Expression and activity of phosphodiesterase isoforms during epithelial mesenchymal transition: the role of phosphodiesterase 4.
Epithelial-mesenchymal transition (EMT) has emerged as a critical event in the pathogenesis of organ fibrosis and cancer and is typically induced by the multifunctional cytokine transforming growth factor (TGF)-beta1. The present study was undertaken to evaluate the potential role of phosphodiesterases (PDEs) in TGF-beta1-induced EMT in the human alveolar epithelial type II cell line A549. Stimulation of A549 with TGF-beta1 induced EMT by morphological alterations and by expression changes of the epithelial phenotype markers E-cadherin, cytokeratin-18, zona occludens-1, and the mesenchymal phenotype markers, collagen I, fibronectin, and alpha-smooth muscle actin. Interestingly, TGF-beta1 stimulation caused twofold increase in total cAMP-PDE activity, contributed mostly by PDE4. Furthermore, mRNA and protein expression demonstrated up-regulation of PDE4A and PDE4D isoforms in TGF-beta1-stimulated cells. Most importantly, treatment of TGF-beta1 stimulated epithelial cells with the PDE4-selective inhibitor rolipram or PDE4 small interfering RNA potently inhibited EMT changes in a Smad-independent manner by decreasing reactive oxygen species, p38, and extracellular signal-regulated kinase phosphorylation. In contrast, the ectopic overexpression of PDE4A and/or PDE4D resulted in a significant loss of epithelial marker E-cadherin but did not result in changes of mesenchymal markers. In addition, Rho kinase signaling activated by TGF-beta1 during EMT demonstrated to be a positive regulator of PDE4. Collectively, the findings presented herein suggest that TGF-beta1 mediated up-regulation of PDE4 promotes EMT in alveolar epithelial cells. Thus, targeting PDE4 isoforms may be a novel approach to attenuate EMT-associated lung diseases such as pulmonary fibrosis and lung cancer.
Kolosionek
Ewa
E
University of Giessen Lung Centre, Giessen, Germany.
Savai
Rajkumar
R
Ghofrani
Hossein Ardeschir
HA
Weissmann
Norbert
N
Guenther
Andreas
A
Grimminger
Friedrich
F
Seeger
Werner
W
Banat
Gamal Andre
GA
Schermuly
Ralph Theo
RT
Pullamsetti
Soni Savai
SS
D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002460:Cell Line; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4 / Q000235:genetics / Q000378:metabolism*; D004847:Epithelial Cells / Q000166:cytology / Q000502:physiology; D004848:Epithelium / Q000502:physiology*; D055785:Gene Knockdown Techniques; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D008648:Mesoderm / Q000502:physiology*; D008969:Molecular Sequence Data; D058988:Phosphodiesterase 4 Inhibitors; D010726:Phosphodiesterase Inhibitors / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000166:cytology / Q000502:physiology; D034622:RNA Interference; D017382:Reactive Oxygen Species / Q000378:metabolism; D020889:Rolipram / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology; D051785:Smad Proteins / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D054460:rho-Associated Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism
D015415:Biomarkers; D007527:Isoenzymes; D058988:Phosphodiesterase 4 Inhibitors; D010726:Phosphodiesterase Inhibitors; D017382:Reactive Oxygen Species; D051785:Smad Proteins; D053773:Transforming Growth Factor beta1; D054460:rho-Associated Kinases; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D020742:rhoA GTP-Binding Protein; D020889:Rolipram