Role of microRNA-4516 involved autophagy associated with exposure to fine particulate matter

Epigenetic Mechanisms of Aluminum-Induced Neurotoxicity and Alzheimer's Disease: A Focus on Non-Coding RNAs

Aluminum (Al) is known to induce neurotoxic effects, potentially contributing to Alzheimer's disease (AD) pathogenesis. Recent studies suggest that epigenetic modification may contribute to Al neurotoxicity, although the mechanisms are still debatable. Therefore, the objective of the present study was to summarize existing data on the involvement of epigenetic mechanisms in Al-induced neurotoxicity, especially AD-type pathology. Existing data demonstrate that Al exposure induces disruption in DNA methylation, histone modifications, and non-coding RNA expression in brains. Alterations in DNA methylation following Al exposure were shown to be mediated by changes in expression and activity of DNA methyltransferases (DNMTs) and ten-eleven translocation proteins (TETs). Al exposure was shown to reduce histone acetylation by up-regulating expression of histone deacetylases (HDACs) and impair histone methylation, ultimately contributing to down-regulation of brain-derived neurotrophic factor (BDNF) expression and activation of nuclear factor κB (NF-κB) signaling. Neurotoxic effects of Al exposure were also associated with aberrant expression of non-coding RNAs, especially microRNAs (miR). Al-induced patterns of miR expression were involved in development of AD-type pathology by increasing amyloid β (Aβ) production through up-regulation of Aβ precursor protein (APP) and β secretase (BACE1) expression (down-regulation of miR-29a/b, miR-101, miR-124, and Let-7c expression), increasing in neuroinflammation through NF-κB signaling (up-regulation of miR-9, miR-125b, miR-128, and 146a), as well as modulating other signaling pathways. Furthermore, reduced global DNA methylation, altered histone modification, and aberrant miRNA expression were associated with cognitive decline in Al-exposed subjects. However, further studies are required to evaluate the contribution of epigenetic mechanisms to Al-induced neurotoxicity and/or AD development.

Toxicological Effects of Fine Particulate Matter (PM2.5): Health Risks and Associated Systemic Injuries-Systematic Review

Previous studies focused on investigating particulate matter with aerodynamic diameter ≤ 2.5 µm (PM2.5) have shown the risk of disease development, and association with increased morbidity and mortality rates. The current review investigate epidemiological and experimental findings from 2016 to 2021, which enabled the systemic overview of PM2.5's toxic impacts on human health. The Web of Science database search used descriptive terms to investigate the interaction among PM2.5 exposure, systemic effects, and COVID-19 disease. Analyzed studies have indicated that cardiovascular and respiratory systems have been extensively investigated and indicated as the main air pollution targets. Nevertheless, PM2.5 reaches other organic systems and harms the renal, neurological, gastrointestinal, and reproductive systems. Pathologies onset and/or get worse due to toxicological effects associated with the exposure to this particle type, since it can trigger several reactions, such as inflammatory responses, oxidative stress generation and genotoxicity. These cellular dysfunctions lead to organ malfunctions, as shown in the current review. In addition, the correlation between COVID-19/Sars-CoV-2 and PM2.5 exposure was also assessed to help better understand the role of atmospheric pollution in the pathophysiology of this disease. Despite the significant number of studies about PM2.5's effects on organic functions, available in the literature, there are still gaps in knowledge about how this particulate matter can hinder human health. The current review aimed to approach the main findings about the effect of PM2.5 exposure on different systems, and demonstrate the likely interaction of COVID-19/Sars-CoV-2 and PM2.5.

Unique regulatory roles of ncRNAs changed by PM2.5 in human diseases

PM_2.5 is a type of particulate matter with an aerodynamic diameter smaller than 2.5 µm, and exposure to PM_2.5 can adversely damage human health. PM_2.5 may impair health through oxidative stress, inflammatory reactions, immune function alterations and chromosome or DNA damage. Through increasing in-depth studies, researchers have found that noncoding RNAs (ncRNAs), particularly microRNAs (miRNAs), circular RNAs (circRNAs) as well as long noncoding RNAs (lncRNAs), might play significant roles in PM_2.5-related human diseases via some of the abovementioned mechanisms. Therefore, in this review, we mainly discuss the regulatory function of ncRNAs altered by PM_2.5 in human diseases and summarize the potential molecular mechanisms. The findings reveal that these ncRNAs might induce or promote diseases via inflammation, the oxidative stress response, cell autophagy, apoptosis, cell junction damage, altered cell proliferation, malignant cell transformation, disruption of synaptic function and abnormalities in the differentiation and status of immune cells. Moreover, according to a bioinformatics analysis, the altered expression of potential genes caused by these ncRNAs might be related to the development of some human diseases. Furthermore, some ncRNAs, including lncRNAs, miRNAs and circRNAs, or processes in which they are involved may be used as biomarkers for relevant diseases and potential targets to prevent these diseases. Additionally, we performed a meta-analysis to identify more promising diagnostic ncRNAs as biomarkers for related diseases.

