Long non-coding RNA LINC00526 represses glioma progression via forming a double negative feedback loop with AXL

Glioma is the most common primary intracranial carcinoma with extremely poor prognosis. The significances of long non-coding RNA (lncRNA) involved in glioma have been started revealed. However, the expression, roles and molecular mechanisms of most lncRNAs in glioma are still unknown. In this study, we identified a novel lncRNA LINC00526, which is significantly low expressed in glioma. Low expression of LINC00526 is correlated with aggravation and poor survival in glioma. Functional assays revealed that ectopic expression of LINC00526 inhibits glioma cell proliferation, migration, and invasion. LINC00526 silencing promotes glioma cell proliferation, migration and invasion. Mechanistically, we found that LINC00526 directly interacts with EZH2, represses the binding of EZH2 to Axl promoter, attenuates the transcriptional activating roles of EZH2 on Axl, and therefore represses Axl expression. Via repressing Axl, LINC00526 further represses PI3K/Akt/NF-κB signalling. Intriguingly, we identified that NFKB1 and NFKB2 directly binds LINC00526 promoter and represses LINC00526 transcription. We further found that via activating NF-κB signalling, Axl represses LINC00526 transcription. Therefore, LINC00526/EZH2/Axl/PI3K/Akt/NF-κB form a feedback loop in glioma. Analysis of the TCGA data revealed that the expression of LINC00526 is inversely correlated with that of Axl in glioma tissues. In addition, functional rescue assays revealed that the tumour suppressive roles of LINC00526 are dependent on the negative regulation of Axl. Collectively, our data identified LINC00526 as a tumour suppressor in glioma via forming a double negative feedback loop with Axl. Our data also suggested LINC00526 as a potential prognostic biomarker and therapeutic candidate for glioma.