title: Phosphoinositide-3 kinase-Rac1-c-Jun NH2-terminal kinase signaling mediates collagen I-induced cell scattering and up-regulation of N-cadherin expression in mouse mammary epithelial cells.
abstract: During epithelial-to-mesenchymal transitions (EMTs), cells must change their interactions with one another and with their extracellular matrix in a synchronized manner. To characterize signaling pathways cells use to coordinate these changes, we used NMuMG mammary epithelial cells. We showed that these cells become fibroblastic and scattered, with increased N-cadherin expression when cultured on collagen I. Rac1 and c-Jun NH2-terminal kinase (JNK) were activated when cells were plated on collagen I, and dominant inhibitory Rac1 (RacN17) or inhibition of JNK signaling prevented collagen I-induced morphological changes and N-cadherin up-regulation. Furthermore, inhibiting phosphoinositide-3 kinase (PI3K) activity prevented Rac1 and JNK activation as well as collagen I-induced N-cadherin up-regulation. These data implicate PI3K-Rac1-JNK signaling in collagen I-induced changes in NMuMG cells. To establish a role for N-cadherin in collagen I-induced cell scattering, we generated N-cadherin overexpressing and knockdown NMuMG cells and showed that knocking down N-cadherin expression prevented collagen I-induced morphological changes. Motility assays showed that cells overexpressing N-cadherin were significantly more motile than mock-transfected cells and that N-cadherin-mediated motility was collagen I dependent. In addition, we showed that cord formation and branching in three-dimensional culture (EMT-dependent events) required N-cadherin expression and PI3K-Rac1-JNK signaling.
authors.affiliation: Department of Oral Biology, Eppley Institute for Research in Cancer and Allied Diseases, and Eppley Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198-7696, USA.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Shintani
authors.forename: Margaret J
authors.initials: MJ
authors.lastname: Wheelock
authors.forename: Keith R
authors.initials: KR
authors.lastname: Johnson
mesh_terms: D000818:Animals; D015820:Cadherins / Q000235:genetics / Q000378:metabolism*; D018929:Cell Culture Techniques; D002454:Cell Differentiation; D002465:Cell Movement; D002478:Cells, Cultured; D024042:Collagen Type I / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D016023:Integrins / Q000378:metabolism; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism*; D008321:Mammary Glands, Animal / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D008648:Mesoderm; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D015398:Signal Transduction; D015854:Up-Regulation; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*
chemical_list: D015820:Cadherins; D024042:Collagen Type I; D016023:Integrins; D019869:Phosphatidylinositol 3-Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020830:rac1 GTP-Binding Protein