MicroRNAs as biomarkers for CNS cancer and other disorders

Circulating microRNAs: A remarkable opportunity as non-invasive biomarkers from adult to pediatric brain tumor patients

Central nervous system (CNS) tumors represent the most frequent solid tumors among adolescents and children, and the leading cause of cancer-related death in men < 40 and women < 20 years of age. Brain tumors are challenging to diagnose, monitor, and treat. The current diagnostic approach involves magnetic resonance imaging (MRI), tumor histology, molecular characterization and cytologic analysis of cerebrospinal fluid (CSF). However, surgical procedures pose potential risks to the patient's health, not achieving good accuracy. For these reasons, it is crucial to identify new non-invasive disease biomarkers to improve patients' stratification at diagnosis and during follow-up and prognosis. MicroRNAs (miRNAs) are a class of short RNA molecules that have been demonstrated in numerous studies to be dysregulated in brain tumor patients. As a result, they may be used as biomarkers of brain tumors. Additionally, miRNAs can be analyzed in liquid biopsy samples, such as blood and CSF, providing a non-invasive source of biomolecular data on patients' disease status. This review aims to highlight the role of miRNAs in liquid biopsy, also known as circulating miRNAs, as potential non-invasive cancer biomarkers in both adult and pediatric populations and to suggest their potential impact on clinical trials.

The foam cell-derived exosomal miRNA Novel-3 drives neuroinflammation and ferroptosis during ischemic stroke

Large artery atherosclerosis (LAA) is a prevalent cause of acute ischemic stroke (AIS). Understanding the mechanisms linking atherosclerosis to stroke is essential for developing appropriate intervention strategies. Here, we found that the exosomal miRNA Novel-3 is selectively upregulated in the plasma of patients with LAA-AIS. Notably, Novel-3 was predominantly expressed in macrophage-derived foam cells, and its expression correlated with atherosclerotic plaque vulnerability in patients undergoing carotid endarterectomy. Exploring the function of Novel-3 in a mouse model of cerebral ischemia, we found that Novel-3 exacerbated ischemic injury and targeted microglia and macrophages expressing ionized calcium-binding adapter molecule 1 in peri-infarct regions. Mechanistically, Novel-3 increased ferroptosis and neuroinflammation by interacting with striatin (STRN) and downregulating the phosphoinositide 3-kinase-AKT-mechanistic target of rapamycin signaling pathway. Blocking Novel-3 activity or overexpressing STRN provided neuroprotection under ischemic conditions. Our findings suggest that exosomal Novel-3, which is primarily derived from macrophage-derived foam cells, targets microglia and macrophages in the brain to induce neuroinflammation and could serve as a potential therapeutic target for patients with stroke who have atherosclerosis.

Unveiling new chapters in medullary thyroid carcinoma therapy: advances in molecular genetics and targeted treatment strategies

Medullary Thyroid Carcinoma (MTC), a neuroendocrine malignancy that arises from the calcitonin-secreting parafollicular C-cells of the thyroid, constitutes a minor yet impactful fraction of thyroid malignancies. Distinguished by its propensity for aggressive growth and a pronounced tendency for metastasis, MTC poses formidable obstacles to the early diagnosis and therapeutic intervention. The molecular genetics of MTC, particularly the role of the RET gene and the RAS gene family, have been extensively studied, offering insights into the pathogenesis of the disease and revealing potential therapeutic targets. This comprehensive review synthesizes the latest advancements in the molecular genetics of MTC, the evolution of precision therapies, and the identification of novel biomarkers. We also discuss the implications of these findings for clinical practice and the future direction of MTC research.

The Role of MicroRNAs in HIV Infection

MicroRNAs (miRNAs), a class of small, non-coding RNAs, play a pivotal role in regulating gene expression at the post-transcriptional level. These regulatory molecules are integral to many biological processes and have been implicated in the pathogenesis of various diseases, including Human Immunodeficiency Virus (HIV) infection. This review aims to cover the current understanding of the multifaceted roles miRNAs assume in the context of HIV infection and pathogenesis. The discourse is structured around three primary focal points: (i) elucidation of the mechanisms through which miRNAs regulate HIV replication, encompassing both direct targeting of viral transcripts and indirect modulation of host factors critical for viral replication; (ii) examination of the modulation of miRNA expression by HIV, mediated through either viral proteins or the activation of cellular pathways consequent to viral infection; and (iii) assessment of the impact of miRNAs on the immune response and the progression of disease in HIV-infected individuals. Further, this review delves into the potential utility of miRNAs as biomarkers and therapeutic agents in HIV infection, underscoring the challenges and prospects inherent to this line of inquiry. The synthesis of current evidence positions miRNAs as significant modulators of the host-virus interplay, offering promising avenues for enhancing the diagnosis, treatment, and prevention of HIV infection.

Salivary miRNAs as auxiliary liquid biopsy biomarkers for diagnosis in patients with oropharyngeal squamous cell carcinoma: a systematic review and meta-analysis

Objective: The healthcare system needs a novel approach to improve and diagnose early oropharyngeal squamous cell carcinoma against its low survival rate. We conduct a systematic review and a comprehensive meta-analysis for the diagnostic role of blood and salivary microRNAs (miRNAs). Methods: An unbiased and thorough literature search in PubMed yielded appropriate data from qualified articles regarding different miRNA biomarkers, method of extraction, research location, and year of publication. Stata was used to calculate the sensitivity, specificity, diagnostic odds ratio, and summary receiver operating characteristic curve. Results: We included 9 studies with 399 qualified oropharyngeal squamous cell carcinoma patients, which yielded a high diagnostic accuracy of blood miRNAs in combination with salivary miRNAs with a sensitivity of 0.70 (p < 0.001), specificity of 0.75 (p = 0.26), diagnostic odds ratio of 7, and an area under the curve of 0.78. Conclusion: Combined blood- and saliva-derived miRNAs demonstrated a high diagnostic accuracy in detecting oropharyngeal squamous cell carcinoma. Systematic review registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42024509424.

miRNAs: Targets to Investigate Herpesvirus Infection Associated with Neurological Disorders

Herpesvirus is associated with various neurological disorders and a specific diagnosis is associated with a better prognosis. MicroRNAs (miRNAs) are potential diagnostic and prognostic biomarkers of neurological diseases triggered by herpetic infection. In this review, we discuss miRNAs that have been associated with neurological disorders related to the action of herpesviruses. Human miRNAs and herpesvirus-encoded miRNAs were listed and discussed. This review article will be valuable in stimulating the search for new diagnostic and prognosis alternatives and understanding the role of these miRNAs in neurological diseases triggered by herpesviruses.

Blood exosome sensing via neuronal insulin-like growth factor-1 regulates autism-related phenotypes

The development and progression of autism spectrum disorder (ASD) is characterized by multiple complex molecular events, highlighting the importance of the prefrontal brain regions in this process. Exosomes are nanovesicles that play a critical role in intercellular communication. Peripheral systems influence brain function under both physiological and pathological conditions. We investigated whether this influence was mediated by the direct sensing of peripheral blood exosomes by brain cells. Administration of serum exosomes from rats with valproic acid-induced ASD resulted in ASD-related phenotypes in mice, whereas exosomes from normal rats did not exhibit such effects. RNA sequencing and bioinformatics analysis suggested that negative regulation of medial prefrontal cortex (mPFC) insulin-like growth factor 1 (IGF-1) by exosome-derived miR-29b-3p may contribute to these ASD-associated effects. Further evidence showed that miR-29b-3p-enriched exosomes crossed the blood-brain barrier to reach the mPFC, subsequently inducing the suppression of IGF-1 expression in neurons. Optogenetic activation of excitatory neurons in the mPFC improved behavioral abnormalities in exosome-treated mice. The addition of exogenous IGF-1 or inhibition of miR-29b-3p expression in the mPFC also rescued the ASD-related phenotypes in mice. Importantly, administration of miR-29b-3p-enriched serum exosomes from human donors with ASD into the mouse medial prefrontal cortex was sufficient to induce hallmark ASD behaviors. Together, our findings indicate that blood-brain cross-talk is crucial for ASD pathophysiology and that the brain may sense peripheral system changes through exosomes, which could serve as the basis for future neurological therapies.

