Nano nickel oxide promotes epithelial-mesenchymal transition through transforming growth factor β1/smads signaling pathway in A549 cells

Investigating the impact of different routes of nano and micro nickel oxide administration on rat kidney architecture, apoptosis markers, oxidative stress, and histopathology

Although the production and use of nickel oxide nanoparticles (NiONP) are widespread, environmental and public health problems are associated with it. The kidney is the primary organ in excretion and is among the target organs in nanoparticle toxicity. This study aimed to compare the renal toxicity of nickel oxide (NiO) microparticles and nickel oxide nanoparticles by different routes of administration, such as oral, intraperitoneal (IP), and intravenous (IV). Seven groups were formed, with 42 male rats and six animals in each group. NiO oral (150 mg/kg), NiO IP (20 mg/kg), NiO IV (1 mg/kg), NiONP oral (150 mg/kg), NiONP IP (20 mg/kg), and NiONP IV (1 mg/kg) was administered for 21 days. After NiO and NiONP administration, a decrease in antioxidant activities and an increase in lipid peroxidation occurred in the kidney tissue of rats. Increased kidney urea, uric acid, and creatinine levels were observed. Inhibition of acetylcholinesterase activity and an increase in interleukin 1 beta were detected. Apoptotic markers, Bax, caspase-3, and p53 up-regulation and Bcl-2 down-regulation were observed. In addition, histopathological changes occurred in the kidney tissue. In general, it was observed that nickel oxide microparticles and nickel oxide nanoparticles cause inflammation by causing oxidative stress in the kidney tissue, and NiONP IV administration is more effective in renal toxicity.

Suspended particulate matter promotes epithelial-to-mesenchymal transition in alveolar epithelial cells via TGF-β1-mediated ROS/IL-8/SMAD3 axis

Epidemiological evidence presents that dust storms are related to respiratory diseases, such as pulmonary fibrosis (PF). However, the precise underlying mechanisms of SPM-elicited adverse effects still need to be investigated. Epithelial-mesenchymal transition (EMT) process is a characteristic of PF. We discussed whether suspended particulate matter (SPM) is involved in EMT induction via transforming growth factor-β1 (TGF-β1). In this study, a detailed elemental analysis (55 elements), particle size, and morphology were determined. To investigate the toxicity of SPM, an MTT test was performed to detect cell viability. Next, A549 cells were exposed to selected concentrations of SPM (20 and 40 µg/mL) for single and repeated exposures. The DCFH-DA assay showed that exposure to SPM could produce reactive oxygen species (ROS). The ELISA assay demonstrated increased levels of interleukin-8 (IL-8) and TGF-β1 in the supernatant. Western blot was used to detect the expression of proteins associated with EMT and the SMAD3-dependent pathway. Results of western blot demonstrated that E-cadherin was reduced, whereas p-SMAD3, vimentin, and α-smooth muscle actin were elevated. Our findings indicated that SPM triggered EMT by induction of oxidative stress, inflammation, and the TGF-β1/SMAD3 pathway activation.

The pulmonary effects of nickel-containing nanoparticles: Cytotoxicity, genotoxicity, carcinogenicity, and their underlying mechanisms

With the exponential growth of the nanotechnology field, the global nanotechnology market is on an upward track with fast-growing jobs. Nickel (Ni)-containing nanoparticles (NPs), an important class of transition metal nanoparticles, have been extensively used in industrial and biomedical fields due to their unique nanostructural, physical, and chemical properties. Millions of people have been/are going to be exposed to Ni-containing NPs in occupational and non-occupational settings. Therefore, there are increasing concerns over the hazardous effects of Ni-containing NPs on health and the environment. The respiratory tract is a major portal of entry for Ni-containing NPs; thus, the adverse effects of Ni-containing NPs on the respiratory system, especially the lungs, have been a focus of scientific study. This review summarized previous studies, published before December 1, 2023, on cytotoxic, genotoxic, and carcinogenic effects of Ni-containing NPs on humans, lung cells in vitro, and rodent lungs in vivo, and the potential underlying mechanisms were also included. In addition, whether these adverse effects were induced by NPs themselves or Ni ions released from the NPs was also discussed. The extra-pulmonary effects of Ni-containing NPs were briefly mentioned. This review will provide us with a comprehensive view of the pulmonary effects of Ni-containing NPs and their underlying mechanisms, which will shed light on our future studies, including the urgency and necessity to produce engineering Ni-containing NPs with controlled and reduced toxicity, and also provide the scientific basis for developing nanoparticle exposure limits and policies.

