Analysis of MicroRNA Expression Profiling Involved in MC-LR-Induced Cytotoxicity by High-Throughput Sequencing

Microcystin-RR promote lipid accumulation through CD36 mediated signal pathway and fatty acid uptake in HepG2 cells

Microcystins (MC)-RR is a significant analogue of MC-LR, which has been identified as a hepatotoxin capable of influencing lipid metabolism and promoting the progression of liver-related metabolic diseases. However, the toxicity and biological function of MC-RR are still not well understood. In this study, the toxic effects and its role in lipid metabolism of MC-RR were investigated in hepatoblastoma cells (HepG2cells). The results demonstrated that MC-RR dose-dependently reduced cell viability and induced apoptosis. Additionally, even at low concentrations, MC-RR promoted lipid accumulation through up-regulating levels of triglyceride, total cholesterol, phosphatidylcholines and phosphatidylethaolamine in HepG2 cells, with no impact on cell viability. Proteomics and transcriptomics analysis further revealed significant alterations in the protein and gene expression profiles in HepG2 cells treated with MC-RR. Bioinformatic analysis, along with subsequent validation, indicated the upregulation of CD36 and activation of the AMPK and PI3K/AKT/mTOR in response to MC-RR exposure. Finally, knockdown of CD36 markedly ameliorated MC-RR-induced lipid accumulation in HepG2 cells. These findings collectively suggest that MC-RR promotes lipid accumulation in HepG2 cells through CD36-mediated signal pathway and fatty acid uptake. Our findings provide new insights into the hepatotoxic mechanism of MC-RR.

Microcystin-LR-induced autophagy via miR-282-5p/PIK3R1 pathway in Eriocheir sinensis hepatopancreas

With the intensifying climate warming, blue-green algae blooms have become more frequent and severe, releasing environmental hazards such as microcystin that pose potential threats to human and animal health. Autophagy has been shown to play a crucial role in regulating immune responses induced by environmental hazards, enabling cells to adapt to stress and protect against damage. Although microcystin-LR (MC-LR) has been identified to affect autophagy in mammalian, its impact on aquatic animals has been poorly studied. To investigate the toxicological effects of MC-LR in aquatic ecosystems, we constructed a microRNA profile of acute MC-LR stress in the hepatopancreas of the Chinese mitten crab. Interestingly, we found the MC-LR exposure activated autophagy in the hepatopancreas based on the following evidence. Specifically, mRNA expression level of ATG7, Beclin1 and Gabarap was significantly up-regulated, autophagy regulatory pathways were significantly enriched, and numerous autolysosomes and autophagosomes were observed. Additionally, we found that miR-282-5p and its target gene PIK3R1 played important regulatory roles in autophagy by in vivo and in vitro experiments. Overexpression of miR-282-5p mimicked MC-LR-induced autophagy by inhibiting PIK3R1 expression, while miR-282-5p silencing inhibited autophagy by promoting PIK3R1 expression. Altogether, our findings suggest that MC-LR increases miR-282-5p, which then targets inhibition of PIK3R1 to stimulate autophagy. This study focused on the stress response regulatory mechanisms of juvenile crabs to toxic pollutants in water, offering a potential target for alleviating the toxicity of MC-LR. These findings lay a foundation for reducing the toxicity of MC-LR and environmental hazards in organisms.

miR-146a-5p Promotes the Inflammatory Response in PBMCs Induced by Microcystin-Leucine-Arginine

Background

Microcystin-leucine-arginine (MC-LR) is the most abundant and most toxic variant of microcystin isomers. Various experiments have clearly shown that MC-LR has hepatotoxicity and carcinogenicity, but there are relatively few studies on its immune damage effect. In addition, numerous studies have shown that microRNAs (miRNAs) are involved in a wide range of biological processes. Do miRNAs also play a role in inflammatory response caused by microcystin exposure? This is the question to be answered in this study. Moreover, this study can also provides experimental evidence for the significance of miRNA applications.

Objective

To investigate the effect of MC-LR on the expressions of miR-146a and pro/anti-inflammatory cytokines in human peripheral blood mononuclear cells (PBMCs) and to further explore the role of miR-146a in the inflammatory responses caused by MC-LR.

