A guide to microRNA‐mediated gene silencing

miRNA, phytometabolites and disease: Connecting the dots

miRNAs are tiny noncoding ribonucleotides that function as critical regulators of gene-expression in eukaryotes. A single miRNA may be involved in the regulation of several target mRNAs forming complex cellular networks to regulate diverse aspects of development in an organism. The deregulation of miRNAs has been associated with several human diseases. Therefore, miRNA-based therapeutics is gaining interest in the pharmaceutical industry as the next-generation drugs for the cure of many diseases. Medicinal plants have also been used for the treatment of several human diseases and their curative potential is attributed to their reserve in bioactive metabolites. A role for miRNAs as regulators of the phytometabolic pathways in plants has emerged in the recent past. Experimental studies have also indicated the potential of plant encoded secondary phytometabolites to act as cross-regulators of mammalian miRNAs and transcripts to regulate human diseases (like cancer). The evidence for this cross-kingdom gene regulation through miRNA has gathered considerable enthusiasm in the scientific field, even though there are on-going debates regarding the reproducibility and the effectiveness of these findings. In this review, we provide information to connect the medicinal and gene regulatory properties of secondary phytometabolites, their regulation by miRNAs in plants and their effects on human miRNAs for regulating downstream metabolic or pathological processes. While further extensive research initiatives and good clinical evidence are required to prove or disapprove these findings, understanding of these regulations will have important implications in the potential use of synthetic or artificial miRNAs as effective alternatives for providing health benefits.

MicroRNAs in meningiomas: Potential biomarkers and therapeutic targets

Meningiomas, characterized primarily as benign intracranial or spinal tumors, present distinctive challenges due to their variable clinical behavior, with certain cases exhibiting aggressive features linked to elevated morbidity and mortality. Despite their prevalence, the underlying molecular mechanisms governing the initiation and progression of meningiomas remain insufficiently understood. MicroRNAs (miRNAs), small endogenous non-coding RNAs orchestrating post-transcriptional gene expression, have garnered substantial attention in this context. They emerge as pivotal biomarkers and potential therapeutic targets, offering innovative avenues for managing meningiomas. Recent research delves into the intricate mechanisms by which miRNAs contribute to meningioma pathogenesis, unraveling the molecular complexities of this enigmatic tumor. Meningiomas, originating from arachnoid meningothelial cells and known for their gradual growth, constitute a significant portion of intracranial tumors. The clinical challenge lies in comprehending their progression, particularly factors associated with brain invasion and heightened recurrence rates, which remain elusive. This comprehensive review underscores the pivotal role of miRNAs, accentuating their potential to advance our comprehension of meningioma biology. Furthermore, it suggests promising directions for developing diagnostic biomarkers and therapeutic interventions, holding the promise of markedly improved patient outcomes in the face of this intricate and variable disease.

miR-21, miR-29a, and miR-106b: serum and tissue biomarkers with diagnostic potential in metastatic testicular cancer

The imperative need for sensitive and precise tools is underscored in cancer diagnostics, with biomarkers playing a pivotal role in facilitating early detection and tumor diagnosis. Despite their classical pathological classification, testicular tumors lack valuable markers, emphasizing the necessity to identify and apply serum tumor markers in clinical management. Unfortunately, existing biomarkers exhibit limited sensitivities and specificities. Recent years have witnessed the discovery of novel RNA molecules, presenting a potential breakthrough as diagnostic tools and promising biomarkers. This report presents compelling evidence supporting the detection of early testicular cancer by applying a set of nine microRNAs (miRNAs), establishing them as valuable serum biomarkers for diagnosis. We developed a standardized serum-based measurement protocol and conducted comprehensive statistical analyses on the dataset to underscore the diagnostic accuracy of the miRNA pool. Notably, with a sensitivity exceeding 93%, miR-21, miR-29a, and miR-106b surpass classical serum tumor markers in the context of testicular cancer. Specifically, these miRNAs are poised to enhance clinical decision-making in testicular cancer detection and hold the potential for assessing tumor growth in monitoring chemotherapy outcomes.

MicroRNA biomarkers as next-generation diagnostic tools for neurodegenerative diseases: a comprehensive review

Neurodegenerative diseases (NDs) are characterized by abnormalities within neurons of the brain or spinal cord that gradually lose function, eventually leading to cell death. Upon examination of affected tissue, pathological changes reveal a loss of synapses, misfolded proteins, and activation of immune cells-all indicative of disease progression-before severe clinical symptoms become apparent. Early detection of NDs is crucial for potentially administering targeted medications that may delay disease advancement. Given their complex pathophysiological features and diverse clinical symptoms, there is a pressing need for sensitive and effective diagnostic methods for NDs. Biomarkers such as microRNAs (miRNAs) have been identified as potential tools for detecting these diseases. We explore the pivotal role of miRNAs in the context of NDs, focusing on Alzheimer's disease, Parkinson's disease, Multiple sclerosis, Huntington's disease, and Amyotrophic Lateral Sclerosis. The review delves into the intricate relationship between aging and NDs, highlighting structural and functional alterations in the aging brain and their implications for disease development. It elucidates how miRNAs and RNA-binding proteins are implicated in the pathogenesis of NDs and underscores the importance of investigating their expression and function in aging. Significantly, miRNAs exert substantial influence on post-translational modifications (PTMs), impacting not just the nervous system but a wide array of tissues and cell types as well. Specific miRNAs have been found to target proteins involved in ubiquitination or de-ubiquitination processes, which play a significant role in regulating protein function and stability. We discuss the link between miRNA, PTM, and NDs. Additionally, the review discusses the significance of miRNAs as biomarkers for early disease detection, offering insights into diagnostic strategies.

Utilizing non-coding RNA-mediated regulation of ATP binding cassette (ABC) transporters to overcome multidrug resistance to cancer chemotherapy

Multidrug resistance (MDR) is one of the primary factors that produces treatment failure in patients receiving cancer chemotherapy. MDR is a complex multifactorial phenomenon, characterized by a decrease or abrogation of the efficacy of a wide spectrum of anticancer drugs that are structurally and mechanistically distinct. The overexpression of the ATP-binding cassette (ABC) transporters, notably ABCG2 and ABCB1, are one of the primary mediators of MDR in cancer cells, which promotes the efflux of certain chemotherapeutic drugs from cancer cells, thereby decreasing or abolishing their therapeutic efficacy. A number of studies have suggested that non-coding RNAs (ncRNAs), particularly microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), play a pivotal role in mediating the upregulation of ABC transporters in certain MDR cancer cells. This review will provide updated information about the induction of ABC transporters due to the aberrant regulation of ncRNAs in cancer cells. We will also discuss the measurement and biological profile of circulating ncRNAs in various body fluids as potential biomarkers for predicting the response of cancer patients to chemotherapy. Sequence variations, such as alternative polyadenylation of mRNA and single nucleotide polymorphism (SNPs) at miRNA target sites, which may indicate the interaction of miRNA-mediated gene regulation with genetic variations to modulate the MDR phenotype, will be reviewed. Finally, we will highlight novel strategies that could be used to modulate ncRNAs and circumvent ABC transporter-mediated MDR.

