Inhibition of survivin by 2'-O-methyl phosphorothioate-modified steric-blocking antisense oligonucleotides

Chemically modified antisense oligonucleotide (ASO) has been established as a successful therapeutic strategy for treating various human diseases. To date, ten ASO drugs, which are capable of either inducing mRNA degradation via RNase H recruitment (fomivirsen, mipomersen, inotersen, volanesorsen and tofersen) or splice modulation (eteplirsen, nusinersen, golodirsen, viltolarsen and casimersen), have been approved by the regulatory agencies for market entry. Nonetheless, none of these approved drugs are prescribed as cancer therapy. Towards this, we have developed steric-blocking ASOs targeting BIRC5 - a well-validated oncogene. Initial screening was performed by transfection of HepG2 cells with seven BIRC5 exon-2 targeting, uniformly 2'-OMe-PS modified ASOs at 400 nM respectively, leading to the identification of two best-performing candidates ASO-2 and ASO-7 in reducing the production of BIRC5 mRNA. Subsequent dose-response assay was conducted via transfection of HepG2 cells by different concentrations (400, 200, 100, 50, 25 nM) of ASO-2 and ASO-7 respectively, showing that both ASOs consistently and efficiently inhibited BIRC5 mRNA expression in a dose-dependent manner. Furthermore, western blot analysis confirmed that ASO-7 could significantly repress survivin production on protein level. Based on our preliminary results, we believe that ASO-7 could be a useful BIRC5 inhibitor for both research purpose and therapeutic development.

Splice-Modulating Antisense Oligonucleotides as Therapeutics for Inherited Metabolic Diseases

The last decade (2013-2023) has seen unprecedented successes in the clinical translation of therapeutic antisense oligonucleotides (ASOs). Eight such molecules have been granted marketing approval by the United States Food and Drug Administration (US FDA) during the decade, after the first ASO drug, fomivirsen, was approved much earlier, in 1998. Splice-modulating ASOs have also been developed for the therapy of inborn errors of metabolism (IEMs), due to their ability to redirect aberrant splicing caused by mutations, thus recovering the expression of normal transcripts, and correcting the deficiency of functional proteins. The feasibility of treating IEM patients with splice-switching ASOs has been supported by FDA permission (2018) of the first "N-of-1" study of milasen, an investigational ASO drug for Batten disease. Although for IEM, owing to the rarity of individual disease and/or pathogenic mutation, only a low number of patients may be treated by ASOs that specifically suppress the aberrant splicing pattern of mutant precursor mRNA (pre-mRNA), splice-switching ASOs represent superior individualized molecular therapeutics for IEM. In this work, we first summarize the ASO technology with respect to its mechanisms of action, chemical modifications of nucleotides, and rational design of modified oligonucleotides; following that, we precisely provide a review of the current understanding of developing splice-modulating ASO-based therapeutics for IEM. In the concluding section, we suggest potential ways to improve and/or optimize the development of ASOs targeting IEM.

Metallic nanostructure-based aptasensors for robust detection of proteins

There is a significant need for fast, cost-effective, and highly sensitive protein target detection, particularly in the fields of food, environmental monitoring, and healthcare. The integration of high-affinity aptamers with metal-based nanomaterials has played a crucial role in advancing the development of innovative aptasensors tailored for the precise detection of specific proteins. Aptamers offer several advantages over commonly used molecular recognition methods, such as antibodies. Recently, a variety of metal-based aptasensors have been established. These metallic nanomaterials encompass noble metal nanoparticles, metal oxides, metal-carbon nanotubes, carbon quantum dots, graphene-conjugated metallic nanostructures, as well as their nanocomposites, metal-organic frameworks (MOFs), and MXenes. In general, these materials provide enhanced sensitivity through signal amplification and transduction mechanisms. This review primarily focuses on the advancement of aptasensors based on metallic materials for the highly sensitive detection of protein targets, including enzymes and growth factors. Additionally, it sheds light on the challenges encountered in this field and outlines future prospects. We firmly believe that this review will offer a comprehensive overview and fresh insights into metallic nanomaterials-based aptasensors and their capabilities, paving the way for the development of innovative point-of-care (POC) diagnostic devices.

Splice-Switching Antisense Oligonucleotides Targeting Extra- and Intracellular Domains of Epidermal Growth Factor Receptor in Cancer Cells

Cancer is one of the leading causes of death globally. Epidermal growth factor receptor is one of the proteins involved in cancer cell proliferation, differentiation, and invasion. Antisense oligonucleotides are chemical nucleic acids that bind to target messenger ribonucleic acid and modulate its expression. Herein, we demonstrate the efficacy of splice-modulating antisense oligonucleotides to target specific exons in the extracellular (exon 3) and intracellular (exon 18, 21) domains of epidermal growth factor receptor. These antisense oligonucleotides were synthesized as 25mer 2'-O methyl phosphorothioate-modified ribonucleic acids that bind to complementary specific regions in respective exons. We found that PNAT524, PNAT525, PNAT576, and PNAT578 effectively skipped exon 3, exon 18, and exon 21 in glioblastoma, liver cancer, and breast cancer cell lines. PNAT578 treatment also skipped partial exon 19, complete exon 20, and partial exon 21 in addition to complete exon 21 skipping. We also found that a cocktail of PNAT576 and PNAT578 antisense oligonucleotides performed better than their individual counterparts. The migration potential of glioblastoma cancer cells was reduced to a greater extent after treatment with these antisense oligonucleotides. We firmly believe that using these splice-modulating antisense oligonucleotides in combination with existing EGFR-targeted therapies could improve therapeutic outcomes.

