ABSTRACT
@#[Abstract] Objective：To explore the regulatory effect of miR-9 on biological behaviors of small cell lung cancer (SCLC) cells by targeting zinc finger E-box binding homeobox 2 (ZEB2), and to analyze the role of miR-9 in SCLC and its possible mechanism. Methods: qPCR, WB and immunohistochemistry methods were used to detect the mRNA and protein expressions of ZEB2 in cancer tissues and corresponding adjacent tissues of 67 SCLC patients who received surgical treatment at the Department of Oncology, Fourth Hospital of Hebei Medical University from February 2018 to November 2019. TargetScan was used to predict the potential target gene of miR-9, which was later verified by Dual luciferase reporter gene assay, qPCR and WB methods. CCK-8 method, Flow cytometry and Transwell experiment were used to detect the effect of miR-9 and ZEB2 over-expression on the biological behaviors of NCI-H446 cells, and WB was used to detect the protein expressions of E-cadherin, N-cadherin and Vimentin in cells. NCI-H446 cells overexpressing miR-9 were used to construct SCLC nude mouse xenograft model, and the effect of miR-9 on the growth of xenografts was observed. Results: The mRNA and protein expression levels of ZEB2 in SCLC tissues were significantly higher than those in adjacent tissues (P<0.01). There is a potential binding site on the 3' UTR of ZEB2 to bind with miR-9. Compared with the control group, the mRNA and protein expression levels of ZEB2 in NCI-H446 cells of the miR-9 over-expression group were significantly reduced (P<0.01); the proliferation, migration and invasion abilities of NCI-H446 cells were significantly suppressed (P<0.05 or P<0.01), and the expression of EMT protein was reduced; However, simultaneous over-expression of ZEB2 could reverse above effects. In in vivo experiments, the size and weight of transplanted tumors in the miR-9 over-expression group were significantly lower than those in the control group (P<0.05 or P<0.01). The expression of ZEB2 protein in the tumor tissues of nude mice in the miR-9 overexpression group was significantly lower than that in the control group (P<0.01). Conclusion: miR-9 can inhibit the biological behaviors of SCLC cells and the growth of NCI-H446 transplanted tumors in nude mice by targeting and regulating ZEB2.