| Research Abstract |
In the treatment of malignant bone and soft tissue tumors, distant metastasis still remains a problem. We have established in vitro invasion assay system to investigate the molecular mechanisms by which the tumor cell can metastasize to distant organs.
Tumor cell invasion to the basement membrane is one of the crucial steps for cancer metastasis, consisting of attachment to the basement membrane, matrix degradation and tumor cell motility. The degradation of matrix is mediated by the balance between degradation enzymes, matrix metalloproteinase (MMP), and their inhibitors, tissue inhibitor of metalloproteinase (TIMP). In this study, we investigated and found that (1) the ability of invasion to basement membrane of osteosarcoma cell can be enhanced by TNF-a, which is mediated by activation of NF-KB in the cells, (2) the antioxidants can block the activation of NF-KB by TNF-a and subsequently inhibit the invasion of the osteosarcoma cells. (3) A newly synthesized, oral-administrable MMP i
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nhibitor, OPB-3206, and inhibit angiogenesis, tumor growth and experimental metastasis in vivo, indicating that inhibition of MMP activity is essential to control tumor growth and metastasis. (4) RhoA, a small GTP-binding protein, is play important roles to control cell shape and motility. Since 1-oieoyl lysophosphatidic acid (LPA) specifically active RhoA, we treated of osteosarcoma cells with LPA. The treatment of LPA induces stressfiber formation, cell shape alteration, expression of membrane type-1 MMP (MT1-MMP), TIMP-2 and active from MMP-2, and invasion of the cells. (5) The botulinum toxin C3, inhibitor of RhoA, and Y27632, an inhibitor of Rho-associated kinase p160ROCK are both able to inhibit the effects of LPA, indicating that RhoA controls the activity of MMP and invasion of the osteosarcoma cells. (6) MT1-MMP and TIMP-2 are essential for the activation of MMP-2 and important for invasive phenotype of tumor cells. The expression of MT1-MMP, TIMP-2 and MMP-2 has significant correlation with the histologic stages of human chondrosarcoma and matrix destruction by the sarcoma cells. Less
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