The Race of 10 Synthetic RNAi-Based Drugs to the Pharmaceutical Market

The advancement of siRNA-based nanomedicine for tumor therapy

Small interfering RNA (siRNA) has been proved to be able to effectively down-regulate gene expression through the RNAi mechanism. Thus, siRNA-based drugs have become one of the hottest research directions due to their high efficiency and specificity. However, challenges such as instability, off-target effects and immune activation hinder their clinical application. This review explores the mechanisms of siRNA and the challenges in siRNA-based tumor therapy. It highlights the use of various nanomaterials - including lipid nanoparticles, polymeric nanoparticles and inorganic nanoparticles - as carriers for siRNA delivery in different therapeutic modalities. The application strategies of siRNA-based nanomedicine in chemotherapy, phototherapy and immunotherapy are discussed in detail, along with recent clinical advancements. Aiming to provide insights for future research and therapeutic approaches.

Enhancing siRNA cancer therapy: Multifaceted strategies with lipid and polymer-based carrier systems

Cancers are increasing in prevalence and many challenges remain for their treatment, such as chemoresistance and toxicity. In this context, siRNA-based therapeutics have many potential advantages for cancer therapies as a result of their ability to reduce or prevent expression of specific cancer-related genes. However, the direct delivery of naked siRNA is hindered by issues like enzymatic degradation, insufficient cellular uptake, and poor pharmacokinetics. Hence, the discovery of a safe and efficient delivery vehicle is essential. This review explores various lipid and polymer-based delivery systems for siRNA in cancer treatment. Both polymers and lipids have garnered considerable attention as carriers for siRNA delivery. While all of these systems protect siRNA and enhance transfection efficacy, each exhibits its unique strengths. Lipid-based delivery systems, for instance, demonstrate high entrapment efficacy and utilize cost-effective materials. Conversely, polymeric-based delivery systems offer advantages through chemical modifications. Nonetheless, certain drawbacks still limit their usage. To address these limitations, combining different materials in formulations (lipid, polymer, or targeting agent) could enhance pharmaceutical properties, boost transfection efficacy, and reduce side effects. Furthermore, co-delivery of siRNA with other therapeutic agents presents a promising strategy to overcome cancer resistance. Lipid-based delivery systems have been demonstrated to encapsulate many therapeutic agents and with high efficiency, but most are limited in terms of the functionalities they display. In contrast, polymeric-based delivery systems can be chemically modified by a wide variety of routes to include multiple components, such as release or targeting elements, from the same materials backbone. Accordingly, by incorporating multiple materials such as lipids, polymers, and/or targeting agents in RNA formulations it is possible to improve the pharmaceutical properties and therapeutic efficacy while reducing side effects. This review focuses on strategies to improve siRNA cancer treatments and discusses future prospects in this important field.

Advancements in clinical RNA therapeutics: Present developments and prospective outlooks

RNA molecules have emerged as promising clinical therapeutics due to their ability to target "undruggable" proteins or molecules with high precision and minimal side effects. Nevertheless, the primary challenge in RNA therapeutics lies in rapid degradation and clearance from systemic circulation, the inability to traverse cell membranes, and the efficient intracellular delivery of bioactive RNA molecules. In this review, we explore the implications of RNAs in diseases and provide a chronological overview of the development of RNA therapeutics. Additionally, we summarize the technological advances in RNA-screening design, encompassing various RNA databases and design platforms. The paper then presents an update on FDA-approved RNA therapeutics and those currently undergoing clinical trials for various diseases, with a specific emphasis on RNA medicine and RNA vaccines.

Discovery platforms for RNA therapeutics

RNA therapeutics are emerging as a unique opportunity to drug currently "undruggable" molecules and diseases. While their advantages over conventional, small molecule drugs, their therapeutic implications and the tools for their effective in vivo delivery have been extensively reviewed, little attention has been so far paid to the technological platforms exploited for the discovery of RNA therapeutics. Here, we provide an overview of the existing platforms and ex vivo assays for RNA discovery, their advantages and disadvantages, as well as their main fields of application, with specific focus on RNA therapies that have reached either phase 3 or market approval.

Treatment with siRNAs is commonly associated with GPX4 up-regulation and target knockdown-independent sensitization to ferroptosis

Small interfering RNAs (siRNAs) are widely used in biomedical research and in clinical trials. Here, we demonstrate that siRNA treatment is commonly associated with significant sensitization to ferroptosis, independently of the target protein knockdown. Genetically targeting mitochondrial antiviral-signaling protein (MAVS) reversed the siRNA-mediated sensitizing effect, but no activation of canonical MAVS signaling, which involves phosphorylation of IkBα and interferon regulatory transcription factor 3 (IRF3), was observed. In contrast, MAVS mediated a noncanonical signal resulting in a prominent increase in mitochondrial ROS levels, and increase in the BACH1/pNRF2 transcription factor ratio and GPX4 up-regulation, which was associated with a 50% decrease in intracellular glutathione levels. We conclude that siRNAs commonly sensitize to ferroptosis and may severely compromise the conclusions drawn from silencing approaches in biomedical research. Finally, as ferroptosis contributes to a variety of pathophysiological processes, we cannot exclude side effects in human siRNA-based therapeutical concepts that should be clinically tested.

RNA interference in the era of nucleic acid therapeutics

Two decades of research on RNA interference (RNAi) have transformed a breakthrough discovery in biology into a robust platform for a new class of medicines that modulate mRNA expression. Here we provide an overview of the trajectory of small-interfering RNA (siRNA) drug development, including the first approval in 2018 of a liver-targeted siRNA interference (RNAi) therapeutic in lipid nanoparticles and subsequent approvals of five more RNAi drugs, which used metabolically stable siRNAs combined with N-acetylgalactosamine ligands for conjugate-based liver delivery. We also consider the remaining challenges in the field, such as delivery to muscle, brain and other extrahepatic organs. Today's RNAi therapeutics exhibit high specificity, potency and durability, and are transitioning from applications in rare diseases to widespread, chronic conditions.

Recent insights into the functions and mechanisms of antisense RNA: emerging applications in cancer therapy and precision medicine

The antisense RNA molecule is a unique DNA transcript consisting of 19-23 nucleotides, characterized by its complementary nature to mRNA. These antisense RNAs play a crucial role in regulating gene expression at various stages, including replication, transcription, and translation. Additionally, artificial antisense RNAs have demonstrated their ability to effectively modulate gene expression in host cells. Consequently, there has been a substantial increase in research dedicated to investigating the roles of antisense RNAs. These molecules have been found to be influential in various cellular processes, such as X-chromosome inactivation and imprinted silencing in healthy cells. However, it is important to recognize that in cancer cells; aberrantly expressed antisense RNAs can trigger the epigenetic silencing of tumor suppressor genes. Moreover, the presence of deletion-induced aberrant antisense RNAs can lead to the development of diseases through epigenetic silencing. One area of drug development worth mentioning is antisense oligonucleotides (ASOs), and a prime example of an oncogenic trans-acting long noncoding RNA (lncRNA) is HOTAIR (HOX transcript antisense RNA). NATs (noncoding antisense transcripts) are dysregulated in many cancers, and researchers are just beginning to unravel their roles as crucial regulators of cancer's hallmarks, as well as their potential for cancer therapy. In this review, we summarize the emerging roles and mechanisms of antisense RNA and explore their application in cancer therapy.