Upregulated microRNA-125b-5p in patients with asthma-COPD overlap mediates oxidative stress and late apoptosis via targeting IL6R/TRIAP1 signaling

BACKGROUND

Among patients with chronic obstructive pulmonary disease (COPD), some have features of both asthma and COPD-a condition categorized as asthma-COPD overlap (ACO). Our aim was to determine whether asthma- or COPD-related microRNAs (miRNAs) play a role in the pathogenesis of ACO.

METHODS

A total of 22 healthy subjects and 27 patients with ACO were enrolled. We selected 6 miRNAs that were found to correlate with COPD and asthma. The expression of miRNAs and target genes was analyzed using quantitative reverse-transcriptase polymerase chain reaction. Cell apoptosis and intracellular reactive oxygen species production were evaluated using flow cytometry. In vitro human monocytic THP-1 cells and primary normal human bronchial epithelial (NHBE) cells under stimuli with cigarette smoke extract (CSE) or ovalbumin (OVA) allergen or both were used to verify the clinical findings.

RESULTS

We identified the upregulation of miR-125b-5p in patients with ACO and in THP-1 cells stimulated with CSE plus OVA allergen. We selected 16 genes related to the miR-125b-5p pathway and found that IL6R and TRIAP1 were both downregulated in patients with ACO and in THP-1 cells stimulated with CSE plus OVA. The percentage of late apoptotic cells increased in the THP-1 cell culture model when stimulated with CSE plus OVA, and the effect was reversed by transfection with miR-125b-5p small interfering RNA (siRNA). The percentage of reactive oxygen species-producing cells increased in the NHBE cell culture model when stimulated with CSE plus OVA, and the effect was reversed by transfection with miR-125b-5p siRNA. In NHBE cells, siRNA transfection reversed the upregulation of STAT3 under CSE+OVA stimulation.

CONCLUSIONS

Our study revealed that upregulation of miR-125b-5p in patients with ACO mediated late apoptosis in THP-1 cells and oxidative stress in NHBE cells via targeting IL6R and TRIAP1. STAT3 expression was also regulated by miR-125b-5p.

Expression, not sequence, distinguishes miR-238 from its miR-239ab sister miRNAs in promoting longevity in Caenorhabditis elegans

MicroRNAs (miRNAs) regulate gene expression by base-pairing to target sequences in messenger RNAs (mRNAs) and recruiting factors that induce translational repression and mRNA decay. In animals, nucleotides 2-8 at the 5' end of the miRNA, called the seed region, are often necessary and sometimes sufficient for functional target interactions. MiRNAs that contain identical seed sequences are grouped into families where individual members have the potential to share targets and act redundantly. A rare exception seemed to be the miR-238/239ab family in Caenorhabditis elegans, as previous work indicated that loss of miR-238 reduced lifespan while deletion of the miR-239ab locus resulted in enhanced longevity and thermal stress resistance. Here, we re-examined these potentially opposing roles using new strains that individually disrupt each miRNA sister. We confirmed that loss of miR-238 is associated with a shortened lifespan but could detect no longevity or stress phenotypes in animals lacking miR-239a or miR-239b, individually or in combination. Additionally, dozens of genes were mis-regulated in miR-238 mutants but almost no gene expression changes were detected in either miR-239a or miR-239b mutants compared to wild type animals. We present evidence that the lack of redundancy between miR-238 and miR-239ab is independent of their sequence differences; miR-239a or miR-239b could substitute for the longevity role of miR-238 when expressed from the miR-238 locus. Altogether, these studies disqualify miR-239ab as negative regulators of aging and demonstrate that expression, not sequence, dictates the specific role of miR-238 in promoting longevity.

Profiling the polyadenylated transcriptome of extracellular vesicles with long-read nanopore sequencing

BACKGROUND

While numerous studies have described the transcriptomes of extracellular vesicles (EVs) in different cellular contexts, these efforts have typically relied on sequencing methods requiring RNA fragmentation, which limits interpretations on the integrity and isoform diversity of EV-targeted RNA populations. It has been assumed that mRNA signatures in EVs are likely to be fragmentation products of the cellular mRNA material, and the extent to which full-length mRNAs are present within EVs remains to be clarified.

RESULTS

Using long-read nanopore RNA sequencing, we sought to characterize the full-length polyadenylated (poly-A) transcriptome of EVs released by human chronic myelogenous leukemia K562 cells. We detected 443 and 280 RNAs that were respectively enriched or depleted in EVs. EV-enriched poly-A transcripts consist of a variety of biotypes, including mRNAs, long non-coding RNAs, and pseudogenes. Our analysis revealed that 10.58% of all EV reads, and 18.67% of all cellular (WC) reads, corresponded to known full-length transcripts, with mRNAs representing the largest biotype for each group (EV = 58.13%, WC = 43.93%). We also observed that for many well-represented coding and non-coding genes, diverse full-length transcript isoforms were present in EV specimens, and these isoforms were reflective-of but often in different ratio compared to cellular samples.

CONCLUSION

This work provides novel insights into the compositional diversity of poly-A transcript isoforms enriched within EVs, while also underscoring the potential usefulness of nanopore sequencing to interrogate secreted RNA transcriptomes.

Identification and verification of a prognostic signature based on a miRNA-mRNA interaction pattern in colon adenocarcinoma

The expression characteristics of non-coding RNA (ncRNA) in colon adenocarcinoma (COAD) are involved in regulating various biological processes. To achieve these functions, ncRNA and a member of the Argonaute protein family form an RNA-induced silencing complex (RISC). The RISC is directed by ncRNA, especially microRNA (miRNA), to bind the target complementary mRNAs and regulate their expression by interfering with mRNA cleavage, degradation, or translation. However, how to identify potential miRNA biomarkers and therapeutic targets remains unclear. Here, we performed differential gene screening based on The Cancer Genome Atlas dataset and annotated meaningful differential genes to enrich related biological processes and regulatory cancer pathways. According to the overlap between the screened differential mRNAs and differential miRNAs, a prognosis model based on a least absolute shrinkage and selection operator-based Cox proportional hazards regression analysis can be established to obtain better prognosis characteristics. To further explore the therapeutic potential of miRNA as a target of mRNA intervention, we conducted an immunohistochemical analysis and evaluated the expression level in the tissue microarray of 100 colorectal cancer patients. The results demonstrated that the expression level of POU4F1, DNASE1L2, and WDR72 in the signature was significantly upregulated in COAD and correlated with poor prognosis. Establishing a prognostic signature based on miRNA target genes will help elucidate the molecular pathogenesis of COAD and provide novel potential targets for RNA therapy.

Placental microRNAs relate to early childhood growth trajectories

BACKGROUND

Poor placental function is a common cause of intrauterine growth restriction, which in turn is associated with increased risks of adverse health outcomes. Our prior work suggests that birthweight and childhood obesity-associated genetic variants functionally impact placental function and that placental microRNA are associated with birthweight. To address the influence of the placenta beyond birth, we assessed the relationship between placental microRNAs and early childhood growth.

METHODS

Using the SITAR package, we generated two parameters that describe individual weight trajectories of children (0-5 years) in the New Hampshire Birth Cohort Study (NHBCS, n = 238). Using negative binomial generalized linear models, we identified placental microRNAs that relate to growth parameters (FDR < 0.1), while accounting for sex, gestational age at birth, and maternal parity.

