title: Tyrosine phosphorylation of paxillin affects the metastatic potential of human osteosarcoma.
abstract: To acquire information on signal alteration corresponding to the changes in metastatic potential, we analysed protein tyrosine phosphorylation of low- and high-metastatic human osteosarcoma HuO9 sublines, which were recently established as the first metastatic model of human osteosarcoma. Tyrosine phosphorylation of proteins around 60, 70, and 120-130 kDa was enhanced in high-metastatic sublines. Among these proteins, the protein around 70 kDa, which was most remarkably phosphorylated, was identified as paxillin, a scaffold protein in integrin signaling. Activity of Src family kinase correlated well with metastatic potential, and a Src family kinase inhibitor, PP2, not only abolished tyrosine phosphorylation of paxillin but also impaired the motility of high-metastatic sublines. The expression of paxillin was also elevated in high-metastatic sublines, and knocking down of paxillin expression by RNAi method resulted in attenuated motility of high-metastatic cells. We also demonstrated that the phosphorylated form of paxillin is essential for the migration-promoting effect in human osteosarcoma. These findings suggest that enhanced activity of Src family kinases and overexpression of paxillin synergistically contribute to the high metastatic potential of human osteosarcoma through the hyperphosphorylation of paxillin.
authors.affiliation: Growth Factor Division, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Azuma
authors.forename: Masamitsu
authors.initials: M
authors.lastname: Tanaka
authors.forename: Takamasa
authors.initials: T
authors.lastname: Uekita
authors.forename: Satoshi
authors.initials: S
authors.lastname: Inoue
authors.forename: Jun
authors.initials: J
authors.lastname: Yokota
authors.forename: Yasuyoshi
authors.initials: Y
authors.lastname: Ouchi
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Sakai
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002465:Cell Movement; D003598:Cytoskeletal Proteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D009362:Neoplasm Metastasis / Q000235:genetics / Q000473:pathology; D012516:Osteosarcoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D051419:Paxillin; D010750:Phosphoproteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D034622:RNA Interference; D050717:Retinoblastoma-Like Protein p130; D019061:src-Family Kinases / Q000378:metabolism
chemical_list: D003598:Cytoskeletal Proteins; C496061:PXN protein, human; D051419:Paxillin; D010750:Phosphoproteins; D011506:Proteins; D050717:Retinoblastoma-Like Protein p130; D019000:Phosphotyrosine; D019061:src-Family Kinases