Cigarette smoke-induced EGFR activation promotes epithelial mesenchymal migration of human retinal pigment epithelial cells through regulation of the FAK-mediated Syk/Src pathway

The different response of PM2.5 stimulated nasal epithelial spheroids in control, asthma and COPD groups

BACKGROUND

Pathobiology of asthma and chronic obstructive pulmonary disease (COPD) is associated with changes among respiratory epithelium structure and function. Increased levels of PM2.5 from urban particulate matter (UPM) are correlated with enlarged rate of asthma and COPD morbidity as well as acute disease exacerbation. It has been suggested that pre-existing pulmonary obstructive diseases predispose epithelium for different biological response than in healthy airways. The aim of this study was to assess the impact of PM2.5 on the biological response of healthy as well as asthma and COPD respiratory epithelium using 3D/spheroid culture model.

METHODS

The spheroids from 5 healthy controls, 8 asthma patients, and 8 COPD patients were exposed to 100 µg/ml of PM2.5 for 24 h.

RESULTS

The common pattern for healthy asthma and COPD epithelium inflammatory response to PM2.5 stimulation include the increase in IL-1β, IL-6, IL-8 mRNA expression, and secretion of IL-6. Asthmatic spheroids produced higher amount of TNF-α and IL-8, whereas COPD spheroids expressed increased mRNA level of MUC5AC and decreased level of MMP7. PM2.5 treatment induced changes in AHR and TLR4 expression on secretory epithelium in COPD.

CONCLUSION

The response of airway epithelium to air pollution is different in healthy people than in obstructive lung disease patients. The impairment of airway epithelium in asthma and COPD changes their response to toxic environmental stimuli. This physiological dysfunction might be associated with diseases exacerbation of obstructive lung diseases.

Inhibition of EGFR attenuates EGF-induced activation of retinal pigment epithelium cell via EGFR/AKT signaling pathway

AIM

To explore the effect of epidermal growth factor receptor (EGFR) inhibition by erlotinib and EGFR siRNA on epidermal growth factor (EGF)-induced activation of retinal pigment epithelium (RPE) cells.

METHODS

Human RPE cell line (ARPE-19 cells) was activated by 100 ng/mL EGF. Erlotinib and EGFR siRNA were used to intervene EGF treatment. Cellular viability, proliferation, and migration were detected by methyl thiazolyl tetrazolium (MTT) assay, bromodeoxyuridine (BrdU) staining assay and wound healing assay, respectively. EGFR/protein kinase B (AKT) pathway proteins and N-cadherin, α-smooth muscle actin (α-SMA), and vimentin were tested by Western blot assay. EGFR was also determined by immunofluorescence staining.

RESULTS

EGF treatment for 24h induced a significant increase of ARPE-19 cells' viability, proliferation and migration, phosphorylation of EGFR/AKT proteins, and decreased total EGFR expression. Erlotinib suppressed ARPE-19 cells' viability, proliferation and migration through down regulating total EGFR and AKT protein expressions. Erlotinib also inhibited EGF-induced an increase of proliferative and migrative ability in ARPE-19 cells and clearly suppressed EGF-induced EGFR/AKT proteins phosphorylation and decreased expression of N-cadherin, α-SMA, and vimentin proteins. Similarly, EGFR inhibition by EGFR siRNA significantly affected EGF-induced an increase of cell proliferation, viability, and migration, phosphorylation of EGFR/AKT proteins, and up-regulation of N-cadherin, α-SMA, and vimentin proteins.

CONCLUSION

Erlotinib and EGFR-knockdown suppress EGF-induced cell viability, proliferation, and migration via EGFR/AKT pathway in RPE cells. EGFR inhibition may be a possible therapeutic approach for proliferative vitreoretinopathy (PVR).

Network Pharmacology-Based Identification of Key Targets of Ziyin Mingmu Pills Acting on Age-Related Macular Degeneration

Objective

This study is designed to find out the molecular targets of effective Chinese medicine Ziyin Mingmu pills (ZMPs) in treating age-related macular degeneration (AMD) based on network pharmacology and experimental data.

Methods

A comprehensive network pharmacology strategy that consists of three sequential modules (drug-disease target molecular docking, enrichment analysis, and external verification) was carried out to identify potential targets of ZMPs acting on AMD.

Results

The active ingredients of ZMPs targeting 66 genes have effects on the process of AMD. GO and KEGG pathway enrichment analyses suggested that response to oxidative stress, regulation of angiogenesis, and lipid and atherosclerosis might serve as the most important signaling pathways in ZMPs for AMD treatment. Combined with the GSE29801 dataset for further analysis, two key genes, EGFR and VEGFA, were identified. Immune infiltration analysis showed that there was a strong association between EGFR and immune cell content. In addition, images were acquired following 24 h in the scratch experiment showed that ZMPs can reduce the percentage of wound healing distance. The Western blot assay found that ZMPs increased the expression of EGFR and decreased the expression of VEGFA.

Conclusion

This study sheds light on some mechanisms of ZMP therapy for AMD, particularly the effect of ZMP on the oxidative stress in RPE and cell survival and angiogenesis in AMD. We propound ZMPs as a promising strategy to intervene in the process of AMD.

Spleen Tyrosine Kinase Mediates Microglial Activation in Mice With Diabetic Retinopathy

Purpose

Diabetic retinopathy (DR) is a leading cause of blindness in developed countries, in which microglial activation is involved. However, the mechanism of microglial activation in DR remains largely unknown.

Methods

We used Cx3cr1^CreERT2; Syk^fl/fl mice to knockout microglial spleen tyrosine kinase (Syk) in the retina of mice (cKO mice) after streptozotocin injection to induce diabetes. We also isolated primary retinal microglia from wild-type and cKO mice, respectively, to explore the role of microglial Syk in DR.

Results

The deletion of microglial Syk in the retina of mice or in the primary retinal microglia inhibited microglial activation and inflammatory response, eventually leading to the improvement of DR by regulating the expressions of interferon regulatory factor 8 (Irf8) and Pu.1 both in vivo and in vitro.

Conclusions

The deletion of microglial Syk in the retina effectively ameliorated microglial activation-induced DR, suggesting the potential of microglial Syk as a therapeutic target for DR.

Translational Relevance

Microglial spleen tyrosine kinase might serve as a potential therapeutic target for diabetic retinopathy.

Oxidative and Nitrosative Stress in Age-Related Macular Degeneration: A Review of Their Role in Different Stages of Disease

Although the exact pathogenetic mechanisms leading to age-related macular degeneration (AMD) have not been clearly identified, oxidative damage in the retina and choroid due to an imbalance between local oxidants/anti-oxidant systems leading to chronic inflammation could represent the trigger event. Different in vitro and in vivo models have demonstrated the involvement of reactive oxygen species generated in a highly oxidative environment in the development of drusen and retinal pigment epithelium (RPE) changes in the initial pathologic processes of AMD; moreover, recent evidence has highlighted the possible association of oxidative stress and neovascular AMD. Nitric oxide (NO), which is known to play a key role in retinal physiological processes and in the regulation of choroidal blood flow, under pathologic conditions could lead to RPE/photoreceptor degeneration due to the generation of peroxynitrite, a potentially cytotoxic tyrosine-nitrating molecule. Furthermore, the altered expression of the different isoforms of NO synthases could be involved in choroidal microvascular changes leading to neovascularization. The purpose of this review was to investigate the different pathways activated by oxidative/nitrosative stress in the pathogenesis of AMD, focusing on the mechanisms leading to neovascularization and on the possible protective role of anti-vascular endothelial growth factor agents in this context.

Common Genes Involved in Autophagy, Cellular Senescence and the Inflammatory Response in AMD and Drug Discovery Identified via Biomedical Databases

Purpose

Retinal pigment epithelial cell autophagy dysfunction, cellular senescence, and the retinal inflammatory response are key pathogenic factors in age-related macular degeneration (AMD), which has been reviewed in our previously work in 2019. This study aims to identify genes collectively involved in these three biological processes and target drugs in AMD.

Methods

The pubmed2ensembl database was used to perform text mining. The GeneCodis database was applied to analyze gene ontology biological process and the KEGG pathway. The STRING database was used to analyze protein–protein interaction analysis and hub genes were identified by the Cytoscape software. The Drug Gene Interaction Database was used to perform drug–gene interactions.

Results

We identified 62 genes collectively involved in AMD, autophagy, cellular senescence, and inflammatory response, 19 biological processes including 42 genes, 11 enriched KEGG pathways including 37 genes, and 12 hub genes step by step via the above biomedical databases. Finally, five hub genes (IL-6, VEGF-A, TP53, IL-1β, and transforming growth factor [TGF]-β1) and their specific interaction modes were identified, corresponding with 24 target drugs with therapeutic potential for AMD.

Conclusions

IL-6, VEGF-A, TP53, IL-1β, and TGF-β1 are pivotal in autophagy, cellular senescence, and the inflammatory response in AMD, corresponding with 24 drugs with therapeutic potential for AMD, providing definite molecular mechanisms for further research and new possibilities for AMD treatment in the future.

Translational Relevance

IL-6, VEGF-A, TP53, IL-1β, and TGF-β1 may be new targets for AMD gene therapy and drug development.

The Impact of Oxidative Stress on Blood-Retinal Barrier Physiology in Age-Related Macular Degeneration

The blood retinal barrier (BRB) is a fundamental eye component, whose function is to select the flow of molecules from the blood to the retina and vice-versa, and its integrity allows the maintenance of a finely regulated microenvironment. The outer BRB, composed by the choriocapillaris, the Bruch's membrane, and the retinal pigment epithelium, undergoes structural and functional changes in age-related macular degeneration (AMD), the leading cause of blindness worldwide. BRB alterations lead to retinal dysfunction and neurodegeneration. Several risk factors have been associated with AMD onset in the past decades and oxidative stress is widely recognized as a key factor, even if the exact AMD pathophysiology has not been exactly elucidated yet. The present review describes the BRB physiology, the BRB changes occurring in AMD, the role of oxidative stress in AMD with a focus on the outer BRB structures. Moreover, we propose the use of cerium oxide nanoparticles as a new powerful anti-oxidant agent to combat AMD, based on the relevant existing data which demonstrated their beneficial effects in protecting the outer BRB in animal models of AMD.

Correlation between FAK and EGF-Induced EMT in Colorectal Cancer Cells

Epithelial-mesenchymal transition (EMT) plays an important role in the invasion and metastasis of colorectal cancer, which is mediated by FAK and EGF. However, whether FAK participates in EMT in colorectal cancer cells through the EGF/EGFR signaling pathway remains unknown. The aim of this study was to investigate the effector mechanisms of FAK in the process of EGF-induced EMT in colorectal cancer cells and to determine whether miR-217 is involved in this process. Caco-2 cancer cells were routinely cultured with and without treatment with 100 ng/mL EGF, and changes in cell morphology were observed using an inverted microscope. In addition, a transwell assay was used to detect cell migration under the condition of EGF treatment. The expression of FAK, pFAK, E-cadherin, vimentin, and β actin was assessed by western blotting, and the expression of miR-217 was assessed using real-time PCR. We found that EGF induced EMT in colorectal cancer cells and enhanced cell migration and invasion ability. Moreover, FAK was involved in the EGF-induced EMT of colorectal cancer cells. EGF upregulated the expression of E-cadherin in colorectal cancer cells by activating FAK, and miR-217 was found to participate in EGF-induced EMT in colorectal cancer cells. Our findings indicate that EGF induces EMT in colorectal cancer cells by activating FAK, and miR-217 is involved in the EGF/FAK/E-cadherin signaling pathway.

Luteolin attenuates migration and invasion of lung cancer cells via suppressing focal adhesion kinase and non-receptor tyrosine kinase signaling pathway

BACKGROUND/OBJECTIVES

Non-small cell lung cancer is mostly recognized among other types of lung cancer with a poor prognosis by cause of chemotherapeutic resistance and increased metastasis. Luteolin has been found to decrease cell metastasis. However, its underlying mechanisms remain unresolved. The objective of this study was to examine the effect (and its mechanism) of luteolin on the migration and invasion of human non-small cell lung cancer A549 cells.

