title: Cdc42 and the guanine nucleotide exchange factors Ect2 and trio mediate Fn14-induced migration and invasion of glioblastoma cells.
abstract: Malignant glioblastomas are characterized by their ability to infiltrate into normal brain. We previously reported that binding of the multifunctional cytokine TNF-like weak inducer of apoptosis (TWEAK) to its receptor fibroblast growth factor-inducible 14 (Fn14) induces glioblastoma cell invasion via Rac1 activation. Here, we show that Cdc42 plays an essential role in Fn14-mediated activation of Rac1. TWEAK-treated glioma cells display an increased activation of Cdc42, and depletion of Cdc42 using siRNA abolishes TWEAK-induced Rac1 activation and abrogates glioma cell migration and invasion. In contrast, Rac1 depletion does not affect Cdc42 activation by Fn14, showing that Cdc42 mediates TWEAK-stimulated Rac1 activation. Furthermore, we identified two guanine nucleotide exchange factors (GEF), Ect2 and Trio, involved in TWEAK-induced activation of Cdc42 and Rac1, respectively. Depletion of Ect2 abrogates both TWEAK-induced Cdc42 and Rac1 activation, as well as subsequent TWEAK-Fn14-directed glioma cell migration and invasion. In contrast, Trio depletion inhibits TWEAK-induced Rac1 activation but not TWEAK-induced Cdc42 activation. Finally, inappropriate expression of Fn14 or Ect2 in mouse astrocytes in vivo using an RCAS vector system for glial-specific gene transfer in G-tva transgenic mice induces astrocyte migration within the brain, corroborating the in vitro importance of the TWEAK-Fn14 signaling cascade in glioblastoma invasion. Our results suggest that the TWEAK-Fn14 signaling axis stimulates glioma cell migration and invasion through two GEF-GTPase signaling units, Ect2-Cdc42 and Trio-Rac1. Components of the Fn14-Rho GEF-Rho GTPase signaling pathway present innovative drug targets for glioma therapy.
authors.affiliation: Cancer and Cell Biology Division, The Translational Genomics Research Institute, Phoenix, AZ 85004, USA.
authors.forename: Shannon P
authors.initials: SP
authors.lastname: Fortin
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Ennis
authors.forename: Cassie A
authors.initials: CA
authors.lastname: Schumacher
authors.forename: Cassandra R
authors.initials: CR
authors.lastname: Zylstra-Diegel
authors.forename: Bart O
authors.initials: BO
authors.lastname: Williams
authors.forename: Julianna T D
authors.initials: JT
authors.lastname: Ross
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Winkles
authors.forename: Joseph C
authors.initials: JC
authors.lastname: Loftus
authors.forename: Marc H
authors.initials: MH
authors.lastname: Symons
authors.forename: Nhan L
authors.initials: NL
authors.lastname: Tran
mesh_terms: D000818:Animals; D001254:Astrocytoma / Q000235:genetics / Q000378:metabolism; D002465:Cell Movement / Q000235:genetics; D000074049:Cytokine TWEAK; D005909:Glioblastoma / Q000235:genetics / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism; D006801:Humans; D051379:Mice; D009361:Neoplasm Invasiveness / Q000235:genetics; D009479:Neuropeptides / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D000074050:TWEAK Receptor; D048069:Tumor Necrosis Factors / Q000494:pharmacology; D020764:cdc42 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism; D020744:rac GTP-Binding Proteins / Q000378:metabolism; D020830:rac1 GTP-Binding Protein
chemical_list: D000074049:Cytokine TWEAK; C080509:Ect2 protein, mouse; D020662:Guanine Nucleotide Exchange Factors; D009479:Neuropeptides; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; C484602:Rac1 protein, mouse; D018124:Receptors, Tumor Necrosis Factor; C000613297:TNFRSF12A protein, human; C109743:TNFSF12 protein, human; D000074050:TWEAK Receptor; C000613299:Tnfrsf12a protein, mouse; C490975:Trio protein, mouse; D048069:Tumor Necrosis Factors; D017346:Protein Serine-Threonine Kinases; D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein