Transforming growth factor beta1 induces epithelial-to-mesenchymal transition of A549 cells

A recombinant IL-1β vaccine attenuates bleomycin-induced pulmonary fibrosis in mice

Interleukin-1β (IL-1β) contributes to interstitial lung disease (ILD) and pulmonary fibrosis (PF), thus representing a potential therapeutic target for PF. In this study, we first verified the increased expression of IL-1β in human fibrotic lung specimens and mouse lung tissues after intratracheal (i.t.) instillation of bleomycin (BLM), after which the pro-inflammatory and pro-fibrotic effects of recombinant IL-1β were tested in mice. The results above suggested that vaccination against IL-1β could be an effective strategy for managing PF. An anti-IL-1β vaccine (PfTrx-IL-1β) was designed by incorporating two IL-1β-derived polypeptides, which have been verified as the key domains that mediate the binding of IL-1β to its type I receptor, into Pyrococcus furiosus thioredoxin (PfTrx). The fusion protein PfTrx-IL-1β was prepared by using E. coli expression system. The vaccine was well tolerated; it induced robust and long-lasting antibody responses in mice and neutralized the biological activity of IL-1β, as shown in cellular assays. Pre-immunization with PfTrx-IL-1β effectively protected mice from BLM-induced lung injury, inflammation, and fibrosis. In vitro experiments further showed that anti-PfTrx-IL-1β antibodies counteracted the effects of IL-1β concerning pro-inflammatory and pro-fibrotic cytokine production by primary mouse lung fibroblast, macrophages (RAW264.7), and type II alveolar epithelial cell (A549), primary mouse lung fibroblast activation and epithelial-mesenchymal transition (EMT) of alveolar epithelial cells. In addition, the vaccination did not compromise the anti-infection immunity in mice, as validated by a sepsis model. Our preliminary study suggests that the anti-IL-1β vaccine we prepared has the potential to be developed as a therapeutic measure for PF. Further experiments are warranted to evaluate whether IL-1β vaccination has the capacity of inhibiting chronic progressive PF and reversing established PF.

Changes in lung epithelial cell volatile metabolite profile induced by pro-fibrotic stimulation with TGF-β1

Volatile organic compounds (VOCs) have shown promise as potential biomarkers in idiopathic pulmonary fibrosis. Measuring VOCs in the headspace ofin vitromodels of lung fibrosis may offer a method of determining the origin of those detected in exhaled breath. The aim of this study was to determine the VOCs associated with two lung cell lines (A549 and MRC-5 cells) and changes associated with stimulation of cells with the pro-fibrotic cytokine, transforming growth factor (TGF)-β1. A dynamic headspace sampling method was used to sample the headspace of A549 cells and MRC-5 cells. These were compared to media control samples and to each other to identify VOCs which discriminated between cell lines. Cells were then stimulated with the TGF-β1 and samples were compared between stimulated and unstimulated cells. Samples were analysed using thermal desorption-gas chromatography-mass spectrometry and supervised analysis was performed using sparse partial least squares-discriminant analysis (sPLS-DA). Supervised analysis revealed differential VOC profiles unique to each of the cell lines and from the media control samples. Significant changes in VOC profiles were induced by stimulation of cell lines with TGF-β1. In particular, several terpenoids (isopinocarveol, sativene and 3-carene) were increased in stimulated cells compared to unstimulated cells. VOC profiles differ between lung cell lines and alter in response to pro-fibrotic stimulation. Increased abundance of terpenoids in the headspace of stimulated cells may reflect TGF-β1 cell signalling activity and metabolic reprogramming. This may offer a potential biomarker target in exhaled breath in IPF.

Pharmacological targeting of netrin-1 inhibits EMT in cancer

Epithelial-to-mesenchymal transition (EMT) regulates tumour initiation, progression, metastasis and resistance to anti-cancer therapy1-7. Although great progress has been made in understanding the role of EMT and its regulatory mechanisms in cancer, no therapeutic strategy to pharmacologically target EMT has been identified. Here we found that netrin-1 is upregulated in a primary mouse model of skin squamous cell carcinoma (SCC) exhibiting spontaneous EMT. Pharmacological inhibition of netrin-1 by administration of NP137, a netrin-1-blocking monoclonal antibody currently used in clinical trials in human cancer (ClinicalTrials.gov identifier NCT02977195 ), decreased the proportion of EMT tumour cells in skin SCC, decreased the number of metastases and increased the sensitivity of tumour cells to chemotherapy. Single-cell RNA sequencing revealed the presence of different EMT states, including epithelial, early and late hybrid EMT, and full EMT states, in control SCC. By contrast, administration of NP137 prevented the progression of cancer cells towards a late EMT state and sustained tumour epithelial states. Short hairpin RNA knockdown of netrin-1 and its receptor UNC5B in EPCAM+ tumour cells inhibited EMT in vitro in the absence of stromal cells and regulated a common gene signature that promotes tumour epithelial state and restricts EMT. To assess the relevance of these findings to human cancers, we treated mice transplanted with the A549 human cancer cell line-which undergoes EMT following TGFβ1 administration8,9-with NP137. Netrin-1 inhibition decreased EMT in these transplanted A549 cells. Together, our results identify a pharmacological strategy for targeting EMT in cancer, opening up novel therapeutic interventions for anti-cancer therapy.

RSV infection does not induce EMT

Respiratory syncytial virus (RSV) infection does not cause severe disease in most of us despite suffering from multiple RSV infections in our lives. However, infants, young children, older adults, and immunocompromised patients are unfortunately vulnerable to RSV-associated severe diseases. A recent study suggested that RSV infection causes cell expansion, resulting in bronchial wall thickening in vitro. Whether the virus-induced changes in the lung airway resemble epithelial-mesenchymal transition (EMT) is still unknown. Here, we report that RSV does not induce EMT in three different in vitro lung models: the epithelial A549 cell line, primary normal human bronchial epithelial cells, and pseudostratified airway epithelium. We found that RSV increases the cell surface area and perimeter in the infected airway epithelium, which is distinct from the effects of a potent EMT inducer, TGF-β1-driven cell elongation-indicative of cell motility. A genome-wide transcriptome analysis revealed that both RSV and TGF-β1 have distinct modulation patterns of the transcriptome, which suggests that RSV-induced changes are distinct from EMT.

Anti-TGF-β1 aptamer enhances therapeutic effect of tyrosine kinase inhibitor, gefitinib, on non-small cell lung cancer in xenograft model

Transforming growth factor β (TGF-β) is a multifunctional cytokine that plays crucial pathophysiological roles in various diseases, such as cancer and fibrosis. However, the disease modulation by targeting TGF-β1 isoform remains to be established, regardless of several studies employed with limited antibodies. Here, we developed an RNA aptamer to human active TGF-β1, named APT-β1, and characterized its properties in vitro and in vivo. APT-β1 bound to human and mouse active TGF-β1 proteins with high affinity and specificity and strongly inhibited TGF-β1-induced downstream signaling and cell morphology with 50% inhibition concentration (IC50) values at picomolar concentrations. In a xenograft mouse model of non-small cell lung cancer, APT-β1 alone showed no appreciable effect on tumor growth, while it greatly enhanced the anti-tumor effect of gefitinib, an approved tyrosine kinase inhibitor. These findings strongly suggest that the anti-TGF-β1 medication may be a promising cancer therapy to suppress repopulation of lung cancer in combination with certain anti-cancer drugs, such as gefitinib.

Statistical parametrization of cell cytoskeleton reveals lung cancer cytoskeletal phenotype with partial EMT signature

Epithelial–mesenchymal Transition (EMT) is a multi-step process that involves cytoskeletal rearrangement. Here, developing and using an image quantification tool, Statistical Parametrization of Cell Cytoskeleton (SPOCC), we have identified an intermediate EMT state with a specific cytoskeletal signature. We have been able to partition EMT into two steps: (1) initial formation of transverse arcs and dorsal stress fibers and (2) their subsequent conversion to ventral stress fibers with a concurrent alignment of fibers. Using the Orientational Order Parameter (OOP) as a figure of merit, we have been able to track EMT progression in live cells as well as characterize and quantify their cytoskeletal response to drugs. SPOCC has improved throughput and is non-destructive, making it a viable candidate for studying a broad range of biological processes. Further, owing to the increased stiffness (and by inference invasiveness) of the intermediate EMT phenotype compared to mesenchymal cells, our work can be instrumental in aiding the search for future treatment strategies that combat metastasis by specifically targeting the fiber alignment process.

A computational method for automated quantification of actin stress fiber alignment in fluorescence images of cultured cells is presented, used to detect changes in stress fiber organization during EMT, with pathways regulating actin dynamics manipulated leading to the discovery of a cytoskeletal phenotype.

Microenvironmental Factors Modulating Tumor Lipid Metabolism: Paving the Way to Better Antitumoral Therapy

Metabolic reprogramming is one of the emerging hallmarks of cancer and is driven by both the oncogenic mutations and challenging microenvironment. To satisfy the demands of energy and biomass for rapid proliferation, the metabolism of various nutrients in tumor cells undergoes important changes, among which the aberrant lipid metabolism has gained increasing attention in facilitating tumor development and metastasis in the past few years. Obstacles emerged in the aspect of application of targeting lipid metabolism for tumor therapy, due to lacking of comprehensive understanding on its regulating mechanism. Tumor cells closely interact with stromal niche, which highly contributes to metabolic rewiring of critical nutrients in cancer cells. This fact makes the impact of microenvironment on tumor lipid metabolism a topic of renewed interest. Abundant evidence has shown that many factors existing in the tumor microenvironment can rewire multiple signaling pathways and proteins involved in lipid metabolic pathways of cancer cells. Hence in this review, we summarized the recent progress on the understanding of microenvironmental factors regulating tumor lipid metabolism, and discuss the potential of modulating lipid metabolism as an anticancer approach.

Emergence of Cardiac Glycosides as Potential Drugs: Current and Future Scope for Cancer Therapeutics

Cardiac glycosides are natural sterols and constitute a group of secondary metabolites isolated from plants and animals. These cardiotonic agents are well recognized and accepted in the treatment of various cardiac diseases as they can increase the rate of cardiac contractions by acting on the cellular sodium potassium ATPase pump. However, a growing number of recent efforts were focused on exploring the antitumor and antiviral potential of these compounds. Several reports suggest their antitumor properties and hence, today cardiac glycosides (CG) represent the most diversified naturally derived compounds strongly recommended for the treatment of various cancers. Mutated or dysregulated transcription factors have also gained prominence as potential therapeutic targets that can be selectively targeted. Thus, we have explored the recent advances in CGs mediated cancer scope and have considered various signaling pathways, molecular aberration, transcription factors (TFs), and oncogenic genes to highlight potential therapeutic targets in cancer management.

FAM13A as potential therapeutic target in modulating TGF-β-induced airway tissue remodeling in COPD

Genome-wide association studies have shown that a gene variant in the Family with sequence similarity 13, member A (FAM13A) is strongly associated with reduced lung function and the appearance of respiratory symptoms in patients with chronic obstructive pulmonary disease (COPD). A key player in smoking-induced tissue injury and airway remodeling is the transforming growth factor-β1 (TGF-β1). To determine the role of FAM13A in TGF-β1 signaling, FAM13A^-/- airway epithelial cells were generated using CRISPR-Cas9, whereas overexpression of FAM13A was achieved using lipid nanoparticles. Wild-type (WT) and FAM13A^-/- cells were treated with TGF-β1, followed by gene and/or protein expression analyses. FAM13A^-/- cells augmented TGF-β1-induced increase in collagen type 1 (COL1A1), matrix metalloproteinase 2 (MMP2), expression compared with WT cells. This effect was mediated by an increase in β-catenin (CTNNB1) expression in FAM13A^-/- cells compared with WT cells after TGF-β1 treatment. FAM13A overexpression was partially protective from TGF-β1-induced COL1A1 expression. Finally, we showed that airway epithelial-specific FAM13A protein expression is significantly increased in patients with severe COPD compared with control nonsmokers, and negatively correlated with lung function. In contrast, β-catenin (CTNNB1), which has previously been linked to be regulated by FAM13A, is decreased in the airway epithelium of smokers with COPD compared with non-COPD subjects. Together, our data showed that FAM13A may be protective from TGF-β1-induced fibrotic response in the airway epithelium via sequestering CTNNB1 from its regulation on downstream targets. Therapeutic increase in FAM13A expression in the airway epithelium of smokers at risk for COPD, and those with mild COPD, may reduce the extent of airway tissue remodeling.

Effect of long noncoding RNAs on epithelial-mesenchymal transition in A549 cells and fibrotic human lungs

Long noncoding RNAs (LncRNAs) regulate epithelial-mesenchymal transition (EMT). EMT involves myofibroblast differentiation and pulmonary fibrosis (PF). We aimed to determine the expression profiles of HOTAIR, CARLo-5, and CD99P1 LncRNAs in EMT-mediated myofibroblast differentiation in A549 cells and fibrotic human lungs and to explain their roles. A group of A549s was stimulated with transforming growth factor β (TGF-β; 5 ng/ml) to induce EMT. The remaining A549s were incubated with 20 μM FH535 after 24 h of TGF-β treatment to inhibit EMT. A549s were collected at 0, 24, 36, and 48 h. Expressions of three LncRNAs and protein/genes related to EMT, myofibroblast differentiation, and PF were assayed by quantitative reverse-transcription polymerase chain reaction and Western blot analysis in A549s and fibrotic human lungs. The targets of three LncRNAs were investigated by bioinformatics methods. TGF-β stimulation resulted in increased expressions of three LncRNAs, ACTA2, COL1A1, SNAI1, CTNNB1, TCF4, LEF1, α-SMA, and active-β-catenin, and decreased E-cadherin at 24, 36, and 48 h in A549s. FH535 treatment regressed these alterations. But it increased HOTAIR expression at 36 h and did not increase E-cadherin at 48 h. Fibrotic human lungs were characterized by increased expressions of HOTAIR, CARLo-5, CD99P1, and miR-214, decreased expressions of miR-148b, miR-218-1, miR-7-1, and the presence of CARLo-5 and CD99P1 in HDAC1-LncRNAs coprecipitation products, but not HOTAIR. Bioinformatic analysis showed the interactions of three LncRNAs with both proteins and at least 13 microRNAs related to EMT and PF. In conclusion, HOTAIR, CARLo-5, and CD99P1 can regulate EMT-mediated myofibroblast differentiation through interacting with proteins and miRNAs associated with EMT and PF. These LncRNAs can be considered as potential targets to decrease EMT for treating PF.

EGF Induces Migration Independent of EMT or Invasion in A549 Lung Adenocarcinoma Cells

Tumors and the tumor microenvironment produce multiple growth factors that influence cancer cell behavior via various signal transduction pathways. Growth factors, like transforming growth factor β (TGFβ) and epidermal growth factor (EGF), have been shown to induce proliferation, migration, and invasion in different cell models. Both factors are frequently overexpressed in cancer and will often act in combination. Although both factors are being used as rational targets in clinical oncology, the similarities and differences of their contributions to cancer cell migration and invasion are not fully understood. Here we compared the impact of treating A549 lung adenocarcinoma cells with TGFβ, EGF, and both in combination by applying videomicroscopy, functional assays, immunoblotting, real-time PCR, and proteomics. Treatment with both factors stimulated A549 migration to a similar extent, but with different kinetics. The combination had an additive effect. EGF-induced migration depended on activation of the mitogen-activated protein kinase (MAPK) pathway. However, this pathway was dispensable for TGFβ-induced migration, despite a strong activation of this pathway by TGFβ. Proteome analysis (data are available via ProteomeXchange with identifier PXD023024) revealed an overlap in expression patterns of migration-related proteins and associated gene ontology (GO) terms by TGFβ and EGF. Further, only TGFβ induced the expression of epithelial to mesenchymal transition (EMT)-related proteins like matrix metalloproteinase 2 (MMP2). EGF, in contrast, made no major contribution to EMT marker expression on either the protein or the transcript level. In line with these expression patterns, TGFβ treatment significantly increased the invasive capacity of A549 cells, while EGF treatment did not. Moreover, the addition of EGF failed to enhance TGFβ-induced invasion. Overall, these data suggest that TGFβ and EGF can partly compensate for each other for stimulation of cell migration, but abrogation of TGFβ signaling may be more suitable to suppress cell invasion.

Fibroblast Growth Factor 2 Augments Transforming Growth Factor Beta 1 Induced Epithelial-mesenchymal Transition in Lung Cell Culture Model

Impaired lung epithelial cell regeneration following injury may contribute to the development of pulmonary fibrosis. Epithelial-mesenchymal transition (EMT) is a critical event in embryonic development, wound healing following injury, and even cancer progression. Previous studies have shown that the combination of transforming growth factor beta-1 (TGFβ1) and fibroblast growth factor 2 (FGF2) induces EMT during cancer metastasis. However, this synergy remains to be elucidated in inducing EMT associated with wound healing after injury. We set out this study to determine the effect of fibroblast growth factor 2 (FGF2) on TGFβ1-induced EMT in the human lung epithelium. BEAS-2B and A549 cells were treated with TGFβ1, FGF2, or both. EMT phenotype was investigated morphologically and by measuring mRNA expression levels; using quantitative real-time PCR. E-cadherin expression was assayed by western blot and immunofluorescence staining. Cell migration was confirmed using a wound-healing assay. TGFβ1 induced a morphological change and a significant increase in cell migration of BEAS-2B cells. TGFβ1 significantly reduced E-cadherin (CDH1) mRNA expression and markedly induced expression of N-cadherin (CDH2), tenascin C (TNC), fibronectin (FN), actin alpha 2 (ACTA2), and collagen I (COL1A1). While FGF2 alone did not significantly alter EMT gene expression, it enhanced TGFβ1-induced suppression of CDH1 and upregulation of ACTA2, but not TNC, FN, and CDH2. FGF2 significantly inhibited TGFβ1-induced COL1A1 expression. Furthermore, FGF2 maintained TGFβ1-induced morphologic changes and increased the migration of TGFβ1-treated cells. This study suggests a synergistic effect between TGFβ1 and FGF2 in inducing EMT in lung epithelial cells, which may play an important role in wound healing and tissue repair after injury.

