miR-32 inhibits proliferation, epithelial–mesenchymal transition, and metastasis by targeting TWIST1 in non-small-cell lung cancer cells

BACKGROUND By analyzing published microRNA microarray studies, miR-32 was found to be markedly reduced in non-small-cell lung cancer (NSCLC) tissues compared with that in nontumor tissues. However, little is known about its role and molecular mechanism involved in NSCLC development and progression. Here, we report the effect of miR-32 on NSCLC cell proliferation, epithelial-mesenchymal transition (EMT), and metastasis. METHODS Quantitative real-time PCR was performed to detect the expression level of miR-32 in primary NSCLC cases and cell lines. miR-32-overexpressing H1299 and A549 cells were constructed by lipofection transfection. MTT, transwell chamber, and Western blot assays were used to assess the effect of miR-32 on proliferation, EMT, and metastasis of NSCLC cells, respectively. Target prediction and luciferase reporter assays were performed to investigate the targets of miR-32. Tumor formation assay in vivo was performed to investigate the antitumor effect of miR-32. RESULTS An inverse correlation existed between miR-32 expression level and NSCLC cell proliferation, EMT, and metastasis, and upregulation of miR-32 repressed NSCLC cell proliferation, EMT, and metastasis. Moreover, we identified and validated that TWIST1 was a direct target of miR-32, and miR-32 regulated NSCLC cell proliferation, EMT, and metastasis, at least in part via modulation of TWIST1. The animal experiments showed that overexpression of miR-32 inhibited the growth of NSCLC tumors in vivo.