The let-7 microRNA represses cell proliferation pathways in human cells

MicroRNAs Targeting MYC Expression: Trace of Hope for Pancreatic Cancer Therapy. A Systematic Review

Background

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest malignancies and a major health problem worldwide. There were no major advances in conventional treatments in inhibiting tumor progression and increasing patient survival time. In order to suppress mechanisms responsible for tumor cell development such as those with oncogenic roles, more advanced therapeutic strategies should be sought. One of the most important oncogenes of pancreatic cancer is the MYC gene. The overexpression of MYC can activate many tumorigenic processes such as cell proliferation and pancreatic cancer cell invasion. MiRNAs are important molecules that are confirmed by targeting mRNA transcripts to regulate the expression of the MYC gene. Therefore, restoring MYC-repressing miRNAs expression tends to be an effective method of treating MYC-driven cancers.

Objective

The purpose of this study was to identify all validated microRNAs targeting C-MYC expression to inhibit PDAC progression by conducting a systematic review.

Methods

In this systematic review study, the papers published between 2000 and 2020 in major online scientific databases including PubMed, Scopus, and Web of Science were screened, following inclusion and exclusion criteria. We extracted all the experimental studies that showed miRNAs could target the expression of the MYC gene in PDAC.

Results

Eight papers were selected from a total of 89 papers. We found that six miRNAs (Let-7a, miR-145, miR-34a, miR-375, miR-494, and miR-148a) among the selected studies were validated for targeting MYC gene and three of them confirmed Let-7a as a direct MYC expression regulator in PC cells. Finally, we summarized the latest shreds of evidence of experimentally validated miRNAs targeting the MYC gene with respect to PDAC’s therapeutic potential.

Conclusion

Restoring the expression of MYC-repressing miRNAs tends to be an effective way to treat MYC-driven cancers such as PDAC. Several miRNAs have been proposed to target this oncogene via bioinformatics tools, but only a few have been experimentally validated for pancreatic cancer cells and models. Further studies should be conducted to find the interaction network of miRNA-MYC to develop more successful therapeutic strategies for PC, using the synergistic effects of these miRNAs.

Potential role of cyclin-dependent kinase 4/6 inhibitors in the treatment of squamous cell carcinoma of the head and neck

PURPOSE OF REVIEW

Human papillomavirus (HPV)-negative squamous cell carcinoma of the head and neck (SCCHN) is mainly driven by genetic aberrations involved in the cell cycle pathway resulting in cyclin-dependent kinase (CDK) 4 and 6 activation. This supports the investigation of the activity of CDK4/6 inhibitors in this disease. We review the therapeutic potential of CDK4/6 inhibitors in SCCHN.

RECENT FINDINGS

CDK4/6 inhibitors in monotherapy have demonstrated cytostatic activity in HPV-negative SCCHN. Combination with epidermal growth factor inhibitors, with phosphatidylinositol-3-kinase/protein kinase B/mammalian target of rapamycin pathways inhibitors or with immunotherapy, have shown promising preclinical efficacy. No strong predictive biomarkers of response or resistance have been firmly identified.Phase I clinical trials have demonstrated that palbociclib or ribociclib in combination with cetuximab is well tolerated. A phase II single-arm trial combining palbociclib/cetuximab has shown promising results.

SUMMARY

Inhibition of CDK4/6 represents a new potential treatment for HPV-negative SCCHN patients. Randomized clinical trials that investigate these compounds in an unbiased manner are needed to fully evaluate their efficacy. However, it is unlikely that all the patients will benefit from this new approach. To determine a molecular profile/phenotype that will predict CDK4/6 inhibitor activity, researchers will have to take into account simultaneously occurring events in the cyclin-D/CDK4/CDK6/retinoblastoma and associated pathways.

Epigenetic regulators of the revascularization response to chronic arterial occlusion

Peripheral arterial disease (PAD) is the leading cause of lower limb amputation and estimated to affect over 202 million people worldwide. PAD is caused by atherosclerotic lesions that occlude large arteries in the lower limbs, leading to insufficient blood perfusion of distal tissues. Given the severity of this clinical problem, there has been long-standing interest in both understanding how chronic arterial occlusions affect muscle tissue and vasculature and identifying therapeutic approaches capable of restoring tissue composition and vascular function to a healthy state. To date, the most widely utilized animal model for performing such studies has been the ischaemic mouse hindlimb. Despite not being a model of PAD per se, the ischaemic hindlimb model does recapitulate several key aspects of PAD. Further, it has served as a valuable platform upon which we have built much of our understanding of how chronic arterial occlusions affect muscle tissue composition, muscle regeneration and angiogenesis, and collateral arteriogenesis. Recently, there has been a global surge in research aimed at understanding how gene expression is regulated by epigenetic factors (i.e. non-coding RNAs, histone post-translational modifications, and DNA methylation). Thus, perhaps not unexpectedly, many recent studies have identified essential roles for epigenetic factors in regulating key responses to chronic arterial occlusion(s). In this review, we summarize the mechanisms of action of these epigenetic regulators and highlight several recent studies investigating the role of said regulators in the context of hindlimb ischaemia. In addition, we focus on how these recent advances in our understanding of the role of epigenetics in regulating responses to chronic arterial occlusion(s) can inform future therapeutic applications to promote revascularization and perfusion recovery in the setting of PAD.

Hydrophobically Modified let-7b miRNA Enhances Biodistribution to NSCLC and Downregulates HMGA2 In Vivo

MicroRNAs (miRNAs) have increasingly been shown to be involved in human cancer, and interest has grown about the potential use of miRNAs for cancer therapy. miRNA levels are known to be altered in cancer cells, including in non-small cell lung cancer (NSCLC), a subtype of lung cancer that is the most prevalent form of cancer worldwide and that lacks effective therapies. The let-7 miRNA is involved in the regulation of oncogene expression in cells and directly represses cancer growth in the lung. let-7 is therefore a potential molecular target for tumor therapy. However, applications of RNA interference for cancer research have been limited by a lack of simple and efficient methods to deliver oligonucleotides (ONs) to cancer cells. In this study, we have used in vitro and in vivo approaches to show that HCC827 cells internalize hydrophobically modified let-7b miRNAs (hmiRNAs) added directly to the culture medium without the need for lipid formulation. We identified functional let-7b hmiRNAs targeting the HMGA2 mRNA, one of the let-7 target genes upregulated in NSCLC, and show that direct uptake in HCC827 cells induced potent and specific gene silencing in vitro and in vivo. Thus, hmiRNAs constitute a novel class of ONs that enable functional studies of genes involved in cancer biology and are potentially therapeutic molecules.

Intercalating the Role of MicroRNAs in Cancer: As Enemy or Protector

Objective:

The transformation in cells at genetic levels stimulatesthe proliferation of cancer. The current review highlights the role of miRNA in management of cancer by altering processes of body at cellular levels.

Methods:

A deep research on the literature available till date for miRNA in cancer was conducted using various medical sites like PubMed, MEDLINE from internet and data was collected. The articles were majorly preferred in English language.

Results:

The development of normal cells into cancerous cells is a multivalent procedure highlighting numerous responsible factors. During the progression of cancer, the role of oncogene and tumor suppressor genes outshines at different levels of tumorogenesis. Metastasis poses highest threat in cancer progression and fabricates obstacles to clinicians and researchers in preventing formation of tumor on secondary sites. The mesenchymal-epithelial transition (MET) and epithelial mesenchymal transition (EMT) induce dissemination and ultimately progression of cancer.