RESULTS

Genes targeted by the six growth trajectory-associated microRNAs are enriched (FDR < 0.05) in growth factor signaling (TGF/beta: miR-876; EGF/R: miR-155, Let-7c; FGF/R: miR-155; IGF/R: Let-7c, miR-155), calmodulin signaling (miR-216a), and NOTCH signaling (miR-629).

CONCLUSIONS

Growth-trajectory microRNAs target pathways affecting placental proliferation, differentiation and function. Our results suggest a role for microRNAs in regulating placental cellular dynamics and supports the Developmental Origins of Health and Disease hypothesis that fetal environment can have impacts beyond birth.

IMPACT

We found that growth trajectory associated placenta microRNAs target genes involved in signaling pathways central to the formation, maintenance and function of placenta; suggesting that placental cellular dynamics remain critical to infant growth to term and are under the control of microRNAs. Our results contribute to the existing body of research suggesting that the placenta plays a key role in programming health in the offspring. This is the first study to relate molecular patterns in placenta, specifically microRNAs, to early childhood growth trajectory.

Basic Principles of RNA Interference: Nucleic Acid Types and In Vitro Intracellular Delivery Methods

Since its discovery in 1989, RNA interference (RNAi) has become a widely used tool for the in vitro downregulation of specific gene expression in molecular biological research. This basically involves a complementary RNA that binds a target sequence to affect its transcription or translation process. Currently, various small RNAs, such as small interfering RNA (siRNA), micro RNA (miRNA), small hairpin RNA (shRNA), and PIWI interacting RNA (piRNA), are available for application on in vitro cell culture, to regulate the cells' gene expression by mimicking the endogenous RNAi-machinery. In addition, several biochemical, physical, and viral methods have been established to deliver these RNAs into the cell or nucleus. Since each RNA and each delivery method entail different off-target effects, limitations, and compatibilities, it is crucial to understand their basic mode of action. This review is intended to provide an overview of different nucleic acids and delivery methods for planning, interpreting, and troubleshooting of RNAi experiments.

Effect of circ_0000009 on lung adenocarcinoma progression by regulating PDZD2 in a ceRNA- and RBP- dependent manner

Accumulating evidence now demonstrated that circular RNAs (circRNAs) are closely related to the pathogenesis of lung adenocarcinoma (LUAD). Through GEO2R online analysis, we screened hsa_circ_0000009 (circ_0000009) from the GEO database (GSE158695), and its expression in LUAD cancer tissues and cell lines was detected by RT-qPCR. The looping structure of circ_0000009 was tested by RNase R and actinomycin D experiments. The changes of proliferation were tested by CCK-8 or EdU assay. And the changes of apoptosis in A549 and H1299 cells were measured via flow cytometry. The A549 BALB/c tumor model was established to evaluate the influence of circ_0000009 on LUAD cell growth in vivo. In addition, experiments connected with ceRNA direction (mainly including bioinformatics prediction and luciferase reporter assay) and RNA Binding Protein (RBP) direction (mainly including RNA pull-down assay, RIP assay and mRNA stability assay) were further developed to reveal the regulatory mechanism of circ_0000009. The gene and protein levels in this project were assessed by RT-qPCR and western blotting analysis, respectively. The data manifested that circ_0000009 was in low expression in LUAD. The in vitro and in vivo experiments threw light on that overexpression of circ_0000009 dramatically suppressing LUAD tumorigenesis. Mechanistically, circ_0000009 promoted the expression of PDZD2 by sponging miR-154-3p. Furthermore, circ_0000009 stabilized PDZD2 by recruiting IGF2BP2. This study illustrated the mechanism that overexpressing of circ_0000009 suppressed LUAD progression by upregulating PDZD2 expression, providing an original treatment direction for LUAD.

Circular RNAs in endometrial carcinoma (Review)

As one of the leading causes of death in women in Western developed countries, endometrial carcinoma (EC) is a common gynecological malignant tumor that seriously threatens women's health. In recent years, a trend has emerged of EC being manifested in younger women, and its overall incidence is gradually rising. Circular RNAs (circRNAs) are novel endogenous transcripts that have limited ability to encode proteins due to their covalent closed‑loop structure, which differs from that of other types of RNA. A growing body of evidence has demonstrated that circRNAs fulfill an important role in lung cancer, gastric cancer, breast cancer, EC and other malignant tumor types, and they can affect the occurrence and development of these malignancies through a variety of pathways, further demonstrating the potential of circRNAs as molecular biomarkers for the diagnosis, treatment and prognosis of malignant tumors. The purpose of the present review is to summarize the current understanding of the biogenesis and effects of circRNAs, and to discuss the expression, function and underlying mechanism of circRNAs in EC in order to identify potential novel biomarkers.

Dual function miR-205 is positively associated with ER and negatively with five-year survival in breast cancer patients

BACKGROUND

Precise molecular characterization of breast cancer, especially triple negative (TNBC) as the most lethal subtype, is needed to stratify patients for the individual treatment approach. MicroRNA-205 (miR-205) has tumor-suppressive and oncogenic functions across different cancers. Therefore, miR-205 might have a different role in TNBC and estrogen receptor (ER) positive BC. Our aim was to investigate how miR-205 expression is associated with ER/progesteron receptor status, clinical parameters, pathohistological characteristics of BC, and survival of patients METHODS: We determined miR-205 relative expressions in 73 primary breast tumors (50 TNBC and 23 ER+) by quantitative Real-time polymerase chain reaction (qPCR) and compared it to clinicopathological characteristics and outcome.

RESULTS

The highest levels of miR-205 were in the ER+ /PR+ group, and the lowest in the TNBC group (p = 0.009). Significantly higher levels of miR-205 were also observed in the ER+ compared with the ER-negative group, regardless of the PR status (p = 0.002). Low miR-205 expression level was associated with prognostic stage III in TNBC samples (p = 0.049). Patients who received adjuvant chemotherapy had significantly lower levels of miR-205 (p = 0.016). Patients who received hormone therapy had significantly higher levels of miR-205 (p = 0.007). The low-miR-205 patients had significantly higher 5-year survival rates (p = 0.041).

CONCLUSION

The expression of miR-205 in BC is subtype-specific and high expression is associated with the ER+ tumors. The miR-205 expression might be a useful marker of TNBC progression. High miR-205 expression had a detrimental effect on BC patient outcome. Our results indicate that miR-205 might be utilized in clinical practice as a biomarker and an adjunct parameter for the selection of the most effective therapeutic modality.

The limits of human microRNA annotation have been met

Over the last few years, the number of microRNAs in the human genome has become a controversially debated issue. Several publications reported thousands of putative novel microRNAs not included in the curated microRNA gene database MirGeneDB and the repository miRBase. Recently, by using sequencing of ∼300 human tissues and cell lines, the human RNA atlas, an expanded inventory of human RNA annotations, was published, reporting thousands of putative microRNAs. We, the developers of established microRNA prediction tools and hosts of MirGeneDB, raise concerns about the frequently applied prediction and functional validation strategies, briefly discussing the drawbacks of false positive detections. By means of quantifying well-established biogenesis-derived features, we show that the reported novel microRNAs essentially represent false-positives and argue that the human microRNA complement, at about 550 microRNA genes, is already near complete. Output of available tools must be curated as false predictions will misguide scientists looking for biomarkers or therapeutic targets.