Using a human bronchial epithelial cell-based malignant transformation model to explore the function of hsa-miR-200 family in the progress of PM2.5-induced lung cancer development

Numerous studies have revealed that ambient long-term exposure to fine particulate matter (PM_2.5) is significantly related to the development of lung cancer, but the molecular mechanisms of PM_2.5 exposure-induced lung cancer remains unknown. As an important epigenetic regulator, microRNAs (miRNAs) play vital roles in responding to environment exposure and various diseases including lung cancer development. Here we constructed a PM_2.5-induced malignant transformed cell model and found that miR-200 family, especially miR-200a-3p, was involved in the process of PM_2.5 induced lung cancer. Further investigation of the function of miR-200 family (miR-200a-3p as a representative revealed that miR-200a-3p promoted cell migration by directly suppressing TNS3 expression. These results suggested that ambient PM_2.5 exposure may increase the expression of miR-200 family and then promote the proliferation and migration of lung cancer cells. Our study provided novel model and insights into the molecular mechanism of ambient PM_2.5 exposure-induced lung cancer.

Epigenetic Regulation in Exposome-Induced Tumorigenesis: Emerging Roles of ncRNAs

Environmental factors, including pollutants and lifestyle, constitute a significant role in severe, chronic pathologies with an essential societal, economic burden. The measurement of all environmental exposures and assessing their correlation with effects on individual health is defined as the exposome, which interacts with our unique characteristics such as genetics, physiology, and epigenetics. Epigenetics investigates modifications in the expression of genes that do not depend on the underlying DNA sequence. Some studies have confirmed that environmental factors may promote disease in individuals or subsequent progeny through epigenetic alterations. Variations in the epigenetic machinery cause a spectrum of different disorders since these mechanisms are more sensitive to the environment than the genome, due to the inherent reversible nature of the epigenetic landscape. Several epigenetic mechanisms, including modifications in DNA (e.g., methylation), histones, and noncoding RNAs can change genome expression under the exogenous influence. Notably, the role of long noncoding RNAs in epigenetic processes has not been well explored in the context of exposome-induced tumorigenesis. In the present review, our scope is to provide relevant evidence indicating that epigenetic alterations mediate those detrimental effects caused by exposure to environmental toxicants, focusing mainly on a multi-step regulation by diverse noncoding RNAs subtypes.

MicroRNA profile as potential molecular signature for attention deficit hyperactivity disorder in children

AIMS

Attention deficit/hyperactivity disorder (ADHD) is a prevalent disorder of neurodevelopment in children. The diagnosis of ADHD mainly relies on the symptoms and some may be misdiagnosed due to age-based variation in behaviours. This study aimed to explore biomarkers that are greatly needed for the accurate diagnosis of ADHD.

METHODS

742 samples were retrospectively investigated in 3 independent cohorts, screening, training, and validation, for circulation microRNA measurement using microarray, Taqman polymerase chain reaction and regression analysis.

RESULTS

A panel of five miRNAs (miR-4516, miR-6090, miR-4763-3p, miR-4281 and miR-4466) were identified as ADHD independent risk factors that provided a high diagnostic accuracy and specificity of ADHD (AUC =0.940 and 0.927 in the training and validation datasets, respectively). This panel of miRNAs differentiated ADHD well from control groups. After clinical improvement by treatment, the panel of miRNAs in patients and AUC changed significantly, and were close to those in healthy controls. Importantly, the targets of the miRNAs identified were commonly enriched in receptor signalling pathways, ion channels and synapse structures.

CONCLUSION

Our study identified a useful panel of miRNAs that have considerable clinical value in evaluating ADHD and provide important evidence for aberrant epigenetic regulation in ADHD.

Spotlight on microRNAs in allergy and asthma

In past 10 years, microRNAs (miRNAs) have gained scientific attention due to their importance in the pathophysiology of allergic diseases and their potential as biomarkers in liquid biopsies. They act as master post‐transcriptional regulators that control most cellular processes. As one miRNA can target several mRNAs, often within the same pathway, dysregulated expression of miRNAs may alter particular cellular responses and contribute, or lead, to the development of various diseases. In this review, we give an overview of the current research on miRNAs in allergic diseases, including atopic dermatitis, allergic rhinitis, and asthma. Specifically, we discuss how individual miRNAs function in the regulation of immune responses in epithelial cells and specialized immune cells in response to different environmental factors and respiratory viruses. In addition, we review insights obtained from experiments with murine models of allergic airway and skin inflammation and offer an overview of studies focusing on miRNA discovery using profiling techniques and bioinformatic modeling of the network effect of multiple miRNAs. In conclusion, we highlight the importance of research into miRNA function in allergy and asthma to improve our knowledge of the molecular mechanisms involved in the pathogenesis of this heterogeneous group of diseases.

Biotoxic effects and gene expression regulation of urban PM2.5 in southwestern China

Atmospheric fine particulate matter (PM_2.5) causes severe haze in China and is regarded as a threat to human health. The health effects of PM_2.5 vary location by location due to the variation in size distribution, chemical composition, and sources. In this study, the cytotoxicity effect, oxidative stress, and gene expression regulation of PM_2.5 in Chengdu and Chongqing, two typical urban areas in southern China, were evaluated. Urban PM_2.5 in summer and winter significantly inhibited cell viability and increased reactive oxygen species (ROS) levels in A549 cells. Notably, PM_2.5 in winter exhibited higher cytotoxicity and ROS level than summer. Moreover, in this study, PM_2.5 commonly induced cancer-related gene expression such as cell adhesion molecule 1 (PECAM1), interleukin 24 (IL24), and cytochrome P450 (CYP1A1); meanwhile, PM_2.5 commonly acted on cancer-related biological functions such as cell-substrate junction, cell-cell junction, and focal adhesion. In particular, PM_2.5 in Chengdu in summer had the highest carcinogenic potential among PM_2.5 at the two sites in summer and winter. Importantly, cancer-related genes were uniquely targeted by PM_2.5, such as epithelial splicing regulatory protein 1 (ESRP1) and membrane-associated ring-CH-type finger 1 (1-Mar) by Chengdu summer PM_2.5; collagen type IX alpha 3 chain (COL9A3) by Chengdu winter PM_2.5; SH2 domain-containing 1B (SH2D1B) by Chongqing summer PM_2.5; and interleukin 1 receptor-like 1 (IL1RL1) and zinc finger protein 42 (ZNF423) by Chongqing winter PM_2.5. Meanwhile, important cancer-related biological functions were specially induced by PM_2.5, such as cell cycle checkpoint by Chengdu summer PM_2.5; macromolecule methylation by Chengdu winter PM_2.5; endoplasmic reticulum-Golgi intermediate compartment membrane by Chongqing summer PM_2.5; and cellular lipid catabolic process by Chongqing winter PM_2.5. Conclusively, in the typical urban areas of southern China, both summer and winter PM_2.5 illustrated significant gene regulation effects. This study contributes to evaluating the adverse health effects of PM_2.5 in southern China and providing public health suggestions for policymakers.

The Impact of Air Pollution Exposure on the MicroRNA Machinery and Lung Cancer Development

Small non-coding RNA molecules (miRNAs) play an important role in the epigenetic regulation of gene expression. As these molecules have been repeatedly implicated in human cancers, they have been suggested as biomarkers of the disease. Additionally, miRNA levels have been shown to be affected by environmental pollutants, including airborne contaminants. In this review, we searched the current literature for miRNAs involved in lung cancer, as well as miRNAs deregulated as a result of exposure to air pollutants. We then performed a synthesis of the data and identified those molecules commonly deregulated under both conditions. We detected a total of 25 miRNAs meeting the criteria, among them, miR-222, miR-21, miR-126-3p, miR-155 and miR-425 being the most prominent. We propose these miRNAs as biomarkers of choice for the identification of human populations exposed to air pollution with a significant risk of developing lung cancer.

Environmental Epigenetics of Diesel Particulate Matter Toxicogenomics

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by disruptions in social communication and behavioral flexibility. Both genetic and environmental factors contribute to ASD risk. Epidemiologic studies indicate that roadway vehicle exhaust and in utero exposure to diesel particulate matter (DPM) are associated with ASD. Using the Comparative Toxicogenomics Database (CTD), we identified genes connected to DPM exposure and ASD, extracted the known enhancers/promoters of the identified genes, and integrated this with Assay for Transposase Accessible Chromatin (ATAC-seq) data from DPM-exposed human neural progenitor cells. Enhancer/promoter elements with significantly different chromosome accessibility revealed enriched DNA sequence motifs with transcription factor binding sites for EGR1. Variant extraction for linkage disequilibrium blocks of these regions followed by analysis through Genome Wide Association Studies (GWAS) revealed multiple neurological trait associations including exploratory eye movement and brain volume measurement. This approach highlights the effects of pollution on the regulatory regions of genes implicated in ASD by genetic studies, indicating convergence of genetic and environmental factors on molecular networks that contribute to ASD. Integration of publicly available data from the CTD, cell culture exposure studies, and phenotypic genetics synergize extensive evidence of chemical exposures on gene regulation for altered brain development.

Lead exposure induces cell autophagy via blocking the Akt/mTOR signaling in rat astrocytes

Lead is a main threat to human health due to its neurotoxicity and the astrocyte is known to be a common deposit site of lead in vivo. However, the detailed mechanisms related to lead exposure in the astrocytes were unclear. In order to deeply investigate this issue, we used Sprague-Dawley (SD) rats and astrocytes isolated from the hippocampus of SD rats to establish the lead-exposed animal and cell models through treating with lead acetate. The expression levels of GFAP, LC3, and p62 in the rat hippocampus were detected by immunofluorescence and Western blot after lead exposure. The effects of autophagy on lead-exposed astrocytes were studied by further autophagy inhibitor 3-methyladenine (3-MA) induction. Transmission electron microscopy was used to observe autophagosomes in astrocytes after lead acetate treatment, followed by assessing related autophagy protein markers. In addition, some inflammatory cytokines and oxidative stress markers were also evaluated after lead exposure and 3-MA administration. We found that lead exposure induced activation of astrocytes, as evidenced by increased GFAP levels and GFAP-positive staining cells in the rat hippocampus. Moreover, lead exposure induced autophagy in astrocytes, as evidenced by increased LC3II and Beclin 1 protein levels and decreased p62 expression in both the rat hippocampus and astrocytes, and it was confirmed that this autophagy was activated through blocking the downstream Akt/target of the rapamycin (mTOR) pathway in astrocytes. Furthermore, it was shown that treatment of lead acetate increased the release of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β), and the accumulation of malondialdehyde (MDA) and myeloperoxidase (MPO) in astrocytes, which could be alleviated by further 3-MA induction. Therefore, we conclude that lead exposure can induce the autophagy of astrocytes via blocking the Akt/mTOR pathway, leading to accelerated release of inflammatory factors and oxidative stress indicators in astrocytes.