Serum MicroRNA profiles in chronic hepatitis C Egyptian patients before and after combined sofosbuvir and daclatasvir treatment

BACKGROUND

MicroRNAs (miR) are small sequence of nucleotides that can affect multiple genes involved in the hepatitis C virus (HCV) life cycle and disease development. The purpose of the present study was to investigate the clinical significance of serum microRNA profiles in a cohort of Egyptian patients with chronic HCV infection before and after combined sofosbuvir and daclatasvir treatment, as well as to gain a better understanding of the exact interaction mechanism in HCV transcriptional activity via differentially expressed miRNAs. For 12 weeks, 50 patients were eligible for and received sofosbuvir (400 mg daily) and daclatasvir (60 mg daily) treatment. Each patient's blood was obtained twice: once before therapy began and again three months afterwards.

RESULTS

The current study found that serum levels of circulating miR-122, miR-221, miR-23a, miR-125, miR-217, miR-224, and miR-181a were high in HCV pre-treatment patients, but after 12 weeks of direct-acting antiviral (DAAs) treatment, there was a statistically significant reduction in expression levels of miR-122, miR-221, miR-23a, miR-125, miR-217, and miR-224 (p < 0.001). There is no statistical significance for miR-181a.

CONCLUSION

The key differentially expressed microRNAs before and after the direct-acting antiviral (DAA) regimen were connected to the dynamics of chronic HCV infection, suggesting their potential as predictive biomarkers for HCV clearance after sofosbuvir and daclatasvir therapy.

Advancing cancer treatment: in vivo delivery of therapeutic small noncoding RNAs

In recent years, small non-coding RNAs (ncRNAs) have emerged as a new player in the realm of cancer therapeutics. Their unique capacity to directly modulate genetic networks and target oncogenes positions them as valuable complements to existing small-molecule drugs. Concurrently, the advancement of small ncRNA-based therapeutics has rekindled the pursuit of efficacious in vivo delivery strategies. In this review, we provide an overview of the most current clinical and preclinical studies in the field of small ncRNA-based cancer therapeutics. Furthermore, we shed light on the pivotal challenges hindering the successful translation of these promising therapies into clinical practice, with a specific focus on delivery methods, aiming to stimulate innovative approaches to address this foundational aspect of cancer treatment.

Innate immune regulations and various siRNA modalities

RNAi therapeutics are designed to produce the precise silencing effects against the gene-linked diseases which were known to be untreatable in the past. The highly immunostimulatory nature of siRNA enhances the off-target effects and easily get attacked by nucleases; hence, their modulation is essentially required for accurate alterations to be made in the structures to intensify the pharmacological attributes. The phosphonate modifications act as shield against undue phosphorylation effects, and the molecular changes in ribose sugar lowers the level of immunogenicity and increases the binding efficacy. When bases are substituted with virtual/or pseudo bases, they eventually reduce the off-target effects. These changes modulate the nucleic acid sensors and control the hyper-activation of innate immune response. Various modification designs based on STC (universal pattern), ESC, ESC + (advanced patterns) and disubstrate have been explored to silence the gene expression of various diseases e.g., hepatitis, HIV, influenza, RSV, CNV and acute kidney injury. This review describes the various innovative siRNA therapeutics and their implications on the developed immune regulations to silence the disease effects. siRNA causes the silencing effects through RISC processing. The innate immune signalling is induced by both TLR-dependent and TLR-independent pathways. Modification chemistries are utilized to modulate the immune response.

RNA nanotechnology: A new chapter in targeted therapy

Nanoparticles have been widely studied in the fields of biotechnology, pharmacy, optics and medicine and have broad application prospects. Numerous studies have shown significant interest in utilizing nanoparticles for chemically coating or coupling drugs, aiming to address the challenges of drug delivery, including degradability and uncertainty. Furthermore, the utilization of lipid nanoparticles loaded with novel coronavirus antigen mRNA to control the COVID-19 pandemic has led to a notable surge in research on nanoparticle vaccines. Hence, nanoparticles have emerged as a crucial delivery system for disease prevention and treatment, bearing immense significance. Current research highlights that nanoparticles offer superior efficacy and potential compared to conventional drug treatment and prevention methods. Notably, for drug delivery applications, it is imperative to utilize biodegradable nanoparticles. This paper reviews the structures and characteristics of various biodegradable nanoparticles and their applications in biomedicine in order to inspire more researchers to further explore the functions of nanoparticles. RNA plays a pivotal role in regulating the occurrence and progression of diseases, but its inherent susceptibility to degradation poses a challenge. In light of this, we conducted a comprehensive review of the research advancements concerning RNA-containing biodegradable nanoparticles in the realm of disease prevention and treatment, focusing on cancer, inflammatory diseases, and viral infections.

RAS signaling and immune cells: a sinister crosstalk in the tumor microenvironment

The rat sarcoma virus (RAS) gene is the most commonly mutated oncogene in cancer, with about 19% of cancer patients carrying RAS mutations. Studies on the interaction between RAS mutation and tumor immune microenvironment (TIM) have been flourishing in recent years. More and more evidence has proved that RAS signals regulate immune cells' recruitment, activation, and differentiation while assisting tumor cells to evade immune surveillance. This review concluded the direct and indirect treatment strategies for RAS mutations. In addition, we updated the underlying mechanisms by which RAS signaling modulated immune infiltration and immune escape. Finally, we discussed advances in RAS-targeted immunotherapies, including cancer vaccines and adoptive cell therapies, with a particular focus on combination strategies with personalized therapy and great potential to achieve lasting clinical benefits.

Treatment of Ulcerative Colitis by Cationic Liposome Delivered NLRP3 siRNA

Purpose

The abnormal activation of NLRP3 inflammasome is related to the occurrence and development of ulcerative colitis (UC). However, the ideal drug and delivery system remain important factors limiting the targeting of NLRP3 inflammasome in UC therapy. Gene therapy by delivering siRNA is effective in treating various diseases. Therefore, delivering siNLRP3 using an ideal vector for UC treatment is necessary.

Materials and Methods

Nanoparticles delivering siNLRP3 were developed based on cationic liposome (CLP/siNLRP3). Their ability to inhibit NLRP3 inflammasome activation was monitored using Western blot (WB) and Enzyme-linked Immunosorbent Assay (ELISA). The ASC oligomerization in LPS-primed peritoneal macrophages (PMs) was detected by WB and immunofluorescence. Moreover, we assessed the role of CLP/siNLRP3 on dextran sodium sulfate (DSS)-induced UC by examining NLRP3 levels, pro-inflammatory cytokines expression, and disease-associated index (DAI). Flow cytometry (FCM) was used to detect the contents of macrophages and T cells. Finally, we assessed the safety of CLP/siNLRP3.