Tumor Suppressor microRNAs in Gastrointestinal Cancers: A Mini-Review

BACKGROUND

Gastrointestinal (GI) cancer is associated with a group of cancers affecting the organs in the GI tract, with a high incidence and mortality rate. This type of cancer development involves a series of molecular events that arise by the dysregulation of gene expressions and microRNAs (miRNAs).

OBJECTIVES

This mini-review focuses on elucidating the mechanism of tumor suppressor miRNA-mediated oncogenic gene silencing, which may contribute to a better understanding of miRNA-mediated gene expression regulation of cell cycle, proliferation, invasion, and apoptosis in GI cancers. In this review, the biological significance of tumor suppressor miRNAs involved in gastrointestinal cancers is briefly explained.

METHODS

The articles were searched with the keywords 'miRNA', 'gastrointestinal cancers', 'esophageal cancer', 'gastric cancer', 'colorectal cancer', 'pancreatic cancer', 'liver cancer', and 'gall bladder cancer' from the Google Scholar and PubMed databases. A total of 71 research and review articles have been collected and referred for this study.

RESULTS

This review summarises recent research enhancing the effectiveness of miRNAs as novel prognostic, diagnostic, and therapeutic markers for GI cancer treatment strategies. The expression pattern of various miRNAs has been dysregulated in GI cancers, which are associated with proliferation, cell cycle regulation, apoptosis, migration, and invasion.

CONCLUSION

The role of tumor suppressor miRNAs in the negative regulation of oncogenic gene expression was thoroughly explained in this review. Its potential role as a microRNA therapeutic candidate is also discussed. Profiling and regulating tumor suppressor miRNA expression in gastrointestinal cancers using miRNA mimics could be used as a prognostic, diagnostic, and therapeutic marker, as well as an elucidating molecular therapeutic approach to tumor suppression.

AGO-RBP crosstalk on target mRNAs: Implications in miRNA-guided gene silencing and cancer

MicroRNAs (miRNAs) and RNA-binding proteins (RBPs) are important regulators of mRNA translation and stability in eukaryotes. While miRNAs can only bind their target mRNAs in association with Argonaute proteins (AGOs), RBPs directly bind their targets either as single entities or in complex with other RBPs to control mRNA metabolism. miRNA binding in 3' untranslated regions (3' UTRs) of mRNAs facilitates an intricate network of interactions between miRNA-AGO and RBPs, thus determining the fate of overlapping targets. Here, we review the current knowledge on the interplay between miRNA-AGO and multiple RBPs in different cellular contexts, the rules underlying their synergism and antagonism on target mRNAs, as well as highlight the implications of these regulatory modules in cancer initiation and progression.

Construction of five microRNAs prognostic markers and a prognostic model for clear cell renal cell carcinoma

Background

To determine the role of miRNA in the progression and outcome of renal clear cell carcinoma (ccRCC), establish a model for predicting outcome in patients with ccRCC and verify it using a Cox regression model. The miRNA target genes were predicted to understand their biological functions.

Methods

The microRNAs of 71 normal tissues and 545 tumor tissues were downloaded from TCGA (https://tcga-data.nci.nih.gov/tcga/). We also downloaded 537 clinical materials from this website. The miRNA difference analysis was carried out. A prognostic model was constructed using differential miRNA. The model was verified using Cox survival analysis, receiver operator characteristic (ROC), and independent predictive analysis.

Results

MiR-130b-3p, miR-365b-3p, miR-149-5p, miR-155-5p, and miR-144-5p can be used as independent prognostic indicators. We also analyzed the related functions of the target gene and found that target genes of miRNAs are involved in the signal pathways of some tumors, including cholesterol metabolism, HIF-1 signal pathway, focus adhesion, the Rap1 signal pathway, and hepatitis C.

Conclusions

The prognostic model constructed using five miRNAs is an independent and accurate factor. These miRNAs target genes are involved in regulating a variety of tumorigenesis and signal pathways. Therefore, we have reason to believe that the regulation of signal pathways by miRNA may play a critical role in the occurrence, development, and outcome of ccRCC, provide a new therapeutic target for ccRCC, and improve outcomes.

Screening Analysis of Platelet miRNA Profile Revealed miR-142-3p as a Potential Biomarker in Modeling the Risk of Acute Coronary Syndrome

Transcriptome analysis constitutes one of the major methods of elucidation of the genetic basis underlying the pathogenesis of various diseases. The post-transcriptional regulation of gene expression is mainly provided by microRNAs. Their remarkable stability in biological fluids and their high sensitivity to disease alteration indicates their potential role as biomarkers. Given the high mortality and morbidity of cardiovascular diseases, novel predictive biomarkers are sorely needed. Our study focuses for the first time on assessing potential biomarkers of acute coronary syndrome (ACS) based on the microRNA profiles of platelets. The study showed the overexpression of eight platelet microRNAs in ACS (miR-142-3p; miR-107; miR-338-3p, miR-223-3p, miR-21-5p, miR-130b-3p, miR-301a-3p, miR-221-3p) associated with platelet reactivity and functionality. Our results show that the combined model based on miR-142-3p and aspartate transaminase reached 82% sensitivity and 88% specificity in the differentiation of the studied groups. Furthermore, the analyzed miRNAs were shown to cluster into two orthogonal groups, regulated by two different biological factors. Bioinformatic analysis demonstrated that one group of microRNAs may be associated with the physiological processes of platelets, whereas the other group may be linked to platelet-vascular environment interactions. This analysis paves the way towards a better understanding of the role of platelet microRNAs in ACS pathophysiology and better modeling of the risk of ACS.

Life of RISC: Formation, action, and degradation of RNA-induced silencing complex

Small RNAs regulate a wide variety of biological processes by repressing the expression of target genes at the transcriptional and post-transcriptional levels. To achieve these functions, small RNAs form RNA-induced silencing complex (RISC) together with a member of the Argonaute (AGO) protein family. RISC is directed by its bound small RNA to target complementary RNAs and represses their expression through mRNA cleavage, degradation, and/or translational repression. Many different factors fine-tune RISC activity and stability-from guide-target RNA complementarity to the recruitment of other protein partners to post-translational modifications of RISC itself. Here, we review recent progress in understanding RISC formation, action, and degradation, and discuss new, intriguing questions in the field.

