title: EphA4 promotes cell proliferation and migration through a novel EphA4-FGFR1 signaling pathway in the human glioma U251 cell line.
abstract: The Eph receptor tyrosine kinases and their ephrin ligands form a unique cell-cell contact-mediated bidirectional signaling mechanism for regulating cell localization and organization. High expression of Eph receptors in a wide variety of human tumors indicates some roles in tumor progression, which makes these proteins potential targets for anticancer therapy. For this purpose, we did gene expression profiling for 47 surgical specimens of brain tumors including 32 high-grade glioma using a microarray technique. The analysis, focused on the receptor tyrosine kinases, showed that EphA4 mRNA in the tumors was 4-fold higher than in normal brain tissue. To investigate the biological significance of EphA4 overexpression in these tumors, we analyzed EphA4-induced phenotypic changes and the signaling mechanisms using human glioma U251 cells. EphA4 promoted fibroblast growth factor 2-mediated cell proliferation and migration accompanied with enhancement of fibroblast growth factor 2-triggered mitogen-activated protein kinase and Akt phosphorylation. In addition, active forms of Rac1 and Cdc42 increased in the EphA4-overexpressing cells. Furthermore, we found that EphA4 formed a heteroreceptor complex with fibroblast growth factor receptor 1 (FGFR1) in the cells and that the EphA4-FGFR1 complex potentiated FGFR-mediated downstream signaling. Thus, our results indicate that EphA4 plays an important role in malignant phenotypes of glioblastoma by enhancing cell proliferation and migration through accelerating a canonical FGFR signaling pathway.
authors.affiliation: Department of Neurological Surgery, Wakayama Medical University, Wakayama, Japan.
authors.forename: Junya
authors.initials: J
authors.lastname: Fukai
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Yokote
authors.forename: Ryuya
authors.initials: R
authors.lastname: Yamanaka
authors.forename: Tokuzo
authors.initials: T
authors.lastname: Arao
authors.forename: Kazuto
authors.initials: K
authors.lastname: Nishio
authors.forename: Toru
authors.initials: T
authors.lastname: Itakura
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D005910:Glioma / Q000201:enzymology / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D036122:Receptor, EphA4 / Q000235:genetics / Q000378:metabolism*; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C106534:FRS2 protein, human; D008565:Membrane Proteins; D012333:RNA, Messenger; D016222:Fibroblast Growth Factor 2; D036122:Receptor, EphA4; D051496:Receptor, Fibroblast Growth Factor, Type 1; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases; D020764:cdc42 GTP-Binding Protein; D020830:rac1 GTP-Binding Protein