Expression dynamics of integrin α2, α3, and αV upon osteogenic differentiation of human mesenchymal stem cells

Background

The differentiation of human mesenchymal stem cells (hMSCs) into osteoblasts (OBs) is a prerequisite for bone formation. However, little is known about the definitive surface markers for OBs during osteogenesis.

Methods

To study the surface markers on OBs, we generated and used monoclonal antibodies (MAbs) against surface molecules on transforming growth factor-β1 (TGF-β1)-treated cancer cells. The generated MAbs were further selected toward expression changes on hMSCs cultured with TGF-β1/bone morphogenetic protein-2 (BMP-2) or osteogenic differentiation medium (ODM) by flow cytometry. Immunoprecipitation and mass spectrometry were performed to identify target antigens of selected MAbs. Expression changes of the target antigens were evaluated in hMSCs, human periodontal ligament cells (hPDLCs), and human dental pulp cells (hDPCs) during osteogenic and adipogenic differentiation by quantitative polymerase chain reaction (qPCR) and flow cytometry. hMSCs were also sorted by the MAbs using magnetic-activated cell sorting system, and osteogenic potential of sorted cells was evaluated via Alizarin Red S (ARS) staining and qPCR.

Results

The binding reactivity of MR14-E5, one of the MAbs, was downregulated in hMSCs with ODM while the binding reactivity of ER7-A7, ER7-A8, and MR1-B1 MAbs was upregulated. Mass spectrometry and overexpression identified that MR14-E5, ER7-A7/ER7-A8, and MR1-B1 recognized integrin α2, α3, and αV, respectively. Upon osteogenic differentiation of hMSCs, the expression of integrin α2 was drastically downregulated, but the expression of integrin α3 and αV was upregulated in accordance with upregulation of osteogenic markers. Expression of integrin α3 and αV was also upregulated in hPDLCs and hDPCs during osteogenic differentiation. Cell sorting showed that integrin αV-high hMSCs have a greater osteogenic potential than integrin αV-low hMSCs upon the osteogenic differentiation of hMSCs. Cell sorting further revealed that the surface expression of integrin αV is more dramatically induced even in integrin αV-low hMSCs.

Conclusion

These findings suggest that integrin α3 and αV induction is a good indicator of OB differentiation. These findings also shed insight into the expression dynamics of integrins upon osteogenic differentiation of hMSCs and provide the reason why different integrin ligands are required for OB differentiation of hMSCs.

Cannabinoid receptor expression in non-small cell lung cancer. Effectiveness of tetrahydrocannabinol and cannabidiol inhibiting cell proliferation and epithelial-mesenchymal transition in vitro

Background/Objective

Patients with non-small cell lung cancer (NSCLC) develop resistance to antitumor agents by mechanisms that involve the epithelial-to-mesenchymal transition (EMT). This necessitates the development of new complementary drugs, e.g., cannabinoid receptors (CB1 and CB2) agonists including tetrahydrocannabinol (THC) and cannabidiol (CBD). The combined use of THC and CBD confers greater benefits, as CBD enhances the effects of THC and reduces its psychotropic activity. We assessed the relationship between the expression levels of CB1 and CB2 to the clinical features of a cohort of patients with NSCLC, and the effect of THC and CBD (individually and in combination) on proliferation, EMT and migration in vitro in A549, H460 and H1792 lung cancer cell lines.

Methods

Expression levels of CB1, CB2, EGFR, CDH1, CDH2 and VIM were evaluated by quantitative reverse transcription-polymerase chain reaction. THC and CBD (10–100 μM), individually or in combination (1:1 ratio), were used for in vitro assays. Cell proliferation was determined by BrdU incorporation assay. Morphological changes in the cells were visualized by phase-contrast and fluorescence microscopy. Migration was studied by scratch recolonization induced by 20 ng/ml epidermal growth factor (EGF).

Results

The tumor samples were classified according to the level of expression of CB1, CB2, or both. Patients with high expression levels of CB1, CB2, and CB1/CB2 showed increased survival reaching significance for CB1 and CB1/CB2 (p = 0.035 and 0.025, respectively). Both cannabinoid agonists inhibited the proliferation and expression of EGFR in lung cancer cells, and CBD potentiated the effect of THC. THC and CBD alone or in combination restored the epithelial phenotype, as evidenced by increased expression of CDH1 and reduced expression of CDH2 and VIM, as well as by fluorescence analysis of cellular cytoskeleton. Finally, both cannabinoids reduced the in vitro migration of the three lung cancer cells lines used.

Conclusions

The expression levels of CB1 and CB2 have a potential use as markers of survival in patients with NSCLC. THC and CBD inhibited the proliferation and expression of EGFR in the lung cancer cells studied. Finally, the THC/CBD combination restored the epithelial phenotype in vitro.

Transforming growth factor β-induced epithelial-to-mesenchymal signature predicts metastasis-free survival in non-small cell lung cancer

Transforming growth factor beta (TGFβ) plays a key role in regulating epithelial-to-mesenchymal transition (EMT). A gene expression signature (TGFβ-EMT) associated with TGFβ-induced EMT activities was developed using human Non-Small Cell Lung Carcinoma (NSCLC) cells treated with TGFβ-1 and subjected to Affymetrix microarray analysis. The final 105-probeset TGFβ-EMT signature covers 77 genes, and a NanoString assay utilized a subset of 60 of these genes (TGFβ-EMTN signature). We found that the TGFβ-EMT and TGFβ-EMT_N gene signatures predicted overall survival (OS) and metastasis-free survival (MFS). The TGFβ-EMT signature was validated as prognostic of 5-year MFS in 3 cohorts: a 133 NSCLC tumor dataset (P = 0.0002), a NanoString assays of RNA isolated from formalin-fixed paraffin-embedded samples from these same tumors (P = 0.0015), and a previously published NSCLC MFS dataset (P = 0.0015). The separation between high and low metastasis signature scores was higher at 3 years (ΔMFS TGFβ-EMT = −28.6%; ΔMFS TGFβ-EMT_N = −25.2%) than at 5 years (ΔMFS TGFβ-EMT = −18.6%; ΔMFS TGFβ-EMT_N = −11.8%). In addition, the TGFβ-EMT signature correlated with whether the cancer had already metastasized or not at time of surgery in a colon cancer cohort. The results show that the TGFβ-EMT signature successfully discriminated lung cancer cell lines capable of undergoing EMT in response to TGFβ-1 and predicts MFS in lung adenocarcinomas. Thus, the TGFβ-EMT signature has the potential to be developed as a clinically relevant predictive biomarker, for example to identify those patients with resected early stage lung cancer who may benefit from adjuvant therapy.

trans-3-Methoxy-5-hydroxystilbene (MHS) from the rhizome of Alpinia nantonensis inhibits metastasis in human lung cancer cells

BACKGROUND

Alpinia nantoensis (Zingiberaceae) is an aromatic plant endemic to Taiwan, which is used as food flavoring and traditional herbal medicine. The biological activities of compounds isolated from this plant are rarely investigated.

PURPOSE

The present study was aimed to investigate the anti-metastatic potential of trans-3‑methoxy‑5-hydroxystilbene (MHS) a major stilbene isolated from the rhizomes of A. nantonensis.

METHODS

We investigated the anti-metastatic potential of MHS on human non-small cell lung carcinoma (A549) cell line using wound healing, trans-well, western blot, zymography and immunofluorescence assays.

RESULTS

Initial cytotoxicity assay showed that treatment with MHS did not exhibit cytotoxicity to A549 cells up to the concentration of 40 µM. Further in vitro wound healing and transwell chamber assays revealed that MHS significantly inhibited tumor cell migration in a dose-dependent manner, which is associated with inhibition of matrix mettalloprotinase-2 (MMP-2) and matrix mettalloprotinase-9 (MMP-9) at both enzyme and protein levels. The inhibition of MMPs activity by MHS was reasoned by suppression of their corresponding transcription factor, β-catenin as indicated by reduced levels of β-catenin in the nucleus. MHS also regulates epithelial-to-mesenchymal transition (EMT) by increasing E-cadherin and occludin as well as decreasing N-cadherin levels in A549 cells. Furthermore, pre-treatment with MHS significantly inhibited A549 cells migration and EMT in TGF-β induced A549 cells.

