miR-34a screened by miRNA profiling negatively regulates Wnt/β-catenin signaling pathway in Aflatoxin B1 induced hepatotoxicity

MicroRNAs: exploring their role in farm animal disease and mycotoxin challenges

MicroRNAs (miRNAs) serve as key regulators in gene expression and play a crucial role in immune responses, holding a significant promise for diagnosing and managing diseases in farm animals. This review article summarizes current research on the role of miRNAs in various farm animal diseases and mycotoxicosis, highlighting their potential as biomarkers and using them for mitigation strategies. Through an extensive literature review, we focused on the impact of miRNAs in the pathogenesis of several farm animal diseases, including viral and bacterial infections and mycotoxicosis. They regulate gene expression by inducing mRNA deadenylation, decay, or translational inhibition, significantly impacting cellular processes and protein synthesis. The research revealed specific miRNAs associated with the diseases; for instance, gga-miR-M4 is crucial in Marek's disease, and gga-miR-375 tumor-suppressing function in Avian Leukosis. In swine disease such as Porcine Respiratory and Reproductive Syndrome (PRRS) and swine influenza, miRNAs like miR-155 and miR-21-3p emerged as key regulatory factors. Additionally, our review highlighted the interaction between miRNAs and mycotoxins, suggesting miRNAs can be used as a biomarker for mycotoxin exposure. For example, alterations in miRNA expression, such as the dysregulation observed in response to Aflatoxin B1 (AFB1) in chickens, may indicate potential mechanisms for toxin-induced changes in lipid metabolism leading to liver damage. Our findings highlight miRNAs potential for early disease detection and intervention in farm animal disease management, potentially reducing significant economic losses in agriculture. With only a fraction of miRNAs functionally characterized in farm animals, this review underlines more focused research on specific miRNAs altered in distinct diseases, using advanced technologies like CRISPR-Cas9 screening, single-cell sequencing, and integrated multi-omics approaches. Identifying specific miRNA targets offers a novel pathway for early disease detection and the development of mitigation strategies against mycotoxin exposure in farm animals.

Allium sativum L. var. Voghiera Reduces Aflatoxin B1 Bioaccessibility and Cytotoxicity In Vitro

The present work focuses on the evaluation of AFB1's bioaccessibility and cytotoxicity in vitro using bread (naturally contaminated) enriched or not enriched with fresh Voghiera garlic (2%). Two different experiments were carried out: experiment 1 (E1), with low-AFB1-concentration breads (1.6-1.7 mg/kg); and experiment 2 (E2), with high-AFB1-concentration breads (96.4-102.7 mg/kg). Eight breads were prepared, four for E1 (experiment 1) and another four for E2 (experiment 2), with each experiment having a control group (C), a garlic-enriched group (2%) (G), an AFB1 group (A), and an AFB1 + garlic group (A + G). Simulated digestion was performed on each type of bread, and gastric and intestinal digests were obtained. AFB1 content in flours, baked bread, and gastric and intestinal digests was measured by High-Performance Liquid Chromatography coupled to Fluorescence Detection. The results demonstrate dose-dependent AFB1 bioaccessibility and that the presence of garlic contributed to its reduction in both doses (7-8%). Moreover, garlic's presence in AFB1-contaminated bread increased cell viability (9-18%) in differentiated Caco-2 cells and mitigated the arrest of S and G2/M phases provoked by AFB1 on Jurkat T cells and reduced apoptosis/necrosis, cellular reactive oxygen species (ROS), and mitochondrial ROS by 16%, 71%, and 24% respectively. The inclusion of garlic as a functional ingredient helped relieve the presence and effects of AFB1.

Pancreatic Neuroendocrine Tumors: Signaling Pathways and Epigenetic Regulation

Pancreatic neuroendocrine tumors (PNETs) are characterized by dysregulated signaling pathways that are crucial for tumor formation and progression. The efficacy of traditional therapies is limited, particularly in the treatment of PNETs at an advanced stage. Epigenetic alterations profoundly impact the activity of signaling pathways in cancer development, offering potential opportunities for drug development. There is currently a lack of extensive research on epigenetic regulation in PNETs. To fill this gap, we first summarize major signaling events that are involved in PNET development. Then, we discuss the epigenetic regulation of these signaling pathways in the context of both PNETs and commonly occurring-and therefore more extensively studied-malignancies. Finally, we will offer a perspective on the future research direction of the PNET epigenome and its potential applications in patient care.

Infectious Agents Induce Wnt/β-Catenin Pathway Deregulation in Primary Liver Cancers

Interaction between infectious agents and liver tissue, as well as repeated and extreme biological events beyond adaptive capacities, may result in pathological conditions predisposing people to development of primary liver cancers (PLCs). In adults, PLCs mainly comprise hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA). Various infectious agents in the hepatic microenvironment can destabilize normal liver cell functions by modulating the Wnt/β-catenin pathway components. Among them, hepatotropic viruses B, C, and D are involved in Wnt/β-catenin signaling dysregulation. Other microbial agents, including oncogenic viruses such as Epstein-Barr virus (EBV) and human papilloma virus (HPV), bacteria, e.g., Mycoplasma hyorhinis and Salmonella Typhi, the protozoan parasite Toxoplasma gondii, the fungus Aspergillus flavus, and liver flukes such as Clonorchissinensis or Opisthorchis viverrini, may induce malignant transformation in hepatocytes or in target cells of the biliary tract through aberrant Wnt signaling activation. This review focuses on new insights into infectious agents implicated in the deregulation of Wnt signaling and PLC development. Since the Wnt/β-catenin pathway is a driver of cancer following viral and bacterial infections, molecules inhibiting the complex axis of Wnt signaling could represent novel therapeutic approaches in PLC treatment.

Role of epigenetics in mycotoxin toxicity: a review

Mycotoxins can induce cell cycle disorders, cell proliferation, oxidative stress, and apoptosis through pathways such as those associated with MAPK, JAK2/STAT3, and Bcl-w/caspase-3, and cause reproductive toxicity, immunotoxicity, and genotoxicity. Previous studies have explored the toxicity mechanism of mycotoxins from the levels of DNA, RNA, and proteins, and proved that mycotoxins have epigenetic toxicity. To explore the toxic effects and mechanisms of these changes in mycotoxins, this paper summarizes the changes in DNA methylation, non-coding RNA, RNA and histone modification induced by several common mycotoxins (zearalenone, aflatoxin B1, ochratoxin A, deoxynivalenol, T-2 toxin, etc.) based on epigenetic studies. In addition, the roles of mycotoxin-induced epigenetic toxicity in germ cell maturation, embryonic development, and carcinogenesis are highlighted. In summary, this review provides theoretical support for a better understanding of the regulatory mechanism of mycotoxin epigenotoxicity and the diagnosis and treatment of diseases.

Comparative transcriptome analysis of brain and gonad reveals reproduction-related miRNAs in the giant prawn, Macrobrachium rosenbergii

Macrobrachium rosenbergii (M. rosenbergii), as a species of common prawn, is a delicacy that is consumed all over the world. By interacting with the target gene 3′-untranslated region (3'-UTR), microRNAs (miRNAs) regulate its expression and ultimately participate in the regulation of reproductive development. However, research focusing on miRNA regulation during gonadal development in M. rosenbergii received very little attention. To explore the association between miRNA and reproduction, we performed RNA sequencing (RNA-seq) on brain and gonad organs in male and female M. rosenbergii. A total of 494 miRNAs were obtained in RNA-seq, including 31 and 59 differentially expressed (DE) miRNAs in the brain and gonads, respectively. Furthermore, 9 DE miRNAs were randomly selected from the brain and gonads, and qRT-PCR was conducted to validate the results of RNA-seq. Interestingly, dpu-miR-133 was found to be substantially expressed in the male brain and testis but poorly expressed in the female brain, ovary, and other organs. Analysis of dpu-miR-133 by Targetscan and MiRanda predicted to target 5-HT1. Furthermore, the dual-luciferase reporter assay manifested that dpu-miR-133 can combine with 5-HT1. Overall, our research work provides basic data for further study on the miRNA-mediated regulation of brain, gonad, and reproductive development of study M. rosenbergii.

Effect of bone marrow mesenchymal stem cells-derived exosomes on diabetes-induced retinal injury: Implication of Wnt/ b-catenin signaling pathway

BACKGROUND

Diabetic retinopathy (DR) is a serious microvascular complication of diabetes mellitus. Mesenchymal stem cells are currently studied as therapeutic strategy for management of DR. Exosomes, considered as a promising cell-free therapy option, display biological functions similar to those of their parent cells. In retinal development, Wnt/b-catenin signaling provides key cues for functional progression. The present study aimed to evaluate the potential efficacy of bone marrow-derived mesenchymal stem cell-derived exosomes (BM-MSCs-Ex) in diabetes-induced retinal injury via modulation of the Wnt/ b-catenin signaling pathway.

METHODS

Eighty-one rats were allocated into 6 groups (control, DR, DR + DKK1, DR + exosomes, DR + Wnt3a and DR + exosomes+Wnt3a). Evaluation of each group was via histopathological examination, assessment of gene and/or protein expression concerned with oxidative stress (SOD1, SOD2, Nox2, Nox4, iNOS), inflammation (TNF-α, ICAM-1, NF-κB) and angiogenesis (VEGF, VE-cadherin).

RESULTS

Results demonstrated that exosomes blocked the wnt/b-catenin pathway in diabetic retina concomitant with significant reduction of features of DR as shown by downregulation of retinal oxidants, upregulation of antioxidant enzymes, suppression of retinal inflammatory and angiogenic markers. These results were further confirmed by histopathological results, fundus examination and optical coherence tomography. Additionally, exosomes ameliorative effects abrogated wnt3a-triggered retinal injury in DR.

CONCLUSION

Collectively, these data demonstrated that exosomes ameliorated diabetes-induced retinal injury via suppressing Wnt/ b-catenin signaling with subsequent reduction of oxidative stress, inflammation and angiogenesis.

Research progress in toxicological effects and mechanism of aflatoxin B1 toxin

Fungal contamination of animal feed can severely affect the health of farm animals, and result in considerable economic losses. Certain filamentous fungi or molds produce toxic secondary metabolites known as mycotoxins, of which aflatoxins (AFTs) are considered the most critical dietary risk factor for both humans and animals. AFTs are ubiquitous in the environment, soil, and food crops, and aflatoxin B₁(AFB₁) has been identified by the World Health Organization (WHO) as one of the most potent natural group 1A carcinogen. We reviewed the literature on the toxic effects of AFB₁ in humans and animals along with its toxicokinetic properties. The damage induced by AFB₁ in cells and tissues is mainly achieved through cell cycle arrest and inhibition of cell proliferation, and the induction of apoptosis, oxidative stress, endoplasmic reticulum (ER) stress and autophagy. In addition, numerous coding genes and non-coding RNAs have been identified that regulate AFB₁ toxicity. This review is a summary of the current research on the complexity of AFB₁ toxicity, and provides insights into the molecular mechanisms as well as the phenotypic characteristics.

Multi-Omics Reveal Additive Cytotoxicity Effects of Aflatoxin B1 and Aflatoxin M1 toward Intestinal NCM460 Cells

Aflatoxin B1 (AFB1) is a common crop contaminant, while aflatoxin M1 (AFM1) is implicated in milk safety. Humans are likely to be simultaneously exposed to AFB1 and AFM1; however, studies on the combined interactive effects of AFB1 and AFM1 are lacking. To fill this knowledge gap, transcriptomic, proteomic, and microRNA (miRNA)-sequencing approaches were used to investigate the toxic mechanisms underpinning combined AFB1 and AFM1 actions in vitro. Exposure to AFB1 (1.25–20 μM) and AFM1 (5–20 μM) for 48 h significantly decreased cell viability in the intestinal cell line, NCM460. Multi-omics analyses demonstrated that additive toxic effects were induced by combined AFB1 (2.5 μM) and AFM1 (2.5 μM) in NCM460 cells and were associated with p53 signaling pathway, a common pathway enriched by differentially expressed mRNAs/proteins/miRNAs. Specifically, based on p53 signaling, cross-omics showed that AFB1 and AFM1 reduced NCM460 cell viability via the hsa-miR-628-3p- and hsa-miR-217-5p-mediated regulation of cell surface death receptor (FAS), and also the hsa-miR-11-y-mediated regulation of cyclin dependent kinase 2 (CDK2). We provide new insights on biomarkers which reflect the cytotoxic effects of combined AFB1 and AFM1 toxicity.

MicroRNA regulates the toxicological mechanism of four mycotoxins in vivo and in vitro

Mycotoxins can cause body poisoning and induce carcinogenesis, often with a high mortality rate. Therefore, it is of great significance to seek new targets that indicate mycotoxin activity and to diagnose and intervene in mycotoxin-induced diseases in their early stages. MicroRNAs (miRNAs) are physiological regulators whose dysregulation is closely related to the development of diseases. They are thus important markers for the occurrence and development of diseases. In this review, consideration is given to the toxicological mechanisms associated with four major mycotoxins (ochratoxin A, aflatoxin B1, deoxynivalenol, and zearalenone). The roles that miRNAs play in these mechanisms and the interactions between them and their target genes are explained, and summarize the important role of histone modifications in their toxicity. As a result, the ways that miRNAs are regulated in the pathogenicity signaling pathways are revealed which highlights the roles played by miRNAs in preventing and controlling the harmful effects of the mycotoxins. It is hoped that this review will provide a theoretical basis for the prevention and control of the damage caused by these mycotoxins.

miR-520a-5p regulates Frizzled 9 expression and mediates effects of cigarette smoke and iloprost chemoprevention

Expression of Frizzled 9 (FZD9) is critical to the activity of the lung cancer chemoprevention agent and prostacyclin analogue, iloprost. FZD9 is required in lung epithelial cells for iloprost to activate peroxisome proliferator activated receptor gamma (PPARG) and related anti-tumor signaling. We aimed to investigate which miRNA regulate FZD9 in the context of cigarette smoke exposure and iloprost treatment. We found that miR-520a-5p binds the FZD9 3’UTR in lung cell lines and alters activity and expression of FZD9 downstream targets. Cigarette smoke condensate (CSC) increases expression of miR-520a-5p, while iloprost decreases expression. Cancer promoting effects of a miR-520a-5p mimic were rescued with iloprost treatment, and effects of cigarette smoke were partially rescued with a miR-520a-5p inhibitor. Here we confirm miR-520a-5p as a regulator of FZD9 activity and a mediator of CSC and iloprost effects in the lung. Targeting miR-520a-5p could be an approach to restoring FZD9 expression and improving response to iloprost lung cancer chemoprevention.

