lncRNA XIST 通过miR-32-5p/EZH2 分子轴调控结直肠癌HCT-8细胞的恶性生物学行为

目的：探讨lncRNA XIST 通过miR-32-5p/果蝇Zeste 基因增强子同源物2（enhancer of zeste homolog 2，EZH2）分子轴调控结直肠癌HCT-8 细胞的恶性生物学行为。方法：收集2014 年7 月至2018 年8 月中南大学湘雅医院直肠肛门外科资料完整的结直肠癌患者28 例癌组织和配对的癌旁组织标本，采用qPCR检测结直肠癌组织及细胞系中lncRNA XIST 和miR-32-5p 的表达水平，双荧光素酶报告基因验证lncRNA XIST、miR-32-5p 和EZH2 的靶向关系，并进一步通过WB检测EZH2 的表达水平。CCK-8、Transwell 及Annexin V-FITC/PI 染色流式细胞术检测HCT-8 细胞增殖、迁移及凋亡情况。结果：lncRNA XIST 在结直肠癌组织及细胞系中高表达，且在HCT-8 细胞中表达最高（P<0.05 或P<0.01）。双荧光素酶报告基因证实，lncRNA XIST 靶向负调控miR-32-5p（P<0.05），且EZH2 是miR-32-5p 的靶基因。敲降lncRNA XIST 抑制HCT-8 细胞增殖和迁移并诱导其凋亡（P<0.05或P<0.01）；进一步实验证明，敲降lncRNA XIST 上调miR-32-5p 的表达水平，从而下调EZH2 表达水平，进而抑制HCT-8 细胞增殖和迁移并诱导其凋亡。结论：lncRNA XIST通过miR-32-5p/EZH2 分子轴促进HCT-8 细胞增殖、迁移并抑制细胞凋亡。

lncRNA XIST regulates the malignant biological behaviors of colorectal cancer HCT-8 cells through miR-32-5p/EZH2 molecular axis

Objective: To explore the mechanism of lncRNA XIST (XIST) regulating the biological behaviors of colorectal cancer HCT-8 cells via miR-32-5p/EZH2 (enhancer of Zeste homolog 2) axis. Methods: A total of 28 pairs of cancer tissues and corresponding para-cancerous tissues form colorectal cancer patients with complete clinical data were collected from the Colorectal and Anal Surgery,Xiangya Hospital of Central South University during July 2014 and August 2018. The expression levels of lncRNA XIST and miR-32-5p in colorectal cancer tissues and cell lines were detected by qPCR. The targeted relationship between lncRNA XIST, miR-32-5p and EZH2 was verified by dual luciferase reporter gene, and the expression level of EZH2 was further detected by WB. The proliferation,migration and apoptosis of HCT-8 cells were detected by CCK-8, Transwell and flow cytometry with Annexin V-FITC/PI staining, respectively.Results: lncRNA XIST was highly expressed in colorectal cancer tissues and cell lines with the highest expression in HCT-8 cells (P<0.05 or P<0.01). Dual luciferase reporter gene assay validated that lncRNA XIST negatively regulated miR-32-5p (P<0.05),and EZH2 was a target gene of miR-32-5p. Knockdown of lncRNA XIST inhibited proliferation and migration and induced apoptosis of HCT-8 cells (P<0.05 or P<0.01). Further experiments demonstrated that knockdown of lncRNA XIST up-regulated the expression of miR-32-5p and further down-regulated the expression level of EZH2, thereby inhibiting the proliferation and migration of HCT-8 cells and inducing apoptosis. Conclusion: lncRNA XIST promotes proliferation, migration and inhibits apoptosis of HCT-8 cells via miR-32-5p/EZH2 axis.