title: Mesenchymal mode of migration participates in pulmonary metastasis of mouse osteosarcoma LM8.
abstract: The outcomes of osteosarcoma patients still remain poor because of intractable pulmonary metastasis. We previously established a highly metastatic osteosarcoma cell line, LM8 from Dunn mouse osteosarcoma by in vivo selection. We herein aimed to clarify the characteristic biological features related with high metastatic potential and new target molecules to suppress pulmonary metastasis of osteosarcoma, using this syngeneic spontaneous metastatic model. LM8 cells acquired fibroblastic morphology with striking filopodia on the cell surface. Immunostaining showed faint stress fiber formation and peripherally localized integrin β1, and biochemical analyses showed the activated Cdc42 and autophosphorylation of focal adhesion kinase (FAK) in LM8 cells when compared to Dunn cells. LM8 cells had activated motility in single cell migration mode. LM8 migration was increased by a Rho-associated kinase (ROCK) inhibitor, Y-27632, while decreased by Cdc42 silencing using RNA interference system. We found that a clinically approved camptothecin analog, irinotecan suppressed the migration, Cdc42 activity, and autophosphorylation of FAK, and attenuated integrin β1 distribution selectively in LM8 cells. Daily oral administration of irinotecan significantly reduced the rate and size of pulmonary metastasis in syngeneic C3H mice. The fibroblastic morphology and activated cell migration with the dependency on Cdc42 but not Rho-ROCK signaling pathway argued that LM8 moved in mesenchymal mode of cell migration. This activated mesenchymal migration was a key component of the pulmonary metastasis of LM8 cells. The inhibition of mesenchymal migration by irinotecan, in addition to its cytotoxic effects, might be effective in preventing pulmonary metastasis of osteosarcoma.
authors.affiliation: Department of Pediatrics, Kyoto University Graduate School of Medicine, Shougoin, Sakyo-ku, Japan. yui-yo@mc.pref.osaka.jp
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Yui
authors.forename: Kazuyuki
authors.initials: K
authors.lastname: Itoh
authors.forename: Kiyoko
authors.initials: K
authors.lastname: Yoshioka
authors.forename: Norifumi
authors.initials: N
authors.lastname: Naka
authors.forename: Motonobu
authors.initials: M
authors.lastname: Watanabe
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Hiraumi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Matsubara
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Watanabe
authors.forename: Kazumi
authors.initials: K
authors.lastname: Sano
authors.forename: Tatsutoshi
authors.initials: T
authors.lastname: Nakahata
authors.forename: Souichi
authors.initials: S
authors.lastname: Adachi
mesh_terms: D000818:Animals; D002166:Camptothecin / Q000031:analogs & derivatives / Q000097:blood / Q000494:pharmacology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation; D004195:Disease Models, Animal; D000077146:Irinotecan; D008175:Lung Neoplasms / Q000097:blood / Q000473:pathology* / Q000556:secondary*; D008648:Mesoderm / Q000187:drug effects / Q000473:pathology*; D051379:Mice; D008809:Mice, Inbred C3H; D012516:Osteosarcoma / Q000097:blood / Q000473:pathology*; D015398:Signal Transduction; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism
chemical_list: D000077146:Irinotecan; D020764:cdc42 GTP-Binding Protein; D002166:Camptothecin