FXR1 Promotes The Malignant Biological Behavior Of Glioma Cells Via Stabilizing MIR17HG

Objective: Glioma is the most common primary malignant tumor of the central nervous system.Although the application of advanced surgery,chemotherapy and radiotherapy,patients suffering from glioblastoma meet a median survival of only 12 to 15 months and less than 5% of the patients surviving greater than 5-year.The purpose of this study was to investigate whether RNA binding protein FXR1 and Long non-coding RNAs(lncRNA)MIR17HG affected the malignant biological behavior of glioma cells,and to further analyze its potential mechanism.We further aimed to explore whether FXR1 could promote the expression of TAL1 by negatively regulating miR-346/miR-425-5p via stabilizing MIR17 HG,and promoting malignant biological behavior of glioma cells.Methods: Real-time PCR were conducted to evaluate the expression of MIR17 HG and miR-346,miRNA-425-5p in glioma tissues and cells.Western blot were used to explore the expression of FXR1,TAL1 and DEC1 in glioma tissues and cells.Cell Counting Kit-8,transwell assays,and flow cytometry were performed to investigate the viability,migration,invasion and apoptosis of glioma cells.Inhibition of FXR1,MIR17 HG,DEC1 plasmids,over-expression or inhibition of TAL1,miR-346,miR-425-5p plasmids were transfected into the cells.The mRNA expression of MIR17 HG,TAL1,and miR-346,miR-425-5p was measured by Real-time PCR.The expression of FXR1,TAL1,DEC1 protein was determined by Western blot.(RNA-binding protein immunoprecipitation)RIP and RNA pull down were conducted to investigate whether FXR1 bound to MIR17 HG.Regulation of miR-346/miR-425-5p targeting MIR17 HG,regulation of miR-346/miR-425-5p targeting TAL1 were evaluated by luciferase reporter assay.Chromatin Immunoprecitation(ChIP)assays were employed to ascertain the correlations between TAL1 and MIR17 HG,TAL1 and DEC1.The effects of FXR1 and MIR 17 HG on the growth of transplanted tumors and the survival time of nude mice bearing tumors were examined in nude mice.Results: FXR1 and MIR17HG were upregulated in glioma tissues and cell lines.Downregulation of FXR1 or MIR17 HG resulted in inhibition of glioma cells progression.We also found that FXR1 regulates the biological behavior of glioma cells via stabilizing MIR17 HG.In addition,downregulated MIR17 HG increased miR-346/miR-425-5p expression and MIR17 HG acted as ceRNA to sponge miR-346/miR-425-5p.TAL1 was a direct target of miR-346/miR-425-5p,and played oncogenic role in glioma cells.More importantly,TAL1 activated MIR17 HG promoter and upregulated its expression,forming a feedback loop.Remarkably,FXR1 knockdown combined with inhibition of MIR17 HG resulted in the smallest tumor volumes and the longest survivals of nude mice in vivo.Conclusions: 1.Knockdown of FXR1 significantly decreased the expression of MIR17 HG,inhibit the proliferation,migration and invasion of glioma cells,and promote cell apoptosis.2.Inhibition of MIR17 HG can up-regulate the expression of miR-346 and miR-425-5p, respectively,which can inhibit the proliferation,migration and invasion of glioma cells and promote cell apoptosis.3.Knockdown of MIR17 HG significantly decreased TAL1 expression by increasing miR-346/miR-425-5p,and impaired malignant biological behaviors of glioma cells.4.Overexpression of miR-346/miR-425-5p in glioma cells can significantly reduce the expression of DEC1 and inhibit the malignant biological behavior of glioma cells by down-regulating the expression of TAL1.5.TAL1 binds to the promoter region of MIR17HG/DEC1 to increase its promoter activity.6.FXR1/MIR17HG/miR-346(miR-425-5p)/TAL1/DEC1 axis plays a novel role in regulating the malignant behavior of glioma cells.