Methods

Serum samples from 1789 medical examiners were collected and detect the concentrations of MCs, and 30 serum samples with concentrations of MCs around P₂₅, P₅₀, and p₇₅ were randomly selected for the detection of inflammatory factors. PBMCs from fresh peripheral blood extracted from these 90 medical examiners were subsequently tested for relative miR-146a expression. In vitro, the MC-LR were exposed to the PBMCs to detect the levels of inflammatory factors as well as the relative expression of miR-146a-5p. Then, a miRNA transfection assay was performed to verify the regulation of inflammatory factors by miR-146a-5p.

Results

In population samples, the expression of inflammatory factors and miR-146a-5p increased with increasing MCs concentration. In vitro experiments showed that the expression of inflammatory factors and miR-146a-5p in PBMCs increased with MC-LR exposure time or exposure dose too. In addition, inhibiting the expression of miR-146a-5p in PBMCs reduced inflammatory factor levels.

Conclusion

miR-146a-5p exerts a promoting effect on the MC-LR-induced inflammatory response by positively regulating inflammatory factor levels.

Microcystin-LR in Primary Liver Cancers: An Overview

The cyanobacterial blooms produced by eutrophic water bodies have become a serious environmental issue around the world. After cellular lysing or algaecide treatment, microcystins (MCs), which are regarded as the most frequently encountered cyanobacterial toxins in fresh water, are released into water. Among all the variants of MCs, MC-LR has been widely studied due to its severe hepatotoxicity. Since 1992, various studies have identified the important roles of MC-LR in the origin and progression of primary liver cancers (PLCs), although few reviews have focused on it. Therefore, this review aims to summarize the major achievements and shortcomings observed in the past few years. Based on the available literature, the mechanisms of how MC-LR induces or promotes PLCs are elucidated in this review. This review aims to enhance our understanding of the role that MC-LR plays in PLCs and provides a rational approach for future applications.

Negative impacts of microcystin-LR and glyphosate on zebrafish intestine: Linked with gut microbiota and microRNAs?

Microcystin-LR (MC-LR) and glyphosate (GLY) have been classified as a Group 2B and Group 2A carcinogens for humans, respectively, and frequently found in aquatic ecosystems. However, data on the potential hazard of MC-LR and GLY exposure to the fish gut are relatively scarce. In the current study, a subacute toxicity test of zebrafish exposed to MC-LR (35 μg L-1) and GLY (3.5 mg L-1), either alone or in combination was performed for 21 d. The results showed that MC-LR or/and GLY treatment reduced the mRNA levels of tight junction genes (claudin-5, occludin, and zonula occludens-1) and altered the levels of diamine oxidase and D-lactic, indicating increased intestinal permeability in zebrafish. Furthermore, MC-LR and/or GLY treatment remarkably increased the levels of intestinal IL-1β and IL-8 but decreased the levels of IL-10 and TGF-β, indicating that MC-LR and/or GLY exposure induced an inflammatory response in the fish gut. MC-LR and/or GLY exposure also activated superoxide dismutase and catalase, generally upregulated the levels of p53, bax, bcl-2, caspase-3, and caspase-9, downregulated the levels of caspase-8 and caused notable histological injury in the fish gut. Moreover, MC-LR and/or GLY exposure also significantly altered the microbial community in the zebrafish gut and the expression of miRNAs (miR-146a, miR-155, miR-16, miR-21, and miR-223). Chronic exposure to MC-LR and/or GLY can induce intestinal damage in zebrafish, and this study is the first to demonstrate an altered gut microbiome and miRNAs in the zebrafish gut after MC-LR and GLY exposure.

