Basic fibroblast growth factor in the bone microenvironment enhances cell motility and invasion of Ewing's sarcoma family of tumours by activating the FGFR1-PI3K-Rac1 pathway.
BACKGROUND
Ewing's sarcoma family of tumours (ESFT) is a malignant small round-cell tumour of the bone and soft tissues. It is characterised by a strong tendency to invade and form metastases. The microenvironment of the bone marrow is a large repository for many growth factors, including the basic fibroblast growth factor (bFGF). However, the role of bFGF in the invasive and metastatic phenotype of ESFT has not been investigated.


METHODS
The motility and invasion of ESFT cells were assessed by a wound-healing assay, chemotaxis assay, and invasion assay. The expression and activation of FGF receptors (FGFRs) in ESFT cell lines and clinical samples were detected by RT-PCR, western blotting, and immunohistochemistry. The morphology of ESFT cells was investigated by phase-contrast microscopy and fluorescence staining for actin. Activation of Rac1 was analysed by a pull-down assay.


RESULTS
bFGF strongly induced the motility and invasion of ESFT cells. Furthermore, FGFR1 was found to be expressed and activated in clinical samples of ESFT. Basic FGF-induced cell motility was mediated through the FGFR1-phosphatidylinositol 3-kinase (PI3K)-Rac1 pathway. Conditioned medium from bone marrow stromal cells induced the motility of ESFT cells by activating bFGF/FGFR1 signalling.


CONCLUSIONS
The bFGF-FGFR1-PI3K-Rac1 pathway in the bone microenvironment may have a significant role in the invasion and metastasis of ESFT.
Kamura
S
S
Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan.
Matsumoto
Y
Y
Fukushi
J-I
JI
Fujiwara
T
T
Iida
K
K
Okada
Y
Y
Iwamoto
Y
Y
D001853:Bone Marrow / Q000502:physiology* / Q000503:physiopathology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D003599:Cytoskeleton / Q000473:pathology; D004789:Enzyme Activation; D004815:Epidermal Growth Factor / Q000494:pharmacology; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D006801:Humans; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D012516:Osteosarcoma / Q000235:genetics / Q000473:pathology; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics* / Q000378:metabolism; D016133:Polymerase Chain Reaction; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000235:genetics* / Q000378:metabolism; D051498:Receptor, Fibroblast Growth Factor, Type 3 / Q000235:genetics; D011994:Recombinant Proteins / Q000494:pharmacology; D012512:Sarcoma, Ewing / Q000235:genetics* / Q000473:pathology*; D014945:Wound Healing; D020830:rac1 GTP-Binding Protein / Q000235:genetics* / Q000378:metabolism
D011994:Recombinant Proteins; D016222:Fibroblast Growth Factor 2; D004815:Epidermal Growth Factor; D019869:Phosphatidylinositol 3-Kinases; C496365:FGFR3 protein, human; D051496:Receptor, Fibroblast Growth Factor, Type 1; D051498:Receptor, Fibroblast Growth Factor, Type 3; D020830:rac1 GTP-Binding Protein