MicroRNA target-based network predicts androgen receptor-linked mycotoxin stress

Stress-responsive microRNAs (miRNAs) contribute to the regulation of cellular homeostasis or pathological processes, including carcinogenesis, by reprogramming target gene expression following human exposure to environmental or dietary xenobiotics. Herein, we predicted the targets of carcinogenic mycotoxin-responsive miRNAs and analyzed their association with disease and functionality. miRNA target-derived prediction indicated potent associations of oncogenic mycotoxin exposure with metabolism- or hormone-related diseases, including sex hormone-linked cancers. Mechanistically, the signaling network evaluation suggested androgen receptor (AR)-linked signaling as a common pivotal cluster associated with metabolism- or hormone-related tumorigenesis in response to aflatoxin B1 and ochratoxin A co-exposure. Particularly, high levels of AR and AR-linked genes for the retinol and xenobiotic metabolic enzymes were positively associated with attenuated disease biomarkers and good prognosis in patients with liver or kidney cancers. Moreover, AR-linked signaling was protective against OTA-induced genetic insults in human hepatocytes whereas it was positively involved in AFB1-induced genotoxic actions. Collectively, miRNA target network-based predictions provide novel clinical insights into the progression or intervention against malignant adverse outcomes of human exposure to environmental oncogenic insults.

Aflatoxin B1: metabolism, toxicology, and its involvement in oxidative stress and cancer development

Aflatoxins are a class of carcinogenic mycotoxins produced by Aspergillus fungi, which are widely distributed in nature. Aflatoxin B1 (AFB1) is the most toxic of these compounds and its metabolites have a variety of biological activities, including acute toxicity, teratogenicity, mutagenicity and carcinogenicity, which has been well-characterized to lead to the development of hepatocellular carcinoma (HCC) in humans and animals. This review focuses on the metabolism of AFB1, including epoxidation and DNA adduction, as it concerns the initiation of cancer and the underlying mechanisms. In addition to DNA adduction, inflammation and oxidative stress caused by AFB1 can also participate in the occurrence of cancer. Therefore, the main carcinogenic mechanism of AFB1 related ROS is summarized. This review also describes recent reports of AFB1 exposures in occupational settings. It is hoped that people will pay more attention to occupational health, in order to reduce the incidence of cancer caused by occupational exposure.

Exosomes mediated the delivery of ochratoxin A-induced cytotoxicity in HEK293 cells

Ochratoxin A (OTA) is one of the mycotoxins, which widely pollutes food systems and seriously threatens human health. OTA's target organ is the kidney. Exosome, as one of the extracellular vesicles, could be secreted by all kinds of cells. It contains different proteins, nucleic acid, and lipid, which are decided by their donor cells and could be uptake by the recipient cells, release their contents, and affect the recipient cell's life activity. In this study, a 24 h-treatment with 5 μM OTA was found to significantly reduce the cell viability of HEK293 cells and meanwhile to provide a sufficient quantity of exosomes, thus this concentration and time were selected for subsequent experiments. In addition, exosomes extracted by ultracentrifugation had higher purity, fewer impurities, and uniform morphology than that by the ExoQuick-TC kit. Furthermore, these exosomes increased ROS levels and decreased mitochondrial membrane potential in HEK293 cells. By RNA-seq, the cytotoxicity mechanisms induced by OTA-treated HEK293 cell-derived exosomes (EXO-OTA) and OTA were mainly the metabolism of proteins and the cell cycle respectively. Also, it proved that exosomes deliver partial OTA-induced cytotoxicity.

Transcription Factors and Methylation Drive Prognostic miRNA Dysregulation in Hepatocellular Carcinoma

Many dysregulated microRNAs (miRNAs) have been suggested to serve as oncogenes or tumor suppressors to act as diagnostic and prognostic factors for HCC patients. However, the dysregulated mechanisms of miRNAs in HCC remain largely unknown. Herein, we firstly identify 114 disordered mature miRNAs in HCC, 93 of them are caused by dysregulated transcription factors, and 10 of them are driven by the DNA methylation of their promoter regions. Secondly, we find that seven up-regulated miRNAs (miR-9-5p, miR-452-5p, miR-452-3p, miR-1180-3p, miR-4746-5p, miR-3677-3 and miR-4661-5p) can promote tumorigenesis via inhibiting multiple tumor suppressor genes participated in metabolism, which may act as oncogenes, and seven down-regulated miRNAs (miR-99-5p, miR-5589-5p, miR-5589-3p, miR-139-5p, miR-139-3p, miR-101-3p and miR-125b-5p) can suppress abnormal cell proliferation via suppressing a number of oncogenes involved in cancer-related pathways, which may serve as tumor suppressors. Thirdly, our findings reveal a mechanism that transcription factor and miRNA interplay can form various regulatory loops to synergistically control the occurrence and development of HCC. Finally, our results demonstrate that this key transcription factor FOXO1 can activate a certain number of tumor suppressor miRNAs to improve the survival of HCC patients, suggesting FOXO1 as an effective therapeutic target for HCC patients. Overall, our study not only reveals the dysregulated mechanisms of miRNAs in HCC, but provides several novel prognostic biomarkers and potential therapeutic targets for HCC patients.

Aflatoxin B1 interferes with embryonic liver development: Involvement of p53 signaling and apoptosis in zebrafish

Aflatoxin B₁ (AFB₁), a naturally occurring mycotoxin, is present in human placenta and cord blood. AFB₁ at concentrations found in contaminated food commodities (0.25 and 0.5 μM) did not alter the spontaneous movement, heart rate, hatchability, or morphology of embryonic zebrafish. However, around 86 % of 0.25 μM AFB₁-treated embryos had livers of reduced size, and AFB₁ disrupted the hepatocyte structures, according to histological analysis. Additionally, AFB₁ treatment that begins at any stage before 72 h post-fertilization (hpf) effectively reduced the size of embryonic livers. In hepatic areas, AFB₁ suppressed the expression of Hhex and Prox1, which are two critical transcriptional factors for initiating hepatoblast specification. KEGG analysis based on transcriptome profiling indicated that p53 signaling and apoptosis are the only observed pathways in AFB₁-treated embryos. AFB₁ at 0.5 μM significantly activated the expression of tp53, mdm2, puma, noxa, pidd1, and gadd45aa genes that are related to the p53 pathway and also that of baxa, casp 8 and casp 3a in the apoptotic process. TUNEL staining demonstrated that AFB₁ triggered the apoptosis of embryonic hepatocytes in a dose-dependent manner. These results indicate that the deficiency of both hhex and prox1 as well as hepatocyte apoptosis via the p53-Puma/Noxa-Bax axis may contribute to the embryonic liver shrinkage that is caused by AFB_1.

Chemoprotective Effects of Xanthohumol against the Carcinogenic Mycotoxin Aflatoxin B1

The present study addresses the chemoprotective effects of xanthohumol (XN), a prenylated flavonoid found in the female inflorescences (hops) of the plant Humulus lupulus L., against the carcinogenic food contaminant aflatoxin B1 (AFB1). The chemical reactions of XN and its derivatives (isoxanthohumol (IXN), 8-prenylnaringenin (8-PN), and 6-prenylnaringenin (6-PN)) with the AFB1 metabolite, aflatoxin B1 exo-8,9-epoxide (AFBO), were investigated in silico, by calculating activation free energies (ΔG^‡) at the Hartree–Fock level of theory in combination with the 6-311++G(d,p) basis set and two implicit solvation models. The chemoprotective effects of XN were investigated in vitro in the metabolically competent HepG2 cell line, analyzing its influence on AFB1-induced cytotoxicity using the MTS assay, genotoxicity using the comet and γH2AX assays, and cell cycle modulation using flow cytometry. Our results show that the ΔG^‡ required for the reactions of XN and its derivatives with AFBO are comparable to the ΔG^‡ required for the reaction of AFBO with guanine, indicating that XN, IXN, 8-PN, and 6-PN could act as scavengers of AFBO, preventing DNA adduct formation and DNA damage induction. This was also reflected in the results from the in vitro experiments, where a reduction in AFB1-induced cytotoxicity and DNA single-strand and double-strand breaks was observed in cells exposed to combinations of AFB1 and XN, highlighting the chemoprotective effects of this phytochemical.

