Downregulated expression of lncRNA TUBA4B predicts unfavorable prognosis and suppresses glioma progression by sponging miR-183 to regulate SMAD4 expression
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Submission date: 2019-10-23
Final revision date: 2019-12-08
Acceptance date: 2019-12-17
Online publication date: 2020-02-02
Accumulating evidence has proved that long non-coding RNAs (lncRNAs) are involved in progression of glioma. Nevertheless, the role of TUBA4B in glioma remains unclear.

Material and methods:
The expression of the target gene was measured by quantitative RT-PCR. The prognostic role of TUBA4B was analyzed by Meier survival analysis. Cell proliferation, colony formation, apoptosis, cell cycle, migration and invasion were detected by MTS, soft agar colony forming assay, flow cytometry, and transwell assay. The target interaction of the target gene was validated by the luciferase reporter assay, biotin pull-down assay, and RNA immunoprecipitation.

We found that the expression of TUBA4B was lower in glioma tissues and cells. Moreover, patients with a low TUBA4B expression level exhibited poorer prognosis than those with high TUBA4B expression. Meanwhile, ROC analysis revealed that TUBA4B had diagnostic value to distinguish tumor patients from the healthy population. Overexpression of TUBA4B prohibited the malignancy of glioma, such as inhibition of proliferation, decrease of colony formation, arrest of the cell cycle, decline of migration and invasion, and promotion of cell apoptosis. In addition, we found that TUBA4B directly interacted with miR-183 and negatively regulated the expression of miR-183. We also observed that SMAD4 was a downriver target of miR-183 and TUBA4B subsequently exerted its tumor-suppressive effects by coordinating the expression of SMAD4 in glioma.

This study revealed for the first time that TUBA4B could be a tumor suppressor gene in glioma by adjustment of the TUBA4B/miR-183/SMAD4 axis, which may provide a useful prognostic biomarker and promising therapeutic target for glioma treatment.