Conclusion:

A comprehensive knowledge of the altered genes and the mechanism by which they induce formation of tumor is essential as they contribute in proliferating cancer at various stages, aggravating clinical symptoms. Hence miRNAs can be efficiently employed as an emerging treatment therapy for cancer.

Unraveling the Role of MicroRNAs in Mycobacterium tuberculosis Infection and Disease: Advances and Pitfalls

Tuberculosis (TB) is an infectious disease of extremely high epidemiological burden worldwide that is easily acquired through the inhalation of infected respiratory droplets. The complex pathogenesis of this infection spans from subjects never developing this disease despite intense exposure, to others in which immune containment fails catastrophically and severe or disseminated forms of disease ensue. In recent decades, microRNAs (miRNAs) have gained increasing attention due to their role as gene silencers and because of their altered expression in diverse human diseases, including some infections. Recent research regarding miRNAs and TB has revealed that the expression profile for particular miRNAs clearly changes upon Mycobacterium tuberculosis infection and also varies in the different stages of this disease. However, despite the growing number of studies-some of which have even proposed some miRNAs as potential biomarkers-methodological variations and key differences in relevant factors, such as sex and age, cell type analyzed, M. tuberculosis strain, and antimicrobial therapy status, strongly hinder the comparison of data. In this review, we summarize and discuss the literature and highlight the role of selected miRNAs that have specifically and more consistently been associated with M. tuberculosis infection, together with a discussion of the possible gene and immune regulation pathways involved.

miR-129-5p inhibits proliferation, migration, and invasion in rectal adenocarcinoma cells through targeting E2F7

microRNAs (miRNAs), a kind of small noncoding RNAs, are considered able to regulate expression of genes and mediate RNA silencing. miR-129-5p was shown to be a cancer-related miRNA. However, the influence of miR-129-5p in rectal adenocarcinoma (READ) development remains to be determined. Based on the TCGA data, downregulation of miR-129-5p in READ samples was observed. Manual restoration of the miR-129-5p in SW1463 and SW480 cell lines significantly inhibited invasion, migration, and proliferation of READ cell lines, while the apoptosis ability was enhanced. Meanwhile, we found E2F7 acted as a potential target of miR-129-5p and was upregulated in READ samples. E2F7 upregulation reversed the repression of miR-129-5p on READ development. Finally, in vivo experiments showed that inhibition of tumor growth in nude mice was achieved through upregulating miR-129-5p. Overall, our findings suggest increasing of miR-129-5p leads to the suppression of READ progression through regulating the expression of E2F7, which may provide novel insights into the treatment of READ.

Comprehensive circular RNA expression profiling with associated ceRNA network reveals their therapeutic potential in cholesteatoma

Cholesteatoma is a chronic disease that pathologically displays a benign tumor with excessive squamous epithelial cell proliferation in the middle ear. Clinically, however, it can manifest malignant behavior by destroying adjacent tissues and organs. Although previous studies have demonstrated that the pathogenesis of cholesteatoma is correlated with epigenetic dysregulation, the exact mechanism remains unclear. Circular RNAs (circRNAs) have been revealed as being abundantly expressed in various organisms and have been found to contribute to the regulation of many diseases. To date, no reports have elucidated their expression profiles and functions in cholesteatoma. In the present study, the circRNA expression profile in cholesteatoma was explored for the first time by using microarray analysis. We obtained a total of 355 significantly differentially expressed circRNAs in cholesteatoma, among which 101 were identified to be upregulated and 254 downregulated. By constructing circRNA‑lncRNA‑miRNA‑mRNA competing endogenous RNA (ceRNA) network, it was discovered that circRNAs may function as ceRNAs and contribute to the formation of cholesteatoma. These results provide novel insight into the pathogenesis of cholesteatoma and suggest circRNAs as potential promising therapeutic targets for cholesteatoma.

Differentiation of Pathogenic Th17 Cells Is Negatively Regulated by Let-7 MicroRNAs in a Mouse Model of Multiple Sclerosis

Multiple sclerosis (MS) is a disabling demyelinating autoimmune disorder of the central nervous system (CNS) which is driven by IL-23- and IL-1β-induced autoreactive Th17 cells that traffic to the CNS and secrete proinflammatory cytokines. Th17 pathogenicity in MS has been correlated with the dysregulation of microRNA (miRNA) expression, and specific miRNAs have been shown to promote the pathogenic Th17 phenotype. In the present study, we demonstrate, using the animal model of MS, experimental autoimmune encephalomyelitis (EAE), that let-7 miRNAs confer protection against EAE by negatively regulating the proliferation, differentiation and chemokine-mediated migration of pathogenic Th17 cells to the CNS. Specifically, we found that let-7 miRNAs may directly target the cytokine receptors Il1r1 and Il23r, as well as the chemokine receptors Ccr2 and Ccr5. Therefore, our results identify a novel regulatory role for let-7 miRNAs in pathogenic Th17 differentiation during EAE development, suggesting a promising therapeutic application for disease treatment.

U1 snRNP regulates cancer cell migration and invasion in vitro

Stimulated cells and cancer cells have widespread shortening of mRNA 3'-untranslated regions (3'UTRs) and switches to shorter mRNA isoforms due to usage of more proximal polyadenylation signals (PASs) in introns and last exons. U1 snRNP (U1), vertebrates' most abundant non-coding (spliceosomal) small nuclear RNA, silences proximal PASs and its inhibition with antisense morpholino oligonucleotides (U1 AMO) triggers widespread premature transcription termination and mRNA shortening. Here we show that low U1 AMO doses increase cancer cells' migration and invasion in vitro by up to 500%, whereas U1 over-expression has the opposite effect. In addition to 3'UTR length, numerous transcriptome changes that could contribute to this phenotype are observed, including alternative splicing, and mRNA expression levels of proto-oncogenes and tumor suppressors. These findings reveal an unexpected role for U1 homeostasis (available U1 relative to transcription) in oncogenic and activated cell states, and suggest U1 as a potential target for their modulation.

RNA-Based Therapeutics: From Antisense Oligonucleotides to miRNAs

The first therapeutic nucleic acid, a DNA oligonucleotide, was approved for clinical use in 1998. Twenty years later, in 2018, the first therapeutic RNA-based oligonucleotide was United States Food and Drug Administration (FDA) approved. This promises to be a rapidly expanding market, as many emerging biopharmaceutical companies are developing RNA interference (RNAi)-based, and RNA-based antisense oligonucleotide therapies. However, miRNA therapeutics are noticeably absent. miRNAs are regulatory RNAs that regulate gene expression. In disease states, the expression of many miRNAs is measurably altered. The potential of miRNAs as therapies and therapeutic targets has long been discussed and in the context of a wide variety of infections and diseases. Despite the great number of studies identifying miRNAs as potential therapeutic targets, only a handful of miRNA-targeting drugs (mimics or inhibitors) have entered clinical trials. In this review, we will discuss whether the investment in finding potential miRNA therapeutic targets has yielded feasible and practicable results, the benefits and obstacles of miRNAs as therapeutic targets, and the potential future of the field.

