DNMT1调节的胆固醇合成代谢在巨噬细胞活化和结肠癌腹腔种植转移中的作用及机制研究

Peritoneal carcinomatosis (PC) takes place with high incidence and poor prognosis in the postoperative and recurrent colorectal cancer patients. However, the mechanism is still not elucidated. The present project set up a mouse PC model, in which we demonstrated that visceral fats were major targets of PC. The DNA methylation, cholesterol synthesis and inflammasome pathways were notably altered according to the analysis of RNA sequencing and pathway enrichment. Combining with the intervention of macrophage DNA methylation and cholesterol synthesis pathway in vitro, we presumed that colorectal cancer cells could induce reprogramming of cholesterol metabolism, M2 activation of macrophages, immunosuppression of tumor microenvironment and progression of PC. In the aspects of cells, mouse models and clinical samples, we are to decipher the mechanism of DNMT1-regulated FDPS and LSS expression, uncover the regulatory role of FDPS/LSS in macrophage activation, reveal the regulatory mechanism of DNMT-FDPS/LSS pathway on PC progression and observe the correlation between key molecules and PC. Our study might shed light on the strategies for the management of PC in the patients with colorectal cancer or other cancers.

术后及复发结直肠癌患者中，腹腔种植转移（PC）发生率高，预后差，然而其机制尚不明确。本项目在预实验中建立了结肠癌PC的小鼠模型，发现内脏脂肪是PC的主要靶组织；利用高通量的RNA测序和通路富集，初步发现PC微环境中巨噬细胞（ATM）胆固醇合成、炎性小体信号及DNA甲基化修饰水平显著改变。结合体外巨噬细胞DNA甲基化和胆固醇合成通路的干预实验，我们推测：结肠癌细胞可能诱导ATM发生胆固醇合成代谢重编程，促使ATM发生M2活化，形成肿瘤免疫抑制微环境，最终促进PC的发生发展。我们拟在细胞、小鼠模型及临床样本中，解析巨噬细胞DNMT1对FDPS/LSS的表观调控机制，阐明FDPS/LSS对巨噬细胞活化的调节作用，揭示巨噬细胞DNMT1—FDPS/LSS通路对结肠癌PC发生发展的调控作用及免疫基础，并考察关键分子与结肠癌PC临床参数的相关性，有望为寻找有效的结肠癌PC防治策略提供重要的理论依据。

术后及复发结直肠癌患者中，腹腔种植转移（PC）发生率高，预后差，然而其机制尚不明确。我们原计划在细胞、小鼠模型及临床样本中，解析巨噬细胞DNMT1对FDPS/LSS的表观调控机制，阐明FDPS/LSS对巨噬细胞活化的调节作用，揭示巨噬细胞DNMT1—FDPS/LSS通路对结肠癌PC发生发展的调控作用及免疫基础，并考察关键分子与结肠癌PC临床参数的相关性。在项目实际开展过程中，我们重点解析了DNMT1抑制剂5氮杂胞苷（5Aza）的全新靶点及其对巨噬细胞胆固醇代谢的调节作用；阐明了5Aza对巨噬细胞活化的调控机制；阐明了5Aza对结肠癌PC发生发展的调控作用及免疫基础；揭示关键通路和重要分子与临床PC的关联。在其他项目的联合资助下，我们还对结直肠癌PC还进行了拓展性研究，取得了超额研究成果。这些成果包括：1）揭示了高脂膳食防治结直肠癌腹腔种植转移的效应和具体机制；2）阐明了结直肠癌细胞的溶血磷脂酸代谢重编程及其对免疫微环境的调控作用和具体机制。如上研究成果为基于肿瘤微环境代谢重编程的结直肠癌防治策略探索提供给了理论依据。