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Background/Aims: Glial cell line-derived neurotrophic factor (GDNF) is an important factor promoting invasive glioma growth. This study was performed to reveal a unique mechanism of glioma cell proliferation and migration. Methods: Human U251 glioma cells were used to screen the optimal GDNF concentration and treatment time to stimulate proliferation and migration. MicroRNA (MiRNA) expression profiles were detected by microarray and confirmed by real-time polymerase chain reaction (PCR). The target genes of differentially expressed miRNAs were predicted by miRWalk, and those targeted by multiple miRNAs were screened with Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. A regulatory miRNA network was constructed using ingenuity pathway analysis (IPA). Target gene expression of differentially expressed miRNAs was examined by real-time PCR or mRNA microarray. Results: The results show that 50 ng/mL GDNF for 24 h significantly promotes U251 glioma cell proliferation and migration (P < 0.05). Seven miRNAs (hsa-miR-194-5p, hsa-miR-152-3p, hsa-miR-205-5p, hsa-miR-629-5p, hsa-miR-3609, hsa-miR-183-5p, and hsa-miR-487b-3p) were significantly up-regulated after GDNF treatment (P < 0.05). These miRNAs are primarily involved in signal transduction, cell adhesion and cell cycle through mitogen-activated protein kinase (MAPK) signaling, focal adhesion and glioma signal pathways. Five of these miRNAs (hsa-miR-194-5p, hsa-miR-152-3p, hsa-miR-205-5p, hsa-miR-183-5p, and hsa-miR-487b-3p) co-regulate TP53 and Akt. mRNA expression levels of four genes co-targeted by two or more up-regulated miRNAs were significantly decreased after GDNF treatment (P < 0.05). Conclusion: GDNF treatment of U251 glioma cells significantly increased the expression of seven miRNAs involved in cell adhesion and the cell cycle. [ABSTRACT FROM AUTHOR]

Abnormally high transcription of the glial cell-line derived neurotrophic factor ( gdnf ) gene in glioma cells is related to the hyperacetylation of histone H3 lysine 9 (H3K9) in its promoter region II, but the mechanism remains unclear. There are three consecutive putative binding sites for the transcription factor early growth response protein 1(Egr-1) in promoter region II of the gdnf gene, and Egr-1 participates in gdnf gene transcription activation. Here we show that the acetylation level of H3K9 at Egr-1 binding sites in gdnf gene promoter region II in rat C6 astroglioma cells was significantly higher than that in normal astrocytes, and the binding capacity was also significantly higher. In C6 astroglioma cells, gdnf gene transcription significantly decreased after Egr- 1 knock-down. In addition, the deletion or mutation of the Egr-1 binding site also significantly down-regulated the activity of promoter region II of this gene in vitro. When curcumin decreased the acetylation level of H3K9 at the Egr-1 binding site, the binding of Egr-1 to promoter region II and GDNF mRNA levels significantly decreased. In contrast, trichostatin A treatment significantly increased H3K9 acetylation at the Egr-1 binding site, which significantly increased both the binding of Egr-1 with promoter region II and GDNF mRNA levels. In this context, knocking down Egr- 1 significantly reduced the elevation in gdnf gene transcription. Collectively, our results demonstrate that the hyperacetylation of H3K9 at Egr-1 binding sites in promoter region II of the gdnf gene can up-regulate the binding of Egr-1 to increase gdnf gene transcription in glioma cells. [ABSTRACT FROM AUTHOR]