Results

The prepared CLP was spherical, with a small particle size (94 nm) and low permeability. The CLP could efficiently protect siNLRP3 from degradation and then deliver siNLRP3 into PMs, inhibiting NLRP3 inflammasome activation. Also, the CLP/siNLRP3 could inhibit the secretion of mature IL-1β and IL-18 from PMs, thereby achieving a favorable anti-inflammation effect. In vivo, CLP/siNLRP3 could effectively alleviate intestinal injury in UC mice, which was attributed to down-regulating levels of IL-1β and IL-18, inhibiting infiltration of macrophages and other immune cells, and the polarization of M1 macrophages. Finally, pathological testing of tissue sections and blood biochemical tests showed no significant toxic effects of CLP/siNLRP3.

Conclusion

We introduced a prospective approach for the efficient delivery of siRNA in vitro and in vivo with high safety and stability, which was found to have great potential in treating NLRP3-driven diseases in an RNA-silencing manner.

Progress in circRNA-Targeted Therapy in Experimental Parkinson's Disease

Circular RNAs (circRNAs) are single-stranded RNA molecules often circularized by backsplicing. Growing evidence implicates circRNAs in the underlying mechanisms of various diseases, such as Alzheimer's and Parkinson's disease (PD)-the first and second most prevalent neurodegenerative disorders. In this sense, circSNCA, circHIPK2, circHIPK3, and circSLC8A1 are circRNAs that have been related to the neurodegenerative process of PD. Gain-of-function and loss-of-function studies on circRNAs have shed light on their roles in the pathobiology of various diseases. Gain-of-function approaches typically employ viral or non-viral vectors that hyperexpress RNA sequences capable of circularizing to form the specific circRNA under investigation. In contrast, loss-of-function studies utilize CRISPR/Cas systems, antisense oligonucleotides (ASOs), or RNAi techniques to knock down the target circRNA. The role of aberrantly expressed circRNAs in brain pathology has raised a critical question: could circRNAs serve as viable targets for neuroprotective treatments? Translating any oligonucleotide-based therapy, including those targeting circRNAs, involves developing adequate brain delivery systems, minimizing off-target effects, and addressing the high costs of treatment. Nonetheless, RNAi-based FDA-approved drugs have entered the market, and circRNAs have attracted significant attention and investment from major pharmaceutical companies. Spanning from bench to bedside, circRNAs present a vast opportunity in biotechnology for oligonucleotide-based therapies designed to slow or even halt the progression of neurodegenerative diseases.

Advances in MicroRNA Therapy for Heart Failure: Clinical Trials, Preclinical Studies, and Controversies

Heart failure (HF) is a rapidly growing public health issue with more than 37.7 million patients worldwide and an annual healthcare cost of $108 billion. However, HF-related drugs have not changed significantly for decades, and it is essential to find biological drugs to provide better treatment for HF patients. MicroRNAs (miRNAs) are non-coding RNAs (ncRNAs) with a length of approximately 21 nucleotides and play an important role in the onset and progression of cardiovascular diseases. Increasing studies have shown that miRNAs are widely involved in the pathophysiology of HF, and the regulation of miRNAs has promising therapeutic effects. Among them, there is great interest in miRNA-132, since the encouraging success of anti-miRNA-132 therapy in a phase 1b clinical trial in 2020. However, it is worth noting that the multi-target effect of miRNA may produce side effects such as thrombocytopenia, revascularization dysfunction, severe immune response, and even death. Advances in drug delivery modalities, delivery vehicles, chemical modifications, and plant-derived miRNAs are expected to address safety concerns and further improve miRNA therapy. Here, we reviewed the preclinical studies and clinical trials of HF-related miRNAs (especially miRNA-132) in the past 5 years and summarized the controversies of miRNA therapy.

Post-transcriptional control of haemostatic genes: mechanisms and emerging therapeutic concepts in thrombo-inflammatory disorders

The haemostatic system is pivotal to maintaining vascular integrity. Multiple components involved in blood coagulation have central functions in inflammation and immunity. A derailed haemostasis is common in prevalent pathologies such as sepsis, cardiovascular disorders, and lately, COVID-19. Physiological mechanisms limit the deleterious consequences of a hyperactivated haemostatic system through adaptive changes in gene expression. While this is mainly regulated at the level of transcription, co- and posttranscriptional mechanisms are increasingly perceived as central hubs governing multiple facets of the haemostatic system. This layer of regulation modulates the biogenesis of haemostatic components, for example in situations of increased turnover and demand. However, they can also be 'hijacked' in disease processes, thereby perpetuating and even causally entertaining associated pathologies. This review summarizes examples and emerging concepts that illustrate the importance of posttranscriptional mechanisms in haemostatic control and crosstalk with the immune system. It also discusses how such regulatory principles can be used to usher in new therapeutic concepts to combat global medical threats such as sepsis or cardiovascular disorders.

MicroRNAs-Based Theranostics against Anesthetic-Induced Neurotoxicity

Various clinical reports indicate prolonged exposure to general anesthetic-induced neurotoxicity (in vitro and in vivo). Behavior changes (memory and cognition) are compilations commonly cited with general anesthetics. The ability of miRNAs to modulate gene expression, thereby selectively altering cellular functions, remains one of the emerging techniques in the recent decade. Importantly, engineered miRNAs (which are of the two categories, i.e., agomir and antagomir) to an extent found to mitigate neurotoxicity. Utilizing pre-designed synthetic miRNA oligos would be an ideal analeptic approach for intervention based on indicative parameters. This review demonstrates engineered miRNA's potential as prophylactics and/or therapeutics minimizing the general anesthetics-induced neurotoxicity. Furthermore, we share our thoughts regarding the current challenges and feasibility of using miRNAs as therapeutic agents to counteract the adverse neurological effects. Moreover, we discuss the scientific status and updates on the novel neuro-miRNAs related to therapy against neurotoxicity induced by amyloid beta (Aβ) and Parkinson's disease (PD).

Application of nanotechnology in reversing therapeutic resistance and controlling metastasis of colorectal cancer

Colorectal cancer (CRC) is the most common digestive malignancy across the world. Its first-line treatments applied in the routine clinical setting include surgery, chemotherapy, radiotherapy, targeted therapy, and immunotherapy. However, resistance to therapy has been identified as the major clinical challenge that fails the treatment method, leading to recurrence and distant metastasis. An increasing number of studies have been attempting to explore the underlying mechanisms of the resistance of CRC cells to different therapies, which can be summarized into two aspects: (1) The intrinsic characters and adapted alterations of CRC cells before and during treatment that regulate the drug metabolism, drug transport, drug target, and the activation of signaling pathways; and (2) the suppressive features of the tumor microenvironment (TME). To combat the issue of therapeutic resistance, effective strategies are warranted with a focus on the restoration of CRC cells’ sensitivity to specific treatments as well as reprogramming impressive TME into stimulatory conditions. To date, nanotechnology seems promising with scope for improvement of drug mobility, treatment efficacy, and reduction of systemic toxicity. The instinctive advantages offered by nanomaterials enable the diversity of loading cargoes to increase drug concentration and targeting specificity, as well as offer a platform for trying the combination of different treatments to eventually prevent tumor recurrence, metastasis, and reversion of therapy resistance. The present review intends to summarize the known mechanisms of CRC resistance to chemotherapy, radiotherapy, immunotherapy, and targeted therapy, as well as the process of metastasis. We have also emphasized the recent application of nanomaterials in combating therapeutic resistance and preventing metastasis either by combining with other treatment approaches or alone. In summary, nanomedicine is an emerging technology with potential for CRC treatment; hence, efforts should be devoted to targeting cancer cells for the restoration of therapeutic sensitivity as well as reprogramming the TME. It is believed that the combined strategy will be beneficial to achieve synergistic outcomes contributing to control and management of CRC in the future.

