Pharmacokinetics and Proceedings in Clinical Application of Nucleic Acid Therapeutics

Potential Use of MicroRNA Technology in Thalassemia Therapy

Thalassemia encompasses a group of inherited hemoglobin disorders characterized by reduced or absent production of the α- or β-globin chains, leading to anemia and other complications. Current management relies on lifelong blood transfusions and iron chelation, which is burdensome for patients. This review summarizes the emerging therapeutic potential of modulating microRNAs (miRNAs) to treat thalassemia. MiRNAs are small non-coding RNAs that regulate gene expression through sequence-specific binding to messenger RNAs (mRNAs). While they commonly repress gene expression by binding to the 3' untranslated regions (UTRs) of target mRNAs, miRNAs can also interact with 5'UTRs and gene promoters to activate gene expression. Many miRNAs are now recognized as critical regulators of erythropoiesis and are abnormally expressed in β-thalassemia. Therapeutically restoring levels of deficient miRNAs or inhibiting overexpression through miRNA mimics or inhibitors (antagomir), respectively, has shown preclinical efficacy in ameliorating thalassemic phenotypes. The miR-144/451 cluster is especially compelling for targeted upregulation to reactivate fetal hemoglobin synthesis. Advances in delivery systems are addressing previous challenges in stability and targeting of miRNA-based drugs. While still early, gene therapy studies suggest combinatorial approaches with miRNA modulation may provide synergistic benefits. Several key considerations remain including enhancing delivery, minimizing off-target effects, and demonstrating long-term safety and efficacy. While no miRNA therapies have yet progressed to clinical testing for thalassemia specifically, important lessons are being learned through clinical trials for other diseases and conditions, such as cancer, cardiovascular diseases, and viral. If limitations can be overcome through multi-disciplinary collaboration, miRNAs hold great promise to expand and transform treatment options for thalassemia in the future by precisely targeting pathogenic molecular networks. Ongoing innovations, such as advancements in miRNA delivery systems, improved targeting mechanisms, and enhanced understanding of miRNA biology, continue to drive progress in this emerging field towards realizing the clinical potential of miRNA-based medicines for thalassemia patients.

Current status and trends in small nucleic acid drug development: Leading the future

Small nucleic acid drugs, composed of nucleotides, represent a novel class of pharmaceuticals that differ significantly from conventional small molecule and antibody-based therapeutics. These agents function by selectively targeting specific genes or their corresponding messenger RNAs (mRNAs), further modulating gene expression and regulating translation-related processes. Prominent examples within this category include antisense oligonucleotides (ASO), small interfering RNAs (siRNAs), microRNAs (miRNAs), and aptamers. The emergence of small nucleic acid drugs as a focal point in contemporary biopharmaceutical research is attributed to their remarkable specificity, facile design, abbreviated development cycles, expansive target spectrum, and prolonged activity. Overcoming challenges such as poor stability, immunogenicity, and permeability issues have been addressed through the integration of chemical modifications and the development of drug delivery systems. This review provides an overview of the current status and prospective trends in small nucleic acid drug development. Commencing with a historical context, we introduce the primary classifications and mechanisms of small nucleic acid drugs. Subsequently, we delve into the advantages of the U.S. Food and Drug Administration (FDA) approved drugs and mainly discuss the challenges encountered during their development. Apart from researching chemical modification and delivery system that efficiently deliver and enrich small nucleic acid drugs to target tissues, promoting endosomal escape is a critical scientific question and important research direction in siRNA drug development. Future directions in this field will prioritize addressing these challenges to facilitate the clinical transformation of small nucleic acid drugs.

Population pharmacokinetics of imetelstat, a first-in-class oligonucleotide telomerase inhibitor

Imetelstat is a novel, first-in-class, oligonucleotide telomerase inhibitor in development for the treatment of hematologic malignancies including lower-risk myelodysplastic syndromes and myelofibrosis. A nonlinear mixed-effects model was developed to characterize the population pharmacokinetics of imetelstat and identify and quantify covariates that contribute to its pharmacokinetic variability. The model was developed using plasma concentrations from 7 clinical studies including 424 patients with solid tumors or hematologic malignancies who received single-agent imetelstat via intravenous infusion at various dose levels (0.4-11.7 mg/kg) and schedules (every week to every 4 weeks). Covariate analysis included factors related to demographics, disease, laboratory results, renal and hepatic function, and antidrug antibodies. Imetelstat was described by a two-compartment, nonlinear disposition model with saturable binding/distribution and dose- and time-dependent elimination from the central compartment. Theory-based allometric scaling for body weight was included in disposition parameters. The final covariates included sex, time, malignancy, and dose on clearance; malignancy and sex on volume of the central compartment; and malignancy and spleen volume on concentration of target. Clearance in females was modestly lower, resulting in nonclinically relevant increases in predicted exposure relative to males. No effects on imetelstat pharmacokinetics were identified for mild-to-moderate hepatic or renal impairment, age, race, and antidrug antibody status. All model parameters were estimated with adequate precision (relative standard error < 29%). Visual predictive checks confirmed the capacity of the model to describe the data. The analysis supports the imetelstat body-weight-based dosing approach and lack of need for dose individualizations for imetelstat-treated patients.