Melatonin Suppresses Renal Cortical Fibrosis by Inhibiting Cytoskeleton Reorganization and Mitochondrial Dysfunction through Regulation of miR-4516

Renal fibrosis, a major risk factor for kidney failure, can lead to chronic kidney disease (CKD) and is caused by cytoskeleton reorganization and mitochondrial dysfunction. In this study, we investigated the potential of melatonin treatment to reduce renal fibrosis by recovering the cytoskeleton reorganization and mitochondrial dysfunction. We found that miR-4516 expression was downregulated in the renal cortex of CKD mice and P-cresol-treated TH1 cells. Decreased miR-4516 expression stimulated cytoskeleton reorganization and mitochondrial dysfunction, and induced renal fibrosis. Melatonin treatment suppressed fibrosis by inhibiting cytoskeleton reorganization and restoring mitochondrial function via increased miR-4516 expression. More specifically, melatonin treatment increased miR-4516 expression while decreasing ITGA9 expression, thereby inhibiting cytoskeleton reorganization. In addition, increased expression of miR-4516 by melatonin treatment reduced ROS formation and restored mitochondrial function. These findings suggest that melatonin may be a promising treatment for patients with CKD having renal fibrosis. Moreover, regulation of miR-4516 expression may be a novel strategy for the treatment of renal fibrosis.

Role of non-coding-RNAs in response to environmental stressors and consequences on human health

Environmental risk factors, including physicochemical agents, noise and mental stress, have a considerable impact on human health. This environmental exposure may lead to epigenetic reprogramming, including changes in non-coding RNAs (ncRNAs) signatures, which can contribute to the pathophysiology state. Oxidative stress is one of the results of this environmental disturbance by modifying cellular processes such as apoptosis, signal transduction cascades, and DNA repair mechanisms. In this review, we delineate environmental risk factors and their influence on (ncRNAs) in connection to disease. We focus on well-studied miRNAs and analyze the novel roles of long-non-coding-RNAs (lncRNAs). We discuss commonly regulated lncRNAs after exposure to different stressors, such as UV, heavy metals and pesticides among others, and the potential role of these lncRNA as exposure biomarkers, epigenetic regulators and potential therapeutic targets to diminish the deleterious secondary response to environmental agents.

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Environmental stressors induce epigenetic changes that lead to long-lasting gene expression changes and pathology development.

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NcRNAs, miRNAs and lncRNAs, are epigenetic modifiers susceptible to changes in expression after environmental insults .

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LncRNAs influence cell function partnering with other biomolecules such as proteins, DNA, RNA or other ncRNAs.

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LncRNA dysregulation affects cell development, carcinogenesis, vascular disease and neurodegenerative disorders.

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ncRNA signatures can be potentially used as biomarkers to identify exposure to specific environmental stressors.

Current mechanistic perspectives on male reproductive toxicity induced by heavy metals

Environmental and occupational exposures to heavy metals have led to various deleterious damages to the biological system of which infertility is one of them. Infertility is a global public health concern, affecting 15% of all couples of reproductive age. Out of the 100% cases of reported infertility among couples, 40% of the cases are related to male factors; including decreased semen quality. This review focuses on the recent mechanistic perspectives of heavy metal-induced male reproductive toxicity. The associated toxic metal-mediated mechanisms of male reproductive toxicity include ion mimicry, disruption of cell signaling pathways, oxidative stress, altered gene expression, epigenetic regulation of gene expression, apoptosis, disruption of testis/blood barrier, inflammation and endocrine disruption. The current literature suggests that non-coding RNAs (ncRNAs) mediate paternal intergenerational epigenetic inheritance and thus has a direct functional importance, as well as possess novel biomarker potential, for male reproductive toxicity. To identify the specific ncRNAs with the most profound impacts on heavy metal-induced male reproductive toxicity should be thrust of further research.

