SARI基因通过调控巨噬细胞的募集在结肠“炎-癌”演进过程中的作用及机制研究

Chronic inflammation is strongly corrected with colon cancer, liver cancer, pancreatic cancer intiation. Therefore, it has an important scientific significance to study the functions of important genes. SARI (suppressor of AP-1, regulated by IFN) is a nuclear transcription factor and takes an important role in tumor cell proliferation, apoptosis and angiogenesis. Under the auspices of the National Natural Science Foundation, we have demonstrated that SARI is a novel angiogenesis inhibitor in colon cancer (Dai L, et al. Nature Communications. 2016). Further studies in SARI knockout mice revealed that SARI deletion promoted colitis-associated colon cancer, but did not promote non- colitis-associated colon cancer formation. But the mechanism was still unclear and has not been reported in the literature. Therefore, in this project, chemo-induced colitis and colitis-associated colon cancer are established in SARI gene knockout mice to investigate the effects of SARI on colon tumorgenesis. Furthermore, mouse colonoscopy observation, in vivo macrophage deleting, in vivo immune reconstruction, antibody array, pathology, signal pathway research, clinical sample were performed to determine the mechanism under SARI regulating colon cancer formation. Our study would provide solid evidence for understanding the effects and mechanism of SARI during colitis-associated colon cancer formation and provide a potential target for colon cancer therapy and diagnosis.

慢性炎症是诱发结肠癌、肝癌、胰腺癌等炎症相关肿瘤的重要因素。因此，研究“炎-癌”过程中调控炎症反应的关键基因的功能有重要意义。SARI基因是一个重要的转录因子，调控肿瘤细胞增殖、凋亡及血管生成等。在国家自然基金资助下，我们发现SARI是一个新的肿瘤血管生成抑制因子（Dai L, et al. Nature Communications.2016）在SARI基因敲除小鼠体内进一步研究发现SARI缺失促进肠炎介导的结肠癌发生，但并不促进非炎症介导的结肠癌发生，而作用机制不清楚，也未见文献报导。因此，本课题将利用SARI基因敲除小鼠建立化学诱发的结肠炎和结肠“炎-癌”模型，利用小鼠肠镜活体观察、巨噬细胞体内敲除、体内免疫重建、蛋白芯片检测、病理学检测、信号通路研究、临床样品研究等，对SARI 调控结肠炎及在“炎-癌”过程中的作用机制进行深入研究，将为结肠癌的诊疗提供实验基础和候选的分子标记物。

经过课题组成员4年的研究，我们已经完成了该课题的研究目标和任务，对SARI基因在结肠炎和结肠炎相关结肠癌发生中的作用和分子机理进行了深入研究，取得了原创性的研究成果。该课题的主要研究成果发表在Mucosal Immunology（IF=7.313）和Journal of Cellular and Molecular Medicine（IF=5.310）杂志上，本课题申请人为以上两篇论文的通讯作者，所发表论文均标注本课题基金号：81772939。依托本课题，培养了博士后1名，博士研究生2名，硕士研究生2名。.在本课题基金的资助下，我们综合利用小鼠结肠炎和结肠“炎-癌”演进模型、SARI基因敲除小鼠、MCP-1受体（CCR2）敲除小鼠、巨噬细胞清除小鼠、小动物肠镜活体观察技术、抗体芯片检测技术、基因芯片检测技术、Co-IP与质谱鉴定技术、免疫荧光技术等，同时结合人结肠癌、癌旁及远端结肠组织检测技术，对SARI 基因在结肠炎和结肠“炎-癌”演进过程中的作用和调控机制进行深入研究。我们发现：1）SARI基因缺失促进急性肠炎、慢性肠炎和结肠炎相关结肠癌的发生、发展，但对非肠炎依赖的原发性结肠癌发生无显著调控作用；2）在炎症环境下，SARI基因缺失促进结肠组织内巨噬细胞的募集，敲除巨噬细胞能阻断SARI基因对肠炎的调控作用；3）免疫细胞中SARI基因的缺失对肠炎和肠炎相关肠癌的发生、发展无显著调控作用；4）在炎症环境下，SARI基因缺失促进结肠组织中MCP-1蛋白的表达，抑制MCP-1蛋白表达或敲除CCR2都能有效阻断SARI基因对肠炎和肠炎相关肠癌发生、发展的调控作用；5）在结肠上皮细胞和结肠癌细胞中，SARI蛋白能通过直接与STAT1蛋白结合促进其发生蛋白酶依赖的降解，进而抑制STAT1介导的MCP-1转录。以上研究表明SARI能通过直接作用STAT1，抑制MCP-1的转录和表达，进而抑制炎症环境下巨噬细胞的募集及肠炎和肠炎相关肠癌的发生、发展。这提示SARI基因是一个潜在的肠炎和肠炎相关肠癌的治疗靶点。