A SNAIL1-SMAD3/4 transcriptional repressor complex promotes TGF-beta mediated epithelial-mesenchymal transition

Snail and kidney fibrosis

Snail family zinc finger 1 (SNAI1) is a transcription factor expressed during renal embryogenesis, and re-expressed in various settings of acute kidney injury (AKI). Subjected to tight regulation, SNAI1 controls major biological processes responsible for renal fibrogenesis, including mesenchymal reprogramming of tubular epithelial cells, shutdown of fatty acid metabolism, cell cycle arrest and inflammation of the microenvironment surrounding tubular epithelial cells. The present review describes in detail the interactions of SNAI1 with AKI-associated signalling pathways. We also discuss how this central factor has been iteratively (and promisingly) targeted in a number of animal models in order to prevent or slow down renal fibrogenesis.

Mutual regulation between miR-21 and the TGFβ/Smad signaling pathway in human bronchial fibroblasts promotes airway remodeling

OBJECTIVE

Airway remodeling is an important pathological feature of asthma. Excessive deposition of extracellular matrix (e.g., collagen) secreted from fibroblasts is a major factor contributing to airway remodeling. Currently, the mechanism by which collagen continues to be oversynthesized in the airway remains unclear. In this study, we investigated the role of the microRNA-21 (miR-21) and TGFβ/Smad signaling pathway in human bronchial fibroblasts (HBFs), and explored the regulatory mechanism of airway remodeling.

METHODS

HBFs were cultured in vitro and treated with the transforming growth factor β (TGFβ), receptor inhibitor (SB431542), and TGFβ1. miR-21 and Smad7 overexpressing lentiviruses, as well as an miR-21 interfering lentivirus were constructed and transfected into HBFs. Western blotting was used to determine the expression of airway remodeling-related proteins and proteins in the TGFβ/Smad signaling pathway. miR-21 expression was measured by quantitative real-time PCR.

RESULTS

The high expression of miR-21 induced by TGFβ1 was reduced following the treatment with the SB431542 in HBFs. Smad7 overexpression inhibited the elevated expression of the COL I protein induced by miR-21 overexpression in HBFs. Inhibiting miR-21 expression upregulated the level of Smad7 protein, thus reducing the expression of airway remodeling-related proteins induced by TGFβ1 stimulation in HBFs.

CONCLUSIONS

TGFβ1 can induce miR-21 expression in HBFs through the TGFβ/Smad signaling pathway to promote airway remodeling. miR-21 downregulates Smad7, activates the TGFβ/Smad signaling pathway, and promotes airway remodeling. Mutual regulation between miR-21 and the TGFβ/Smad signaling pathway in HBFs promotes airway remodeling.

Exosome-Mediated Transfer of Cancer Cell Resistance to Antiestrogen Drugs

Exosomes are small vesicles which are produced by the cells and released into the surrounding space. They can transfer biomolecules into recipient cells. The main goal of the work was to study the exosome involvement in the cell transfer of hormonal resistance. The experiments were performed on in vitro cultured estrogen-dependent MCF-7 breast cancer cells and MCF-7 sublines resistant to SERM tamoxifen and/or biguanide metformin, which exerts its anti-proliferative effect, at least in a part, via the suppression of estrogen machinery. The exosomes were purified by differential ultracentrifugation, cell response to tamoxifen was determined by MTT test, and the level and activity of signaling proteins were determined by Western blot and reporter analysis. We found that the treatment of the parent MCF-7 cells with exosomes from the resistant cells within 14 days lead to the partial resistance of the MCF-7 cells to antiestrogen drugs. The primary resistant cells and the cells with the exosome-induced resistance were characterized with these common features: decrease in ERα activity and parallel activation of Akt and AP-1, NF-κB, and SNAIL1 transcriptional factors. In general, we evaluate the established results as the evidence of the possible exosome involvement in the transferring of the hormone/metformin resistance in breast cancer cells.

Epithelial-mesenchymal transition in breast epithelial cells treated with cadmium and the role of Snail

Epidemiological and experimental studies have implicated cadmium (Cd) with breast cancer. In breast epithelial MCF10A and MDA-MB-231 cells, Cd has been shown to promote cell growth. The present study examined whether Cd also promotes epithelial-mesenchymal transition (EMT), a hallmark of cancer progression. Human breast epithelial cells consisting of non-cancerous MCF10A, non-metastatic HCC 1937 and HCC 38, and metastatic MDA-MB-231 were treated with 1 or 3 μM Cd for 4 weeks. The MCF10A epithelial cells switched to a more mesenchymal-like morphology, which was accompanied by a decrease in the epithelial marker E-cadherin and an increase in the mesenchymal markers N-cadherin and vimentin. In both non-metastatic HCC 1937 and HCC 38 cells, treatment with Cd decreased the epithelial marker claudin-1. In addition, E-cadherin also decreased in the HCC 1937 cells. Even the mesenchymal-like MDA-MB-231 cells exhibited an increase in the mesenchymal marker vimentin. These changes indicated that prolonged treatment with Cd resulted in EMT in both normal and cancer-derived breast epithelial cells. Furthermore, both the MCF10A and MDA-MB-231 cells labeled with Zcad, a dual sensor for tracking EMT, demonstrated a decrease in the epithelial marker E-cadherin and an increase in the mesenchymal marker ZEB-1. Treatment of cells with Cd significantly increased the level of Snail, a transcription factor involved in the regulation of EMT. However, the Cd-induced Snail expression was completely abolished by actinomycin D. Luciferase reporter assay indicated that the expression of Snail was regulated by Cd at the promotor level. Snail was essential for Cd-induced promotion of EMT in the MDA-MB-231 cells, as knockdown of Snail expression blocked Cd-induced cell migration. Together, these results indicate that Cd promotes EMT in breast epithelial cells and does so by modulating the transcription of Snail.

Face morphogenesis is promoted by Pbx-dependent EMT via regulation of Snail1 during frontonasal prominence fusion

Human cleft lip with or without cleft palate (CL/P) is a common craniofacial abnormality caused by impaired fusion of the facial prominences. We have previously reported that, in the mouse embryo, epithelial apoptosis mediates fusion at the seam where the prominences coalesce. Here, we show that apoptosis alone is not sufficient to remove the epithelial layers. We observed morphological changes in the seam epithelia, intermingling of cells of epithelial descent into the mesenchyme and molecular signatures of epithelial-mesenchymal transition (EMT). Utilizing mouse lines with cephalic epithelium-specific Pbx loss exhibiting CL/P, we demonstrate that these cellular behaviors are Pbx dependent, as is the transcriptional regulation of the EMT driver Snail1. Furthermore, in the embryo, the majority of epithelial cells expressing high levels of Snail1 do not undergo apoptosis. Pbx1 loss- and gain-of-function in a tractable epithelial culture system revealed that Pbx1 is both necessary and sufficient for EMT induction. This study establishes that Pbx-dependent EMT programs mediate murine upper lip/primary palate morphogenesis and fusion via regulation of Snail1. Of note, the EMT signatures observed in the embryo are mirrored in the epithelial culture system.

Epithelial-mesenchymal transition in Crohn's disease

Crohn's disease (CD) is often accompanied by the complications of intestinal strictures and fistulas. These complications remain obstacles in CD treatment. In recent years, the importance of epithelial-mesenchymal transition in the pathogenesis of CD-associated fistulas and intestinal fibrosis has become apparent. Epithelial-mesenchymal transition refers to a dynamic change, wherein epithelial cells lose their polarity and adherence and acquire migratory function and fibroblast features. During formation of CD-associated fistulas, intestinal epithelial cells dislocate from the basement membrane and migrate to the lining of the fistula tracts, where they convert into transitional cells as a compensatory response under the insufficient wound healing condition. In CD-associated intestinal fibrosis, epithelial-mesenchymal transition may serve as a source of new fibroblasts and consequently lead to overproduction of extracellular matrix. In this review, we present current knowledge of epithelial-mesenchymal transition and its role in the pathogenesis of CD in order to highlight new therapy targets for the associated complications.

