Abstract
MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression by targeting the mRNAs of hundreds of human genes. Variations in miRNA expression levels were shown to be associated with glioma. We have previously found miR-30a-5p overexpression in glioma cell lines and specimens. Bioinformatics analyses predict that several miRNAs, including miR-30a-5p, are involved in the post-transcriptional regulation of SEPT7. SEPT7 is a member of the septin family, which is a highly conserved subfamily of GTPases implicated in exocytosis, apoptosis, synaptogenesis, neurodegeneration and tumorigenesis. Our previous study has also demonstrated that SEPT7 expression is decreased in astrocytic gliomas with different grades and plays a tumor suppressor role. In the present study, we knocked down miR-30a-5p with antisense oligonucleotide (miR-30a-5p AS) in LN229 and SNB19 glioblastoma(GBM) cells, and found that cell growth and invasion were inhibited, while apoptosis was induced. miR-30a-5p AS treated cells showed upregulation of SEPT7 and downregulation of PCNA, cyclin D1, Bcl2, MMP2 and MMP9. In contrast, when miR-30a-5p mimics were transfected into LN229 and SNB19 GBM cells, cell growth and invasion were promoted and the expression of relevant proteins increased. Meanwhile, the effect of miR-30a-5p mimics on glioma cells can be reversed by transfection of SEPT7 construct. Additionaly, miR-30a-5p directly targeting SEPT7 was identified by the reporter gene assay. Our study demonstrates,for the first time, that miR-30a-5p is a bona fide negative regulator of SEPT7 and the oncogenic activity of miR-30a-5p in human gliomas is at least in part through the repression of SEPT7.