MATERIALS/METHODS

Cell viability was investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Wound healing and transwell assays were evaluated to assess migration and invasion, respectively. Western blot analysis and immunofluorescence were further performed to investigate the role of luteolin and its mechanisms of action.

RESULTS

Administration with up to 40 µM luteolin showed no cytotoxic activity on lung cancer A549 cells or non-cancer MRC-5 cells. Additionally, luteolin at 20-40 µM significantly suppressed A549 cells' migration, invasion, and the formation of filopodia in a concentration-dependent manner at 24 h. This is similar with western blot analysis, which revealed diminished the phosphorylated focal adhesion kinase (pFAK), phosphorylated non-receptor tyrosine kinase (pSrc), Ras-related C3 botulinum toxin substrate 1 (Rac1), cell division control protein 42 (Cdc42), and Ras homolog gene family member A (RhoA) expression levels.

CONCLUSIONS

Overall, our data indicate that luteolin plays a role in controlling lung cancer cells' migration and invasion via Src/FAK and its downstream Rac1, Cdc42, and RhoA pathways. Luteolin might be considered a promising candidate for suppressing invasion and metastasis of lung cancer cells.

Inhibitory effect of nintedanib on VEGF secretion in retinal pigment epithelial cells induced by exposure to a necrotic cell lysate

Necrosis is a form of cell death that results in rupture of the plasma membrane and the release of cellular contents, and it can give rise to sterile inflammation in the retina and other tissues. The secretion of vascular endothelial growth factor (VEGF) by retinal pigment epithelial (RPE) cells contributes to retinal homeostasis as well as to pathological angiogenesis. We have now examined the effect of a necrotic cell lysate prepared from human RPE cells (NLR) on the release of VEGF by healthy RPE cells. We found that NLR markedly increased the release of VEGF from RPE cells and that this effect was attenuated by nintedanib, a multiple receptor tyrosine kinase inhibitor, whereas it was unaffected by inhibitors of NF-κB signaling or of caspase-1. NLR also induced the phosphorylation of extracellular signal-regulated kinase (Erk) and signal transducer and activator of transcription 3 (Stat3) in a manner sensitive to inhibition by nintedanib, although inhibitors of Erk and Stat3 signaling pathways did not affect NLR-induced VEGF secretion. In addition, nintedanib attenuated the development of choroidal neovascularization in mice. Our results have thus shown that a necrotic lysate of RPE cells induced VEGF secretion from healthy RPE cells and that this effect was mediated by receptor tyrosine kinase signaling. They therefore suggest that VEGF secretion by healthy RPE cells is a potential therapeutic target for retinal diseases associated with sterile inflammation and pathological angiogenesis.

Soluble Wood Smoke Extract Promotes Barrier Dysfunction in Alveolar Epithelial Cells through a MAPK Signaling Pathway

Wildfire smoke induces acute pulmonary distress and is of particular concern to risk groups such as the sick and elderly. Wood smoke (WS) contains many of the same toxic compounds as those found in cigarette smoke (CS) including polycyclic aromatic hydrocarbons, carbon monoxide, and free radicals. CS is a well-established risk factor for respiratory diseases such as asthma and COPD. Limited studies investigating the biological effects of WS on the airway epithelium have been performed. Using a cell culture-based model, we assessed the effects of a WS-infused solution on alveolar epithelial barrier function, cell migration, and survival. The average geometric mean of particles in the WS was 178 nm. GC/MS analysis of the WS solution identified phenolic and cellulosic compounds. WS exposure resulted in a significant reduction in barrier function, which peaked after 24 hours of continuous exposure. The junctional protein E-cadherin showed a prominent reduction in response to increasing concentrations of WS. Furthermore, WS significantly repressed cell migration following injury to the cell monolayer. There was no difference in cell viability following WS exposure. Mechanistically, WS exposure induced activation of the p44/42, but not p38, MAPK signaling pathway, and inhibition of p44/42 phosphorylation prevented the disruption of barrier function and loss of E-cadherin staining. Thus, WS may contribute to the breakdown of alveolar structure and function through a p44/42 MAPK-dependent pathway and may lead to the development and/or exacerbation of respiratory pathologies with chronic exposure.

