miRNA Activity Research Articles

Unraveling the Regulatory Role of HuR/microRNA Axis in Colorectal Cancer Tumorigenesis.

Colorectal cancer (CRC) remains a significant global health burden with high incidence and mortality. MicroRNAs (miRNAs) are small non-protein coding transcripts, conserved throughout evolution, with an important role in CRC tumorigenesis, and are either upregulated or downregulated in various cancers. RNA-binding proteins (RBPs) are known as essential regulators of miRNA activity. Human antigen R (HuR) is a prominent RBP known to drive tumorigenesis with a pivotal role in CRC. In this review, we discuss the regulatory role of the HuR/miRNA axis in CRC. Interestingly, miRNAs can directly target HuR, altering its expression and activity. However, HuR can also stabilize or degrade miRNAs, forming complex feedback loops that either activate or block CRC-associated signaling pathways. Dysregulation of the HuR/miRNA axis contributes to CRC initiation and progression. Additionally, HuR-miRNA regulation by other small non-coding RNAs, circular RNA (circRNAs), or long-non-coding RNAs (lncRNAs) is also explored here. Understanding this HuR-miRNA interplay could reveal novel biomarkers with better diagnostic or prognostic accuracy.

Predictive action of oncomiR in suppressing TP53 signaling pathway in hypoxia-conditioned colon cancer cell line HCT-116.

Hypoxia-induced heterogeneity in colorectal cancer (CRC) significantly impacts patient survival by promoting chemoresistance. These conditions alter the regulation of miRNAs, key regulators of crucial processes like proliferation, apoptosis, and invasion, leading to tumor progression. Despite their promising potential as diagnostic and therapeutic targets, the underlying mechanisms by which miRNAs influence hypoxia-mediated tumorigenesis remain largely unexplored. This study aims to elucidate the action of miRNAs in HCT-116 colorectal cancer stem cells (CSCs) under hypoxia, providing valuable insights into their role in tumor adaptation and progression. MiRNA expression was determined using Nanostring nCounter, and bioinformatic analysis was performed to explain the molecular pathway. A total of 50 miRNAs were obtained with an average count of ≥ 20 reads for comparative expression analysis. The results showed that hypoxia-affected 36 oncomiRs were increased in HCT-116, and 14 suppressor-miRs were increased in MSCs. The increase in miRNA expression occurred consistently from normoxia to hypoxia and significantly differed between mesenchymal stem cells (MSCs) and HCT-116. Furthermore, miR-16-5p and miR-29a-3p were dominant in regulating the p53 signaling pathway, which is thought to be related to the escape mechanism against hypoxia and maintaining cell proliferation. More research with a genome-transcriptome axis approach is needed to fully understand miRNAs' role in adapting CRC cells and MSCs to hypoxia. Further research could focus on developing specific biomarkers for diagnosis. In addition, anti-miR can be developed as a therapy to prevent cancer proliferation or inhibit the adaptation of cancer cells to hypoxia.

MBNL splicing factors regulate the microtranscriptome of skeletal muscles.

Muscleblind like splicing regulators (MBNLs) govern various RNA-processing steps, including alternative splicing, polyadenylation, RNA stabilityand mRNA intracellular localization. In myotonic dystrophy type 1 (DM1), the most common muscular dystrophy in adults, MBNLs are sequestered on toxic RNA containing expanded CUG repeats, which leads to disruption of MBNL-regulated processes and disease features of DM1. Herein, we show the significance of MBNLs in regulating microtranscriptome dynamics during the postnatal development of skeletal muscles and in microRNA (miRNA) misregulation observed in mouse models and patients with DM1. We identify multiple miRNAs sensitive to MBNL proteins insufficiency and reveal that many of them were postnatally regulated, which correlates with increases in the activity of these proteins during this process. In adult Mbnl1-knockout mice, miRNA expression exhibited an adult-to-newborn shift. We hypothesize that Mbnl1 deficiency influences miRNA levels through a combination of mechanisms. First, the absence of Mbnl1 protein results in alterations to the levels of pri-miRNAs. Second, MBNLs affect miRNA biogenesis by regulating the alternative splicing of miRNA primary transcripts. We propose that the expression of miR-23b, miR-27b and miR-24-1, produced from the same cluster, depends on the MBNL-sensitive inclusion of alternative exons containing miRNA sequences. Our findings suggest that MBNL sequestration in DM1 is partially responsible for altered miRNA activity. This study provides new insights into the biological roles and functions of MBNL proteins as regulators of miRNA expression in skeletal muscles.

