Abstract
Matrix metalloproteinases (MMPs) play a crucial role in tumor cell invasion and metastasis. Expression of MMPβ1 has been reported as a prognostic predictor of recurrence in human chondrosarcoma, and studies using human chondrosarcoma cell lines indicate that MMPβ1 expression levels correlate with in vitro invasiveness. These observations suggest that MMPβ1 activity has a central role in cell egress from the primary tumor at an early step in the metastatic cascade. In this study, siRNA was used to investigate whether knock down of the MMPβ1 gene could be used to inhibit invasiveness in a human chondrosarcoma cell line. The inhibitory effect of siRNA on endogenous MMPβ1 gene expression and protein synthesis was demonstrated via RTβPCR, Northern blotting, Western blotting, collagenase activity assay, and an in vitro cell migration assay. The siRNA inhibited MMPβ1 expression specifically, since it did not affect the expression of endogenous glyceraldehyde phosphate dehydrogenase (GAPDH) nor other collagenases. Most importantly, the siRNA mediated reduction in MMPβ1 expression correlated with a decreased ability of chondrosarcoma cells to invade a Type I collagen matrix. The reduction of invasive behavior demonstrated by human chondrosarcoma cells transfected with MMPβ1 siRNA and the specificity of this inhibition supports the hypothesis that this metalloproteinase molecule is involved in initiation of chondrosarcoma metastasis. Β© 2004 WileyβLiss, Inc.