Inhibition of miR-21 in glioma cells using catalytic nucleic acids

CRISPR targeting of mmu-miR-21a through a single adeno-associated virus vector prolongs survival of glioblastoma-bearing mice

Glioblastoma (GB), the most aggressive tumor of the central nervous system (CNS), has poor patient outcomes with limited effective treatments available. MicroRNA-21 (miR-21(a)) is a known oncogene, abundantly expressed in many cancer types. miR-21(a) promotes GB progression, and lack of miR-21(a) reduces the tumorigenic potential. Here, we propose a single adeno-associated virus (AAV) vector strategy targeting mmu-miR-21a using the Staphylococcus aureus Cas9 ortholog (SaCas9) guided by a single-guide RNA (sgRNA). Our results demonstrate that AAV8 is a well-suited AAV serotype to express SaCas9-KKH/sgRNA at the tumor site in an orthotopic GB model. The SaCas9-KKH induced a genomic deletion, resulting in lowered mmu-miR-21a levels in the brain, leading to reduced tumor growth and improved overall survival. In this study, we demonstrated that disruption of genomic mmu-miR-21a with a single AAV vector influenced glioma development, resulting in beneficial anti-tumor outcomes in GB-bearing mice.

Dual Roles of miR-10a-5p and miR-10b-5p as Tumor Suppressors and Oncogenes in Diverse Cancers

Cancer is a complex genetic disorder characterized by abnormalities in both coding and regulatory non-coding RNAs. microRNAs (miRNAs) are key regulatory non-coding RNAs that modulate cancer development, functioning as both tumor suppressors and oncogenes. miRNAs play critical roles in cancer progression, influencing key processes such as initiation, promotion, and metastasis. They exert their effects by targeting tumor suppressor genes, thereby facilitating cancer progression, while also inhibiting oncogenes to prevent further disease advancement. The miR-10 family, particularly miR-10a-5p and miR-10b-5p (miR-10a/b-5p), is notably involved in cancer progression. Intriguingly, their functions can differ across different cancers, sometimes promoting and at other times suppressing tumor growth depending on the cancer type and target genes. This review explores the dual roles of miR-10a/b-5p as tumor-suppressive miRNAs (TSmiRs) or oncogenic miRNAs (oncomiRs) in various cancers by examining their molecular and cellular mechanisms and their impact on the tumor microenvironment. Furthermore, we discuss the potential of miR-10a/b-5p as therapeutic targets, emphasizing miRNA-based strategies for cancer treatment. The insights discussed in this review aim to advance our understanding of miR-10a/b-5p's roles in tumor biology and their application in developing innovative cancer therapies.

The potential of miRNA-based approaches in glioblastoma: An update in current advances and future perspectives

Glioblastoma (GBM) is the most common malignant central nervous system tumor. The emerging field of epigenetics stands out as particularly promising. Notably, the discovery of micro RNAs (miRNAs) has paved the way for advancements in diagnosing, treating, and prognosticating patients with brain tumors. We aim to provide an overview of the emergence of miRNAs in GBM and their potential role in the multifaceted management of this disease. We discuss the current state of the art regarding miRNAs and GBM. We performed a narrative review using the MEDLINE/PUBMED database to retrieve peer-reviewed articles related to the use of miRNA approaches for the treatment of GBMs. MiRNAs are intrinsic non-coding RNA molecules that regulate gene expression mainly through post-transcriptional mechanisms. The deregulation of some of these molecules is related to the pathogenesis of GBM. The inclusion of molecular characterization for the diagnosis of brain tumors and the advent of less-invasive diagnostic methods such as liquid biopsies, highlights the potential of these molecules as biomarkers for guiding the management of brain tumors such as GBM. Importantly, there is a need for more studies to better examine the application of these novel molecules. The constantly changing characterization and approach to the diagnosis and management of brain tumors broaden the possibilities for the molecular inclusion of novel epigenetic molecules, such as miRNAs, for a better understanding of this disease.

