407039

MIR33A

OBJECTIVE: To investigate the effect of epithelial-mesenchymal transition (EMT) on the expression of microRNAs (miRNAs) in lung cancer A549 cells. METHODS: Transforming growth factor beta-1 (TGF-beta 1) in different concentrations was used to induce EMT in lung cancer A549 cells. The morphological changes were observed under phase-contrast microscope. The changes of EMT-related proteins were analyzed by Western blot. The changes of miRNAs expression after EMT were detected by microRNA (miRNA) array. Real time quantitative RT-PCR was applied to verify the reliability of miRNA array results. RESULTS: The lung cancer A549 cells became elongated and the cell-cell junction became loose after EMT. The epithelial protein marker E-cadherin was down-regulated and the mesenchymal protein markers vimentin and fibronectin up-regulated. There were 51 miRNAs showing statistically significant changes of expression more than double (P<0.05) after EMT. Among them 18 were up-regulated and 33 down-regulated. Of them, mir-33a was down-regulated by 92.8% and mir-193a-3p by 86.5%. Real time quantitative RT-PCR showed that mir-33a was down-regulated by 73.1% and mir-193a-3p by 56.6%. CONCLUSION: epithelial-mesenchymal transition has effects on the expression of miRNAs, and miRNAs may regulate the invasion and metastasis of lung cancer cells via EMT.

BACKGROUND/AIMS: Preventing cell metastasis is an effective therapeutic strategy to treat osteosarcoma and improve prognosis. Statins have been found to have anticancer effects in addition to their cholesterol-lowering action. As a new target of statins, cysteine-rich 61 (CYR61) was recently identified to promote cell migration and metastasis in osteosarcoma. However, the underlying mechanisms mediating the regulation of CYR61 expression by statins remain unknown. METHODS: Human osteosarcoma cell lines MG63 and SaOS2 were used to clarify the effect of lovastatin on CYR61 expression. Real-time PCR was performed to detect mRNA or microRNA (miRNA) levels and western blot was performed to detect protein levels. Cell invasive ability was determined using Transwell assays. Lentivirus encoding CYR61 cDNA or sterol regulatory element-binding protein 2 (SREBP-2) shRNA was used to upregulate CYR61 expression or downregulate SREBP-2 expression. Binding of the CYR61 3' untranslated region (UTR) and miR-33a was analyzed by luciferase reporter assay. RESULTS: We found that lovastatin treatment decreased CYR61 expression, inhibited cell invasion and altered epithelial-to-mesenchymal-transition (EMT)-related protein expression, while CYR61 overexpression abolished the effect of lovastatin. Moreover, lovastatin increased the expression of SREBP-2 and miR-33a, which were then downregulated by SREBP-2 silencing. Bioinformatics analysis indicated that the CYR61 3'UTR harbored a potential miR-33a binding site and luciferase reporter assay demonstrated that CYR61 was a target of miR-33a in osteosarcoma cells. Furthermore, miR-33a could inhibit cell invasion and alter EMT-related protein expression. SREBP-2 silencing or miR-33a inhibitor upregulated CYR61 expression and reversed the effects of lovastatin on cell invasion and EMT-related proteins. CONCLUSION: Our findings suggest lovastatin suppresses osteosarcoma cell invasion through the SREBP-2/miR-33a/CYR61 pathway.CI - (c) 2018 The Author(s). Published by S. Karger AG, Basel.