MicroRNA-4516 suppresses pancreatic cancer development via negatively regulating orthodenticle homeobox 1

Pancreatic cancer remains one of the most lethal human cancers without efficient therapeutic strategy. MicoRNAs (miRNAs) are a group of small non-coding RNAs involved in multiple biological processes including tumor development and progression. In this study, we investigated the expression and function of miR-4516 in pancreatic cancer. MiR-4516 was low-expressed in pancreatic cancer tissues and cell lines. Overexpression of miR-4516 inhibited pancreatic cancer cell proliferation, migration and invasion, while promoted cell apoptosis in vitro. Further, overexpression of miR-4516 suppressed xenograft pancreatic tumor growth in vivo. Bioinformatics analysis was performed and miR-4516 was predicted to negatively regulate orthodenticle homeobox 1 (OTX1) expression by binding to its 3'-UTR. Consistently, OTX1 was highly expressed in pancreatic cancer tissues and cell lines. Knockdown of OTX1 expression suppressed pancreatic cancer cell migration and invasion, with down-regulated MMP2 and MMP9 expression. Moreover, we demonstrated that miR-4516 regulated pancreatic cancer cell growth, migration, invasion and apoptosis via targeting OTX1. Overexpression of OTX1 could partially abrogate the inhibitory effect of miR-4516. Taken together, we conclude that miR-4516 could function as a tumor suppressor via targeting OTX1. These findings suggest that miR-4516/OTX1 axis might be a novel therapeutic target for miRNA-based therapy for pancreatic cancer patients.

microRNAs expression in relation to particulate matter exposure: A systematic review

MicroRNAs (miRNAs) are a class of small, non-coding RNAs with a post-transcriptional regulatory function on gene expression and cell processes, including proliferation, apoptosis and differentiation. In recent decades, miRNAs have attracted increasing interest to explore the role of epigenetics in response to air pollution. Air pollution, which always contains kinds of particulate matters, are able to reach respiratory tract and blood circulation and then causing epigenetics changes. In addition, extensive studies have illustrated that miRNAs serve as a bridge between particulate matter exposure and health-related effects, like inflammatory cytokines, blood pressure, vascular condition and lung function. The purpose of this review is to summarize the present knowledge about the expression of miRNAs in response to particulate matter exposure. Epidemiological and experimental studies were reviewed in two parts according to the size and source of particles. In this review, we also discussed various functions of the altered miRNAs and predicted potential biological mechanism participated in particulate matter-induced health effects. More rigorous studies are worth conducting to understand contribution of particulate matter on miRNAs alteration and the etiology between environmental exposure and disease development.

Melatonin-stimulated exosomes enhance the regenerative potential of chronic kidney disease-derived mesenchymal stem/stromal cells via cellular prion proteins

Chronic kidney disease (CKD) is caused by dysfunctional kidneys, which result in complications like cardiovascular diseases. Chronic kidney disease-induced pathophysiological conditions decrease efficacy of autologous mesenchymal stem/stromal cell (MSC)-based therapy by reducing MSC functionality. To enhance therapeutic potential in patients with CKD, we isolated exosomes derived from melatonin-treated healthy MSCs (MT exosomes) and assessed the biological functions of MT exosome-treated MSCs isolated from patients with CKD (CKD-MSCs). Treatment with melatonin increased the expression of cellular prion protein (PrP^C ) in exosomes isolated from MSCs through the upregulation of miR-4516. Treatment with MT exosomes protected mitochondrial function, cellular senescence, and proliferative potential of CKD-MSCs. MT exosomes significantly increased the level of angiogenesis-associated proteins in CKD-MSCs. In a murine hindlimb ischemia model with CKD, MT exosome-treated CKD-MSCs improved functional recovery and vessel repair. These findings elucidate the regenerative potential of MT exosome-treated CKD-MSCs via the miR-4516-PrP^C signaling axis. This study suggests that the treatment of CKD-MSCs with MT exosomes might be a powerful strategy for developing autologous MSC-based therapeutics for patients with CKD. Furthermore, miR-4516 and PrP^C could be key molecules for enhancing the regenerative potential of MSCs in ischemic diseases.

MicroRNA Changes in Firefighters

Objectives:

Firefighters have elevated cancer incidence and mortality rates. MicroRNAs play prominent roles in carcinogenesis, but have not been previously evaluated in firefighters.

Methods:

Blood from 52 incumbent and 45 new recruit nonsmoking firefighters was analyzed for microRNA expression, and the results adjusted for age, obesity, ethnicity, and multiple comparisons.

Results:

Nine microRNAs were identified with at least a 1.5-fold significant difference between groups. All six microRNAs with decreased expression in incumbent firefighters have been reported to have tumor suppressor activity or are associated with cancer survival, and two of the three microRNAs with increased expression in incumbent firefighters have activities consistent with cancer promotion, with the remaining microRNA associated with neurological disease.

Conclusion:

Incumbent firefighters showed differential microRNA expression compared with new recruits, providing potential mechanisms for increased cancer risk in firefighters.

