The Expression of Matrix Metalloproteinase-9 and Tumor Angiogenesis in Human Osteosarcoma

ABSTRACT

BACKGROUND: Matrix metalloproteinase-9 (MMP-9) is a matrix-degrading enzyme that's believed to play a crucial role not only for tumor invasion and metastasis, but also for a variety of stromal reactions, including neovascularization. The aim of this study was to investigate the expression of MMP-9 and to compare its expression with the angiogenesis activity in human osteosarcoma. METHODS: Archival tumor tissue samples from 20 patients with osteosarcoma were analyzed by performing immunohistochemistry for the expression of MMP-9 and CD34. The vascularity was measured as the average microvascular density (MVD) of the CD34-positive vessels. The clinical information was obtained through searching the computerized retrospective database from the tumor registry. RESULTS: MMP-9 was expressed in 90% (18/20) of the tumors we examined. The MVD ranged from 10.5 to 179.7 with a mean of 64.9. There was no significant correlation between the MMP-9 expression and the MVD (p=.613). The MMP-9 expression was not associated with any of the clinicopathologic variables, whereas the MVD showed an increasing tendency according to the metastasis status (p=.073). CONCLUSIONS: We demonstrated that MMP-9 activation is likely to occur in human osteosarcoma. However, there was no direct involvement of MMP-9 with tumor angiogenesis. It is noteworthy that MVD may aid physicians to predict the presence of distant metastasis in osteosarcoma patients.