Functional characterization of miR-708 microRNA in telomerase positive and negative human cancer cells

Activation of a telomere length maintenance mechanism (TMM), including telomerase and alternative lengthening of telomeres (ALT), is essential for replicative immortality of tumor cells, although its regulatory mechanisms are incompletely understood. We conducted a microRNA (miRNA) microarray analysis on isogenic telomerase positive (TEP) and ALT cancer cell lines. Amongst nine miRNAs that showed difference in their expression in TEP and ALT cancer cells in array analysis, miR-708 was selected for further analysis since it was consistently highly expressed in a large panel of ALT cells. miR-708 in TEP and ALT cancer cells was not correlated with C-circle levels, an established feature of ALT cells. Its overexpression induced suppression of cell migration, invasion, and angiogenesis in both TEP and ALT cells, although cell proliferation was inhibited only in TEP cells suggesting that ALT cells may have acquired the ability to escape inhibition of cell proliferation by sustained miR-708 overexpression. Further, cell proliferation regulation in TEP cells by miR708 appears to be through the CARF-p53 pathway. We demonstrate here that miR-708 (i) is the first miRNA shown to be differentially regulated in TEP and ALT cancer cells, (ii) possesses tumor suppressor function, and (iii) deregulates CARF and p21^WAF1-mediated signaling to limit proliferation in TEP cells.

SPINT1-AS1 Drives Cervical Cancer Progression via Repressing miR-214 Biogenesis

Accumulating evidences have revealed the dysregulated expressions and critical roles of non-coding RNAs in various malignancies, including cervical cancer. Nevertheless, our knowledge about the vast majority of non-coding RNAs is still lacking. Here we identified long non-coding RNA (lncRNA) SPINT1-AS1 as a novel cervical cancer-associated lncRNA. SPINT1-AS1 was increased in cervical cancer and correlated with advanced stage and poor prognosis. SPINT1-AS1 was a direct downstream target of miR-214, a well-known tumor suppressive microRNA (miRNA) in cervical cancer. Intriguingly, SPINT1-AS1 was also found to repress miR-214 biogenesis via binding DNM3OS, the primary transcript of miR-214. The interaction between SPINT1-AS1 and DNM3OS repressed the binding of DROSHA and DGCR8 to DNM3OS, blocked DNM3OS cleavage, and therefore repressed mature miR-214 biogenesis. The expression of SPINT1-AS1 was significantly negatively correlated with miR-214 in cervical cancer tissues, supporting the reciprocal repression between SPINT1-AS1 and miR-214 in vivo. Through downregulating mature miR-214 level, SPINT1-AS1 upregulated the expression of β-catenin, a target of miR-214. Thus, SPINT1-AS1 further activated Wnt/β-catenin signaling in cervical cancer. Functionally, SPINT1-AS1 drove cervical cancer cellular proliferation, migration, and invasion in vitro, and also tumorigenesis in vivo. Deletion of the region mediating the interaction between SPINT1-AS1 and DNM3OS, overexpression of miR-214, and inhibition of Wnt/β-catenin signaling all reversed the roles of SPINT1-AS1 in cervical cancer. Collectively, these findings identified SPINT1-AS1 as a novel cervical cancer-associated oncogenic lncRNA which represses miR-214 biogenesis and activates Wnt/β-catenin signaling, highlighting its potential as prognostic biomarker and therapeutic target for cervical cancer.

Regulatory noncoding RNAs: functions and applications in health and disease

Science is facing a new RNA world that is shaping our knowledge, and we are discovering a new horizon in molecular biology. New technologies revealed thousands and thousands of new RNAs, most of them located in what was once known as the "dark matter of DNA". They are functional regulatory RNAs and do not code for proteins, and they orchestrate the cellular function according to the changes needed. These noncoding RNAs are ubiquitous, and they are present from viruses to humans. In this Virtual Issue, The FEBS Journal features a collection of recent articles on long noncoding RNAs, microRNAs, and circular RNAs. It gives a broad perspective regarding their role in vascular diseases, ocular diseases, immune cell development and homeostasis, inflammation, production of extracellular matrix, and cancer. Furthermore, review-type articles highlight the potential use of noncoding RNAs in a wide range of applications.

Flavonoids Overcome Drug Resistance to Cancer Chemotherapy by Epigenetically Modulating Multiple Mechanisms

Drug resistance is the major reason accounting for the treatment failure in cancer chemotherapy. Dysregulation of the epigenetic machineries is known to induce chemoresistance. It was reported that numerous genes encoding the key mediators in cancer proliferation, apoptosis, DNA repair, and drug efflux are dysregulated in resistant cancer cells by aberrant DNA methylation. The imbalance of various enzymes catalyzing histone post-translational modifications is also known to alter chromatin configuration and regulate multiple drug resistance genes. Alteration in miRNA signature in cancer cells also gives rise to chemoresistance. Flavonoids are a large group of naturally occurring polyphenolic compounds ubiquitously found in plants, fruits, vegetables and traditional herbs. There has been increasing research interest in the health-promoting effects of flavonoids. Flavonoids were shown to directly kill or re-sensitize resistant cancer cells to conventional anticancer drugs by epigenetic mechanisms. In this review, we summarize the current findings of the circumvention of drug resistance by flavonoids through correcting the aberrant epigenetic regulation of multiple resistance mechanisms. More investigations including the evaluation of synergistic anticancer activity, dosing sequence effect, toxicity in normal cells, and animal studies, are warranted to establish the full potential of the combination of flavonoids with conventional chemotherapeutic drugs in the treatment of cancer with drug resistance.

Oncogenesis and Tumor Inhibition by MicroRNAs and its Potential Therapeutic Applications: A Systematic Review

MicroRNAs appear as small molecule modifiers, which improve many new findings and mechanical illustrations for critically important biological phenomena and pathologic events. The best-characterized non-coding RNA family consists of about 2600 human microRNAs. Rich evidence has revealed their crucial importance in maintaining normal development, differentiation, growth control, aging, modulation of cell survival or apoptosis, as well as migration and metastasis as microRNAs dysregulation leads to cancer incidence and progression. By far, microRNAs have recently emerged as attractive targets for therapeutic intervention. The rationale for developing microRNA therapeutics is based on the premise that aberrantly expressed microRNAs play a significant role in the emergence of a variety of human diseases ranging from cardiovascular defects to cancer, and that repairing these microRNA deficiencies by either antagonizing or restoring microRNA function may yield a therapeutic benefit. Although microRNA antagonists are conceptually similar to other inhibitory therapies, improving the performance of microRNAs by microRNA replacement or inhibition that is a less well- described attitude. In this assay, we have condensed the last global knowledge and concepts regarding the involvement of microRNAs in cancer emergence, which has been achieved from the previous studies, consisting of the regulation of key cancer-related pathways, such as cell cycle control and the DNA damage response and the disruption of profile expression in human cancer. Here, we have reviewed the special characteristics of microRNA replacement and inhibition therapies and discussed explorations linked with the delivery of microRNA mimics in turmeric cells. Besides, the achievement of biomarkers based on microRNAs in clinics is considered as novel non-invasive biomarkers in diagnostic and prognostic assessments.

The mechanisms and functions of microRNAs in mediating the fate determinations of human spermatogonial stem cells and Sertoli cells

Human spermatogonial stem cells (SSCs) and Sertoli cells might have the applications in reproduction and regenerative medicine. Abnormal spermatogenesis results in male infertility, which seriously affects human reproduction and health. Spermatogenesis depends on the epigenetic and genetic regulation of male germ cells and somatic cells. A number of microRNAs (miRNAs) have been identified in human testicular tissues, and they are closely related to male fertility. Significantly, we and peers have recently demonstrated that numerous miRNAs are essential for regulating the self-renewal and apoptosis of human SSCs and Sertoli cells through controlling their mRNA and lncRNA targets. In this review, we critically discuss these findings regarding the important functions and mechanisms of miRNAs in mediating the fate determinations of human SSCs and Sertoli cells. Meanwhile, we illustrate the regulatory networks for miRNAs by forming the upstream and downstream regulators of mRNAs and lncRNAs in human SSCs, and we address that miRNAs regulate the decisions of Sertoli cells by targeting genes and via N6-methyladenosine (m6A). We also point out the future directions for further studies on this field. This review could offer an update on novel molecular targets for treating male infertility and new insights into epigenetic regulation of human spermatogenesis.