DNAzymes: Expanding the Potential of Nucleic Acid Therapeutics

Nucleic acids drugs have been proven in the clinic as a powerful modality to treat inherited and acquired diseases. However, key challenges including drug stability, renal clearance, cellular uptake, and movement across biological barriers (foremost the blood-brain barrier) limit the translation and clinical efficacy of nucleic acid-based therapies, both systemically and in the central nervous system. In this study we provide an overview of an emerging class of nucleic acid therapeutic, called DNAzymes. In particular, we review the use of chemical modifications and carrier molecules for the stabilization and/or delivery of DNAzymes in cell and animal models. Although this review focuses on DNAzymes, the strategies described are broadly applicable to most nucleic acid technologies. This review should serve as a general guide for selecting chemical modifications to improve the therapeutic performance of DNAzymes.

Targeting non-coding RNA family members with artificial endonuclease XNAzymes

Non-coding RNAs (ncRNAs) offer a wealth of therapeutic targets for a range of diseases. However, secondary structures and high similarity within sequence families make specific knockdown challenging. Here, we engineer a series of artificial oligonucleotide enzymes (XNAzymes) composed of 2'-deoxy-2'-fluoro-β-D-arabino nucleic acid (FANA) that specifically or preferentially cleave individual ncRNA family members under quasi-physiological conditions, including members of the classic microRNA cluster miR-17~92 (oncomiR-1) and the Y RNA hY5. We demonstrate self-assembly of three anti-miR XNAzymes into a biostable catalytic XNA nanostructure, which targets the cancer-associated microRNAs miR-17, miR-20a and miR-21. Our results provide a starting point for the development of XNAzymes as a platform technology for precision knockdown of specific non-coding RNAs, with the potential to reduce off-target effects compared with other nucleic acid technologies.

Structural variants and modifications of hammerhead ribozymes targeting influenza A virus conserved structural motifs

The naturally occurring structure and biological functions of RNA are correlated, which includes hammerhead ribozymes. We proposed new variants of hammerhead ribozymes targeting conserved structural motifs of segment 5 of influenza A virus (IAV) (+)RNA. The variants carry structural and chemical modifications aiming to improve the RNA cleavage activity of ribozymes. We introduced an additional hairpin motif and attempted to select ribozyme-target pairs with sequence features that enable the potential formation of the trans-Hoogsteen interactions that are present in full-length, highly active hammerhead ribozymes. We placed structurally defined guanosine analogs into the ribozyme catalytic core. Herein, the significantly improved synthesis of 2′-deoxy-2′-fluoroarabinoguanosine derivatives is described. The most potent hammerhead ribozymes were applied to chimeric short hairpin RNA (shRNA)-ribozyme plasmid constructs to improve the antiviral activity of the two components. The modified hammerhead ribozymes showed moderate cleavage activity. Treatment of IAV-infected Madin-Darby canine kidney (MDCK) cells with the plasmid constructs resulted in significant inhibition of virus replication. Real-time PCR analysis revealed a significant (80%–88%) reduction in viral RNA when plasmids carriers were used. A focus formation assay (FFA) for chimeric plasmids showed inhibition of virus replication by 1.6–1.7 log₁₀ units, whereas the use of plasmids carrying ribozymes or shRNAs alone resulted in lower inhibition.

Downregulation of miR-21 as a promising strategy to overcome drug resistance in cancer

Despite tremendous achievements in the field of targeted cancer therapy, chemotherapy is still the main treatment option, which is challenged by acquired drug resistance. Various microRNAs are involved in developing drug-resistant cells. miR-21 is one of the first identified miRNAs involved in this process. Here, we conducted a literature review to categorize different mechanisms employed by miR-21 to drive drug resistance. miR-21 targets various genes involved in many pathways that can justify chemoresistance. It alters cancer cell metabolism and facilitates adaptation to the new environment. It also enhances drug detoxification in cancerous cells and increases genomic instability. We also summarized various strategies applied for the inhibition of miR-21 in order to reverse cancer drug resistance. These strategies include the delivery of antagomiRs, miRZip knockdown vectors, inhibitory small molecules, CRISPR-Cas9 technology, catalytic nucleic acids, artificial DNA and RNA sponges, and nanostructures like mesoporous silica nanoparticles, dendrimers, and exosomes. Furthermore, current challenges and limitations in targeting miR-21 are discussed in this article. Although huge progress has been made in the downregulation of miR-21 in drug-resistant cancer cells, there are still many challenges to be resolved. More research is still required to find the best strategy and timeline for the downregulation of miR-21 and also the most feasible approach for the delivery of this system into the tumor cells. In conclusion, downregulation of miR-21 would be a promising strategy to reverse chemoresistance, but still, more studies are required to clarify the aforementioned issues.

