Effect of microRNA-218 targeting SOX5 on the growth and invasiveness of glioblastoma cells

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Objective To observe effect of microRNA-218(miR-218)targeting SOX5 on the growth and invasiveness of glioblastoma cells. Methods U87 glioma cell lines were cultured, and they were divided into a control group, a nonsense sequence group and a miR-218 mimics transfection group. Forty glioma tissue specimens and 35 normal brain tissue samples were selected. The biological information method and the luciferase report system were used to verify that SOX5 was the direct acting target of miR-218. The effect of miR-218 on mRNA and protein expression of SOX5 in U87 cells, glioma tissue and their normal brain tissue were detected by RT-PCR and Western blot. After overexpressing miR-218 in U87 cells, the changes of U87 cell phenotype were detected by using the MTT experiment and Tanswell experiment. Results Compared with the control and the nonsense sequence groups, the relative expression quantity of miRNA-218 increased about 42.23 times in the miRNA-218 mimics transfection group. The results of MTT assay showed that the growth of glioma cells was inhibited significantly after overexpreesing miRNA-218. The cell proliferation rate of at day 5 was only 49.2%. The results of Transwell assay showed that the number of cells passing through the Transwell chambers was 13.0±2.1. It was lower than 35.0±2.3 and 32.0±3.1 in the control and the nonsense sequence groups(all P<0.05). The biological information predicted that the SOX5 was one of the target genes of miR-218. UTR contained the binding site of miR-218 in SOX5 3′. The dual luciferase assays indicated that SOX5 was the direct acting target of miR-218. After overexpressing miR-218, RT-PCR and Western blot showed that the expression of SOX5 mRNA and protein in the miR-218 mimics transfection group was significantly lower than that the control and the nonsense sequence groups. There was significant difference(P<0.01). After silencing SOX5, the results of the MTT assay showed that the cell increment rate of the siRNA-SOX5 group at day 5 of cell culture was only 51.0% in the siControl group. The Transwell assay analysis showed that the number of cells passing through Transwell chambers in the siRNA-SOX5 group was 12.0±1.3, and it was lower than 23.0±2.0 in the siControl group(P<0.05). Conclusions SOX5 is the target gene of miR-218 and it was negatively regulated by it. miR-218 may play an important role in pathogenesis of glioma through targeting SOX5. Key words: Glioma; MicroRNAs; SOX5; U87 cell