Multidimensional analysis of the epigenetic alterations in toxicities induced by mycotoxins

Mycotoxins contaminate all types of food and feed, threatening human and animal health through food chain accumulation, producing various toxic effects. Increasing attention is being focused on the molecular mechanism of mycotoxin-induced toxicity in all kinds of in vivo and in vitro models. Epigenetic alterations, including DNA methylation, non-coding RNAs (ncRNAs), and protein post-translational modifications (PTMs), were identified as being involved in various types of mycotoxin-induced toxicity. In this review, the emphasis was on summarizing the epigenetic alterations induced by mycotoxin, including aflatoxin B1 (AFB1), ochratoxin A (OTA), zearalenone (ZEA), fumonisin B1 (FB1), and deoxynivalenol (DON). This review summarized and analyzed the roles of DNA methylation, ncRNAs, and protein PTMs after mycotoxin exposure based on recently published papers. Moreover, the main research methods and their deficiencies were determined, while some remedial suggestions are proposed. In summary, this review helps to understand better the epigenetic alterations induced by the non-genotoxic effects of mycotoxin.

Contamination of Aflatoxins Induces Severe Hepatotoxicity Through Multiple Mechanisms

Aflatoxins (AFs) are commonly contaminating mycotoxins in foods and medicinal materials. Since they were first discovered to cause “turkey X” disease in the United Kingdom in the early 1960s, the extreme toxicity of AFs in the human liver received serious attention. The liver is the major target organ where AFs are metabolized and converted into extremely toxic forms to engender hepatotoxicity. AFs influence mitochondrial respiratory function and destroy normal mitochondrial structure. AFs initiate damage to mitochondria and subsequent oxidative stress. AFs block cellular survival pathways, such as autophagy that eliminates impaired cellular structures and the antioxidant system that copes with oxidative stress, which may underlie their high toxicities. AFs induce cell death via intrinsic and extrinsic apoptosis pathways and influence the cell cycle and growth via microribonucleic acids (miRNAs). Furthermore, AFs induce the hepatic local inflammatory microenvironment to exacerbate hepatotoxicity via upregulation of NF-κB signaling pathway and inflammasome assembly in the presence of Kupffer cells (liver innate immunocytes). This review addresses the mechanisms of AFs-induced hepatotoxicity from various aspects and provides background knowledge to better understand AFs-related hepatoxic diseases.

MiR-26a regulates the expression of serum IGF-1 in patients with osteoporosis and its effect on proliferation and apoptosis of mouse chondrocytes

OBJECTIVES

To examine the effects of the regulation on IGF-1 by miR-26a on the serum of patients with osteoporosis (OP) and apoptosis and proliferation of chondrocytes of mice with OP.

METHODS

Totally 47 patients with OP treated in our hospital between July 2018 and November 2019 were selected as the research group, and 42 healthy individuals in physical examination over this period were selected as the control group. Serum was sampled from each participant in both groups, and miR-26a in the sampled serum was quantified and compared. In addition, chondrocytes were sampled from mice with OP. The changes of proliferation and apoptosis of the chondrocytes were analyzed via MTT and flow cytometry, and the levels of Caspase3, Caspase9, Bax, and Bcl-2 were quantified by western blot (WB) assay.

RESULTS

MiR-26a was expressed highly in the serum of patients with OP and chondrocytes of mice with OP, while IGF-1 was lowly expressed in them. According to the dual-luciferase reporter assay, there was a targeting correlation between miR-26a and IGF-1, and suppressing miR-26a significantly up-regulated the expression and protein level of IGF-1.

CONCLUSIONS

MiR-26a can serve as a biological marker for the diagnosis of OP, and it can suppress the proliferation of chondrocytes and promote their apoptosis by regulating IGF-1.

miR-155 influences cell-mediated immunity in Balb/c mice treated with aflatoxin M1

Aflatoxin M1 (AFM1) is a 4-hydroxylated metabolite of aflatoxin B1 (AFB1). It induces various toxicological effects including immunotoxicity. In the present study, we investigated the effects of AFM1 on immune system and its modulation by MicroRNA (miR)-155. AFM1 was administered intraperitoneally at doses of 25 and 50 µg/kg for 28 days to Balb/c mice and different immune system parameters were analyzed. The levels of miR-155 and targeted proteins were evaluated in isolated T cells from spleens of mice. Spleen weight was reduced in mice exposed to AFM1 compared to negative control. Proliferation of splenocytes in response to phytohemagglutinin-A was reduced in mice exposed to AFM1. IFN-γ was decreased in mice exposed to AFM1, whereas IL-10 was increased. Concentration of IL-4 did not change different in mice exposed to AFM1 compared to negative control. Exposure to AFM1 reduced the expression of miR-155. Significant upregulation of phosphatidylinositol-3, 4, 5-trisphosphate 5-phosphatase 1 (Ship1) and suppressor of cytokine signaling 1 (Socs1) was observed in isolated T cells from spleens of mice treated with AFM1, but the transcription factor Maf (c-MAF) was not affected. These results suggest that miR-155 and targeted proteins might be involved in the immunotoxicity observed in mice exposed to AFM1.

miR-574-5p Targets FOXN3 to Regulate the Invasion of Nasopharyngeal Carcinoma Cells via Wnt/β-Catenin Pathway

MicroRNAs (miR) are a class of non-coding endogenous RNA molecules that suppress the translation of protein-coding genes by destabilizing target mRNAs. The MiR-574-5p has been reported to be involved in the several types of cancer. However, the expression of miR-574-5p and its mechanism in nasopharyngeal carcinoma (NPC) remain unclear. We found that the expression level of miR-574-5p was significantly increased in the NPC cell lines. We further demonstrated that Forkhead box N3 (FOXN3) was a target gene of miR-574-5p. FOXN3 overexpression and inhibition reversed the promoting or suppressing effect, respectively, of NPC cell proliferation, migration and invasion caused by miR-574-5p. Furthermore, miR-574-5p enhanced the β-catenin and TCF4 protein expression by repressing FOXN3 expression, resulting in the activation of the Wnt/β-catenin signaling pathway, but the activity of the Wnt/β-catenin signaling pathway was inhibited by a miR-574-5p inhibitor or FOXN3 overexpression, which reversed the effect of miR-574-5p. Wound-healing and Transwell assays also showed that miR-574-5p promotes the cell migration and invasion of NPC cells, whereas the promoting effect of miR-574-5p was also reversed by a miR-574-5p inhibitor or FOXN3 overexpression. Collectively, these data suggested that miR-574-5p promotes NPC cell proliferation, migration, and invasion at least partly by targeting the FOXN3/Wnt/β-Catenin signaling pathway.