CONCLUSION

To the best of our knowledge, this is the first report demonstrating that MHS, a plant-derived stilbene has a promising ability to inhibit lung cancer cell metastasis in vitro.

Design of Large-Scale Reporter Construct Arrays for Dynamic, Live Cell Systems Biology

Dynamic systems biology aims to identify the molecular mechanisms governing cell fate decisions through the analysis of living cells. Large scale molecular information from living cells can be obtained from reporter constructs that provide activities for either individual transcription factors or multiple factors binding to the full promoter following CRISPR/Cas9 directed insertion of luciferase. In this report, we investigated the design criteria to obtain reporters that are specific and responsive to transcription factor (TF) binding and the integration of TF binding activity with genetic reporter activity. The design of TF reporters was investigated for the impact of consensus binding site spacing sequence and off-target binding on the reporter sensitivity using a library of 25 SMAD3 activity reporters with spacers of random composition and length. A spacer was necessary to quantify activity changes after TGFβ stimulation. TF binding site prediction algorithms (BEEML, FIMO and DeepBind) were used to predict off-target binding, and nonresponsiveness to a SMAD3 reporter was correlated with a predicted competitive binding of constitutively active p53. The network of activity of the SMAD3 reporter was inferred from measurements of TF reporter library, and connected with large-scale genetic reporter activity measurements. The integration of TF and genetic reporters identified the major hubs directing responses to TGFβ, and this method provided a systems-level algorithm to investigate cell signaling.

Scleraxis regulates Twist1 and Snai1 expression in the epithelial-to-mesenchymal transition

Numerous physiological and pathological events, from organ development to cancer and fibrosis, are characterized by an epithelial-to-mesenchymal transition (EMT), whereby adherent epithelial cells convert to migratory mesenchymal cells. During cardiac development, proepicardial organ epithelial cells undergo EMT to generate fibroblasts. Subsequent stress or damage induces further phenotype conversion of fibroblasts to myofibroblasts, causing fibrosis via synthesis of an excessive extracellular matrix. We have previously shown that the transcription factor scleraxis is both sufficient and necessary for the conversion of cardiac fibroblasts to myofibroblasts and found that scleraxis knockout reduced cardiac fibroblast numbers by 50%, possibly via EMT attenuation. Scleraxis induced expression of the EMT transcriptional regulators Twist1 and Snai1 via an unknown mechanism. Here, we report that scleraxis binds to E-box consensus sequences within the Twist1 and Snai1 promoters to transactivate these genes directly. Scleraxis upregulates expression of both genes in A549 epithelial cells and in cardiac myofibroblasts. Transforming growth factor-β induces EMT, fibrosis, and scleraxis expression, and we found that transforming growth factor-β-mediated upregulation of Twist1 and Snai1 completely depends on the presence of scleraxis. Snai1 knockdown upregulated the epithelial marker E-cadherin; however, this effect was lost after scleraxis overexpression, suggesting that scleraxis may repress E-cadherin expression. Together, these results indicate that scleraxis can regulate EMT via direct transactivation of the Twist1 and Snai1 genes. Given the role of scleraxis in also driving the myofibroblast phenotype, scleraxis appears to be a critical controller of fibroblast genesis and fate in the myocardium and thus may play key roles in wound healing and fibrosis.

NEW & NOTEWORTHY The molecular mechanism by which the transcription factor scleraxis mediates Twist1 and Snai1 gene expression was determined. These results reveal a novel means of transcriptional regulation of epithelial-to-mesenchymal transition and demonstrate that transforming growth factor-β-mediated epithelial-to-mesenchymal transition is dependent on scleraxis, providing a potential target for controlling this process.

Leptin induces epithelial-to-mesenchymal transition via activation of the ERK signaling pathway in lung cancer cells

Previous studies revealed that leptin induces the growth and proliferation and inhibits the apoptosis of lung cancer cells. However, the effect of leptin on epithelial-to-mesenchymal transition (EMT) is not yet clear. In the present study, the effect of leptin on EMT was investigated as well as its underlying mechanisms in A549 cells. The ability of leptin to induce EMT was investigated by microscopic examination and western blotting. The impacts of leptin on cell migration, invasion and tumorigenesis were evaluated by wound healing, Transwell and colony formation assays, respectively. It was demonstrated that leptin induced EMT-associated morphological changes, namely a decrease in cell-cell contact and a more elongated morphological shape. Leptin decreased the expression levels of epithelial phenotype markers E-cadherin and keratin, increased the expression of mesenchymal phenotype marker Vimentin, and raised the expression of EMT-induced transcription factor ZEB-1. In addition, leptin activated the extracellular signal regulated kinase (ERK) signaling pathway and did not affect the activation of the protein kinase B signaling pathway in A549 cells. Leptin also promoted EMT-induced migration, invasion and tumorigenesis in vitro in A549 cells. The present study provides evidence that leptin induced EMT via the activation of the ERK signaling pathway and increased EMT-induced tumor phenotypes in lung cancer cells. These findings suggest that leptin may be a promising target for lung cancer treatment through the regulation of EMT.

Human alveolar epithelial cells type II are capable of TGFβ-dependent epithelial-mesenchymal-transition and collagen-synthesis

Background

The origin of collagen-producing cells in lung fibrosis is unclear. The involvement of embryonic signaling pathways has been acknowledged and trans-differentiation of epithelial cells is discussed critically. The work presented here investigates the role of TGFB in cytoskeleton remodeling and the expression of Epithelial-Mesenchymal-Transition markers by Alveolar Epithelial Cells Type II and tests the hypothesis if human alveolar epithelial cells are capable of trans-differentiation and production of pro-fibrotic collagen.

Methods

Primary human alveolar epithelial cells type II were extracted from donor tissues and stimulated with TGFβ and a TGFβ-inhibitor. Transcriptome and pathway analyses as well as validation of results on protein level were conducted.

Results

A TGFβ-responsive fingerprint was found and investigated for mutual interactions. Interaction modules exhibited enrichment of genes that favor actin cytoskeleton remodeling, differentiation processes and collagen metabolism. Cross-validation of the TGFβ-responsive fingerprint in an independent IPF dataset revealed overlap of genes and supported the direction of regulated genes and TGFβ-specificity.

Conclusions

Primary human alveolar epithelial cells type II seem undergo a TGFβ-dependent phenotypic change, exhibit differential expression of EMT markers in vitro and acquire the potential to produce collagen.

Electronic supplementary material

The online version of this article (10.1186/s12931-018-0841-9) contains supplementary material, which is available to authorized users.

Toosendanin, a natural product, inhibited TGF-β1-induced epithelial-mesenchymal transition through ERK/Snail pathway

Epithelial-mesenchymal transition (EMT) plays important roles in the metastasis of solid tumors. In this study, the effect of toosendanin (TSN), a natural insecticide extracted from Melia toosendan Sieb et Zucc, on transforming growth factor-β1 (TGF-β1)-induced EMT was investigated. EMT was induced by TGF-β1 in A549 and H1975 lung cancer cells. The morphological alterations were observed with a microscopy. The protein expression and localization of EMT biomarkers were determined by Western blotting and immunofluorescence. The migration, invasion, and adhesion were determined by wound-healing, transwell, and adhesion assays. TGF-β1 treatment induced spindle-shaped alterations of cells, upregulation of N-cadherin, Vimentin, p-ERK1/2, and downregulation of E-cadherin. The abilities of migration, invasion, and adhesion were also enhanced. These effects were significantly reversed by TSN at very low concentration (<10 nM). Furthermore, silence Snail significantly reversed TGF-β1-induced EMT biomarkers. In addition, TGF-β1-induced phosphorylation of ERK1/2 without affecting p38 mitogen-activated protein kinases and Jun N-terminal kinase. PD98059 and U0126, inhibitors of ERK1/2, showed similar inhibitory effect to that of TSN. In summary, TSN significantly inhibited TGF-β1-induced EMT and migration, invasion, and adhesion through ERK/Snail pathway in lung cancer cells. This study provides novel anticancer effects and molecular mechanisms for TSN.