A transcriptomics-based investigation of the mechanism of pulmonary fibrosis induced by nickel oxide nanoparticles

Nickel oxide nanoparticles (NiONPs) are an emerging nanomaterial, which poses a huge threat to the health of workplace population. Nanoparticles induce pulmonary fibrosis, and its mechanisms are associated with noncoding RNAs (ncRNAs). However, ncRNAs and competing endogenous RNA (ceRNA) networks which involved in NiONP-induced pulmonary fibrosis are still unclear. This study aimed to identify ncRNA-related ceRNA networks and investigate the role of the Wnt/β-catenin pathway in pulmonary fibrosis. Male Wistar rats were intratracheally instilled with 0.015, 0.06, and 0.24 mg/kg NiONPs twice a week for 9 weeks. First, we found there were 93 circularRNAs (circRNAs), 74 microRNAs (miRNAs), 124 long non-coding RNAs (lncRNAs), and 1675 messenger RNAs (mRNAs) differentially expressed through microarray analysis. Second, we constructed ceRNA networks among lncRNAs/circRNAs, miRNAs and mRNAs and identified two ceRNA networks (lncMelttl16/miR-382-5p/Hsd17b7 and circIqch/miR-181d-5p/Stat1) after real time-quantitative polymerase chain reaction (RT-qPCR) validation. Furthermore, based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, ncRNAs were found to be involved in biological processes and signaling pathways related to pulmonary fibrosis. KEGG analysis showed that NiONPs activated the Wnt/β-catenin pathway in rats. In vitro, HFL1 cells were treated with 0, 50, 100, and 200 μg/mL NiONPs for 24 h. We found that NiONPs induced collagen deposition and Wnt/β-catenin pathway activation. Moreover, a blockade of Wnt/β-catenin pathway alleviated NiONP-induced collagen deposition. In conclusion, these observations suggested that ncRNAs were crucial in pulmonary fibrosis development and that the Wnt/β-catenin pathway mediated the deposition of collagen.

XAV-939 inhibits epithelial-mesenchymal transformation in pulmonary fibrosis induced by crystalline silica via the Wnt signaling pathway

Silicosis is an occupational lung disease that results from long-term inhalation of free silica dust, the expression is sustained inflammation response, fibroblast hyperplasia, and excessive collagen deposit, bringing about pulmonary interstitial fibrosis. Wnt signaling pathway exists in various kinds of eukaryotic cells, is a highly conservative signaling pathway in biological evolution, and participates in cell proliferation, differentiation, migration, and polarity of physiological activity, such as in embryonic development, organ morphology, and tumor. In addition, it plays an important role in the progress of fibrosis disease. At present, studies related to silicosis are increasing, but the pathogenesis of silicosis still is not clear. In recent years, more and more studies have suggested that the Wnt signaling pathway could participate in the pathogenesis of silicosis fibrosis. In the study, we explored the mechanism of the Wnt signaling pathway in the pathogenesis of silicosis fibrosis and evaluated the effect of XAV-939 treatment epithelial-mesenchymal transformation (EMT) induced by silica. In addition, the results showed that EMT and activation of the Wnt signaling pathway would occur after stimulation of silica or TGF-β1. However, after treatment with the Wnt signaling pathway inhibitor XAV-939, EMT was reversed and the expression of the β-catenin decreased. These results suggested that the Wnt signaling pathway is associated with EMT induced by silica and it could be a potential target for the treatment of silicosis.

Endoplasmic reticulum stress mediates nickel chloride-induced epithelial‑mesenchymal transition and migration of human lung cancer A549 cells through Smad2/3 and p38 MAPK activation

BACKGROUND

The endoplasmic reticulum (ER) is a cellular membrane-bound organelle whereby proteins are synthesized, folded and glycosylated. Due to intrinsic (e.g., genetic) and extrinsic (e.g., environmental stressors) perturbations, ER proteostasis can be deregulated within cells which triggers unfolded protein response (UPR) as an adaptive stress response that may impact the migration and invasion properties of cancer cells. However, the mechanisms underlying the nickel compounds on lung cancer cell migration and invasion remain uncertain.

OBJECTIVE

We aimed to study whether Nickel chloride (NiCl₂) induces ER stress in lung cancer cells, and whether ER stress is involved in modulating epithelial-mesenchymal transition (EMT) and migration by Smads and MAPKs pathways activation following NiCl₂ treatment.

