Inhibition of human osteosarcoma cell migration and invasion by a gene silencer, pyrrole-imidazole polyamide, targeted at the human MMP9 NF-κB binding site

Osteosarcoma is one of the most prevalent bone tumors, occurring mostly in adolescence. However, no noticeable progress has been achieved in developing new therapeutic agents for this disease. Matrix metal-loproteinase 9 (MMP9), a type IV collagenase, is a known anticancer target and is overexpressed in osteosar-comas. MMPs can degrade components of the extracellular matrix and are known to be involved in tumor invasion and metastasis. In the present study, we designed and synthesized a pyrrole-imidazole polyamide (HN.49), a gene-silencing agent that specifically targets the nuclear factor-kappa B (NF-κB) binding site of the human MMP9 promoter. We then examined the effect of HN.49 on the enzyme activity of MMP9 and the migration activity of osteosarcoma cells in vitro. It was clearly shown that HN.49 polyamide reduced the expression level of MMP9 mRNA and the enzymatic activity of MMP-9 in SaOS-2 cells. Moreover, HN.49 polyamide inhibited migration and invasion by SaOS-2 cells in in vitro wound-closure and matrigel-invasion assays. These results indicate that HN.49 may be a potential therapeutic agent for inhibiting the invasion and metastasis of osteosarcoma.