The A2B Adenosine Receptor Modulates the Epithelial- Mesenchymal Transition through the Balance of cAMP/PKA and MAPK/ERK Pathway Activation in Human Epithelial Lung Cells

The epithelial-mesenchymal transition (EMT) is a complex process in which cell phenotype switches from the epithelial to mesenchymal one. The deregulations of this process have been related with the occurrence of different diseases such as lung cancer and fibrosis. In the last decade, several efforts have been devoted in understanding the mechanisms that trigger and sustain this transition process. Adenosine is a purinergic signaling molecule that has been involved in the onset and progression of chronic lung diseases and cancer through the A_2B adenosine receptor subtype activation, too. However, the relationship between A_2BAR and EMT has not been investigated, yet. Herein, the A_2BAR characterization was carried out in human epithelial lung cells. Moreover, the effects of receptor activation on EMT were investigated in the absence and presence of transforming growth factor-beta (TGF-β1), which has been known to promote the transition. The A_2BAR activation alone decreased and increased the expression of epithelial markers (E-cadherin) and the mesenchymal one (Vimentin, N-cadherin), respectively, nevertheless a complete EMT was not observed. Surprisingly, the receptor activation counteracted the EMT induced by TGF-β1. Several intracellular pathways regulate the EMT: high levels of cAMP and ERK1/2 phosphorylation has been demonstrated to counteract and promote the transition, respectively. The A_2BAR stimulation was able to modulated these two pathways, cAMP/PKA and MAPK/ERK, shifting the fine balance toward activation or inhibition of EMT. In fact, using a selective PKA inhibitor, which blocks the cAMP pathway, the A_2BAR-mediated EMT promotion were exacerbated, and conversely the selective inhibition of MAPK/ERK counteracted the receptor-induced transition. These results highlighted the A_2BAR as one of the receptors involved in the modulation of EMT process. Nevertheless, its activation is not enough to trigger a complete transition, its ability to affect different intracellular pathways could represent a mechanism at the basis of EMT maintenance/inhibition based on the extracellular microenvironment. Despite further investigations are needed, herein for the first time the A_2BAR has been related to the EMT process, and therefore to the different EMT-related pathologies.

MiR-9-5p promotes cell growth and metastasis in non-small cell lung cancer through the repression of TGFBR2

BACKGROUND

Increasing evidence indicates that the dysregulation of microRNAs (miRNAs) play critical roles tumor progression and metastasis, but very few papers had reported the function of miR-9-5p in lung cancer, especially in NSCLCs.

METHODS

In this study, we investigated the role of miR-9-5p in non-small cell lung cancers (NSCLCs). MiR-9-5p level were analyzed in 62 clinical NSCLC lung tissue samples and adjacent normal lung tissues by RT-PCR. The target of miR-9-5p was predicted by TargetScan and luciferase reporter assay was used to verify the binding site of miR-9-5p on TGFBR2 mRNA. MTT assay, wound healing assay and invasion assay were performed in both miR-5p inhibitor transfected A549 and miR-5p mimic transfected SK-MES-1 cells. To further investigate whether TGFBR2 is the major target of miR-9-5p, we used TGFBR2 siRNA to transfect A549 and SK-MES-1 cells with miR-9-5p inhibitor or miR-9-5p mimic transfection. Western blot were then used to analyze TGFBR2, p-smad2 and p-smad3 protein expressions after transfection.

RESULTS

Results indicated that NSCLC patients' tissues had a significantly higher expression of miR-9-5p compared to adjacent normal lung tissues. MiR-9-5p mimic transfection promoted proliferation, metastasis and invasion abilities in both A549 and SK-MES-1 cells. Conversely, miR-9-5p inhibitor transfection showed the decreased abilities of these cells. Luciferase reporter assay indicated that TGFBR2 is a direct target of miR-9-5p and the up-regulation of TGFBR2 suppressed cell proliferation, metastasis and invasion. The knock down of TGFBR2 abrogated the effect of miR-9-5p in down-regulating p-smad2 and p-smad3 expressions, which indicated that TGFBR2 is the major target of miR-9-5p in NSCLC cells.

CONCLUSIONS

Our finding indicated that miR-9-5p promotes the proliferation, metastasis and invasion of NSCLC cells by down-regulating TGFBR2 expression.

Sialidase inhibitors attenuate pulmonary fibrosis in a mouse model

Fibrosis involves increasing amounts of scar tissue appearing in a tissue, but what drives this is unclear. In fibrotic lesions in human and mouse lungs, we found extensive desialylation of glycoconjugates, and upregulation of sialidases. The fibrosis-associated cytokine TGF-β1 upregulates sialidases in human airway epithelium cells, lung fibroblasts, and immune system cells. Conversely, addition of sialidases to human peripheral blood mononuclear cells induces accumulation of extracellular TGF-β1, forming what appears to be a sialidase - TGF-β1 - sialidase positive feedback loop. Monocyte-derived cells called fibrocytes also activate fibroblasts, and we found that sialidases potentiate fibrocyte differentiation. A sialylated glycoprotein called serum amyloid P (SAP) inhibits fibrocyte differentiation, and sialidases attenuate SAP function. Injections of the sialidase inhibitors DANA and oseltamivir (Tamiflu) starting either 1 day or 10 days after bleomycin strongly attenuate pulmonary fibrosis in the mouse bleomycin model, and by breaking the feedback loop, cause a downregulation of sialidase and TGF-β1 accumulation. Together, these results suggest that a positive feedback loop involving sialidases potentiates fibrosis, and suggest that sialidase inhibitors could be useful for the treatment of fibrosis.

OLA1 contributes to epithelial-mesenchymal transition in lung cancer by modulating the GSK3β/snail/E-cadherin signaling

Obg-like ATPase 1 (OLA1) belongs to the Obg family of P-loop NTPases, and may serve as a "molecular switch" regulating multiple cellular processes. Aberrant expression of OLA1 has been observed in several human malignancies. However, the role of OLA1 in cancer progression remains poorly understood. In this study, we used the Kaplan-Meier plotter search tool to show that increased expression of OLA1 mRNA was significantly associated with shorter overall survival in lung cancer patients. By immunohistochemical analysis we discovered that levels of OLA1 protein in lung cancer tissues were positively correlated with TNM stage and lymph node metastasis, but negatively correlated with the epithelial-mesenchymal transition (EMT) marker E-cadherin. Knockdown of OLA1 in a lung adenocarcinoma cell line rendered the cells more resistant to TGF-β-induced EMT and the accompanied repression of E-cadherin. Furthermore, our results demonstrated that OLA1 is a GSK3β-interacting protein and inhibits GSK3β activity by mediating its Ser9 phosphorylation. During EMT, OLA1 plays an important role in suppressing the GSK3β-mediated degradation of Snail protein, which in turn promotes downregulation of E-cadherin. These data suggest that OLA1 contributes to EMT by modulating the GSK3β/Snail/E-cadherin signaling, and its overexpression is associated with clinical progression and poor survival in lung cancer patients.

Methotrexate-Induced Epithelial-Mesenchymal Transition in the Alveolar Epithelial Cell Line A549

PURPOSE

Methotrexate (MTX) therapy of certain cancers and rheumatoid arthritis often induces serious interstitial lung complications including pulmonary fibrosis. In this study, we investigated the epithelial-mesenchymal transition (EMT) induced by MTX and by transforming growth factor (TGF)-β1 in the human alveolar epithelial cell line A549 in order to develop new strategies for the prevention of EMT.

METHODS

First, we examined the effect of TGF-β1 and MTX on cell morphology and the expression of EMT-related mRNAs in A549 cells. Then, the effects of SB431542 (SB), a potent inhibitor of TGF-β receptor kinase, and a neutralizing antibody for TGF-β1 on the phenotypic changes of A549 cells induced by TGF-β1 and MTX were examined.

RESULTS

After incubation with TGF-β1 and MTX, the mRNA expression of epithelial markers such as cytokeratin 19 was reduced, while that of mesenchymal markers such as α-smooth muscle actin was increased. SB suppressed the development of morphological changes and partially rescued alterations in mRNA expression of EMT markers induced by MTX. In addition, the enhancement of SMAD2 phosphorylation by MTX was also prevented by SB. On the other hand, EMT-related changes induced by MTX were not affected by a neutralizing antibody for TGF-β1.

CONCLUSION

We have demonstrated that phenotypic changes of A549 cells induced by MTX are partly mediated by a TGF-β1-related intracellular signaling pathway, although TGF-β1 itself is not directly involved in this process.

Nanoroughened adhesion-based capture of circulating tumor cells with heterogeneous expression and metastatic characteristics

BACKGROUND

Circulating tumor cells (CTCs) have shown prognostic relevance in many cancer types. However, the majority of current CTC capture methods rely on positive selection techniques that require a priori knowledge about the surface protein expression of disseminated CTCs, which are known to be a dynamic population.

METHODS

We developed a microfluidic CTC capture chip that incorporated a nanoroughened glass substrate for capturing CTCs from blood samples. Our CTC capture chip utilized the differential adhesion preference of cancer cells to nanoroughened etched glass surfaces as compared to normal blood cells and thus did not depend on the physical size or surface protein expression of CTCs.