Rational polyelectrolyte nanoparticles endow preosteoclast-targeted siRNA transfection for anabolic therapy of osteoporosis

Targeted transfection of siRNA to preosteoclasts features the potential of anti-osteoporosis, yet challenge arises from the development of satisfied delivery vehicles. Here, we design a rational core-shell nanoparticle (NP) composed of cationic and responsive core for controlled load and release of small interfering RNA (siRNA) and compatible polyethylene glycol shell modified with alendronate for enhanced circulation and bone-targeted delivery of siRNA. The designed NPs perform well on transfection of an active siRNA (siDcstamp) that interferes Dcstamp mRNA expression, leading to impeded preosteoclast fusion and bone resorption, as well as promoted osteogenesis. In vivo results corroborate the abundant siDcstamp accumulation on bone surfaces and the enhanced trabecular bone mass volume and microstructure in treating osteoporotic OVX mice by rebalancing bone resorption, formation, and vascularization. Our study validates the hypothesis that satisfied transfection of siRNA enables preserved preosteoclasts that regulate bone resorption and formation simultaneously as potential anabolic treatment for osteoporosis.

Inhibition of Chikungunya virus genome replication by targeting essential RNA structures within the virus genome

Chikungunya virus (CHIKV) is a pathogenic arbovirus spread by Aedes spp. mosquitos. CHIKV has a wide global prevalence and represents a significant health burden in affected populations. Symptoms of CHIKV infection include fever, rashes and debilitating joint and muscle pain, which can persist for several months to years in some patients. To date, there remains no vaccine or specific antiviral therapy against this important human pathogen. Based on our previously published structural and phenotypic analysis of the 5' region of the CHIKV genome, we designed a panel of locked nucleic acid oligonucleotides to bind structured RNA replication elements within the virus genome, which are essential for efficient CHIKV replication. Using electromobility shift assays, we confirmed the relative binding efficiencies of each LNA to target CHIKV genomic RNA. We then went on to demonstrate, using both sub-genomic replicon and infectious virus systems, that targeting individual RNA replication elements inhibits CHIKV genome replication and production of infectious virus. Time course assays demonstrated that LNAs can access the CHIKV replication complex and virus genome, during active virus replication. For the first time, these findings show that functional RNA elements can be specifically targeted during the CHIKV lifecycle and consequently represent potential novel antiviral targets.

Research Status and Prospect of Non-Viral Vectors Based on siRNA: A Review

Gene therapy has attracted much attention because of its unique mechanism of action, non-toxicity, and good tolerance, which can kill cancer cells without damaging healthy tissues. siRNA-based gene therapy can downregulate, enhance, or correct gene expression by introducing some nucleic acid into patient tissues. Routine treatment of hemophilia requires frequent intravenous injections of missing clotting protein. The high cost of combined therapy causes most patients to lack the best treatment resources. siRNA therapy has the potential of lasting treatment and even curing diseases. Compared with traditional surgery and chemotherapy, siRNA has fewer side effects and less damage to normal cells. The available therapies for degenerative diseases can only alleviate the symptoms of patients, while siRNA therapy drugs can upregulate gene expression, modify epigenetic changes, and stop the disease. In addition, siRNA also plays an important role in cardiovascular diseases, gastrointestinal diseases, and hepatitis B. However, free siRNA is easily degraded by nuclease and has a short half-life in the blood. Research has found that siRNA can be delivered to specific cells through appropriate vector selection and design to improve the therapeutic effect. The application of viral vectors is limited because of their high immunogenicity and low capacity, while non-viral vectors are widely used because of their low immunogenicity, low production cost, and high safety. This paper reviews the common non-viral vectors in recent years and introduces their advantages and disadvantages, as well as the latest application examples.

In silico prediction of siRNA ionizable-lipid nanoparticles In vivo efficacy: Machine learning modeling based on formulation and molecular descriptors

In silico prediction of the in vivo efficacy of siRNA ionizable-lipid nanoparticles is desirable as it can save time and resources dedicated to wet-lab experimentation. This study aims to computationally predict siRNA nanoparticles in vivo efficacy. A data set containing 120 entries was prepared by combining molecular descriptors of the ionizable lipids together with two nanoparticles formulation characteristics. Input descriptor combinations were selected by an evolutionary algorithm. Artificial neural networks, support vector machines and partial least squares regression were used for QSAR modeling. Depending on how the data set is split, two training sets and two external validation sets were prepared. Training and validation sets contained 90 and 30 entries respectively. The results showed the successful predictions of validation set log (siRNA dose) with R_val ²= 0.86-0.89 and 0.75-80 for validation sets one and two, respectively. Artificial neural networks resulted in the best R_val ² for both validation sets. For predictions that have high bias, improvement of R_val ² from 0.47 to 0.96 was achieved by selecting the training set lipids lying within the applicability domain. In conclusion, in vivo performance of siRNA nanoparticles was successfully predicted by combining cheminformatics with machine learning techniques.

Nanomedicine and drug delivery to the retina: current status and implications for gene therapy

Blindness affects more than 60 million people worldwide. Retinal disorders, including age-related macular degeneration (AMD), diabetic retinopathy (DR), and glaucoma, are the leading causes of blindness. Finding means to optimize local and sustained delivery of drugs or genes to the eye and retina is one goal to advance the development of new therapeutics. Despite the ease of accessibility of delivering drugs via the ocular surface, the delivery of drugs to the retina is still challenging due to anatomic and physiologic barriers. Designing a suitable delivery platform to overcome these barriers should enhance drug bioavailability and provide a safe, controlled, and sustained release. Current inventions for posterior segment treatments include intravitreal implants and subretinal viral gene delivery that satisfy these criteria. Several other novel drug delivery technologies, including nanoparticles, micelles, dendrimers, microneedles, liposomes, and nanowires, are now being widely studied for posterior segment drug delivery, and extensive research on gene delivery using siRNA, mRNA, or aptamers is also on the rise. This review discusses the current state of retinal drug/gene delivery and highlights future therapeutic opportunities.

Modulation of Monocyte Response by Microrna-15b/106a/374a During Antibody-mediated Rejection in Kidney Transplantation

BACKGROUND

Increasing evidence suggest that microRNAs are involved in the physiopathology of acute or chronic renal disease. In kidney transplantation, as key regulators of cellular homeostasis, microRNAs may be involved in the regulation of immune cell function and the allograft response. Here, we investigated the change in circulating microRNA expression profile and their involvement in the profound transcriptional changes associated with antibody-mediated rejection (ABMR).

METHODS

Blood samples were collected at the time of the 710 kidney allograft biopsies at 4 European transplant centers. Messenger RNA and microRNA profiling analyses were performed in a discovery-to-validation study within 3 independent cohorts encompassing N = 126, N = 135, and N = 416 patients, respectively.

