Objective: To analyze the association of Nur77 with overall survival of gastric cancer patients and investigate the role of Nur77 in invasion and migration of gastric cancer cells.
Methods: Oncomine database was used to analyze the expression of Nur77 in gastric cancer and gastric mucosa tissues, and the distribution characteristics of Nur77 protein between gastric cancer and normal tissues were compared using Human Protein Atlas. GEPIA2 was used to analyze the relationship of Nur77 expression and the patients' survival. The expression of Nur77 in gastric cancer cell lines GES-1, AGS and MKN-45 were detected by Western blotting. The regulatory interactions between IL-6 and Nur77 were verified by transfecting the cells with specific Nur-77 siRNA and Nur-77-overexpressing plasmid. The changes in migration ability of the cells following Nur-77 knockdown were assessed with scratch assay. The effect of Nur-77 overexpression or IL-6 knockdown, or their combination, on migration and invasion of the gastric cancer cells were examined using Transwell assay. The effect of Nur77 expression level on NF-κB/IL-6 pathway activation was analyzed using Western blotting.
Results: Oncomine database showed that gastric cancer tissues expressed a significantly higher level of Nur77 mRNA than normal tissues (P < 0.05). Nur77 expression was detected mostly in the nucleus, and a high Nur77 expression was associated with a poor survival outcome of the patients (P < 0.05). In gastric cancer cells, the high expression of Nur77 participated in the regulation of IL-6. Nur77 silencing significantly lowered the migration ability of the cells (P < 0.05), and IL-6 silencing significantly attenuated the enhanced migration caused by Nur77 overexpression (P < 0.05). Nur77 participates in the activation of NF-κB/IL-6 signaling pathway by regulating the expression of p-p65, p65, p-Stat3 and Stat3.
Conclusion: A high Nur77 expression is strongly correlated with a poor prognosis of gastric cancer patients. Nur77 promotes the invasion and migration of gastric cancer cells possibly by regulating the NF-κB/IL-6 signaling pathway.
目的: 探讨孤儿核因子受体（Nur77）在胃癌组织中表达及其与患者预后状况之间联系，研究Nur77在胃癌细胞侵袭与迁移进程中的作用机制。
方法: 利用Oncomine数据库在线分析Nur77在胃癌及胃黏膜组织中mRNA表达情况；基于Human ProteinAtlas网站数据对比胃癌及正常胃组织中Nur77蛋白表达分布特征；GEPIA2在线分析工具评估Nur77与患者总生存期之间联系；蛋白免疫印迹法(Western blot)比较正常胃黏膜上皮细胞GES-1与胃癌细胞AGS、MKN-45中Nur77蛋白表达差异；分别通过siRNA靶向干扰以及质粒转染上调Nur77表达和靶向下调IL-6验证Nur-77与IL-6之间表达调控关系；运用划痕实验检测干扰Nur77表达前后胃癌细胞的迁移能力改变；将胃癌细胞分空载体组和过表达Nur77组以及空载体转染后干扰IL-6处理组，过表达Nur77结合干扰IL-6处理组（质粒转染24 h后siRNA继续处理24 h）经Transwell小室实验检测Nur-77及IL-6在胃癌细胞迁移和侵袭过程中作用；利用Western blot检测Nur77表达对NF-κB/IL-6信号通路活化的影响。
结果: Oncomine数据库在线分析显示，与正常胃黏膜组织相比胃癌组织中Nur77的mRNA表达水平显著升高（P < 0.05）；免疫组化结果显示，胃癌组织中Nur77多表达于胃癌细胞细胞核内；Nur77的高表达与胃癌患者不良预后相关（P < 0.05）；胃癌细胞中高表达的Nur77参与IL-6的表达调控；划痕实验和Transwell小室结果显示，Nur77可能通过IL-6参与胃癌细胞的迁移和侵袭进程（P < 0.05）；Western blot结果显示，Nur77通过调控p-p65、p65、p-Stat3、Stat3的表达参与NF-κB/IL-6信号通路活化。
结论: 胃癌中高表达Nur77与患者不良预后密切相关；Nur77可能通过调控NF-κB/IL-6信号途径活化参与胃癌细胞侵袭与迁移进程。
Keywords: Nur77; gastric cancer; invasion; migration; nuclear factor-κB/interleukin-6.