TGF-β1 alters esophageal epithelial barrier function by attenuation of claudin-7 in eosinophilic esophagitis

Barrier dysfunction has been implicated in the pathophysiology of eosinophilic esophagitis (EoE). Transforming growth factor-β1 (TGF-β1), a potent pleiotropic molecule, is increased in EoE; however, no study has evaluated its influence on esophageal epithelial barrier. We hypothesized that TGF-β1 regulates barrier dysfunction in EoE. We aimed to determine the role of TGF-β1 in the epithelial barrier in models of EoE. To examine the impact of TGF-β1 on esophageal barrier, immortalized human esophageal epithelial (EPC2-hTERT) cells were exposed to TGF-β1 during the three-dimensional air-liquid interface (3D-ALI) model in vitro. TGF-β1 exposure diminished EPC2-hTERT barrier function as measured by transepithelial electrical resistance (TEER) and 3 kDa Fluorescein isothiocyanate dextran paracellular flux (FITC Flux), and hematoxylin and eosin (H&E) assessment revealed prominent cellular separation. In analysis of epithelial barrier molecules, TGF-β1 led to the specific reduction in expression of the tight-junction molecule, claudin-7 (CLDN7), and this was prevented by TGF-β-receptor I inhibitor. Short hairpin ribonucleic acid (shRNA)-mediated CLDN7 knockdown diminished epithelial barrier function, whereas CLDN7 overexpression resulted in protection from TGF-β1-mediated barrier dysfunction. In pediatric EoE biopsies CLDN7 expression was decreased and altered localization was observed with immunofluorescence analysis, and the TGF-β1 downstream transcription factor, phosphorylated SMAD2/3 (pSMAD2/3), was increased. Our data suggest that TGF-β1 participates in esophageal epithelial barrier dysfunction through CLDN7 dysregulation.

AGO1 may influence the prognosis of hepatocellular carcinoma through TGF-β pathway

AGO1 is a major component of RNA-induced silencing complexes and plays a crucial role in solid tumors. The aim of our study was to investigate AGO1 functions in hepatocellular carcinoma (HCC). Using small interfering RNA, AGO1 functions were investigated in HCCLM3 cell lines. Cell proliferation, immigration, and invasion significantly decreased after AGO1 depletion using MTT, wound-healing, and transwell assay. The associated proteins in the epithelial–mesenchymal transition (EMT) and the activation of its signal pathways were measured using western blot. After AGO1 depleted, increased E-cadherin and decreased N-cadherin, Vimentin, Snail, and Zeb1 were founded. In its upstream pathway, the phosphorylation of ERK1/2(Thr202/Tyr204), Smad2(S425/250/255), and Smad4 were significantly inhibited. Meanwhile, inhibitor of ERK1/2(LY3214996) significantly inhibited the growth and migration of the AGO1 cells. The nuclear importing of Smad4 was blocked and furthermore, the transcription of Snail was also influenced for the decrease of combination between Smad4 and the promotor region of Snail. After Snail was overexpressed, the invasion of HCCLM3 cells was significantly rescued. Immunohistochemistry in tissue microarrays consisting of 200 HCC patients was used to analyze the associations between AGO1 expression and prognosis. Intratumoral AGO1 expression was an independent risk factor for overall survival (P = 0.008) and recurrence-free survival (P < 0.001). In conclusion, AGO1 may promote HCC metastasis through TGF-β pathway, and AGO1 may be a reliable prognostic factor in HCC.

Sorafenib inhibits macrophage-mediated epithelial-mesenchymal transition in hepatocellular carcinoma

Tumor-associated macrophages, crucial components of the microenvironment in hepatocellular carcinoma, hamper anti-cancer immune responses. The aim of the present study was to investigate the effect of sorafenib on the formation of the tumor microenvironment, especially the relationship between polarized macrophages and hepatocytes. Macrophage infiltration was reduced in patients with hepatocellular carcinoma who were treated with sorafenib. In vitro, sorafenib abolished polarized macrophage-induced epithelial mesenchymal transition (EMT) and migration of hepatocellular carcinoma cells but not normal hepatocytes. Moreover, sorafenib attenuated HGF secretion in polarized macrophages, and decreased plasma HGF in patients with hepatocellular carcinoma. Additionally, sorafenib abolished the polarized macrophage-induced activation of the HGF receptor Met in hepatocellular carcinoma cells. Our findings suggest that sorafenib inhibits polarized macrophage-induced EMT in hepatocellular carcinoma cells via the HGF-Met signaling pathway. These results contribute to our understanding of the immunological mechanisms that underlie the protective effects of sorafenib in hepatocellular carcinoma therapy.

Antrodia cinnamomea mycelial fermentation broth inhibits the epithelial-mesenchymal transition of human esophageal adenocarcinoma cancer cells

Esophageal cancer is associated with a high mortality rate and easy metastasis. The aim of this study is to investigate the effect of the bio-product Antrodia cinnamomea mycelial fermentation broth (AC-MFB) on the epithelial mesenchymal transition (EMT) of human esophageal cancer cells and the molecular mechanisms underlying these effects. Transforming growth factor β (TGF-β) was used to induce EMT in human esophageal BE3 cancer cells. Changes in cell morphology and migration potential were examined. The expression of E-cadherin, N-cadherin, vimentin, and other transcriptional factors was studied by western blot assay. The results showed that AC-MFB was not only able to upregulate the expression of Ecadherin and attenuate the TGF-β-induced overexpression of vimentin and N-cadherin, but it also reversed the TGF-β-induced changes in cell morphology from polygonal to spindle-shaped and delayed the migration potential of BE3 cells. Furthermore, AC-MFB treatment was able to inhibit the expression levels of both Twist and Twist1. Overall, AC-MFB was able to inhibit the EMT of esophageal cancer BE3 cells, which was accompanied by Twist and Twist1 downregulation.

Smad4 and epithelial-mesenchymal transition proteins in colorectal carcinoma: an immunohistochemical study

Epithelial-mesenchymal transition (EMT) plays an important role in cancer metastasis. During EMT, tumor cells acquire the capacity to migrate and invade the stroma. Activation of the transforming growth factor-b (TGF-b) signaling pathway is of major importance for the initiation of EMT. Smad4, an essential protein of this pathway, is known to complex with multiple transcription factors (e.g. Snail-1, Slug, Twist-1), in various types of cancer, promoting the repression or activation of target genes. The role of Smad4 in colorectal cancer (CRC) is not straightforward so far. In the present study forty eight resected CRC tumor specimens were immunohistochemically examined in order to assess the expression of Smad4 and its association with E-cadherin, Snail-1, Slug, Twist-1 protein expression and with various pathological parameters. Smad4 was found to be positively correlated with Snail-1, Slug and Twist-1 expression (p < 0.001). On the other hand it was negatively correlated with the expression of E-cadherin (p < 0.001). Furthermore, lymphatic invasion could be clearly associated with Smad4 expression, a finding complying with the metastatic ability of EMT cells. In conclusion, Smad4 could be considered as a central component of EMT transition in human colorectal cancer that combines with transcriptional factors to reduce E-cadherin and alter the expression of the epithelial phenotype.

The morphological and molecular mechanisms of epithelial/endothelial-to-mesenchymal transition and its involvement in atherosclerosis

Cell transdifferentiation occurs during cardiovascular development or remodeling either as a pathologic feature in the progression of disease or as a response to injury. Endothelial-to-Mesenchymal Transition (EndMT) is a process that is classified as a specialized form of Epithelial-to-Mesenchymal Transition (EMT), in which epithelial cells lose their epithelial characteristics and gain a mesenchymal phenotype. During transdifferentiation, cells lose both cell-cell contacts and their attachment to the basement membrane. Subsequently, the shape of the cells changes from a cuboidal to an elongated shape. A rearrangement of actin filaments facilitates the cells to become motile and prime their migration into the underlying tissue. EMT is a key process during embryonic development, wound healing and tissue regeneration, but has also been implicated in pathophysiological processes, such organ fibrosis and tumor metastases. EndMT has been associated with additional pathophysiological processes in cardiovascular related diseases, including atherosclerosis. Recent studies prove a significant role for EndMT in the progression and destabilization of atherosclerotic plaques, as a consequence of EndMT-derived fibroblast infiltration and the increased secretion of matrix metalloproteinase respectively. In this review we will discuss the essential molecular and morphological mechanisms of EMT and EndMT, along with their common denominators and key differences. Finally, we will discuss the role of EMT/EndMT in developmental and pathophysiological processes, focusing on the potential role of EndMT in atherosclerosis in more depth.

Safer approaches to therapeutic modulation of TGF-β signaling for respiratory disease

The transforming growth factor (TGF)-β cytokines play a central role in development and progression of chronic respiratory diseases. TGF-β overexpression in chronic inflammation, remodeling, fibrotic process and susceptibility to viral infection is established in the most prevalent chronic respiratory diseases including asthma, COPD, lung cancer and idiopathic pulmonary fibrosis. Despite the overwhelming burden of respiratory diseases in the world, new pharmacological therapies have been limited in impact. Although TGF-β inhibition as a therapeutic strategy carries great expectations, the constraints in avoiding compromising the beneficial pleiotropic effects of TGF-β, including the anti-proliferative and immune suppressive effects, have limited the development of effective pharmacological modulators. In this review, we focus on the pathways subserving deleterious and beneficial TGF-β effects to identify strategies for selective modulation of more distal signaling pathways that may result in agents with improved safety/efficacy profiles. Adverse effects of TGF-β inhibitors in respiratory clinical trials are comprehensively reviewed, including those of the marketed TGF-β modulators, pirfenidone and nintedanib. Precise modulation of TGF-β signaling may result in new safer therapies for chronic respiratory diseases.