RESULTS

Compared with samples with no ABMR, 14 microRNAs were significantly decreased in ABMR samples. Among them, expression levels of microRNA-15b, microRNA-106a, and microRNA-374a gradually decreased with the severity of ABMR lesions. From their in silico-predicted target genes, a high proportion proved to be significantly upregulated in the paired transcriptomic analysis. Gene ontology analyses of microRNA-15b/-106a/-374a suggested enrichment in myeloid-related pathways, which was further refined by in silico and ex vivo transcriptomic analyses, showing a specific origin from classical CD14 + monocytes. Finally, human CD14 + monocytes were subjected to transduction by antago-microRNAs to mimic ABMR pathology. MicroRNA-15b/-106a/-374a impairment resulted in cellular activation with an increased expression of CD69, CRIM1, IPO7, and CAAP1, direct and common targets of the 3 microRNAs.

CONCLUSIONS

Together, our data provide new insights into circulating microRNAs as markers and key players in ABMR, and they suggest monocyte involvement in this process.

Antibody-Functionalized Nanoformulations for Targeted Therapy of Colorectal Cancer: A Systematic Review

The failure of chemotherapeutic treatment in colorectal cancer (CRC), the second most mortal cancer worldwide, is associated with several drug limitations, such as non-selective distribution, short half-life, and development of multiple resistances. One of the most promising strategies in CRC therapy is the development of delivery systems based on nanomaterials that can transport antitumor agents to the tumor site more efficiently, increasing accumulation within the tumor and thus the antitumor effect. In addition to taking advantage of the increased permeability and retention effect (EPR) of solid tumors, these nanoformulations can be conjugated with monoclonal antibodies that recognize molecular markers that are specifically over-expressed on CRC cells. Active targeting of nanoformulations reduces the adverse effects associated with the cytotoxic activity of drugs in healthy tissues, which will be of interest for improving the quality of life of cancer patients in the future. This review focuses on in vitro and in vivo studies of drug delivery nanoformulations functionalized with monoclonal antibodies for targeted therapy of CRC.

Cell cycle associated miRNAs as target and therapeutics in lung cancer treatment

Lung cancer is the primary cause of cancer related deaths worldwide. Limited therapeutic options and resistance to existing drugs are the major hindrances to the clinical success of this cancer. In the past decade, several studies showed the role of microRNA (miRNA) driven cell cycle regulation in lung cancer progression. Therefore, these small nucleotide molecules could be utilized as promising tools in lung cancer therapy. In this review, we highlighted the recent advancements in lung cancer therapy using cell cycle linked miRNAs. By highlighting the roles of the specific cell cycle core regulators affiliated miRNAs in lung cancer, we further outlined how these miRNAs can be explored in early diagnosis and treatment strategies to prevent lung cancer. With the provided information from our review, more medical efforts can ensure a potential breakthrough in miRNA-based lung cancer therapy.

Therapeutic Targeting of Overexpressed MiRNAs in Cancer Progression

MicroRNAs (miRNAs) are non-coding RNAs involved in the modulation of various biological processes, and their dysregulation is greatly associated with cancer progression as miRNAs can act as either tumour suppressors or oncogenes, depending on their intended target, mechanism of actions, and expression levels. This review paper aims to shed light on the role of overexpressed miRNAs in cancer progression. Cancer cells are known to upregulate specific miRNAs to inhibit the expression of genes regulating the cell cycle, such as PTEN, FOXO1, SOX7, caspases, KLF4, TRIM8, and ZBTB4. Inhibition of these genes promotes cancer development and survival by inducing cell growth, migration, and invasion while evading apoptosis, which leads to poor cancer survival rates. Therefore, the potential of antisense miRNAs in treating cancer is also explored in this review. Antisense miRNAs are chemically modified oligonucleotides that can reverse the action of overexpressed miRNAs. Currently, the therapeutic potential of antisense miRNAs is being validated in both in vitro and in vivo models. Studies have shown that antisense miRNAs could slow down the progression of cancer while enhancing the action of conventional anticancer drugs. These findings provide hope for future oncologic care as this novel intervention is in the process of clinical translation.

Non-Coding RNAs in Hepatocellular Carcinoma

Liver cancer ranks as the fourth leading cause of cancer-related deaths. Despite extensive research efforts aiming to evaluate the biological mechanisms underlying hepatocellular carcinoma (HCC) development, little has been translated towards new diagnostic and treatment options for HCC patients. Historically, the focus has been centered on coding RNAs and their respective proteins. However, significant advances in sequencing and RNA detection technologies have shifted the research focus towards non-coding RNAs (ncRNA), as well as their impact on HCC development and progression. A number of studies reported complex post-transcriptional interactions between various ncRNA and coding RNA molecules. These interactions offer insights into the role of ncRNAs in both the known pathways leading to oncogenesis, such as dysregulation of p53, and lesser-known mechanisms, such as small nucleolar RNA methylation. Studies investigating these mechanisms have identified prevalent ncRNA changes in microRNAs, snoRNAs, and long non-coding RNAs that can both pre- and post-translationally regulate key factors in HCC progression. In this review, we present relevant publications describing ncRNAs to summarize the impact of different ncRNA species on liver cancer development and progression and to evaluate recent attempts at clinical translation.

RNA-based therapeutics: an overview and prospectus

The growing understanding of RNA functions and their crucial roles in diseases promotes the application of various RNAs to selectively function on hitherto "undruggable" proteins, transcripts and genes, thus potentially broadening the therapeutic targets. Several RNA-based medications have been approved for clinical use, while others are still under investigation or preclinical trials. Various techniques have been explored to promote RNA intracellular trafficking and metabolic stability, despite significant challenges in developing RNA-based therapeutics. In this review, the mechanisms of action, challenges, solutions, and clinical application of RNA-based therapeutics have been comprehensively summarized.

R4 RGS proteins as fine tuners of immature and mature hematopoietic cell trafficking

G-protein-coupled receptors (GPCRs) are the largest and most diverse group of membrane receptors. They are involved in almost every physiologic process and consequently have a pivotal role in an extensive number of pathologies, including genetic, neurologic, and immune system disorders. Indeed, the vast array of GPCRs mechanisms have led to the development of a tremendous number of drug therapies and already account for about a third of marketed drugs. These receptors mediate their downstream signals primarily via G proteins. The regulators of G-protein signaling (RGS) proteins are now in the spotlight as the critical modulatory factors of active GTP-bound Gα subunits of heterotrimeric G proteins to fine-tune the biologic responses driven by the GPCRs. Also, they possess noncanonical functions by multiple mechanisms, such as protein-protein interactions. Essential roles and impacts of these RGS proteins have been revealed in physiology, including hematopoiesis and immunity, and pathologies, including asthma, cancers, and neurologic disorders. This review focuses on the largest subfamily of R4 RGS proteins and provides a brief overview of their structures and G-proteins selectivity. With particular interest, we explore and highlight, their expression in the hematopoietic system and the regulation in the engraftment of hematopoietic stem/progenitor cells (HSPCs). Distinct expression patterns of R4 RGS proteins in the hematopoietic system and their pivotal roles in stem cell trafficking pave the way for realizing new strategies for enhancing the clinical performance of hematopoietic stem cell transplantation. Finally, we discuss the exciting future trends in drug development by targeting RGS activity and expression with small molecules inhibitors and miRNA approaches.

