RNAi-mediated MMP-9 silencing inhibits mouse melanoma cell invasion and migration in vitro and in vivo

MMP‐9 participates in tumour growth, invasion, metastasis and vascularisation. Thus, inhibition of MMP‐9 may be involved in the process of tumourigenesis. We have investigated the effect of RNAi‐mediated MMP‐9 silencing on inhibiting invasion and migration of mouse melanoma cell B16. A specific and optimised siRNA vector was used to target MMP‐9 mRNA synthesis in B16 cells. Changes of invasion and migration capability of B16 cell were examined after transfection at different time, and a footpad tumour model was performed to measure the effect of MMP‐9 siRNA on melanoma tumourigenesis in vivo. In vitro, down‐regulation of MMP‐9 expression significantly inhibited B16 cell invasion and migration. In vivo, intratumoural injection of plasmid DNA expressing MMP‐9 siRNA every 3 days for three times remarkably inhibited melanoma growth and also suppressed tumour metastasis. The results indicate that RNA‐mediated targeting of MMP‐9 may have promising applications for the treatment of melanoma.