Exosome-based strategies for diagnosis and therapy of glioma cancer

Glioblastoma belongs to the most aggressive type of cancer with a low survival rate that is characterized by the ability in forming a highly immunosuppressive tumor microenvironment. Intercellular communication are created via exosomes in the tumor microenvironment through the transport of various biomolecules. They are primarily involved in tumor growth, differentiation, metastasis, and chemotherapy or radiation resistance. Recently several studies have highlighted the critical role of tumor-derived exosomes against immune cells. According to the structural and functional properties, exosomes could be essential instruments to gain a better molecular mechanism for tumor understanding. Additionally, they are qualified as diagnostic/prognostic markers and therapeutic tools for specific targeting of invasive tumor cells such as glioblastomas. Due to the strong dependency of exosome features on the original cells and their developmental status, it is essential to review their critical modulating molecules, clinical relevance to glioma, and associated signaling pathways. This review is a non-clinical study, as the possible role of exosomes and exosomal microRNAs in glioma cancer are reported. In addition, their content to overcome cancer resistance and their potential as diagnostic biomarkers are analyzed.

Liquid Biopsy in Glioblastoma Management: From Current Research to Future Perspectives

Glioblastoma (GBM) is the most common primary tumor of the central nervous system. Arising from neuroepithelial glial cells, GBM is characterized by invasive behavior, extensive angiogenesis, and genetic heterogeneity that contributes to poor prognosis and treatment failure. Currently, there are several molecular biomarkers available to aid in diagnosis, prognosis, and predicting treatment outcomes; however, all require the biopsy of tumor tissue. Nevertheless, a tissue sample from a single location has its own limitations, including the risk related to the procedure and the difficulty of obtaining longitudinal samples to monitor treatment response and to fully capture the intratumoral heterogeneity of GBM. To date, there are no biomarkers in blood or cerebrospinal fluid for detection, follow-up, or prognostication of GBM. Liquid biopsy offers an attractive and minimally invasive solution to support different stages of GBM management, assess the molecular biology of the tumor, identify early recurrence and longitudinal genomic evolution, predict both prognosis and potential resistance to chemotherapy or radiotherapy, and allow patient selection for targeted therapies. The aim of this review is to describe the current knowledge regarding the application of liquid biopsy in glioblastoma, highlighting both benefits and obstacles to translation into clinical care. IMPLICATIONS FOR PRACTICE: To translate liquid biopsy into clinical practice, further prospective studies are required with larger cohorts to increase specificity and sensitivity. With the ever-growing interest in RNA nanotechnology, microRNAs may have a therapeutic role in brain tumors.

Targeting Non-coding RNA for Glioblastoma Therapy: The Challenge of Overcomes the Blood-Brain Barrier

Glioblastoma (GBM) is the most malignant form of all primary brain tumors, and it is responsible for around 200,000 deaths each year worldwide. The standard therapy for GBM treatment includes surgical resection followed by temozolomide-based chemotherapy and/or radiotherapy. With this treatment, the median survival rate of GBM patients is only 15 months after its initial diagnosis. Therefore, novel and better treatment modalities for GBM treatment are urgently needed. Mounting evidence indicates that non-coding RNAs (ncRNAs) have critical roles as regulators of gene expression. Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) are among the most studied ncRNAs in health and disease. Dysregulation of ncRNAs is observed in virtually all tumor types, including GBMs. Several dysregulated miRNAs and lncRNAs have been identified in GBM cell lines and GBM tumor samples. Some of them have been proposed as diagnostic and prognostic markers, and as targets for GBM treatment. Most ncRNA-based therapies use oligonucleotide RNA molecules which are normally of short life in circulation. Nanoparticles (NPs) have been designed to increase the half-life of oligonucleotide RNAs. An additional challenge faced not only by RNA oligonucleotides but for therapies designed for brain-related conditions, is the presence of the blood-brain barrier (BBB). The BBB is the anatomical barrier that protects the brain from undesirable agents. Although some NPs have been derivatized at their surface to cross the BBB, optimal NPs to deliver oligonucleotide RNA into GBM cells in the brain are currently unavailable. In this review, we describe first the current treatments for GBM therapy. Next, we discuss the most relevant miRNAs and lncRNAs suggested as targets for GBM therapy. Then, we compare the current drug delivery systems (nanocarriers/NPs) for RNA oligonucleotide delivery, the challenges faced to send drugs through the BBB, and the strategies to overcome this barrier. Finally, we categorize the critical points where research should be the focus in order to design optimal NPs for drug delivery into the brain; and thus move the Oligonucleotide RNA-based therapies from the bench to the clinical setting.