MicroRNAs in Parkinson's disease: a systematic review and diagnostic accuracy meta-analysis

Current clinical tests for Parkinson's disease (PD) provide insufficient diagnostic accuracy leading to an urgent need for improved diagnostic biomarkers. As microRNAs (miRNAs) are promising biomarkers of various diseases, including PD, this systematic review and meta-analysis aimed to assess the diagnostic accuracy of biofluid miRNAs in PD. All studies reporting data on miRNAs expression in PD patients compared to controls were included. Gene targets and significant pathways associated with miRNAs expressed in more than 3 biofluid studies with the same direction of change were analyzed using target prediction and enrichment analysis. A bivariate model was used to calculate sensitivity, specificity, likelihood ratios, and diagnostic odds ratio. While miR-24-3p and miR-214-3p were the most reported miRNA (7 each), miR-331-5p was found to be consistently up regulated in 4 different biofluids. Importantly, miR-19b-3p, miR-24-3p, miR-146a-5p, and miR-221-3p were reported in multiple studies without conflicting directions of change in serum and bioinformatic analysis found the targets of these miRNAs to be associated with pathways important in PD pathology. Of the 102 studies from the systematic review, 15 studies reported sensitivity and specificity data on combinations of miRNAs and were pooled for meta-analysis. Studies (17) reporting sensitivity and specificity data on single microRNA were pooled in a separate meta-analysis. Meta-analysis of the combinations of miRNAs (15 studies) showed that biofluid miRNAs can discriminate between PD patients and controls with good diagnostic accuracy (sensitivity = 0.82, 95% CI 0.76-0.87; specificity = 0.80, 95% CI 0.74-0.84; AUC = 0.87, 95% CI 0.83-0.89). However, we found multiple studies included more males with PD than any other group therefore possibly introducing a sex-related selection bias. Overall, our study captures key miRNAs which may represent a point of focus for future studies and the development of diagnostic panels whilst also highlighting the importance of appropriate study design to develop representative biomarker panels for the diagnosis of PD.

Glimepiride Compared to Liraglutide Increases Plasma Levels of miR-206, miR-182-5p, and miR-766-3p in Type 2 Diabetes Mellitus: A Randomized Controlled Trial

BACKGRUOUND

Diabetes is a chronic disease with several long-term complications. Several glucose-lowering drugs are used to treat type 2 diabetes mellitus (T2DM), e.g., glimepiride and liraglutide, in which both having different modes of action. Circulating microRNAs (miRNAs) are suggested as potential biomarkers that are associated with the disease development and the effects of the treatment. In the current study we evaluated the effect of glimepiride, liraglutide on the expression of the circulating miRNAs.

METHODS

The present study is a post hoc trial from a previously randomized control trial comparing liraglutide versus glimepiride both in combination with metformin in subjects with T2DM, and subclinical heart failure. miRNAs were determined in the subjects' serum samples with next generation sequencing. Expression patterns of the circulating miRNAs were analyzed using bioinformatic univariate and multivariate analyses (clinical trial registration: NCT01425580).

RESULTS

Univariate analyses show that treatment with glimepiride altered expression of three miRNAs in patient serum, miR-206, miR-182-5p, and miR-766-3p. Both miR-182-5p and miR-766-3p were also picked up among the top contributing miRNAs with penalized regularised logistic regressions (Lasso). The highest-ranked miRNAs with respect to Lasso coefficients were miR-3960, miR-31-5p, miR-3613-3p, and miR-378a-3p. Liraglutide treatment did not significantly influence levels of circulating miRNAs.

CONCLUSION

Present study indicates that glucose-lowering drugs differently affect the expression of circulating miRNAs in serum in individuals with T2DM. More studies are required to investigate possible mechanisms by which glimepiride is affecting the expression of circulating miRNAs.

miRNAs in Neurological Manifestation in Patients Co-Infected with SARS-CoV-2 and Herpesvírus 6 (HHV-6)

Human herpesviruses (HHVs) can establish latency and be reactivated, also are neurotropic viruses that can trigger neurological disorders. HHV-6 is a herpesvirus that is associated with neurological disorders. Studies have reported the detection of HHV-6 in patients with COVID-19 and neurological manifestations. However, specific diagnoses of the neurological disorders caused by these viruses tend to be invasive or difficult to interpret. This study aimed to establish a relationship between miRNA and neurological manifestations in patients co-infected with COVID-19 and HHV-6 and evaluate miRNAs as potential biomarkers. Serum samples from COVID-19 patients in the three cohorts were analyzed. miRNA analysis by real-time polymerase chain reaction (qPCR) revealed miRNAs associated with neuroinflammation were highly expressed in patients with neurological disorders and HHV-6 detection. When compared with the group of patients without detection of HHVs DNA and without neurological alterations, the group with detection of HHV-6 DNA and neurological alteration, displayed significant differences in the expression of mir-21, mir-146a, miR-155 and miR-let-7b (p < 0.01). Our results reinforce the involvement of miRNAs in neurological disorders and provide insights into their use as biomarkers for neurological disorders triggered by HHV-6. Furthermore, understanding the expression of miRNAs may contribute to therapeutic strategies.

Genome-wide post-transcriptional regulation of bovine mammary gland response to Streptococcus uberis

MicroRNAs (miRNAs) as post-transcriptionally regulators of gene expression have been shown to be critical regulators to fine-tuning immune responses, besides their criteria for being an ideal biomarker. The regulatory role of miRNAs in responses to most mastitis-causing pathogens is not well understood. Gram-positive Streptococcus uberis (Str. uberis), the leading pathogen in dairy herds, cause both clinical and subclinical infections. In this study, a system biology approach was used to better understand the main post-transcriptional regulatory functions and elements of bovine mammary gland response to Str. uberis infection. Publicly available miRNA-Seq data containing 50 milk samples of the ten dairy cows (five controls and five infected) were retrieved for this current research. Functional enrichment analysis of predicted targets revealed that highly confident responsive miRNAs (4 up- and 19 downregulated) mainly regulate genes involved in the regulation of transcription, apoptotic process, regulation of cell adhesion, and pro-inflammatory signaling pathways. Time series analysis showed that six gene clusters significantly differed in comparisons between Str. uberis-induced samples with controls. Additionally, other bioinformatic analysis, including upstream network analysis, showed essential genes, including TP53 and TGFB1 and some small molecules, including glucose, curcumin, and LPS, commonly regulate most of the downregulated miRNAs. Upregulated miRNAs are commonly controlled by the most important genes, including IL1B, NEAT1, DICER1 enzyme and small molecules including estradiol, tamoxifen, estrogen, LPS, and epigallocatechin. Our study used results of next-generation sequencing to reveal key miRNAs as the main regulator of gene expression responses to a Gram-positive bacterial infection. Furthermore, by gene regulatory network (GRN) analysis, we can introduce the common upregulator transcription factor of these miRNAs. Such milk-based miRNA signature(s) would facilitate risk stratification for large-scale prevention programs and provide an opportunity for early diagnosis and therapeutic intervention.

The Role of MicroRNA 181d as a Possible Biomarker Associated With Tumor Progression in Meningiomas

Introduction

Meningiomas are slow-growing intracranial neoplasms that originate from arachnoid meningothelial cells and represent 13-26% of intracranial tumors, thus being the most common. There are numerous technological advances available for a better understanding of the molecular pathways correlated with tumorigenesis and tumor progression of meningiomas. In this context, the role of microRNAs (miRNAs), which are non-coding RNAs (ncRNAs) consisting of 18 to 25 nucleotides whose function is the silencing of mRNA at the posttranscriptional level, has been highlighted. Recent studies suggest that miRNAs may act as possible biomarkers as well as therapeutic targets for various diseases, including brain tumors. Therefore, the objective of our study was to evaluate the tissue and plasma expression of the miRNAs miR-181d, miR-181c, and miR-130a.

