Negative feedback by SNAI2 regulates TGFβ1-induced amelotin gene transcription in epithelial–mesenchymal transition

Junctional epithelium (JE) demonstrates biological responses with the rapid turnover of gingival epithelial cells. The state occurs in inflammation of gingiva and wound healing after periodontal therapy. To understand the underlying mechanisms and to maintain homeostasis of JE, it is important to investigate roles of JE-specific genes. Amelotin (AMTN) is localized at JE and regulated by inflammatory cytokines and apoptotic factors that represent a critical role of AMTN in stabilizing the dentogingival attachment, which is an entrance of oral bacteria. In this study, we demonstrated that the AMTN gene expression was regulated by SNAI2 and transforming growth factor β1 (TGFβ1)-induced epithelial–mesenchymal transition (EMT) that occurs in wound healing and fibrosis during chronic inflammation. SNAI2 downregulated AMTN gene expression via SNAI2 bindings to E-boxes (E2 and E4) in the mouse AMTN gene promoter in EMT of gingival epithelial cells. Meanwhile, TGFβ1-induced AMTN gene expression was attenuated by SNAI2 and TGFβ1-induced SNAI2, without inhibition of the TGFβ1-Smad3 signaling pathway. Moreover, SNAI2 small interfering RNA (siRNA) rescued SNAI2-induced downregulation of AMTN gene expression, and TGFβ1-induced AMTN gene expression was potentiated by SNAI2 siRNA. Taken together, these data demonstrated that AMTN gene expression in the promotion of EMT was downregulated by SNAI2. The inhibitory effect of AMTN gene expression was an independent feedback on the TGFβ1-Smad3 signaling pathway, suggesting that the mechanism can be engaged in maintaining homeostasis of gingival epithelial cells at JE and the wound healing phase.     

Let-7 Prevents Early Cancer Progression by Suppressing Expression of the Embryonic Gene HMGA2

The microRNA let-7 regulates late embryonic development by suppressing expression of a number of genes such as c-myc and RAS as well as the embryonic gene high mobility group, A2 (HMGA2). We now demonstrate that HMGA2 is more efficiently targeted by let-7 than RAS. Its expression inversely correlates with the expression of let-7 in the NCI60 cells lines, and the expression of RAS does not change when amounts of let-7 that efficiently silence expression of HMGA2 are introduced into tumor cells. We did not find a difference in the expression of HMGA2 between primary ovarian cancer samples and matching metastases, suggesting that the expression of HMGA2 represents an early event during cancer progression. The late repression of HMGA2 by let-7 during embryonic development, and the early reexpression of HMGA2 during cancer development, is in line with the hypothesis that cancer development represents a case of reverse embryogenesis.     

Lysyl oxidase-like 2 is a regulator of angiogenesis through modulation of endothelial-to-mesenchymal transition

Lysyl oxidase-like 2 (LOXL2) belongs to the family of lysyl oxidases, and as such promotes crosslinking of collagens and elastin by oxidative deamination of lysine residues. In endothelial cells (ECs), LOXL2 is involved in crosslinking and scaffolding of collagen IV. Additionally, several reports have shown a role for LOXL2 in other processes, including regulation of gene expression, tumor metastasis, and epithelial-to-mesenchymal transition (EMT). Here, we demonstrate an additional role for LOXL2 in the regulation of angiogenesis by modulation of endothelial-to-mesenchymal transition (EndMT). LOXL2 knockdown in ECs results in decreased migration and sprouting, and concordantly, LOXL2 overexpression leads to an increase in migration and sprouting, independent of its catalytic activity. Furthermore, LOXL2 knockdown resulted in a reduced expression of EndMT markers, and inhibition of transforming growth factor-β (TGF-β)-mediated induction of EndMT. Interestingly, unlike in EMT, overexpression of LOXL2 alone is insufficient to induce EndMT. Further investigation revealed that LOXL2 expression regulates protein kinase B (PKB)/Akt and focal adhesion kinase (FAK) signaling, both pathways that have been implicated in the regulation of EMT. Altogether, our studies reveal a role for LOXL2 in angiogenesis through the modulation of EndMT in ECs, independent of its enzymatic crosslinking activity.     