Myofibroblasts in macular fibrosis secondary to neovascular age-related macular degeneration - the potential sources and molecular cues for their recruitment and activation

Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly in developed countries. Neovascular AMD (nAMD) accounts for 90% of AMD-related vision loss. Although intravitreal injection of VEGF inhibitors can improve vision in nAMD, approximately 1/3 of patients do not benefit from the therapy due to macular fibrosis. The molecular mechanism underlying the transition of the neovascular lesion to a fibrovascular phenotype remains unknown. Here we discussed the clinical features and risk factors of macular fibrosis secondary to nAMD. Myofibroblasts are key cells in fibrosis development. However, fibroblasts do not exist in the macula. Potential sources of myofibroblast precursors, the molecular cues in the macular microenvironment that recruit them and the pathways that control their differentiation and activation in macular fibrosis were also discussed. Furthermore, we highlighted the challenges in macular fibrosis research and the urgent need for better animal models for mechanistic and therapeutic studies.

Water-pipe smoking promotes epithelial-mesenchymal transition and invasion of human breast cancer cells via ERK1/ERK2 pathways

Background

With the increasing popularity of water-pipe smoking (WPS), it is critical to comprehend how WPS may affect women's health. The main goal of this study is to identify the potential outcome of WPS on human breast cancer progression.

Methods

Two breast cancer cell lines, MCF7 and BT20, were used in this investigation. We explored the outcome of WPS on cell morphology and cell invasion using inverted microscope and Biocoat Matrigel invasion chambers. On the other hand, Western blot was employed to study the expression patterns of key control genes of cell adhesion and invasion.

Results

Our data reveal that WPS induces epithelial-mesenchymal transition (EMT) of MCF7 and BT20 breast cancer cell lines; thus, WPS enhances cell invasion ability of both cell lines in comparison with their matched controls. More significantly, WPS provokes a down- and up-regulation of E-cadherin and focal adhesion kinase (FAK), respectively, which are important key regulators of cancer progression genes. Finally, our data point out that WPS incites the activation of Erk1/Erk2, which could be behind the stimulation of EMT and invasion as well as the deregulation of E-cadherin and FAK expression.

Conclusion

Our data show, for the first time, that WPS initiates EMT and stimulates cell invasion of breast cancer cells, which could incite metastatic development in breast cancer patients. Thus, we believe that further studies, both in vitro and in vivo, are required to elucidate the pathogenic outcome of WPS on cancer progression of several human carcinomas including breast.

Reduced graphene oxide triggered epithelial-mesenchymal transition in A549 cells

Graphene and its derivatives have exhibited wide potential applications in electronics, structural engineering and medicine. However, over utilization and untreated discharge may cause its distribution into environmental as well as biological chain, which raised the concerns of potential health risk as a potential hazard. Accumulating evidence has demonstrated that graphene derivatives induce lung fibrosis in vivo, so overall goal of this study was to explore the molecular mechanisms underlying the pulmonary fibrotic responses of reduced graphene oxide (rGO), using in vitro assays. Epithelial-mesenchymal transition (EMT) has profound effect on development of pulmonary fibrosis. Herein, we evaluated the EMT effect of rGO samples on A549 cells. Firstly, rGO penetrated through the A549 cells membrane into the cytosol by endocytosis and located in late endosome and/or lysosomes observed via transmission electron microscopy (TEM), and were well tolerant by cells. Secondly, rGO promoted the cell migration and invasion capacities at lower doses (below 10 μg/ml), but significantly inhibited the capacities at 20 μg/ml. Moreover, rGO-induced EMT were evidenced by decreased expression of epithelial marker like E-cadherin, β-catenin, Smad4 and increased expression of mesenchymal markers like Vimentin, VEGF-B, TWIST1. Based on our findings, it is supposed that rGO can effectively induce EMT through altering epithelial–mesenchymal transition markers in A549 cells.