A comparative analysis of peptide-delivered antisense antibiotics using diverse nucleotide mimics

Antisense oligomer (ASO)-based antibiotics that target mRNAs of essential bacterial genes have great potential for counteracting antimicrobial resistance and for precision microbiome editing. To date, the development of such antisense antibiotics has primarily focused on using phosphorodiamidate morpholino (PMO) and peptide nucleic acid (PNA) backbones, largely ignoring the growing number of chemical modalities that have spurred the success of ASO-based human therapy. Here, we directly compare the activities of seven chemically distinct 10mer ASOs, all designed to target the essential gene acpP upon delivery with a KFF-peptide carrier into Salmonella. Our systematic analysis of PNA, PMO, phosphorothioate (PTO)-modified DNA, 2'-methylated RNA (RNA-OMe), 2'-methoxyethylated RNA (RNA-MOE), 2'-fluorinated RNA (RNA-F), and 2'-4'-locked RNA (LNA) is based on a variety of in vitro and in vivo methods to evaluate ASO uptake, target pairing and inhibition of bacterial growth. Our data show that only PNA and PMO are efficiently delivered by the KFF peptide into Salmonella to inhibit bacterial growth. Nevertheless, the strong target binding affinity and in vitro translational repression activity of LNA and RNA-MOE make them promising modalities for antisense antibiotics that will require the identification of an effective carrier.

An engineered poly(A) tail attenuates gut ischemia/reperfusion-induced acute lung injury

BACKGROUND

Gut ischemia/reperfusion causes the release of damage-associated molecular patterns, leading to acute lung injury and high mortality. Cold-inducible ribonucleic acid-binding protein is a ribonucleic acid chaperon that binds the polyadenylation tail of messenger ribonucleic acid intracellularly. Upon cell stress, cold-inducible ribonucleic acid-binding protein is released, and extracellular cold-inducible ribonucleic acid-binding protein acts as a damage-associated molecular pattern, worsening inflammation. To inhibit extracellular cold-inducible ribonucleic acid-binding protein, we have recently developed an engineered polyadenylation tail named A12. Here, we sought to investigate the therapeutic potential of A12 in gut ischemia/reperfusion-induced acute lung injury.

METHODS

Male C57BL6/J mice underwent superior mesenteric artery occlusion and were treated with intraperitoneal A12 (0.5 nmol/g body weight) or vehicle at the time of reperfusion. Blood and lungs were collected 4 hours after gut ischemia/reperfusion. Systemic levels of extracellular cold-inducible ribonucleic acid-binding protein, interleukin-6, aspartate transaminase, alanine transaminase, and lactate dehydrogenase were determined. The pulmonary gene expression of cytokines (interleukin-6, interleukin-1β) and chemokines (macrophage-inflammatory protein-2, keratinocyte-derived chemokine) was also assessed. In addition, lung myeloperoxidase, injury score, and cell death were determined. Mice were monitored for 48 hours after gut ischemia/reperfusion for survival assessment.

RESULTS

Gut ischemia/reperfusion significantly increased the serum extracellular cold-inducible ribonucleic acid-binding protein levels. A12 treatment markedly reduced the elevated serum interleukin-6, alanine transaminase, aspartate transaminase, and lactate dehydrogenase by 53%, 23%, 23%, and 24%, respectively, in gut ischemia/reperfusion mice. A12 also significantly decreased cytokine and chemokine messenger ribonucleic acids and myeloperoxidase activity in the lungs of gut ischemia/reperfusion mice. Histological analysis revealed that A12 attenuated tissue injury and cell death in the lungs of gut ischemia/reperfusion mice. Finally, administration of A12 markedly improved the survival of gut ischemia/reperfusion mice.

CONCLUSION

A12, a novel extracellular cold-inducible ribonucleic acid-binding protein inhibitor, diminishes inflammation and mitigates acute lung injury when employed as a treatment during gut ischemia/reperfusion. Hence, the targeted approach toward extracellular cold-inducible ribonucleic acid-binding protein emerges as a promising therapeutic strategy for alleviating gut ischemia/reperfusion-induced acute lung injury.

Exploring the Therapeutic Significance of microRNAs and lncRNAs in Kidney Diseases

MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are two crucial classes of transcripts that belong to the major group of non-coding RNAs (ncRNAs). These RNA molecules have significant influence over diverse molecular processes due to their crucial role as regulators of gene expression. However, the dysregulated expression of these ncRNAs constitutes a fundamental factor in the etiology and progression of a wide variety of multifaceted human diseases, including kidney diseases. In this context, over the past years, compelling evidence has shown that miRNAs and lncRNAs could be prospective targets for the development of next-generation drugs against kidney diseases as they participate in a number of disease-associated processes, such as podocyte and nephron death, renal fibrosis, inflammation, transition from acute kidney injury to chronic kidney disease, renal vascular changes, sepsis, pyroptosis, and apoptosis. Hence, in this current review, we critically analyze the recent findings concerning the therapeutic inferences of miRNAs and lncRNAs in the pathophysiological context of kidney diseases. Additionally, with the aim of driving advances in the formulation of ncRNA-based drugs tailored for the management of kidney diseases, we discuss some of the key challenges and future prospects that should be addressed in forthcoming investigations.