Increasing MicroRNA Abundance by Targeting Biogenesis from the Primary Transcript with Steric-Blocking Antisense Oligonucleotides.

MicroRNAs (miRNAs) are regulators of gene expression, and their dysregulation is linked to cancer and other diseases, making them important therapeutic targets. Several strategies for targeting and modulating miRNA activity are being explored. For example, steric blocking antisense oligonucleotides (ASOs) can reduce miRNA activity by either blocking binding sites on specific mRNAs or base-pairing to the miRNA itself to prevent its interaction with the target mRNAs. ASOs have been less explored as a tool to elevate miRNA levels, which could also be beneficial for treating disease. In this study, using the PKD1/miR-1225 gene locus as an example, where miR-1225 is located within a PKD1 intron, we demonstrate an ASO-based strategy that increases miRNA abundance by enhancing biogenesis from the primary miRNA transcript. Disruptions in PKD1 and miR-1225 are associated with autosomal dominant polycystic kidney disease (ADPKD) and various cancers, respectively, making them important therapeutic targets. We investigated PKD1 sequence variants reported in ADPKD that are located within the sequence shared by miR-1225 and PKD1, and identified one that causes a reduction in miR-1225 without affecting PKD1. We show that this reduction in miR-1225 can be recovered by treatment with a steric-blocking ASO. The ASO-induced increase in miR-1225 correlates with a decrease in the abundance of predicted miR-1225 cellular mRNA targets. This study demonstrates that miRNA abundance can be elevated using ASOs targeted to the primary transcript. This steric-blocking ASO-based approach has broad potential application as a therapeutic strategy for diseases that could be treated by modulating miRNA biogenesis.

Optimization of fine-needle aspiration biopsy of the thyroid nodes in complex diagnostic situations

Purpose of the study. To identify the most informative combinations of small non-coding RNA molecules (miRNA) associated with malignant tumors of the thyroid gland (TG) in patients with nodular formations with an uncertain conclusion based on fine needle aspiration biopsy (FNA) and the absence of gene mutations.Materials and methods. The study included 83 patients with thyroid nodules according to the results of ultrasound examination with an indefinite cytological conclusion based on FAB materials (category III–V according to the Bethesda classification) and the absence of V600E mutations in the BRAF gene, NRAS, HRAS, KRAS genes in the molecular genetic study of the aspirate. Expression activity of miRNA was determined by realtime PCR in aspirate. Using cluster analysis, homogeneous groups of miRNAs associated with malignant thyroid lesions in patients were identified.Results. In the cells of thyroid nodules obtained during FNA, malignant lesions are associated with an increase in the expression activity of miRNA‑146b,–221,–222,–885–5p and a decrease in the expression of miRNA‑455–3p and miRNA‑574–3p. Reciprocal changes in expression activity in pairs miRNA‑146b/miRNA‑574–3p, miRNA‑221/miRNA‑455–3p, miRNA‑222/miRNA‑574–3p, miRNA‑885–5p/miRNA‑574–3p are more informative when differential diagnosis of benign and malignant thyroid formations than assessing the expression of individual miRNAs.Conclusion. With an uncertain cytological conclusion based on the FAB data of thyroid nodules (categories III–V according to the Bethesda classification) and negative results of a molecular genetic study regarding gene mutations, it is recommended to direct further diagnostic search in determining the expression in the aspirate of miRNA‑146b,–221,–222,–885–5p,–455–3p,–574–3p.

Consumption of Fructooligosaccharides Influences the Action of Fecal MicroRNAs in Altering the Structure of Cultured Gut Microbiota in Mice.