Snail regulates BMP and TGFβ pathways to control the differentiation status of glioma-initiating cells

Glioblastoma multiforme is a brain malignancy characterized by high heterogeneity, invasiveness, and resistance to current therapies, attributes related to the occurrence of glioma stem cells (GSCs). Transforming growth factor β (TGFβ) promotes self-renewal and bone morphogenetic protein (BMP) induces differentiation of GSCs. BMP7 induces the transcription factor Snail to promote astrocytic differentiation in GSCs and suppress tumor growth in vivo. We demonstrate that Snail represses stemness in GSCs. Snail interacts with SMAD signaling mediators, generates a positive feedback loop of BMP signaling and transcriptionally represses the TGFB1 gene, decreasing TGFβ1 signaling activity. Exogenous TGFβ1 counteracts Snail function in vitro, and in vivo promotes proliferation and re-expression of Nestin, confirming the importance of TGFB1 gene repression by Snail. In conclusion, novel insight highlights mechanisms whereby Snail differentially regulates the activity of the opposing BMP and TGFβ pathways, thus promoting an astrocytic fate switch and repressing stemness in GSCs.

HIPK2 polymorphisms rs2058265, rs6464214, and rs7456421 were associated with kidney stone disease in Chinese males not females

BACKGROUND AND AIM

Recent studies have shown that genetic factors are involved in the development of kidney stone disease (KSD). A case-control association analysis was performed to investigate the association between homeodomain-interacting protein kinase 2 (HIPK2; OMIM *606868) polymorphisms and KSD.

METHODS

A total of 890 KSD patients and 920 healthy subjects were analyzed. Polymorphisms were genotyped using SNPscanTM high-throughput SNP classification technology. The genotypic and allelic frequencies in KSD patients and healthy individuals were analyzed using a Chi-square test.

RESULTS

The genotype and allele distributions of the three polymorphisms (rs2058265, rs6464214, and rs7456421 in HIPK2) displayed strong associations with KSD in males (rs2058265: odds ratio [OR] 2.480,95%confidence interval [CI] 1.205-5.106, p = 0.014; rs6464214: OR 2.466, 95%CI 1.198-5.078, p = 0.014; rs7456421: OR 2.846, 95%CI 1.362-5.947, p = 0.005; perallele: r2058265T, OR 1.357, 95%CI 1.073-1.715, p = 0.011; rs6464214G, OR 1.340, 95%CI 1.060-1.693, p = 0.014; rs7456421C, OR 1.356, 95%CI 1.073-1.713, p = 0.011). Patients carrying the T allele of rs2058265, the G allele of rs6464214, or the C allele of rs7456421 showed higher systolic blood pressure, creatinine, and uric acid levels compared with wild-genotype individuals after adjusting for age, gender, and body mass index (p < 0.005).

CONCLUSION

The association of HIPK2 gene polymorphisms with KSD was only observed in males but not in females. HIPK2 gene polymorphisms were also involved in the changes of KSD-related metabolic traits.

Transforming growth factor-β in stem cells and tissue homeostasis

TGF-β 1-3 are unique multi-functional growth factors that are only expressed in mammals, and mainly secreted and stored as a latent complex in the extracellular matrix (ECM). The biological functions of TGF-β in adults can only be delivered after ligand activation, mostly in response to environmental perturbations. Although involved in multiple biological and pathological processes of the human body, the exact roles of TGF-β in maintaining stem cells and tissue homeostasis have not been well-documented until recent advances, which delineate their functions in a given context. Our recent findings, along with data reported by others, have clearly shown that temporal and spatial activation of TGF-β is involved in the recruitment of stem/progenitor cell participation in tissue regeneration/remodeling process, whereas sustained abnormalities in TGF-β ligand activation, regardless of genetic or environmental origin, will inevitably disrupt the normal physiology and lead to pathobiology of major diseases. Modulation of TGF-β signaling with different approaches has proven effective pre-clinically in the treatment of multiple pathologies such as sclerosis/fibrosis, tumor metastasis, osteoarthritis, and immune disorders. Thus, further elucidation of the mechanisms by which TGF-β is activated in different tissues/organs and how targeted cells respond in a context-dependent way can likely be translated with clinical benefits in the management of a broad range of diseases with the involvement of TGF-β.

The role of TGF-β/SMAD4 signaling in cancer

Transforming growth factor β (TGF-β) signaling pathway plays important roles in many biological processes, including cell growth, differentiation, apoptosis, migration, as well as cancer initiation and progression. SMAD4, which serves as the central mediator of TGF-β signaling, is specifically inactivated in over half of pancreatic duct adenocarcinoma, and varying degrees in many other types of cancers. In the past two decades, multiple studies have revealed that SMAD4 loss on its own does not initiate tumor formation, but can promote tumor progression initiated by other genes, such as KRAS activation in pancreatic duct adenocarcinoma and APC inactivation in colorectal cancer. In other cases, such as skin cancer, loss of SMAD4 plays an important initiating role by disrupting DNA damage response and repair mechanisms and enhance genomic instability, suggesting its distinct roles in different types of tumors. This review lists SMAD4 mutations in various types of cancer and summarizes recent advances on SMAD4 with focuses on the function, signaling pathway, and the possibility of SMAD4 as a prognostic indicator.

TGF-β Family Signaling in Epithelial Differentiation and Epithelial-Mesenchymal Transition

Epithelia exist in the animal body since the onset of embryonic development; they generate tissue barriers and specify organs and glands. Through epithelial-mesenchymal transitions (EMTs), epithelia generate mesenchymal cells that form new tissues and promote healing or disease manifestation when epithelial homeostasis is challenged physiologically or pathologically. Transforming growth factor-βs (TGF-βs), activins, bone morphogenetic proteins (BMPs), and growth and differentiation factors (GDFs) have been implicated in the regulation of epithelial differentiation. These TGF-β family ligands are expressed and secreted at sites where the epithelium interacts with the mesenchyme and provide paracrine queues from the mesenchyme to the neighboring epithelium, helping the specification of differentiated epithelial cell types within an organ. TGF-β ligands signal via Smads and cooperating kinase pathways and control the expression or activities of key transcription factors that promote either epithelial differentiation or mesenchymal transitions. In this review, we discuss evidence that illustrates how TGF-β family ligands contribute to epithelial differentiation and induce mesenchymal transitions, by focusing on the embryonic ectoderm and tissues that form the external mammalian body lining.

Lipopolysaccharide Mediates the Destruction of Intercellular Tight Junction among Renal Tubular Epithelial Cells via RhoT1/SMAD-4/JAM-3 Pathway

Background: The morbidity of sepsis induced acute kidney injury remains unacceptable high and the mechanisms of that disease remains unclear. For urine backleak and intercellular tight junction among tubular epithelial cells (TECs) destruction often occur during sepsis induced acute kidney injury, we examined whether lipopolysaccharide could damage intercellular tight junction among TECs and associated mechanisms in our present study. Methods: HK-2 cells were cultured, transfected with different SiRNAs and stimulated with LPS and PYR-41. Transepithelial Permeability Assay and Transepithelial Electrical Resistance Assay were used to evaluate intercellular tight junction destruction and Western Blot and Immunofluorescence were used to evaluate proteins expression. Results: Transepithelial Permeability increased significantly (P<0.05) and Transepithelial Electrical Resistance reduced remarkably (P<0.05) of the monolayer TECs stimulated with LPS. The expression of JAM-3 and RhoT1 decreased significantly (P<0.05) in TECs stimulated with LPS, while the level of SMAD-4 increased significantly (P<0.05). Downregulation of the expression of SMAD-4 with RNA interference could increase the expression of JAM-3 in LPS treated TECs. Moreover, upregulation of RhoT1 level by decreased the degradation of RhoT1 could decrease the expression of SMAD-4 and increase the JAM-3 level in TECs treated with LPS, while downregulation of RhoT1 level with RNA interference had the opposite effects. Conclusion: LPS mediates intercellular tight junction destruction among TECs and RhoT1/SMAD-4/JAM-3 is a pivotal pathway to mediate the phenomenon.

Enterolactone modulates the ERK/NF-κB/Snail signaling pathway in triple-negative breast cancer cell line MDA-MB-231 to revert the TGF-β-induced epithelial-mesenchymal transition

Objective

Triple-negative breast cancer (TNBC) is highly metastatic, and there is an urgent unmet need to develop novel therapeutic strategies leading to the new drug discoveries against metastasis. The transforming growth factor-β (TGF-β) is known to promote the invasive and migratory potential of breast cancer cells through induction of epithelial-mesenchymal transition (EMT) via the ERK/NF-κB/Snail signaling pathway, leading to breast cancer metastasis. Targeting this pathway to revert the EMT would be an attractive, novel therapeutic strategy to halt breast cancer metastasis.

