[The Mechanism Study on Histone Acetylation Activating Glioblastoma-derived Neurotrophic Factor Transcription].

OBJECTIVE: To study the regulation role and mechanism of protein acetylation on the expression of glioblastoma-derived neurotrophic factor (GDNF) in human glioma. METHODS: Six normal brain tissue samples, six low-grade glioma brain tissue (LG-glioma), and six high-grade glioma brain tissue (HG-glioma) were collected for study. Human glioma U251 cells were treated with histone acetylase inhibitor and histone deacetylase inhibition. The mRNA level of GDNF in glioma and normal controls was detected by Real-time PCR. H3K9 acetylation level of cAMP-response element binding protein (CREB) binding region on GDNF promoter and the ability of CREB combining to GDNF promoter were detected by ChIP-PCR. The effects of histone acetylase and deacetylase inhibitors on transcription factor binding ability and GDNF expression were detected. RESULTS: The mRNA level of GDNF in HG-glioma was significantly higher than those in normal brain tissue and LG-glioma (P < 0.01). The H3K9 acetylation level of GDNF promoter region in the glioma was increased compared to that in the normal brain tissue (P < 0.01), and the acetylation level in CREB-binding region on the GDNF promoter was higher than that in the non-CREB-binding region (P < 0.01). The binding activity of CREB and GDNF promoter in HG-glioma was higher than those in normal brain tissue and LG-glioma (P < 0.05). After treatment of U251 cells with histone acetyltransferase inhibition, the level of acetylation in CREB-binding region on GDNF promoter, the binding activity of CREB and GDNF promoter was decreased, and GDNF transcription and expression were down-regulated, while histone deacetylase inhibitors had the opposite effect (P < 0.01). CONCLUSION: Histone acetylation promotes the transcription expression of GDNF in glioma by promoting the binding of transcription factor CREB to the promoter region of GDNF gene.

Long non­coding RNA DLEU1 promotes cell proliferation of glioblastoma multiforme.

Glioblastoma multiforme (GBM) is the most common malignant tumor with high morbidity and mortality. This study investigated the role of long non­coding RNAs (lncRNAs) in glioblastomagenesis progression. Using the GSE2223 and GSE59612 datasets, and RNA sequencing data of GBM from The Cancer Genome Atlas, differentially expressed (DE) genes including DE messenger RNAs (DEmRNAs) and DElncRNAs between GBM and normal controls were identified. Based on the competing endogenous RNA hypothesis, DElncRNA­micro RNA (miRNA)­DEmRNA interactions were obtained by target gene prediction. Gene Ontology (GO) and Kyoto Encyclopedia of Gene and Genomes pathway analysis of DEmRNAs in the DElncRNA­miRNA­DEmRNA network was performed. Expression and function analyses of DElncRNAs were performed by reverse transcription­polymerase chain reaction (RT­PCR) and an established viability assay, respectively. In total, 712 DE genes were identified. Significant upregulation of lncRNA deleted in lymphocytic leukemia 1 (DLEU1) was revealed in GBM and a number of other types of cancer. DLEU1 interacted with 315 miRNAs and 105 DEmRNAs. The DEmRNAs were mainly enriched in tumorigenesis­associated GO terms (angiogenesis, positive regulation of cell proliferation, positive regulation of fibroblast apoptotic processes and regulation of neutrophil migration) and pathways (Hippo signaling pathway, cancer pathways, and Wnt signaling pathway). Correlation analysis revealed that mRNA TNF receptor associated factor 4 (TRAF4) was associated with DLEU1 expression. RT­PCR demonstrated that the expression levels of DLEU1 and TRAF4 were increased in GBM tissues. Small interfering RNA demonstrated that silencing DLEU1 downregulated TRAF4. The viability of GBM cells was significantly decreased following RNA interference with DLEU1 and TRAF4 production. The results demonstrate that DLEU1 and TRAF4 is highly expressed in GBM tissues and promotes proliferation of GBM cells. It may act as a competing endogenous RNA and influence tumorigenesis of GBM.