MiR-638 serves as a tumor suppressor by targeting HOXA9 in glioma

D.-H. Zheng, X. Wang, L.-N. Lu, D.-L. Chen, J.-M. Chen, F.-M. Lin, X.-B. Xu

Department of Neurosurgery, Shunde Hospital, Southern Medical University, The First People’s Hospital of Shunde Foshan, Foshan, China. xiaobingxu2006@sina.com

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• Oncology

OBJECTIVE: MiR-638 is constantly downregulated and serves as a tumor suppressor in various cancers. Its role in gliomas remains unclear. This study is designed to investigate the clinical significance and the pathogenic role of miR-638 in human gliomas.

PATIENTS AND METHODS: Quantitative Real-time PCR was performed to analyze the expression of miR-638 in the tumor and adjacent tissues of 24 glioma patients. The association between the expression of miR-638 and clinical features were examined. Survival of patients was studied by Kaplan-Meier curves. The impact of miR-638 on cell growth and apoptosis was determined by CCK-8 assay, colony formation assay, cell cycle analysis and Annexin V-FITC-PI apoptosis assay. The effect of miR-638 on HOXA9 was determined by luciferase assay and Western blot. The effect of miR-638 and HOXA9 on expression of oncogenes, Cyclin D1 and C-MYC was determined by Western blot.

RESULTS: MiR-638 expression was constantly downregulated in glioma tumor tissue, which is negatively correlated with the WHO grade. MiR-638 expression was associated with clinical features such as tumor size, KPS score and WHO grade. Patients with low miR-638 had a worse overall survival than those with high expression. Experimentally, miR-638 directly targeted HOXA9 to suppress its expression, leading to attenuations of cell proliferation, colony formation and cell cycle progression and enhanced basal apoptosis level. MiR-638/HOXA9 axis also suppressed the expression of Wnt/beta-catenin-regulated oncogenes, Cyclin D1 and C-MYC.

CONCLUSIONS: MiR-638 is a constantly downregulated microRNA in gliomas and is associated with its prognosis. MiR-638 regulates cellular malignancy of gliomas through targeting HOXA9. Thus, miR-638/HOXA9 signaling axis may have therapeutic potential in gliomas.

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