Cascade signal amplification sensing strategy for highly specific and sensitive detection of homologous microRNAs in different molecular subtypes of breast cancer

Discriminative identification of homologous miRNAs in miRNA family with high specificity and sensitivity is crucial for accurate classification, diagnosis and prognosis of breast cancer. Herein, we report a reliable, sensitive, and selective assay by coupling fluorescence resonance energy transfer (FRET) with cascade signal amplification. The strategy is developed by designing two programmable DNA probes that can be triggered to shift from "off" to "on" state in a cascade hybridization reaction in the presence of target miRNA let-7a, leading to the generation of an amplified signal. The assay can detect concentrations as low as ∼3.0 pM let-7a and discriminate let-7a from other highly homologous members in the let-7 miRNA family. Moreover, it can also be used to determine let-7a levels at single-cell resolution and evaluate the drug efficacy of let-7a expression among various molecular types of breast cancer cell lines. The advantage of this assay is a combined result of signal generation and amplification triggered by target miRNA, which can satisfy an assay of analogous miRNA in a downregulated manner with high specificity. It has promising potential as a selective assay for homologous miRNAs in precision medicine.

Sensitive Detection of Argonaute2 by Triple-Helix Molecular Switch Reaction and Pyrene Excimer Switching

RNA interference (RNAi) is a powerful tool for silencing target genes in a variety of cells and has great therapeutic potential. It is triggered by small interfering RNAs (siRNAs) and by an RNA-binding protein (argonaute, Ago). In this manuscript, we designed a simple fluorescence sensor strategy for sensitive detection of argonaute2 (Ago2) based on the base pairing principle of Watson–Crick and Hoogsteen and the pyrene excimer switch. The sensing platform has extremely high sensitivity and a detection limit of 0.1nM. It can be used to detect endogenous Ago2 in cancer cells and has great potential in clinical diagnosis and biomedical research.

Circulating MicroRNAs as Potential Biomarkers for Lung Cancer

Lung cancer is the number one cause of cancer-related mortality worldwide. To improve disease outcome, it is crucial to implement biomarkers into the clinics which assist physicians in their decisions regarding diagnosis, prognosis, as well as prediction of treatment response. Liquid biopsy offers an opportunity to obtain such biomarkers in a minimal invasive manner by retrieving tumor-derived material from body fluids of the patient. The abundance of circulating microRNAs is known to be altered in disease and has therefore been studied extensively as a cancer biomarker. Circulating microRNAs present a variety of favorable characteristics for application as liquid biopsy-based biomarkers, including their high stability, relatively high abundance, and presence is nearly all body fluids. Although the application of circulating microRNAs for the management of lung cancer has not entered the clinics yet, several studies showed their utility for diagnosis, prognosis, and efficacy prediction of various treatment strategies, including surgery, radio-/chemotherapy, as well as targeted therapy. To compensate for their limited tumor specificity, several microRNAs are frequently combined into microRNA panels. Moreover, the possibility to combine single microRNAs or microRNA panels with tumor imaging or other cancer-specific biomarkers has the potential to increase specificity and sensitivity and could lead to the clinical application of novel multi-marker combinations.

A versatile luminescent resonance energy transfer (LRET)-based ratiometric upconversion nanoprobe for intracellular miRNA biosensing

A versatile LRET-based ratiometric (LBRU) nanoprobe of NaYF₄:Yb,Er@NaYF₄@NH₂–mSiO₂/rhodamine B/C-DNA sandwich-structured nanocomposites has been developed for intracellular miRNA biosensing.

MicroRNA-129 Inhibits Glioma Cell Growth by Targeting CDK4, CDK6, and MDM2

Glioblastoma is the most common malignant primary brain tumor among adults and one of the most lethal cancers. It is characterized by the deregulation of signaling pathways involving proliferation, growth, survival, and other factors. MicroRNAs (miRNAs) play a role in the regulation of genes by affecting the 3′ untranslated region (UTR) of mRNA and affect many cell functions. The present study showed that miR-129 decreased the expression of retinoblastoma and p53 signaling pathways’ genes, including CDK4, CDK6, and MDM2. The real-time PCR data indicated that expression of CDK4 in U251 and U87 cell lines declined by 69.8% and 47% (p < 0.05), respectively, and expression of CDK6 and MDM2 in U251 cells decreased by 55.3% (p < 0.0001) and 34.7% (p < 0.05), respectively. Luciferase assays confirmed that overexpression of miR-129 decreased the expression of the CDK4 gene by 58.9% (p < 0.01), CDK6 by 35.7% (p < 0.0001), and MDM2 by 49% (p < 0.001). Moreover, cell cycle assays showed a decrease of the G₂-phase population to 10% and pre-G₂ arrest in U87 cells (p < 0.05). Additionally, wound healing assays indicated that miR-129 overexpression inhibits cell growth of glioblastoma cells. These findings introduced novel targets for miR-129 in glioblastoma cells.

Mesenchymal Stem Cell-Derived Exosomes and Other Extracellular Vesicles as New Remedies in the Therapy of Inflammatory Diseases

There is growing evidence that mesenchymal stem cell (MSC)-based immunosuppression was mainly attributed to the effects of MSC-derived extracellular vesicles (MSC-EVs). MSC-EVs are enriched with MSC-sourced bioactive molecules (messenger RNA (mRNA), microRNAs (miRNAs), cytokines, chemokines, immunomodulatory factors) that regulate phenotype, function and homing of immune cells. In this review article we emphasized current knowledge regarding molecular mechanisms responsible for the therapeutic effects of MSC-EVs in attenuation of autoimmune and inflammatory diseases. We described the disease-specific cellular targets of MSC-EVs and defined MSC-sourced molecules, which were responsible for MSC-EV-based immunosuppression. Results obtained in a large number of experimental studies revealed that both local and systemic administration of MSC-EVs efficiently suppressed detrimental immune response in inflamed tissues and promoted survival and regeneration of injured parenchymal cells. MSC-EVs-based anti-inflammatory effects were relied on the delivery of immunoregulatory miRNAs and immunomodulatory proteins in inflammatory immune cells (M1 macrophages, dendritic cells (DCs), CD4+Th1 and Th17 cells), enabling their phenotypic conversion into immunosuppressive M2 macrophages, tolerogenic DCs and T regulatory cells. Additionally, through the delivery of mRNAs and miRNAs, MSC-EVs activated autophagy and/or inhibited apoptosis, necrosis and oxidative stress in injured hepatocytes, neurons, retinal cells, lung, gut and renal epithelial cells, promoting their survival and regeneration.

Mechanistic Understanding of Curcumin's Therapeutic Effects in Lung Cancer

Lung cancer is among the most common cancers with a high mortality rate worldwide. Despite the significant advances in diagnostic and therapeutic approaches, lung cancer prognoses and survival rates remain poor due to late diagnosis, drug resistance, and adverse effects. Therefore, new intervention therapies, such as the use of natural compounds with decreased toxicities, have been considered in lung cancer therapy. Curcumin, a natural occurring polyphenol derived from turmeric (Curcuma longa) has been studied extensively in recent years for its therapeutic effects. It has been shown that curcumin demonstrates anti-cancer effects in lung cancer through various mechanisms, including inhibition of cell proliferation, invasion, and metastasis, induction of apoptosis, epigenetic alterations, and regulation of microRNA expression. Several in vitro and in vivo studies have shown that these mechanisms are modulated by multiple molecular targets such as STAT3, EGFR, FOXO3a, TGF-β, eIF2α, COX-2, Bcl-2, PI3KAkt/mTOR, ROS, Fas/FasL, Cdc42, E-cadherin, MMPs, and adiponectin. In addition, limitations, strategies to overcome curcumin bioavailability, and potential side effects as well as clinical trials were also reviewed.