Aflatoxin B1 Induces Neurotoxicity through Reactive Oxygen Species Generation, DNA Damage, Apoptosis, and S-Phase Cell Cycle Arrest

Aflatoxin B1 (AFB₁) is a mycotoxin widely distributed in a variety of food commodities and exhibits strong toxicity toward multiple tissues and organs. However, little is known about its neurotoxicity and the associated mechanism. In this study, we observed that brain integrity was markedly damaged in mice after intragastric administration of AFB₁ (300 μg/kg/day for 30 days). The toxicity of AFB₁ on neuronal cells and the underlying mechanisms were then investigated in the neuroblastoma cell line IMR-32. A cell viability assay showed that the IC50 values of AFB₁ on IMR-32 cells were 6.18 μg/mL and 5.87 μg/mL after treatment for 24 h and 48 h, respectively. ROS levels in IMR-32 cells increased significantly in a time- and AFB₁ concentration-dependent manner, which was associated with the upregulation of NOX2, and downregulation of OXR1, SOD1, and SOD2. Substantial DNA damage associated with the downregulation of PARP1, BRCA2, and RAD51 was also observed. Furthermore, AFB₁ significantly induced S-phase arrest, which is associated with the upregulation of CDKN1A, CDKN2C, and CDKN2D. Finally, AFB₁ induced apoptosis involving CASP3 and BAX. Taken together, AFB₁ manifests a wide range of cytotoxicity on neuronal cells including ROS accumulation, DNA damage, S-phase arrest, and apoptosis-all of which are key factors for understanding the neurotoxicology of AFB₁.

Single-cell sequencing reveals novel mechanisms of Aflatoxin B1-induced hepatotoxicity in S phase-arrested L02 cells

Aflatoxin B1 (AFB1) is widely distributed in nature and is confirmed to be the most toxic of all the aflatoxins, whose predominant metabolism site is the liver. As a well-studied and vital mode of epigenetic modifications, aberrant methylation of the promoters in eukaryotic cells may cause the silence of essential genes, affecting their related transcriptional pathways and ultimately leading to the development of disease and cancers. This study investigated the mechanisms of AFB1-induced hepatotoxicity in S phase-arrested L02 cells using single-cell RNA-seq and single-cell reduced representation bisulfite sequencing (RRBS). AFB1 induced apoptosis and cell cycle S phase arrest, reduced mitochondrial membrane potential (ΔΨm), and increased reactive oxygen species (ROS) generation, as well as the DNA methylation level. Hepatotoxicity mechanism patterns induced by AFB1 in S phase-arrested L02 cells were revealed by combining single-cell RNA-seq with single-cell RRBS analysis, in which DNA methylation played a role via regulating the gonadotropin-releasing hormone receptor pathway, the Wnt signaling pathway, and the TGF-beta signaling pathway. Moreover, a novel strategy for precision toxicology exploration was obtained, including the selection of target cells, multi-group non-directional sequencing, and pathway analysis.

Analysis of miRNA-mRNA regulatory network revealed key genes induced by aflatoxin B1 exposure in primary human hepatocytes

Background

Aflatoxin B1 (AFB1) exposure is a crucial factor to initiate hepatocellular carcinoma (HCC). However, comprehensive microRNA (miRNA)‐message RNA (mRNA) regulatory network regarding AFB1‐associated HCC is still lacking. This work was aimed to identify miRNA‐mRNA network in primary human hepatocytes after AFB1 exposure.

Methods

A miRNA expression dataset GSE71540 obtained from the gene expression omnibus (GEO) was used to identify differentially expressed miRNAs (DEMs) after AFB1 exposure using GEO2R. Target genes of these DEMs were identified using TargetScan V_7.2, miRDB, PITA, miRanda, and miRTarBase. Gene ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed at Database for Annotation, Visualization and Integrated Discovery (DAVID). miRNA‐mRNA regulatory network was established by analyzing three enriched KEGG pathways significantly correlated with HCC onset and then visualized at CytoScape.

Results

In this work, nine upregulated and nine downregulated DEMs were identified. Functional enrichment analyses showed that these predicted target genes were significantly associated with cancer development. Analysis of three enriched pathways related to the onset of HCC identified 13 and nine target genes for upregulated DEMs and downregulated DEMs, respectively. Subsequently, the miRNA‐mRNA regulatory networks were constructed.

Conclusions

In conclusion, miRNA‐mRNA regulatory network was established, which will help to understand the mechanism underlying the AFB1‐induced onset of HCC.

Wnt/β-Catenin Signaling in Liver Cancers

Liver cancer is among the leading global healthcare issues associated with high morbidity and mortality. Liver cancer consists of hepatocellular carcinoma (HCC), cholangiocarcinoma (CCA), hepatoblastoma (HB), and several other rare tumors. Progression has been witnessed in understanding the interactions between etiological as well as environmental factors and the host in the development of liver cancers. However, the pathogenesis remains poorly understood, hampering the design of rational strategies aiding in preventing liver cancers. Accumulating evidence demonstrates that aberrant activation of the Wnt/β-catenin signaling pathway plays an important role in the initiation and progression of HCC, CCA, and HB. Targeting Wnt/β-catenin signaling potentiates a novel avenue for liver cancer treatment, which may benefit from the development of numerous small-molecule inhibitors and biologic agents in this field. In this review, we discuss the interaction between various etiological factors and components of Wnt/β-catenin signaling early in the precancerous lesion and the acquired mechanisms to further enhance Wnt/β-catenin signaling to promote robust cancer formation at later stages. Additionally, we shed light on current relevant inhibitors tested in liver cancers and provide future perspectives for preclinical and clinical liver cancer studies.

microRNA-374 inhibits proliferation and promotes apoptosis of mouse melanoma cells by inactivating the Wnt signalling pathway through its effect on tyrosinase

Melanoma is one of the most malignant skin tumours with constantly increasing incidence worldwide. Previous studies have demonstrated that microRNA‐374 (miR‐374) is a novel biomarker for cancer therapy. Therefore, this study explores whether miR‐374 targeting tyrosinase (TYR) affects melanoma and its underlying mechanism. We constructed subcutaneous melanoma models to carry out the following experiments. The cells were transfected with a series of miR‐374 mimics, miR‐374 inhibitors or siRNA against TYR. Dual luciferase reporter gene assay was used for the verification of the targeting relationship between miR‐374 and TYR. Reverse transcription quantitative polymerase chain reaction and western blot analysis were conducted to determine the expression of miR‐374, TYR, β‐catenin, B‐cell leukaemia 2 (Bcl‐2), Bcl‐2 associated X protein (Bax), Low‐density lipoprotein receptor‐related protein 6 (LRP6), Leucine‐rich repeat G protein‐coupled receptor 5 (LGR5) and CyclinD1. Cell proliferation, migration, invasion, cell cycle distribution and apoptosis were evaluated using cell counting kit‐8 assay, scratch test, transwell assay and flow cytometry respectively. TYR was proved as a putative target of miR‐374 as the evidenced by the result. It was observed that up‐regulated miR‐374 or down‐regulated TYR increased expression of Bax and decreased expressions of TYR, β‐catenin, LRP6, Bcl‐2, CyclinD1 and LGR5, along with diminished cell proliferation, migration, invasion and enhanced apoptosis. Meanwhile, cells with miR‐374 inhibitors showed an opposite trend. These findings indicated that up‐regulated miR‐374 could inhibit the expression of TYR to suppress cell proliferation, migration, invasion and promote cell apoptosis in melanoma cells by inhibiting the Wnt signalling pathway.