Development of decoy oligonucleotide-warheaded chimeric molecules targeting STAT3

Proteolysis-targeting chimera (PROTAC) technology is a disruptive innovation in the drug development community, and over 20 PROTAC molecules are currently under clinical evaluation. These PROTAC molecules contain small-molecule warheads that bind to target proteins. Recently, oligonucleotide-warheaded PROTACs have emerged as a promising new tool to degrade DNA-binding proteins such as transcription factors. In this study, we applied an oligonucleotide-warheaded PROTAC technology to induce the degradation of signal transducer and activator of transcription 3 (STAT3), which is a hard-to-target protein. A double-stranded decoy oligonucleotide specific to STAT3 was conjugated to E3 binders (pomalidomide, VH032, and LCL161) to generate PROTAC molecules that recruited different E3 ubiquitin ligases cereblon (CRBN), von Hippel-Lindau (VHL), and inhibitor of apoptosis protein (IAP), respectively. One of the resulting PROTAC molecules, POM-STAT3, which recruits CRBN, potently induces STAT3 degradation. STAT3 degradation by POM-STAT3 was abolished by scrambling the oligonucleotide sequences of POM-STAT3 and by adding a double-stranded decoy oligonucleotide against STAT3 in a competitive manner, suggesting the significance of oligonucleotide sequences in STAT3 degradation. Moreover, POM-STAT3-induced STAT3 degradation was suppressed by the CRBN binder thalidomide, proteasome inhibitor bortezomib, E1 inhibitor MLN7243, and siRNA-mediated depletion of CRBN, indicating that STAT3 degradation is mediated by the ubiquitin-proteasome system, which involves CRBN as the responsible E3 ubiquitin ligase. Consistent with STAT3 degradation, NCI-H2087 cell viability was severely reduced following POM-STAT3 treatment. Thus, POM-STAT3 is a STAT3 degrader that potentially has cytocidal activity against cancer cells that are highly dependent on STAT3 signaling, which implies that inducing protein degradation by decoy oligonucleotide-warheaded PROTAC molecules could be harnessed to be therapeutic against oncogenic transcription factors.

Exosomal long noncoding RNA MLETA1 promotes tumor progression and metastasis by regulating the miR-186-5p/EGFR and miR-497-5p/IGF1R axes in non-small cell lung cancer

BACKGROUND

Lung cancer is the most common and deadliest cancer worldwide, and approximately 90% of all lung cancer deaths are caused by tumor metastasis. Tumor-derived exosomes could potentially promote tumor metastasis through the delivery of metastasis-related molecules. However, the function and underlying mechanism of exosomal long noncoding RNA (lncRNA) in lung cancer metastasis remain largely unclear.

METHODS

Cell exosomes were purified from conditioned media by differential ultracentrifugation and observed using transmission electron microscopy, and the size distributions were determined by nanoparticle tracking analysis. Exosomal lncRNA sequencing (lncRNA-seq) was used to identify long noncoding RNAs. Cell migration and invasion were determined by wound-healing assays, two-chamber transwell invasion assays and cell mobility tracking. Mice orthotopically and subcutaneously xenografted with human cancer cells were used to evaluate tumor metastasis in vivo. Western blot, qRT‒PCR, RNA-seq, and dual-luciferase reporter assays were performed to investigate the potential mechanism. The level of exosomal lncRNA in plasma was examined by qRT‒PCR. MS2-tagged RNA affinity purification (MS2-TRAP) assays were performed to verify lncRNA-bound miRNAs.

RESULTS

Exosomes derived from highly metastatic lung cancer cells promoted the migration and invasion of lung cancer cells with low metastatic potential. Using lncRNA-seq, we found that a novel lncRNA, lnc-MLETA1, was upregulated in highly metastatic cells and their secreted exosomes. Overexpression of lnc-MLETA1 augmented cell migration and invasion of lung cancer. Conversely, knockdown of lnc-MLETA1 attenuated the motility and metastasis of lung cancer cells. Interestingly, exosome-transmitted lnc-MLETA1 promoted cell motility and metastasis of lung cancer. Reciprocally, targeting lnc-MLETA1 with an LNA suppressed exosome-induced lung cancer cell motility. Mechanistically, lnc-MLETA1 regulated the expression of EGFR and IGF1R by sponging miR-186-5p and miR-497-5p to facilitate cell motility. The clinical datasets revealed that lnc-MLETA1 is upregulated in tumor tissues and predicts survival in lung cancer patients. Importantly, the levels of exosomal lnc-MLETA1 in plasma were positively correlated with metastasis in lung cancer patients.

CONCLUSIONS

This study identifies lnc-MLETA1 as a critical exosomal lncRNA that mediates crosstalk in lung cancer cells to promote cancer metastasis and may serve as a prognostic biomarker and potential therapeutic target for lung cancer diagnosis and treatment.

