Targeted regulation of microRNA-138 on EZH2 expression and its effect on invasion and migration of thy-roid carcinoma cells

YANG Feiliang; PENG Qiong; RONG Ling

doi:10.3969/j.issn.1009-0460.2019.11.002

Abstract：Objective To investigate the effect of microRNA-138 (miR-138) on the targeting regulation of enhancer of Zeste homolog 2 (EZH2) and the invasion and migration of thyroid cancer 8505C cells. Methods The miR-138 expression and its regulated biological process in thyroid cancer was analyzed by online miR_pathway. 8505C cells were transfected with miR-138 mimics (Overex-pression group) or negative control sequence (NC group), and the untransfected cells were used as Control group. The miR-138 level was detected by real-time quantitative PCR (QPCR). The proliferation was detected by CCK-8 kit. The rate of scratch healing and number of membrane penetrating cells were investigated by scratch test and Transwell chamber test. The mRNA levels of EZH2, matrix metalloproteinase-9 (MMP-9), Janus kinase 1 (JAK1) and signal transducer and activator of transcription 3 (STAT3) were detected by QPCR. Protein levels of MMP-9, JAK1, phosphorylated JAK1 (p-JAK1), STAT3 and phosphorylated STAT3 (p-STAT3) were an-alyzed by Western blotting. Double luciferase reporter gene experiment was applied to verify the targeting regulation of miR-138 on EZH2. Results MiR_pathway online analysis revealed that miR-138 regulated many biological processes in thyroid cancer and was lower in thyroid cancer tissues than in normal tissues ( P＜0. 05). The miR-138 level in Overexpression group was 12. 657± 2. 263, higher than 1. 025±0. 087 in Control group and 1. 109± 0. 097 in NC group ( P＜0. 05). Compared with the Control group and NC group, the cell proliferation ability of the Overexpression group decreased after 24 and 48 h transfection (P＜0. 05). The scratch healing rate and number of membrane piercing cells in the Overexpression group were ( 22. 571 ± 2. 168)% and 152. 3 ± 16. 5, lower than (59. 424±3. 624)% and 287. 4±17. 5 in Control group and (61. 280±4. 035)% and 278. 5±16. 3 in NC group ( P＜0. 05). MiR-138 mimics had an inhibitory effect on the relative luciferase activity of the 3’ untranslated region of EZH2 wild type (P＜0. 05), but had no effect on the mutant (P＞0. 05). Compared with other two groups, the levels of MMP-9, EZH2, p-JAK1 and p-STAT3 in Overex-pression group decreased (P＜0. 05), but there was no significant difference in the levels of JAK1 and STAT3 (P＞0. 05). No signifi-cant difference was observed on the above indices between Control group and NC group (P＞0. 05). Conclusion MiR-138 exhibits a pattern of low expression in thyroid cancer, and this miRNA can inhibit the proliferation, invasion and migration of thyroid cancer, which may be related to the targeted regulation of EZH2 and JAK1／STAT3／MMP-9 pathway. MiR-138 has the potential as a candidate target for thyroid cancer treatment.