Bioinformatic analysis and validation of microRNA-508-3p as a protective predictor by targeting NR4A3/MEK axis in pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) featured a debilitating progressive disorder. Here, we intend to determine diagnosis‐valuable biomarkers for PAH and decode the fundamental mechanisms of the biological function of these markers. Two mRNA microarray profiles (GSE70456 and GSE117261) and two microRNA microarray profiles (GSE55427 and GSE67597) were mined from the Gene Expression Omnibus platform. Then, we identified the differentially expressed genes (DEGs) and differentially expressed miRNAs (DEMs), respectively. Besides, we investigated online miRNA prediction tools to screen the target gene of DEMs. In this study, 185 DEGs and three common DEMs were screened as well as 1266 target genes of the three DEMs were identified. Next, 16 overlapping dysregulated genes from 185 DEGs and 1266 target gene were obtained. Meanwhile, we constructed the miRNA gene regulatory network and determined miRNA‐508‐3p‐NR4A3 pair for deeper exploring. Experiment methods verified the functional expression of miR‐508‐3p in PAH and its signalling cascade. We observed that ectopic miR‐508‐3p expression promotes proliferation and migration of pulmonary artery smooth muscle cell (PASMC). Bioinformatic, dual‐luciferase assay showed NR4A3 represents directly targeted gene of miR‐508‐3p. Mechanistically, we demonstrated that down‐regulation of miR‐508‐3p advances PASMC proliferation and migration via inducing NR4A3 to activate MAPK/ERK kinase signalling pathway. Altogether, our research provides a promising diagnosis of predictor and therapeutic avenues for patients in PAH.

CSDE1 attenuates microRNA-mediated silencing of PMEPA1 in melanoma

MicroRNAs and RNA-binding proteins (RBPs) primarily target the 3' UTR of mRNAs to control their translation and stability. However, their co-regulatory effects on specific mRNAs in physiology and disease are yet to be fully explored. CSDE1 is an RBP that promotes metastasis in melanoma and mechanisms underlying its oncogenic activities need to be completely defined. Here we report that CSDE1 interacts with specific miRNA-induced silencing complexes (miRISC) in melanoma. We find an association of CSDE1 with AGO2, the essential component of miRISC, which is facilitated by target mRNAs and depends on the first cold shock domain of CSDE1. Both CSDE1 and AGO2 bind to 3' UTR of PMEPA1. CSDE1 counters AGO2 binding, leading to an increase of PMEPA1 expression. We also identify a miRNA, miR-129-5p, that represses PMEPA1 expression in melanoma. Collectively, our results show that PMEPA1 promotes tumorigenic traits and that CSDE1 along with miR-129-5p/AGO2 miRISC act antagonistically to fine-tune PMEPA1 expression toward the progression of melanoma.

Placental microRNA expression associates with birthweight through control of adipokines: results from two independent cohorts

MicroRNAs are non-coding RNAs that regulate gene expression post-transcriptionally. In the placenta, the master regulator of foetal growth and development, microRNAs shape the basic processes of trophoblast biology and specific microRNA have been associated with foetal growth. To comprehensively assess the role of microRNAs in placental function and foetal development, we have performed small RNA sequencing to profile placental microRNAs from two independent mother-infant cohorts: the Rhode Island Child Health Study (n = 225) and the New Hampshire Birth Cohort Study (n = 317). We modelled microRNA counts on infant birthweight percentile (BWP) in each cohort, while accounting for race, sex, parity, and technical factors, using negative binomial generalized linear models. We identified microRNAs that were differentially expressed (DEmiRs) with BWP at false discovery rate (FDR) less than 0.05 in both cohorts. hsa-miR-532-5p (miR-532) was positively associated with BWP in both cohorts. By integrating parallel whole transcriptome and small RNA sequencing in the RICHS cohort, we identified putative targets of miR-532. These targets are enriched for pathways involved in adipogenesis, adipocytokine signalling, energy metabolism, and hypoxia response, and included Leptin, which we further demonstrated to have a decreasing expression with increasing BWP, particularly in male infants. Overall, we have shown a robust and reproducible association of miR-532 with BWP, which could influence BWP through regulation of adipocytokines Leptin and Adiponectin.

Computational prediction of miRNA/mRNA duplexomes at the whole human genome scale reveals functional subnetworks of interacting genes with embedded miRNA annealing motifs

Perfect annealing between microRNAs (miRNAs) and messenger RNAs (mRNAs) was computationally searched at a broad scale in the human genome to determine whether theoretical pairing is restrictively represented in functional subnetworks or is randomly distributed. Massive RNA interference (RNAi) pairing motifs in genes constitute a remarkable subnetwork that displays highly genetically and biochemically interconnected genes. These analyses show unexpected repertoires of genes defined by their congruence in comatching with miRNAs at numerous sites and by their interconnection based on protein/protein interactions or proteins regulating the activity of others. This offers insights into the putatively coregulated homeostasis of large networks of genes by RNAi, whereas other networks seem to be independent of this regulatory mode. Genes accordingly defined by theoretical RNAi pairing cluster mainly in subnetworks related to cellular, metabolic and developmental processes and their regulation. Indeed, genes harboring numerous potential sites of hybridization with miRNAs are highly enriched with GO terms depicting the abovementioned processes and are grouped in a subnetwork of genes that are significantly more highly connected than they would be according to a random distribution. The significant number of interacting genes that present numerous potential comatches with miRNAs suggests that they may be under the control of the integrative and concerted action of multiple miRNAs.

In vivo CRISPR screening for phenotypic targets of the mir-35-42 family in C. elegans

In this study, Yang et al. devised a novel strategy to test the phenotypic impact of individual microRNA–target interactions by disrupting each predicted miRNA-binding site by CRISPR–Cas9 genome editing in C. elegans. They developed a multiplexed negative selection screening approach, in which edited loci are deep sequenced, and candidate sites are prioritized based on apparent selection pressure against mutations that disrupt miRNA binding.

Identifying miRNA target genes is difficult, and delineating which targets are the most biologically important is even more difficult. We devised a novel strategy to test the phenotypic impact of individual microRNA–target interactions by disrupting each predicted miRNA-binding site by CRISPR–Cas9 genome editing in C. elegans. We developed a multiplexed negative selection screening approach in which edited loci are deep sequenced, and candidate sites are prioritized based on apparent selection pressure against mutations that disrupt miRNA binding. Importantly, our screen was conducted in vivo on mutant animals, allowing us to interrogate organism-level phenotypes. We used this approach to screen for phenotypic targets of the essential mir-35-42 family. By generating 1130 novel 3′UTR alleles across all predicted targets, we identified egl-1 as a phenotypic target whose derepression partially phenocopies the mir-35-42 mutant phenotype by inducing embryonic lethality and low fecundity. These phenotypes can be rescued by compensatory CRISPR mutations that retarget mir-35 to the mutant egl-1 3′UTR. This study demonstrates that the application of in vivo whole organismal CRISPR screening has great potential to accelerate the discovery of phenotypic negative regulatory elements in the noncoding genome.