Updated Considerations for the Immunopharmacological Aspects of the "Talented mRNA Vaccines"

Messenger RNA (mRNA) vaccines belong to a new class of medications, RNA therapeutics, including both coding and non-coding RNAs. The use of mRNA as a therapy is based on the biological role of mRNA itself, namely its translation into a functional protein. The goal of mRNA vaccines is to produce a specific antigen in cells to elicit an immune response that might be prophylactic or therapeutic. The potential of mRNA as vaccine has been envisaged for years but its efficacy has been clearly demonstrated with the approval of COVID-19 vaccines in 2021. Since then, mRNA vaccines have been in the pipeline for diseases that are still untreatable. There are many advantages of mRNA vaccines over traditional vaccines, including easy and cost-effective production, high safety, and high-level antigen expression. However, the nature of mRNA itself and some technical issues pose challenges associated with the vaccines' development and use. Here we review the immunological and pharmacological features of mRNA vaccines by discussing their pharmacokinetics, mechanisms of action, and safety, with a particular attention on the advantages and challenges related to their administration. Furthermore, we present an overview of the areas of application and the clinical trials that utilize a mRNA vaccine as a treatment.

Circular RNA in cholangiocarcinoma: A systematic review and bibliometric analysis

BACKGROUND

Cholangiocarcinoma (CCA) is a common primary liver malignancy with a poor prognosis. Many studies have demonstrated the involvement of circular RNAs (circRNAs) in tumorigenesis and progression.

METHODS

Four online databases (PubMed, Web of Science, Embase, and Scopus) were searched on May 04, 2023, for original papers regarding CCA and circRNAs. Bibliometric analysis of included studies was performed on R Studio and GraphPad Prism.

RESULTS

Thirty studies were included in the systematic review and bibliometric analysis. The systematic review showed that circRNAs were involved in CCA proliferation, invasion, metastasis, chemotherapy resistance, and other biological processes and were related to the prognosis of patients and many clinicopathological features. Exosomal circRNAs provide a new idea for the early diagnosis of CCA. The bibliometric analysis showed a significant upward trend in the number of studies on CCA and circRNAs. The 30 included papers had 201 authors and were published in 22 English journals. The first paper was published in 2018, and the second paper was the most cited (148 citations).

CONCLUSION

This systematic review and bibliometric analysis demonstrates that circRNAs in CCA have not been studied enough. CircRNAs play an important role in the occurrence and progression of CCA. They may become new targets for the diagnosis, treatment, and prognostic monitoring of CCA.

An Overview of the Stability and Delivery Challenges of Commercial Nucleic Acid Therapeutics

Nucleic acid (NA)-based biopharmaceuticals have emerged as promising therapeutic modalities. NA therapeutics are a diverse class of RNA and DNA and include antisense oligonucleotides, siRNA, miRNA, mRNA, small activating RNA, and gene therapies. Meanwhile, NA therapeutics have posed significant stability and delivery challenges and are expensive. This article discusses the challenges and opportunities for achieving stable formulations of NAs with novel drug delivery systems (DDSs). Here we review the current progress in the stability issues and the significance of novel DDSs associated with NA-based biopharmaceuticals, as well as mRNA vaccines. We also highlight the European Medicines Agency (EMA) and US Food and Drug Administration (FDA)-approved NA-based therapeutics with their formulation profiles. NA therapeutics could impact future markets if the remaining challenges and requirements are addressed. Regardless of the limited information available for NA therapeutics, reviewing and collating the relevant facts and figures generates a precious resource for formulation experts familiar with the NA therapeutics' stability profile, their delivery challenges, and regulatory acceptance.

Recent progress of aptamer‒drug conjugates in cancer therapy

Aptamers are single-stranded DNA or RNA sequences that can specifically bind with the target protein or molecule via specific secondary structures. Compared to antibody-drug conjugates (ADC), aptamer‒drug conjugate (ApDC) is also an efficient, targeted drug for cancer therapy with a smaller size, higher chemical stability, lower immunogenicity, faster tissue penetration, and facile engineering. Despite all these advantages, several key factors have delayed the clinical translation of ApDC, such as in vivo off-target effects and potential safety issues. In this review, we highlight the most recent progress in the development of ApDC and discuss solutions to the problems noted above.

Hypoxia-induced lncRNA MRVI1-AS1 accelerates hepatocellular carcinoma progression by recruiting RNA-binding protein CELF2 to stabilize SKA1 mRNA

BACKGROUND

Long non-coding RNAs (lncRNAs) perform a vital role during the progression of hepatocellular carcinoma (HCC). Here, we aimed to identify a novel lncRNA involved in HCC development and elucidate the underlying molecular mechanism.

METHODS

The RT-qPCR and TCGA dataset analysis were applied to explore the expressions of MRVI1-AS1 in HCC tissues and cell lines. Statistical analysis was applied to analyze the clinical significance of MRVI1-AS1 in HCC. The functions of MRVI1-AS1 in HCC cells metastasis and growth were explored by transwell assays, wound healing assay, MTT assay, EdU assay, the intravenous transplantation tumor model, and the subcutaneous xenograft tumor model. Microarray mRNA expression analysis, dual luciferase assays, and actinomycin D treatment were used to explore the downstream target of MRVI1-AS1 in HCC cells. RIP assay was applied to assess the direct interactions between CELF2 and MRVI1-AS1 or SKA1 mRNA. Rescue experiments were employed to validate the functional effects of MRVI1-AS1, CELF2, and SKA1 on HCC cells.