Identification of potential molecular pathogenesis mechanisms modulated by microRNAs in patients with Intestinal Neuronal Dysplasia type B

This study proposed to determine global microRNA (miRNA) expression and miRNA-regulated pathways in Intestinal Neuronal Dysplasia type B (IND-B). Fifty patients (0-15 years old) with IND-B were included in the study. Peripheral blood samples were collected from all 50 patients and from 10 healthy asymptomatic children (controls). Rectal biopsies were collected from 29/50 patients; biopsy tissues were needle microdissected to isolate the different intestinal layers, for molecular analysis. Global miRNA expression was determined using TaqMan arrays. Correlation analysis between miRNA expression in plasma and biopsy samples as well as among tissues derived from the distinct intestinal layers was performed. Computational approaches were used for miRNA target prediction/identification of miRNA-regulated genes and enriched pathways biologically relevant to IND-B pathogenesis. miRNAs were statistically significantly deregulated (FC ≥ 2 and p ≤ 0.05) in submucosal and muscular layers: over-expressed (miR-146a and miR-146b) and under-expressed (miR-99a, miR-100, miR-130a, miR-133b, miR-145, miR-365, miR-374-5p, miR-451). Notably, let-7a-5p was highly over-expressed in patient plasma compared to healthy controls (FC = 17.4). In addition, miR-451 was significantly under-expressed in both plasma and all biopsy tissues from the same patients. Enriched pathways (p < 0.01) were axon guidance, nerve growth factor signalling, NCAM signalling for neurite out-growth, neuronal system and apoptosis. miRNA expression is deregulated in the submucosa and muscular layers of the rectum and detected in plasma from patients with IND-B. Biologically enriched pathways regulated by the identified miRNAs may play a role in IND-B disease pathogenesis, due to the activity related to the neurons of the enteric nervous system.

Let-7 miRNA's Expression Profile and Its Potential Prognostic Role in Uterine Leiomyosarcoma

The lethal-7 (let-7) family is an important microRNA (miRNA) group that usually exerts functions as a tumor suppressor. We aimed to evaluate the expression profile of let-7a, let-7b, let-7c, let-7d, let-7e, let-7f, let-7g, and let-7i and to assess their value as prognostic markers in uterine leiomyosarcoma (LMS) patients. The miRNAs expression profile was assessed in 34 LMS and 13 normal myometrium (MM) paraffin-embedded samples. All let-7 family members showed downregulation in LMS. Our findings showed that patients with let-7e downregulation had worse overall survival (OS) and is an independent prognostic factor (hazard ratio [HR] = 2.24). In addition, almost half the patients had distant metastasis. LMS patients with downregulated let-7b and let-7d had worse disease-free survival (DFS); they are not independent prognostic factors (HR = 2.65). Patients’ ages were associated with let-7d, let-7e and let-7f (p = 0.0160) downregulation. In conclusion, all the let-7 family members were downregulated in LMS patients, and the greater the loss of expression of these molecules, the greater their relationship with worse prognosis of patients. Let-7e expression might influence the OS, while let-7b and le-7d might influence the DFS. The lowest expression levels of let-7d, let-7e, and let-7f were associated with the oldest patients. Our findings indicate strong evidence of let-7’s role as a potential prognostic biomarker in LMS.

Therapeutic Inducers of Apoptosis in Ovarian Cancer

Ovarian cancers remain one of the most common causes of gynecologic cancer-related death in women worldwide. The standard treatment comprises platinum-based chemotherapy, and most tumors develop resistance to therapeutic drugs. One mechanism of developing drug resistance is alterations of molecules involved in apoptosis, ultimately assisting in the cells' capability to evade death. Thus, there is a need to focus on identifying potential drugs that restore apoptosis in cancer cells. Here, we discuss the major inducers of apoptosis mediated through various mechanisms and their usefulness as potential future treatment options for ovarian cancer. Broadly, they can target the apoptotic pathways directly or affect apoptosis indirectly through major cancer-pathways in cells. The direct apoptotic targets include the Bcl-2 family of proteins and the inhibitor of apoptotic proteins (IAPs). However, indirect targets include processes related to homologous recombination DNA repair, micro-RNA, and p53 mutation. Besides, apoptosis inducers may also disturb major pathways converging into apoptotic signals including janus kinase (JAK)/signal transducer and activator of transcription 3 (STAT3), wingless-related integration site (Wnt)/β-Catenin, mesenchymal-epithelial transition factor (MET)/hepatocyte growth factor (HGF), mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK), and phosphatidylinositol 3-kinase (PI3K)/v-AKT murine thymoma viral oncogene homologue (AKT)/mammalian target of rapamycin (mTOR) pathways. Several drugs in our review are undergoing clinical trials, for example, birinapant, DEBIO-1143, Alisertib, and other small molecules are in preclinical investigations showing promising results in combination with chemotherapy. Molecules that exhibit better efficacy in the treatment of chemo-resistant cancer cells are of interest but require more extensive preclinical and clinical evaluation.

IL-27 receptor-regulated stress myelopoiesis drives abdominal aortic aneurysm development

Abdominal aortic aneurysm (AAA) is a prevalent life-threatening disease, where aortic wall degradation is mediated by accumulated immune cells. Although cytokines regulate inflammation within the aorta, their contribution to AAA via distant alterations, particularly in the control of hematopoietic stem cell (HSC) differentiation, remains poorly defined. Here we report a pathogenic role for the interleukin-27 receptor (IL-27R) in AAA, as genetic ablation of IL-27R protects mice from the disease development. Mitigation of AAA is associated with a blunted accumulation of myeloid cells in the aorta due to the attenuation of Angiotensin II (Ang II)-induced HSC expansion. IL-27R signaling is required to induce transcriptional programming to overcome HSC quiescence and increase differentiation and output of mature myeloid cells in response to stress stimuli to promote their accumulation in the diseased aorta. Overall, our studies illuminate how a prominent vascular disease can be distantly driven by a cytokine-dependent regulation of bone marrow precursors.

Let-7 regulates cell cycle dynamics in the developing cerebral cortex and retina

In the neural progenitors of the developing central nervous system (CNS), cell proliferation is tightly controlled and coordinated with cell fate decisions. Progenitors divide rapidly during early development and their cell cycle lengthens progressively as development advances to eventually give rise to a tissue of the correct size and cellular composition. However, our understanding of the molecules linking cell cycle progression to developmental time is incomplete. Here, we show that the microRNA (miRNA) let-7 accumulates in neural progenitors over time throughout the developing CNS. Intriguingly, we find that the level and activity of let-7 oscillate as neural progenitors progress through the cell cycle by in situ hybridization and fluorescent miRNA sensor analyses. We also show that let-7 mediates cell cycle dynamics: increasing the level of let-7 promotes cell cycle exit and lengthens the S/G2 phase of the cell cycle, while let-7 knock down shortens the cell cycle in neural progenitors. Together, our findings suggest that let-7 may link cell proliferation to developmental time and regulate the progressive cell cycle lengthening that occurs during development.