Methods

The miRNAs miR-181d, miR-181c, and miR-130a were selected from our group’s prior study by the large-scale microarray analysis technique. In this work, the expression of these miRNAs in the tumor tissue and plasma of patients with grade I (16 patients), II (16 patients), and III (eight patients) meningiomas was evaluated.

Results

MiR-181d was overexpressed in both tumor tissue and plasma in the studied groups. The level of expression was higher according to the progression of tumor grade. MiR-181c and miR-130a showed no significant difference in the studied groups in either tumor tissue or plasma.

Conclusions

MiR-181d has potential as a biomarker for meningiomas and is associated with the tumor progression of meningiomas.

Toll-like receptors and toll-like receptor-targeted immunotherapy against glioma

Glioma represents a fast proliferating and highly invasive brain tumor which is resistant to current therapies and invariably recurs. Despite some advancements in anti-glioma therapies, patients’ prognosis remains poor. Toll-like receptors (TLRs) act as the first line of defense in the immune system being the detectors of those associated with bacteria, viruses, and danger signals. In the glioma microenvironment, TLRs are expressed on both immune and tumor cells, playing dual roles eliciting antitumoral (innate and adaptive immunity) and protumoral (cell proliferation, migration, invasion, and glioma stem cell maintenance) responses. Up to date, several TLR-targeting therapies have been developed aiming at glioma bulk and stem cells, infiltrating immune cells, the immune checkpoint axis, among others. While some TLR agonists exhibited survival benefit in clinical trials, it attracts more attention when they are involved in combinatorial treatment with radiation, chemotherapy, immune vaccination, and immune checkpoint inhibition in glioma treatment. TLR agonists can be used as immune modulators to enhance the efficacy of other treatment, to avoid dose accumulation, and what brings more interests is that they can potentiate immune checkpoint delayed resistance to PD-1/PD-L1 blockade by upregulating PD-1/PD-L1 overexpression, thus unleash powerful antitumor responses when combined with immune checkpoint inhibitors. Herein, we focus on recent developments and clinical trials exploring TLR-based treatment to provide a picture of the relationship between TLR and glioma and their implications for immunotherapy.

MicroRNAs in Medullary Thyroid Carcinoma: A State of the Art Review of the Regulatory Mechanisms and Future Perspectives

Medullary thyroid carcinoma (MTC) is a rare malignant neoplasia with a variable clinical course, with complete remission often difficult to achieve. Genetic alterations lead to fundamental changes not only in hereditary MTC but also in the sporadic form, with close correlations between mutational status and prognosis. In recent years, microRNAs (miRNAs) have become highly relevant as crucial players in MTC etiology. Current research has focused on their roles in disease carcinogenesis and development, but recent studies have expounded their potential as biomarkers and response predictors to novel biological drugs for advanced MTC. One such element which requires greater investigation is their mechanism of action and the molecular pathways involved in the regulation of gene expression. A more thorough understanding of these mechanisms will help realize the promising potential of miRNAs for MTC therapy and management.

Integrated miRNA-Seq and mRNA-Seq Study to Identify miRNAs Associated With Alzheimer's Disease Using Post-mortem Brain Tissue Samples

Alzheimer's disease (AD), the leading form of dementia, is associated with abnormal tau and β-amyloid accumulation in the brain. We conducted a miRNA-seq study to identify miRNAs associated with AD in the post-mortem brain from the inferior frontal gyrus (IFG, n = 69) and superior temporal gyrus (STG, n = 81). Four and 64 miRNAs were differentially expressed (adjusted p-value < 0.05) in AD compared to cognitively normal controls in the IFG and STG, respectively. We observed down-regulation of several miRNAs that have previously been implicated in AD, including hsa-miR-212-5p and hsa-miR-132-5p, in AD samples across both brain regions, and up-regulation of hsa-miR-146a-5p, hsa-miR-501-3p, hsa-miR-34a-5p, and hsa-miR-454-3p in the STG. The differentially expressed miRNAs were previously implicated in the formation of amyloid-β plaques, the dysregulation of tau, and inflammation. We have also observed differential expressions for dozens of other miRNAs in the STG, including hsa-miR-4446-3p, that have not been described previously. Putative targets of these miRNAs (adjusted p-value < 0.1) were found to be involved in Wnt signaling pathway, MAPK family signaling cascades, sphingosine 1-phosphate (S1P) pathway, adaptive immune system, innate immune system, and neurogenesis. Our results support the finding of dysregulated miRNAs previously implicated in AD and propose additional miRNAs that appear to be dysregulated in AD for experimental follow-up.

microRNA-Based Biomarkers in Alzheimer's Disease (AD)

Alzheimer's disease (AD) is a multifactorial, age-related neurological disease characterized by complex pathophysiological dynamics taking place at multiple biological levels, including molecular, genetic, epigenetic, cellular and large-scale brain networks. These alterations account for multiple pathophysiological mechanisms such as brain protein accumulation, neuroinflammatory/neuro-immune processes, synaptic dysfunction, and neurodegeneration that eventually lead to cognitive and behavioral decline. Alterations in microRNA (miRNA) signaling have been implicated in the epigenetics and molecular genetics of all neurobiological processes associated with AD pathophysiology. These changes encompass altered miRNA abundance, speciation and complexity in anatomical regions of the CNS targeted by the disease, including modified miRNA expression patterns in brain tissues, the systemic circulation, the extracellular fluid (ECF) and the cerebrospinal fluid (CSF). miRNAs have been investigated as candidate biomarkers for AD diagnosis, disease prediction, prognosis and therapeutic purposes because of their involvement in multiple brain signaling pathways in both health and disease. In this review we will: (i) highlight the significantly heterogeneous nature of miRNA expression and complexity in AD tissues and biofluids; (ii) address how information may be extracted from these data to be used as a diagnostic, prognostic and/or screening tools across the entire continuum of AD, from the preclinical stage, through the prodromal, i.e., mild cognitive impairment (MCI) phase all the way to clinically overt dementia; and (iii) consider how specific miRNA expression patterns could be categorized using miRNA reporters that span AD pathophysiological initiation and disease progression.

Role of tissue and circulating microRNAs and DNA as biomarkers in medullary thyroid cancer

Medullary thyroid carcinoma (MTC) is a rare neuroendocrine tumor comprising hereditary or sporadic form with frequent mutations in the rearranged during transfection (RET) or RAS genes. Diagnosis is based on the presence of thyroid tumor mass with altered levels of calcitonin (Ctn) and carcinoembryonal antigen (CEA) in the serum and/or in the cytological smears from fine needle aspiration biopsies. Treatment consists of total thyroidectomy, followed by tyrosine kinase inhibitors (TKi) in case of disease persistence. During TKi treatment, Ctn and CEA levels can fluctuate regardless of tumor volume, metastasis or response to therapy. Research for more reliable non-invasive biomarkers in MTC is still underway. In this context, circulating nucleic acids, namely circulating microRNAs (miRNAs) and cell free DNA (cfDNA), have been evaluated by different research groups. Aiming to shed light on whether miRNAs and cfDNA are suitable as MTC biomarkers we searched three different databases, PubMed, Scopus, WOS and reviewed the literature. We classified 83 publications fulfilling our search criteria and summarized the results. We report data on miRNAs and cfDNA that can be evaluated for validation in independent studies and clinical application.

TLR-4 Signaling vs. Immune Checkpoints, miRNAs Molecules, Cancer Stem Cells, and Wingless-Signaling Interplay in Glioblastoma Multiforme-Future Perspectives

Toll-like-receptor (TLR) family members were detected in the central nervous system (CNS). TLR occurrence was noticed and widely described in glioblastomamultiforme (GBM) cells. After ligand attachment, TLR-4 reorients domains and dimerizes, activates an intracellular cascade, and promotes further cytoplasmatic signaling. There is evidence pointing at a strong relation between TLR-4 signaling and micro ribonucleic acid (miRNA) expression. The TLR-4/miRNA interplay changes typical signaling and encourages them to be a target for modern immunotherapy. TLR-4 agonists initiate signaling and promote programmed death ligand-1 (PD-1L) expression. Most of those molecules are intensively expressed in the GBM microenvironment, resulting in the autocrine induction of regional immunosuppression. Another potential target for immunotreatment is connected with limited TLR-4 signaling that promotes Wnt/DKK-3/claudine-5 signaling, resulting in a limitation of GBM invasiveness. Interestingly, TLR-4 expression results in bordering proliferative trends in cancer stem cells (CSC) and GBM. All of these potential targets could bring new hope for patients suffering from this incurable disease. Clinical trials concerning TLR-4 signaling inhibition/promotion in many cancers are recruiting patients. There is still a lot to do in the field of GBM immunotherapy.

