肥大细胞参与Lgr5+结肠癌干细胞干性维持的研究

Colon cancer are originated from Colon Cancer Stem Cells (CCSC), and Mast Cells (MCs) is one of the main components in the inflammatory microenvironment of colon cancer. During the previous study modeled on mouse colon cancer, the applicants have confirmed the malignant proliferation of Lgr5+ CCSC and the abnormal activation in the Wnt Signaling pathway. What also has been identified are the activation and increased proportion of infiltrated MCs as well as the expression of Lgr5 ligand (R-spondin 1).Despite these findings, it has not yet been tapped whether MCs has a direct effect on the stemness of CCSC. The project intends to build an animal model of inflammation-associated colon cancer in MCs deficient mice. We plan to explore the impact of MCs defects upon the self-renewal, differentiation, tumorigenicity, and the activation of Wnt signaling pathway of CCSC. Also we attempt to examine the R-spondin 1 expression of MCs and its role in maintaining CCSC Wnt signaling pathway in activated condition. The study aims to verify the functional pathyway of MCs - R- spondin 1 - Wnt signaling - CCSC - cancer in the inflammation-related tumor microenvironment, which is responsible for maintaining the stemness of CCSC, thereby eventually leading to the initiative and progress of colon cancer. Thus, this research can cast light on the malignant transformation of non-resolving inflammation in cancer.

结肠癌干细胞（CCSC）是结肠癌的细胞起源，肥大细胞（MCs）是结肠癌炎性微环境的主要细胞成分之一。申请者前期在小鼠结肠癌模型上，确证了Lgr5+ CCSC的恶性增殖及其Wnt通路的异常活化；同时发现浸润的活化MCs比例增加并表达Lgr5配体（R-spondin 1），但MCs是否对CCSC及其干性维持具有直接作用目前尚未阐明。为此，本项目拟研究：1.在MCs缺陷型小鼠的炎性相关结肠癌动物模型中，MCs缺陷对CCSC自我更新、分化、移植成瘤和Wnt通路活化等功能的影响；2.MCs的R-spondin 1表达及其对维持CCSC Wnt通路持续激活的作用。该项目旨在通过证明"肥大细胞- R-spondin 1- Wnt通路 -癌干细胞-癌症"这条功能轴在炎性肿瘤微环境中的有效存在，并介导CCSC的干性维持，从而支撑结肠癌的发生、发展，由此为探讨失控性炎症的恶性转化提供方向。

根据最新文献报道，结直肠癌在全世界2018年新发肿瘤病例数1,096,601，，死亡人数551,269，在所有肿瘤中位列第四，对患者的生命健康产生严重威胁，对政府的医疗保障投入产生了较重的负担，给患癌家庭带来了极大的痛苦。而关于相关的结直肠癌发生发展的基础研究方向主要围绕在肿瘤干细胞、肠道微生物，原癌基因异常激活、肿瘤微环境、肿瘤免疫逃逸等领域。在本基金的支持下，本课题组发现了1.肿瘤干细胞分泌的SCF信号招募活化的肥大细胞，在局部结直肠癌微环境中以RSPO-1 作为介导，肥大细胞持续活化Wnt/β-catenin 信号通道，维持结肠癌干细胞的干性，促进结直肠癌的发生与发展。 2.miRNA-101/CtBP2 通路调控KLRG1基因在记忆性T细胞上的表达，从而影响了记忆性T细胞的抗肿瘤效应，为记忆性T细胞的肿瘤免疫功能的调控提出了新的理论。3.有氧糖酵解是肿瘤细胞发生发展过程中重要的代谢机制，IL-22分子通过作用于己糖激酶-2促进结肠癌细胞的有氧糖酵解，在结肠恶性肿瘤进展过程中发挥重要的作用。以上2、3的发现均发表在SCI收录的高影响因子国际期刊上，以此为基础，我们对于结直肠癌的发生发展从肿瘤微环境、肿瘤代谢，免疫逃逸、原癌基因激活等方面提出了若干新的理论解释，并为后续的临床肿瘤免疫治疗方式的发展提供了理论支持。