RESULTS

MRVI1-AS1 was found to be dramatically upregulated in HCC and the expression was strongly linked to tumor size, venous infiltration, TNM stage, as well as HCC patients' outcome. Cytological experiments and animal experiments showed that MRVI1-AS1 promoted HCC cells metastasis and growth. Furthermore, SKA1 was identified as the downstream targeted mRNA of MRVI1-AS1 in HCC cells, and MRVI1-AS1 increased SKA1 expression by recruiting CELF2 protein to stabilize SKA1 mRNA. In addition, we found that MRVI1-AS1 expression was stimulated by hypoxia through a HIF-1-dependent manner, which meant that MRVI1-AS was a direct downstream target gene of HIF-1 in HCC.

CONCLUSION

In a word, our findings elucidated that hypoxia-induced MRVI1-AS1 promotes metastasis and growth of HCC cells via recruiting CELF2 protein to stabilize SKA1 mRNA, pointing to MRVI1-AS1 as a promising clinical application target for HCC therapy.

Identification of a novel small-molecule inhibitor of miR-29b attenuates muscle atrophy

Muscle atrophy is debilitating and can be induced by several stressors. Unfortunately, there are no effective pharmacological treatment until now. MicroRNA (miR)-29b is an important target that we identified to be commonly involved in multiple types of muscle atrophy. Although sequence-specific inhibition of miR-29b has been developed, in this study, we report a novel small-molecule miR-29b inhibitor that targets miR-29b hairpin precursor (pre-miR-29b) (Targapremir-29b-066 [TGP-29b-066]) considering both its three-dimensional structure and the thermodynamics of interaction between pre-miR-29b and the small molecule. This novel small-molecule inhibitor has been demonstrated to attenuate muscle atrophy induced by angiotensin II (Ang II), dexamethasone (Dex), and tumor necrosis factor α (TNF-α) in C2C12 myotubes, as evidenced by increase in the diameter of myotube and decrease in the expression of Atrogin-1 and MuRF-1. Moreover, it can also attenuate Ang II-induced muscle atrophy in mice, as evidenced by a similar increase in the diameter of myotube, reduced Atrogin-1 and MuRF-1 expression, AKT-FOXO3A-mTOR signaling activation, and decreased apoptosis and autophagy. In summary, we experimentally identified and demonstrated a novel small-molecule inhibitor of miR-29b that could act as a potential therapeutic agent for muscle atrophy.

An assembly-inducing PDC enabling the efficient nuclear delivery of nucleic acid for cancer stem-like cell suppression

Nucleic acid therapy is attracting great attention in diverse clinical translations because of its therapeutic advantages. As a renowned oligonucleotide therapeutical candidate in the clinical stage, AS1411 has shown outstanding tumor suppressing effects; however, its efficient delivery to the cell nucleus is critical for its anticancer effect. Herein, we identified a multifunctional peptide drug conjugate (PDC) as a safe and efficient carrier to achieve the nuclear delivery of AS1411. This PDC consists of the cell penetration peptide RW9, an HDAC inhibitor warhead (peptide C-terminus), and 5-FU (peptide N-terminus), which can coassemble with AS1411 to form nanospheres. The PDC efficiently delivered AS1411 to the nucleus of several types of cancer cells. Moreover, it reversed the stemness of a cancer stem-like cell line. Significantly, due to the assembly-induced accumulation enhancement and retention, a safe single agent concentration of PDC showed unexpected synergy with AS1411 to augment the cancer cell suppression efficiency, exemplified by the downregulation of the stemness-related proteins and the upregulation of apoptosis-related proteins. Therefore, our work presents a powerful strategy for the nuclear delivery of nucleic acid drugs by leveraging cancer-suppressing PDC as assembly inducers, which provides a powerful combination regimen in treating cancer stem-like cells.

A perspective on oligonucleotide therapy: Approaches to patient customization

It is estimated that the human genome encodes 15% of proteins that are considered to be disease-modifying. Only 2% of these proteins possess a druggable site that the approved clinical candidates target. Due to this disparity, there is an immense need to develop therapeutics that may better mitigate the disease or disorders aroused by non-druggable and druggable proteins or enzymes. The recent surge in approved oligonucleotide therapeutics (OT) indicates the imminent potential of these therapies. Oligonucleotide-based therapeutics are of intermediate size with much-improved selectivity towards the target and fewer off-target effects than small molecules. The OTs include Antisense RNAs, MicroRNA (MIR), small interfering RNA (siRNA), and aptamers, which are currently being explored for their use in neurodegenerative disorders, cancer, and even orphan diseases. The present review is a congregated effort to present the past and present of OTs and the current efforts to make OTs for plausible future therapeutics. The review provides updated literature on the challenges and bottlenecks of OT and recent advancements in OT drug delivery. Further, this review deliberates on a newly emerging approach to personalized treatment for patients with rare and fatal diseases with OT.

