CircGLIS3 promotes high-grade glioma invasion via modulating Ezrin phosphorylation

High-grade glioma is highly aggressive and malignant, resistant to combined therapies and easy to relapse. A better understanding of circRNA biological function in high-grade glioma might contribute to the therapeutic efficacy. Here, a circRNA merely up-regulated in high-grade glioma, circGLIS3 (hsa_circ_0002874, originating from exon 2 of GLIS3), was validated by microarray and qRT-PCR. Functional experiments uncovered that up-regulation of circGLIS3 promoted glioma cell migration and invasion, and showed aggressive characteristics in tumor-bearing mice. Fluorescence in situ hybridization, RNA pull-down, RNA immunoprecipitation and immunohistochemical staining showed that circGLIS3 could promoted Ezrin T567 phosphorylation. Further investigation showed that circGLIS3 could be excreted by glioma through exosomes and induced endothelial cells angiogenesis. This study indicates that circGLIS3 is up-regulated in high-grade glioma and contributes to the invasion and angiogenesis of glioma via promoting Ezrin T567 phosphorylation. Overall design: mRNA profiles of cell line U251 after transfected with sh-circGLIS3 or sh-NC lentivirus

高级别胶质瘤（High-grade glioma）是一类高度侵袭性、恶性程度极强的肿瘤，对联合治疗存在耐药性且极易复发。深入解析环状RNA（circRNA）在高级别胶质瘤中的生物学功能，或可提升其临床治疗效果。本研究通过微阵列（microarray）与实时定量聚合酶链反应（qRT-PCR）验证了一种仅在高级别胶质瘤中上调的环状RNA——circGLIS3（hsa_circ_0002874，源自GLIS3基因的第2外显子）。功能实验结果显示，circGLIS3的过表达可促进胶质瘤细胞的迁移与侵袭能力，并在荷瘤小鼠模型中表现出侵袭性表型。荧光原位杂交（Fluorescence in situ hybridization）、RNA下拉实验（RNA pull-down）、RNA免疫沉淀（RNA immunoprecipitation）与免疫组化染色（immunohistochemical staining）结果表明，circGLIS3可促进Ezrin蛋白T567位点的磷酸化。进一步机制研究显示，circGLIS3可通过胶质瘤细胞分泌的外泌体（exosomes）释放，并诱导内皮细胞的血管生成过程。本研究证实，circGLIS3在高级别胶质瘤中呈上调表达，通过促进Ezrin T567磷酸化参与胶质瘤的侵袭与血管生成过程。总体设计：转染靶向circGLIS3的短发夹RNA慢病毒（sh-circGLIS3）或阴性对照短发夹RNA慢病毒（sh-NC）后，U251细胞系的信使RNA（mRNA）表达谱。