NF-κB-regulation of miR-155, via SOCS1/STAT3, is involved in the PM2.5-accelerated cell cycle and proliferation of human bronchial epithelial cells

Air pollution, especially fine particulate matter (PM_2.5, particles <2.5 μm in size), induces adverse health effects on the respiratory system. Uncontrolled proliferation of bronchial epithelial cells, resulting from deregulated cell cycle progression, contributes to pulmonary homeostatic imbalance. Although dysregulation of miRNAs is involved in a variety of pathophysiologic processes, the role of miRNAs in lung injury caused by PM_2.5 is unclear. In the present study, we found that different concentrations of PM_2.5 caused a biphasic effect on proliferation of human bronchial epithelial (HBE) cells. PM_2.5 induced an aberrant cell cycle and proliferation of HBE cells, and up-regulated miR-155 levels with a concentration-dependent manner. High miR-155 expression, mediated by NF-κB activation, produced an accelerated G1/S phase and cell proliferation though the STAT3 pathway, which targeted SOCS1. These findings indicate that NF-κB-mediated miR-155 induces an altered cell cycle through epigenetic modulation of the SOCS1/STAT3 signaling pathway and provide a mechanism for the biphasic effect of different concentrations of PM_2.5 in inducing respiratory injury.

A gapmer antisense oligonucleotide targeting SRRM4 is a novel therapeutic medicine for lung cancer

Small cell lung cancer (SCLC) is the most aggressive neuroendocrine phenotype of the deadliest human lung cancers. However the therapeutic landscape for SCLC has not changed in over 30 years. Effective treatment and prognosis are needed to combat this aggressive cancer. Herein we report that Ser/Arg repetitive matrix 4 (SRRM4), a splicing activator, is abnormally expressed at high levels in SCLC and thus is a potential therapeutic target. We screened an effective gapmer antisense oligonucleotide (gASO) targeting SRRM4 in vitro which led to cell death of SCLC. Our gASO, which is stabilized by containing artificial nucleotides, effectively represses SRRM4 mRNA. We found that our gASO repressed SRRM4 synthesis leading to a dramatic tumor reduction in a lung cancer mouse model. We also analyzed miRNA microarray and found that the miR-4516 is abnormally increased in exosomes in the blood of SCLC patients. Treating with gASO suppressed tumors in the SCLC model mouse concurrently reduced plasma miR-4516. In conclusion this study reports that administration of an SRRM4-targeted gASO coupled with a novel miRNA diagnostic methodology represents a potential breakthrough in the therapeutic treatment of high mortality SCLC.

Histone modification in the lung injury and recovery of mice in response to PM2.5 exposure

Epidemiological and experimental studies have progressively provided a better knowledge of the underlying mechanisms by which fine particulate matter (PM_2.5) exerts its harmful health effects. However, limited studies focused on the effect and following recovery after the particulate exposure ended. In this study, we determined PM_2.5 exposure-caused effects on the lung and their recovery in mice after terminating aspiration, and clarified the possible molecular modification. The results revealed that PM_2.5 exposure for 4 weeks significantly decreased the lung function, and the changes returned to normal levels after 1-week recovery. However, we observed persistent particle alveolar load following 2-week recovery. Interestingly, the alterations of H3K27ac expression and related enzyme activities mimicked the changes of respiratory function during the process, and chromatin immunoprecipitation-seqences (ChIP-seq) suggested that these PM_2.5-associated differential H3K27ac markers participated in immune responses and chemokine signaling pathway with stat2 and bcar1 being two important genes. Consistently, the expression of pro-inflammatory cytokines and chemokines elevated after PM_2.5 exposure for 4-week, and reversed to normal levels following 2-week recovery. The study highlighted that PM_2.5 aspiration caused histone modification associated lung dysfunction and inflammation, and the action restored after exposure ending and 2-week recovery. Also, persistent particle alveolar load might be a long-term potential risk for lung diseases.

Co-exposure to metals and polycyclic aromatic hydrocarbons, microRNA expression, and early health damage in coke oven workers

BACKGROUND

All humans are now co-exposed to multiple toxic chemicals, among which metals and polycyclic aromatic hydrocarbons (PAHs) are of special concern as they are often present at high levels in various human environments. They can also induce similar early health damage, such as genetic damage, oxidative stress, and heart rate variability (HRV). Exposure to metals, PAHs, and their combined pollutants can alter microRNA (miRNA) expression patterns.

OBJECTIVES

To explore the associations of metal-PAH co-exposure with miRNA expression, and of the associated miRNAs with early health damage.

METHODS

We enrolled 360 healthy male coke oven workers and quantified their exposure levels of metals and PAHs by urinary metals, urinary monohydroxy-PAHs (OH-PAHs), and plasma benzo[a]pyrene-r-7,t-8,t-9,c-10-tetrahydotetrol-albumin (BPDE-Alb) adducts, respectively. We selected and measured ten miRNAs: let-7b-5p, miR-126-3p, miR-142-5p, miR-150-5p, miR-16-5p, miR-24-3p, miR-27a-3p, miR-28-5p, miR-320b, and miR-451a. For miRNAs influenced by the effect modification of metals or PAHs and/or metal-PAH interactions, we further evaluated their associations with biomarkers for genetic damage, oxidative stress, and HRV.