Targeting oncogenic KRAS with molecular brush-conjugated antisense oligonucleotides

The mutant form of the guanosine triphosphatase (GTPase) KRAS is a key driver in human tumors but remains a challenging therapeutic target, making KRAS^MUT cancers a highly unmet clinical need. Here, we report a class of bottlebrush polyethylene glycol (PEG)-conjugated antisense oligonucleotides (ASOs) for potent in vivo KRAS depletion. Owing to their highly branched architecture, these molecular nanoconstructs suppress nearly all side effects associated with DNA-protein interactions and substantially enhance the pharmacological properties of the ASO, such as plasma pharmacokinetics and tumor uptake. Systemic delivery to mice bearing human non-small-cell lung carcinoma xenografts results in a significant reduction in both KRAS levels and tumor growth, and the antitumor performance well exceeds that of current popular ASO paradigms, such as chemically modified oligonucleotides and PEGylation using linear or slightly branched PEG. Importantly, these conjugates relax the requirement on the ASO chemistry, allowing unmodified, natural phosphodiester ASOs to achieve efficacy comparable to that of chemically modified ones. Both the bottlebrush polymer and its ASO conjugates appear to be safe and well tolerated in mice. Together, these data indicate that the molecular brush-ASO conjugate is a promising therapeutic platform for the treatment of KRAS-driven human cancers and warrant further preclinical and clinical development.

Precision Anti-Cancer Medicines by Oligonucleotide Therapeutics in Clinical Research Targeting Undruggable Proteins and Non-Coding RNAs

Cancer incidence and mortality continue to increase, while the conventional chemotherapeutic drugs confer limited efficacy and relevant toxic side effects. Novel strategies are urgently needed for more effective and safe therapeutics in oncology. However, a large number of proteins are considered undruggable by conventional drugs, such as the small molecules. Moreover, the mRNA itself retains oncological functions, and its targeting offers the double advantage of blocking the tumorigenic activities of the mRNA and the translation into protein. Finally, a large family of non-coding RNAs (ncRNAs) has recently emerged that are also dysregulated in cancer, but they could not be targeted by drugs directed against the proteins. In this context, this review describes how the oligonucleotide therapeutics targeting RNA or DNA sequences, are emerging as a new class of drugs, able to tackle the limitations described above. Numerous clinical trials are evaluating oligonucleotides for tumor treatment, and in the next few years some of them are expected to reach the market. We describe the oligonucleotide therapeutics targeting undruggable proteins (focusing on the most relevant, such as those originating from the MYC and RAS gene families), and for ncRNAs, in particular on those that are under clinical trial evaluation in oncology. We highlight the challenges and solutions for the clinical success of oligonucleotide therapeutics, with particular emphasis on the peculiar challenges that render it arduous to treat tumors, such as heterogeneity and the high mutation rate. In the review are presented these and other advantages offered by the oligonucleotide as an emerging class of biotherapeutics for a new era of precision anti-cancer medicine.

TRUE Gene Silencing

TRUE gene silencing is an RNA-mediated gene expression control technology and is termed after tRNase ZL-utilizing efficacious gene silencing. In this review, I overview the potentiality of small guide RNA (sgRNA) for TRUE gene silencing as novel therapeutics. First, I describe the physiology of tRNase ZL and cellular small RNA, and then sgRNA and TRUE gene silencing. An endoribonuclease, tRNase ZL, which can efficiently remove a 3' trailer from pre-tRNA, is thought to play the role in tRNA maturation in the nucleus and mitochondria. There exist various small RNAs including miRNA and fragments from tRNA and rRNA, which can function as sgRNA, in living cells, and human cells appear to be harnessing cytosolic tRNase ZL for gene regulation together with these small RNAs. By utilizing the property of tRNase ZL to recognize and cleave micro-pre-tRNA, a pre-tRNA-like or micro-pre-tRNA-like complex, as well as pre-tRNA, tRNase ZL can be made to cleave any target RNA at any desired site under the direction of an artificial sgRNA that binds a target RNA and forms the pre-tRNA-like or micro-pre-tRNA-like complex. This general RNA cleavage method underlies TRUE gene silencing. Various examples of the application of TRUE gene silencing are reviewed including the application to several human cancer cells in order to induce apoptosis. Lastly, I discuss the potentiality of sgRNA as novel therapeutics for multiple myeloma.

Targeting SNORA38B attenuates tumorigenesis and sensitizes immune checkpoint blockade in non-small cell lung cancer by remodeling the tumor microenvironment via regulation of GAB2/AKT/mTOR signaling pathway

BACKGROUND

Non-coding RNAs (ncRNAs), including small nucleolar RNAs (snoRNAs), are widely involved in the physiological and pathological processes of human beings. While up to date, although considerable progress has been achieved in ncRNA-related pathogenesis of non-small cell lung cancer (NSCLC), the underlying mechanisms and biological significance of snoRNAs in NSCLC still need to be further clarified.

METHODS

Quantitative real-time polymerase chain reaction or RNAscope was performed to verify the expression of Small Nucleolar RNA, H/ACA Box 38B (SNORA38B) in NSCLC cell lines or clinical samples. BALB/c nude mice xenograft model or C57BL/6J mice syngeneic tumor model were estimated to detect the effects of SNORA38B in tumor growth or tumor immune microenvironment in vivo. Cytometry by time of flight, enzyme-linked immunosorbent assay and flow cytometry assay were conducted to clarify the effects and mechanisms of SNORA38B-mediated tumor immunosuppressive microenvironment. The binding activity between SNORA38B and E2F transcription factor 1(E2F1) was detected by RNA immunoprecipitation and RNA pull-down assays. Then, bioinformatics analysis and chromatin immunoprecipitation were utilized to demonstrate the regulation of GRB2-associated-binding protein 2 (GAB2) by E2F1. Moreover, the combinatorial treatment of SNORA38B locked nucleic acid (LNA) and immune checkpoint blockade (ICB) was used to treat murine Lewis lung carcinoma-derived tumor burden C57BL/6J mice to clarify the effectiveness of targeting SNORA38B in NSCLC immunotherapy.