Spotlight on Givosiran as a Treatment Option for Adults with Acute Hepatic Porphyria: Design, Development, and Place in Therapy

Small interfering ribonucleic acids [siRNAs] are short ribonucleic acid (RNA) fragments cleaved from double-stranded RNA molecules that target and bind to specific sequences on messenger RNA (mRNA), leading to their destruction. Therefore, the siRNA down-regulates the formation of selected mRNAs and their protein products. Givosiran is one such siRNA that uses this mechanism to treat acute hepatic porphyrias. Acute hepatic porphyrias are a group of rare, inherited metabolic disorders, characterized by acute potentially life-threatening attacks as well as chronic symptoms with a negative impact on quality of life. It has four types, each associated with distinct enzyme defects in the heme biosynthesis pathway in the liver. By targeting the expression of hepatic 5-aminolevulinic acid [ALA] synthase-1 [ALAS1], givosiran can down-regulate levels of toxic metabolites, leading to biochemical and clinical improvement. Givosiran selectively targets hepatocytes due to its linkage to N-acetylgalactosamine (GalNac) leading to its selective uptake via asialoglycoprotein receptors (ASGPR). We provide an up-to-date literature review regarding givosiran in the context of a clinical overview of the porphyrias, an overview of siRNAs for therapy of human disorders, the design and development of givosiran, key clinical trial results of givosiran for prevention of acute porphyric attacks, emerging concerns regarding chronic use of givosiran, and the overall management of acute hepatic porphyrias. These insights are important not only for the management of acute hepatic porphyrias but also for the emerging field of siRNAs and their role in novel therapies for various diseases.

Histone Modifications and Non-Coding RNAs: Mutual Epigenetic Regulation and Role in Pathogenesis

In the last few years, more and more scientists have suggested and confirmed that epigenetic regulators are tightly connected and form a comprehensive network of regulatory pathways and feedback loops. This is particularly interesting for a better understanding of processes that occur in the development and progression of various diseases. Appearing on the preclinical stages of diseases, epigenetic aberrations may be prominent biomarkers. Being dynamic and reversible, epigenetic modifications could become targets for a novel option for therapy. Therefore, in this review, we are focusing on histone modifications and ncRNAs, their mutual regulation, role in cellular processes and potential clinical application.

Can pulmonary RNA delivery improve our pandemic preparedness?

The coronavirus pandemic has changed our perception of RNA medicines, and RNA vaccines have revolutionized our pandemic preparedness. But are we indeed prepared for the next variant or the next emerging virus? How can we prepare? And what does the role of inhaled antiviral RNA play in this regard? When the pandemic started, I rerouted much of the ongoing inhaled RNA delivery research in my group towards the inhibition and treatment of respiratory viral infections. Two years later, I have taken the literature, past and ongoing clinical trials into consideration and have gained new insights based on our collaborative research which I will discuss in this oration.

Microfluidic fabrication of lipid nanoparticles for the delivery of nucleic acids

Gene therapy has emerged as a potential platform for treating several dreaded and rare diseases that would not have been possible with traditional therapies. Viral vectors have been widely explored as a key platform for gene therapy due to their ability to efficiently transport nucleic acid-based therapeutics into the cells. However, the lack of precision in their delivery has led to several off-target toxicities. As such, various strategies in the form of non-viral gene delivery vehicles have been explored and are currenlty employed in several therapies including the SARS-CoV-2 vaccine. In this review, we discuss the opportunities lipid nanoparticles (LNPs) present for efficient gene delivery. We also discuss various synthesis strategies via microfluidics for high throughput fabrication of non-viral gene delivery vehicles. We conclude with the recent applications and clinical trials of these vehicles for the delivery of different genetic materials such as CRISPR editors and RNA for different medical conditions ranging from cancer to rare diseases.

Identification of 4-anilino-quin(az)oline as a cell active Protein Kinase Novel 3 (PKN3) inhibitor chemotype

Deep annotation of a library of 4-anilinoquinolines led to the identification of 7-iodo- N -(3,4,5-trimethoxyphenyl)quinolin-4-amine 16 as a potent inhibitor (IC 50 = 14 nM) of Protein Kinase Novel 3 (PKN3) with micromolar activity in cells. Compound 16 is a potential tool compound to study the cell biology of PKN3 and its role in pancreatic and prostate cancer and T-cell acute lymphoblastic leukemia. These 4-anilinoquinolines may also be useful tools to uncover the therapeutic potential of PKN3 inhibition in a broad range of diseases.

Advances in siRNA therapeutics and synergistic effect on siRNA activity using emerging dual ribose modifications

Nucleic acid-based therapeutics that control gene expression have been steadily progressing towards achieving their full clinical potential throughout the last few decades. Rapid progress has been achieved in RNAi-based therapy by optimizing high specificity and gene silencing efficiency using chemically modified siRNAs. Since 2018, four siRNA drugs – patisiran, givosiran, lumasiran, and inclisiran, were approved by the US FDA, providing a testament to the promise of RNAi therapeutics. Despite these promising results, safe and efficient siRNA delivery at the target site remains a major obstacle for efficient siRNA-based therapeutics. In this review, we have outlined the synergistic effects of emerging dual ribose modifications, including 2’,4’- and 2’,5’-modifications, 5’-E/Z-vinylphosphonate, and northern methanocarbacyclic (NMC) modifications that have contributed to drug-like effects in siRNA. These modifications enhance nuclease stability, prolong gene silencing efficiency, improve thermal stability, and exhibit high tissue accumulation. We also highlight the current progress in siRNA clinical trials. This review will help to understand the potential effects of dual ribose modifications and provides alternative ways to use extensive 2’-modifications in siRNA drugs. Moreover, the minimal number of these dual ribose modifications could be sufficient to achieve the desired therapeutic effect. In future, detailed in vivo studies using these dual ribose modifications could help to improve the therapeutic effects of siRNA. Rational design could further open doors for the rapid progress in siRNA therapeutics.

Preclinical Safety Assessment of Therapeutic Oligonucleotides

During the last decade, therapeutic oligonucleotide drugs (OND) have witnessed a tremendous development in chemistry and mechanistic understanding that have translated into successful clinical applications. Depending on the specific OND mechanism, chemistry, and design, the DMPK and toxicity properties can vary significantly between different OND classes and delivery approaches, the latter including lipid formulations or conjugation approaches to enhance productive OND uptake. At the same time, with the only difference between compounds being the nucleobase sequence, ONDs with same mechanism of action, chemistry, and design show relatively consistent behavior, allowing certain extrapolations between compounds within an OND class. This chapter provides a summary of the most common toxicities, the improved mechanistic understanding and the safety assessment activities performed for therapeutic oligonucleotides during the drug discovery and development process. Several of the considerations described for therapeutic applications should also be of value for the scientists mainly using oligonucleotides as research tools to explore various biological processes.