METHODS

A549 cells were treated with NiCl₂ to determine the cell viability using MTT assay. The wound healing assay was used to evaluate cell migration ability. ER ultrastructure was observed by transmission electron microscopy. Western blotting assay was performed to evaluate the protein levels of BIP, PERK, IRE-1α, XBP-1 s, and ATF6 for ER stress and UPR, E-cadherin and Vimentin for EMT, p-Smad2/3, p-ERK, p-JNK, and p-P38 for activation of Smads and MAPKs signaling pathways.

RESULTS

The expression levels of BIP, PERK, IRE-1α, XBP-1 s, and ATF6 were significantly increased following treatment with NiCl₂ in time- and dose-effect relationship. The ER stress inhibitor 4-PBA downregulated the expression levels of the above five proteins, and reversed the decrease in E-cadherin protein level and the increase in vimentin protein expression and cell migration abilities caused by NiCl₂. Furthermore, 4-PBA significantly reduced nickel chloride-induced Smad2/3 and p38 MAPK pathway activation, while not affected ERK and JNK MAPK pathways.

CONCLUSION

NiCl₂ triggers ER stress and UPR in A549 cells. Moreover, 4-PBA alleviates NiCl₂-induced EMT and migration ability of A549 cells possibly through the Smad2/3 and p38 MAPK pathways activation, rather than ERK and JNK MAPK pathways.

Nickel nanoparticles induce epithelial-mesenchymal transition in human bronchial epithelial cells via the HIF-1α/HDAC3 pathway

We and others have previously demonstrated that exposure to nickel nanoparticles (Nano-Ni) caused fibrogenic and carcinogenic effects; however, the underlying mechanisms are still not fully understood. This study aimed to investigate the effects of Nano-Ni on epithelial-mesenchymal transition (EMT) in human bronchial epithelial cells (BEAS-2B) and its underlying mechanisms since EMT is involved in both cancer pathogenesis and tissue fibrosis. Our results showed that exposure to Nano-Ni, compared to the control Nano-TiO2, caused a remarkable decrease in the expression of E-cadherin and an increase in the expression of vimentin and α-SMA, indicating an inducible role of Nano-Ni in EMT development in human bronchial epithelial cells. HIF-1α nuclear accumulation, HDAC3 upregulation, and decreased histone acetylation were also observed in the cells exposed to Nano-Ni, but not in those exposed to Nano-TiO2. Pretreatment of the cells with a specific HIF-1α inhibitor, CAY10585, or HIF-1α-specific siRNA transfection prior to Nano-Ni exposure resulted in the restoration of E-cadherin and abolished Nano-Ni-induced upregulation of vimentin and α-SMA, suggesting a crucial role of HIF-1α in Nano-Ni-induced EMT development. CAY10585 pretreatment also attenuated the HDAC3 upregulation and increased histone acetylation. Inhibition of HDAC3 with specific siRNA significantly restrained Nano-Ni-induced reduction in histone acetylation and restored EMT-related protein expression to near control levels. In summary, our findings suggest that exposure to Nano-Ni promotes the development of EMT in human bronchial epithelial cells by decreasing histone acetylation through HIF-1α-mediated HDAC3 upregulation. Our findings may provide information for further understanding of the molecular mechanisms of Nano-Ni-induced fibrosis and carcinogenesis.

LncRNA MEG3 ameliorates NiO nanoparticles-induced pulmonary inflammatory damage via suppressing the p38 mitogen activated protein kinases pathway

The lung inflammatory damage could result from the nickel oxide nanoparticles (NiO NPs), in which the underlying mechanism is still unclear. This article explored the roles of long noncoding RNA maternally expressed gene 3 (lncRNA MEG3) and p38 mitogen activated protein kinases (p38 MAPK) pathway in pulmonary inflammatory injury induced by NiO NPs. Wistar rats were treated with NiO NPs suspensions (0.015, 0.06, and 0.24 mg/kg) by intratracheal instillation twice-weekly for 9 weeks. Meanwhile, A549 cells were treated with NiO NPs suspensions (25, 50, and 100 μg/ml) for 24 h. It can be concluded that the NiO NPs did trigger pulmonary inflammatory damage, which was confirmed by the histopathological examination, abnormal changes of inflammatory cells and inflammatory cytokines (IL-1β, IL-6, TGF-β1, TNF-α, IFN-γ, IL-10, CXCL-1 and CXCL-2) in bronchoalveolar lavage fluid (BALF), pulmonary tissue and cell culture supernatant. Furthermore, NiO NPs activated the p38 MAPK pathway and downregulated MEG3 in vivo and in vitro. However, p38 MAPK pathway inhibitor (10 μM SB203580) reversed the alterations in the expression levels of inflammatory cytokines induced by NiO NPs. Meanwhile, over-expressed MEG3 significantly suppressed NiO NPs-induced p38 MAPK pathway activation and inflammatory cytokines changes. Overall, the above results proved that over-expression of lncRNA MEG3 reduced NiO NPs-induced inflammatory damage by preventing the activation of p38 MAPK pathway.