Exploring the Potential of MicroRNA Let-7c as a Therapeutic for Prostate Cancer

Prostate cancer (PCa) is one of the leading causes of mortality worldwide and often presents with aberrant microRNA (miRNA) expression. Identifying and understanding the unique expression profiles could aid in the detection and treatment of this disease. This review aims to identify miRNAs as potential therapeutic targets for PCa. Three bio-informatic searches were conducted to identify miRNAs that are reportedly implicated in the pathogenesis of PCa. Only hsa-Lethal-7 (let-7c), recognized for its role in PCa pathogenesis, was common to all three databases. Three further database searches were conducted to identify known targets of hsa-let-7c. Four targets were identified, HMGA2, c-Myc (MYC), TRAIL, and CASP3. An extensive review of the literature was undertaken to assess the role of hsa-let-7c in the progression of other malignancies and to evaluate its potential as a therapeutic target for PCa. The heterogeneous nature of cancer makes it logical to develop mechanisms by which the treatment of malignancies is tailored to an individual, harnessing specific knowledge of the underlying biology of the disease. Resetting cellular miRNA levels is an exciting prospect that will allow this ambition to be realized.

CSB affected on the sensitivity of lung cancer cells to platinum-based drugs through the global decrease of let-7 and miR-29

Background

Transcription-coupled nucleotide excision repair (TC-NER) plays a prominent role in the removal of DNA adducts induced by platinum-based chemotherapy reagents. Cockayne syndrome protein B (CSB), the master sensor of TCR, is also involved in the platinum resistant. Let-7 and miR-29 binding sites are highly conserved in the proximal 3′UTR of CSB.

Methods

We conducted immunohistochemisty to examine the expression of CSB in NSCLC. To determine whether let-7 family and miR-29 family directly interact with the putative target sites in the 3′UTR of CSB, we used luciferase reporter gene analysis. To detect the sensitivity of non-small cell lung cancer (NSCLC) cells to platinum-based drugs, CCK analysis and apoptosis analysis were performed.

Results

We found that let-7 and miR-29 negatively regulate the expression of CSB by directly targeting to the 3′UTR of CSB. The endogenous CSB expression could be suppressed by let-7 and miR-29 in lung cancer cells. The suppression of CSB activity by endogenous let-7 and miR-29 can be robustly reversed by their sponges. Down-regulation of CSB induced apoptosis and increased the sensitivity of NSCLC cells to cisplatin and carboplatin drugs. Let-7 and miR-29 directly effect on cisplatin and carboplatin sensitivity in NSCLC.

Conclusions

In conclusion, the platinum-based drug resistant of lung cancer cells may involve in the regulation of let-7 and miR-29 to CSB.

MicroRNA‑4500 suppresses tumor progression in non‑small cell lung cancer by regulating STAT3

Research has revealed that microRNA (miR)-4500 is downregulated in non-small cell lung cancer (NSCLC), and miR-4500 suppresses tumor growth by targeting lin-28 homolog B and NRAS proto-oncogene, GTPase. In the present study, it was reported that signal transducer and activator of transcription 3 (STAT3) may function as a novel target gene for miR-4500 in NSCLC. The experiments conducted in the present study confirmed that the miR-4500 expression was decreased in NSCLC tissues and cells compared with adjacent normal tissues and a normal lung cell line. miR-4500 suppressed the cell proliferation, migration, invasion and promoted apoptosis of the human NSCLC cell lines A549 and H1975. Expression of STAT3 was negatively correlated with miR-4500 expression in vivo. A luciferase reporter assay suggested that miR-4500 directly targeted the 3′ untranslated region of STAT3. The tumor inhibition effect of small interfering RNA STAT3 in A549 and H1975 lines may be partially impaired by a miR-4500 inhibitor. The results of the present study suggests that miR-4500 may be a tumor suppressor and a potential therapeutic target in NSCLC.

A label-free aptamer-based biosensor for microRNA detection by the RNA-regulated fluorescence of malachite green

MicroRNAs (miRNAs) have been considered as promising molecular biomarkers for disease diagnosis, prognosis, as well as drug development. Herein, we wish to report a low background and label-free aptamer-based biosensor for miRNA assay by RNA-regulated fluorescence of malachite green (MG). In this biosensor-based strategy, target miRNA can specifically hybridize with the DNA extension template to form the T7 in vitro transcription system. Then the following transcription amplification produces a large number of MG RNA aptamers (MGAs) which light up the fluorescence of the MG, achieving significant fluorescence enhancement for miRNA quantitative analysis. The aptamer-based biosensor exhibits high sensitivity with a quite low detection limit of 10 amol target miRNA and high specificity to clearly discriminate very similar miRNA family members, even only one base difference. Furthermore, we have demonstrated that the biosensor is practical and reliable for the quantitative detection of miRNA in complex real samples.

Inhibition of breast cancer cell proliferation with anti-microRNA oligonucleotides flanked by interstrand cross-linked duplexes

Breast cancer is the most frequent cancer affecting women worldwide. Traditional chemotherapy, hormone therapy, and targeted therapy are used for breast cancer treatment. However, breast cancer is a heterogeneous disease, and patients often develop drug resistance. Therefore, various new therapeutic strategies have been investigated, including microRNA regulation. Anti-microRNA oligonucleotides (AMOs) are one of the most potent agents in oligonucleotide therapy. The inhibition activity of an AMO can be increased by flanking its single-stranded antisense sequence (the widely used structure for AMOs) with interstrand cross-linked duplexes (CLDs). An extrastable CLD improves nuclease resistance and stabilizes hybridization with a target. This study investigated the effects of anti-microRNA-21 (miR-21) AMO modified with CLDs on breast cancer cells without using reporter assay. The CLD-modified AMO suppressed breast cancer cell proliferation for a long duration compared to other types of AMOs. In addition, it expectedly up-regulated the miR-21-controlled expression of tumor suppressor genes. Therefore, an AMO flanked by CLDs can be a promising strategy for breast cancer treatment.

HDAC6 Suppresses Let-7i-5p to Elicit TSP1/CD47-Mediated Anti-Tumorigenesis and Phagocytosis of Hepatocellular Carcinoma

Histone deacetylase 6 (HDAC6) uniquely serves as a tumor suppressor in hepatocellular carcinogenesis, but the underlying mechanisms leading to tumor suppression are not fully understood. To identify comprehensive microRNAs (miRNAs) regulated by HDAC6 in hepatocellular carcinogenesis, differential miRNA expression analysis of HDAC6-transfected Hep3B cells was performed. Using integrative analyses of publicly available transcriptome data and miRNA target prediction, we selected five candidate miRNAs and, through in vitro functional validation, showed that let-7i-5p specifically suppressed thrombospondin-1 (TSP1) in hepatocellular carcinoma (HCC). Ectopic expression of antisense let-7i-5p (AS-let-7i-5p) inhibited in vitro tumorigenesis of HCC cells. In addition, treatments of partially purified TSP1 from culture cell media (ppTSP1) and recombinant TSP1 (rTSP1) exhibited similar effects with AS-let-7i-5p treatment on the same HCC cells, whereas TSP1 neutralizing antibody treatment significantly attenuated these effects. Notably, treatments of HDAC6 plasmid, AS-let-7i-5p, ppTSP1, and rTSP1 significantly suppressed in vitro angiogenesis and metastatic potential of HCC cells, but the co-treatment of TSP1 antibody specific to cluster of differentiation 47 (CD47) binding domain successfully blocked these effects in the same cells. Furthermore, we demonstrated that recovery of HDAC6 elicited let-7i-5p suppression to de-repress TSP1 expression; therefore, it occupied the CD47 receptor to block CD47-SIRPα-mediated anti-phagocytosis of macrophage in HCC. We also observed that HCC-derived exosomal let-7i-5p suppressed TSP1 of recipient hepatocyte cells. Treatments of HDAC6 plasmid, AS-let-7i-5p, and rTSP1 suppressed tumor incidence as well as tumor growth rates in a spontaneous mouse HCC model. Conclusion: Our findings suggest that the HDAC6-let-7i-5p-TSP1 regulatory pathway suppresses neoplastic and antiphagocytic behaviors of HCC by interacting with cell surface receptor CD47 in HCC and neighboring cells of tumor microenvironment, providing a therapeutic target for the treatment of liver malignancy and metastasis.