Differentiation Induction and Proliferation Inhibition by A Cell-Free Approach for Delivery of Exogenous miRNAs to Neuroblastoma Cells Using Mesenchymal Stem Cells

Objective

Neuroblastoma (NB) is one of the frequently observed malignant solid tumors of childhood and infancy, accounting for 15% of pediatric cancer deaths. Recently, the approach of differentiation therapy has shown considerable promise in effective treatment of NB patients. MiR-124 belongs to the nervous system-specific miRNAs that is increased during neuronal differentiation and may be one of the potential therapeutic targets for the treatment of NB. However, despite its well-established therapeutic potential, its efficient delivery to the targeted tumor cells is a challenging task. Mesenchymal stem cells (MSCs) are multipotent adult progenitor cells that have antitumor properties, and they can migrate to cancer cells and tumors. This study aimed to assess whether human adipose tissue-derived MSCs (hAD- MSCs) have the potential to deliver exogenous miRNAs to NB cells to induce differentiation and decrease proliferation of cancer cells.

Materials and Methods

In this experimental study, hAD-MSCs were isolated, cultured, and differentiated. The M17 human NB cell line were also cultured. A specific type of miRNAs, i.e., miR-124 was successfully delivered to M17 NB cells with the aid of hAD-MSCs using the direct or indirect (exosome-based) contacts.

Results

It was shown that indirect delivery of miR-124 considerably decreased the proliferation of NB cells and induced their differentiation.

Conclusion

The results suggest the use of delivered exogenous miRNAs by the derived exosomes from hAD-MSCs as a novel cell-free stem cell-based therapy for NB cancer.

Recent Trends of microRNA Significance in Pediatric Population Glioblastoma and Current Knowledge of Micro RNA Function in Glioblastoma Multiforme

Central nervous system tumors are a significant problem for modern medicine because of their location. The explanation of the importance of microRNA (miRNA) in the development of cancerous changes plays an important role in this respect. The first papers describing the presence of miRNA were published in the 1990s. The role of miRNA has been pointed out in many medical conditions such as kidney disease, diabetes, neurodegenerative disorder, arthritis and cancer. There are several miRNAs responsible for invasiveness, apoptosis, resistance to treatment, angiogenesis, proliferation and immunology, and many others. The research conducted in recent years analyzing this group of tumors has shown the important role of miRNA in the course of gliomagenesis. These particles seem to participate in many stages of the development of cancer processes, such as proliferation, angiogenesis, regulation of apoptosis or cell resistance to cytostatics.

MiR-30c-5p mediates inflammatory responses and promotes microglia survival by targeting eIF2α during Cryptococcus neoformans infection

Cryptococcosis is a disease predominantly caused by Cryptococcus neoformans in China and C. neoformans is the main form that causes cryptococcal meningitis. In this study, we examined the influence of MiR-30c-5p during Cryptococcus neoformans infection. microRNAs were extracted from Cerebrospinal fluid and sera of patients. To identify pathogenic microRNAs, RNASeq were performed. The results were confirmed with quantitative real-time PCR (qRT-PCR), transient transfection of siRNAs or microRNA mimics into cultured BV2 cell, flow cytometry, immunoblotting, luciferase assay and immunohistochemistry. In this study we found that miR-30c expression was downregulated and that inflammation, apoptosis, and autophagy were activated. The overexpression of miR-30c-5p significantly inhibited inflammation and autophagic activity and decreased apoptosis, and treatment with sieIF2α resulted in a significant decrease in inflammation, apoptosis. In addition, clinical samples of cerebrospinal fluid and serum of patients with cryptococcal meningitis who have undergone standard antifungal treatment showed that the expression of miR-30c-5p was increased while that of eIF2α was decreased, which was in accordance with the in vitro experiments. These studies demonstrated that miRNA-30c-5p can inhibit inflammatory, apoptotic, and autophagic activity through the eIF2α/ATF4 pathway, and it is thus a potential target for the diagnosis, treatment, and detection of cryptococcal meningitis.

Drugs used to treat bipolar disorder act via microRNAs to regulate expression of genes involved in neurite outgrowth

BACKGROUND

The drugs commonly used to treat bipolar disorder have limited efficacy and drug discovery is hampered by the paucity of knowledge of the pathophysiology of this disease. This study aims to explore the role of microRNAs in bipolar disorder and understand the molecular mechanisms of action of commonly used bipolar disorder drugs.

METHODS

The transcriptional effects of bipolar disorder drug combination (lithium, valproate, lamotrigine and quetiapine) in cultured human neuronal cells were studied using next generation sequencing. Differential expression of genes (n=20) and microRNAs (n=6) was assessed and the differentially expressed microRNAs were confirmed with TaqMan MicroRNA Assays. The expression of the differentially expressed microRNAs were inhibited to determine bipolar disorder drug effects on their target genes (n=8). Independent samples t-test was used for normally distributed data and Kruskal-Wallis/Mann-Whitney U test was used for data not distributed normally. Significance levels were set at p<0.05.

RESULTS

We found that bipolar disorder drugs tended to increase the expression of miR-128 and miR-378 (p<0.05). Putative target genes of these microRNAs targeted pathways including those identified as "neuron projection development" and "axonogenesis". Many of the target genes are inhibitors of neurite outgrowth and neurogenesis and were downregulated following bipolar disorder drug combination treatment (all p<0.05). The bipolar disorder drug combination tended to decrease the expression of the target genes (NOVA1, GRIN3A, and VIM), however this effect could be reversed by the application of microRNA inhibitors.

CONCLUSIONS

We conclude that at a transcriptional level, bipolar disorder drugs affect several genes in concert that would increase neurite outgrowth and neurogenesis and hence neural plasticity, and that this effect is mediated (at least in part) by modulation of the expression of these two key microRNAs.

Micro RNA Molecules as Modulators of Treatment Resistance, Immune Checkpoints Controllers and Sensitive Biomarkers in Glioblastoma Multiforme

Based on genome sequencing, it is estimated that over 90% of genes stored in human genetic material are transcribed, but only 3% of them contain the information needed for the production of body proteins. This group also includes micro RNAs representing about 1%–3% of the human genome. Recent studies confirmed the hypothesis that targeting molecules called Immune Checkpoint (IC) open new opportunities to take control over glioblastoma multiforme (GBM). Detection of markers that indicate the presence of the cancer occupies a very important place in modern oncology. This function can be performed by both the cancer cells themselves as well as their components and other substances detected in the patients’ bodies. Efforts have been made for many years to find a suitable marker useful in the diagnosis and monitoring of gliomas, including glioblastoma.

Identifying lncRNA-miRNA-mRNA networks to investigate Alzheimer's disease pathogenesis and therapy strategy

Alzheimer’s disease (AD), the most common cause of dementia, leads to neuronal damage and deterioration of cognitive functions in aging brains. There is evidence suggesting the participation of noncoding RNAs in AD-associated pathophysiology. A potential linkage between AD and lncRNA-associated competing endogenous RNA (ceRNA) networks has been revealed. Nevertheless, there are still no genome-wide studies which have identified the lncRNA-associated ceRNA pairs involved in AD. For this reason, deep RNA-sequencing was performed to systematically investigate lncRNA-associated ceRNA mechanisms in AD model mice (APP/PS1) brains. Our results identified 487, 89, and 3,025 significantly dysregulated lncRNAs, miRNAs, and mRNAs, respectively, and the most comprehensive lncRNA-associated ceRNA networks to date are constructed in the APP/PS1 brain. GO analysis revealed the involvement of the identified networks in regulating AD development from distinct origins, such as synapses and dendrites. Following rigorous selection, the lncRNA-associated ceRNA networks in this AD mouse model were found to be mainly involved in synaptic plasticity as well as memory (Akap5) and regulation of amyloid-β (Aβ)-induced neuroinflammation (Klf4). This study presents the first systematic dissection of lncRNA-associated ceRNA profiles in the APP/PS1 mouse brain. The identified lncRNA-associated ceRNA networks could provide insights that facilitate AD diagnosis and future treatment strategies.

