title: Focal adhesion kinase is activated in invading fibrosarcoma cells and regulates metastasis.
abstract: Focal adhesion kinase (FAK) is a nonreceptor tyrosine kinase that is overexpressed in several human cancers, and induces survival, proliferation and motility of cells in culture. Phosphorylation of FAK has been studied extensively in vitro, but little is known about its regulation during tumor invasion in vivo. In the current study, green fluorescent protein (GFP) was expressed stably in an invasive murine fibrosarcoma cell line for the purpose of discrimination between tumor and normal cells. Under fluorescence microscopy, the tumor was highly fluorescent, and the margin between the tumor and normal tissue was clearly demarcated. Using this invasion model, we showed localization of pY397-FAK expression in the infiltrative edge of tumors. We reproduced local invasion in vivo using a tumor tissue culture method in a three dimensional collagen gel. Phosphorylation of FAK is also upregulated in invading fibrosarcoma cells under in vitro conditions. Expression of the FAK C-terminal domain termed FRNK (FAK-related non-kinase) in 2,472 cells decreased FAK phosphorylation without changing total FAK levels. FRNK inhibited the motility of 2,472 cells, and reduced invasion in vitro. Although FRNK did not affect cell growth, it inhibited experimental metastases in syngenic mice. These results demonstrate that the phosphorylation of FAK might be specifically upregulated in invading fibrosarcoma cells and regulate their invasion and metastasis.
authors.affiliation: Department of Orthopedic Surgery, Graduate School of Medical Sciences, Kyushu University, Higashi-ku, Fukuoka, Japan.
authors.forename: Masuo
authors.initials: M
authors.lastname: Hanada
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Tanaka
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: Fumihiko
authors.initials: F
authors.lastname: Nakatani
authors.forename: Riku
authors.initials: R
authors.lastname: Sakimura
authors.forename: Tomoya
authors.initials: T
authors.lastname: Matsunobu
authors.forename: Xu
authors.initials: X
authors.lastname: Li
authors.forename: Takamitsu
authors.initials: T
authors.lastname: Okada
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Nakamura
authors.forename: Minoru
authors.initials: M
authors.lastname: Takasaki
authors.forename: Yukihide
authors.initials: Y
authors.lastname: Iwamoto
mesh_terms: D000818:Animals; D045744:Cell Line, Tumor; D002465:Cell Movement; D005354:Fibrosarcoma / Q000201:enzymology* / Q000473:pathology / Q000556:secondary*; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000378:metabolism; D051379:Mice; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D049452:Green Fluorescent Proteins; C113183:FAK-related nonkinase; D011505:Protein-Tyrosine Kinases; D051416:Focal Adhesion Protein-Tyrosine Kinases