Advances in the toxicology research of microcystins based on Omics approaches

Microcystins (MCs) are the most widely distributed cyanotoxins, which can be ingested by animals and human body in multiple ways, resulting in a threat to human health and the biodiversity of wildlife. Therefore, the study on toxic effects and mechanisms of MCs is one of the focuses of attention. Recently, the Omics techniques, i.e. genomics, transcriptomics, proteomics and metabolomics, have significantly contributed to the comprehensive understanding and revealing of the molecular mechanisms about the toxicity of MCs. This paper mainly reviews current literature using the Omics approaches to explore the toxicity mechanism of MCs in liver, gonad, spleen, brain, intestine and lung of multiple species. It was found that MCs can exert strong toxic effects on various metabolic activities and cell signal transduction in cell cycle, apoptosis, destruction of cell cytoskeleton and redox disorder, at protein, transcription and metabolism level. Meanwhile, it was also revealed that the alteration of non-coding RNAs (miRNA, circRNA and lncRNA, etc.) and gut microbiota plays an essential regulatory role in the toxic effects of MCs, especially in hepatotoxicity and reproductive toxicity. In addition, we summarized current research gaps and pointed out the future directions for research. The detailed information in this paper shows that the application and development of Omics techniques have significantly promoted the research on MCs toxicity, and it is also a valuable resource for exploring the toxic mechanism of MCs.

EWI-2 controls nucleocytoplasmic shuttling of EGFR signaling molecules and miRNA sorting in exosomes to inhibit prostate cancer cell metastasis

Early and accurate diagnosis of prostate cancer (PCa) is extremely important, as metastatic PCa remains hard to treat. EWI-2, a member of the Ig protein subfamily, is known to inhibit PCa cell migration. In this study, we found that EWI-2 localized on both the cell membrane and exosomes regulates the distribution of miR-3934-5p between cells and exosomes. Interestingly, we observed that EWI-2 is localized not only on the plasma membrane but also on the nuclear envelope (nuclear membrane), where it regulates the nuclear translocation of signaling molecules and miRNA. Collectively, these functions of EWI-2 found in lipid bilayers appear to regulate PCa cell metastasis through the epidermal growth factor receptor-mitogen-activated protein kinase-extracellular-signal-regulated kinase (EGFR-MAPK-ERK) pathway. Our research provides new insights into the molecular function of EWI-2 on PCa metastasis, and highlights EWI-2 as a potential PCa biomarker.

MicroRNA-363-3p Inhibits the Expression of Renal Fibrosis Markers in TGF-β1-Treated HK-2 Cells by Targeting TGF-β2

This study aimed to explore the role of miR-363-3p in renal fibrosis (RF) in vitro. HK-2 cells were treated with transforming growth factor (TGF)-β1 for 72 h to establish an in vitro model of RF. Subsequently, western blot analysis and reverse transcription-quantitative PCR were used to detect the protein and mRNA expression levels of RF markers in TGF-β1-treated HK-2 cells, respectively. The results showed that the protein and mRNA expression levels of TGF-β2, α-smooth muscle actin (SMA), fibronectin, vimentin, collagen II and N-cadherin were increased, while the protein and mRNA expression levels of E-cadherin were decreased in TGF-β1-treated HK-2 cells. The level of miR-363-3p was significantly decreased in TGF-β1-treated HK-2 cells. TargetScan indicated that TGF-β2 was a direct target gene for miR-363-3p, which was further verified using dual luciferase reporter gene assays. Further analyses revealed that the increased protein and mRNA expression levels of TGF-β2, α-SMA, fibronectin, vimentin, collagen II, N-cadherin, increased phosphorylated-Smad3 protein level, and decreased E-cadherin protein and mRNA expression in TGF-β1-treated HK-2 cells were significantly reversed by miR-363-3p mimics. However, all the effects were suppressed by a TGF-β2-plasmid. The results suggested that miR-363-3p plays a protective role in RF by regulating the TGF-β2/Smad3 signaling pathway.

MicroRNAs and Xenobiotic Toxicity: An Overview

The advent of new technologies has paved the rise of various chemicals that are being employed in industrial as well as consumer products. This leads to the accumulation of these xenobiotic compounds in the environment where they pose a serious threat to both target and non-target species. miRNAs are one of the key epigenetic mechanisms that have been associated with toxicity by modulating the gene expression post-transcriptionally. Here, we provide a comprehensive view on miRNA biogenesis, their mechanism of action and, their possible role in xenobiotic toxicity. Further, we review the recent in vitro and in vivo studies involved in xenobiotic exposure induced miRNA alterations and the mRNA-miRNA interactions. Finally, we address the challenges associated with the miRNAs in toxicological studies.