RESULTS

After adjusting for PAHs and other metals, miRNA expression was found to be negatively associated with aluminum, antimony, lead, and titanium, and positively associated with molybdenum and tin (p < 0.05). Antimony showed modifying effects on the PAH-miRNA associations, while OH-PAHs and BPDE-Alb adducts modified the associations of metals with miRNAs (p for modifying effect < 0.05). Furthermore, miRNA expression was influenced by the antagonistic interactions between antimony and OH-PAHs, and by the synergistical interactions between metals and BPDE-Alb adducts (p_interaction < 0.05). Let-7b-5p, miR-126-3p, miR-16-5p, and miR-320b were additionally found to be associated with increased genetic damage in the present study [false discovery rate (FDR)-adjusted p < 0.05].

CONCLUSIONS

Associations of metal-PAH co-exposure with miRNA expression, and of associated miRNAs with early health damage, suggested potential mechanistic connections between the complex metal-PAH interactions and their deleterious effects that are worthy of further investigation.

miR-486 inhibits PM2.5-induced apoptosis and oxidative stress in human lung alveolar epithelial A549 cells

Background

Environmental exposure to particulate matter 2.5 (PM2.5) threatens public health, which has caused worldwide concerns. MicroRNAs (miRNAs, miRs) participate in multiple biological regulation. Among them, miR-486 has been reported to be a beneficial molecule for cell survival in various cell types. However, the potential function of miR-486 in PM2.5-induced cytotoxic is still uncertain.

Methods

The expression of miR-486 was detected by quantitative real-time polymerase chain reaction (qRT-PCR) after A549 cells incubated with PM2.5. Then TUNEL staining and DCFH-DA fluorescence were used to test the apoptosis and ROS generation of A549 cells after exposed to PM2.5 with miR-486 mimic. Western blot was performed to determine the expression of Bax/Bcl2 ratio. In addition, western blot and rescue experiments were conducted to determine the target gene of miR-486.

Results

After treated with PM2.5, the expression of miR-486 was decreased. And miR-486 mimic treatment reduced cell apoptosis and reactive oxygen species (ROS) generation induced by PM2.5 exposure. Further studies showed that miR-486 negatively regulated the protein levels of PTEN and FOXO1. Rescue experiments demonstrated that PTEN and FOXO1 mediated the protective effects of miR-486 in PM2.5-treated human lung alveolar epithelial A549 cells.

Conclusions

Collectively, our findings identify that miR-486 relieves PM2.5-induced cell injury by targeting PTEN and FOXO1 in human lung alveolar epithelial A549 cells.

The effects of autophagy on vascular endothelial cells induced by airborne PM2.5

The purpose of this study was to examine the direct toxicity of PM2.5 collected from Beijing on human umbilical vein endothelial cells (HUVEC). A Cell Counting Kit 8 (CCK8) assay demonstrated that PM2.5 exposure decreased the proliferation of HUVECs in a dose-dependent manner. We also found that PM2.5 exposure induced autophagy in HUVECs, as evidenced by: (1) an increased number of double-membrane vesicles; (2) enhanced conversion and punctuation of the microtubule-associated protein light chain 3 (LC3); and (3) decreased levels of the selective autophagy substrate p62 in a time-dependent manner. Furthermore, promoting autophagy in PM2.5-exposed HUVECs with rapamycin increased the cell survival rate, whereas inhibiting autophagy via 3-methyladenine significantly decreased cell survival. These results demonstrate that PM2.5 exposure can induce cytotoxicity and autophagy in HUVECs and that autophagy play a protective role against PM2.5-induced cytotoxicity. The findings of the present study imply a direct toxic effect of PM2.5 on HUVECs and provide novel insight into the mechanism of cardiovascular diseases caused by PM2.5 exposure.

Inhibition of miR-32 activity promoted EMT induced by PM2.5 exposure through the modulation of the Smad1-mediated signaling pathways in lung cancer cells

Epithelial mesenchymal transition (EMT) is a crucial morphological event during tumor progression. The present study reported that EMT could be triggered by airborne fine particulate matter (PM) with a mean diameter of less than 2.5 μm (PM2.5) in human lung cancer cells. We also aimed to elucidate the possible mechanisms of these processes. The results showed that treatment with PM2.5 promoted the activity of the SMAD family member 1 (Smad1)-mediated signaling pathway and downregulated the expression of the inhibitory Smad proteins Smad6 and Smad7 in lung cancer cells. Moreover, the knockdown of Smad1 suppressed the EMT process induced by PM2.5 exposure. Our data further revealed that miR-32 has a negative effect on PM2.5-induced EMT. The results showed that the expression level of miR-32 was significantly upregulated in the PM2.5-induced EMT process. The knockdown of miR-32 enhances the activity of the Smad1-mediated signaling pathway, which promotes the EMT process induced by PM2.5. Thus, these findings indicate that PM2.5 can induce the EMT process through the Smad1-mediated signaling pathway, and miR-32 may act as an EMT inhibitor in lung cancer cells.

