Abstract
Membrane type 1 matrix metalloproteinase (MT1-MMP) has been identified as an activator of the proenzyme of matrix metalloproteinase 2 (MMP-2: gelatinase A), and has also been shown to play a crucial role in tumor invasion by activating proMMP2 in both lung and gastric carcinoma. The tissue inhibitor of metalloproteinase 2 (TIMP-2) plus the MT1-MMP complex also plays an important role in the activation of proMMP-2. In this study, the expressions of MT1-MMP, MMP-2 and TIMP-2 were evaluated in 10 enchondromas, 34 conventional chondrosarcomas, 5 clear-cell chondrosarcomas, 7 mesenchymal chondrosarcomas and 8 dedifferentiated chondrosarcomas. The expressions were immunohistochemically visualized on paraffin sections and the levels of expression were assessed semiquantitatively. The extent of staining was assessed by the extent score in order to determine the overall level of expression. The extent scores of MT1-MMP, MMP-2 and TIMP-2 in grade 2 chondrosarcoma were significantly higher than those in either enchondroma or grade 1 chondrosarcoma (P < 0.05). In conventional chondrosarcoma, significant correlations were found between the extent scores of MT1-MMP and MMP-2 (P < 0.001), MT1-MMP and TIMP-2 (P < 0.01), and MMP-2 and TIMP-2 (P < 0.01). The undifferentiated small round tumor cells of mesenchymal chondrosarcoma showed lower positive rates and extent scores for MT1-MMP (2/7, 0.7 +/- 0.5) and MMP-2 (3/7, 0.7 +/- 0.4) than for cartilaginous components of mesenchymal chondrosarcoma [MT1-MMP (4/7, 1.3 +/- 0.5) and MMP-2 (7/7, 1.9 +/- 0.3)] or conventional chondrosarcoma. In dedifferentiated chondrosarcoma, the extent scores of MT1-MMP, MMP-2 and TIMP-2 in low-grade cartilaginous components were not significantly different from those in conventional chondrosarcoma; however, the high-grade anaplastic components showed high extent scores for MT1-MMP, MMP-2 and TIMP-2, compared with the low-grade cartilaginous components of dedifferentiated chondrosarcoma or conventional chondrosarcoma. According to our results, the expression of MT1-MMP as well as that of MMP-2 or TIMP-2 demonstrated a significant correlation with the tumor grade in human cartilaginous tumors. Furthermore, the expressions of MT1-MMP, MMP-2 and TIMP-2 were also found to play a crucial role in invasion in the high-grade components of dedifferentiated chondrosarcoma.