CircMACF1 Attenuates Acute Myocardial Infarction Through miR-500b-5p-EMP1 Axis

It is widely accepted that circular RNA (circRNA) plays an important role in cardiovascular diseases. Therefore, this experiment aimed to investigate the pathogenesis of circMACF1 in acute myocardial infarction (AMI). qRT-PCR and immunoblotting were used to detect the expression levels of circMACF1, miR-500b-5p, and epithelial membrane protein 1 (EMP1). The role of circMACF1, miR-500b-5p, and EMP1 in cardiomyocyte apoptosis was assessed using annexin V-FITC/PI. Echocardiographic assessment, serum creatine kinase MB (CK-MB) and lactate dehydrogenase (LDH), myocardial infarct size, and TUNEL staining were applied in our research. In the MI group, the expression levels of circMACF1 and EMP1 were decreased with the increasing expression level of miR-500b-5p. CircMACF1 upregulated the expression of EMP1 as a sponge of miR-500b-5p, and circMACF1 was a direct target of miR-500b-5p. CircMACF1 impaired the progression of AMI by modulating the miR-500b-5p/EMP1 axis. CircMACF1 may be a potential therapeutic target for treating AMI. Graphical Abstract CircMACF1 upregulated EMP1 expression by sponge miR-500b-5p.

Aberrant Expressional Profiling of Known MicroRNAs in the Liver of Silver Carp (Hypophthalmichthys molitrix) Following Microcystin-LR Exposure Based on samllRNA Sequencing

Microcystin-LR (MC-LR) poses a serious threat to human health due to its hepatotoxicity. However, the specific molecular mechanism of miRNAs in MC-LR-induced liver injury has not been determined. The aim of the present study was to determine whether miRNAs are regulated in MC-LR-induced liver toxicity by using high-throughput sequencing. Our research demonstrated that 53 miRNAs and 319 miRNAs were significantly changed after 24 h of treatment with MC-LR (50 and 200 μg/kg, respectively) compared with the control group. GO enrichment analysis revealed that these target genes were related to cellular, metabolic, and single-organism processes. Furthermore, KEGG pathway analysis demonstrated that the target genes of differentially expressed miRNAs in fish liver were primarily involved in the insulin signaling pathway, PPAR signaling pathway, Wnt signaling pathway, and transcriptional misregulation in cancer. Moreover, we hypothesized that 4 miRNAs (miR-16, miR-181a-3p, miR-451, and miR-223) might also participate in MC-LR-induced toxicity in multiple organs of the fish and play regulatory roles according to the qPCR analysis results. Taken together, our results may help to elucidate the biological function of miRNAs in MC-LR-induced toxicity.

MicroRNA-665 promotes the proliferation of ovarian cancer cells by targeting SRCIN1

Recent studies have discovered several microRNAs (miRNAs/miRs) as biomarkers for the prediction of ovarian cancer by detecting miRNA profiles in serum samples from healthy volunteers and patients with ovarian cancer. However, whether and how these miRNAs are involved in tumorigenesis is not known. In the present study, the expression of miR-665, a recently discovered biomarker for ovarian cancer, was upregulated in tumor tissues from patients with ovarian cancer compared with normal tissues. Inhibition of miR-665 inhibited cell proliferation ability and inactivated MAPK/ERK signaling of ovarian cancer cells. Using bioinformatics analysis, Src kinase signaling inhibitor 1 (SRCIN1) was predicted as a potential target gene of miR-665. Reverse transcription-quantitative PCR and western blotting showed that SRCIN1 expression was repressed by miR-665 in ovarian cancer cells. In addition, a dual luciferase activity assay showed that SRCIN1 was a target gene of miR-665. Silencing of SRCIN1 could reverse the cell growth arrest, which was induced by the miR-665 inhibitor. Moreover, miR-665 levels were negatively correlated with SRCIN1 mRNA levels in tumor tissues from patients with ovarian cancer. In conclusion, the present data suggested that miR-665 functioned as an oncogene in ovarian cancer by directly repressing the expression of SRCIN1.