A five-miRNA panel in plasma was identified for breast cancer diagnosis

Breast cancer (BC) is one of the most common cancers in females. Since early detection can bring prognosis benefit, discovery of novel noninvasive biomarkers for BC diagnosis is in urgent need. In this four‐phase study, we profiled miRNA expression in plasma samples from a total of 257 BC patients and 257 normal controls (NCs). Exiqon miRNA qPCR panel was used to select candidate miRNAs in the screening phase which were further analyzed using qRT‐PCR in the following training, testing and external validation phases. Finally, we identified five plasma miRNAs (let‐7b‐5p, miR‐122‐5p, miR‐146b‐5p, miR‐210‐3p and miR‐215‐5p) whose expression levels were significantly different between BC patients and NCs. A 5‐miRNA panel in plasma with high sensitivity and specificity was then constructed to detect BC. The areas under the receiver‐operating characteristic curves (AUCs) of the panel were 0.683, 0.966, 0.978 for the training, testing and external validation sets, respectively. Expression of the identified miRNAs was further analyzed among 32 pairs of BC tissue and the adjacent normal tissue samples as well as plasma‐derived exosome samples from 32 BC patients vs 32 NCs. Let‐7b‐5p was contrarily down‐regulated in BC tissue. In exosomes samples, only miR‐122‐5p was significantly up‐regulated as in plasma for BC patients. In conclusion, we identified a 5‐miRNA plasma panel (let‐7b‐5p, miR‐122‐5p, miR‐146b‐5p, miR‐210‐3p and miR‐215‐5p) that could serve as a promising biomarker for BC detection.

The Importance of microRNAs in RAS Oncogenic Activation in Human Cancer

microRNAs (miRNAs) regulate gene expression by modulating the translation of protein-coding RNAs. Their aberrant expression is involved in various human diseases, including cancer. Here, we summarize the experimental pieces of evidence that proved how dysregulated miRNA expression can lead to RAS (HRAS, KRAS, or NRAS) activation irrespective of their oncogenic mutations. These findings revealed relevant pathogenic mechanisms as well as mechanisms of resistance to target therapies. Based on this knowledge, potential approaches for the control of RAS oncogenic activation can be envisioned.

miR-9: From function to therapeutic potential in cancer

Malignant neoplasms are regarded as the main cause of death around the world; hence, many research studies were conducted to further perceive molecular mechanisms, treatment, and cancer prognosis. Cancer is known as a major factor for health-related problems in the world. The main challenges associated with these diseases are prompt diagnosis, disease remission classification and treatment status forecast. Therefore, progressing in such areas by developing new and optimized methods with the help of minimally invasive biological markers such as circular microRNAs (miRNAs) can be considered important. miRNA interactions with target genes have specified their role in development, apoptosis, differentiation, and proliferation and also, confirm direct miRNA function in cancer. Different miRNAs expression levels in various types of malignant neoplasms have been observed to be associated with prognosis of various carcinomas. miR-9 seems to implement opposite practices in different tissues or under various cancer incidences by influencing different genes. Aberrant miR-9 levels have been observed in many cancer types. Therefore, we intended to investigate the precise role of miR-9 in patients with malignant neoplasms. To this end, in this study, we attempted to examine different studies to clarify the overall role of miR-9 as a prognostic marker in several human tumors. The presented data in this study can help us to find the novel therapeutic avenues for treatment of human cancers.

Cisplatin decreases cyclin D2 expression via upregulating miR‑93 to inhibit lung adenocarcinoma cell growth

MicroRNAs (miRNAs/miRs) serve important roles in the chemotherapeutic effect of anticancer drugs. To investigate the roles of miRNAs in cisplatin‑induced suppression of lung adenocarcinoma cell proliferation, A549 cells were treated with different concentrations of cisplatin. An MTT assay demonstrated that cisplatin inhibited A549 cell proliferation in a dose‑dependent manner. Cisplatin induced cell apoptosis and inhibited cell migration by increasing the levels of miR‑93, miR‑26a and miR‑26b. Furthermore, as an upstream factor, miR‑93 was proposed to regulate cyclin D2 expression in miR‑93‑transfected A549 cells. Cisplatin also induced Bcl‑2‑associated X protein expression, and decreased that of Bcl‑2 and c‑Myc in lung adenocarcinoma cells. In vivo analysis further supported that cisplatin inhibited lung adenocarcinoma cell growth by regulating cyclin D2 and miR‑93 expression. In conclusion, our findings demonstrated that cisplatin could effectively inhibit lung adenocarcinoma cell proliferation by decreasing cyclin D2 expression via miR‑93.

Cancer-associated mutations in DICER1 RNase IIIa and IIIb domains exert similar effects on miRNA biogenesis

Somatic mutations in the RNase IIIb domain of DICER1 arise in cancer and disrupt the cleavage of 5' pre-miRNA arms. Here, we characterize an unstudied, recurrent, mutation (S1344L) in the DICER1 RNase IIIa domain in tumors from The Cancer Genome Atlas (TCGA) project and MSK-IMPACT profiling. RNase IIIa/b hotspots are absent from most cancers, but are notably enriched in uterine cancers. Systematic analysis of TCGA small RNA datasets show that DICER1 RNase IIIa-S1344L tumors deplete 5p-miRNAs, analogous to RNase IIIb hotspot samples. Structural and evolutionary coupling analyses reveal constrained proximity of RNase IIIa-S1344 to the RNase IIIb catalytic site, rationalizing why mutation of this site phenocopies known hotspot alterations. Finally, examination of DICER1 hotspot endometrial tumors reveals derepression of specific miRNA target signatures. In summary, comprehensive analyses of DICER1 somatic mutations and small RNA data reveal a mechanistic aspect of pre-miRNA processing that manifests in specific cancer settings.

Upregulated microRNA‑671‑3p promotes tumor progression by suppressing forkhead box P2 expression in non‑small‑cell lung cancer

In the present study, the expression of microRNA (miR)‑671‑3p in non‑small‑cell lung cancer (NSCLC) was detected via reverse transcription‑quantitative polymerase chain reaction analysis, and its role in cell proliferation, apoptosis, migration and invasion was investigated via Cell Counting Kit‑8, colony formation, flow cytometry, Transwell and scratch assays, respectively. It was observed that the expression of miR‑671‑3p was upregulated in NSCLC tissues and cell lines (A549 and H1975). Treatment with miR‑671‑3p inhibitors suppressed cell proliferation, migration and invasion, and increased apoptosis in vitro, suggesting that miR‑671‑3p functions as an oncogene in NSCLC. In addition, forkhead box P2 (FOXP2) has been reported to be a tumor suppressor that is downregulated in several types of cancer, and its low expression was confirmed in NSCLC tissues and cell lines in the current study via western blotting. The results of the luciferase reporter assay also demonstrated that miR‑671‑3p targeted directly the 3'‑untranslated region of FOXP2. Furthermore, overexpression of FOXP2 in A549 and H1975 cell lines suppressed the growth, migration and invasion, and promoted apoptosis, whereas these effects were reversed by transfection with miR‑671‑3p mimics, suggesting that miR‑671‑3p promoted tumor progression via regulating FOXP2. Taken together, the results reported in the present study implied that miR‑671‑3p may be a potential therapeutic target in NSCLC.