Methods

Effects of enterolactone (EL) on the cell cycle and apoptosis were investigated using flow cytometry and a cleaved caspase-3 enzyme-linked immunosorbent assay (ELISA), respectively. Effects of TGF-β induction and EL treatment on the functional malignancy of MDA-MB-231 breast cancer cells were investigated using migration and chemo-invasion assays. The effects of EL on EMT markers and the ERK/NF-κB/Snail signaling pathway after TGF-β induction were studied using confocal microscopy, quantitative reverse transcription polymerase chain reaction (qRT-PCR), Western blot, and flow cytometry.

Results

Herein, we report that EL exhibits a significant antimetastatic effect on MDA-MB-231 cells by almost reverting the TGF-β-induced EMT in vitro. EL downregulates the mesenchymal markers N-cadherin and vimentin, and upregulates the epithelial markers E-cadherin and occludin. It represses actin stress fiber formation via inhibition of mitogen-activated protein kinase p-38 (MAPK-p38) and cluster of differentiation 44 (CD44). EL also suppresses ERK-1/2, NF-κB, and Snail at the mRNA and protein levels.

Conclusions

Briefly, EL was found to inhibit TGF-β-induced EMT by blocking the ERK/NF-κB/Snail signaling pathway, which is a promising target for breast cancer metastasis therapy.

Smad3-mediated recruitment of the methyltransferase SETDB1/ESET controls Snail1 expression and epithelial-mesenchymal transition

During epithelial-mesenchymal transition (EMT), reprogramming of gene expression is accompanied by histone modifications. Whether EMT-promoting signaling directs functional changes in histone methylation has not been established. We show here that the histone lysine methyltransferase SETDB1 represses EMT and that, during TGF-β-induced EMT, cells attenuate SETDB1 expression to relieve this inhibition. SETDB1 also controls stem cell generation, cancer cell motility, invasion, metastatic dissemination, as well as sensitivity to certain cancer drugs. These functions may explain the correlation of breast cancer patient survival with SETDB1 expression. At the molecular level, TGF-β induces SETDB1 recruitment by Smad3, to repress Smad3/4-activated transcription of SNAI1, encoding the EMT "master" transcription factor SNAIL1. Suppression of SNAIL1-mediated gene reprogramming by SETDB1 occurs through H3K9 methylation at the SNAI1 gene that represses its H3K9 acetylation imposed by activated Smad3/4 complexes. SETDB1 therefore defines a TGF-β-regulated balance between histone methylation and acetylation that controls EMT.

Diverse pathways of epithelial mesenchymal transition related with cancer progression and metastasis and potential effects of endocrine disrupting chemicals on epithelial mesenchymal transition process

Endocrine disrupting chemicals (EDCs) are natural or synthetic compounds that interfere with normal functions of natural hormones in the body, leading to a disruption of the endocrine system. Specifically, EDCs have the potential to cause formation of several hormone-dependent cancers, including breast, ovarian, and prostate cancers. Epithelial mesenchymal transition (EMT) process by which epithelial cells lose their cell polarity and cell-cell adhesion and acquire mesenchymal phenotype is closely associated with malignant transformation and the initiation of cancer metastasis. As a key epithelial marker responsible for adherens junction, E-cadherin enables the cells to maintain epithelial phenotypes. EMT event is induced by E-cadherin loss which can be carried out by many transcription factors (TFs), including Snail, Slug, ZEB1, ZEB2, Kruppel-like factor 8 (KLF8), and Twist. N-cadherin, fibronectin, and vimentin are mesenchymal markers needed for cellular migration. The EMT process is regulated by several signaling pathways mediated by transforming growth factor β (TGF-β), Wnt-β-catenin, Notch, Hedgehog, and receptor tyrosine kinases. In the present article, we reviewed the current understanding of cancer progression effects of synthetic chemical EDCs such as bisphenol A (BPA), phthalates, tetrachlorodibenzo-p-dioxin (TCDD), and triclosan by focusing their roles in the EMT process. Collectively, the majority of previous studies revealed that BPA, phthalates, TCDD, and triclosan have the potential to induce cancer metastasis through regulating EMT markers and migration via several signaling pathways associated with the EMT program. Therefore, it is considered that the exposure to these EDCs can increase the risk aggravating the disease for the patients suffering cancer and that more regulations about the use of these EDCs are needed.

Prognostic Prediction of Oral Squamous Cell Carcinoma by E-Cadherin and N-Cadherin Expression in Overall Cells in Tumor Nests or Tumor Cells at the Invasive Front

Epithelial-mesenchymal transition (EMT) is a significant process in the invasion and metastasis of cancers including oral squamous cell carcinoma (OSCC), and the cadherin switch has been identified as one of the hallmarks of EMT. The aim of the present study was to evaluate the significance of the cadherin switch in the prognosis of OSCC and generate a model for prognostic predictions. Seventy-six biopsy and/or initial surgical specimens from OSCC patients were immunohistochemically analyzed for the expression of E-cadherin and N-cadherin in either overall OSCC cells in tumor nests or in OSCC cells at the invasive front. Among 76 OSCC cases, overall OSCC cells in tumor nests were negative for the expression of E-cadherin in 10 cases and positive for that of N-cadherin in 53 cases. Among 10 cases negative for the expression of E-cadherin, 4 cases were positive for that of N-cadherin. In OSCC cells at the invasive front, the expression of E-cadherin was negative in 62 cases, while that of N-cadherin was positive in 39 cases. Among 62 cases negative for the expression of E-cadherin, 33 cases were positive for that of N-cadherin. A logistic regression analysis showed that a model using the evaluation of N-cadherin expression in overall OSCC cells in tumor nests with a cut-off point of 70 years old was the best fit model. These results suggest that N-cadherin has significant value in prognostic predictions for OSCC patients.

LINE-1 couples EMT programming with acquisition of oncogenic phenotypes in human bronchial epithelial cells

Although several lines of evidence have established the central role of epithelial-to-mesenchymal-transition (EMT) in malignant progression of non-small cell lung cancers (NSCLCs), the molecular events connecting EMT to malignancy remain poorly understood. This study presents evidence that Long Interspersed Nuclear Element-1 (LINE-1) retrotransposon couples EMT programming with malignancy in human bronchial epithelial cells (BEAS-2B). This conclusion is supported by studies showing that: 1) activation of EMT programming by TGF-β1 increases LINE-1 mRNAs and protein; 2) the lung carcinogen benzo(a)pyrene coregulates TGF-β1 and LINE-1 mRNAs, with LINE-1 positioned downstream of TGF-β1 signaling; and, 3) forced expression of LINE-1 in BEAS-2B cells recapitulates EMT programming and induces malignant phenotypes and tumorigenesis in vivo. These findings identify a TGFβ1-LINE-1 axis as a critical effector pathway that can be targeted for the development of precision therapies during malignant progression of intractable NSCLCs.

MicroRNA-92b inhibits epithelial-mesenchymal transition-induced migration and invasion by targeting Smad3 in nasopharyngeal cancer

Increasing studies reports that aberrant miRNAs contribute to nasopharyngeal carcinoma (NPC) development and progression. However, the role of miR-92b in NPC remains unclear. In present research, we found that a reduced miR-92b expression in NPC tissues and cell lines. The clinical data showed that the down-regulated miR-92b expression was obviously associated with adverse prognostic characteristic. Furthermore, we confirmed that miR-92b was a novel independent prognostic symbol for predicting 5-year survival of NPC patients. MiR-92b overexpression inhibited cell migration, invasion and EMT progress, while down-regulated miR-92b reversed the effect. Besides, miR-92b could modulate Smad3 by directly binding to its 3’-UTR. In clinical samples of NPC, miR-92b inversely correlated with Smad3. Alternation of Smad3 expression at least partially abrogated the migration, invasion and EMT progress of miR-92b on NPC cells. In summary, our results indicated that miR-92b functioned as a tumor suppressor gene in regulating the EMT and metastasis of NPC via targeting Smad3, and may represent a novel potential therapeutic target and prognostic marker for NPC.