Extracellular microRNAs in blood differentiate between ischaemic and haemorrhagic stroke subtypes

Rapid identification of patients suffering from cerebral ischaemia, while excluding intracerebral haemorrhage, can assist with patient triage and expand patient access to chemical and mechanical revascularization. We sought to identify blood-based, extracellular microRNAs 15 (ex-miRNAs) derived from extracellular vesicles associated with major stroke subtypes using clinical samples from subjects with spontaneous intraparenchymal haemorrhage (IPH), aneurysmal subarachnoid haemorrhage (SAH) and ischaemic stroke due to cerebral vessel occlusion. We collected blood from patients presenting with IPH (n = 19), SAH (n = 17) and ischaemic stroke (n = 21). We isolated extracellular vesicles from plasma, extracted RNA cargo, 20 sequenced the small RNAs and performed bioinformatic analyses to identify ex-miRNA biomarkers predictive of the stroke subtypes. Sixty-seven miRNAs were significantly variant across the stroke subtypes. A subset of exmiRNAs differed between haemorrhagic and ischaemic strokes, and LASSO analysis could distinguish SAH from the other subtypes with an accuracy of 0.972 ± 0.002. Further analyses predicted 25 miRNA classifiers that stratify IPH from ischaemic stroke with an accuracy of 0.811 ± 0.004 and distinguish haemorrhagic from ischaemic stroke with an accuracy of 0.813 ± 0.003. Blood-based, ex-miRNAs have predictive value, and could be capable of distinguishing between major stroke subtypes with refinement and validation. Such a biomarker could one day aid in the triage of patients to expand the pool eligible for effective treatment.

Differential expression of microRNAs in Alzheimer's disease brain, blood, and cerebrospinal fluid

INTRODUCTION

Several microRNAs (miRNAs) have been implicated in Alzheimer's disease pathogenesis, but the evidence from individual case-control studies remains inconclusive.

METHODS

A systematic literature review was performed, followed by standardized multistage data extraction, quality control, and meta-analyses on eligible data for brain, blood, and cerebrospinal fluid specimens. Results were compared with miRNAs reported in the abstracts of eligible studies or recent qualitative reviews to assess novelty.

RESULTS

Data from 147 independent data sets across 107 publications were quantitatively assessed in 461 meta-analyses. Twenty-five, five, and 32 miRNAs showed studywide significant differential expression (α < 1·08 × 10^-4) in brain, cerebrospinal fluid, and blood-derived specimens, respectively, with 5 miRNAs showing differential expression in both brain and blood. Of these 57 miRNAs, 13 had not been reported in the abstracts of previous original or review articles.

DISCUSSION

Our systematic assessment of differential miRNA expression is the first of its kind in Alzheimer's disease and highlights several miRNAs of potential relevance.

An investigation of microRNA-103 and microRNA-107 as potential blood-based biomarkers for disease risk and progression of Alzheimer's disease

BACKGROUND

This study aimed to assess the correlation of circulating microRNA-103 (miR-103) and microRNA-107 (miR-107) with disease risk and cognitive impairment of Alzheimer's disease (AD).

METHODS

Plasma samples from 120 AD patients, 120 Parkinson's disease (PD) patients (served as disease control), and 120 healthy controls were collected for miR-103 and miR-107 detections using real-time quantitative polymerase chain reaction. Mini-Mental State Examination (MMSE) score was documented and was used to accordingly assess the dementia severity.

RESULTS

miR-103 expression was decreased in AD patients compared with PD patients and healthy controls, and receiver operating characteristic (ROC) curve analyses illustrated that it was able to differentiate AD patients from PD patients and healthy controls. Additionally, miR-103 positively correlated with MMSE score and negatively correlated with dementia severity in AD patients. miR-107 expression was lower in AD patients compared with healthy controls but similar between AD patients and PD patients, and ROC curve analyses revealed that it was able to differentiate AD patients from healthy controls but not AD patients from PD patients. miR-107 was positively correlated with MMSE score and negatively correlated with dementia severity in AD patients, while the correlation coefficient of miR-107 with MMSE score was lower than that of miR-103 with MMSE score. Besides, miR-103 was positively correlated with miR-107 in AD patients, PD patients, and healthy controls.

CONCLUSION

miR-103 may be a better choice than miR-107 to serve as a potential biomarker for disease risk and disease progression of AD.

Exosomal microRNA profiles from serum and cerebrospinal fluid in neurosyphilis

OBJECTIVE

Changes in microRNAs (miRNAs) in the cerebrospinal fluid (CSF) are associated with different neurological diseases. Since alternations of miRNAs in neurosyphilis are insufficiently investigated, we analysed miRNAs in the CSF of patients suffering from neurosyphilis.

METHODS

Exosomes were isolated from serum and CSF. Levels of 44 miRNAs were determined using quantitative real-time PCR-based miRNA array.

RESULTS

In patients with neurosyphilis (NSP), miR-590-5p, miR-570-3p and miR-570-5p were upregulated in the CSF and serum, when compared with patients with syphilis without neurosyphilis (SP). miR-590-5p and miR-570-3p were significantly upregulated (p<0.001). The expression of miR-21-5p was upregulated only in the CSF of NSP. Significant downregulation was observed for miR-93-3p in the CSF and serum of NSP. No statistical difference was found in the expression of miR-7-5p, miR-1307-5p, miR-203a-3p, miR-16, miR-23b-3p and miR-27b-5p in the CSF and serum of NSP and SP.

CONCLUSION

For the first time, regulation profiles in miRNA in the CSF and serum were analysed in NSP. We found significant differences in upregulation and downregulation. Therefore, miRNAs may be potential biomarkers for the presence of neurosyphilis.

Serum miR-30c-5p is a potential biomarker for multiple system atrophy

Multiple system atrophy (MSA) is a neurodegenerative disease that belongs to the α synucleinopathies. Clinically, there is an overlap between MSA and Parkinson's disease (PD), especially at the early disease stage. However, these two pathologies differ in terms of disease progression. Currently, no biomarker exists to differentiate MSA from PD. MicroRNAs are non-coding RNAs implicated in gene expression regulation. MiRNAs modulate cellular activity and they control a range of physiological and pathological functions. miRNAs are found in biofluids, such as blood, serum, plasma, saliva, and cerebrospinal fluid. Many groups, including ours, found that circulating miRNAs are differently expressed in blood, plasma, serum and cerebrospinal fluid of PD and MSA patients. In the present study, our primary aim was to determine if serum mir-30-5p and mir-148b-5p can be used as biomarkers for early diagnosis of PD and/or MSA. Our secondary goal was to determine if serum levels of those miRNAs can be correlated with the patients' clinical profile. Using quantitative PCR (qPCR), we evaluated expression levels of miR-30c-5p and miR148b-5p in serum samples from PD (n = 56), MSA (n = 49), and healthy control (n = 50) subjects. We have found that miR-30c-5p is significantly upregulated in MSA if compared with PD and healthy control subjects. Moreover, serum miR-30c-5p levels correlate with disease duration in both MSA and PD. No significant difference was found in miR-148b-5p among MSA, PD and healthy control subjects. Our results suggest a possible role of serum miR-30-5p as a biomarker for diagnosis and progression of MSA.

