Controlled expression of matrix metalloproteinase 9 promotes expression of invasive phenotype of human melanoma cells

To investigate the correlation between matrix metalloproteinase 9 (MMP-9) expression and tumor metastasis, and explore the potential application of controlled expression of target gene in tumor gene therapy.One self-contained tetracycline-regulated retroviral vector containing sense cDNA of MMP-9 was constructed and transfected into an early-stage human melanoma cell line WM35, which did not express MMP-9. In vitro tests such as growth rate, MTT method, 3H-thymidine incorporation, colony forming ability in soft agar, in vitro invasion assay in Boyden chambers, as well as zymography and Western Blot experiment were used to analyze expression of MMPs and in vitro behavior of tumor cells before and after gene transfection.In the presence of exogenous tetracycline, the expression of the transfected MMP-9 were under detectable level and no significant changes in cell behaviors were found when compared with vector-transfected control cells. But when the tetracycline was withdrew from the medium, the expression and activity of MMP-9 were significantly increased. The capacity of in vitro growth, colony forming ability in soft agar, invasion through Matrigel were enhanced remarkably.Transfection of sense MMP-9 can enhance growth and invasion of melanoma cells, further confirming its important role in tumor invasion and metastasis.PubMed017-113