Alterations of microRNAs throughout the malignant evolution of cutaneous squamous cell carcinoma: the role of miR-497 in epithelial to mesenchymal transition of keratinocytes

Skin carcinogenesis is known to be a multi-step process with several stages along its malignant evolution. We hypothesized that transformation of normal epidermis to cutaneous squamous cell carcinoma (cSCC) is causally linked to alterations in microRNAs (miRNA) expression. For this end we decided to evaluate their alterations in the pathologic states ending in cSCC. Total RNA was extracted from formalin fixed paraffin embedded biopsies of five stages along the malignant evolution of keratinocytes towards cSCC: Normal epidermis, solar elastosis, actinic keratosis KIN1-2, advanced actinic keratosis KIN3 and well-differentiated cSCC. Next-generation small RNA sequencing was performed. We found that 18 miRNAs are overexpressed and 28 miRNAs are underexpressed in cSCC compared to normal epidermis. miR-424, miR-320, miR-222 and miR-15a showed the highest fold change among the overexpressed miRNAs. And miR-100, miR-101 and miR-497 showed the highest fold change among the underexpressed miRNAs. Heat map of hierarchical clustering analysis of significantly changed miRNAs and principle component analysis disclosed that the most prominent change in miRNAs expression occurred in the switch from 'early' stages; normal epidermis, solar elastosis and early actinic keratosis to the 'late' stages of epidermal carcinogenesis; late actinic keratosis and cSCC. We found several miRNAs with 'stage specific' alterations while others display a clear 'gradual', either progressive increase or decrease in expression along the malignant evolution of keratinocytes. The observed alterations focused in miRNAs involved in the regulation of AKT/mTOR or in those involved in epithelial to mesenchymal transition. We chose to concentrate on the evaluation of the molecular role of miR-497. We found that it induces reversion of epithelial to mesenchymal transition. We proved that SERPINE-1 is its biochemical target. The present study allows us to further study the pathways that are regulated by miRNAs along the malignant evolution of keratinocytes towards cSCC.

β-catenin, Twist and Snail: Transcriptional regulation of EMT in smokers and COPD, and relation to airflow obstruction

COPD is characterised by poorly reversible airflow obstruction usually due to cigarette smoking. The transcription factor clusters of β-catenin/Snail1/Twist has been implicated in the process of epithelial mesenchymal transition (EMT), an intermediate between smoking and airway fibrosis, and indeed lung cancer. We have investigated expression of these transcription factors and their "cellular localization" in bronchoscopic airway biopsies from patients with COPD, and in smoking and non-smoking controls. An immune-histochemical study compared cellular protein expression of β-catenin, Snail1 and Twist, in these subject groups in 3 large airways compartment: epithelium (basal region), reticular basement membrane (Rbm) and underlying lamina propria (LP). β-catenin and Snail1 expression was generally high in all subjects throughout the airway wall with marked cytoplasmic to nuclear shift in COPD (P < 0.01). Twist expression was generalised in the epithelium in normal but become more basal and nuclear with smoking (P < 0.05). In addition, β-catenin and Snail1 expression, and to lesser extent of Twist, was related to airflow obstruction and to expression of a canonical EMT biomarker (S100A4). The β-catenin-Snail1-Twist transcription factor cluster is up-regulated and nuclear translocated in smokers and COPD, and their expression is closely related to both EMT activity and airway obstruction.

Pro-invasive properties of Snail1 are regulated by sumoylation in response to TGFβ stimulation in cancer

Transforming growth factor β (TGFβ) is a key regulator of epithelial-to-mesenchymal transition (EMT) during embryogenesis and in tumors. The effect of TGFβ, on ΕΜΤ, is conveyed by induction of the pro-invasive transcription factor Snail1. In this study, we report that TGFβ stimulates Snail1 sumoylation in aggressive prostate, breast and lung cancer cells. Sumoylation of Snail1 lysine residue 234 confers its transcriptional activity, inducing the expression of classical EMT genes, as well as TGFβ receptor I (TβRI) and the transcriptional repressor Hes1. Mutation of Snail1 lysine residue 234 to arginine (K234R) abolished sumoylation of Snail1, as well as its migratory and invasive properties in human prostate cancer cells. An increased immunohistochemical expression of Snail1, Sumo1, TβRI, Hes1, and c-Jun was observed in aggressive prostate cancer tissues, consistent with their functional roles in tumorigenesis.

Blood-testis barrier integrity depends on Pin1 expression in Sertoli cells

The conformation and function of a subset of serine and threonine-phosphorylated proteins are regulated by the prolyl isomerase Pin1 through isomerization of phosphorylated Ser/Thr-Pro bonds. Pin1 is intensely expressed in Sertoli cells, but its function in this post mitotic cell remains unclear. Our aim was to investigate the role of Pin1 in the Sertoli cells. Lack of Pin1 caused disruption of the blood-testis barrier. We next investigated if the activin pathways in the Sertoli cells were affected by lack of Pin1 through immunostaining for Smad3 protein in testis tissue. Indeed, lack of Pin1 caused reduced Smad3 expression in the testis tissue, as well as a reduction in the level of N-Cadherin, a known target of Smad3. Pin1-/- testes express Sertoli cell marker mRNAs in a pattern similar to that seen in Smad3+/- mice, except for an increase in Wt1 expression. The resulting dysregulation of N-Cadherin, connexin 43, and Wt1 targets caused by lack of Pin1 might affect the mesenchymal-epithelial balance in the Sertoli cells and perturb the blood-testis barrier. The effect of Pin1 dosage in Sertoli cells might be useful in the study of toxicant-mediated infertility, gonadal cancer, and for designing male contraceptives.

Inhibition of CDK-mediated Smad3 phosphorylation reduces the Pin1-Smad3 interaction and aggressiveness of triple negative breast cancer cells

Triple negative breast cancer (TNBC) is a highly aggressive breast cancer subtype that lacks effective targeted therapies. Although TNBC is not defined by specific therapeutic targets, a subset of patients have tumors that overexpress cyclins. High cyclin D/E expression catalyzes CDK4/2 activity. In turn, CDK4/2 can non-canonically phosphorylate Smad3, a key TGFβ signaling intermediate, and this phosphorylation has been associated with the shift from tumor-suppressive to oncogenic TGFβ pathway action in breast oncogenesis. Additionally, CDK-mediated Smad3 phosphorylation facilitates an interaction between Smad3 and Pin1, a cis-trans isomerase that is also overexpressed in aggressive breast cancers. Treatment with CYC065, a CDK2/9 inhibitor, decreased non-canonical Smad3 phosphorylation and inhibited the Pin1-Smad3 interaction. We hypothesized that the interaction of Pin1 and Smad3, facilitated by CDK-mediated Smad3 phosphorylation, promotes TNBC cell aggressiveness. Inhibition of the Pin1-Smad3 interaction in TNBC cell lines, through depletion of Pin1 or CYC065 treatment, resulted in decreased cell migration/invasion and impeded the EMT program. Inhibition of CDK-mediated phosphorylation of Smad3 by mutagenesis also decreased cell migration, underscoring the importance of non-canonical CDK2 phosphorylation of Smad3 to enable cell motility. Pin1 depletion restored Smad3 protein levels and tumor-suppressive activity, suggesting that the Pin1-Smad3 interaction has a negative impact on canonical Smad3 action. Collectively, the data show that the Pin1-Smad3 interaction, facilitated by CDK-mediated Smad3 phosphorylation, is associated with oncogenic TGFβ signaling and breast cancer progression. Inhibition of this interaction with CYC065 treatment may provide an important therapeutic option for TNBC patients.

Epithelial-mesenchymal transition in cancer metastasis through the lymphatic system

It was already in the 18th century when the French surgeon LeDran first noted that breast cancer patients with spread of tumor cells to their axillary lymph nodes had a drastically worse prognosis than patients without spread (LeDran et al., ). Since then, metastatic spread of cancer cells to regional lymph nodes has been established as the most important prognostic factor in many types of cancer (Carter et al., ; Elston and Ellis, ). However, despite its clinical importance, lymph metastasis remains an underexplored area of tumor biology. Fundamental questions, such as when, how, and perhaps most importantly, why tumor cells disseminate through the lymphatic system, remain largely unanswered. Accordingly, no treatment strategies exist that specifically target lymph metastasis. The identification of epithelial-mesenchymal transition (EMT) as a mechanism, which allows cancer cells to dedifferentiate and acquire enhanced migratory and invasive properties, has been a game changer in cancer research. Conceptually, EMT provides an explanation for why epithelial cancers with poor differentiation status are generally more aggressive and prone to metastasize than more differentiated cancers. Inflammatory cytokines, such as TGF-β, which are produced and secreted by tumor-infiltrating immune cells, are potent inducers of EMT. Thus, reactivation of EMT also links cancer-related inflammation to invasive and metastatic disease. Recently, we found that breast cancer cells undergoing TGF-β-induced EMT acquire properties of immune cells allowing them to disseminate in a targeted fashion through the lymphatic system similar to activated dendritic cells during inflammation. Here, we review our current understanding of the mechanisms by which cancer cells spread through the lymphatic system and the links to inflammation and the immune system. We also emphasize how imaging techniques have the potential to further expand our knowledge of the mechanisms of lymph metastasis, and how lymph nodes serve as an interface between cancer and the immune system.