Competing Endogenous RNA Regulations in Neurodegenerative Disorders: Current Challenges and Emerging Insights

The past decade has witnessed exciting breakthroughs that have contributed to the richness and complexity of a burgeoning modern RNA world, and one particular breakthrough-the competing endogenous RNA (ceRNA) hypothesis-has been described as the "Rosetta Stone" for decoding the RNA language used in regulating RNA crosstalk and modulating biological functions. The proposed far-reaching mechanism unites diverse RNA species and provides new insights into previously unrecognized RNA-RNA interactions and RNA regulatory networks that perhaps determine gene expression in an organized, hierarchical manner. The recently uncovered ceRNA regulatory loops and networks have emphasized the power of ceRNA regulation in a wide range of developmental stages and pathological contexts, such as in tumorigenesis and neurodegenerative disorders. Although the ceRNA hypothesis drastically enhanced our understanding of RNA biology, shortly after the hypothesis was proposed, disputes arose in relation mainly to minor discrepancies in the reported effects of ceRNA regulation under physiological conditions, and this resulted in ceRNA regulation becoming an extensively studied and fast-growing research field. Here, we focus on the evidence supporting ceRNA regulation in neurodegenerative disorders and address three critical points related to the ceRNA regulatory mechanism: the microRNA (miRNA) and ceRNA hierarchies in cross-regulations; the balance between destabilization and stable binding in ceRNA-miRNA interactions; and the true extent to which ceRNA regulatory mechanisms are involved in both health and disease, and the experimental shortcomings in current ceRNA studies.

MicroRNA-26b Regulates the Microglial Inflammatory Response in Hypoxia/Ischemia and Affects the Development of Vascular Cognitive Impairment

Background: Microglia play an important role in the central nervous system as immune cells and are often activated by post-ischemic injury. MicroRNAs are small endogenous RNAs affecting many complex cellular biological functions that are involved in neurodegenerative and cerebrovascular diseases. Previous studies have shown that microRNA-26b (miR-26b) is downregulated in BV-2 cells exposed to oxygen-glucose deprivation (OGD).

Objective: This study aimed to investigate how miR-26b regulates microglial activation and its neurotoxicity as well as the effect of miR-26b on vascular cognitive impairment (VCI).

Methods: Here, we used PCR to detect the mRNA expression of miR-26b and cytokines, western blot for the protein expression of cytokines, and the live/dead assay for neuronal apoptosis. In addition, we employed a luciferase assay to identify the possible target genes of miR-26b. Furthermore, we studied the effects of cerebral ischemia by bilateral common carotid artery occlusion (BCCAO) in rats. We used staining to identify neurons and microglia, and we tested cognitive function by the T-maze test.

Results: Our results showed that OGD activated microglia and increased the expression of interleukin (IL)-6 and other cytokines. Similarly, BCCAO activated microglia and increased the expression of IL-6 in the hippocampal CA1 area. We further found that miR-26b decreased the number of activated microglia and targeted IL-6. Moreover, miR-26b expression attenuated microglial activation, inflammation, neurotoxicity and VCI.

Conclusion: Our results suggested that miR-26b is involved in microglial activation and neurotoxicity in hypoxia/ischemia via IL-6. Therefore, increasing miR-26b expression may improve cognitive function.

Exosomes confer pro-survival signals to alter the phenotype of prostate cells in their surrounding environment

Prostate cancer (PCa) is the most frequently diagnosed cancer in men. Current research on tumour-related extracellular vesicles (EVs) suggests that exosomes play a significant role in paracrine signaling pathways, thus potentially influencing cancer progression via multiple mechanisms. In fact, during the last decade numerous studies have revealed the role of EVs in the progression of various pathological conditions including cancer. Moreover, differences in the proteomic, lipidomic, and cholesterol content of exosomes derived from PCa cell lines versus benign prostate cell lines confirm that exosomes could be excellent biomarker candidates. As such, as part of an extensive proteomic analysis using LCMS we previously described a potential role of exosomes as biomarkers for PCa. Current evidence suggests that uptake of EV's into the local tumour microenvironment encouraging us to further examine the role of these vesicles in distinct mechanisms involved in the progression of PCa and castration resistant PCa. For the purpose of this study, we hypothesized that exosomes play a pivotal role in cell-cell communication in the local tumour microenvironment, conferring activation of numerous survival mechanisms during PCa progression and development of therapeutic resistance. Our in vitro results demonstrate that PCa derived exosomes significantly reduce apoptosis, increase cancer cell proliferation and induce cell migration in LNCaP and RWPE-1 cells. In conjunction with our in vitro findings, we have also demonstrated that exosomes increased tumor volume and serum PSA levels in vivo when xenograft bearing mice were administered DU145 cell derived exosomes intravenously. This research suggests that, regardless of androgen receptor phenotype, exosomes derived from PCa cells significantly enhance multiple mechanisms that contribute to PCa progression.

A 4-miRNA signature predicts the therapeutic outcome of glioblastoma

Multimodal therapy of glioblastoma (GBM) reveals inter-individual variability in terms of treatment outcome. Here, we examined whether a miRNA signature can be defined for the a priori identification of patients with particularly poor prognosis.

FFPE sections from 36 GBM patients along with overall survival follow-up were collected retrospectively and subjected to miRNA signature identification from microarray data. A risk score based on the expression of the signature miRNAs and cox-proportional hazard coefficients was calculated for each patient followed by validation in a matched GBM subset of TCGA. Genes potentially regulated by the signature miRNAs were identified by a correlation approach followed by pathway analysis.

A prognostic 4-miRNA signature, independent of MGMT promoter methylation, age, and sex, was identified and a risk score was assigned to each patient that allowed defining two groups significantly differing in prognosis (p-value: 0.0001, median survival: 10.6 months and 15.1 months, hazard ratio = 3.8). The signature was technically validated by qRT-PCR and independently validated in an age- and sex-matched subset of standard-of-care treated patients of the TCGA GBM cohort (n=58). Pathway analysis suggested tumorigenesis-associated processes such as immune response, extracellular matrix organization, axon guidance, signalling by NGF, GPCR and Wnt. Here, we describe the identification and independent validation of a 4-miRNA signature that allows stratification of GBM patients into different prognostic groups in combination with one defined threshold and set of coefficients that could be utilized as diagnostic tool to identify GBM patients for improved and/or alternative treatment approaches.

Circulating MicroRNAs in Elderly Type 2 Diabetic Patients

The circulating microRNAs (miRNAs) associated with type 2 diabetes (T2D) in elderly patients are still being defined. To identify novel miRNA biomarker candidates for monitoring responses to sitagliptin in such patients, we prospectively studied 40 T2D patients (age > 65) with HbA1c levels of 7.5-9.0% on metformin. After collection of baseline blood samples (t₀), the dipeptidyl peptidase-IV (DPP-IV) inhibitor (DPP-IVi) sitagliptin was added to the metformin regimen, and patients were followed for 15 months. Patients with HbA1c < 7.5% or HbA1c reduction > 0.5% after 3 and 15 months of therapy were classified as "responders" (group R, n = 34); all others were classified as "nonresponders" (group NR, n = 6). Circulating miRNA profiling was performed on plasma collected in each group before and after 15 months of therapy (t₀ and t₁₅). Intra- and intergroup comparison of miRNA profiles pinpointed three miRNAs that correlated with responses to sitagliptin: miR-378, which is a candidate biomarker of resistance to this DPP-IVi, and miR-126-3p and miR-223, which are associated with positive responses to the drug. The translational implications are as immediate as evident, with the possibility to develop noninvasive diagnostic tools to predict drug response and development of chronic complications.

Loss of miR-107, miR-181c and miR-29a-3p Promote Activation of Notch2 Signaling in Pediatric High-Grade Gliomas (pHGGs)

The mechanisms by which microRNAs control pediatric high-grade gliomas (pHGGs) have yet to be fully elucidated. Our studies of patient-derived pHGG tissues and of the pHGG cell line KNS42 revealed down-regulation in these tumors of three microRNAs, specifically miR-107, miR-181c, and miR-29a-3p. This down-regulation increases the proliferation of KNS42 cells by de-repressing expression of the Notch2 receptor (Notch2), a validated target of miR-107 and miR-181c and a putative target of miR-29a-3p. Inhibition (either pharmacologic or genetic) of Notch2 or re-expression of the implicated microRNAs (all three combined but also individually) significantly reduced KNS42 cell proliferation. These findings suggest that Notch2 pathway activation plays a critical role in pHGGs growth and reveal a direct epigenetic mechanism that controls Notch2 expression, which could potentially be targeted by novel forms of therapy for these childhood tumors characterized by high-morbidity and high-mortality.