LncRNA MEG3 restrained pulmonary fibrosis induced by NiO NPs via regulating hedgehog signaling pathway-mediated autophagy

Long noncoding RNA maternally expressed gene 3 (lncRNA MEG3) was down-regulated in pulmonary fibrosis of rats induced by Nickel oxide nanoparticles (NiO NPs), while the downstream regulatory mechanisms of MEG3 remain unclear. This study aimed to investigate the relationship among MEG3, Hedgehog (Hh) signaling pathway and autophagy in pulmonary fibrosis caused by NiO NPs. The pulmonary fibrosis model in rats was constructed by intratracheal instillation of 0.015, 0.06, and 0.24 mg/kg NiO NPs twice a week for 9 weeks. Collagen deposition model was established by treating A549 cells with 25, 50, and 100 μg/mL NiO NPs for 24 h. Our results indicated that NiO NPs activated Hh pathway, down-regulated the expression of MEG3, and reduced autophagy activity in vivo and in vitro. Meanwhile, the autophagy process was promoted by Hh pathway inhibitor (CDG-0449), while the collagen formation in A549 cells was reduced by autophagy activator (Rapamycin). Furthermore, the overexpressed MEG3 inhibited the activation of Hh pathway, resulting in autophagy activity enhancement along with collagen formation reduction. In summary, lncRNA MEG3 can restrain pulmonary fibrosis induced by NiO NPs via regulating hedgehog signaling pathway-mediated autophagy, which may serve as a potential therapeutic strategy for pulmonary fibrosis.

Transcriptional repression of E-cadherin in nickel-exposed lung epithelial cells mediated by loss of Sp1 binding at the promoter

E-cadherin plays a central role in the stability of epithelial tissues by facilitating cell-cell adhesion. Loss of E-cadherin expression is a hallmark of epithelial-mesenchymal transition (EMT), a major event in the pathogenesis of several lung diseases. Our earlier studies showed that nickel, a ubiquitous environmental toxicant, induced EMT by persistently downregulating E-cadherin expression in human lung epithelial cells and that the EMT remained irreversible postexposure. However, the molecular basis of persistent E-cadherin downregulation by nickel exposure is not understood. Here, our studies show that the binding of transcription factor Sp1 to the promoter of E-cadherin encoding gene, CDH1, is essential for its expression. Nickel exposure caused a loss of Sp1 binding at the CDH1 promoter, resulting in its downregulation and EMT induction. Loss of Sp1 binding at the CDH1 promoter was associated with an increase in the binding of ZEB1 adjacent to the Sp1 binding site. ZEB1, an EMT master regulator persistently upregulated by nickel exposure, is a negative regulator of CDH1. CRISPR-Cas9-mediated knockout of ZEB1 restored Sp1 binding at the CDH1 promoter. Furthermore, ZEB1 knockout rescued E-cadherin expression and re-established the epithelial phenotype. Since EMT is associated with a number of nickel-exposure-associated chronic inflammatory lung diseases including asthma, fibrosis and cancer and metastasis, our findings provide new insights into the mechanisms associated with nickel pathogenesis.

Epithelial-mesenchymal transition: Insights into nickel-induced lung diseases

Nickel compounds are environmental toxicants, prevalent in the atmosphere due to their widespread use in several industrial processes, extensive consumption of nickel containing products, as well as burning of fossil fuels. Exposure to nickel is associated with a multitude of chronic inflammatory lung diseases including asthma, chronic obstructive pulmonary disease (COPD) and pulmonary fibrosis. In addition, nickel exposure is implicated in the development of nasal and lung cancers. Interestingly, a common pathogenic mechanism underlying the development of diseases associated with nickel exposure is epithelial-mesenchymal transition (EMT). EMT is a process by which the epithelial cells lose their junctions and polarity and acquire mesenchymal traits, including increased ability to migrate and invade. EMT is a normal and essential physiological process involved in differentiation, development and wound healing. However, EMT also contributes to a number of pathological conditions, including fibrosis, cancer and metastasis. Growing evidence suggest that EMT induction could be an important outcome of nickel exposure. In this review, we discuss the role of EMT in nickel-induced lung diseases and the mechanisms associated with EMT induction by nickel exposure.