NF-κB Mediates Mesenchymal Transition, Remodeling, and Pulmonary Fibrosis in Response to Chronic Inflammation by Viral RNA Patterns

Airway remodeling is resultant of a complex multicellular response associated with a progressive decline of pulmonary function in patients with chronic airway disease. Here, repeated infections with respiratory viruses are linked with airway remodeling through largely unknown mechanisms. Although acute activation of the Toll-like receptor (TLR) 3 pathway by extracellular polyinosinic:polycytidylic acid (poly[I:C]) induces innate signaling through the NF-κB transcription factor in normal human small airway epithelial cells, prolonged (repetitive or tonic) poly(I:C) stimulation produces chronic stress fiber formation, mesenchymal transition, and activation of a fibrotic program. Chronic poly(I:C) stimulation enhanced the expression of core mesenchymal regulators Snail family zinc finger 1, zinc finger E-box binding homeobox, mesenchymal intermediate filaments (vimentin), and extracellular matrix proteins (fibronectin-1), and collagen 1A. This mesenchymal transition was prevented by silencing expression of NF-κB/RelA or administration of a small-molecule inhibitor of the IκB kinase, BMS345541. Acute poly(I:C) exposure in vivo induced profound neutrophilic airway inflammation. When administered repetitively, poly(I:C) resulted in enhanced fibrosis observed by lung micro-computed tomography, second harmonic generation microscopy of optically cleared lung tissue, and by immunohistochemistry. Epithelial flattening, expansion of the epithelial mesenchymal trophic unit, and enhanced Snail family zinc finger 1 and fibronectin 1 expression in airway epithelium were also observed. Repetitive poly(I:C)-induced airway remodeling, fibrosis, and epithelial-mesenchymal transition was inhibited by BMS345541 administration. Based on this novel model of viral inflammation-induced remodeling, we conclude that NF-κB is a major controller of epithelial-mesenchymal transition and pulmonary fibrosis, a finding that has potentially important relevance to airway remodeling produced by repetitive viral infections.

HMOX-1 inhibits TGF-β-induced epithelial-mesenchymal transition in the MCF-7 breast cancer cell line

Epithelial‑mesenchymal transition (EMT) is a key mechanism underlying metastatic breast cancer. Reactive oxygen species (ROS) play an important role in EMT. Heme oxygenase‑1 (HMOX‑1) can reduce oxidative stress. However, the effect of HMOX‑1 on the EMT process in breast cancer cells is unknown. We treated the MCF‑7 breast cancer cell line with the HMOX‑1 inducer hemin and observed that hemin induced HMOX‑1 expression and inhibited migration, invasion and ROS generation in transforming growth factor‑β (TGF‑β)‑treated MCF‑7 cells using quantitative RT‑qPCR, western blotting, wound‑healing and cell invasion assays as well as fluorescent probe DCFDA. Hemin inhibited TGF‑β‑induced EMT in the MCF‑7 cells, whereas HMOX‑1 siRNA attenuated the suppressive effect of hemin as determined by the expression and cellular distribution of selected EMT markers. In summary, our results revealed that hemin treatment increased HMOX‑1 expression and inhibited TGF‑β‑induced EMT in MCF‑7 cells.

Expression pattern and phosphorylation status of Smad2/3 in different subtypes of human first trimester trophoblast

INTRODUCTION

TGF-β superfamily members are thought to play a pivotal role in placental development and differentiation. However, their downstream effectors, the Smad transcription factors, have been poorly investigated in human trophoblasts.

METHODS

Expression and localisation of the canonical TGF-β targets Smad2/3 and their regulators (Smad4 and Smad7) were investigated in first trimester placenta and purified cytotrophoblast (CTB) subtypes using immunofluorescence, western blotting and qPCR. Canonical and non-canonical activation was analysed in nuclear/cytoplasmic extracts of trophoblast subtypes as well as in tissue sections using antibodies against Smad2/3, phosphorylated either at the C-terminus (pSmad2C/3C) or in their linker regions (pSmad2L/3L). Smad phosphorylation was also examined in differentiating extravillous trophoblasts (EVTs) in the absence or presence of decidual stromal cell (DSC)-conditioned medium.

RESULTS

Smad2, Smad4 and Smad7 protein were uniformly expressed between 6th and 12th week placentae and the different isolated CTB subtypes. Activated pSmad2L was mainly detected in nuclei and cytoplasm of villous CTBs, whereas pSmad2C was absent from these cells. In contrast, pSmad2C could be detected in the cytoplasm of cell column trophoblasts and in the cytoplasm/nuclei of EVTs. Smad3 and its phosphorylated forms pSmad3C and pSmad3L specifically localised to EVT nuclei. During EVT differentiation autocrine activation of pSmad2C/3C and pSmad3L was observed. DSC-conditioned medium further increased Smad2/3 phosphorylation in EVTs.

DISCUSSION

The lack of pSmad2C in villous CTBs suggests that other mitogens than TGF-β could promote Smad2 linker phosphorylation under homeostatic conditions. Whereas autocrine signalling activates Smad2/3 in differentiating EVTs, paracrine factors contribute to Smad phosphorylation in these cells.

A83-01 inhibits TGF-β-induced upregulation of Wnt3 and epithelial to mesenchymal transition in HER2-overexpressing breast cancer cells

PURPOSE

The aim of this study is to investigate the mechanisms of interactions between TGF-β and Wnt/β-catenin pathways that induce and regulate EMT and promote breast cancer cells to become resistant to treatment.

METHODS

The effect of TGF-β on Wnt/β-catenin signaling pathway was examined by using a human Wnt/β-catenin-regulated cDNA plate array and western blot analysis. The interaction of Twist at promoter of Wnt3 was examined by chromatin immunoprecipitation (ChIP) assay. Secreted Wnt3 level was determined by ELISA assay.

RESULTS

HER2-overexpressing breast cancer cells treated with TGF-β have a reduced response to trastuzumab and exhibited EMT-like phenotype. The TGF-β-induced EMT in HER2-cells was concordant with upregulation of Wnt3 and β-catenin pathways. The TGF-β-induced induction of Wnt3 during EMT was found to be Smad3-dependent. ChIP analysis identified occupancy of Twist at promoter region of Wnt3. Knock-down of Twist by shRNA confirmed the significance of Twist in response to TGF-β regulating Wnt3 during EMT. Subsequently, TGF-β-induced matrix metalloproteinases, MMP1, MMP7, MMP9, MMP26, Vascular endothelial growth factors (VEGF), and activation of Wnt/β-catenin signaling were repressed by the shRNA treatment. TGF-βR1 ALK5 kinase inhibitor, A83-01 can effectively prevent the TGF-β-induced Twist and Wnt3. Co-treating A83-01 and trastuzumab inhibited TGF-β-induced cell invasion significantly in both trastuzumab responsive and resistant cells.

CONCLUSIONS

Our data demonstrated an important interdependence between TGF-β and Wnt/β-catenin pathways inducing EMT in HER2-overexpressing breast cancer cells. Twist served as a linkage between the two pathways during TGF-β-induced EMT. A83-01 could inhibit the TGF-β-initiated pathway interactions and enhance HER2-cells response to trastuzumab treatment.

β-Catenin/CBP-Dependent Signaling Regulates TGF-β-Induced Epithelial to Mesenchymal Transition of Lens Epithelial Cells

Purpose

Transforming growth factor-β–induced epithelial–mesenchymal transition (EMT) is one of the main causes of posterior capsular opacification (PCO) or secondary cataract; however, the signaling events involved in TGF-β–induced PCO have not been fully characterized. Here, we focus on examining the role of β-catenin/cyclic AMP response element–binding protein (CREB)-binding protein (CBP) and β-catenin/T-cell factor (TCF)-dependent signaling in regulating cytoskeletal dynamics during TGF-β–induced EMT in lens epithelial explants.

Methods

Rat lens epithelial explants were cultured in medium M199 in the absence of serum. Explants were treated with TGF-β2 in the presence or absence of the β-catenin/CBP interaction inhibitor, ICG-001, or the β-catenin/TCF interaction inhibitor, PNU-74654. Western blot and immunofluorescence experiments were carried out and analyzed.

Results

An increase in the expression of fascin, an actin-bundling protein, was observed in the lens explants upon stimulation with TGF-β, and colocalized with F-actin filaments. Inhibition of β-catenin/CBP interactions, but not β-catenin/TCF interactions, led to a decrease in TGF-β–induced fascin and stress fiber formation, as well as a decrease in the expression of known markers of EMT, α-smooth muscle actin (α-SMA) and matrix metalloproteinase 9 (MMP9). In addition, inhibition of β-catenin/CBP–dependent signaling also prevented TGF-β–induced downregulation of epithelial cadherin (E-cadherin) in lens explants.