Suppression of microRNA-9-5p rescues learning and memory in chronic cerebral hypoperfusion rats model

Chronic cerebral hypoperfusion has been associated with cognitive impairment in dementias, such as Alzheimer's disease (AD) and vascular disease (VaD), the two most common neurodegenerative diseases in aged people. However, the effective therapeutic approaches for both AD and VaD are still missing. MicroRNAs (miRNAs) are small non-coding RNAs that play important roles in the epigenetic regulation in many neurological disorders; the critical roles of miRNAderegulation had been implicated in both AD and VaD. In the current study, we reported that miR-9-5p is elevated in the serum and cerebrospinalfluid of patientswith VaD. The miR-9-5p wasalso increased in both the hippocampus and cortex of rats with 2-vessel occlusionsurgery. Furthermore, application ofmiR-9-5p antagomirs attenuated the memory impairments in rats with 2-vessel occlusion surgery both in the Morris water maze and inhibitory avoidance step-down tasks. Furthermore, miR-9-5p antagomirs reducedthe inhibition oflong-term potentiation and loss of dendritic spines in chronic cerebral hypoperfusionrats. Additionally, the cholinergic neuronal function was rescued by miR-9-5p antagomirs, as well as the neuronal loss and the oxidative stress. We concluded that miR-9-5p inhibition may be a potential therapeutic target for the memory impairments caused by chronic cerebral hypoperfusion.

Selectivity enhancements in gel-based DNA-nanoparticle assays by membrane-induced isotachophoresis: thermodynamics versus kinetics

Selectivity against mutant nontargets with a few mismatches remains challenging in nucleic acid sensing. Sensitivity enhancement by analyte concentration does not improve selectivity because it affects targets and nontargets equally. Hydrodynamic or electrical shear enhanced selectivity is often accompanied by substantial losses in target signals, thereby leading to poor limits of detection. We introduce a platform based on depletion isotachophoresis in agarose gel generated by an ion-selective membrane that allows both selectivity and sensitivity enhancement with a two-step assay involving concentration polarization at an ion-selective membrane. By concentrating both the targets and probe-functionalized nanoparticles by ion enrichment at the membrane, the effective thermodynamic dissociation constant is lowered from 40 nM to below 500 pM, and the detection limit is 10 pM as reported previously. A dynamically optimized ion depletion front is then generated from the membrane with a high electrical shear force to selectively and irreversibly dehybridize nontargets. The optimized selectivity against a two-mismatch nontarget (in a 35-base pairing sequence) is shown to be better than the thermodynamic equilibrium selectivity by more than a hundred-fold, such that there is no detectable signal from the two-mismatch nontarget. We offer empirical evidence that irreversible cooperative dehybridization plays an important role in this kinetic selectivity enhancement and that mismatch location controls the optimum selectivity even when there is little change in the corresponding thermodynamic dissociation constant.

[The microRNAs as biomarkers: What prospects?]

MicroRNAs are nucleic acids of about twenty nucleotides that regulate about a third of the genome at the post-transcriptional level. Thanks to their different forms of transport, microRNAs are stable and can be detected in biological fluids such as blood, urine, cerebrospinal fluid, or saliva. In addition, the profile of circulating microRNAs is a specific part of the cells in which it is secreted and is modified according to the physiological or pathological conditions of these cells. MicroRNAs therefore appear as biomarkers of interest for many diseases. However, these applications face several challenges because there are currently considerable differences between the sample processing procedures, assay methods, and especially the result standardization strategies. This literature review aims to take stock of the current use of microRNAs as biomarkers mainly in biological fluids and address the perspectives that emerge from the fact that their vesicular circulating forms could be used to assess the state of the cells and the tissues that produce them.

Aberrant Expression of miR-323a-5p in Patients with Refractory Epilepsy Caused by Focal Cortical Dysplasia

BACKGROUND

Epilepsy remains one of the most common clinical neurological disorders. About a third of patients with epilepsy are refractory to drug treatment, mainly as a result of focal cortical dysplasia (FCD). In this study, we analyzed the aberrant expression of microRNAs (miRNAs) in the cortex and plasma of FCD patients.

METHODS

Cortical samples were collected from nine patients with refractory epilepsy caused by FCD who underwent surgery, and from eight volunteers (control group) undergoing emergency surgery for hypertensive cerebral hemorrhage. miRNA expression in the cortex was detected by microarray analysis and miR-323a-5p expression levels in the cortex were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR). We also collected plasma samples from 30 patients with refractory epilepsy caused by FCD and from 23 healthy controls, and compared differential expression of miR-323a-5p in the plasma using qRT-PCR.

RESULTS

miRNA microarray analysis showed that expression of miR-323a-5p was upregulated in the FCD group compared with the control group, and miR-323a-5p expression levels in the cortex analyzed by qRT-PCR supported those obtained by microarray analysis. Plasma levels of miR-323a-5p were significantly higher in patient plasma compared with the healthy controls, as determined by qRT-PCR. Furthermore, expression of miR-323a-5p was positively correlated with the duration of epilepsy (p = 0.014) and seizure frequency (p = 0.043). The effectiveness of surgery in patients with FCD was significantly poorer in patients with high plasma levels of miR-323a-5p compared with those with low levels.

CONCLUSIONS

The expression of miR-323a-5p was significantly elevated in the cortex and plasma of FCD patients. These results suggest that abnormal expression of miR-323a-5p could be used for improving the current diagnosis of FCD and monitoring treatment responses in patients with FCD.

miRNAs and their role in the correlation between schizophrenia and cancer (Review)

Schizophrenia (SZ) and cancer (Ca) have a broad spectrum of clinical phenotypes and a complex biological background, implicating a large number of genetic and epigenetic factors. SZ is a chronic neurodevelopmental disorder signified by an increase in the expression of apoptotic molecular signals, whereas Ca is conversely characterized by an increase in appropriate molecular signaling that stimulates uncontrolled cell proliferation. The rather low risk of developing Ca in patients suffering from SZ is a hypothesis that is still under debate. Recent evidence has indicated that microRNAs (miRNAs or miRs), a large group of small non-coding oligonoucleotides, may play a significant role in the development of Ca and major psychiatric disorders, such as SZ, bipolar disorder, autism spectrum disorders, suicidality and depression, through their interference with the expression of multiple genes. For instance, the possible role of let-7, miR-98 and miR-183 as biomarkers for Ca and SZ was investigated in our previous research studies. Therefore, further investigations on the expression profiles of these regulatory, small RNA molecules and the molecular pathways through which they exert their control may provide a plausible explanation as to whether there is a correlation between psychiatric disorders and low risk of developing Ca.

Sustained lentiviral-mediated overexpression of microRNA124a in the dentate gyrus exacerbates anxiety- and autism-like behaviors associated with neonatal isolation in rats

Autism spectrum disorders (ASD) are highly disabling psychiatric disorders. Despite a strong genetic etiology, there are no efficient therapeutic interventions that target the core symptoms of ASD. Emerging evidence suggests that dysfunction of microRNA (miR) machinery may contribute to the underlying molecular mechanisms involved in ASD. Here, we report a stress model demonstrating that neonatal isolation-induced long-lasting hippocampal elevation of miR124a was associated with reduced expression of its target BDNF mRNA. In addition, we investigated the impact of lentiviral-mediated overexpression of miR124a into the dentate gyrus (DG) on social interaction, repetitive- and anxiety-like behaviors in the neonatal isolation (Iso) model of autism. Rats isolated from the dams on PND 1 to PND 11 were assessed for their social interaction, marble burying test (MBT) and repetitive self-grooming behaviors as adults following miR124a overexpression. Also, anxiety-like behavior and locomotion were evaluated in the elevated plus maze (EPM) and open-field (OF) tests. Results show that, consistent with previously published reports, Iso rats displayed decreased social interaction contacts but increased repetitive- and anxiety-like behaviors. Interestingly, across both autism- and anxiety-like behavioral assays, miR124a overexpression in the DG significantly exacerbated repetitive behaviors, social impairments and anxiety with no effect on locomotor activity. Our novel findings attribute neonatal isolation-inducible cognitive impairments to induction of miR124a and consequently suppressed BDNF mRNA, opening venues for intercepting these miR124a-mediated damages. They also highlight the importance of studying microRNAs in the context of ASD and identify miR124a as a novel potential therapeutic target for improving mood disorders.