RESULTS

SNORA38B was found highly expressed in NSCLC tissues and cell lines, and associated with worse prognosis. Further results showed that SNORA38B functioned as an oncogene via facilitating cell proliferation, migration, invasion, and inhibiting cell apoptosis in vitro and promoting tumorigenesis of NSCLC cells in vivo. SNORA38B could also recruit the CD4+FOXP3+ regulatory T cells by triggering tumor cells to secrete interleukin 10, which in turn reduced the infiltration of CD3+CD8+ T cells in NSCLC tumor microenvironment (TME), favoring tumor progression and poorer immune efficacy. Mechanistically, SNORA38B mainly distributed in the nucleus, and promoted NSCLC progression by regulating GAB2 transcription to activate protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway through directly binding with E2F1. Moreover, we found that SNORA38B LNAs were able to ameliorate CD3+CD8+ T cell infiltration in TME, which sensitized NSCLC to the treatment of ICB.

CONCLUSIONS

In conclusion, our data demonstrated that SNORA38B functioned as an oncogene in NSCLC both in vitro and in vivo at least in part by regulating the GAB2/AKT/mTOR pathway via directly binding to E2F1. SNORA38B could also sensitize NSCLC to immunotherapy, which may be a critical therapeutic target for NSCLC.

Alternative RNA Splicing Defects in Pediatric Cancers: New Insights in Tumorigenesis and Potential Therapeutic Vulnerabilities

BACKGROUND

Compared to adult cancers, pediatric cancers are uniquely characterized by a genomically stable landscape and lower tumor mutational burden. However, alternative splicing, a global cellular process that produces different mRNA/protein isoforms from a single mRNA transcript, has been increasingly implicated in the development of pediatric cancers.

DESIGN

We review the current literature on the role of alternative splicing in adult cancer, cancer predisposition syndromes, and pediatric cancers. We also describe multiple splice variants identified in adult cancers and confirmed through comprehensive genomic profiling in our institutional cohort of rare, refractory and relapsed pediatric and adolescent young adult cancer patients. Finally, we summarize the contributions of alternative splicing events to neoantigens and chemoresistance and prospects for splicing-based therapies.

RESULTS

Published dysregulated splicing events can be categorized as exon inclusion, exon exclusion, splicing factor upregulation, or splice site alterations. We observe these phenomena in cancer predisposition syndromes (Lynch syndrome, Li-Fraumeni syndrome, CHEK2) and pediatric leukemia (B-ALL), sarcomas (Ewing sarcoma, rhabdomyosarcoma, osteosarcoma), retinoblastoma, Wilms tumor, and neuroblastoma. Within our institutional cohort, we demonstrate splice variants in key regulatory genes (CHEK2, TP53, PIK3R1, MDM2, KDM6A, NF1) that resulted in exon exclusion or splice site alterations, which were predicted to impact functional protein expression and promote tumorigenesis. Differentially spliced isoforms and splicing proteins also impact neoantigen creation and treatment resistance, such as imatinib or glucocorticoid regimens. Additionally, splice-altering strategies with the potential to change the therapeutic landscape of pediatric cancers include antisense oligonucleotides, adeno-associated virus gene transfers, and small molecule inhibitors.

CONCLUSIONS

Alternative splicing plays a critical role in the formation and growth of pediatric cancers, and our institutional cohort confirms and highlights the broad spectrum of affected genes in a variety of cancers. Further studies that elucidate the mechanisms of disease-inducing splicing events will contribute toward the development of novel therapeutics.

Antisense oligonucleotide gapmers containing phosphoryl guanidine groups reverse MDR1-mediated multiple drug resistance of tumor cells

Antisense gapmer oligonucleotides containing phosphoryl guanidine (PG) groups, e.g., 1,3-dimethylimidazolidin-2-imine, at three to five internucleotidic positions adjacent to the 3' and 5' ends were prepared via the Staudinger chemistry, which is compatible with conditions of standard automated solid-phase phosphoramidite synthesis for phosphodiester and, notably, phosphorothioate linkages, and allows one to design a variety of gapmeric structures with alternating linkages, and deoxyribose or 2'-O-methylribose backbone. PG modifications increased nuclease resistance in serum-containing medium for more than 21 days. Replacing two internucleotidic phosphates by PG groups in phosphorothioate-modified oligonucleotides did not decrease their cellular uptake in the absence of lipid carriers. Increasing the number of PG groups from two to seven per oligonucleotide reduced their ability to enter the cells in the carrier-free mode. Cationic liposomes provided similar delivery efficiency of both partially PG-modified and unmodified oligonucleotides. PG-gapmers were designed containing three to four PG groups at both wings and a central "window" of seven deoxynucleotides with either phosphodiester or phosphorothioate linkages targeted to MDR1 mRNA providing multiple drug resistance of tumor cells. Gapmers efficiently silenced MDR1 mRNA and restored the sensitivity of tumor cells to chemotherapeutics. Thus, PG-gapmers can be considered as novel, promising types of antisense oligonucleotides for targeting biologically relevant RNAs.