Conclusions

We show that β-catenin/CBP–dependent signaling regulates fascin, MMP9, and α-SMA expression during TGF-β–induced EMT. We demonstrate that β-catenin/CBP–dependent signaling is crucial for TGF-β–induced EMT in the lens.

Role of peptidylarginine deiminase 2 (PAD2) in mammary carcinoma cell migration

BACKGROUND

Penetration of the mammary gland basement membrane by cancer cells is a crucial first step in tumor invasion. Using a mouse model of ductal carcinoma in situ, we previously found that inhibition of peptidylarginine deiminase 2 (PAD2, aka PADI2) activity appears to maintain basement membrane integrity in xenograft tumors. The goal of this investigation was to gain insight into the mechanisms by which PAD2 mediates this process.

METHODS

For our study, we modulated PAD2 activity in mammary ductal carcinoma cells by lentiviral shRNA-mediated depletion, lentiviral-mediated PAD2 overexpression, or PAD inhibition and explored the effects of these treatments on changes in cell migration and cell morphology. We also used these PAD2-modulated cells to test whether PAD2 may be required for EGF-induced cell migration. To determine how PAD2 might promote tumor cell migration in vivo, we tested the effects of PAD2 inhibition on the expression of several cell migration mediators in MCF10DCIS.com xenograft tumors. In addition, we tested the effect of PAD2 inhibition on EGF-induced ductal invasion and elongation in primary mouse mammary organoids. Lastly, using a transgenic mouse model, we investigated the effects of PAD2 overexpression on mammary gland development.

RESULTS

Our results indicate that PAD2 depletion or inhibition suppresses cell migration and alters the morphology of MCF10DCIS.com cells. In addition, we found that PAD2 depletion suppresses the expression of the cytoskeletal regulatory proteins RhoA, Rac1, and Cdc42 and also promotes a mesenchymal to epithelial-like transition in tumor cells with an associated increase in the cell adhesion marker, E-cadherin. Our mammary gland organoid study found that inhibition of PAD2 activity suppresses EGF-induced ductal invasion. In vivo, we found that PAD2 overexpression causes hyperbranching in the developing mammary gland.

CONCLUSION

Together, these results suggest that PAD2 plays a critical role in breast cancer cell migration. Our findings that EGF treatment increases protein citrullination and that PAD2 inhibition blocks EGF-induced cell migration suggest that PAD2 likely functions within the EGF signaling pathway to mediate cell migration.

SMAD4 Loss Is Associated with Cetuximab Resistance and Induction of MAPK/JNK Activation in Head and Neck Cancer Cells

Purpose: We previously demonstrated an association between decreased SMAD4 expression and cetuximab resistance in head and neck squamous cell carcinoma (HNSCC). The purpose of this study was to further elucidate the clinical relevance of SMAD4 loss in HNSCC.Experimental Design: SMAD4 expression was assessed by IHC in 130 newly diagnosed and 43 patients with recurrent HNSCC. Correlative statistical analysis with clinicopathologic data was also performed. OncoFinder, a bioinformatics tool, was used to analyze molecular signaling in TCGA tumors with low or high SMAD4 mRNA levels. The role of SMAD4 was investigated by shRNA knockdown and gene reconstitution of HPV-negative HNSCC cell lines in vitro and in vivoResults: Our analysis revealed that SMAD4 loss was associated with an aggressive, HPV-negative, cetuximab-resistant phenotype. We found a signature of prosurvival and antiapoptotic pathways that were commonly dysregulated in SMAD4-low cases derived from TCGA-HNSCC dataset and an independent oral cavity squamous cell carcinoma (OSCC) cohort obtained from GEO. We show that SMAD4 depletion in an HNSCC cell line induces cetuximab resistance and results in worse survival in an orthotopic mouse model in vivo We implicate JNK and MAPK activation as mediators of cetuximab resistance and provide the foundation for the concomitant EGFR and JNK/MAPK inhibition as a potential strategy for overcoming cetuximab resistance in HNSCCs with SMAD4 loss.Conclusions: Our study demonstrates that loss of SMAD4 expression is a signature characterizing the cetuximab-resistant phenotype and suggests that SMAD4 expression may be a determinant of sensitivity/resistance to EGFR/MAPK or EGFR/JNK inhibition in HPV-negative HNSCC tumors. Clin Cancer Res; 23(17); 5162-75. ©2017 AACR.

Sirtuin 6 inhibits epithelial to mesenchymal transition during idiopathic pulmonary fibrosis via inactivating TGF-β1/Smad3 signaling

Sirt6 which is implicated in the control of aging, cancer, and metabolism, has been shown to have anti-fibrosis function in heart and liver. However, whether Sirt6 inhibits idiopathic pulmonary fibrosis remains elusive. Epithelial to mesenchymal transition has been found to be involved in the pathogenesis of idiopathic pulmonary fibrosis. In the present study, forced expression of Sirt6 significantly abrogated TGF-β1-induced epithelial to mesenchymal transition-like phenotype and cell behaviors in A549 cells. Additionally, activation of TGF-β1/Smad3 signaling pathway and binding of Smad3-Snail1 were ameliorated by overexpression of wild-type Sirt6 but not mutant Sirt6 (H133Y) without histone deacetylase activity. Meanwhile, upregulation of epithelial to mesenchymal transition-related transcription factors by TGF-β1 were also restored by overexpression of wild-type Sirt6 but not mutant Sirt6. Furthermore, in vivo study showed that lung targeted delivery of Sirt6 using adeno-associated virus injection blunted bleomycin-induced pulmonary epithelial to mesenchymal transition and fibrosis. Overall, our findings unravel that Sirt6 acts as a key modulator in epithelial to mesenchymal transition process, suggesting Sirt6 may be an attractive potential therapeutic target for idiopathic pulmonary fibrosis.

STIM1 and STIM2 differently regulate endogenous Ca2+ entry and promote TGF-β-induced EMT in breast cancer cells

The Ca²⁺ sensor proteins STIM1 and STIM2 are crucial elements of store-operated calcium entry (SOCE) in breast cancer cells. Increased SOCE activity may contribute to epithelial-mesenchymal transitions (EMT) and increase cell migration and invasion. However, the roles of STIM1 and STIM2 in TGF-β-induced EMT are still unclear. In this study, we demonstrate roles of STIMs in TGF-β-induced EMT in breast cancer cells. In particular, STIM1 and STIM2 expression affected TGF-β-induced EMT by mediating SOCE in MDA-MB-231 and MCF-7 breast cancer cells. The specific SOCE inhibitor YM58483 blocked TGF-β-induced EMT, and differing effects of STIM1 and STIM2 on TGF-β-induced EMT correlated with differing roles in SOCE. Finally, we showed that STIM2 is associated with non-store-operated calcium entry (non-SOCE) during TGF-β-induced EMT, whereas STIM1 is not. What's more, non-SOCE have a large possibility to be ROCE. In conclusion, STIM1 and STIM2 proteins play important roles in TGF-β-induced EMT and these effects are related to both SOCE and non-SOCE.

Mathematical model of TGF-βsignalling: feedback coupling is consistent with signal switching

Background

Transforming growth factor β (TGF-β) signalling regulates the development of embryos and tissue homeostasis in adults. In conjunction with other oncogenic changes, long-term perturbation of TGF-β signalling is associated with cancer metastasis. Although TGF-β signalling can be complex, many of the signalling components are well defined, so it is possible to develop mathematical models of TGF-β signalling using reduction and scaling methods. The parameterization of our TGF-β signalling model is consistent with experimental data.

Results

We developed our mathematical model for the TGF-β signalling pathway, i.e. the RF- model of TGF-β signalling, using the “rapid equilibrium assumption” to reduce the network of TGF-β signalling reactions based on the time scales of the individual reactions. By adding time-delayed positive feedback to the inherent time-delayed negative feedback for TGF-β signalling. We were able to simulate the sigmoidal, switch-like behaviour observed for the concentration dependence of long-term (> 3 hours) TGF-β stimulation. Computer simulations revealed the vital role of the coupling of the positive and negative feedback loops on the regulation of the TGF-β signalling system. The incorporation of time-delays for the negative feedback loop improved the accuracy, stability and robustness of the model. This model reproduces both the short-term and long-term switching responses for the intracellular signalling pathways at different TGF-β concentrations. We have tested the model against experimental data from MEF (mouse embryonic fibroblasts) WT, SV40-immortalized MEFs and Gp130 ^F/F MEFs. The predictions from the RF- model are consistent with the experimental data.