miR-154 inhibits EMT by targeting HMGA2 in prostate cancer cells

Epithelial–mesenchymal transition (EMT) is a crucial process that plays an important role in the invasion and metastasis of human cancers. High-mobility group AT-hook 2 (HMGA2) has been found to be involved in the EMT program, with its aberrant expression having been observed in a variety of malignant tumors. However, the mechanisms regulating HMGA2 expression remain incompletely understood. The objective of this study was to investigate whether mir-154 plays a critical role in EMT by regulating HMGA2. The expression levels of HMGA2 were examined in four samples of prostate cancer (PCa) tissue and adjacent non-tumorous tissue by Western blot analysis. The effects of forced expression of miR-154 or HMGA2 knockdown on PCa cells were evaluated by cell migration and invasion assays and Western blot analysis. HMGA2 was upregulated in the PCa tissue samples compared with the adjacent normal ones. Forced expression of miR-154 or HMGA2 knockdown significantly reduced the migratory and invasive capabilities of PCa cells in vitro and inhibited EMT gene expression, increased the levels of E-cadherin, an epithelial marker, and decreased the levels of vimentin, a mesenchymal marker. HMGA2 is a direct target gene of miR-154 by dual-luciferase reporter assay. Our findings suggest that miR-154 plays a role in regulating EMT by targeting HMGA2. Understanding the targets and regulating pathways of miR-154 may provide new insights into the underlying pathogenesis of PCa.     

Histone Demethylase KDM6B Promotes Epithelial-Mesenchymal Transition

Epithelial-mesenchymal transition (EMT) is a critical event that occurs in embryonic development, tissue repair control, organ fibrosis, and carcinoma invasion and metastasis. Although significant progress has been made in understanding the molecular regulation of EMT, little is known about how chromatin is modified in EMT. Chromatin modifications through histone acetylation and methylation determine the precise control of gene expression. Recently, histone demethylases were found to play important roles in gene expression through demethylating mono-, di-, or trimethylated lysines. KDM6B (also known as JMJD3) is a histone demethylase that might activate gene expression by removing repressive histone H3 lysine 27 trimethylation marks from chromatin. Here we report that KDM6B played a permissive role in TGF-β-induced EMT in mammary epithelial cells by stimulating SNAI1 expression. KDM6B was induced by TGF-β, and the knockdown of KDM6B inhibited EMT induced by TGF-β. Conversely, overexpression of KDM6B induced the expression of mesenchymal genes and promoted EMT. Chromatin immunoprecipitation (ChIP) assays revealed that KDM6B promoted SNAI1 expression by removing histone H3 lysine trimethylation marks. Consistently, our analysis of the Oncomine database found that KDM6B expression was significantly increased in invasive breast carcinoma compared with normal breast tissues. The knockdown of KDM6B significantly inhibited breast cancer cell invasion. Collectively, our study uncovers a novel epigenetic mechanism regulating EMT and tumor cell invasion, and has important implication in targeting cancer metastasis.     

Tissue reaction to three different types of tissue glues in an experimental aorta dissection model: a quantitative approach

Tissue glues are used during surgical treatment of acute aorta dissection although some glues release toxic products and thus alter the histological structure of the vessel wall. The aim of our study was to use a porcine experimental model of infrarenal aorta dissection to compare histological changes of the vessel wall 1, 6 and 12 months after application of BioGlue, Gelatin-resorcin-formaldehyde (GRF) glue and Tissucol. For quantification, stereological methods were used. All types of glue caused stenosis, GRF most and Tissucol least severely. With increasing postoperative survival time, stenosis was again reduced. Elastine length density decreased with increasing survival time in Control as well as in all Experimental groups. The immunohistochemical phenotype of vascular smooth muscle cells was similar in Tissucol and Control samples. In GRF samples, actin, desmin and vimentin expression changed most severely. Similarly, number and distribution of vasa vasorum in the aortic wall was altered most severely in GRF samples. They tended to return to normal with increasing postoperative survival time, but at a slow rate in the GRF samples. It can be concluded that GRF causes the most severe histopathological changes within the treated aorta, which could be a reason for late failures of dissection surgery. However, glue handling and adhesive properties have to be taken into account, too, when certain glue is chosen for surgical intervention. Increased inflammation and vascularisation might even stabilise the aortic wall. Long-term experimental studies would be helpful to assess healing processes after initial disorganisation of the aortic wall structure.     