CYP3A4 and microRNA-122 are involved in the apoptosis of HepG2 cells induced by ILs 1-decyl-3-methylimidazolium bromide

Ionic liquids (ILs) as green alternatives for volatile organic solvents are increasingly used in commercial applications. It is necessary to explore the cytotoxic mechanism of ILs to reduce the risk to human health. For this purpose, cell viability, apoptosis, cytochrome P450 3A4 (CYP3A4), glucose transporter type 2 (GLUT2), and microRNA-122 (miR-122) gene expression in HepG2 cells was evaluated after IL exposure. The results showed that ILs reduced the viability of HepG2 cells through apoptotic cell death. Moreover, ILs markedly upregulated the transcription and protein levels of CYP3A4, but did not affect the expression of GLUT2 in either messenger RNA level or protein level. Finally, ILs increased the expression of miR-122 and inhibition of miR-122 with miR-122 inhibitor blocked ILs-induced apoptosis in HepG2 cells. This finding may contribute to an increased understanding of the in vitro molecular toxicity mechanism of ILs to further understand IL-related human health risks.

Regulation of Microcystin-LR-Induced DNA Damage by miR-451a in HL7702 Cells

Microcystin-LR is a cyclic heptapeptide hepatotoxin produced by harmful cyanobacteria. A panel of microRNAs containing miR-451a were found to be significantly changed in normal human liver cells HL7702 after exposure to microcystin-LR (MC-LR) in our previous study. However, the functions of miR-451a in hepatotoxicity induced by MC-LR remained unclear. The study aimed to investigate the impacts of miR-451a in HL7702 cells following treatment with 5 or 10 μM MC-LR. The comet assay indicated that MC-LR can influence Olive tail moment (OTM) in HL7702 cells. Furthermore, increase of miR-451a significantly repressed DNA damage and the protein expression level of γ-H2AX induced by MC-LR. Moreover, over-expression of miR-451a inhibited the expression level of p-AKT1 protein in cells following treatment by MC-LR. These results showed that miR-451a may protect from MC-LR-induced DNA damage by down-regulating the expression of p-AKT1, which provides new clues for the diagnosis and therapy policies for liver damage induced by MC-LR.

Molecular characterization of the cyclin-dependent protein kinase 6 in whitefish (Coregonus lavaretus) and its potential interplay with miR-34a

Cyclin-dependent protein kinase 6 (CDK6) plays a pivotal role in the regulation of the cell cycle and cell proliferation in mammals, and disruption of its expression by various microRNAs has been implicated in the pathogenesis of multiple human cancers. In mammals, miR-34a acts as a downstream effector of p53, and thus indirectly targets Cdk6, abrogating its effects. However, no studies have been done so far to examine the mechanistic involvement of miR-34a in the silencing of cdk6 in fish. In the present study, we found that the cDNA sequence of whitefish cdk6 has a 3'UTR region that contains a binding site for miR-34a. Using a luciferase reporter assay, we demonstrated that whitefish cdk6 is a direct target of miR-34a in vitro. In order to confirm this relationship in vivo, we measured the miR-34a and cdk6 mRNA expression patterns in the liver of whitefish after short-term (8, 24, and 48 h) and long-term (14 and 28 days) exposure to microcystin-LR (MC-LR), a known hepatotoxin and tumor promoter. In contrast to the in vitro findings, we noticed an up-regulation of miR-34a and cdk6 expression after long-term MC-LR treatment. While these results indicate that both, miR-34a and cdk6 are responsive to MC-LR treatment, they do not support the presence of a miR-34a:cdk6 mRNA regulatory pair in the MC-LR-challanged whitefish liver in vivo. On the other hand, our findings suggests that cell regulatory elements, partnering with either miR-34a or cdk6, are worthy of further screening to better understand the molecular mechanisms that underlie the physiological response of fish challenged with hepatotoxic environmental pollutants like microcystins.

Extracellular vesicle‑delivered miR‑505‑5p, as a diagnostic biomarker of early lung adenocarcinoma, inhibits cell apoptosis by targeting TP53AIP1