MiR-140 Resensitizes Cisplatin-Resistant NSCLC Cells to Cisplatin Treatment Through the SIRT1/ROS/JNK Pathway

Background

Although cisplatin is an effective chemotherapeutic drug that is commonly used for non-small-cell lung cancer (NSCLC) treatment, the drug resistance usually occurs during the long-term use of it. It is urgent to develop strategies to reduce the resistance of NSCLC cells to cisplatin.

Methods

Cisplatin-resistant NSCLC cell lines (PC9/R and A549/R) were acquired through long-term exposure of PC9 and A549 cells to cisplatin. QRT-PCR analysis was performed to compare the expression of miR-140 between routine NSCLC cells and cisplatin-resistant NSCLC cells. CCK-8 assay was used to evaluate the effect of miR-140 on the sensitivity of PC9/R and A549/R to cisplatin. Western blot assay and luciferase reporter assay were used to confirm the regulation of miR-140 on SIRT1. Western blot and flow cytometry analysis were performed to evaluate the effect of miR-140 on the apoptosis pathway induced by cisplatin.

Results

PC9/R and A549/R exhibited obviously lower sensitivity compared to their parental PC9 and A549 cells, respectively. Furthermore, PC9/R and A549/R cells expressed significantly lower levels of miR-140 compared to their parental PC9 and A549 cells, respectively. However, transfection with miR-140 mimics significantly resensitized the PC9/R and A549/R to cisplatin-induced cytotoxicity. In the mechanism research, we confirmed that SIRT1 was overexpressed and was targeted by miR-140 in PC9/R and A549/R. Furthermore, overexpression of SIRT1 was responsible for the resistance to cisplatin in PC9/R and A549/R cells. Transfection with miR-140 was able to inhibit the expression of SIRT1 and thus inhibited the SIRT1/ROS/JNK pathway. As a result, the PC9/R and A549/R cells restored the sensitivity to cisplatin-induced apoptosis.

Conclusion

MiR-140 resensitizes cisplatin-resistant NSCLC cells to cisplatin treatment through the SIRT1/ROS/JNK pathway.

Whether miR-4293 rs12220909 variant affects cancer susceptibility: evidence from 11255 subjects

Background: miR-4293 rs12220909 polymorphism was reported associated with tumorigenesis, but the results are controversial. Thus, we planned to verify and obtain precise results.Methods: Databases were searched and reviewed up to November, 2019. Case-control studies which concern about the association between cancer risks and miR-4293 polymorphisms were all enrolled. The odds ratios (ORs) and 95% confidence intervals (CIs) calculated by the Z test were used to assess the underlying links. We also prospected how the miR-4293 impacts biological process through its target genes.Result: Finally, there are seven independent studies meet the enrolled criteria, along with 5147 cases and 6108 healthy controls. We revealed that there is a significant decrease effect of miR-4293 rs12220909 to cancer risks in heterozygote genetic model (BA vs. AA: OR = 0.857, p = .032), the similar results were also uncovered in PB control group, lung cancer and the studies conform to HWE. Results from GO items and KEGG pathway analysis illustrated that myeloid cell development, transcription factor complex, RNA polymerase II regulatory region DNA binding were regulated by miR-4293.Conclusion: In summary, our meta-analysis chase down heterozygote rs12220909 polymorphism of miR-4293 is a protective factor to cancer initiation, especially for lung cancer.

Osteoclast signaling-targeting miR-146a-3p and miR-155-5p are downregulated in Paget's disease of bone

MicroRNA (miRs) are small, non-coding RNA that post-transcriptionally regulate DNA expression. We hypothesized that specific miR profiles may be a feature of overactive osteoclasts in Paget's disease of bone (PDB), a disorder characterized by an increased and disorganized bone remodeling that typically begins with excessive bone resorption. We compared the expression profile of 13 miRs in human osteoclasts differentiated in vitro from peripheral blood mononuclear cells (PBMCs) of patients with PDB (n = 10) or age- and sex- matched healthy subjects (n = 10). We selected 13 miRs for testing, on the basis of their previously reported roles either in human osteoclast differentiation, in bone diseases, or in osteoclast important signaling pathways. From those expression results, 3 miRNAs were further selected for in-vitro studies aiming at modulating miR expression in human cord blood monocyte derived osteoclasts: 2 miRs (miR-146a-3p and miR-155-5p) whose expression was significantly reduced in pagetic osteoclasts, as well as miRNA-133a-3p, stable in PDB relative to controls, but with known regulatory importance within osteoclasts. We demonstrated a positive (miR-133a-3p) or negative (miR-155-5p, miR-146a-3p) impact of those miRs on the formation of osteoclasts and/or their bone resorption capacity in this human model. Signaling pathways were significantly affected, including p38 MAP-kinase (miR-133a-3p), RANKL-induced TRAF6/NFκB signaling (miR-146a-3p), and MITF expression (miR-155-5p). Osteoclast miRNA profiles might have an important value to yield significant new insights into the osteoclast phenotype in PDB and in other bone diseases with hyperactive osteoclasts.

CircRNA WHSC1 targets the miR-646/NPM1 pathway to promote the development of endometrial cancer

Circular RNAs (circRNAs) play important roles in human cancer progression. Their high stability and tissue specificity make circRNAs important molecular targets for clinical diagnosis, treatment and prognosis. However, the functions and molecular mechanisms of circRNA WHSC1 in endometrial cancer are unknown. CircWHSC1 expression in normal endometrial and endometrial cancer tissues was detected using PCR. Overexpression or knockdown of circWHSC1 in endometrial cancer cell lines HEC‐1B or Ishikawa, respectively, cell function experiments were used to detect the impact of circWHSC1 on endometrial cancer cells. A nude mouse xenograft model was used to detect changes in tumorigenesis of HEC‐1B cells after circWHSC1 overexpression. Bioinformatics and dual luciferase reporter gene technology were used to predict and validate the sponging ability of circWHSC1 on microRNAs. Gene expression changes were detected by using Western blotting. CircWHSC1 expression was increased in endometrial cancer tissues. CircWHSC1 overexpression promoted the proliferation, migration and invasion of endometrial cancer cells and decreased apoptosis. CircWHSC1 knockdown had the opposite effect. CircWHSC1 overexpressed nude mice showed increased tumorigenicity. Bioinformatics predicted that circWHSC1 binds to miR‐646, which was confirmed using luciferase reporter gene assays. High expression of miR‐646 could reverse the effect of circWHSC1 on endometrial cancer cells. Western blotting showed increased or decreased levels of nucleophosmin 1 (NPM1), an miR‐646 downstream target, after circWHSC1 overexpression or knockdown, respectively. CircWHSC1 promotes endometrial cancer development through sponging miR‐646 and targeting NPM1.