A naked antisense oligonucleotide with phosphorothioate linkages is taken up intracellularly more efficiently but functions less effectively

We have been developing a gene silencing technology by harnessing a tRNA 3' processing endoribonuclease, tRNase Z^L, with antisense oligonucleotides. Here, to further improve this technology, we investigated how the length and the modifications of naked oligonucleotides affect the efficiency of their uptake by HeLa, HEK293, and HL60 cells by flow cytometry and fluorescence microscopy. 7-30-nt Alexa-Fluor-568-labeled DNAs with phosphorothioate linkages and 7-30-nt Alexa-Fluor-568-labeled, 2'-O-methylated RNAs without phosphorothioate linkages were examined, and, on the whole, longer oligonucleotides were shown to be intracellularly taken up more efficiently. In addition, a 2'-O-methoxyethylated RNA without phosphorothioate linkages, a 2'-fluoriated RNA without phosphorothioate linkages, a 2'-O-methylated RNA with phosphorothioate linkages, and a 2'-O-methylated RNA with phosphorothioate linkages and LNA modifications of 5'-/3'-terminal nucleotides were examined. The oligonucleotides with phosphorothioate linkages were taken up by the cells more efficiently than those without the linkages. Furthermore, we examined how the phosphorothioate linkages of oligonucleotides affect their antisense effects using 22-nt anti-miR16 oligonucleotides with and without phosphorothioate linkages. The latter oligonucleotide decreased the miR16 level much more intensively than the former, although the latter was intracellularly taken up much less efficiently. These observations may be not generalized and differ depending on features of oligonucleotides and cell types. Taken together these results suggest that the productive uptake efficiency for an antisense oligonucleotide needs to be considered to select its length and modifications.

Circular RNAs: characteristics, biogenesis, mechanisms and functions in liver cancer

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most common malignancies globally. Despite aggressive and multimodal treatment regimens, the overall survival of HCC patients remains poor. MAIN: Circular RNAs (circRNAs) are noncoding RNAs (ncRNAs) with covalently closed structures and tissue- or organ-specific expression patterns in eukaryotes. They are highly stable and have important biological functions, including acting as microRNA sponges, protein scaffolds, transcription regulators, translation templates and interacting with RNA-binding protein. Recent advances have indicated that circRNAs present abnormal expression in HCC tissues and that their dysregulation contributes to HCC initiation and progression. Furthermore, researchers have revealed that some circRNAs might serve as diagnostic biomarkers or drug targets in clinical settings. In this review, we systematically evaluate the characteristics, biogenesis, mechanisms and functions of circRNAs in HCC and further discuss the current shortcomings and potential directions of prospective studies on liver cancer-related circRNAs.

CONCLUSION

CircRNAs are a novel class of ncRNAs that play a significant role in HCC initiation and progression, but their internal mechanisms and clinical applications need further investigation.

The Long Non-Coding RNA H19 Drives the Proliferation of Diffuse Intrinsic Pontine Glioma with H3K27 Mutation

Diffuse intrinsic pontine glioma (DIPG) is an incurable paediatric malignancy. Identifying the molecular drivers of DIPG progression is of the utmost importance. Long non-coding RNAs (lncRNAs) represent a large family of disease- and tissue-specific transcripts, whose functions have not yet been elucidated in DIPG. Herein, we studied the oncogenic role of the development-associated H19 lncRNA in DIPG. Bioinformatic analyses of clinical datasets were used to measure the expression of H19 lncRNA in paediatric high-grade gliomas (pedHGGs). The expression and sub-cellular location of H19 lncRNA were validated in DIPG cell lines. Locked nucleic acid antisense oligonucleotides were designed to test the function of H19 in DIPG cells. We found that H19 expression was higher in DIPG vs. normal brain tissue and other pedHGGs. H19 knockdown resulted in decreased cell proliferation and survival in DIPG cells. Mechanistically, H19 buffers let-7 microRNAs, resulting in the up-regulation of oncogenic let-7 target (e.g., SULF2 and OSMR). H19 is the first functionally characterized lncRNA in DIPG and a promising therapeutic candidate for treating this incurable cancer.

Modified Nucleosides, Nucleotides and Nucleic Acids via Click Azide-Alkyne Cycloaddition for Pharmacological Applications

The click azide = alkyne 1,3-dipolar cycloaddition (click chemistry) has become the approach of choice for bioconjugations in medicinal chemistry, providing facile reaction conditions amenable to both small and biological molecules. Many nucleoside analogs are known for their marked impact in cancer therapy and for the treatment of virus diseases and new targeted oligonucleotides have been developed for different purposes. The click chemistry allowing the tolerated union between units with a wide diversity of functional groups represents a robust means of designing new hybrid compounds with an extraordinary diversity of applications. This review provides an overview of the most recent works related to the use of click chemistry methodology in the field of nucleosides, nucleotides and nucleic acids for pharmacological applications.