ABSTRACT
【Objective】 To investigate the expression and biological role of miR-139-5p in glioblastoma and the regulatory effect of miR-139-5p on DNA methyltransferase 1 (DNMT1). 【Methods】 qRT-PCR was used to detect the expression of miR-139-5p in glioblastoma tumor tissue, paired paracancerous tissue, human normal glioma cell line HEB, and human glioma cell line U251. The expression of miR-139-5p in U251 cells was up-regulated by transfection of miR-139-5p mimetics, and the expression of DNMT1 was down-regulated by transfection of DNMT1-targeted siRNA (DNMT1-siRNA). The expression of DNMT1 and neurofibromatosis type 2 (NF2) in tissues and cells was detected by qRT-PCR, Western blotting, immunohistochemistry and immunofluorescence. The cell counting kit-8 (CCK-8), flow cytometry and Matrigel Transwell were used to evaluate the proliferation, apoptosis and invasion ability of U251 cells. 【Results】 Compared with paracancerous tissues or HEB cells, miR-139-5p expression in glioblastoma tissues and U251 cells was suppressed (P<0.05). Compared with control cells, transfection of miR-139-5p mimic significantly down-regulated the expression of DNMT1 and up-regulated the expression of NF2 (P<0.05). Compared with control cells, transfection of DNMT1-siRNA significantly promoted the expression of NF2 (P<0.05). Transfection of miR-139-5p mimetics or DNMT1-siRNA significantly induced U251 cell apoptosis and inhibited cell invasion (P<0.05). 【Conclusion】 miR-139-5p plays an anti-cancer role in glioblastoma, and it inhibits tumor proliferation and metastasis by targeting negative regulation of DNMT1.
ABSTRACT
Mutations in the NF2 tumor suppressor gene cause neurofibromatosis type 2, an autosomal dominant inherited syndrome predisposed to the multiple tumors of the nervous system. Merlin, the NF2 gene product was reported to block Ras-mediated cell transformation and represses Ras-induced expression of cyclin D1. However, the potential mechanism underlying the anti-Ras function of merlin on the cyclin D1 is still unclear. In this study, we investigated whether merlin decreases Ha-ras-induced accumulation of cyclin D1 at the transcriptional level, and demonstrated that merlin suppressed Ras-induced cyclin D1 promoter activity mediated by the cyclic AMP-responsive element (CRE) in SK-N-BE (2) C neuroblastoma cells. Furthermore, we found that merlin attenuated active Ras and forskolin-induced CRE-driven promoter activity. These results suggest that the transcriptional repression of the cyclin D1 expression by merlin may contribute to the inhibition of Ras-induced cell proliferation