A Trojan-Horse Strategy by In Situ Piggybacking onto Endogenous Albumin for Tumor-Specific Neutralization of Oncogenic MicroRNA

MicroRNAs (miRNAs), a recently discovered class of noncoding RNAs, play pivotal roles in regulating fundamental biological processes by suppressing the expression of target genes. Aberrant miRNA expression is commonly correlated with human diseases, including cancers. Anti-miRNA oligonucleotides provide an innovative therapeutic strategy for silencing disease-associated miRNAs. However, the clinical application of anti-miRNA therapy has been limited by formulation challenges and physiological delivery barriers. Here, to provide the safe and effective tumor-targeted delivery of anti-miRNAs, we designed carrier-free maleimide-functionalized anti-miRNAs (MI-Anti-miRNAs) that enable "piggybacking" onto albumin in vivo. These functionalized MI-Anti-miRNAs covalently bind to cysteine-34 of endogenous albumin within minutes. In addition to resulting in a markedly extended blood circulation lifetime, this strategy allows MI-Anti-miRNAs to "hitchhike" to the tumor site. Importantly, in situ-generated albumin-Anti-miRNAs are capable of intracellularly internalizing highly negatively charged anti-miRNA molecules and knocking down target miRNAs. In particular, MI-Anti-miRNAs that targeted miRNA-21, which is involved in tumor initiation, progression, invasion, and metastasis in several types of cancer, successfully repressed miRNA-21 activity, resulting in a superior antitumor activity in both solid and metastatic tumor models without causing systemic toxicity. This endogenous albumin-piggybacking approach using MI-Anti-miRNAs provides a simple and broadly applicable platform strategy for the systemic delivery of anti-miRNA therapeutics.

Pathogenetic Features and Current Management of Glioblastoma

Glioblastoma (GBM) is the most common form of primary malignant brain tumor with a devastatingly poor prognosis. The disease does not discriminate, affecting adults and children of both sexes, and has an average overall survival of 12-15 months, despite advances in diagnosis and rigorous treatment with chemotherapy, radiation therapy, and surgical resection. In addition, most survivors will eventually experience tumor recurrence that only imparts survival of a few months. GBM is highly heterogenous, invasive, vascularized, and almost always inaccessible for treatment. Based on all these outstanding obstacles, there have been tremendous efforts to develop alternative treatment options that allow for more efficient targeting of the tumor including small molecule drugs and immunotherapies. A number of other strategies in development include therapies based on nanoparticles, light, extracellular vesicles, and micro-RNA, and vessel co-option. Advances in these potential approaches shed a promising outlook on the future of GBM treatment. In this review, we briefly discuss the current understanding of adult GBM's pathogenetic features that promote treatment resistance. We also outline novel and promising targeted agents currently under development for GBM patients during the last few years with their current clinical status.

The role of MiRNA-21 in gliomas: Hope for a novel therapeutic intervention?

Gliomas are the most common primary brain tumors in adults. They are generally very resistant to treatment and are therefore associated with negative outcomes. MicroRNAs (miRNAs) are small, non-coding RNA molecules that affect many cellular processes by regulating gene expression and, post-transcriptionally, the translation of mRNAs. MiRNA-21 has been consistently shown to be upregulated in glioma and research has shown that it is involved in a wide variety of biological pathways, promoting tumor cell survival and invasiveness. Furthermore, it has been implicated in resistance to treatment, both against chemotherapy and radiotherapy. In this review, we gathered the existent data on miRNA-21 and gliomas, in terms of its expression levels, association with grade and prognosis, the pathways it involves and its targets in glioma, and finally how it leads to treatment resistance. Furthermore, we discuss how this knowledge could be applied in clinical practice in the years to come. To our knowledge, this is the first review to assess in extent and depth the role of miRNA-21 in gliomas.

