microRNA-9 targets matrix metalloproteinase 14 to inhibit invasion, metastasis, and angiogenesis of neuroblastoma cells.

Matrix metalloproteinase (MMP)-14 is the only membrane-anchored MMP that plays a critical role in tumor metastasis and angiogenesis. However, the mechanisms underlying MMP-14 expression in tumors still remain largely unknown. In this study, MMP-14 immunostaining was identified in 29/42 neuroblastoma tissues, which was correlated with clinicopathologic features and shorter patients' survival. In subtotal 20 neuroblastoma cases, microRNA 9 (miR-9) was downregulated and inversely correlated with MMP-14 expression. Bioinformatics analysis revealed a putative miR-9-binding site in the 3'-untranslated region (3'-UTR) of MMP-14 mRNA. Overexpression or knockdown of miR-9 responsively altered both the mRNA and protein levels of MMP-14 and its downstream gene, vascular endothelial growth factor, in cultured neuroblastoma cell lines SH-SY5Y and SK-N-SH. In an MMP-14 3'-UTR luciferase reporter system, miR-9 downregulated the luciferase activity, and these effects were abolished by a mutation in the putative miR-9-binding site. Overexpression of miR-9 suppressed the invasion, metastasis, and angiogenesis of SH-SY5Y and SK-N-SH cells in vitro and in vivo. In addition, the effects of miR-9 on MMP-14 expression, adhesion, migration, invasion, and angiogenesis were rescued by overexpression of MMP-14 in these cells. Furthermore, anti-miR-9 inhibitor or knockdown of MMP-14 respectively increased or inhibited the migration, invasion, and angiogenesis of neuroblastoma cells. These data indicate that miR-9 suppresses MMP-14 expression via the binding site in the 3'-UTR, thus inhibiting the invasion, metastasis, and angiogenesis of neuroblastoma. ©2012 AACR.