RESULTS

The microfluidic CTC capture chip was able to achieve a superior capture yield for both epithelial cell adhesion molecule positive (EpCAM+) and EpCAM- cancer cells in blood samples. Additionally, the microfluidic CTC chip captured CTCs undergoing transforming growth factor beta-induced epithelial-to-mesenchymal transition (TGF-β-induced EMT) with dynamically down-regulated EpCAM expression. In a mouse model of human breast cancer using EpCAM positive and negative cell lines, the number of CTCs captured correlated positively with the size of the primary tumor and was independent of their EpCAM expression. Furthermore, in a syngeneic mouse model of lung cancer using cell lines with differential metastasis capability, CTCs were captured from all mice with detectable primary tumors independent of the cell lines' metastatic ability.

CONCLUSIONS

The microfluidic CTC capture chip using a novel nanoroughened glass substrate is broadly applicable to capturing heterogeneous CTC populations of clinical interest independent of their surface marker expression and metastatic propensity. We were able to capture CTCs from a non-metastatic lung cancer model, demonstrating the potential of the chip to collect the entirety of CTC populations including subgroups of distinct biological and phenotypical properties. Further exploration of the biological potential of metastatic and presumably non-metastatic CTCs captured using the microfluidic chip will yield insights into their relevant differences and their effects on tumor progression and cancer outcomes.

Bleomycin (BLM) Induces Epithelial-to-Mesenchymal Transition in Cultured A549 Cells via the TGF-β/Smad Signaling Pathway

The epithelial-to-mesenchymal transition (EMT) is a crucial cellular event in wound healing, tissue repair, and cancer progression in adult tissues, with the interactions with numerous signals. In this study, we aimed to determine whether bleomycin (BLM), an agent that causes pulmonary fibrosis, induces the EMT of the alveolar epithelial cell line A549 and investigated the possible mechanisms. We examined the EMT involved changes in cell morphology, isoform switching of the fibroblast growth factor receptor 2 (FGFR2) by alternative splicing, and expression of the phenotypic markers including E-cadherin, vimentin, and α-SMA using RT-PCR, Western blotting, and immunofluorescence assays. A TGF-β/Smad inhibitor was used to determine whether coculture with BLM would inhibit the EMT of A549 cells. The results showed that BLM induced the EMT of A549 cells possibly via the TGF-β/Smad signaling pathway, evident from the decrease in the expression of E-cadherin and increase in the expression on vimentin.

Transforming growth factor beta 1 induced endothelin-1 release is peroxisome proliferator-activated receptor gamma dependent in A549 cells

Background

Endothelin-1 (ET-1) is involved in pulmonary vascular remodeling. The aim of this study was to investigate the biochemical interactions between PPAR-γ, TGF-β1 and ET-1 in vitro.

Methods

A549 cells were pre-treated with S2505 (10 μM), S2871 (10 μM) with/without SB203580 (10 μM) for 60 min following 2 h treatment with 10 ng/mL TGF-β1. A549 cells were also transfected with positive or negative PPAR-γ plasmids for comparison. RT-PCR, ELISA, western blotting and confocal laser scanning microscopy (CLSM) were used to measure the relevant expression of mRNA, protein, mediators of pathways and nuclear factor translocation.

Results

SB203580 inhibited TGF-β1 induced ET-1 expression in A549 cells. S2871 decreased PPAR-γ mRNA and increase TGF-β1-induced ET-1 expression. S2871 increased phosphorylation of p38 MAPK and Smad2. Cells transfected with PPAR-γ negative plasmid increased TGF-β1 induced ET-1 expression, and increased the expression of phospho-p38 MAPK and phospho-Smad2. S2505 increased PPAR-γ mRNA expression, suppressed the increased TGF-β1-induced expression of ET-1. S2505 inhibited TGF-β1 induced phosphorylation of p38 MAPK and Smad2, also the nuclear translocation of Smad2. Cells transfected with PPAR-γ positive plasmid reduced TGF-β1-induced ET-1 expression, and inhibited the expression of phospho-p38 MAPK and phospho-Smad2.

Conclusions

TGF-β1 induced release of endothelin-1 is PPAR-γ dependent in cultured A549 cells.

Cucurbitacin B inhibits the stemness and metastatic abilities of NSCLC via downregulation of canonical Wnt/β-catenin signaling axis

Lack of effective anti-metastatic drugs creates a major hurdle for metastatic lung cancer therapy. For successful lung cancer treatment, there is a strong need of newer therapeutics with metastasis-inhibitory potential. In the present study, we determined the anti-metastatic and anti-angiogenic potential of a natural plant triterpenoid, Cucurbitacin B (CuB) against non-small cell lung cancer (NSCLC) both in vitro and in vivo. CuB demonstrated a strong anti-migratory and anti-invasive ability against metastatic NSCLC at nanomolar concentrations. CuB also showed significant tumor angiogenesis-inhibitory effects as evidenced by the inhibition of migratory, invasive and tube-forming capacities of human umbilical vein endothelial cells. CuB-mediated inhibition of angiogenesis was validated by the inhibition of pre-existing vasculature in chick embryo chorio-allantoic membrane and matrigel plugs. Similarly, CuB inhibited the migratory behavior of TGF-β1-induced experimental EMT model. The CuB-mediated inhibition of metastasis and angiogenesis was attributable to the downregulation of Wnt/β-catenin signaling axis, validated by siRNA-knockdown of Wnt3 and Wnt3a. The CuB-mediated downregulation of Wnt/β-catenin signaling was also validated using 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-induced lung tumorigenesis model in vivo. Collectively, our findings suggest that CuB inhibited the metastatic abilities of NSCLC through the inhibition of Wnt/β-catenin signaling axis.

Inhibition of Plasminogen Activator Inhibitor-1 Attenuates Transforming Growth Factor-β-Dependent Epithelial Mesenchymal Transition and Differentiation of Fibroblasts to Myofibroblasts

Transforming growth factor-β (TGF-β) is central during the pathogenesis of pulmonary fibrosis, in which the plasminogen activator inhibitor-1 (PAI-1) also has an established role. TGF-β is also known to be the strongest inducer of PAI-1. To investigate the link between PAI-1 and TGF-β in fibrotic processes, we evaluated the effect of SK-216, a PAI-1-specific inhibitor, in TGF-β-dependent epithelial-mesenchymal transition (EMT) and fibroblast to myofibroblast differentiation. In human alveolar epithelial A549 cells, treatment with TGF-β induced EMT, whereas co-treatment with SK-216 attenuated the occurrence of EMT. The inhibition of TGF-β-induced EMT by SK-216 was also confirmed in the experiment using murine epithelial LA-4 cells. Blocking EMT by SK-216 inhibited TGF-β-induced endogenous production of PAI-1 and TGF-β in A549 cells as well. These effects of SK-216 were not likely mediated by suppressing either Smad or ERK pathways. Using human lung fibroblast MRC-5 cells, we demonstrated that SK-216 inhibited TGF-β-dependent differentiation of fibroblasts to myofibroblasts. We also observed this inhibition by SK-216 in human primary lung fibroblasts. Following these in vitro results, we tested oral administration of SK-216 into mice injected intratracheally with bleomycin. We found that SK-216 reduced the degree of bleomycin-induced pulmonary fibrosis in mice. Although the precise mechanisms underlying the link between TGF-β and PAI-1 regarding fibrotic process were not determined, PAI-1 seems to act as a potent downstream effector on the pro-fibrotic property of TGF-β. In addition, inhibition of PAI-1 activity by a PAI-1 inhibitor exerts an antifibrotic effect even in vivo. These data suggest that targeting PAI-1 as a downstream effector of TGF-β could be a promising therapeutic strategy for pulmonary fibrosis.

Investigation of the origin of stromal and endothelial cells at the desmoplastic interface in xenograft tumor in mice

Carcinoma-associated fibroblasts found at the interface between a tumor and the normal stroma play several roles in the development of cancer, including cancer initiation, growth, and progression, thereby also affecting patient prognosis. Although recent studies have focused on carcinoma-associated fibroblasts as potential treatment targets, the origin of these fibroblasts remains unclear. One theory suggests that these cells arise from tumor cells undergoing the epithelial-mesenchymal transition, i.e., tumor cells transform into carcinoma-associated fibroblasts. Therefore, in this study, we aimed to elucidate the cellular origin of carcinoma-associated fibroblasts in a mouse xenograft model. Mice were transplanted with human lung cancer cells (H226 and A549 cells). After sacrifice, tumor masses and surrounding tissues were excised. Interestingly, the excised xenograft tissues contained a significant proportion of desmoplastic fibroblasts that exhibited strong expression of α-smooth muscle actin (SMA). Immunohistochemical staining with pan-cytokeratin, vimentin, β-catenin, E-cadherin, and CD34 showed no evidence of the epithelial-mesenchymal transition. Additional evaluation using dual-color silver in situ hybridization with dinitrophenyl-labeled human epidermal growth factor receptor 2 (HER2) and digoxigenin-labeled chromosome 17 centromere probes also showed similar results. In conclusion, our results revealed that the epithelial-mesenchymal transition may not occur in tumor xenograft models, regardless of evidence supporting this phenomenon in humans.

