Elevated expression of matrix metalloproteinase-3 in human osteosarcoma and its association with tumor metastasis

Purpose: Matrix metalloproteinase-3 (MMP-3) is one of the several MMPs that is associated with malignant tumors of breast, colon, cervix and lung, where its expression has been correlated with tumor invasion and metastasis. However, the role of MMP-3 in metastasis of osteosarcoma has not yet been explored. Methods: MMP-3 expression in 15 primary and metastatic osteosarcomas with case-matched adjacent non-tumor tissue was assessed by immunohistochemistry and quantitative RT-PCR. Further, MMP-3 mRNA and protein levels were also determined in osteoblast and osteosarcoma cell lines. Additionally, migration and invasion assays were performed in MMP-3 knockdown cells. Results: MMP-3 was expressed in 86.6% (13/15) of the osteosarcoma patients and its expression was significantly higher in metastatic tumors as compared to the primary osteosarcoma tumor tissues. Furthermore, osteosarcoma cell lines showed higher MMP-3 expression as compared to osteoblast cell lines. siRNA-mediated MMP-3 knockdown in osteosarcoma cell lines significantly inhibited their migration and invasion properties. Conclusion: Our results demonstrated that MMP-3 expression is deregulated in osteosarcomas and this potentially contributes to metastasis and might be a promising marker for the prognosis and therapy of metastatic osteosarcoma.