Modulation of miR-34a in curcumin-induced antiproliferation of prostate cancer cells

Curcumin is a phytochemical which exhibits significant inhibitory effect in multiple cancers including prostate cancer. MicroRNA-34a (miR-34a) was found to be a master tumor suppressor miRNA and regulated the growth of cancer cells. To date, however, the role of miR-34a in the anticancer action of curcumin against prostate cancer has been rarely reported. In the present study, we showed that curcumin altered the expression of cell cycle-related genes (cyclin D1, PCNA, and p21) and inhibited the proliferation of prostate cancer cells. Furthermore, we found that curcumin significantly upregulated the expression of miR-34a, along with the downregulated expression of β-catenin and c-myc in three prostate cancer cell lines. Inhibition of miR-34a activated β-catenin/c-myc axis, altered cell cycle-related genes expression and significantly suppressed the antiproliferation effect of curcumin in prostate cancer cells. Findings from this study revealed that miR-34a plays an important role in the antiproliferation effect of curcumin in prostate cancer.

Identification and profiling of microRNAs during gonadal development in the giant freshwater prawn Macrobrachium rosenbergii

As post-transcriptional regulators, microRNAs (miRNAs) play an important role in growth and reproductive processes. So far, there is limited information regarding crustacean miRNAs. To explore the potential role of miRNAs in the gonadal development of the prawn Macrobrachium rosenbergii, we constructed seven small RNA libraries from ovarian and testicular tissues at various stages using somatic tissue as the control. A total of 1,954 known and 129 novel miRNAs were retrieved. By comparing differentially expressed miRNAs (DEMs) between testes and ovaries, forty-one miRNAs were identified with sex-biased expression patterns, including 17 ovary-biased and 24 testis-biased patterns. Furthermore, the putative target genes of the sex-biased miRNAs, such as cyclin L1, mitogen-activated protein kinase 7 (MAPK 7), heat shock protein (HSP), and zinc finger protein, were significantly enriched in many reproduction-related pathways including the Gonadotropin-releasing hormone (GnRH) pathway, glycolysis, gluconeogenesis pathway, ovarian steroidogenesis, estrogen signaling pathway, MAPK pathway, Wnt pathway, and insulin signaling pathway, implicating potential regulatory roles of miRNAs in reproduction. These data aid in the further investigation of the mechanism of gonadal development and reproductive regulation mediated by miRNA in M. rosenbergii.

Epigenetic alterations caused by aflatoxin b1: a public health risk in the induction of hepatocellular carcinoma

Aflatoxin B1 (AFB1) is currently the most commonly studied mycotoxin due to its great toxicity, its distribution in a wide variety of foods such as grains and cereals and its involvement in the development of + (hepatocellular carcinoma; HCC). HCC is one of the main types of liver cancer, and has become a serious public health problem, due to its high incidence mainly in Southeast Asia and Africa. Studies show that AFB1 acts in synergy with other risk factors such as hepatitis B and C virus leading to the development of HCC through genetic and epigenetic modifications. The genetic modifications begin in the liver through the biomorphic AFB1, the AFB1-exo-8.9-Epoxy active, which interacts with DNA to form adducts of AFB1-DNA. These adducts induce mutation in codon 249, mediated by a transversion of G-T in the p53 tumor suppressor gene, causing HCC. Thus, this review provides an overview of the evidence for AFB1-induced epigenetic alterations and the potential mechanisms involved in the development of HCC, focusing on a critical analysis of the importance of severe legislation in the detection of aflatoxins.

MicroRNAs and their role in environmental chemical carcinogenesis

MicroRNAs (miRNAs) are a class of small, noncoding RNA species that play crucial roles across many biological processes and in the pathogenesis of major diseases, including cancer. Recent studies suggest that the expression of miRNA is altered by certain environmental chemicals, including metals, organic pollutants, cigarette smoke, pesticides and carcinogenic drugs. In addition, extensive studies have indicated the existence and importance of miRNA in different cancers, suggesting that cancer-related miRNAs could serve as potential markers for chemically induced cancers. The altered expression of miRNA was considered to be a vital pathogenic role in xenobiotic-induced cancer development. However, the significance of miRNA in the etiology of cancer and the exact mechanisms by which environmental factors alter miRNA expression remain relatively unexplored. Hence, understanding the interaction of miRNAs with environmental chemicals will provide important information on mechanisms underlying the pathogenesis of chemically induced cancers, and effectively diagnose and treat human cancers resulting from chronic or acute carcinogen exposure. This study presents the current evidence that the miRNA deregulation induced by various chemical carcinogens, different cancers caused by environmental carcinogens and the potentially related genes in the onset or progression of cancer. For each carcinogen, the specifically expressed miRNA may be considered as the early biomarkers of the cancer process. In this review, we also summarize various target genes of the altered miRNA, oncogenes or anti-oncogenes, and the existing evidence regarding the gene regulation mechanisms of cancer caused by environmentally induced miRNA alteration. The future perspective of miRNA may become attractive targets for the diagnosis and treatment of carcinogen-induced cancer.

Molecular signatures of cytotoxic effects in human embryonic kidney 293 cells treated with single and mixture of ochratoxin A and citrinin

Ochratoxin A (OTA) and citrinin (CTN) are important mycotoxins, which often coexist in food and feed stuff. In this study, individual and combinative cytotoxicity of OTA and CTN were tested in human embryonic kidney (HEK) 293 cells via MTT assay, and synergistic cytotoxic effects were found following co-treatment with OTA and CTN, manifested by significant accumulation of HEK293 cells in S and G2/M stages. Transcriptomic and sRNA sequencing were performed to explore molecular signatures mediating individual or combinative cytotoxicity. A total of 378 miRNAs were identified, among which 66 miRNAs targeting thousands of genes were differentially expressed in response to different treatments, and 120 differentially expressed genes (DEGs) were regulated by either individual or combinative treatments. Correlations between two representative miRNAs (hsa-miR-1-3p and hsa-miR-122-5p), and their target genes, programmed cell death 10 (PDCD10) and cyclin G1 (CCNG1), associated with apoptotic signaling and cell cycle were analyzed by luciferase assay system. Further, their expression patterns were validated by quantitative real-time PCR and western blot analysis, suggesting that both miRNA-target interactions might account for the mycotoxin-induced cell death. Taken together, these findings provide molecular evidences for synergistic cytotoxic effects of exposure to single and mixture of OTA and CTN in HEK293 cells.

Evaluation of Aflatoxin M1 Effects on the Metabolomic and Cytokinomic Profiling of a Hepatoblastoma Cell Line

Hepatoblastoma incidence has been associated with different environmental factors even if no data are reported about a correlation between aflatoxin exposure and hepatoblastoma initiation. Considering that hepatoblastoma develops in infants and children and aflatoxin M1 (AFM1), the aflatoxin B1 (AFB1) hydroxylated metabolite, can be present in mothers' milk and in marketed milk products, in this study we decided to test the effects of AFM1 on a hepatoblastoma cell line (HepG2). Firstly, we evaluated the effects of AFM1 on the cell viability, apoptosis, cell cycle, and metabolomic and cytokinomic profile of HepG2 cells after treatment. AFM1 induced: (1) a decrease of HepG2 cell viability, reaching IC50 at 9 µM; (2) the blocking of the cell cycle in the G0/G1 phase; (3) the decrease of formiate levels and incremented level of some amino acids and metabolites in HepG2 cells after treatment; and (4) the increase of the concentration of three pro-inflammatory cytokines, IL-6, IL-8, and TNF-α, and the decrease of the anti-inflammatory interleukin, IL-4. Our results show that AFM1 inhibited the growth of HepG2 cells, inducing both a modulation of the lipidic, glycolytic, and amino acid metabolism and an increase of the inflammatory status of these cells.

