Atrial natriuretic peptide: A novel mediator for TGF-β1-induced epithelial-mesenchymal transition in 16HBE-14o and A549 cells.

Atrial natriuretic peptide (ANP) is increasingly expressed on airway and inhibits pulmonary arterial remodeling. However, the role of ANP in remodeling of respiratory system is still unclear. The role of ANP on airway remodeling and the possible mechanism was explored in this study. Both human bronchial epithelial 16HBE-14o cells and alveolar epithelial A549 cells were stimulated by TGF-β1, ANP, cGMP inhibitor, PKG inhibitor, and cGMP analogue. The expressions of epithelial markers, mesenchymal markers, and Smad3 were assessed by quantitative real-time PCR and western blotting. Immunohistochemical staining was employed to assess Smad3 expression once it was silenced by siRNA in 16HBE-14o or A549 cells. Our results showed that the mRNA and protein expressions of E-Cadherin were decreased, whereas α-SMA expressions were increased after induction by TGF-β1 in 16HBE-14o and A549 cells. The E-Cadherin expressions were increased and α-SMA expressions were decreased after ANP stimulation. Inhibition of cGMP or PKG decreased E-Cadherin expression but increased α-SMA expression, which could be reversed by cGMP analogue. Moreover, the phosphorylated Smad3 expression was consistent with α-SMA expression. After smad3 was silenced, Smad3 was mostly expressed in cytoplasm instead of nucleus as non-silenced cells during epithelial-mesenchymal transition (EMT). In conclusion, ANP inhibits TGF-β1-induced EMT in 16HBE-14o and A549 cells through cGMP/PKG signaling, by which it targets TGF-β1/Smad3 via attenuating phosphorylation of Smad3. These findings suggest the potential of ANP in the treatment on pulmonary diseases with airway remodeling.

Chu S ，Zhang X ，Sun Y ，Yu Y ，Liang Y ，Jiang M ，Huang J ，Ma L ... -  《-》

Atrial natriuretic peptide inhibits epithelial-mesenchymal transition (EMT) of bronchial epithelial cells through cGMP/PKG signaling by targeting Smad3 in a murine model of allergic asthma.

Chu S ，Zhang X ，Sun Y ，Liang Y ，Sun J ，Lu M ，Huang J ，Jiang M ，Ma L ... -  《-》

Therapeutic effects of conditioned medium from bone marrow-derived mesenchymal stem cells on epithelial-mesenchymal transition in A549 cells.

Wang X ，Gao JL ，Zhao MM ，Zhu HX ，Tian YX ，Li R ，Jiang XH ，Yu L ，Tian JR ，Cui JZ ... -  《-》

Simvastatin attenuates TGF-β1-induced epithelial-mesenchymal transition in human alveolar epithelial cells.

Transforming growth factor-β1 (TGF-β1)-induced epithelial-mesenchymal transition (EMT) of alveolar epithelial cells (AEC) may contribute to idiopathic pulmonary fibrosis (IPF). TGF-β1-induced EMT in A549 cells (a human AEC cell line) resulted in the adoption of mesenchymal responses that were predominantly mediated via the TGF-β1-Smad2/3 signaling pathway. Simvastatin (Sim), a 3-hydroxy-3-methylglutaryl CoA (HMG-CoA) reductase inhibitor, has been previously reported to inhibit EMT in human proximal tubular epithelial cells and porcine lens epithelial cells and to suppress Smad2/3 phosphorylation in animal models. However, whether Sim can attenuate TGF-β1-induced EMT in A549 cells and its underlying mechanisms remains unknown. Cells were incubated with TGF-β1 in the presence or absence of Sim. The epithelial marker E-cadherin (E-Cad) and the mesenchymal markers, α-smooth muscle actin (α-SMA), vimentin (Vi) and fibronectin (FN), were detected using western blotting analyses and immunofluorescence. Phosphorylated Smad2 and Smad3 levels and connective tissue growth factor (CTGF) were analyzed using western blotting. In addition, a cell migration assay was performed. Moreover, the levels of matrix metalloproteinase (MMP)-2 and -9 in the culture medium were examined using ELISA. Sim significantly attenuated the TGF-β1-induced decrease in E-Cad levels and elevated the levels of α-SMA, Vi and FN via the suppression of Smad2 and Smad3 phosphorylation. Furthermore, Sim inhibited the mesenchymal-like responses in A549 cells, including cell migration, CTGF expression and secretion of MMP-2 and -9. However, Sim failed to reverse the cell morphologial changes induced by TGF-β1 in A549 cells. Sim attenuated TGF-β1-induced EMT in A549 cells and might be a promising therapeutic agent for treating IPF.

Yang T ，Chen M ，Sun T 《-》

LPS-induced epithelial-mesenchymal transition of intrahepatic biliary epithelial cells.

Recent studies have revealed that the epithelial-mesenchymal transition (EMT) of bile duct epithelial cells is engaged in hepatic fibrogenesis. However, the association between etiological factors of liver disease such as virus or bacterial infection and EMT remains to be investigated. The present study focuses on the inductive role of endotoxin, the main component of the cell wall's ectoblast of gram-negative bacteria, in the EMT of human intrahepatic biliary epithelial cells (HIBEpiCs). The expressions of E-cadherin, S100A4, α-SMA, TGF-β1, and Smad2/3 in HIBEpiCs cultured with or without lipopolysaccharide LPS, were detected by real-time PCR and Western blotting. We blocked the expression of TGF-β1 using paclitaxel and knocked down Smad2/3 by siRNA to explore the role of TGF-β1/Smad2/3 pathway in the EMT of HIBEpiCs. Resting HIBEpiCs showed epithelioid cobblestone morphology, and underwent a phenotypic change to produce bipolar cells with a fibroblastic morphology when co-cultured with LPS. After LPS stimulation and the up-regulation of mRNA and protein expression of TGF-β1 and Smad2/Smad3, the mRNA and protein expression of mesenchymal markers (S100A and α-SMA) increased significantly. Paclitaxel inhibited the mRNA and protein expression of TGF-β1 in vitro. Knock-down of Smad2/3 by siRNA led to up-regulation of epithelial markers E-cadherin and down-regulation of S100A and α-SMA, indicating a reversal of the EMT. LPS can induce the expression of TGF-ß1 and a subsequent EMT in HIBEpiCs, and the inhibition of TGF-ß1 or Smad 2/3 could reverse this EMT, suggesting that LPS may play a potential role in the EMT of HIBEpiCs.

Zhao L ，Yang R ，Cheng L ，Wang M ，Jiang Y ，Wang S ... -  《-》