CXCL9 Regulates TGF-β1-Induced Epithelial to Mesenchymal Transition in Human Alveolar Epithelial Cells

Epithelial to mesenchymal cell transition (EMT), whereby fully differentiated epithelial cells transition to a mesenchymal phenotype, has been implicated in the pathogenesis of idiopathic pulmonary fibrosis (IPF). CXCR3 and its ligands are recognized to play a protective role in pulmonary fibrosis. In this study, we investigated the presence and extent of EMT and CXCR3 expression in human IPF surgical lung biopsies and assessed whether CXCR3 and its ligand CXCL9 modulate EMT in alveolar epithelial cells. Coexpression of the epithelial marker thyroid transcription factor-1 and the mesenchymal marker α-smooth muscle actin and CXCR3 expression was examined by immunohistochemical staining of IPF surgical lung biopsies. Epithelial and mesenchymal marker expression was examined by quantitative real-time PCR, Western blotting, and immunofluorescence in human alveolar epithelial (A549) cells treated with TGF-β1 and CXCL9, with Smad2, Smad3, and Smad7 expression and cellular localization examined by Western blotting. We found that significantly more cells were undergoing EMT in fibrotic versus normal areas of lung in IPF surgical lung biopsy samples. CXCR3 was expressed by type II pneumocytes and fibroblasts in fibrotic areas in close proximity to cells undergoing EMT. In vitro, CXCL9 abrogated TGF-β1-induced EMT. A decrease in TGF-β1-induced phosphorylation of Smad2 and Smad3 occurred with CXCL9 treatment. This was associated with increased shuttling of Smad7 from the nucleus to the cytoplasm where it inhibits Smad phosphorylation. This suggests a role for EMT in the pathogenesis of IPF and provides a novel mechanism for the inhibitory effects of CXCL9 on TGF-β1-induced EMT.

Bufalin inhibits TGF-β-induced epithelial-to-mesenchymal transition and migration in human lung cancer A549 cells by downregulating TGF-β receptors

The epithelial-to-mesenchymal transition (EMT) is a well-known prerequisite for cancer cells to acquire the migratory and invasive capacity, and to subsequently metastasize. Bufalin is one of the major active components of the traditional Chinese medicine Chan Su, and accumulating evidence has shown its anticancer effect in multipe types of cancer. However, the role of bufalin in transforming growth factor‑β (TGF‑β)‑induced EMT and migration remains unclear. In the present study, the effect of bufalin on TGF‑β‑induced EMT and migration was investigated in human lung cancer A549 cells. TGF‑β induced EMT in A549 cells and increased their migratory ability, which were markedly suppressed by bufalin. Additionally, TGF‑β‑induced upregulation of Twist2 and zinc finger E‑box binding homeobox 2 (ZEB2), as well as the phosphorylation of Smad2 and Smad3 were also inhibited by bufalin. However, the Smad‑independent signaling pathways were not affected. Further analysis showed that the TGF‑β receptor I (TβRI) and TGF‑β receptor II (TβRII) were downregulated in the presence of bufalin. Pretreatment with SB431542, a potent inhibitor of the phosphorylation of TβRI, significantly attenuated TGF‑β‑induced EMT, mimicking the effect of bufalin on A549 cells. Taken together, these results suggest that bufalin suppresses TGF-β-induced EMT and migration by downregulating TβRI and TβRII in A549 cells.

Suitable parameter choice on quantitative morphology of A549 cell in epithelial-mesenchymal transition

Evaluation of morphological changes in cells is an integral part of study on epithelial to mesenchymal transition (EMT), however, only a few papers reported the changes in quantitative parameters and no article compared different parameters for demanding better parameters. In the study, the purpose was to investigate suitable parameters for quantitative evaluation of EMT morphological changes. A549 human lung adenocarcinoma cell line was selected for the study. Some cells were stimulated by transforming growth factor-β1 (TGF-β1) for EMT, and other cells were as control without TGF-β1 stimulation. Subsequently, cells were placed in phase contrast microscope and three arbitrary fields were captured and saved with a personal computer. Using the tools of Photoshop software, some cells in an image were selected, segmented out and exchanged into unique hue, and other part in the image was shifted into another unique hue. The cells were calculated with 29 morphological parameters by Image Pro Plus software. A parameter between cells with or without TGF-β1 stimulation was compared statistically and nine parameters were significantly different between them. Receiver operating characteristic curve (ROC curve) of a parameter was described with SPSS software and F-test was used to compare two areas under the curves (AUCs) in Excel. Among them, roundness and radius ratio were the most AUCs and were significant higher than the other parameters. The results provided a new method with quantitative assessment of cell morphology during EMT, and found out two parameters, roundness and radius ratio, as suitable for quantification.

Cardamonin Suppresses TGF-β1-Induced Epithelial Mesenchymal Transition via Restoring Protein Phosphatase 2A Expression

Epithelial mesenchymal transition (EMT) is the first step in metastasis and implicated in the phenotype of cancer stem cells. Therefore, understanding and controlling EMT, are essential to the prevention and cure of metastasis. In the present study, we examined, by Western blot, reverse transcription polymerase chain reaction (RT-PCR), and confocal microscopy, the effects of cardamonin (CDN) on transforming growth factor-β1 (TGF-β1)-induced EMT of A549 lung adenocarcinoma cell lines. TGF-β1 induced expression of N-cadherin and decreased expression of E-cadherin. CDN suppressed N-cadherin expression and restored E-cadherin expression. Further, TGF-β1 induced migration and invasion of A549 cancer cells, which was suppressed by CDN. TGF-β1 induced c-Jun N-terminal kinase (JNK) activation during EMT, but CDN blocked it. Protein serine/threonine phosphatase 2A (PP2A) expression in A549 cancer cells was reduced by TGF-β1 but CDN restored it. The overall data suggested that CDN suppresses TGF-β1-induced EMT via PP2A restoration, making it a potential new drug candidate that controls metastasis.

Hyperoxia stimulates the transdifferentiation of type II alveolar epithelial cells in newborn rats

Supplemental oxygen treatment in preterm infants may cause bronchopulmonary dysplasia (BPD), which is characterized by alveolar simplification and vascular disorganization. Despite type II alveolar epithelial cell (AEC II) damage being reported previously, we found no decrease in the AEC II-specific marker, surfactant protein C (SP-C), in the BPD model in our previous study. We thus speculated that AEC II injury is not a unique mechanism of BPD-related pulmonary epithelial repair dysfunction and that abnormal transdifferentiation can exist. Newborn rats were randomly assigned to model (85% oxygen inhalation) and control groups (room air inhalation). Expressions of AEC I (aquaporin 5, T1α) and AEC II markers (SP-C, SP-B) were detected at three levels: 1) in intact lung tissue, 2) in AEC II isolated from rats in the two groups, and 3) in AEC II isolated from newborn rats, which were further cultured under either hyperoxic or normoxic conditions. In the model group, increased AEC I was observed at both the tissue and cell level, and markedly increased transdifferentiation was observed by immunofluorescent double staining. Transmission electron microscopy revealed morphological changes in alveolar epithelium such as damaged AECs, a fused air-blood barrier structure, and opened tight junctions in the model group. These findings indicate that transdifferentiation of AECs is not suppressed but rather is increased under hyperoxic treatment by compensation; however, such repair during injury cannot offset pulmonary epithelial air exchange and barrier dysfunction caused by structural damage to AECs.

Transcription factor glioma-associated oncogene homolog 1 is required for transforming growth factor-β1-induced epithelial-mesenchymal transition of non-small cell lung cancer cells

Epithelial-mesenchymal transition (EMT) is the process by which epithelial cells depolarize and acquire a mesenchymal phenotype, and is a common early step in the process of metastasis. Patients with lung cancer frequently already have distant metastases when they are diagnosed, highlighting the requirement for early and effective interventions to control metastatic disease. Transforming growth factor-β1 (TGF-β1) is able to induce EMT, however the molecular mechanism of this remains unclear. In the current study, TGF-β1 was reported to induce EMT and promote the migration of non-small cell lung cancer (NSCLC) cells. A notable observation was that EMT induction was accompanied by the upregulation of human glioma-associated oncogene homolog 1 (Gli1) mRNA and protein levels. Furthermore, Gli1 levels were depleted by small interfering RNA, and the Gli1 inhibitor GANT 61 attenuated the TGF-β1-mediated induction of EMT and cell migration. The results of the current study suggest that Gli1 regulates TGF-β1-induced EMT, which may provide a novel therapeutic target to inhibit metastasis in patients with NSCLC.

