CircRNA4779/miR-126/miR-762轴调控胃癌干细胞免疫微环境促进胃癌转移的作用和机制

Gastric cancer metastasis seriously affects the quality of life and prognosis of patients.Circular RNA ( circRNA ) is a new type of RNA that plays critical roles in multiple biological processes discovered in recent years. However, there is still lack of investigation about the role of circRNA in gastric cancer metastasis. Our results showed that circRNA4779 exhibited significant upregulation accompanied with the downregulation of miR-762 in gastric cancer cell line inhibited the expression of miR-126 by lenti-anti-miR-126 transfection . The specific mechanism of its role of circRNA4779 in gastric cancer metastasis still needs further exploration. Previous studies revealed that interferon regulating factor 7 (IRF7) played important role in the regulation of tumor associated macrophage M1/M2 polarization. Thus, we hypothesized that circRNA4779 may regulate gastric cancer stem cell immune microenvironment through miR-126/miR-762/IRF7 pathway to affect gastric cancer metastasis. To verify this hypothesis, we used gastric cancer cell lines, nude mice, and clinical gastric cancer tissue to investigate the function of circRNA4779 in gastric cancer metastasis by using real-time PCR, ELISA, and flow cytometry. This study explored the mechanism of gastric cancer metastasis from the aspect of circRNA4779, which may supply new thought for the treatment and prevention of gastric cancer.

胃癌的转移严重影响患者的预后。环状RNA（circRNA）与胃癌转移的关系仍知之甚少。前期高通量实验结果提示circRNA4779在miR-126敲降表达的胃癌细胞中显著升高，与下调的miR-762一并处于circRNA-miRNA网络调控的核心位置。干扰素调控因子7（IRF7）可调控肿瘤相关巨噬细胞（TAM）的极化。预实验证实miR-762可靶向负调控IRF7。我们合理推测胃癌中存在一条circRNA4779/miR-126/miR-762调控轴，即：CircRNA4779可能吸附下调miR-126的表达而促进miR-762的表达，后者通过靶向负调控IFR7的表达促进TAM的M2极化增加，最终促进胃癌的转移。本项目拟从细胞、组织及动物整体水平探讨circRNA4779在胃癌免疫微环境及转移中的重要作用，明确circRNA4779介导miR-126/miR-762通路对胃癌转移的调控机制。

胃癌在全球范围尤其是亚洲国家长期是高发的肿瘤,大多数胃癌患者一经发现就处于中晚期，胃癌的转移严重影响患者的生存质量及预后，目前尚缺乏高效的靶向治疗手段。circRNA是近年来新发现的一类特殊的RNA，其在多种生物学过程中均发挥着重要的作用。迄今对circRNA的功能及其与胃癌转移的关系仍知之甚少。我们的高通量预实验结果提示circRNA4779（亦称circ0007360）在miR-126敲降表达的胃癌SGC-7901细胞中出现显著变化，其与miR-762一并处于网络调控的核心位置。为此，我们提出假说：circRNA4779可能通过miR-126-miR-762通路调控胃癌干细胞免疫微环境，继而影响胃癌转移的发生。我们通过胃癌细胞、裸鼠荷瘤模型及胃癌临床样本，从分子、细胞、组织以及动物整体水平等多方面探讨circRNA4779在胃癌转移中的重要作用及调控机制。通过研究发现，胃癌组织中circRNA4779、miR-126和IRF7的表达水平明显下调（P＜0.01），miR-762明显上调（P＜0.05）。胃癌中circRNA4779的表达水平与miR-126及miR-762呈负相关（P＜0.01），与IRF7的表达水平呈正相关（P＜0.01）。circRNA4779的表达与胃癌的淋巴转移及肿瘤的分期密切相关（P＜0.01）。circRNA4779的表达水平与胃癌干细胞标志物CD90（P＜0.01）及肿瘤相关巨噬细胞标志物CD206的表达呈负相关（P＜0.05）。体外胃癌细胞实验证实，circRNA4779可经miR-762调控IRF7的表达抑制胃癌的生长。进一步裸鼠移植瘤实验证实了circRNA4779/miR-762/IRF7信号通路可影响胃癌的生长和“干性”获得。本研究从circRNA4779这个新视点揭示胃癌转移的发生机制奠定基础，为胃癌及其并发症的防治提供新的思路。