MiRNA-16 inhibited oral squamous carcinoma tumor growth in vitro and in vivo via suppressing Wnt/β-catenin signaling pathway

Background

Oral carcinoma, one of the most commonly diagnosed cancers, has a poor prognosis and low survival rate with treatment. In recent years, some studies reported the upregulation of miRNA-16 (miR-16) in the oral carcinoma, whereas some other studies confirmed the downregulation of miR-16. In the current study, we aimed to investigate the function of miR-16 in oral carcinoma.

Materials and methods

Cell proliferation assay was measured by MTT assay, quantitative real time polymerase chain reaction (qRT-PCR) was used to evaluate the expression of miR-16, and apoptosis was analyzed by flow cytometry. In addition, the expression of proteins was detected by Western blot. Moreover, xenograft tumor model was established to detect the effect of miR-16 in vivo.

Results

The results suggested that miR-16 was downregulated in the oral carcinoma tissues. Overexpression of miR-16 inhibited the growth and proliferation of oral squamous carcinoma cells (OSCCs) and induced apoptosis both in vitro and in vivo, which is due to the suppression of Wnt/β-catenin signaling pathway.

Conclusion

This study provides evidence that overexpression of miR-16 inhibits OSCC growth by regulating Wnt/β-catenin signaling. Our findings suggest that overexpression of miR-16 could be a potential approach for gene therapy of OSCC in future.

Aflatoxin B1 induced multiple epigenetic modulators in human epithelial cell lines

The compulsive and insidious secondary metabolite aflatoxin B₁, produced by the opportunistic fungi Aspergillus flavus, upholds a distinguished place in midst of the toxicants causing fatal hazards to humans. Aflatoxins alter the function of host cells by inducing multiple effects through genetic and non-genetic pathways. Epigenetic mechanisms drag major attention towards finding novel and new mechanisms involved in this process. Our present work intends to study the functional expression profile of multiple epigenetic regulators. AFB₁ modulates multiple epigenetic regulators like DNA methyltransferases (DMNTs), histones modifying enzymes and polycomb proteins. AFB₁ upregulates the expression of DNMTs at gene and protein level in a dose dependent manner. It reduced the histone acetyl transferase (HAT) activity significantly with a remarkable increase in histone deacetylase (HDAC) activity along with an induction in expression of HDACs gene and protein in a dose dependent manner. The gene and protein expression of polycomb repressor proteins B cell specific moloney murine leukemia virus integration site 1 (BMI-1) and enhancer of zeste homolog 2 (EZH2) was significantly over expressed with enhanced trimethylation of H3K27 and ubiquitination of H2AK119. In summary, our results show impact of aflatoxin B₁ on multiple epigenetic modulations known to be pivotal in oncogenic processes.

Validation of miRNA prognostic power in hepatocellular carcinoma using expression data of independent datasets

Multiple studies suggested using different miRNAs as biomarkers for prognosis of hepatocellular carcinoma (HCC). We aimed to assemble a miRNA expression database from independent datasets to enable an independent validation of previously published prognostic biomarkers of HCC. A miRNA expression database was established by searching the TCGA (RNA-seq) and GEO (microarray) repositories to identify miRNA datasets with available expression and clinical data. A PubMed search was performed to identify prognostic miRNAs for HCC. We performed a uni- and multivariate Cox regression analysis to validate the prognostic significance of these miRNAs. The Limma R package was applied to compare the expression of miRNAs between tumor and normal tissues. We uncovered 214 publications containing 223 miRNAs identified as potential prognostic biomarkers for HCC. In the survival analysis, the expression levels of 55 and 84 miRNAs were significantly correlated with overall survival in RNA-seq and gene chip datasets, respectively. The most significant miRNAs were hsa-miR-149, hsa-miR-139, and hsa-miR-3677 in the RNA-seq and hsa-miR-146b-3p, hsa-miR-584, and hsa-miR-31 in the microarray dataset. Of the 223 miRNAs studied, the expression was significantly altered in 102 miRNAs in tumors compared to normal liver tissues. In summary, we set up an integrated miRNA expression database and validated prognostic miRNAs in HCC.

Aflatoxin B1 and M1: Biological Properties and Their Involvement in Cancer Development

Aflatoxins are fungal metabolites found in feeds and foods. When the ruminants eat feedstuffs containing Aflatoxin B1 (AFB1), this toxin is metabolized and Aflatoxin M1 (AFM1) is excreted in milk. International Agency for Research on Cancer (IARC) classified AFB1 and AFM1 as human carcinogens belonging to Group 1 and Group 2B, respectively, with the formation of DNA adducts. In the last years, some epidemiological studies were conducted on cancer patients aimed to evaluate the effects of AFB1 and AFM1 exposure on cancer cells in order to verify the correlation between toxin exposure and cancer cell proliferation and invasion. In this review, we summarize the activation pathways of AFB1 and AFM1 and the data already reported in literature about their correlation with cancer development and progression. Moreover, considering that few data are still reported about what genes/proteins/miRNAs can be used as damage markers due to AFB1 and AFM1 exposure, we performed a bioinformatic analysis based on interaction network and miRNA predictions to identify a panel of genes/proteins/miRNAs that can be used as targets in further studies for evaluating the effects of the damages induced by AFB1 and AFM1 and their capacity to induce cancer initiation.

The molecular mechanism of cell cycle arrest in the Bursa of Fabricius in chick exposed to Aflatoxin B 1

Aflatoxin B₁ shows potent hepatotoxic, carcinogenic, genotoxic, immunotoxic potential in humans and many species of animals. The aim of this study was to clarify the underlying mechanism of G₀G₁ phase and G₂M phase arrest of cell cycle in the bursa of Fabricius in broilers exposed to dietary AFB₁. 144 one-day-old healthy Cobb broilers were randomly divided into two groups and fed on control diet and 0.6 mg·Kg⁻¹ AFB₁ diet for 3 weeks. Histological observation showed that AFB₁ induced the increase of nuclear debris and vacuoles in lymphoid follicle of BF. Results of flow cytometry studies showed that bursal cells arrested in G₂M phase at 7 days of age and blocked in G₀G₁ phase at 14 and 21 days of age following exposure to AFB₁. The qRT-PCR analysis indicated that cell cycle arrested in G₂M phase via ATM-Chk2-cdc25-cyclin B/cdc2 pathway, and blocked in G₀G₁ phase through ATM-Chk2-cdc25-cyclin D/CDK6 pathway and ATM-Chk2-p21-cyclin D/CDK6 route. In a word, our results provided new insights that AFB₁ diet induced G₂M and G₀G₁ phase blockage of BF cells in different periods, and different pathways were activated in different arrested cell cycle phase.

Comparative analysis of miRNA expression profiles in transgenic and non-transgenic rice using miRNA-Seq

Safety assessment for genetically modified organisms (GMOs) is required before their release. To date, miRNAs that play important roles in eukaryotic gene regulation have not been considered in the current assessment system. In this study, we identified 6 independent Bt and EPSPS GM rice lines using PCR and immune strip. We analyzed the expression levels of Cry1Ac and EPSPS using quantitative real-time PCR and western blot. Further, miRNAs from the developing seeds of the 6 GM rice lines and the wild-type line were investigated using deep sequencing and bioinformatic approaches. Although these GM lines have different types of integration sites, copy numbers, and levels of gene expression, 21 differentially expressed miRNAs have been found compared to wild type. There is no correlation between transgenic protein expression level and the quantity of differentially expressed miRNAs. This study provides useful data about the miRNA composition of GM plants, and it might be helpful for future risk assessments of miRNA-based GM plants.