The kinase activity of the Ser/Thr kinase BUB1 promotes TGF-β signaling

Transforming growth factor-β (TGF-β) signaling regulates cell proliferation and differentiation, which contributes to development and disease. Upon binding TGF-β, the type I receptor (TGFBRI) binds TGFBRII, leading to the activation of the transcription factors SMAD2 and SMAD3. Using an RNA interference screen of the human kinome and a live-cell reporter for TGFBR activity, we identified the kinase BUB1 (budding uninhibited by benzimidazoles-1) as a key mediator of TGF-β signaling. BUB1 interacted with TGFBRI in the presence of TGF-β and promoted the heterodimerization of TGFBRI and TGFBRII. Additionally, BUB1 interacted with TGFBRII, suggesting the formation of a ternary complex. Knocking down BUB1 prevented the recruitment of SMAD3 to the receptor complex, the phosphorylation of SMAD2 and SMAD3 and their interaction with SMAD4, SMAD-dependent transcription, and TGF-β-mediated changes in cellular phenotype including epithelial-mesenchymal transition (EMT), migration, and invasion. Knockdown of BUB1 also impaired noncanonical TGF-β signaling mediated by the kinases AKT and p38 MAPK (mitogen-activated protein kinase). The ability of BUB1 to promote TGF-β signaling depended on the kinase activity of BUB1. A small-molecule inhibitor of the kinase activity of BUB1 (2OH-BNPP1) and a kinase-deficient mutant of BUB1 suppressed TGF-β signaling and formation of the ternary complex in various normal and cancer cell lines. 2OH-BNPP1 administration to mice bearing lung carcinoma xenografts reduced the amount of phosphorylated SMAD2 in tumor tissue. These findings indicated that BUB1 functions as a kinase in the TGF-β pathway in a role beyond its established function in cell cycle regulation and chromosome cohesion.

Cisplatin sensitivity is enhanced in non-small cell lung cancer cells by regulating epithelial-mesenchymal transition through inhibition of eukaryotic translation initiation factor 5A2

BACKGROUND

Epithelial-mesenchymal transition (EMT) has been believed to be related with chemotherapy resistance in non-small cell lung cancer (NSCLC). Recent studies have suggested eIF5A-2 may function as a proliferation-related oncogene in tumorigenic processes.

METHODS

We used cell viability assays, western blotting, immunofluorescence, transwell-matrigel invasion assay, wound-healing assay combined with GC7 (a novel eIF5A-2 inhibitor) treatment or siRNA interference to investigate the role of eIF5A-2 playing in NSCLC chemotherapy.

RESULTS

We found low concentrations of GC7 have little effect on NSCLC viability, but could enhance cisplatin cytotoxicity in NSCLC cells. GC7 also could reverse mesenchymal phenotype in NCI-H1299 and prevented A549 cells undergoing EMT after TGF-β1 inducement. eIF5A-2 knockdown resulted in EMT inhibition.

CONCLUSION

Our data indicated GC7 enhances cisplatin cytotoxicity and prevents the EMT in NSCLC cells by inhibiting eIF5A-2.

Epithelial-mesenchymal transitions in bronchopulmonary dysplasia of newborn rats

BACKGROUND

Bronchopulmonary dysplasia (BPD) is a major threat to the health of premature infants yet its pathogenesis is not fully understood. Epithelial-mesenchymal transition (EMT) of lung epithelial cells may lead to BPD.

OBJECTIVE

To investigate the potential occurrence of EMT in a newborn rat model of BPD.

METHODS

Newborn rats were exposed to a hyperoxic environment within 12 hr of birth. Lung tissue and isolated alveolar epithelial type II cells (AT2 cells) were collected on Days 1, 3, 7, 14, and 21 after hyperoxic exposure. Pathological changes in lung tissue, alveolar development, ultrastructural changes in AT2 cells, co-expression of surfactant associated surfactant protein C (SPC), and α-smooth muscle actin (α-SMA) were investigated. The relative expression of SPC, α-SMA, E-cadherin, and N-cadherin were investigated in lung tissue and isolated AT2 cells.

RESULTS

In lung tissue, alveolar development was attenuated from Day 7 onwards in the BPD model group; co-expression of SPC and α-SMA and ultrastructural changes typical of EMT were observed in AT2 cells from rats in the BPD group. SPC and α-SMA expression levels were higher in tissue samples from the BPD group than in control samples. Beginning on Day 7, evidence of a switch from E-cadherin to N-cadherin expression was observed in BPD lung tissue sample and in isolated AT2 cells.

CONCLUSION

EMT of AT2 cells occurred in the hyperoxia-induced newborn rat BPD model and resulted in attenuated alveolar development as a portion of the myofibroblasts accumulated in the lung originated from AT2 cells via EMT.

Redox processes inform multivariate transdifferentiation trajectories associated with TGFβ-induced epithelial-mesenchymal transition

Phenotype reprogramming during transforming growth factor β (TGFβ)-induced epithelial-mesenchymal transition (EMT) is an extensive and dynamic process, orchestrated by the integration of biological signaling across multiple time scales. As part of the numerous transcriptional changes necessary for EMT, TGFβ-initiated Smad3 signaling results in remodeling of the redox environment and decreased nucleophilic tone. Because Smad3 itself is susceptible to attenuated activity through antioxidants, the possibility of a positive feedback loop exists, albeit the time scales on which these mechanisms operate are quite different. We hypothesized that the decreased nucleophilic tone acquired during EMT promotes Smad3 signaling, enhancing acquisition and stabilization of the mesenchymal phenotype. Previous findings supporting such a mechanism were characterized independent of each other; we sought to investigate these relationships within a singular experimental context. In this study, we characterized multivariate representations of phenotype as they evolved over time, specifically measuring expression of epithelial/mesenchymal differentiation, redox regulators, and Smad transcription factors. In-cell Western (ICW) assays were developed to evaluate multivariate phenotype states as they developed during EMT. Principal component analysis (PCA) extracted anticorrelations between phospho-Smad3 (pSmad3) and Smad2/Smad4, which reflected a compensatory up-regulation of Smad2 and Smad4 following cessation of TGFβ signaling. Measuring transcript expression following EMT, we identified down-regulation of numerous antioxidant genes concomitant with up-regulation of NADPH oxidase 4 (NOX4) and multiple mesenchymal phenotype markers. TGFβ treatment increased CM-H2DCF-DA oxidation, decreased H2O2 degradation rates, and increased glutathione redox potential. Our findings suggest that the decreased nucleophilic tone during EMT coincides with the acquisition of a mesenchymal phenotype over too long a time scale to enable enhanced Smad3 phosphorylation during initiation of EMT. We further challenged the mesenchymal phenotype following EMT through antioxidant and TGFβ inhibitor treatments, which failed to induce a mesenchymal-epithelial transition (MET). Our characterization of multivariate phenotype dynamics during EMT indicates that the decrease in nucleophilic tone occurs alongside EMT; however, maintenance of the mesenchymal phenotype following EMT is independent of both the nascent redox state and the continuous TGFβ signaling.

Metabolic reprogramming during TGFβ1-induced epithelial-to-mesenchymal transition

Metastatic progression, including extravasation and micro-metastatic outgrowth, is the main cause of cancer patient death. Recent studies suggest that cancer cells reprogram their metabolism to support increased proliferation through increased glycolysis and biosynthetic activities, including lipogenesis pathways. However, metabolic changes during metastatic progression, including alterations in regulatory gene expression, remain undefined. We show that transforming growth factor beta 1 (TGFβ1) induced Epithelial-to-Mesenchymal Transition (EMT) is accompanied by coordinately reduced enzyme expression required to convert glucose into fatty acids, and concomitant enhanced respiration. Over-expressed Snail1, a transcription factor mediating TGFβ1-induced EMT, was sufficient to suppress carbohydrate-responsive-element-binding protein (ChREBP, a master lipogenic regulator), and fatty acid synthase (FASN), its effector lipogenic gene. Stable FASN knock-down was sufficient to induce EMT, stimulate migration and extravasation in vitro. FASN silencing enhanced lung metastasis and death in vivo. These data suggest that a metabolic transition that suppresses lipogenesis and favors energy production is an essential component of TGFβ1-induced EMT and metastasis.

Mesenchymal-transitioned cancer cells instigate the invasion of epithelial cancer cells through secretion of WNT3 and WNT5B

Although the heterogeneities of epithelial and mesenchymal-transitioned cancer cells are often observed within the tumor microenvironment, the biological significance of the interaction between epithelial cancer cells and mesenchymal-transitioned cancer cells is not yet understood. In this study, we show that the mesenchymal-transitioned cancer cells instigate the invasive ability and metastatic potential of the neighboring epithelial cancer cells in vitro and in vivo. We identify WNT3 and WNT5B as critical factors secreted from Transforming growth factor-induced mesenchymal cancer cells for instigating the epithelial cancer cell invasion along with the induction of secondary EMT phenotype. These results shed light on the significance of cancer heterogeneity and the interaction between epithelial and mesenchymal-transitioned cancer cells within the tumor microenvironment in promoting metastatic disease through the WNT-dependent mechanism.