Glioblastoma-Associated Microglia Reprogramming Is Mediated by Functional Transfer of Extracellular miR-21

Gliomas are primary, diffusely infiltrating brain tumors. Microglia are innate immune cells in the CNS and make up a substantial portion of the tumor mass. Glioma cells shape their microenvironment, communicating with and reprogramming surrounding cells, resulting in enhanced angiogenesis, immune suppression, and remodeling of the extracellular matrix. Glioma cells communicate with microglia, in part by releasing extracellular vesicles (EVs). Mouse glioma cells stably expressing a palmitoylated GFP to label EVs were implanted intracranially into syngeneic miR-21-null mice. Here, we demonstrate functional delivery of miR-21, regulating specific downstream mRNA targets in microglia after uptake of tumor-derived EVs. These findings attest to EV-dependent microRNA delivery as studied in an in vivo-based model and provide insight into the reprograming of microglial cells by tumor cells to create a favorable microenvironment for cancer progression.

Role of exosomes in malignant glioma: microRNAs and proteins in pathogenesis and diagnosis

Malignant gliomas are the most common and deadly type of central nervous system tumors. Despite some advances in treatment, the mean survival time remains only about 1.25 years. Even after surgery, radiotherapy and chemotherapy, gliomas still have a poor prognosis. Exosomes are the most common type of extracellular vesicles with a size range of 30 to 100 nm, and can act as carriers of proteins, RNAs, and other bioactive molecules. Exosomes play a key role in tumorigenesis and resistance to chemotherapy or radiation. Recent evidence has shown that exosomal microRNAs (miRNAs) can be detected in the extracellular microenvironment, and can also be transferred from cell to cell via exosome secretion and uptake. Therefore, many recent studies have focused on exosomal miRNAs as important cellular regulators in various physiological and pathological conditions. A variety of exosomal miRNAs have been implicated in the initiation and progression of gliomas, by activating and/or inhibiting different signaling pathways. Exosomal miRNAs could be used as therapeutic agents to modulate different biological processes in gliomas. Exosomal miRNAs derived from mesenchymal stem cells could also be used for glioma treatment. The present review summarizes the exosomal miRNAs that have been implicated in the pathogenesis, diagnosis and treatment of gliomas. Moreover, exosomal proteins could also be involved in glioma pathogenesis. Exosomal miRNAs and proteins could also serve as non-invasive biomarkers for prognosis and disease monitoring. Video Abstract.

Potential Therapeutic Effects of Exosomes Packed With a miR-21-Sponge Construct in a Rat Model of Glioblastoma

Glioblastoma multiforme (GBM) is a grade 4 and the most aggressive form of glioma, with a poor response to current treatments. The expression of microRNAs (miRNAs) is widely dysregulated in various cancers, including GBM. One of the overexpressed miRNAs in GBM is miR-21 which promotes proliferation, invasion and metastatic behaviors of tumor cells. With a size of 30-100 nm, the extracellular vesicles "exosomes" have emerged as a novel and powerful drug delivering systems. Recently, exosomal transfer of miRNAs or anti-miRNAs to tumor cells has introduced a new approach for therapeutic application of miRNAs to combat cancer. Here, we have tried to down-regulate miR-21 expression in glioma cell lines, U87-MG, and C6, by using engineered exosomes, packed with a miR-21-sponge construct. Our data revealed that the engineered exosomes have the potential to suppress miR-21 and consequently to upregulate miR-21 target genes, PDCD4 and RECK. Interestingly, in cells treated with miR-21-sponge exosomes we observed a decline in proliferation and also an elevation in apoptotic rates. Finally, in a rat model of glioblastoma, administrating exosomes loaded with a miR-21-sponge construct leads to a significant reduction in the volume of the tumors. In brief, our findings suggest a new therapeutic strategy to use engineered exosomes to deliver a miR-21-sponge construct to GBM cells, in order to block its malignant behavior.