Differential expression of circRNAs during rat lung development

At present, thousands of circular RNAs (circRNAs) have been found in cancer and various tissues from different species. However, the expression of circRNAs during rat lung development remains largely unknown. In the present study, circRNA expression profiles were screened in three mixed rat lung tissues at 3 time-points [embryonic day (E) 19, E21 and post-natal (P) day 3] during fetal rat development with circRNA high-throughput sequencing. Preliminary results were verified by reverse transcription-PCR (RT-PCR) at 4 time-points (E16, E19, E21 and P3). A total of 375 circRNAs were differently expressed in E19 vs. E21 (fold change ≥1.5; P<0.05). At the same time, a total of 358 circRNAs were differently expressed in E21 vs. P3 (fold change ≥1.5; P<0.05). A total of 3 circRNAs (rno_circ:chr7:24777879-24784993, r n o _c i r c:c h r14:14 62 0 910 −14 62 49 33 a n d r n o _circ:chr3:1988750- 1998592) were characterized by having consistent fold changes (≥1.5) between 3 time-points (E19, E21 and P3) and were selected for RT-PCR at 4 time-points (E16, E19, E21 and P3). Subsequently, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis of parent genes of the differentially expressed circRNAs revealed that these circRNAs may serve important roles in lung development. The present results support that these new found circRNAs participate in lung development. Furthermore, these findings may help to clarify the physiopathological mechanism of normal rat lung development, and may further provide a physiopatho-logical basis of lung developmental diseases.

Coreactant-Free Dual Amplified Electrochemiluminescent Biosensor Based on Conjugated Polymer Dots for the Ultrasensitive Detection of MicroRNA

Generally, electrochemiluminescence (ECL) assays are performed in the presence of a coreactant. The addition of the coreactant in the detection solution would make the ECL system lack sufficient stability. In the case of dissolved oxygen as the coreactant, the unknown concentration of dissolved O₂ would result in an inevitable error and a lack of reproducibility in detection. A coreactant-free ECL assay could overcome the above shortcomings and thus is an ideal choice. In this work, a coreactant-free dual amplified ECL strategy was constructed for ultrasensitive detection of microRNA (miRNA). Here, target-catalyzed hairpin assembly and enzyme-triggered DNA walker recycling amplification were integrated to achieve dual signal amplification. Carboxyl-functionalized poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1'-3}-thiadiazole)] (PFBT-COOH) dots were used as luminophores, which displayed prominent ECL performance without adding any coreactants and removing the dissolved O₂. As a result, the detection of miRNA was achieved, and the linear range was from 10 aM to 5 pM, and the detection limit was low to 3.3 aM. Meanwhile, the practicability of our biosensor was investigated by analyzing the expression of miRNA in cell lysates. The PFBT-COOH dots provided a great platform for constructing coreactant-free ECL biosensors and expanded the application of conjugated polymer dots in clinical analysis.

Modeling the Dynamics of Let-7-Coupled Gene Regulatory Networks Linking Cell Proliferation to Malignant Transformation

Let-7 microRNA controls the expression of proteins that belong to two distinct gene regulatory networks, namely, a cyclin-dependent kinase (Cdk) network driving the cell cycle and a cell transformation network that can undergo an epigenetic switch between a non-transformed and a malignant transformed cell state. Using mathematical modeling and transcriptomic data analysis, we here investigate how Let-7 controls the Cdk-dependent cell cycle network, and how it couples the latter with the transformation network. We also assess the consequence of this coupling on cancer progression. Our analysis shows that the switch from a quiescent to a proliferative state depends on the relative levels of Let-7 and several cell cycle activators. Numerical simulations further indicate that the Let-7-coupled cell cycle and transformation networks mutually control each other, and our model identifies key players for this mutual control. Transcriptomic data analysis from The Cancer Genome Atlas (TCGA) suggests that the two networks are activated in cancer, in particular in gastrointestinal cancers, and that the activation levels vary significantly among patients affected by a same cancer type. Our mathematical model, when applied to a heterogeneous cell population, suggests that heterogeneity among tumors may in part result from stochastic switches between a non-transformed cell state with low proliferative capability and a transformed cell state with high proliferative property. The model further predicts that Let-7 may reduce tumor heterogeneity by decreasing the occurrence of stochastic switches toward a transformed, proliferative cell state. In conclusion, we identified the key components responsible for the qualitative dynamics of two networks interconnected by Let-7. The two networks are heterogeneously activated in several cancers, thereby stressing the need to consider patient’s specific characteristics to optimize therapeutic strategies.

MiR-195-5p Promotes Cardiomyocyte Hypertrophy by Targeting MFN2 and FBXW7

Cardiac hypertrophy mainly predicts heart failure and is highly linked with sudden loss of lives. MicroRNAs (miRNAs) play essential roles in the development of cardiac hypertrophy through binding to corresponding mRNA targets. In this study, in order to investigate the roles of two mature forms of miRNA-195, miR-195-3p, and miR-195-5p, in vitro and in vivo models of cardiac hypertrophy were established by applying angiotensin II (Ang II) to H9c2 cardiomyocytes and infusing chronic Ang II to mice, respectively. We found that miR-195-5p was evidently equally upregulated in the in vitro and in vivo studies of cardiac hypertrophy induced by Ang II. High expressed miR-195-5p could adequately promote hypertrophy, whereas the suppression of miR-195-5p prevented hypertrophy of H9c2 cardiomyocytes under Ang II treatment. Furthermore, the luciferase reporter system demonstrated that MFN2 and FBWX7 were target genes of miR-195-5p, which negatively regulated the expression of these two genes in H9c2 cells. By contrast, in both models, expression of miR-195-3p was only slightly changed without statistical significance. In addition, we observed a trend towards decreased expression of hypertrophic markers by overexpressing miR-195-3p in AngII-treated H9c2 cardiomyocytes in vitro. Taken together, our study indicates that miR-195-5p promotes cardiac hypertrophy via targeting MFN2 and FBXW7 and may provide promising therapeutic strategies for interfering cardiac hypertrophy.

Identification and Characterization of microRNAs and Their Predicted Functions in Biomineralization in the Pearl Oyster (Pinctada fucata)

The biological process of pearl formation is an ongoing research topic, and a number of genes associated with this process have been identified. However, the involvement of microRNAs (miRNAs) in biomineralization in the pearl oyster, Pinctada fucata, is not well understood. In order to investigate the divergence and function of miRNAs in P. fucata, we performed a transcriptome analysis of small RNA libraries prepared from adductor muscle, gill, ovary, and mantle tissues. We identified 186 known and 42 novel miRNAs in these tissues. Clustering analysis showed that the expression patterns of miRNAs were similar among the somatic tissues, but they differed significantly between the somatic and ovary tissues. To validate the existence of the identified miRNAs, nine known and three novel miRNAs were verified by stem-loop qRT-PCR using U6 snRNA as an internal reference. The expression abundance and target prediction between miRNAs and biomineralization-related genes indicated that miR-1990c-3p, miR-876, miR-9a-3p, and novel-3 may be key factors in the regulatory network that act by controlling the formation of matrix proteins or the differentiation of mineralogenic cells during shell formation in mantle tissue. Our findings serve to further clarify the processes underlying biomineralization in P. fucata.