Role of Connexins 30, 36, and 43 in Brain Tumors, Neurodegenerative Diseases, and Neuroprotection

Gap junction (GJ) channels and their connexins (Cxs) are complex proteins that have essential functions in cell communication processes in the central nervous system (CNS). Neurons, astrocytes, oligodendrocytes, and microglial cells express an extraordinary repertory of Cxs that are important for cell to cell communication and diffusion of metabolites, ions, neurotransmitters, and gliotransmitters. GJs and Cxs not only contribute to the normal function of the CNS but also the pathological progress of several diseases, such as cancer and neurodegenerative diseases. Besides, they have important roles in mediating neuroprotection by internal or external molecules. However, regulation of Cx expression by epigenetic mechanisms has not been fully elucidated. In this review, we provide an overview of the known mechanisms that regulate the expression of the most abundant Cxs in the central nervous system, Cx30, Cx36, and Cx43, and their role in brain cancer, CNS disorders, and neuroprotection. Initially, we focus on describing the Cx gene structure and how this is regulated by epigenetic mechanisms. Then, the posttranslational modifications that mediate the activity and stability of Cxs are reviewed. Finally, the role of GJs and Cxs in glioblastoma, Alzheimer's, Parkinson's, and Huntington's diseases, and neuroprotection are analyzed with the aim of shedding light in the possibility of using Cx regulators as potential therapeutic molecules.

Role of MicroRNA-30c in cancer progression

MicroRNAs (miRNAs or miRs) is a non-coding small RNA of a type of 18~24 nucleotide-regulated gene that has been discovered in recent years. It mainly degrades the target gene mRNA or inhibits its translation process through the complete or incomplete bindings with 3'UTR of target genes, followed by the regulation of individual development, apoptosis, proliferation, differentiation and other life activities through the post-transcriptional regulation. Among many miRNAs, the microRNA family, miR-30, plays diverse roles in these key process of neoplastic transformation, metastasis, and clinical outcomes in different cancer progression. As key member of miR-30, miR-30c is regulated by oncogenic transcription factors and cancer progression related genes. Recently, numerous studies have demonstrated that the aberrant expression of miR-30c was significantly associated with the majority of human cancer progression. In this review, the diverse roles of miR-30c in different cancer progression such as the cellular and molecular mechanisms, the potential applications in clinics were summarized to speculate the benefits of miR-30c over-expression in cancer treatment and prognosis.

miR-936 Suppresses Cell Proliferation, Invasion, and Drug Resistance of Laryngeal Squamous Cell Carcinoma and Targets GPR78

MicroRNAs (miRs) play important roles in tumor progression. miR-936 has been reported to suppress cell invasion and proliferation of glioma and non-small cell lung cancer. Nevertheless, the function of miR-936 in laryngeal squamous cell carcinoma (LSCC) remains undiscovered. Hence, our study was to investigate the role of miR-936 in LSCC. In our present research, we have testified that miR-936 was substantially downregulated in LSCC tissues compared with adjacent normal tissues. Furthermore, miR-936 could inhibit proliferation, migration and invasion, and improve the sensitivity to doxorubicin and cisplatin of LSCC cells. Additionally, luciferase reporter assays were performed to confirm that GPR78 was a novel target of miR-936, and the protein expression of GPR78 was obviously inhibited by miR-936 in LSCC cells. In summary, our study indicates that the miR-936/GPR78 axis could be both a diagnostic marker and a therapeutic target for LSCC.

Plasma MicroRNA as a novel diagnostic

MicroRNAs (miRNAs) are small, single-stranded, endogenous, non-coding RNAs necessary for proper gene expression. Their mechanism of action controls translation by base-pairing with target messenger RNA (mRNAs) thus leading to translation blockage or mRNA degradation. Many studies have shown that miRNAs play pivotal roles in cancer, cardiovascular disease and neurodegenerative disorders. The lack of blood-derived biomarkers and those markers of poor specificity and sensitivity significantly impact the ability to diagnose in general and at early disease stage specifically. As such, new, non-invasive and quantifiable biomarkers are needed. As post-transcriptional regulators of gene expression, miRNAs have been confirmed to be notably stable in cells, tissues and body fluids. These and other advantages make miRNAs ideal candidates as potential biomarkers and early experimental findings support this finding. This review examines the use of miRNAs as biomarkers in cancer, neurodegenerative, cardiovascular and liver disease and viral infection.

Does miR-618 rs2682818 variant affect cancer susceptibility? Evidence from 10 case-control studies

Piles of evidence have supported the relationship between miR-618 rs2682818 polymorphism and tumorigenesis, but the conclusion remains inconsistent. In the present study, we conducted a meta-analysis to sniff out the potential risk between miR-618 rs2682818 and overall cancers. Crude odds ratios (ORs) and 95% confidence intervals (CIs) analyzed by Z-test were employed to estimate the potential interrelation in five genetic models. We also prospected how the rs2682818 affects the second structure of miR-618. Finally, 10 independent studies meet the enrolled criteria, along with 4099 cancer cases and 5057 healthy controls. Overall, no exceeding interrelation was sniffed out in the pooled data among five inherited models, as well as stratified analyses. Whereas, the enhanced cancer risk of miR-618 rs2682818 variant stratified by breast cancer was revealed, in heterozygote genetic model (AC vs. CC: OR = 1.291, 95%CI = 1.012-1.648, P = 0.040) and dominant contrast model (AA + AC vs. CC: OR = 1.280, 95%CI = 1.009-1.623, P = 0.042). The second structure prediction result shown that the mutant A allele might change the first stem-loop of miR-618, and the free energy of it would turn from -39.1 to -35.1 kcal/mol. All in all, our meta-analysis had successfully chased down that miR-618 rs2682818 polymorphism is not linked with overall cancer risk, but in the dominant genotype of breast cancer.

miR-200c-3p Suppresses the Proliferative, Migratory, and Invasive Capacities of Nephroblastoma Cells via Targeting FRS2

Objectives: miR-200c-3p has been shown to serve as a tumor suppressor in various tumor types. However, the biological function of miR-200c-3p in nephroblastoma remains unknown. This study aims to investigate the biological function and regulatory mechanisms of miR-200c-3p in nephroblastoma development. Methods: The expression of miR-200c-3p in nephroblastoma tissues and cells was evaluated by quantitative real-time polymerase chain reaction (qRT-PCR). The effects of miR-200c-3p on the proliferation and cell cycle of SK-NEP-1 nephroblastoma cell line were evaluated by CCK-8 assay, colony formation assay, and flow cytometry. The effects of miR-200c-3p on the migratory and invasive capacities of SK-NEP-1 cells were measured by wound healing assay and transwell assay. The ability of miR-200c-3p to target fibroblast growth factor receptor substrate 2 (FRS2) was detected by quantitative PCR, western blot, and luciferase reporter assay. Results: The expression of miR-200c-3p was significantly downregulated in nephroblastoma tissues and cells compared with that in normal renal tissues and cells. miR-200c-3p inhibited the proliferative, migratory, and invasive capacities of nephroblastoma cells by targeting FRS2. Conclusions: miR-200c-3p suppresses the malignant behaviors of nephroblastoma cells by downregulating the expression of FRS2.

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.