miR-132 weakens proliferation and invasion of glioma cells via the inhibition of Gli1.

OBJECTIVE: Transcriptional factor Gli1 in Hedgehog signal pathway facilitates epithelial mesenchymal transition (EMT) and is associated with invasion or proliferation of multiple tumor cells. The previous study showed the correlation between miR-132 down-regulation and glioma pathogenesis. We investigated the role of miR-132 in mediating Gli1 expression and in affecting proliferation or invasion of glioma cells.

PATIENTS AND METHODS: Dual luciferase reporter gene assay was used to confirm the targeted regulation between miR-132 and Gli1. Tumor tissues at different pathological grades (grade II, III and IV) were collected from glioma patients, in parallel with brain tissues from contusion surgery. The expression of miR-132 and Gli1 was measured by RT-PCR. Glioma cell line U251 was treated with miR-132 or si-Gli1 followed by measuring the expression of Gli1, E-cadherin, Vimentin and Cyclin D1. In addition, flow cytometry and transwell assay were performed to evaluate cell invasion potency.

RESULTS: Bioinformatics analysis showed the complementary binding sites between miR-132 and 3'-UTR of Gli1 mRNA. Transfection of miR-132 mimic significantly reduced luciferase activity, indicating the targeted regulatory relationship between miR-132 and Gli1 mRNA. Compared with control group, miR-132 expression was decreased and Gli1 level was elevated in glioma tissues, both of which were correlated with the pathological grade. Transfection of miR-132 mimic or si-Gli1 remarkably suppressed the expression of Gli1, Vimentin or Cyclin D1 in U251 cells, up-regulated E-cadherin expression, suppressed cell proliferation and invasion.

CONCLUSIONS: Our data indicated that over-expression of miR-132 could inhibit proliferation or invasion of glioma cells via targeted inhibition of Gli1 expression.