XRCC1 mediated the development of cervival cancer through a novel Sp1/Krox-20 swich

Cervical cancer is the second leading cause of mortality among women. Impairment of the base excision repair (BER) pathway is one of the major causes of the initiation and progression of cervical cancer. However, whether the polymorphisms of the BER pathway components (i.e., HOGG1, XRCC1, ADPRT, and APE1) can affect the risk of cervical cancer remains unknown. Herein, we applied a hospital-based case-control study covering two independent cohorts and a subsequent functional assay to determine the roles of the single nucleotide polymorphisms (SNPs) of the BER pathway genes in cervical cancer. Results indicated that the XRCC1 rs3213245 (-77TC) TT genotype was associated with an increased risk of cervical cancer. The immunohistochemistry assay showed that XRCC1 protein expression levels were upregulated in cervical cancer patients with the XRCC1 rs3213245 CC genotype compared with the CT or TT genotypes. Further, results from ChIP assay showed that Sp1 could bind to the −77 site and that the rs3213245 C genotype promoted the binding of Sp1 to the XRCC1 promoter. Moreover, ChIP/Re-ChIP assays revealed that transcription factor Krox-20 was recruited to the XRCC1 rs3213245 mutation region and regulated the transcription of the XRCC1 gene by interacting with Sp1, ultimately mediated cervical cancer development. In summary, the findings indicated that the functional XRCC1 SNP rs3213245 was associated with the risk of cervical cancer based on the Sp1/Krox-20 switch.

Genome-wide miRNA response to anacardic acid in breast cancer cells

MicroRNAs are biomarkers and potential therapeutic targets for breast cancer. Anacardic acid (AnAc) is a dietary phenolic lipid that inhibits both MCF-7 estrogen receptor α (ERα) positive and MDA-MB-231 triple negative breast cancer (TNBC) cell proliferation with IC50s of 13.5 and 35 μM, respectively. To identify potential mediators of AnAc action in breast cancer, we profiled the genome-wide microRNA transcriptome (microRNAome) in these two cell lines altered by the AnAc 24:1n5 congener. Whole genome expression profiling (RNA-seq) and subsequent network analysis in MetaCore Gene Ontology (GO) algorithm was used to characterize the biological pathways altered by AnAc. In MCF-7 cells, 69 AnAc-responsive miRNAs were identified, e.g., increased let-7a and reduced miR-584. Fewer, i.e., 37 AnAc-responsive miRNAs were identified in MDA-MB-231 cells, e.g., decreased miR-23b and increased miR-1257. Only two miRNAs were increased by AnAc in both cell lines: miR-612 and miR-20b; however, opposite miRNA arm preference was noted: miR-20b-3p and miR-20b-5p were upregulated in MCF-7 and MDA-MB-231, respectively. miR-20b-5p target EFNB2 transcript levels were reduced by AnAc in MDA-MB-231 cells. AnAc reduced miR-378g that targets VIM (vimentin) and VIM mRNA transcript expression was increased in AnAc-treated MCF-7 cells, suggesting a reciprocal relationship. The top three enriched GO terms for AnAc-treated MCF-7 cells were B cell receptor signaling pathway and ribosomal large subunit biogenesis and S-adenosylmethionine metabolic process for AnAc-treated MDA-MB-231 cells. The pathways modulated by these AnAc-regulated miRNAs suggest that key nodal molecules, e.g., Cyclin D1, MYC, c-FOS, PPARγ, and SIN3, are targets of AnAc activity.

Exosomes derived from miR-140-5p-overexpressing human synovial mesenchymal stem cells enhance cartilage tissue regeneration and prevent osteoarthritis of the knee in a rat model

OBJECTIVES

Osteoarthritis (OA) is the most common joint disease throughout the world. Exosomes derived from miR-140-5p-overexpressing synovial mesenchymal stem cells (SMSC-140s) may be effective in treating OA. We hypothesized that exosomes derived from SMSC-140 (SMSC-140-Exos) would enhance the proliferation and migration abilities of articular chondrocytes (ACs) without harming extracellular matrix (ECM) secretion.

METHODS

SMSCs were transfected with or without miR-140-5p. Exosomes derived from SMSCs or SMSC-140s (SMSC-Exos or SMSC-140-Exos) were isolated and identified. Proliferation, migration and ECM secretion were measured in vitro and compared between groups. The mechanism involving alternative Wnt signalling and activation of Yes-associated protein (YAP) was investigated using lentivirus, oligonucleotides or chemical drugs. The preventative effect of exosomes in vivo was measured using Safranin-O and Fast green staining and immunohistochemical staining.

RESULTS

Wnt5a and Wnt5b carried by exosomes activated YAP via the alternative Wnt signalling pathway and enhanced proliferation and migration of chondrocytes with the side-effect of significantly decreasing ECM secretion. Highly-expressed miR-140-5p blocked this side-effect via RalA. SMSC-140-Exos enhanced the proliferation and migration of ACs without damaging ECM secretion in vitro, while in vivo, SMSC-140-Exos successfully prevented OA in a rat model.

CONCLUSIONS

These findings highlight the promising potential of SMSC-140-Exos in preventing OA. We first found a potential source of exosomes and studied their merits and shortcomings. Based on our understanding of the molecular mechanism, we overcame the shortcomings by modifying the exosomes. Such exosomes derived from modified cells hold potential as future therapeutic strategies.