Fecal microRNAs (miRNAs) derived from intestinal epithelial cells have been suggested to influence gut microbiota homeostasis. We recently showed that supplementing murine fecal small RNAs, most likely miRNAs, alters the structure of cultured fecal microbiota in a sequence-dependent manner. The present study investigated the effect of consuming fructooligosaccharides (FOS) on the action of fecal small RNAs in altering the structure of cultured fecal microbiota. Female C57BL/6J mice were allowed free access to AIN-93G diet, and tap water supplemented with or without 4% (w/v) FOS for 2 wk. As assessed by 16S rRNA gene sequence analysis in cecal contents, the gut microbiota structure differed between mice supplemented with and without FOS. Fecal bacteria isolated from the cecal contents of mice without FOS supplementation were cultured for 24 h under anaerobic conditions. The structure of cultured microbiota differed between the cultures supplemented with small RNAs isolated from the cecal contents of mice supplemented with and without FOS. Microarray analysis showed that the miRNA profile in the cecal contents differed between mice supplemented with and without FOS. We propose that FOS consumption influences the action of intestinal epithelial cell-derived miRNAs in altering the structure of cultured gut microbiota, and such FOS action is associated with changes in the profile of miRNAs. It may be possible that intestinal epithelial cell-derived miRNAs contribute, at least in part, to diet-induced alteration of gut microbiota.

A New Frontier in Phytotherapy: Harnessing the Therapeutic Power of Medicinal Herb-derived miRNAs.

Medicinal herbs have been utilized in the treatment of various pathologic conditions, including neoplasms, organ fibrosis, and diabetes mellitus. However, the precise pharmacological actions of plant miRNAs in animals remain to be fully elucidated, particularly in terms of their therapeutic efficacy and mechanism of action. In this review, some important miRNAs from foods and medicinal herbs are presented. Plant miRNAs exhibit a range of pharmacological properties, such as anti-cancer, anti-fibrosis, anti-viral, anti-inflammatory effects, and neuromodulation, among others. These results have not only demonstrated a cross-species regulatory effect, but also suggested that the miRNAs from medicinal herbs are their bioactive components. This shows a promising prospect for plant miRNAs to be used as drugs. Here, the pharmacological properties of plant miRNAs and their underlying mechanisms have been highlighted, which can provide new insights for clarifying the therapeutic mechanisms of medicinal herbs and suggest a new way for developing therapeutic drugs.

Radio-miRs: a comprehensive view of radioresistance-related microRNAs.

Radiotherapy is a key treatment option for a wide variety of human tumors, employed either alone or alongside with other therapeutic interventions. Radiotherapy uses high-energy particles to destroy tumor cells, blocking their ability to divide and proliferate. The effectiveness of radiotherapy is due to genetic and epigenetic factors that determine how tumor cells respond to ionizing radiation. These factors contribute to the establishment of resistance to radiotherapy, which increases the risk of poor clinical prognosis of patients. Although the mechanisms by which tumor cells induce radioresistance are unclear, evidence points out several contributing factors including the overexpression of DNA repair systems, increased levels of reactive oxygen species, alterations in the tumor microenvironment, and enrichment of cancer stem cell populations. In this context, dysregulation of microRNAs or miRNAs, critical regulators of gene expression, may influence how tumors respond to radiation. There is increasing evidence that miRNAs may act as sensitizers or enhancers of radioresistance, regulating key processes such as the DNA damage response and the cell death signaling pathway. Furthermore, expression and activity of miRNAs have shown informative value in overcoming radiotherapy and long-term radiotoxicity, revealing their potential as biomarkers. In this review, we will discuss the molecular mechanisms associated with the response to radiotherapy and highlight the central role of miRNAs in regulating the molecular mechanisms responsible for cellular radioresistance. We will also review radio-miRs, radiotherapy-related miRNAs, either as sensitizers or enhancers of radioresistance that hold promise as biomarkers or pharmacological targets to sensitize radioresistant cells.