Development of Novel antimiRzymes for Targeted Inhibition of miR-21 Expression in Solid Cancer Cells

MicroRNAs (miRNAs) are short non-coding RNAs that are involved in the regulation of gene expression. Previous reports showed an over-expression of miRNA-21 (miR-21) in various cancer cells, and its up-regulation is closely related to cancer initiation, proliferation and metastasis. In this work, we envisioned the development of novel antimiRzymes (anti-miRNA-DNAzyme) that are capable of selectively targeting and cleaving miR-21 and inhibit its expression in cancer cells using the DNAzyme technique. For this purpose, we have designed different antimiRzyme candidates by systematically targeting different regions of miR-21. Our results demonstrated that RNV541, a potential arm-loop-arm type antimiRzyme, was very efficient (90%) to suppress miR-21 expression in U87MG malignant glioblastoma cell line at 200 nM concentration. In addition, RNV541 also inhibited miR-21 expression (50%) in MDA-MB-231 breast cancer cell line. For targeted delivery, we conjugated RNV541 with a transferrin receptor (TfR) targeting aptamer for TfR-mediated cancer cell delivery. As expected, the developed chimeric structure efficiently delivered the antimiRzyme RNV541 into TfR positive glioblastoma cells. TfR aptamer-RNV541 chimeric construct showed 52% inhibition of miR-21 expression in U87MG glioblastoma cells at 2000 nM concentration, without using any transfection reagents, making it a highly desirable strategy to tackle miR-21 over-expressed malignant cancers. Although these are in vitro based observations, based on our results, we firmly believe that our findings could be beneficial towards the development of targeted cancer therapeutics where conventional therapies face several challenges.

MicroRNAs in Microglia: How do MicroRNAs Affect Activation, Inflammation, Polarization of Microglia and Mediate the Interaction Between Microglia and Glioma?

The essential roles of microglia in maintaining homeostasis in the healthy brain and contributing to neuropathology are well documented. Emerging evidence suggests that epigenetic modulation regulates microglial behavior in both physiological and pathological conditions. MicroRNAs (miRNAs) are short, non-coding epigenetic regulators that repress target gene expression mostly via binding to 3'-untranslated region (3'-UTR) of mRNA in a Dicer-dependent manner. Dysregulation of certain miRNAs can contribute to microglial hyper-activation, persistent neuroinflammation, and abnormal macrophage polarization in the brain. These abnormal conditions can support the pathogenesis of neurological disorders such as glioma, Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), stroke, ischemia, and spinal cord injury (SCI). However, the roles of miRNAs in microglia in health and neurological disease have not been systematically summarized. This review will first report the role of Dicer, a key endoribonulease that is responsible for most miRNA biogenesis in microglia. Second, we will focus on recent research about the function of miRNAs in activation, inflammation and polarization of microglia, respectively. In addition, potential crosstalk between microglia and glioma cells via miRNAs will be discussed in this part. Finally, the role of two essential miRNAs, miR-124, and miR-155, in microglia will be highlighted.

Molecular Engineering of Functional Nucleic Acid Nanomaterials toward In Vivo Applications

Recent advances in nanotechnology and engineering have generated many nanomaterials with unique physical and chemical properties. Over the past decade, numerous nanomaterials are introduced into many research areas, such as sensors for environmental monitoring, food safety, point-of-care diagnostics, and as transducers for solar energy transfer. Meanwhile, functional nucleic acids (FNAs), including nucleic acid enzymes, aptamers, and aptazymes, have attracted major attention from the biomedical community due to their unique target recognition and catalytic properties. Benefiting from the recent progress of molecular engineering strategies, the physicochemical properties of nanomaterials are endowed by the target recognition and catalytic activity of FNAs in the presence of a target analyte, resulting in numerous smart nanoprobes for diverse applications including intracellular imaging, drug delivery, in vivo imaging, and tumor therapy. This progress report focuses on the recent advances in designing and engineering FNA-based nanomaterials, highlighting the functional outcomes toward in vivo applications. The challenges and opportunities for the future translation of FNA-based nanomaterials into clinical applications are also discussed.

RNA-Cleaving DNAzymes: Old Catalysts with New Tricks for Intracellular and In Vivo Applications

DNAzymes are catalytically active DNA molecules that are normally isolated through in vitro selection methods, among which RNA-cleaving DNAzymes that catalyze the cleavage of a single RNA linkage embedded within a DNA strand are the most studied group of this DNA enzyme family. Recent advances in DNA nanotechnology and engineering have generated many RNA-cleaving DNAzymes with unique recognition and catalytic properties. Over the past decade, numerous RNA-cleaving, DNAzymes-based functional probes have been introduced into many research areas, such as in vitro diagnostics, intracellular imaging, and in vivo therapeutics. This review focus on the fundamental insight into RNA-Cleaving DNAzymes and technical tricks for their intracellular and in vivo applications, highlighting the recent progress in the clinical trial of RNA-Cleaving DNAzymes with selected examples. The challenges and opportunities for the future translation of RNA-cleaving DNAzymes for biomedicine are also discussed.

