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  • 1
    ISSN: 1573-7276
    Keywords: invasion ; metalloproteinases ; metastasis ; tissue inhibitors of metalloproteinases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Basement membrane forms widespread barriers to tumor invasion. It has been shown that tumor-secreted, basement membrane-degrading enzymes, namely metalloproteinases (MMPs) play an important role in tumor invasion and metastasis. In this study, we determined the enzymatic activity, content, and mRNA of both the 72 kDa (MMP-2) and 92 kDa (MMP-9) MMPs in primary cultures of human giant-cell tumor of bone (GCT)in vitro and in tissue extracts (in vivo). Gelatin zymography showed the presence of lytic bands at Mr 121000, 92000, and 72000, and these enzymatic activities were inhibited by EDTA, an inhibitor of MMPs. Western blots with antibodies specific for MMP-2 and MMP-9 confirmed the presence of MMP-2 and MMP-9 bothin vitro andin vivo, but GCT cells at late passage showed only MMP-2. Northern blots using labeled cDNA probes specific for these molecules revealed the presence of 3.1 kb transcript for MMP-2 and a 2.9 kb transcript for MMP-9. Using specific antibodies to 72 kDa and 92 kDa type IV collagenases, we studied their cellular distribution by immunohistochemical means. Stronger immunoreactivity was found for 92 kDa type IV collagenase than 72 kDa type IV collagenase in the giant cells. It appears, therefore, that MMP-9 may play an important role in the malignant behavior of GCTs and suggests a potential therapeutic role for protease inhibitors in attempting to minimize the invasive behavior of GCTs.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1573-7276
    Keywords: cytokines ; giant cell tumor ; metalloproteinases ; stromal cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Matrix metalloproteinases (MMPs) play an important regulatory role in tissue morphogenesis, cell differentiation, tumor invasion and metastasis. Several authors have reported a direct correlation between the production of 72 kDa (MMP-2) and 92 kDa (MMP-9) type IV collagenases/gelatinases and the metastatic potential of cancer cells. Recently, we have identified the expression of both MMP-2 and MMP-9 in primary cultures of human giant cell tumor (GCT) of bone in vitro, and in tissue extracts in vivo. Interestingly, MMP-9 is not secreted by late-passaged GCT cells. It is possible that the production of MMP-9 is regulated by certain factor(s) secreted by the multinucleated giant cells in the primary culture. In order to test this hypothesis, the effect of primary-culture-conditioned medium on the expression of MMP-9 by late-passaged mononuclear stromal cells was examined. Adding conditioned medium from the primary GCT culture to the late-passaged stromal cells induced MMP-9, as evidenced by the presence of lytic bands at Mr 92000 and 72000 on a gelatin zymogram. These enzyme activities were inhibited by EDTA, a well-known inhibitor of the MMPs. We confirmed these results by Western blotting using specific antibodies and RT-PCR for MMP-2 and MMP-9. Immunofluorescence studies with specific antibodies to MMP-9 further confirmed its expression by the passaged stromal cells cultured in the primary-culture-conditioned medium. The data indicate that MMP-2 and MMP-9 are produced by the mononuclear stromal cells when cultured in GCT primary-culture-conditioned medium. This suggests that multinucleated giant cells in primary cultures secrete a factor(s) that stimulates stromal cells to produce MMP-9, which, in turn, may contribute to the aggressive behavior of GCT.
    Type of Medium: Electronic Resource
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