LINC00261 suppresses human colon cancer progression via sponging miR-324-3p and inactivating the Wnt/β-catenin pathway

Growing evidence indicates long noncoding RNAs (lncRNAs) are significant regulators in the progression of various malignant tumors including colon cancer. Dysregulation of lncRNA LINC00261 has been identified in many cancers. Investigations on LINC00261 function have revealed that LINC00261 could act as a crucial tumor suppressor in various cancers. But, the biological involvement of LINC00261 in colon cancer is still barely known. Here, we found LINC00261 was reduced in colon cancer cells. Meanwhile, overexpressed LINC00261 repressed colon cancer cell viability and proliferation capacity. In addition, colony cancer cell colony formation was inhibited and apoptosis was enhanced by upregulation of LINC00261. Also, colon cancer cell migration and invasion both were restrained by LINC00261. miR-324-3p can exert important functions in several carcinomas, but its role in colon cancer is uninvestigated. In the current study, miR-324-3p was examined and miR-324-3p was greatly increased in colon cancer cells. Moreover, the association between miR-324-3p and LINC00261 was confirmed via performing RNA immunoprecipitation and RNA-pull-down experiments. In cancer biology, aberrant modulation of the Wnt signaling pathway remains a prevalent theme. Overexpression of LINC00261 obviously impaired colon cancer progression via inactivating the Wnt pathway. Furthermore, in the xenograft model assay, an increase of LINC00261 could suppress colon tumor growth via sponging miR-324-3p and inactivating the Wnt pathway. Overall, our results showed that LINC00261 repressed colon cancer progression via regulating miR-324-3p and the Wnt pathway. LINC00261 could be established as a novel therapeutic target for colon cancer.

Somatic Mutations in miRNA Genes in Lung Cancer-Potential Functional Consequences of Non-Coding Sequence Variants

A growing body of evidence indicates that miRNAs may either drive or suppress oncogenesis. However, little is known about somatic mutations in miRNA genes. To determine the frequency and potential consequences of miRNA gene mutations, we analyzed whole exome sequencing datasets of 569 lung adenocarcinoma (LUAD) and 597 lung squamous cell carcinoma (LUSC) samples generated in The Cancer Genome Atlas (TCGA) project. Altogether, we identified 1091 somatic sequence variants affecting 522 different miRNA genes and showed that half of all cancers had at least one such somatic variant/mutation. These sequence variants occurred in most crucial parts of miRNA precursors, including mature miRNA and seed sequences. Due to our findings, we hypothesize that seed mutations may affect miRNA:target interactions, drastically changing the pool of predicted targets. Mutations may also affect miRNA biogenesis by changing the structure of miRNA precursors, DROSHA and DICER cleavage sites, and regulatory sequence/structure motifs. We identified 10 significantly overmutated hotspot miRNA genes, including the miR-379 gene in LUAD enriched in mutations in the mature miRNA and regulatory sequences. The occurrence of mutations in the hotspot miRNA genes was also shown experimentally. We present a comprehensive analysis of somatic variants in miRNA genes and show that some of these genes are mutational hotspots, suggesting their potential role in cancer.

In silico prediction of MicroRNA role in regulation of Zebrafish (Danio rerio) responses to nanoparticle exposure

The release of nanoparticles to the environment can affect health of the exposed organisms. MicroRNAs have been suggested as potential toxicology biomarkers, however the information about use of microRNA in aquatic organisms exposed to nanoparticles (NP) is limited. In silico analysis from publicly available gene expression data was performed. Data selection for the analysis was based on reported biological and pathological outcomes of NP induced toxicity in zebrafish. After identifying relevant genes, we constructed six miRNA-mRNA regulatory networks involved in nanoparticle induced toxicological responses in zebrafish. Based on our prediction and selection criteria we selected six miRNAs that overlapped in constructed networks with remarkable prediction score, and were validated by previous mammalian and zebrafish microRNA profiling studies: dre-miR-124, -144, -148, -155, -19a, -223. The results of this in silico analysis indicate that several highly conserved miRNAs likely have a regulatory role of organismal responses to nanoparticles, and can possibly be used as biomarkers of nanotoxicity in studies using zebrafish as model organism One health approaches.

miR-let-7b and miR-let-7c suppress tumourigenesis of human mucosal melanoma and enhance the sensitivity to chemotherapy

Background

Mucosal melanoma with poor prognosis is a common histopathologic subtype of melanoma among Chinese and other Asian peoples. Regulated microRNAs (miRNAs) have been reported as oncogenes or tumour suppressors in melanoma. However, the roles of specific miRNAs in mucosal melanoma remain largely unknown. Here, we aimed to assess the biological functions, molecular mechanisms and clinical potential of miR-let-7b and miR-let-7c in mucosal melanoma.

Methods

The expression of miR-let-7b and miR-let-7c in mucosal melanoma was determined by quantitative polymerase chain reaction (qPCR). Cutoff scores for miR-let-7b and miR-let-7c expressions were calculated through receiver operating characteristic (ROC) curve analysis in 106 mucosal melanoma patients according to recurrence. Correlations of miR-let-7b and miR-let-7c expression with clinicopathological characteristics, disease-free survival (DFS) and clinical benefits after treatment were then statistically analysed. The biological functions and molecular mechanisms of miR-let-7b and miR-let-7c were studied in vitro and in vivo.

Results

The expression of miR-let-7b and miR-let-7c was decreased in 94 cases (88.7%) and 89 cases (84.0%) of 106 mucosal melanoma patients compared with mucosal nevi. A correlation was observed between the expression of miR-let-7b, miR-let-7c and DFS after surgery. In addition, overexpression of miR-let-7b or miR-let-7c inhibited mucosal melanoma cell growth, migration, invasion and metastasis and induced cell apoptosis and cell cycle arrest in vitro and in vivo. Mechanistically, miR-let-7b and miR-let-7c directly targeted metadherin (MTDH) and calumenin (CALU) and suppressed phospho-ERK in mucosal melanoma cells. MTDH and CALU reversed the partial function of miR-let-7b and miR-let-7c in vitro. Furthermore, progression-free survival (PFS) of mucosal melanoma patients upon temozolomide-based and paclitaxel-based chemotherapy was related to miR-let-7b and miR-let-7c expression. Overexpression of miR-let-7b or miR-let-7c in patient-derived xenograft (PDX) models and certain mucosal melanoma cells had better growth inhibition after temozolomide and paclitaxel treatment. MTDH reversed the sensitivity of miR-let-7b and miR-let-7c to paclitaxel in vitro.

Conclusions

Our results suggested that miR-let-7b and miR-let-7c inhibited the recurrence of mucosal melanoma through inhibiting cell growth, migration, invasion and metastasis, inducing cell apoptosis and cell cycle arrest by targeting MTDH and CALU. In addition, miR-let-7b and miR-let-7c increased sensitivity to chemotherapeutic agents by targeting MTDH.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1190-3) contains supplementary material, which is available to authorized users.