Research progress on anti-cancer mechanism of salidroside regulating miRNA-mRNA signaling axis

Abstract MiRNA (MicroRNA) can target and regulate mRNA, thereby influencing the biological processes of tumors. The extract of Tibetan medicine Rhodiola demonstrates anti-tumor effects by targeting and regulating cancer-related signaling molecules and pathways. This review aims to pave the way for integrating salidroside into clinical practice, fully leverage its multi-effective and multi-targeted biological effects, and innovate approaches to tumor prevention and management, thus enhancing cancer prognosis. We initially delve into the occurrence and mechanism of action of miRNA, as well as the anti-tumor mechanism of the miRNA-mRNA signaling axis. Additionally, it was described that salidroside can hinder cancer cell proliferation by inducing autophagy and apoptosis, inhibiting cell metastasis and invasion, and modulating the tumor microenvironment and cell cycle. Moreover, examples from lung cancer, gastric cancer, and nasopharyngeal carcinoma confirm that salidroside regulates the onset and progression of tumors through the miRNA-mRNA signaling axis. This groundbreaking discovery carries significant implications for cancer diagnosis and treatment, offering a novel pathway for therapeutic intervention.

Widespread changes to the translational landscape in a maize microRNA biogenesis mutant.

MicroRNAs are short, non-coding RNAs that repress gene expression in both plants and animals and have diverse functions related to growth, development, and stress responses. The ribonuclease, DICER-LIKE1 (DCL1) is required for two steps in plant miRNA biogenesis: cleavage of the primary miRNAs (pri-miRNAs) to release a hairpin structure, called the precursor miRNA (pre-miRNA) and cleavage of the pre-miRNA to generate the miRNA/miRNA* duplex. The mature miRNA guides the RNA-induced silencing complex to target RNAs with complementary sequences, resulting in translational repression and/or RNA cleavage of target mRNAs. However, the relative contribution of translational repression versus mRNA degradation by miRNAs remains unknown at the genome-level in crops, especially in maize. The maize fuzzy tassel (fzt) mutant contains a hypomorphic mutation in DCL1 resulting in broad developmental defects. While most miRNAs are reduced in fzt, the levels of miRNA-targeted mRNAs are not dramatically increased, suggesting that translational regulation by miRNAs may be common. To gain insight into the repression mechanism of plant miRNAs, we combined ribosome profiling and RNA-sequencing to globally survey miRNA activities in maize. Our data indicate that translational repression contributes significantly to regulation of most miRNA targets and that approximately one-third of miRNA targets are regulated primarily at the translational level. Surprisingly, ribosomes appear altered in fzt mutants suggesting that DCL1 may also have a role in ribosome biogenesis. Thus, DICER-LIKE1 shapes the translational landscape in plants through both miRNA-dependent and miRNA-independent mechanisms.

Exploring the anti-EBV potential of suberoylanilide hydroxamic acid: Induction of apoptosis in infected cells through suppressing BART gene expression and inducing lytic infection

Epstein-Barr virus (EBV) is linked to lymphoma and epithelioma but lacks drugs specifically targeting EBV-positive tumors. BamHI A Rightward Transcript (BART) miRNAs are expressed in all EBV-positive tumors, suppressing both lytic infection and host cell apoptosis. We identified suberoylanilide hydroxamic acid (SAHA), an inhibitor of histone deacetylase enzymes, as an agent that suppresses BART promoter activity and transcription of BART miRNAs. SAHA treatment demonstrated a more pronounced inhibition of cell proliferation in EBV-positive cells compared to EBV-negative cells, affecting both p53 wild-type and mutant gastric epithelial cells. SAHA treatment enhanced lytic infection in wild-type EBV-infected cells, while also enhancing cell death in BZLF1-deficient EBV-infected cells. It reduced BART gene expression by 85% and increased the expression of proapoptotic factors targeted by BART miRNAs. These findings suggest that SAHA not only induces lytic infection but also leads to cell death by suppressing BART miRNA transcription and promoting the apoptotic program.

Exosomal miR-196a-5p contributes to esophageal squamous cell carcinoma malignant progression by inhibiting ITM2B.