RNAi-based therapeutics and tumor targeted delivery in cancer

Over the past decade, non-coding RNA-based therapeutics have proven as a great potential for the development of targeted therapies for cancer and other diseases. The discovery of the critical function of microRNAs (miRNAs) has generated great excitement in developing miRNA-based therapies. The dysregulation of miRNAs contributes to the pathogenesis of various human diseases and cancers by modulating genes that are involved in critical cellular processes, including cell proliferation, differentiation, apoptosis, angiogenesis, metastasis, drug resistance, and tumorigenesis. miRNA (miRNA mimic, anti-miRNA/antagomir) and small interfering RNA (siRNA) can inhibit the expression of any cancer-related genes/mRNAs with high specificity through RNA interference (RNAi), thus representing a remarkable therapeutic tool for targeted therapies and precision medicine. siRNA and miRNA-based therapies have entered clinical trials and recently three novel siRNA-based therapeutics were approved by the Food and Drug Administration (FDA), indicating the beginning of a new era of targeted therapeutics. The successful clinical applications of miRNA and siRNA therapeutics rely on safe and effective nanodelivery strategies for targeting tumor cells or tumor microenvironment. For this purpose, promising nanodelivery/nanoparticle-based approaches have been developed using a variety of molecules for systemic administration and improved tumor targeted delivery with reduced side effects. In this review, we present an overview of RNAi-based therapeutics, the major pharmaceutical challenges, and the perspectives for the development of promising delivery systems for clinical translation. We also highlight the passive and active tumor targeting nanodelivery strategies and primarily focus on the current applications of nanoparticle-based delivery formulations for tumor targeted RNAi molecules and their recent advances in clinical trials in human cancers.

The Optimized Delivery of Triterpenes by Liposomal Nanoformulations: Overcoming the Challenges

The last decade has witnessed a sustained increase in the research development of modern-day chemo-therapeutics, especially for those used for high mortality rate pathologies. However, the therapeutic landscape is continuously changing as a result of the currently existing toxic side effects induced by a substantial range of drug classes. One growing research direction driven to mitigate such inconveniences has converged towards the study of natural molecules for their promising therapeutic potential. Triterpenes are one such class of compounds, intensively investigated for their therapeutic versatility. Although the pharmacological effects reported for several representatives of this class has come as a well-deserved encouragement, the pharmacokinetic profile of these molecules has turned out to be an unwelcomed disappointment. Nevertheless, the light at the end of the tunnel arrived with the development of nanotechnology, more specifically, the use of liposomes as drug delivery systems. Liposomes are easily synthesizable phospholipid-based vesicles, with highly tunable surfaces, that have the ability to transport both hydrophilic and lipophilic structures ensuring superior drug bioavailability at the action site as well as an increased selectivity. This study aims to report the results related to the development of different types of liposomes, used as targeted vectors for the delivery of various triterpenes of high pharmacological interest.

Catabolism of Hydroxyproline in Vertebrates: Physiology, Evolution, Genetic Diseases and New siRNA Approach for Treatment

Hydroxyproline is one of the most prevalent amino acids in animal proteins. It is not a genetically encoded amino acid, but, rather, it is produced by the post-translational modification of proline in collagen, and a few other proteins, by prolyl hydroxylase enzymes. Although this post-translational modification occurs in a limited number of proteins, its biological significance cannot be overestimated. Considering that hydroxyproline cannot be re-incorporated into pro-collagen during translation, it should be catabolized following protein degradation. A cascade of reactions leads to production of two deleterious intermediates: glyoxylate and hydrogen peroxide, which need to be immediately converted. As a result, the enzymes involved in hydroxyproline catabolism are located in specific compartments: mitochondria and peroxisomes. The particular distribution of catabolic enzymes in these compartments, in different species, depends on their dietary habits. Disturbances in hydroxyproline catabolism, due to genetic aberrations, may lead to a severe disease (primary hyperoxaluria), which often impairs kidney function. The basis of this condition is accumulation of glyoxylate and its conversion to oxalate. Since calcium oxalate is insoluble, children with this rare inherited disorder suffer from progressive kidney damage. This condition has been nearly incurable until recently, as significant advances in substrate reduction therapy using small interference RNA led to a breakthrough in primary hyperoxaluria type 1 treatment.

Targeting the undruggable oncogenic KRAS: the dawn of hope

KRAS mutations are the drivers of various cancers, including non-small cell lung cancer, colon cancer, and pancreatic cancer. Over the last 30 years, immense efforts have been made to inhibit KRAS mutants and oncogenic KRAS signaling using inhibitors. Recently, specific targeting of KRAS mutants with small molecules revived the hopes for successful therapies for lung, pancreatic, and colorectal cancer patients. Moreover, advances in gene editing, protein engineering, and drug delivery formulations have revolutionized cancer therapy regimens. New therapies aim to improve immune surveillance and enhance antitumor immunity by precisely targeting cancer cells harboring oncogenic KRAS. Here, we review recent KRAS-targeting strategies, their therapeutic potential, and remaining challenges to overcome. We also highlight the potential synergistic effects of various combinatorial therapies in preclinical and clinical trials.

Delivery of therapeutic oligonucleotides in nanoscale

Therapeutic oligonucleotides (TOs) represent one of the most promising drug candidates in the targeted cancer treatment due to their high specificity and capability of modulating cellular pathways that are not readily druggable. However, efficiently delivering of TOs to cancer cellular targets is still the biggest challenge in promoting their clinical translations. Emerging as a significant drug delivery vector, nanoparticles (NPs) can not only protect TOs from nuclease degradation and enhance their tumor accumulation, but also can improve the cell uptake efficiency of TOs as well as the following endosomal escape to increase the therapeutic index. Furthermore, targeted and on-demand drug release of TOs can also be approached to minimize the risk of toxicity towards normal tissues using stimuli-responsive NPs. In the past decades, remarkable progresses have been made on the TOs delivery based on various NPs with specific purposes. In this review, we will first give a brief introduction on the basis of TOs as well as the action mechanisms of several typical TOs, and then describe the obstacles that prevent the clinical translation of TOs, followed by a comprehensive overview of the recent progresses on TOs delivery based on several various types of nanocarriers containing lipid-based nanoparticles, polymeric nanoparticles, gold nanoparticles, porous nanoparticles, DNA/RNA nanoassembly, extracellular vesicles, and imaging-guided drug delivery nanoparticles.

The Value of Circulating Circular RNA in Cancer Diagnosis, Monitoring, Prognosis, and Guiding Treatment

Liquid biopsy includes non-invasive analysis of circulating tumor-derived substances. It is a novel, innovative cancer screening tool that overcomes the limitations of current invasive tissue examinations in precision oncology. Circular RNA (circRNA) is a recent, novel, and attractive liquid biomarker showing stability, abundance, and high specificity in various diseases, especially in human cancers. This review focused on the emerging potential of human circRNA in body fluids as the liquid biopsy biomarkers for cancers and the methods used to detect the circRNA expression and summarized the construction of circRNA biomarkers in body fluids for treating human cancers and their limitations before they become part of routine clinical medicine. Furthermore, the future opportunities and challenges of translating circRNAs in liquid biopsy into clinical practices were explored.

microRNA-based diagnostic and therapeutic applications in cancer medicine

It has been almost two decades since the first link between microRNAs and cancer was established. In the ensuing years, this abundant class of short noncoding regulatory RNAs has been studied in virtually all cancer types. This tremendously large body of research has generated innovative technological advances for detection of microRNAs in tissue and bodily fluids, identified the diagnostic, prognostic, and/or predictive value of individual microRNAs or microRNA signatures as potential biomarkers for patient management, shed light on regulatory mechanisms of RNA-RNA interactions that modulate gene expression, uncovered cell-autonomous and cell-to-cell communication roles of specific microRNAs, and developed a battery of viral and nonviral delivery approaches for therapeutic intervention. Despite these intense and prolific research efforts in preclinical and clinical settings, there are a limited number of microRNA-based applications that have been incorporated into clinical practice. We review recent literature and ongoing clinical trials that highlight most promising approaches and standing challenges to translate these findings into viable microRNA-based clinical tools for cancer medicine. This article is categorized under: RNA in Disease and Development > RNA in Disease.

