the identification of metastatic miRNA in breast cancer patients, highlighting key areas where miRNA biomarker discovery could be beneficial, identifying key concepts, recognizing critical areas requiring further research and discussing potential problems.

Disregarded Effect of Biological Fluids in siRNA Delivery: Human Ascites Fluid Severely Restricts Cellular Uptake of Nanoparticles

Small interfering RNA (siRNA) offers a great potential for the treatment of various diseases and disorders. Nevertheless, inefficient in vivo siRNA delivery hampers its translation into the clinic. While numerous successful in vitro siRNA delivery stories exist in reduced-protein conditions, most studies so far overlook the influence of the biological fluids present in the in vivo environment. In this study, we compared the transfection efficiency of liposomal formulations in Opti-MEM (low protein content, routinely used for in vitro screening) and human undiluted ascites fluid obtained from a peritoneal carcinomatosis patient (high protein content, representing the in vivo situation). In Opti-MEM, all formulations are biologically active. In ascites fluid, however, the biological activity of all lipoplexes is lost except for lipofectamine RNAiMAX. The drop in transfection efficiency was not correlated to the physicochemical properties of the nanoparticles, such as premature siRNA release and aggregation of the nanoparticles in the human ascites fluid. Remarkably, however, all of the formulations except for lipofectamine RNAiMAX lost their ability to be taken up by cells following incubation in ascites fluid. To take into account the possible effects of a protein corona formed around the nanoparticles, we recommend always using undiluted biological fluids for the in vitro optimization of nanosized siRNA formulations next to conventional screening in low-protein content media. This should tighten the gap between in vitro and in vivo performance of nanoparticles and ensure the optimal selection of nanoparticles for further in vivo studies.