Exosomes from cancer cells function as carriers to spread or transport specific microRNAs (miRNAs) to distant sites to exert their effects, but the mechanism of exosomal miRNA action in esophageal squamous cell carcinoma (ESCC) has not been fully explained. Therefore, in this study, we were interested in the impact of exosomal miR-196a-5p in ESCC progression. We found that miR-196a-5p was expressed enriched in clinical tissues, ESCC cells, and exosomes. Functionally, depletion of miR-196a-5p impeded ESCC cell growth, migration, and invasion, whereas overexpression of miR-196a-5p produced the opposite results. Moreover, enhancement of exosomal miR-196a-5p in recipient ESCC cells triggered more intense proliferation and migration. Mechanistically, we identified integral membrane protein 2B (ITM2B) as a direct target of miR-196a-5p. Silencing of ITM2B partially counteracted the inhibitory effect of miR-196a-5p inhibitors on the malignant phenotype of ESCC. Furthermore, in vivo, lower miR-196a-5p levels triggered by the introduction of antagomiR-196a-5p resulted in the generation of smaller volume and weight xenograft tumors. Thus, our results demonstrated novel mechanisms of exosomal and intracellular miR-196a-5p-mediated ESCC growth and migration and identify the interaction of miR-196a-5p with ITM2B. These works might provide new targets and basis for the development of clinical treatment options for ESCC.

Upregulation of YPEL3 expression and induction of human breast cancer cell death by microRNAs

MicroRNAs (miRNAs), molecules comprising 18–22 nucleotides, regulate expression of genes post-transcriptionally at the 3′ untranslated region of target mRNAs. However, the biological roles and mechanisms of action of miRNAs in breast cancer remain unelucidated. Thus, in this study, we aimed to investigate the functions and possible mechanisms of action of miRNAs in breast cancer to suppress carcinogenesis. Using miRNA databases, we selected miR-34a and miR-605-5p to downregulate MDM4 and MDM2, respectively, because these ubiquitin E3 ligases degrade p53 and promote carcinogenesis. Results showed that miR-34a and miR-605-5p suppressed MDM4 and MDM2 expression, respectively. Moreover, they reduced the expression of yes‑associated protein 1 (YAP1), a well-known oncogene involved in Hippo signaling, but upregulated the mRNA and protein expression of yippee-like 3 (YPEL3). To elucidate whether these miRNAs promote cellular senescence and death through YPEL3 upregulation, we examined their effects on cellular proliferation, SA-β-gal activity, and mitochondrial activity in human breast cancer MCF-7 cells. Given their upregulating effect on YPEL3 expression, miR-34a and miR-605-5p increased the number of β-galactosidase-positive cells and depolarized live cells (by 10%–12%). These data suggest that miR-34a and miR-605-5p promote cellular senescence and cell death. Thus, they may act as tumor suppressors by inducing Hippo signaling and may serve as novel therapeutic agents in breast cancer treatment.

The TGFβ Induced MicroRNAome of the Trabecular Meshwork.

Primary open-angle glaucoma (POAG) is a progressive optic neuropathy with a complex, multifactorial aetiology. Raised intraocular pressure (IOP) is the most important clinically modifiable risk factor for POAG. All current pharmacological agents target aqueous humour dynamics to lower IOP. Newer therapeutic agents are required as some patients with POAG show a limited therapeutic response or develop ocular and systemic side effects to topical medication. Elevated IOP in POAG results from cellular and molecular changes in the trabecular meshwork driven by increased levels of transforming growth factor β (TGFβ) in the anterior segment of the eye. Understanding how TGFβ affects both the structural and functional changes in the outflow pathway and IOP is required to develop new glaucoma therapies that target the molecular pathology in the trabecular meshwork. In this study, we evaluated the effects of TGF-β1 and -β2 treatment on miRNA expression in cultured human primary trabecular meshwork cells. Our findings are presented in terms of specific miRNAs (miRNA-centric), but given miRNAs work in networks to control cellular pathways and processes, a pathway-centric view of miRNA action is also reported. Evaluating TGFβ-responsive miRNA expression in trabecular meshwork cells will further our understanding of the important pathways and changes involved in the pathogenesis of glaucoma and could lead to the development of miRNAs as new therapeutic modalities in glaucoma.