Carbon Dioxide-Derived Biodegradable and Cationic Polycarbonates as a New siRNA Carrier for Gene Therapy in Pancreatic Cancer

Pancreatic cancer is an aggressive malignancy associated with poor prognosis and a high tendency in developing infiltration and metastasis. K-ras mutation is a major genetic disorder in pancreatic cancer patient. RNAi-based therapies can be employed for combating pancreatic cancer by silencing K-ras gene expression. However, the clinical application of RNAi technology is appreciably limited by the lack of a proper siRNA delivery system. To tackle this hurdle, cationic poly (cyclohexene carbonate) s (CPCHCs) using widely sourced CO₂ as the monomer are subtly synthesized via ring-opening copolymerization (ROCOP) and thiol-ene functionalization. The developed CPCHCs could effectively encapsulate therapeutic siRNA to form CPCHC/siRNA nanoplexes (NPs). Serving as a siRNA carrier, CPCHC possesses biodegradability, negligible cytotoxicity, and high transfection efficiency. In vitro study shows that CPCHCs are capable of effectively protecting siRNA from being degraded by RNase and promoting a sustained endosomal escape of siRNA. After treatment with CPCHC/siRNA NPs, the K-ras gene expression in both pancreatic cancer cell line (PANC-1 and MiaPaCa-2) are significantly down-regulated. Subsequently, the cell growth and migration are considerably inhibited, and the treated cells are induced into cell apoptotic program. These results demonstrate the promising potential of CPCHC-mediated siRNA therapies in pancreatic cancer treatment.

Effects of intravitreal injection of siRNA against caspase-2 on retinal and optic nerve degeneration in air blast induced ocular trauma

Ocular repeated air blast injuries occur from low overpressure blast wave exposure, which are often repeated and in quick succession. We have shown that caspase-2 caused the death of retinal ganglion cells (RGC) after blunt ocular trauma. Here, we investigated if caspase-2 also mediates RGC apoptosis in a mouse model of air blast induced indirect traumatic optic neuropathy (b-ITON). C57BL/6 mice were exposed to repeated blasts of overpressure air (3 × 2 × 15 psi) and intravitreal injections of siRNA against caspase-2 (siCASP2) or against a control enhanced green fluorescent protein (siEGFP) at either 5 h after the first 2 × 15 psi ("post-blast") or 48 h before the first blast exposure ("pre-blast") and repeated every 7 days. RGC counts were unaffected by the b-ITON or intravitreal injections, despite increased degenerating ON axons, even in siCASP2 "post-blast" injection groups. Degenerating ON axons remained at sham levels after b-ITON and intravitreal siCASP2 "pre-blast" injections, but with less degenerating axons in siCASP2 compared to siEGFP-treated eyes. Intravitreal injections "post-blast" caused greater vitreous inflammation, potentiated by siCASP2, with less in "pre-blast" injected eyes, which was abrogated by siCASP2. We conclude that intravitreal injection timing after ocular trauma induced variable retinal and ON pathology, undermining our candidate neuroprotective therapy, siCASP2.

Effective tools for RNA-derived therapeutics: siRNA interference or miRNA mimicry

The approval of the first small interfering RNA (siRNA) drug Patisiran by FDA in 2018 marks a new era of RNA interference (RNAi) therapeutics. MicroRNAs (miRNA), an important post-transcriptional gene regulator, are also the subject of both basic research and clinical trials. Both siRNA and miRNA mimics are ~21 nucleotides RNA duplexes inducing mRNA silencing. Given the well performance of siRNA, researchers ask whether miRNA mimics are unnecessary or developed siRNA technology can pave the way for the emergence of miRNA mimic drugs. Through comprehensive comparison of siRNA and miRNA, we focus on (1) the common features and lessons learnt from the success of siRNAs; (2) the unique characteristics of miRNA that potentially offer additional therapeutic advantages and opportunities; (3) key areas of ongoing research that will contribute to clinical application of miRNA mimics. In conclusion, miRNA mimics have unique properties and advantages which cannot be fully matched by siRNA in clinical applications. MiRNAs are endogenous molecules and the gene silencing effects of miRNA mimics can be regulated or buffered to ameliorate or eliminate off-target effects. An in-depth understanding of the differences between siRNA and miRNA mimics will facilitate the development of miRNA mimic drugs.

Innovative lipoplexes formulations with enhanced siRNA efficacy for cancer treatment: Where are we now?

Over the past two decades, RNA interference has become an extensively studied mechanism to silence gene and treat diseases including cancer. siRNA appears as a promising strategy that could avoid some side effects related to traditional chemotherapy. Considering the weak stability of naked siRNA in blood, vectors like cationic liposomes or Lipid Nanoparticles (LNPs) are widely used to carry and protect siRNA until it reaches the tumor targeted. Despite extensive research, only three RNAi drugs are currently approved by the Food and Drug Administration, including only one LNP formulation of siRNA to treat hereditary ATTR amyloidosis. This shows the difficulty of lipoplexes clinical translation, in particular in cancer therapy. To overcome the lipoplexes limitations, searches are made on innovative lipoplexes formulations with enhanced siRNA efficacy. The present review is focusing on the recent use of pH-sensitive lipids, peptides and cell-penetrating peptides or polymers. The incorporation of some of these components in the lipoplex formulation induces a fusogenic property or an enhanced endosomal escape, an enhanced cellular uptake, an enhanced tumor targeting, an improved stability in the blood stream …These innovations appear critical to obtain an efficient siRNA accumulation in tumor cells with effective antitumor effect considering the complex tumor environment.

RNA Virus-Encoded miRNAs: Current Insights and Future Challenges

MicroRNAs are small non-coding RNAs that regulate eukaryotic gene expression at the post-transcriptional level and affect a wide range of biological processes. Over the past two decades, numerous virus-encoded miRNAs have been identified. Some of them are crucial for viral replication, whereas others can help immune evasion. Recent sequencing-based bioinformatics methods have helped identify many novel miRNAs, which are encoded by RNA viruses. Unlike the well-characterized DNA virus-encoded miRNAs, the role of RNA virus-encoded miRNAs remains controversial. In this review, we first describe the current knowledge of miRNAs encoded by various RNA viruses, including newly emerging viruses. Next, we discuss how RNA virus-encoded miRNAs might facilitate viral replication, immunoevasion, and persistence in their hosts. Last, we briefly discuss the challenges in the experimental methodologies and potential applications of miRNAs for diagnosis and therapeutics.