FHIT Suppresses Epithelial-Mesenchymal Transition (EMT) and Metastasis in Lung Cancer through Modulation of MicroRNAs

Metastasis is the principal cause of cancer death and occurs through multiple, complex processes that involve the concerted action of many genes. A number of studies have indicated that the Fragile Histidine Triad (FHIT) gene product, FHIT, functions as a tumor suppressor in a variety of common human cancers. Although there are suggestions of a role for FHIT loss in progression of various cancers, a role for such loss in metastasis has not been defined. Here, via in vivo and in vitro assays, we reveal that the enforced expression of FHIT significantly suppresses metastasis, accompanied by inhibition of the epithelial-mesenchymal transition (EMT), a process involved in metastasis through coordinate modulation of EMT-related genes. Specifically, miR-30c, a FHIT-upregulated microRNA, contributes to FHIT function in suppression of EMT and metastasis by directly targeting metastasis genes Metadherin (MTDH), High-mobility group AT—hook 2 (HMGA2), and the mesenchymal markers, Vimentin (VIM) and Fibronectin (FN1), in human lung cancer. Finally, we demonstrate that the expression pattern of FHIT and miR-30c is inversely correlated with that of MTDH and HMGA2 in normal tissue, non-metastatic and metastatic tumors, serving as a potential biomarker for metastasis in lung cancer.     

Early changes in dissected small vessels: experimental study on rat arteries and veins

This study was undertaken to investigate the cause of the early endothelial damage that is seen at sites of microvascular anastomosis and in particular to study the possibility of a connection between damage to the vasa vasorum and subsequent endothelial denudation. Rat femoral vessels were subjected to a variety of experimental injuries, including simple dissection, clamping, and ligation. The vessels were examined in longitudinal section by light microscopy at intervals ranging from 5 minutes to 1 day. The endothelial cells were counted and the numbers were analyzed statistically. In addition, the anatomy of the vasa vasorum was studied using india ink perfusion. Simple dissection of the femoral vessels and excision of the vasa vasorum without interruption of blood flow were followed by ischemic lesions of the tunica media with subendothelial edema and ballooning and exfoliation of endothelial cells. Endothelial denudation reached a maximum level in 30 minutes. Adherence of leukocytes was found on damaged endothelial cells. Mural thrombi were seen in 13.6 percent of arteries and in 40 percent of veins following simple dissection.     

Verbascoside inhibits progression of glioblastoma cells by promoting Let-7g-5p and down-regulating HMGA2 via Wnt/beta-catenin signalling blockade

Glioblastoma (GBM) continues to show a poor prognosis despite advances in diagnostic and therapeutic approaches. The discovery of reliable prognostic indicators may significantly improve treatment outcome of GBM. In this study, we aimed to explore the function of verbascoside (VB) in GBM and its effects on GBM cell biological processes via let-7g-5p and HMGA2. Differentially expressed GBM-related microRNAs (miRNAs) were initially screened. Different concentrations of VB were applied to U87 and U251 GBM cells, and 50 µmol/L of VB was selected for subsequent experiments. Cells were transfected with let-7g-5p inhibitor or mimic, and overexpression of HMGA2 or siRNA against HMGA2 was induced, followed by treatment with VB. The regulatory relationships between VB, let-7g-5p, HMGA2 and Wnt/β-catenin signalling pathway were determined. The results showed that HMGA2 was a direct target gene of let-7g-5p. VB treatment or let-7g-5p overexpression inhibited HMGA2 expression and the activation of Wnt/β-catenin signalling pathway, which further inhibited cell viability, invasion, migration, tumour growth and promoted GBM cell apoptosis and autophagy. On the contrary, HMGA2 overexpression promoted cell viability, invasion, migration, tumour growth while inhibiting GBM cell apoptosis and autophagy. We demonstrated that VB inhibits cell viability and promotes cell autophagy in GBM cells by up-regulating let-7g-5p and down-regulating HMGA2 via Wnt/β-catenin signalling blockade.