Genetic Alchemy unveiled: MicroRNA-mediated gene therapy as the Artisan craft in the battlefront against hepatocellular carcinoma-a comprehensive chronicle of strategies and innovations.

Investigating therapeutic miRNAs is a rewarding endeavour for pharmaceutical companies. Since its discovery in 1993, our understanding of miRNA biology has advanced significantly. Numerous studies have emphasised the disruption of miRNA expression in various diseases, making them appealing candidates for innovative therapeutic approaches. Hepatocellular carcinoma (HCC) is a significant malignancy that poses a severe threat to human health, accounting for approximately 70%-85% of all malignant tumours. Currently, the efficacy of several HCC therapies is limited. Alterations in various biomacromolecules during HCC progression and their underlying mechanisms provide a basis for the investigation of novel and effective therapeutic approaches. MicroRNAs, also known as miRNAs, have been identified in the last 20years and significantly impact gene expression and protein translation. This atypical expression pattern is strongly associated with the onset and progression of various malignancies. Gene therapy, a novel form of biological therapy, is a prominent research area. Therefore, miRNAs have been used in the investigation of tumour gene therapy. This review examines the mechanisms of action of miRNAs, explores the correlation between miRNAs and HCC, and investigates the use of miRNAs in HCC gene therapy.

The Role of MicroRNAs in the Pathophysiology of Osteoarthritis.

Worldwide, osteoarthritis (OA) is the most common cause of joint pain in older people. Many factors contribute to osteoarthritis' development and progression, including secondary osteoarthritis' underlying causes. It is important to note that osteoarthritis affects all four tissues: cartilage, bone, joint capsule, and articular apparatus. An increasingly prominent area of research in osteoarthritis regulation is microRNAs (miRNAs), a small, single-stranded RNA molecule that controls gene expression in eukaryotes. We aimed to assess and summarize current knowledge about the mechanisms of the action of miRNAs and their clinical significance. Osteoarthritis (OA) is affected by the interaction between miRNAs and inflammatory processes, as well as cartilage metabolism. MiRNAs also influence cartilage cell apoptosis, contributing to the degradation of the cartilage in OA. Studies have shown that miRNAs may have both an inhibitory and promoting effect on osteoporosis progression through their influence on molecular mechanisms. By identifying these regulators, targeted treatments for osteoarthritis may be developed. In addition, microRNA may also serve as a biomarker for osteoarthritis. By using these biomarkers, the disease could be detected faster, and early intervention can be instituted to prevent mobility loss and slow deterioration.

Highlighting the role of long non-coding RNA (LncRNA) in multiple myeloma (MM) pathogenesis and response to therapy.

Transcripts longer than 200 nucleotides that are not translated into proteins are known as long non-coding RNAs, or lncRNAs. Now, theyare becoming more significant as important regulators of gene expression, and as a result, of many biological processes in both healthy and pathological circumstances, such as blood malignancies. Through controlling alternative splicing, transcription, and translation at the post-transcriptional level, lncRNAs have an impact on the expression of genes. In multiple myeloma (MM), the majority of lncRNAs is elevated andpromotes the proliferation, adhesion, drug resistance andinvasion of MM cells by blocking apoptosis and altering the tumor microenvironment (TME). To control mRNA splicing, stability, and translation, they either directly attach to the target mRNA or transfer RNA-binding proteins (RBPs). By expressing certain miRNA-binding sites that function as competitive endogenous RNAs (ceRNAs), most lncRNAs mimic the actions of miRNAs. Here, we highlight lncRNAs rolein the MM pathogenesiswith emphasizeon their capacity to control the molecular mechanisms known as "hallmarks of cancer," which permit earlier tumor initiation and progression and malignant cell transformation.