Conclusions

Signalling feedback loops are required to model TGF-β signal transduction and its effects on normal and cancer cells. We focus on the effects of time-delayed feedback loops and their coupling to ligand stimulation in this system. The model was simplified and reduced to its key components using standard methods and the rapid equilibrium assumption. We detected differences in short-term and long-term signal switching. The results from the RF- model compare well with experimental data and predict the dynamics of TGF-β signalling in cancer cells with different mutations.

Electronic supplementary material

The online version of this article (doi:10.1186/s12918-017-0421-5) contains supplementary material, which is available to authorized users.

TGF-β1 induces HMGA1 expression: The role of HMGA1 in thyroid cancer proliferation and invasion

The role of transforming growth factor-β1 (TGF-β1) is complicated and plays a different role in the development of cancer. High mobility group A (HMGA1) participates in multiple cellular biology processes, and exerts important roles in the epithelial-mesenchymal transition (EMT). However, the correlation of TGF-β1 and HMGA1 in cancer cells is not yet fully understood. In this study, we determined the effects of TGF-β1 on HMGA1 expression in thyroid cancer cells and examined the role of HMGA1 in thyroid cancer progression. With real-time PCR and immunofluorescence staining, our study demonstrated that TGF-β1 induced the expression of HMGA1 through phosphoinositide 3-kinase (PI3K) and the extracellular signal-related kinase (ERK) signaling in thyroid cancer cells. With luciferase reported assay, the HMGA1 promoter activity was activated by TGF-β1 in the SW579 cells. Furthermore, lentivirus-mediated HMGA1 knockdown inhibits cellular oncogenic properties of thyroid cancer cells. Clinically, tissue microarray revealed that HMGA1 was expressed in thyroid carcinoma more than that in normal thyroid tissues (P<0.001); expression of HMGA1 and MMP-2 was identified to be positively correlated (P=0.017). The present study established the first link between HMGA1 and TGF-β1 in the regulation of thyroid cancer proliferation and invasion, and provided evidence for the pivotal role of HMGA1 in the progression of thyroid cancer, indicating HMGA1 to be potential biological marker for the diagnosis of thyroid cancer.

CCT6A suppresses SMAD2 and promotes prometastatic TGF-β signaling

Paradoxically, during early tumor development in many cancer types, TGF-β acts as a tumor suppressor, whereas in the advanced stages of these cancers, increased TGF-β expression is linked to high metastasis and poor prognosis. These findings suggest that unidentified mechanisms may function to rewire TGF-β signaling toward its prometastatic role in cancer cells. Our current study using non-small-cell lung carcinoma (NSCLC) cell lines, animal models, and clinical specimens demonstrates that suppression of SMAD2, with SMAD3 function intact, switches TGF-β-induced transcriptional responses to a prometastatic state. Importantly, we identified chaperonin containing TCP1 subunit 6A (CCT6A) as an inhibitor and direct binding protein of SMAD2 and found that CCT6A suppresses SMAD2 function in NSCLC cells and promotes metastasis. Furthermore, selective inhibition of SMAD3 or CCT6A efficiently suppresses TGF-β-mediated metastasis. Our findings provide a mechanism that directs TGF-β signaling toward its prometastatic arm and may contribute to the development of therapeutic strategies targeting TGF-β for NSCLC.

Overexpression of SASH1 Inhibits TGF-β1-Induced EMT in Gastric Cancer Cells

The epithelial–mesenchymal transition (EMT) is considered to be one of the critical steps in gastric cancer cell invasion and metastasis. SAM- and SH3-domain containing 1 (SASH1), a member of the SLY family of signal adapter proteins, is a candidate for tumor suppression in several cancers. However, the biological role of SASH1 in gastric cancer remains largely unknown. Therefore, the purpose of this study was to investigate the impact of SASH1 on the biological behavior of gastric cancer cells treated with transforming growth factor (TGF)-β1. In the current study, we provide evidence that SASH1 was lowly expressed in human gastric cancer cells, and TGF-β1 also inhibited the expression of SASH1 in TSGH cells. We found that SASH1 inhibited TGF-β1-mediated EMT in TSGH cells, as well as cell migration and invasion. Furthermore, SASH1 obviously inhibited the phosphorylation of PI3K and Akt in TGF-β1-stimulated TSGH cells. In summary, our study is the first to show that overexpression of SASH1 inhibits TGF-β1-induced EMT in gastric cancer cells through the PI3K/Akt signaling pathway. These results suggest that SASH1 may be a potential therapeutic target for the treatment of gastric cancer.

In situ localization of tumor cells associated with the epithelial-mesenchymal transition marker Snail and the prognostic impact of lymphocytes in the tumor microenvironment in invasive ductal breast cancer

PURPOSE

Tumor surgery is aimed at complete resection of the lesion while ensuring a sufficient tumor-specific safety distance. Nevertheless, in many cases the most peripheral part - the invasion front - remains in situ. Tumor cells at the tumor margin have been reported to lose their epithelial properties and acquire features of mesenchymal cells. The process of epithelial-to-mesenchymal transition (EMT) is believed to be of prime importance for tissue and vessel invasion. Furthermore, the detection of tumor-infiltrating lymphocytes in the microenvironment of breast cancer might serve as a reliable prognostic marker.

METHODS

We investigated tissue microarrays of 352 breast cancer patients with regard to the presence and distribution of the EMT factor Snail, and the presence of FoxP3, CD3 and CD8 in the immune microenvironment.

RESULTS

The expression of the transcription factor Snail is strongly associated with longer disease-free and overall survival. The presence of CD3, CD8 or FoxP3 is associated with a better outcome, although statistically significant results were noted only for FoxP3. The prognostic significance of FoxP3 and Snail were also proven in multivariate analysis.

CONCLUSIONS

Based on previous studies concerning the intratumoral heterogeneity of EMT, our results suggest that Snail and FoxP3 are possible prognostic markers for breast cancer. The diverse presence of lymphocytes in the tumor microenvironment (CD3 and CD8) was confirmed. Although the importance of these markers is known, their specific role in tumor invasion and metastasis as well as their hierarchical organization in these tumors remain unclear.

Lysophosphatidic Acid Promotes Epithelial to Mesenchymal Transition in Ovarian Cancer Cells by Repressing SIRT1

BACKGROUND/AIMS

Epithelial-to-mesenchymal transition (EMT) plays an essential role in the transition from early to invasive phenotype, however the underlying mechanisms still remain elusive. Herein, we propose a mechanism through which the class-III deacetylase SIRT1 regulates EMT in ovarian cancer (OC) cells.

METHODS

Expression analysis was performed using Q-PCR, western blot, immunofluorescence and fluorescence-IHC study. Matrigel invasion assay was used for the invasion study. Morphological alterations were observed by phalloidin-staining. Co-immunoprecipitation study was performed to analyze protein-protein interaction.

RESULTS

Overexpression of SIRT1-WT as well as Resveratrol-mediated SIRT1 activation antagonized the invasion of OC cells by suppressing EMT. SIRT1 deacetylates HIF1α, to inactivate its transcriptional activity. To further validate HIF1α inactivation, its target gene, i.e. ZEB1, an EMT-inducing factor was found to attenuate upon SIRT1 activation. To uncover the regulatory factor governing SIRT1 expression, lysophosphatidic acid (LPA), a highly enriched oncolipid in ascites/serum of OC patients, was found to down-regulate SIRT1 expression. Importantly, LPA was found to induce the mesenchymal switch in OC cells through suppression of SIRT1. Decreased level of SIRT1 was further validated in ovarian tissue samples of OC patients.

CONCLUSION

We have identified a mechanism that relates SIRT1 down-regulation to LPA-induced EMT in OC cells and may open new arenas on developing novel anti-cancer therapeutics.

Regulation of EMT by STAT3 in gastrointestinal cancer (Review)

Gastrointestinal (GI) cancer is characterized by its aggressiveness and tendency to metastasize at early stage. Epithelial-mesenchymal transition (EMT), commonly known as the preparing step of metastasis, may account for the aggressive phenotype of GI cancer cells. The process of EMT is finely orchestrated by multiple layers of regulators. Signal transducer and activator of transcription 3 (STAT3) is a transcription factor constitutively activated in diverse malignancies. Recent studies have suggested an involvement of STAT3 in GI cancer EMT. In this review, we first take an insight into the oncogenic functions of STAT3 in GI cancer, and then summarize the possible mechanisms by which STAT3 regulates the EMT process. Through the extensive interactions with EMT-inducing transcription factors and non-coding RNAs, and crosstalk with other signaling pathways, STAT3 has been demonstrated to promote the mesenchymal and invasive phenotype of GI cancer, which provides rationales for specifically targeting STAT3 to prevent and reverse the progression of GI cancer.