Defining Plasma MicroRNAs Associated With Cognitive Impairment In HIV-Infected Patients

Human Immunodeficiency Virus (HIV)-infected individuals are at increased risk for developing neurocognitive disorders and depression. These conditions collectively affect more than 50% of people living with HIV/AIDS and adversely impact adherence to HIV therapy. Thus, identification of early markers of neurocognitive impairment could lead to interventions that improve psychosocial functioning and slow or reverse disease progression through improved treatment adherence. Evidence has accumulated for the role and function of microRNAs in normal and pathological conditions. We have optimized a protocol to profile microRNAs in body fluids. Using this methodology, we have profiled plasma microRNA expression for 30 age-matched, HIV-infected (HIV(+) ) patients and identified highly sensitive and specific microRNA signatures distinguishing HIV(+) patients with cognitive impairment from those without cognitive impairment. These results justify follow-on studies to determine whether plasma microRNA signatures can be used as a screening or prognostic tool for HIV(+) patients with neurocognitive impairment. J. Cell. Physiol. 231: 829-836, 2016. © 2015 Wiley Periodicals, Inc.

microRNAs That Promote or Inhibit Memory Formation in Drosophila melanogaster

microRNAs (miRNAs) are small noncoding RNAs that regulate gene expression post-transcriptionally. Prior studies have shown that they regulate numerous physiological processes critical for normal development, cellular growth control, and organismal behavior. Here, we systematically surveyed 134 different miRNAs for roles in olfactory learning and memory formation using "sponge" technology to titrate their activity broadly in the Drosophila melanogaster central nervous system. We identified at least five different miRNAs involved in memory formation or retention from this large screen, including miR-9c, miR-31a, miR-305, miR-974, and miR-980. Surprisingly, the titration of some miRNAs increased memory, while the titration of others decreased memory. We performed more detailed experiments on two miRNAs, miR-974 and miR-31a, by mapping their roles to subpopulations of brain neurons and testing the functional involvement in memory of potential mRNA targets through bioinformatics and a RNA interference knockdown approach. This screen offers an important first step toward the comprehensive identification of all miRNAs and their potential targets that serve in gene regulatory networks important for normal learning and memory.

The MiRNA Journey from Theory to Practice as a CNS Biomarker

MicroRNAs (miRNAs), small nucleotide sequences that control gene transcription, have the potential to serve an expanded function as indicators in the diagnosis and progression of neurological disorders. Studies involving debilitating neurological diseases such as, Alzheimer's disease, multiple sclerosis, traumatic brain injuries, Parkinson's disease and CNS tumors, already provide validation for their clinical diagnostic use. These small nucleotide sequences have several features, making them favorable candidates as biomarkers, including function in multiple tissues, stability in bodily fluids, a role in pathogenesis, and the ability to be detected early in the disease course. Cerebrospinal fluid, with its cell-free environment, collection process that minimizes tissue damage, and direct contact with the brain and spinal cord, is a promising source of miRNA in the diagnosis of many neurological disorders. Despite the advantages of miRNA analysis, current analytic technology is not yet affordable as a clinically viable diagnostic tool and requires standardization. The goal of this review is to explore the prospective use of CSF miRNA as a reliable and affordable biomarker for different neurological disorders.

Differential Expression and Significance of Circulating microRNAs in Cerebrospinal Fluid of Acute Encephalitis Patients Infected with Japanese Encephalitis Virus

Changes in circulating microRNAs (miRNAs) in the cerebrospinal fluid (CSF) have been associated with different neurological diseases. Here, we presented results of a pilot study aimed at determining the feasibility of detecting miRNAs in the CSF of Japanese Encephalitis virus (JEV) infected individuals with acute encephalitis syndrome (AES). We demonstrated the circulating miRNA profile in CSF of acute encephalitis patients infected with JEV. Using a quantitative real-time PCR-based miRNA array, we examined the level of 87 miRNAs expressed in human exosomes isolated from CSF. Subsequently, correlation between cytokine level and miRNAs expression in CSF samples was examined. In this study, we identified and validated the upregulated expression of three miRNAs, miR-21-5p, miR-150-5p, and miR-342-3p that were specifically circulated in CSF of acute encephalitis patients infected with JEV. CSF miR-21-5p, miR-150-5p, and miR-342-3p expressions were also elevated in infected mice brain. However, the expression pattern of these miRNAs differed in neuronal cells, microglial cells, and the exosome derived from JEV-infected cell culture supernatant. Interestingly, neuronal cells infected with vaccine strain (SA-14-14) did not lead to any upregulation of these three miRNAs. Further, miR-150-5p expression was found to be negatively correlated(r = -0.5279, p = 0.016) with TNFα level. Pathway analysis of putative target genes of these miRNAs indicated involvement of TGF-β, NGF, axon guidance, and MAPK signaling pathways in JEV/AES patients. This study for the first time represents the circulating miRNA in CSF of AES patients and identified the upregulated miRNAs in JEV-infected patients and offers the basis for future investigation.

miRNAs as Circulating Biomarkers for Alzheimer's Disease and Parkinson's Disease

Detection of biomarkers for neurodegenerative disorders (NDDs) within brain tissues of Alzheimer's disease (AD) and Parkinson's disease (PD) patients has always been hampered by our inability to access and biopsy tissue of key brain regions implicated in disease occurrence and progression. Currently, diagnosis of NDDs is principally based on clinical observations of symptoms that present at later stages of disease progression, followed by neuroimaging and, possibly, CSF evaluation. One way to potentially detect and diagnose NDDs at a far earlier stage is to screen for abnormal levels of specific disease markers within the peripheral circulation of patients with NDDs. Increasing evidence suggests that there is dysregulation of microRNAs (miRNAs) in NDDs. Peripheral blood mononuclear cells, as well as biofluids, such as plasma, serum, urine and cerebrospinal fluid, contain miRNAs that can be identified and quantified. Circulating miRNAs within blood and other biofluids may thus be characterized and used as non-invasive, diagnostic biomarkers that facilitate the early detection of disease and potentially the continual monitoring of disease progression for NDDs such as AD and PD. Plainly, such a screen is only possible with a clear understanding of which miRNAs change with disease, and when these changes occur during the progression of AD and PD. Such information is becoming increasingly available and, in the near future, may not only support disease diagnosis, but provide the opportunity to evaluate therapeutic interventions earlier in the disease process.

Exosomes: From Functions in Host-Pathogen Interactions and Immunity to Diagnostic and Therapeutic Opportunities

Since their first description in the 1980s, exosomes, small endosomal-derived extracellular vesicles, have been involved in innate and adaptive immunity through modulating immune responses and mediating antigen presentation. Increasing evidence has reported the role of exosomes in host-pathogen interactions and particularly in the activation of antimicrobial immune responses. The growing interest concerning exosomes in infectious diseases, their accessibility in various body fluids, and their capacity to convey a rich content (e.g., proteins, lipids, and nucleic acids) to distant recipient cells led the scientific community to consider the use of exosomes as potential new diagnostic and therapeutic tools. In this review, we summarize current understandings of exosome biogenesis and their composition and highlight the function of exosomes as immunomodulators in pathological states such as in infectious disorders. The potential of using exosomes as diagnostic and therapeutic tools is also discussed.