MiRNA-506 presents multiple tumor suppressor activities by targeting EZH2 in nasopharyngeal carcinoma

Objective: MiR-506 has been reported to be associated with multiple malignancies, but its roles in nasopharyngeal cancer (NPC) are not fully understood. Our objective is to demonstrate its effects on NPC and the underlying mechanisms. Methods: Totally fifteen pairs of NPC and adjacent non-tumorous tissues were collected for the detection of miR-506 and enhancer of zeste homolog 2 (EZH2) expression. Dual luciferase reporter assay was employed for verifying the relationship between miR-506 and EZH2. The flow cytometry and MTT assays were employed to explore the effects of miR-506 and EZH2 on the cell apoptosis and proliferation, respectively. Wound closure and transwell assays were used to evaluate the cell migration and invasion abilities. Western blotting or RT-qPCR assays were applied to detect the alterations of miR-506, EZH2 and epithelial-mesenchymal transition (EMT) related markers. Morphological changes of cells with EMT were assessed by light microscopy. Results: MiR-506 was significantly decreased and EZH2 was obviously increased in NPC tissues. Overexpression of miR-506 decreased the EZH2 level, promoted apoptosis, inhibited proliferation, invasion and migration of NPC cells. Accordingly, miR-506 overexpression attenuated EMT process of NPC cells as demonstrated by the alterations of EMT-related markers and the morphological changes. In addition, the luciferase assay proved that miR-506 directly targeted EZH2. Furthermore, the overexpression of EZH2 reversed the tumor-suppressive effects induced by miR-506 mimics. Conclusion: MiR-506 acted as a tumor suppressor to promote apoptosis and inhibit invasion and migration via directly targeting EZH2. MiR-506 can be a candidate target for gene therapy against NPC. (C) 2020 Oto-Rhino-Laryngological Society of Japan Inc. Published by Elsevier B.V. All rights reserved.