Analysis of microarrays of miR-34a and its identification of prospective target gene signature in hepatocellular carcinoma

BACKGROUND

Currently, some studies have demonstrated that miR-34a could serve as a suppressor of several cancers including hepatocellular carcinoma (HCC). Previously, we discovered that miR-34a was downregulated in HCC and involved in the tumorigenesis and progression of HCC; however, the mechanism remains unclear. The purpose of this study was to estimate the expression of miR-34a in HCC by applying the microarray profiles and analyzing the predicted targets of miR-34a and their related biological pathways of HCC.

METHODS

Gene expression omnibus (GEO) datasets were conducted to identify the difference of miR-34a expression between HCC and corresponding normal tissues and to explore its relationship with HCC clinicopathologic features. The natural language processing (NLP), gene ontology (GO), pathway and network analyses were performed to analyze the genes associated with the carcinogenesis and progression of HCC and the targets of miR-34a predicted in silico. In addition, the integrative analysis was performed to explore the targets of miR-34a which were also relevant to HCC.

RESULTS

The analysis of GEO datasets demonstrated that miR-34a was downregulated in HCC tissues, and no heterogeneity was observed (Std. Mean Difference(SMD) = 0.63, 95% confidence intervals(95%CI):[0.38, 0.88], P < 0.00001; P_{heterogeneity} = 0.08 I² = 41%). However, no association was found between the expression value of miR-34a and any clinicopathologic characteristics. In the NLP analysis of HCC, we obtained 25 significant HCC-associated signaling pathways. Besides, we explored 1000 miR-34a-related genes and 5 significant signaling pathways in which CCND1 and Bcl-2 served as necessary hub genes. In the integrative analysis, we found 61 hub genes and 5 significant pathways, including cell cycle, cytokine-cytokine receptor interaction, notching pathway, p53 pathway and focal adhesion, which proposed the relevant functions of miR-34a in HCC.

CONCLUSION

Our results may lead researchers to understand the molecular mechanism of miR-34a in the diagnosis, prognosis and therapy of HCC. Therefore, the interaction between miR-34a and its targets may promise better prediction and treatment for HCC. And the experiments in vivo and vitro will be conducted by our group to identify the specific mechanism of miR-34a in the progress and deterioration of HCC.

Phenanthrene-Induced Apoptosis and Its Underlying Mechanism

Phenanthrene (Phe) is one of the most abundant low-molecular-weight polycyclic aromatic hydrocarbons (PAHs). Widespread human and aquatic organism exposure to Phe has been reported, but the toxic effects of Phe and potential mechanisms are unclear. We focused on the chronic hepatotoxicity of Phe in adult Chinese rare minnows (Gobiocypris rarus) and the underlying mechanisms. The chronic effects of exposing Chinese rare minnows to 8.9, 82.3, or 510.0 μg/L Phe for 30 days were examined by histopathological observation, TUNEL assays, caspase activity assays, and gene expression profiles. The liver lesion frequency and hepatocyte apoptosis were increased in Phe-exposed groups. Caspase 9 and caspase 3 enzyme activity in liver tissues was markedly increased. The expression of miR-17/92 cluster members was significantly increased in the 82.3 and 510.0 μg/L groups. Moreover, the response of primary hepatocytes indicated a significant decrease in the mitochondrial membrane potential (MMP) after a 48 h exposure to Phe. Interestingly, miR-18a was significantly decreased in primary hepatocytes in all treatments. Moreover, molecular docking indicated that Phe might have the same binding domain as pri-miR-18a, forming pi-pi and pi-σ interactions with heterogeneous nuclear ribonucleoprotein (hnRNP) A1. Given the above, Phe caused liver lesions and induced hepatocyte apoptosis through the intrinsic apoptosis pathway, and the interaction of Phe with hnRNP A1 contributes to the suppression of miR-18a expression and hepatocyte apoptosis.

The crosstalk between microRNAs and the Wnt/β-catenin signaling pathway in cancer

Mounting evidence has indicated microRNA (miR) dysregulation and the Wnt/β-catenin signaling pathway jointly drive carcinogenesis, cancer metastasis, and drug-resistance. The current review will focus on the role of the crosstalk between miRs and the Wnt/β-catenin signaling pathway in cancer development. MiRs were found to activate or inhibit the canonical Wnt pathway at various steps. On the other hand, Wnt activation increases expression of miR by directly binding to its promoter and activating transcription. Moreover, there are mutual feedback loops between some miRs and the Wnt/β-catenin signaling pathway. Clinical trials of miR-based therapeutic agents are investigated for solid and hematological tumors, however, challenges concerning low bioavailability and possible side effects must be overcome before the final clinical application. This review will describe current understanding of miR crosstalk with the Wnt/β-catenin signaling cascade. Better understanding of the regulatory network will provide insight into miR-based therapeutic development.

Profound changes in miRNA expression during cancer initiation by aflatoxin B1 and their abrogation by the chemopreventive triterpenoid CDDO-Im

Aflatoxin B₁ (AFB₁ ) is a potent human and animal hepatocarcinogen. To investigate the effects of aflatoxin on miRNA expression during the initiation phase of carcinogenesis, next-generation sequencing was used to analyze liver tissues from F344 rats exposed to 200 μg/kg per day AFB₁ for 4 week. A panel of miRNAs was identified that was upregulated with AFB₁ treatment compared to controls: rno-miR-434-3p, rno-miR-411-5p, rno-miR-221-3p, rno-miR-127-3p, rno-miR-205, rno-miR-429, rno-miR-34a-5p, rno-miR-181c-3p, rno-miR-200b-3p, and rno-miR-541-5p. Analysis of rat livers exposed to AFB₁ plus the chemopreventive triterpenoid CDDO-Im revealed a striking abrogation of this upregulation. These changes were validated by real-time PCR. We also explored the temporal variation in expression of the candidate miRNAs during the 4-week dosing period. Most of the candidate miRNAs were upregulated at week 1 and increased for the duration of AFB₁ dosing over the 4-week period. Treatment with CDDO-Im ameliorated these effects at all time points. All candidate miRNAs were detectable in serum from aflatoxin treated animals; however, there was no significant difference in expression for 7 of the 11 miRNAs examined. Exposure to AFB₁ upregulated miR-122-5p (fivefold), 34a-5p (13-fold), and 181c-3p (170-fold) compared with controls. The findings from this study give insight into epigenetic changes induced by aflatoxin taking place during the initial step of carcinogenesis.

Aflatoxin B1-induced epigenetic alterations: An overview

Aflatoxin B1 (AFB1) is widely distributed in nature, especially in a variety of food commodities. It is confirmed to be the most toxic of all the aflatoxins. The toxicity of AFB1 has been well investigated, and it may result in severe health problems including carcinogenesis, mutagenesis, growth retardation, and immune suppression. Epigenetic modifications including DNA methylation, histone modifications and regulation of non-coding RNA play an important role in AFB1-induced disease and carcinogenesis. To better understand the evidence for AFB1-induced epigenetic alterations and the potential mechanisms of the toxicity of AFB1, we conducted a review of published studies of AFB1-induced epigenetic alterations.