Lung adenocarcinoma (LA) is the most commonly occurring histological type of non‑small cell lung cancer. Diagnosis and treatment of LA remain a major clinical challenge. In the present study, to identify early LA biomarkers, extracellular vesicles (EVs) were separated from the plasma samples from 153 patients with LA and 75 healthy controls. microRNA (miRNA) expression profiling was performed at the screening stage (5 patients with LA vs. 5 controls), followed by verification at the validation stage (40 patients with LA vs. 20 controls) using reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR). The four disordered miRNAs (miR‑505‑5p, miR‑486‑3p, miR‑486‑3p and miR‑382‑3p) identified in the plasma EVs were further evaluated at the testing stage (108 patients with LA vs. 50 controls) by RT‑qPCR. It was revealed that miR‑505‑5p was upregulated, whereas miR‑382‑3p was downregulated, in the EVs from patients with LA. Furthermore, miR‑505‑5p was also upregulated in tumor tissues, compared with adjacent non‑tumor control tissues. Subsequently, the direct targets of miR‑505‑5p were predicted using bioinformatics analyses, and verified by luciferase assay and immunoblotting. The present study determined that miR‑505‑5p functions as an oncogene, promoting lung cancer cell proliferation and inhibiting cancer cell apoptosis via the targeting of tumor protein P53‑regulated apoptosis‑inducing protein 1 (TP53AIP1). Finally, it was confirmed that miR‑505‑5p in plasma EVs could be delivered to lung cancer cells, inhibiting cell apoptosis and promoting cell proliferation by targeting TP53AIP1. In conclusion, the present study indicated that miRNA‑505‑5p functions as an oncogene that may be used as a novel biomarker for the diagnosis and treatment of LA.

Chronic exposure to the ionic liquid [C8mim]Br induces inflammation in silver carp spleen: Involvement of oxidative stress-mediated p38MAPK/NF-κB signalling and microRNAs

The present study aimed to determine the chronic toxicity of 1-methyl-3-octylimidazolium bromide ([C₈mim]Br) on the silver carp to further reveal the toxicological mechanisms of ionic liquids. Chronic exposure of silver carp to [C₈mim]Br at concentrations of 1.095 and 4.380 mg/L for 60 d was conducted under laboratory conditions. The results revealed that chronic exposure to [C₈mim]Br inhibited the activity of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) and reduced glutathione (GSH) levels while markedly increasing malondialdehyde (MDA) and protein carbonyl (PC) levels in fish spleen, indicating that [C₈mim]Br treatment induced oxidative stress. Additionally, long-term exposure to [C₈mim]Br markedly upregulated the expressions of nuclear factor-κB (NF-κB), inducible nitric oxide synthase (iNOS), interleukin-1β (IL-1β), IL-6, tumour necrosis factor-α (TNF-α), and interferon-γ (IFN-γ); altered the levels of transforming growth factor-β (TGF-β); and increased the mRNA levels of p38MAPK, c-fos, c-jun, and c-myc, suggesting that long-term exposure to [C₈mim]Br might promote the inflammatory response in fish spleen and that p38MAPK/NF-κB signalling may potentially be involved in this process. Moreover, [C₈mim]Br-exposure altered lysozyme activity and complement 3 (C3) and immunoglobulin M (IgM) content, indicating that chronic [C₈mim]Br exposure also has immunotoxic effects on silver carp. Furthermore, we also found that [C₈mim]Br exposure reduced miR-125b levels, altered miR-143 levels, and upregulated miR-155 and miR-21 levels, suggesting that these miRNAs may be involved in the [C₈mim]Br-induced inflammatory response in fish spleen. In summary, the present study indicates that chronic exposure to [C₈mim]Br induces inflammation in fish spleen and that oxidative stress-mediated p38MAPK/NF-κB signalling and miRNAs may play a key role in this process.

MicroRNA‑363‑3p inhibits hepatocarcinogenesis by targeting HMGA2 and is associated with liver cancer stage

The importance of microRNAs (miRNAs) in cancer development has been widely recognized in recent decades. In the present study, the function and mechanism of miRNA-363-3p (miR-363-3p), formerly characterized as a tumor suppressor, in the hepatocarcinogenesis of liver cancer cells was investigated. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was applied to detect the expression of miR-363-3p in liver cancer tissues. Cell proliferation, survival and migration capacities were determined by MTT, colony formation and wound-healing assays, respectively. The targeting of high mobility group AT-hook 2 (HMGA2) mRNA by miR-363-3p was confirmed by bioinformatics analysis, and RT-qPCR, luciferase reporter and western blot assays. The correlation between the expression levels of HMGA2 and miR-363-3p was analyzed. The RT-qPCR results revealed that the levels of miR-363-3p were downregulated in liver cancer tissues. Cellular assays validated that miR-363-3p exerted tumor suppressing functions, including the inhibition of cell proliferation, survival and migration abilities in two liver cancer cell lines. Bioinformatics prediction and subsequent experiments demonstrated that HMGA2 was a direct target of miR-363-3p. Restoration of the expression of HMGA2 in miR-363-3p mimic-transfected cells reversed the tumor suppressing effects caused by miR-363-3p. Finally, there was a significant negative correlation between the expression levels of HMGA2 and miR-363-3p in liver cancer tissues. miR-363-3p was identified as an important tumor suppressor in liver cancer via targeting HMGA2, which may have potential benefits in liver cancer therapy.

