Abstract
Transforming growth factor beta (TGFbeta) contributes to tumor progression by inducing an epithelial to mesenchymal transdifferentiation (EMT) and cell migration. We found that TGFbeta-induced EMT was blocked by inhibiting activation of p38 mitogen-activated protein kinase (MAPK) with H-7, a protein kinase C inhibitor, and with SB202190, a direct inhibitor of p38MAPK. Inhibition of the p38MAPK pathway affected TGFbeta-mediated phosphorylation of ATF2, but did not inhibit phosphorylation of Smad2. SB202190 impaired TGFbeta-mediated changes in cell shape and reorganization of the actin cytoskeleton. Forced expression of dominant-negative (DN) MAPK kinase 3 (MKK3) inhibited TGFbeta-mediated activation of p38MAPK and EMT. Expression of DN-p38alpha impaired TGFbeta-induced EMT. Inhibition of p38MAPK blocked TGFbeta-induced migration of non-tumor and tumor mammary epithelial cells. TGFbeta induced activation of the p38MAPK pathway within 15 minutes. Expression of TGFbeta type II (TbetaRII) and type I (TbetaRI/Alk5) kinase-inactive receptors blocked EMT and activation of p38MAPK, whereas expression of constitutively active Alk5-T204D resulted in EMT and phosphorylation of MKK3/6 and p38MAPK. Finally, dominant-negative Rac1N17 blocked TGFbeta-induced activation of the p38MAPK pathway and EMT, suggesting that Rac1 mediates activation of the p38MAPK pathway. These studies suggest that the p38MAPK pathway is required for TGFbeta-mediated EMT and cell migration.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Actin Cytoskeleton / drug effects
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Actin Cytoskeleton / metabolism
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Activating Transcription Factor 2
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Animals
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Cell Differentiation / drug effects
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Cell Differentiation / physiology*
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Cell Movement / drug effects
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Cell Movement / physiology*
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Cell Size / drug effects
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Cell Size / genetics
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Cell Transformation, Neoplastic / drug effects
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Cell Transformation, Neoplastic / genetics
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Cell Transformation, Neoplastic / metabolism*
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Cyclic AMP Response Element-Binding Protein / drug effects
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Cyclic AMP Response Element-Binding Protein / metabolism
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DNA-Binding Proteins / drug effects
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DNA-Binding Proteins / metabolism
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Enzyme Inhibitors / pharmacology
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Epithelial Cells / cytology
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Epithelial Cells / drug effects
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Epithelial Cells / metabolism*
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Fibroblasts / drug effects
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Fibroblasts / metabolism
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Humans
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Mesoderm / cytology
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Mesoderm / drug effects
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Mesoderm / metabolism*
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Mice
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Mitogen-Activated Protein Kinases / antagonists & inhibitors
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Mitogen-Activated Protein Kinases / drug effects
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Mitogen-Activated Protein Kinases / metabolism*
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Mutation / genetics
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Plant Proteins*
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Receptors, Transforming Growth Factor beta / genetics
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Receptors, Transforming Growth Factor beta / metabolism
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Smad Proteins
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Trans-Activators / drug effects
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Trans-Activators / metabolism
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Transcription Factors / drug effects
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Transcription Factors / metabolism
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Transforming Growth Factor beta / metabolism*
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Transforming Growth Factor beta / pharmacology
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Tumor Cells, Cultured
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p38 Mitogen-Activated Protein Kinases
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rac1 GTP-Binding Protein / genetics
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rac1 GTP-Binding Protein / metabolism
Substances
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ATF2 protein, human
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Activating Transcription Factor 2
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Atf2 protein, mouse
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Cyclic AMP Response Element-Binding Protein
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DNA-Binding Proteins
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Enzyme Inhibitors
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Plant Proteins
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Receptors, Transforming Growth Factor beta
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Smad Proteins
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Trans-Activators
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Transcription Factors
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Transforming Growth Factor beta
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Mitogen-Activated Protein Kinases
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p38 Mitogen-Activated Protein Kinases
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rac1 GTP-Binding Protein