miR-24-3p介导的恶性结肠干细胞与巨噬细胞crosstalk 在炎症性结肠癌发生中的作用机制研究

It has been reported that inflammation contributes to 25% tumorigenesis, which attracted much more attention. However, the underlying mechanism of colitis-associated colon cancer (CAC) is unclear. In our study, we performed mice colon cancer model and the data showed that miR-24-3p specifically promoted CAC progression but has no effect on APC+/min mice. Notably, in AOM/DSS-induced CAC, compared with wide-type mice, we identified that the infiltration of macrophages in miR-24 knockout (KO) mice were increased, and the secretion of Ectodysplasin A2 (TNFRSF27-specific ligand) was dramatically elevated in colonic lamina propria lymphocyte (LPL) of miR-24 KO mice, which mimicked inflammatory microenvironment. Using colonic organoid model, we further found that miR-24-3p boosted malignant proliferation of colon stem cell via targeting TNFRSF27/β-catenin/c-Myc. Furthermore, the conditional medium from miR-24-3p KO colonic organoids fostered macrophage chemotaxis and M1 polarization. Herein, we hypothesized that miR-24-3p/TNFRSF27/β-catenin mediates the crosstalk between malignant stem cells and macrophage to specifically promote CAC. Therefore, this project aims to reveal the specific functions and molecular mechanisms of miR-24-3p mediated macrophage polarization in tumor microenvironment modification and colonic stem cells' malignant proliferation by using clinic, animal models, organoid culture and molecular techniques, which will provide a powerful theoretical thesis for the accurate diagnosis and treatment in CAC.

25%的肿瘤发生与炎症相关，而炎性结肠癌（colitis-associated colon cancer，CAC）发生机制仍不清楚。利用基因工程小鼠，我们确认miR-24-3p可特异性促进CAC小鼠肠癌进展，而对非炎性结肠癌发生无影响。确认miR-24-3p主要调控巨噬细胞炎症，微环境类器官模型结果发现miR-24敲除小鼠的结肠巨噬细胞浸润增加、结肠淋巴细胞产生更多的Ectodysplasin A2并模拟干细胞恶性增殖所需的炎症微环境。更重要的是miR-24-3p靶向TNFRSF27/β-catenin/c-Myc促进结肠干细胞恶性增殖；miR-24-3p敲除的结肠类器官上清促进了巨噬细胞趋化和M1极化。因此我们提出科学假设：通过临床、动物、类器官、分子水平阐述miR-24-3p介导的巨噬细胞M1/M2极化在CAC肿瘤微环境改造及干细胞恶性生长中的作用机制，为CAC精准诊疗提供理论依据。

25%的肿瘤发生与炎症相关，而炎性结肠癌（colitis-associated colon cancer，CAC）发生机制仍不清楚。临床缺乏炎症性结肠癌和散发性结肠癌特异的诊断和治疗分子标志物。该项目发现了在炎症性结肠癌和散发性结肠中分别发挥重要作用的microRNA。miR-24-3p在炎性结肠癌组织和血浆样本中高表达且表达水平与结肠癌发展进程呈显著正相关。miR-24敲除抑制炎症性结肠癌的发生发展。结肠干细胞中miR-24-3p通过靶向TNFRSF27促进干细胞的恶性增殖以及增殖相关信号通路，而且结肠干细胞中miR-24-3p影响巨噬细胞极化和趋化能力进而改造肿瘤微环境。miR-708在散发性结肠癌组织和血浆样本中高表达且表达水平与结肠癌发展进程呈显著正相关。miR-708作为Meg3下游靶基因，在散发性结肠癌组织和血浆样本中与Meg3表达水平呈显著负相关。miR-708敲除显著抑制了APCmin/+散发性结肠癌的发生发展。miR-708通过靶向SOCS3促进结肠干细胞的恶性增殖，且Meg3可以抑制miR-708在结肠干细胞增殖和结肠癌发生发展中的促进作用。miR-24-3p和miR-708有望成为结肠癌精准诊断和精准治疗中的分子标志物。