Nanoparticles-assisted aptamer biosensing for the detection of environmental pathogens

Given the importance of public health, it is crucial to develop quick, targeted, highly sensitive, and accurate technologies to monitor pathogenic microbes in response to the growing concerns of food and environmental safety. Although conventional approaches for microbiological detection are available, they are laborious, and often skill demanding. Therefore, such approaches are incompetent in the on-site or high-throughput assessment of pathogenic microbes. Numerous efforts have been made to develop biosensors that use nucleic acid aptamer as the biorecognition element, which would avoid the abovementioned limitations. Incorporating nanomaterials (NMs) into aptamer-based biosensors (aptasensors) improves their sensitivity and specificity, opening exciting possibilities for various applications, such as bioanalysis of food and environmental samples. Over the last decade, nanomaterial-conjugated aptasensors have seen a steadily rising demand. To this end, the main goal of this study is to demonstrate the novelty in the design of nanomaterial-conjugated aptasensors and how they can be used to detect different pathogenic microbes in water and food. The intent of this paper is to evaluate the cutting-edge techniques that have appeared in nano-aptasensors throughout the past few years, such as manufacturing procedures, analytical credibility, and sensing mechanisms. Additionally, the fundamental performance parameters of aptasensing techniques (such as detection limits, and sensing ranges response) were also used to evaluate their practical applicability. Finally, it is anticipated that this study will inspire innovative ideas and techniques for the construction and use of aptasensors for monitoring pathogenic microorganisms in food, drinks, recreational water, and wastewater.

Development of a Novel DNA Oligonucleotide Targeting Low-Density Lipoprotein Receptor

Low-density lipoprotein receptor (LDL-R) is a cell surface receptor protein expressed in a variety of solid cancers, including lung, colon, breast, brain, and liver, and therefore it opens up opportunities to deliver lysosome-sensitive anti-cancer agents, especially synthetic nucleic acid-based therapeutic molecules. In this study, we focused on developing novel nucleic acid molecules specific to LDL-R. For this purpose, we performed in vitro selection procedure via systematic evolution of ligands by exponential enrichment (SELEX) methodologies using mammalian cell-expressed human recombinant LDL-R protein as a target. After 10 rounds of selections, we identified a novel DNA oligonucleotide aptamer, RNV-L7, that can bind specifically to LDL-R protein with high affinity and specificity (KD = 19.6 nM). Furthermore, flow cytometry and fluorescence imaging assays demonstrated efficient binding to LDL-R overexpressed human cancer cells, including Huh-7 liver cancer cells and MDA-MB-231 breast cancer cells, with a binding affinity of ∼200 nM. Furthermore, we evaluated the functional potential of the developed LDL-R aptamer RNV-L7 by conjugating with a previously reported miR-21 targeting DNAzyme for inhibiting miR-21 expression. The results showed that the miR-21 DNAzyme-RNV-L7 aptamer chimera efficiently reduced the expression of miR-21 in Huh-7 liver cancer cells. As currently there are no reports on LDL-R aptamer development, we think that RNV-L7 could be beneficial toward the development of targeted cancer therapeutics.

Synthesis of a Morpholino Nucleic Acid (MNA)-Uridine Phosphoramidite, and Exon Skipping Using MNA/2'-O-Methyl Mixmer Antisense Oligonucleotide

In this study, we synthesised a morpholino nucleoside-uridine (MNA-U) phosphoramidite and evaluated the potential of a MNA-modified antisense oligonucleotide (AO) sequences to induce exon 23 skipping in mdx mouse myotubes in vitro towards extending the applicability of morpholino chemistry with other nucleotide monomers. We designed, synthesised, and compared exon skipping efficiencies of 20 mer MNA-modified 2'-O-methyl RNA mixmer AO on a phosphorothioate backbone (MNA/2'-OMePS) to the corresponding fully modified 2'-O-methyl RNA AO (2'-OMePS) as a control. Our results showed that the MNA/2'-OMePS efficiently induced exon 23 skipping. As expected, the 2'-OMePS AO control yielded efficient exon 23 skipping. Under the applied conditions, both the AOs showed minor products corresponding to exon 22/23 dual exon skipping in low yield. As these are very preliminary data, more detailed studies are necessary; however, based on the preliminary results, MNA nucleotides might be useful in constructing antisense oligonucleotides.