Plasmonics nanorod biosensor for in situ intracellular detection of gene expression biomarkers in intact plant systems

The intracellular developmental processes in plants, particularly concerning lignin polymer formation and biomass production are regulated by microRNAs (miRNAs). MiRNAs including miR397b are important for developing efficient and cost-effective biofuels. However, traditional methods of monitoring miRNA expression, like PCR, are time-consuming, require sample extraction, and lack spatial and temporal resolution, especially in real-world conditions. We present a novel approach using plasmonics nanosensing to monitor miRNA activity within living plant cells without sample extraction. Plasmonic biosensors using surface-enhanced Raman scattering (SERS) detection offer high sensitivity and precise molecular information. We used the Inverse Molecular Sentinel (iMS) biosensor on unique silver-coated gold nanorods (AuNR@Ag) with a high-aspect ratio to penetrate plant cell walls for detecting miR397b within intact living plant cells. MiR397b overexpression has shown promise in reducing lignin content. Thus, monitoring miR397b is essential for cost-effective biofuel generation. This study demonstrates the infiltration of nanorod iMS biosensors and detection of non-native miRNA 397b within plant cells for the first time. The investigation successfully demonstrates the localization of nanorod iMS biosensors through TEM and XRF-based elemental mapping for miRNA detection within plant cells of Nicotiana benthamiana. The study integrates shifted-excitation Raman difference spectroscopy (SERDS) to decrease background interference and enhance target signal extraction. In vivo SERDS testing confirms the dynamic detection of miR397b in Arabidopsis thaliana leaves after infiltration with iMS nanorods and miR397b target. This proof-of-concept study is an important stepping stone towards spatially resolved, intracellular miRNA mapping to monitor biomarkers and biological pathways for developing efficient renewable biofuel sources.

MiRNA-targeting oligonucleotide constructs with various mechanisms of action as effective inhibitors of carcinogenesis

INTRODUCTION. The development of malignant neoplasms is associated with changes in the expression of small non-coding RNAs (miRNAs). This emphasises the need for research into the development of miRNA-targeted inhibitors as a promising approach to cancer treatment.AIM. This study aimed to compare current strategies for suppressing the functional activity of tumour-associated miRNAs based on the use of therapeutic nucleic acids and to determine the application potential of these strategies.DISCUSSION. This study analysed known oligonucleotide-based miRNA inhibitors with different mechanisms of action. Based on their mechanism of action, miRNA-targeted inhibitors can be classified into two groups. The first group of miRNA-targeted inhibitors exhibits an indirect inhibitory effect, either by blocking functional connections between miRNAs and specific mRNA targets through the use of miRNA-masking oligonucleotides or by introducing mutations into miRNA genes and disrupting gene biosynthesis processes through the use of the CRISPR/Cas system. Despite their relatively high biological potential, these strategies are mostly used as search tools to study miRNA functional roles and molecular interactions in carcinogenesis. The second group of oligonucleotide constructs interacts with miRNA targets directly, which leads to steric blocking or degradation of oncogenic microRNAs. These miRNA-binding oligonucleotide constructs come in a variety of structural variants, including miRNA sponges, RNA zippers, antisense oligonucleotides, and miRNases, which demonstrate high therapeutic potential in vitro and in vivo.CONCLUSION. The described analysis of the biological properties, therapeutic potential, and key advantages of the developed miRNA-targeted oligonucleotide constructs helps outline the areas for their potential practical application in cancer treatment.

Nuclear miRNAs: Gene Regulation Activities.

MicroRNAs (miRNAs) are small non-coding RNAs which contribute to the regulation of many physiological and pathological processes. Conventionally, miRNAs perform their activity in the cytoplasm where they regulate gene expression by interacting in a sequence-specific manner with mature messenger RNAs. Recent studies point to the presence of mature miRNAs in the nucleus. This review summarizes current findings regarding the molecular activities of nuclear miRNAs. These molecules can regulate gene expression at the transcriptional level by directly binding DNA on the promoter or the enhancer of regulated genes. miRNAs recruit different protein complexes to these regions, resulting in activation or repression of transcription, through a number of molecular mechanisms. Hematopoiesis is presented as a paradigmatic biological process whereby nuclear miRNAs possess a relevant regulatory role. Nuclear miRNAs can influence gene expression by affecting nuclear mRNA processing and by regulating pri-miRNA maturation, thus impacting the biogenesis of miRNAs themselves. Overall, nuclear miRNAs are biologically active molecules that can be critical for the fine tuning of gene expression and deserve further studies in a number of physiological and pathological conditions.