Expression of microRNA-184 in glioma

The aim of the present study was to examine the expression of microRNA (miRNA)-184 in gliomas with different pathological grades, and its effect on survival prognosis. For the present study, 40 participants were selected with different pathological grades of glioma tissues with grade I (n=10), grade II (n=8), grade III (n=16), and grade IV (n=6). In addition, 10 cases of normal brain tissue (obtained by decompression because of traumatic brain injury) were selected. RT-PCR and immunohistochemical techniques were used to detect the expression level and intensity of miRNA-184 in different grades of glioma tissues. The length of survival of miRNA-184-positive patients was analyzed. miRNA-184 mRNA expression was found in normal tissues and tumor tissues, and the expression in tumor tissues was significant (P<0.05). Statistically significant differences of miRNA-184 expression were observed among different grades (P<0.05). miRNA-184 expression increased with the increase of grade level. The differences in expression across grade levels was statistically significant (P<0.05). A positive expression was not related to the pathological types of glioma cells. The median survival time of patients with miRNA-184-positive expression was significantly shorter than that of the negative expression group (P<0.05). miRNA-184 is highly expressed in gliomas, which is positively correlated with pathological grade, and is not correlated with pathological type, and negatively correlated with survival time. Thus, miRNA-184 is a potentially important molecular marker for glioma.

MiR-21: A key player in glioblastoma pathogenesis

Glioblastoma multiform (GBM) is one of common cancers worldwide which has high rate among various populations. Despite serious efforts worldwide, GBM remains a deadly disease which is associated with poor prognosis. Multiple lines evidence indicated that deregulation of a variety of cellular and molecular pathways are related with GBM pathogenesis. Among of various targets involved in GBM pathogenesis, microRNAs (miRNAs) have been emerged as targets which deregulation of them are related with various stages of GBM. These molecules are small non-coding RNAs which could affect on a variety of cellular and molecular pathways involved in GBM. It has been showed that deregulation of them are associated with initiation and progression of GBM. MiR-21 is one of important miRNAs involved in GBM pathogenesis. A large number studies indicated that this miRNA could affect on a variety of cellular and molecular pathways such as insulin-like growth factor (IGF)-binding protein-3 (IGFBP3), RECK, and TIMP3. Exosomes are one of important players in GBM pathogenesis. Among of various exosomes, exosomal miR-21 may has key roles in GBM pathogenesis. These findings indicated that miR-21 has critical roles in GBM pathogenesis and could be used as diagnostic and therapeutic biomarkers for GBM patients. Here, we summarized the roles of miR-21 and exosomal miR-21 in GBM pathogenesis. Moreover, we highlighted utilization of miR-21 as diagnostic and therapeutic biomarker for GBM patients.

An Insight into the Increasing Role of LncRNAs in the Pathogenesis of Gliomas

Long non-coding RNAs (LncRNAs) are essential epigenetic regulators with critical roles in tumor initiation and malignant progression. However, the roles and mechanisms of aberrantly expressed lncRNAs in the pathogenesis of gliomas are not fully understood. With the development of deep sequencing analyses, an extensive amount of functional non-coding RNAs has been discovered in glioma tissues and cell lines. Additionally, the contributions of several lncRNAs, such as Hox transcript antisense intergenic RNA, H19 and Colorectal neoplasia differentially expressed, previously reported to be involved in other pathogenesis and processes to the oncogenesis of glioblastoma are currently addressed. Thus, lncRNAs detected in tumor tissues could serve as candidate diagnostic biomarkers and therapeutic targets for gliomas. To understand the potential function of lncRNAs in gliomas, in this review, we briefly describe the profile of lncRNAs in human glioma research and therapy. Then, we discuss the individual lncRNA that has been under intensive investigation in glioma research, and the focus is its mechanism and clinical implication.