Up-regulation of miR-182 by β-catenin in breast cancer increases tumorigenicity and invasiveness by targeting the matrix metalloproteinase inhibitor RECK

Background: MiR-182 is a member of the miR-183 cluster located at human chromosome 7q32 region and is up-regulated in human cancers. We study the regulation of miR-182 expression and its oncogenic role. Methods: MiR-182 level was investigated by real-time reverse transcription-PCR. Chromatin immunoprecipitation assay was used to confirm promoter binding of transcription factors. The correlation between miR-182 and RECK was analyzed by Western blotting, real-time RT-PCR and 3'-untranslated region reporter assay. Zymography, matrix metalloproteinase activity, invasion and colony formation were used to study the tumorigenic activity. Results: MiR-182 is over-expressed in human breast tumor tissues and cell lines. Inhibition or knockdown of beta-catenin reduced miR-182 level in MDA-MB-231 cells. ChIP assay confirmed the binding of beta-catenin on miR-182 promoter. Anti-miR-182 increased the MMP inhibitor RECK protein in MDA-MB-231 cells while pre-miR-182 reduced RECK protein but not mRNA in normal mammary epithelial H184B5F5/M10 cells. Restoration of RECK protein by anti-miR-182 attenuated MMP-9 activity, cell invasion and colony formation. Ectopic expression of miR-182 inhibited restoration of RECK protein by beta-catenin inhibitor indicating miR-182 is important for beta-catenin-induced down-regulation of RECK. An inverse association between miR-182 and RECK was demonstrated in breast tumor tissues. Conclusions: We provide evidence that miR-182 is up-regulated by beta-catenin signaling pathway in breast cancer and its up-regulation increases tumorigenicity and invasiveness by repressing RECK. General significance: Our data demonstrate for the first time that miR-182 expression is controlled by beta-catenin. In addition, we identify a new miR-182 target RECK which is important for miR-182-induced tumorigenesis. (C) 2013 Elsevier B.V. All rights reserved.