LncRNA MEG3 Involved in NiO NPs-Induced Pulmonary Fibrosis via Regulating TGF-β1-Mediated PI3K/AKT Pathway

Long noncoding RNA maternally expressed gene 3 (MEG3) involves in fibrotic diseases, but its role in nickel oxide nanoparticles (NiO NPs)-induced pulmonary fibrosis remains unclear. The present study aimed to explore the relationships among MEG3, transforming growth factor-β1 (TGF-β1) and phosphoinositide 3-kinase (PI3K)/AKT pathway in NiO NPs-induced pulmonary fibrosis. Wistar rats were intratracheally instilled with NiO NPs twice a week for 9 weeks, and human lung adenocarcinoma epithelial cells (A549 cells) were exposed to NiO NPs for 24 h. The pathological alterations and increased hydroxyproline indicated that NiO NPs caused pulmonary fibrosis in rats. The up-regulated type I collagen (Col-I) suggested that NiO NPs-induced collagen deposition in A549 cells. Meanwhile, NiO NPs could significantly down-regulate MEG3, up-regulate TGF-β1 and activate PI3K/AKT signaling pathway both in vivo and in vitro. However, we found that the PI3K/AKT pathway activated by NiO NPs could be suppressed by 10 μM TGF-β1 inhibitor (SB431542) in A549 cells. The protein markers (Col-I, Fibronectin, and alpha-smooth muscle actin) of collagen deposition up-regulated by NiO NPs were reduced by 10 μM PI3K inhibitor (LY294002). Furthermore, we further found that overexpressed MEG3 inhibited the expression of TGF-β1, resulting in the inactivation of PI3K/AKT pathway and the reduction of collagen formation. In summary, our results validated that MEG3 could arrest NiO NPs-induced pulmonary fibrosis via inhibiting TGF-β1-mediated PI3K/AKT pathway.

TGF‑β1: Gentlemanly orchestrator in idiopathic pulmonary fibrosis (Review)

Idiopathic pulmonary fibrosis (IPF) is a worldwide disease characterized by the chronic and irreversible decline of lung function. Currently, there is no drug to successfully treat the disease except for lung transplantation. Numerous studies have been devoted to the study of the fibrotic process of IPF and findings showed that transforming growth factor‑β1 (TGF‑β1) plays a central role in the development of IPF. TGF‑β1 promotes the fibrotic process of IPF through various signaling pathways, including the Smad, MAPK, and ERK signaling pathways. There are intersections between these signaling pathways, which provide new targets for researchers to study new drugs. In addition, TGF‑β1 can affect the fibrosis process of IPF by affecting oxidative stress, epigenetics and other aspects. Most of the processes involved in TGF‑β1 promote IPF, but TGF‑β1 can also inhibit it. This review discusses the role of TGF‑β1 in IPF.

Astragaloside IV alleviates silica‑induced pulmonary fibrosis via inactivation of the TGF‑β1/Smad2/3 signaling pathway

The aim of the present study was to investigate the anti-fibrotic effects of astragaloside IV (ASV) in silicosis rats, and to further explore the potential underlying molecular mechanisms. A silica-induced rat model of pulmonary fibrosis was successfully constructed. Hematoxylin and eosin and Masson's trichrome staining were performed to observe the pathological changes in lung tissues. Immunohistochemical analysis was used to assess the expression levels of Collagen I, fibronectin and α-smooth muscle actin (α-SMA). A hemocytometer and Giemsa staining were used to evaluate the cytological characteristics of the bronchoalveolar lavage fluid. ELISA was used to detect the levels of the inflammatory cytokines tumor necrosis factor-α, interleukin (IL)-1β and IL-6. Reverse transcription-quantitative PCR and western blotting were performed to detect the mRNA and protein expression levels of genes associated with the transforming growth factor (TGF)-β1/Smad signaling pathway. ASV alleviated silica-induced pulmonary fibrosis, and reduced the expression of collagen I, fibronectin and α-SMA. In addition, the results of the present study suggested that the ASV-mediated anti-pulmonary fibrosis response may involve reduction of inflammation and oxidative stress. More importantly, ASV suppressed silica-induced lung fibroblast fibrosis via the TGF-β1/Smad signaling pathway, thereby inhibiting the progression of silicosis. In conclusion, the present study indicated that ASV may prevent silicosis-induced fibrosis by reducing the expression of Collagen I, fibronectin and α-SMA, and reducing the inflammatory response and oxidative stress, and these effects may be mediated by inhibiting the activation of the TGF-β1/Smad signaling pathway.