Exposure routes and health effects of microcystins on animals and humans: A mini-review

Microcystins (MCs) pollution has quickly risen in infamy and has become a major problem to public health worldwide. MCs are a group of monocyclic hepatotoxic peptides, which are produced by some bloom-forming cyanobacteria in water. More than 100 different MCs variants posing a great threat to animals and humans due to their potential carcinogenicity have been reported. To reduce MCs risks, the World Health Organization has set a provisional guideline of 1 μg/L MCs in human's drinking water. This paper provides an overview of exposure routes of MCs into the human system and health effects on different organs after MCs exposure including the liver, intestine, brain, kidney, lung, heart and reproductive system. In addition, some evidences on human poisoning and deaths associated with MCs exposure are presented. Finally, in order to protect human life against the health threats posed by MCs, this paper also suggests some directions for future research that can advance MCs control and minimize human exposure to MCs.

Tumor-promoting cyanotoxin microcystin-LR does not induce procarcinogenic events in adult human liver stem cells

HL1-hT1 cell line represents adult human liver stem cells (LSCs) immortalized with human telomerase reverse transcriptase. In this study, HL1-hT1 cells were found to express mesenchymal markers (vimentin, CD73, CD90/THY-1 and CD105) and an early hepatic endoderm marker FOXA2, while not expressing hepatic progenitor (HNF4A, LGR5, α-fetoprotein) or differentiated hepatocyte markers (albumin, transthyretin, connexin 32). In response to microcystin-LR (MC-LR), a time- and concentration-dependent formation of MC-positive protein bands in HL1-hT1 cells was observed. Cellular accumulation of MC-LR occurred most likely via mechanisms independent on organic anion transporting polypeptides (OATPs) or multidrug resistance (MDR) proteins, as indicated (a) by a gene expression analysis of 11 human OATP genes and 4 major MDR genes (MDR1/P-glycoprotein, MRP1, MRP2 and BCRP); (b) by non-significant effects of OATP or MDR1 inhibitors on MC-LR uptake. Accumulation of MC-positive protein bands in HL1-hT1 cells was associated neither with alterations of cell viability and growth, dysregulations of ERK1/2 and p38 kinases, reactive oxygen species formation, induction of double-stranded DNA breaks nor modulations of stress-inducible genes (ATF3, HSP5). It suggests that LSCs might have a selective, MDR1-independent, survival advantage and higher tolerance towards MC-induced cytotoxic, genotoxic or cancer-related events than differentiated adult hepatocytes, fetal hepatocyte or malignant liver cell lines. HL1-hT1 cells provide a valuable in vitro tool for studying effects of toxicants and pharmaceuticals on LSCs, whose important role in the development of chronic toxicities and liver diseases is being increasingly recognized.

Gene expression network regulated by DNA methylation and microRNA during microcystin-leucine arginine induced malignant transformation in human hepatocyte L02 cells

