We have examined the correlation between matrix metalloproteinase (MMP) expression and metastatic properties of a low metastatic osteosarcoma cell line, osteosarcoma takase (OST), under stimulation by tumour necrosis factor α (TNFα). In vivo, OST cells exhibited significantly increased colonization in the lungs of nude mice in a dose-dependent manner when they were treated by TNFα prior to injection. In vitro, TNFα enhanced tumour cell invasion through the reconstituted basement membrane in a transwell chamber up to 2.5-fold. Gelatin zymography and sandwich enzyme immunoassays demonstrated marked production of MMP-9 [92-kDa gelatinase/type IV collagenase (gelatinase B)] but not MMP-2 [72-kDa gelatinase/type IV collagenase (gelatinase A)], MMP-3 (stromelysin-1) or MMP-7 (matrilysin). Motility of the tumour cells and adhesion to cultured endothelial cells were slightly increased by the TNFα treatment up to 1.6-fold and 1.4-fold, respectively, while the growth rate was decreased. These results suggest that upregulation of MMP-9 together with enhanced motility and endothelial adhesion contribute to the increased metastatic ability of OST cells induced by TNFα treatment.
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