Microcystin (MC) is a cyclic heptapeptide compound which could lead to the development of hepatocellular carcinoma. However, the underlying epigenetic regulation mechanism is largely unknown. In this study, microcystin-LR (L: lysine, R: arginine, MC-LR) was used to induce the malignant transformation of human hepatocyte L02 cell line. The profile of gene expression, microRNA (miRNA) and DNA methylation were detected through high-throughput sequencing. Compared with control group, the expression of 826 genes and 187 miRNAs changed significantly in MC-LR treated group. DNA methylation sequencing analysis showed that 2592 CpG sites differentially methylated in promoter or the coding DNA sequence (CDS) of genes, while DNA methyltransferase 3 alpha (DNMT3a) and DNA methyltransferase 3 beta (DNMT3b) were dramatically up-regulated. Functional analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that significantly changed mRNAs and microRNAs were mainly involved in the formation of cancer, proliferation, invasion, migration and metabolism. MiRNA-mRNA network and mRNA-mRNA network analysis showed that hsa-miR-320a, hsa-miR-331-3p, hsa-miR-26a-5p, hsa-miR-196a-5p, hsa-miR-221-3p, coiled-coil domain containing 180 (CCDC180), melanoma antigen gene family member D1 (MAGED1), membrane spanning 4-domains A7 (MS4A7), hephaestin like 1 (HEPHL1), BH3 (Bcl-2 homology 3)-like motif containing, cell death inducer (BLID), matrix metallopeptidase 13 (MMP13), guanylate binding protein 5 (GBP5), adipogenesis regulatory factor (ADIRF), formin homology 2 domain containing 1 (FHDC1), protein kinase CAMP-dependent type II regulatory subunit beta (PRKAR2B), nodium leak channel, non-selective (NALCN), myosin light chain kinase 3 (MYLK3), epidermal growth factor receptor (EGFR) and zinc finger protein 704 (ZNF704) were key miRNAs and genes in the malignant transformation induced by MC-LR in L02 cells. Moreover, we found that expression of MYLK3, EGFR and ZNF704 were regulated by DNA methylation and miRNAs, and these genes affected the cell cycle and cell division. Our study suggested that characteristic gene alterations regulated by DNA methylation and miRNA could play an important role in environmental MC-LR induced hepatic carcinogenesis.

miR-149 in Human Cancer: A Systemic Review

MicroRNAs (miRNAs) are small noncoding RNAs that regulate post-transcriptional gene expression via binding to the 3'-untranslated region (3'-UTR) of targeted mRNAs. They are reported to play important roles in tumorigenesis and progression of various cancers. Among them, miR-149 was confirmed to be aberrantly regulated in various tumors. In this review, we provide a complex overview of miR-149, particularly summarize the critical roles of it in cancers and expect to lay the foundation for future works on this important microRNA.

MicroRNA expression profiling involved in MC-LR-induced hepatotoxicity using high-throughput sequencing analysis

Microcystin-LR (MC-LR), the most common microcystin (MC) present in water is known to pose a significant threat to human health especially hepatotoxicity. However, the specific molecular mechanisms underlying MC-LR-induced hepatic cellular damage still remain to be determined. MicroRNAs (miRNAs) are known to play key roles in cellular processes including development, cell proliferation and responsiveness to stress. Thus, this study aimed to examine, whether miRNAs were involved in the observed MC-LR-mediated liver damage using miRNA profiling of a human normal liver cell line HL7702 using high-throughput sequencing techniques. Protein phosphatase 2A (PP2A) activity, an established biomarker of microcystin toxicity, was determined 24 hr following treatment with the algal toxin to confirm responsiveness. Data demonstrated that MC-LR significantly inhibited PP2A activity in a concentration-dependent manner with inhibitory concentration (IC₅₀) value of 4.6 μM. Compared with control cells, treatment with MC-LR at concentrations of 1, 2.5, 5 or 10 μM significantly modified expression of levels of 3, 10, 9, and 99 miRNAs, respectively. Expression levels of miR-15b-3p were significantly increased in all 4 treatment groups, while miR-4521 expression levels were markedly reduced. In the case of miR-451a, 1, 5 or 10 μM also significantly lowered expression levels. However, a significant rise in miR-451a was noted in cells exposed to 2.5 μM toxin. The results obtained from miRNA differential expression levels were confirmed by real-time fluorescent quantitative PCR (qPCR). Gene Ontology (GO) enrichment analysis of hepatic cells demonstrated that miRNAs significantly altered were involved in systems development, metabolism, and protein binding. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis data showed that target genes of differentially expressed miRNAs in liver cells predominantly participated in mechanistic target of rapamycin kinase (mTOR), Ras, Ras-related protein 1 (Rap1), hypoxia inducible factor 1 (HIF-1), and cancer development. In summary, evidence indicates that MC-LR-induced hepatotoxicity may be associated with alterations in miRNAs. Evidence indicates that alterations in miR-451a, miR-4521 and miR-15b-3p may be involved in the observed MC-LR- induced hepatotoxicity.