NE诱导TDG/NEIL1的DNA修复失衡调控结直肠癌发生发展的分子机制

Psychological stress hormones and tumor occurrence and progression are closely related, but its mechanism has not yet elucidated. Our previous work and data from TCGA database showed that psychological stress could promote the growth of colorectal cancer and NE level was significantly increased, accompanied by TDG’supregulation and NEIL1’sdownregulation, the latter two express balance disorders to increase the mutation. TDG participates in DNA demethylation, NEIL1 participates in BER base repair pathway, suggesting that abnormal expression of both ends of the basement and the base repair balance of BER are broken, the base repair error rate increases, stem cell mutation Increased risk, so that the intestinal stem cells to tumor stem cells, and promote the occurrence of colorectal cancer. In this study, we used in vivo and in vitro experiments to analyze the relationship between the level of NE and the expression of TDG, NEIL1 and the mechanism and regulation of colorectal cancer. The effects of TDG and NEIL1 on the changes of intestinal stem cells and the mechanism of intestinal stem cell tumor were investigated by using two-generation sequencing technique, marker tracking and qRT-PCR to analyze its clinical relevance with colon cancer patients. The aim of the study was to reveal the mechanism of DNA repair imbalance of TDG / NEIL1 induced by NE in the transformation of intestinal stem cells into tumor stem cells and then promote the occurrence of colorectal cancer.

心理应激激素与肿瘤的发生发展密切相关，但其机制尚未阐明。我们前期工作结合TCGA数据库分析表明，心理应激可促使结直肠癌生长且NE水平显著增高，伴有TDG上调而NEIL1下调，后两者表达平衡失调致突变增加。TDG参与DNA主动去甲基化，NEIL1参与BER碱基修复通路，提示两者表达异常致使TDG的碱基切除和BER的碱基修复平衡被打破，使碱基修复错误率增加，干细胞发生突变的几率增大，从而使肠道干细胞向肿瘤干细胞转化，促进结直肠癌的发生。本研究拟采用体内体外实验分析NE的水平改变与TDG、NEIL1等的表达相关性及对结直肠癌的作用和调控机制；利用二代测序技术、标记物追踪、qRT-PCR等探究TDG、NEIL1对肠道干细胞突变影响及肠道干细胞瘤化机制，并分析其与结肠癌患者的临床相关性。研究意义旨在揭示NE诱导TDG/NEIL1的DNA修复失衡在肠道干细胞向肿瘤干细胞转化继而促结直肠癌发生的机制。

结直肠癌是全球第三大常见男性癌症，第二大常见女性癌症。我国结直肠癌的发病率和死亡率也逐年上升，带来了巨大的健康负担和经济负担。申请者前期工作中发现，心理应激可促使结肠癌进展且去甲肾上腺素（NE）水平显著增高，伴有TDG上调而NEIL1下调。课题在临床样本、细胞水平以及动物水平等不同层次解析了NE对结肠癌进展的影响、TDG对基因突变的影响及TDG-DNMT3A-TIMP2轴对结肠癌细胞生物效应的影响，以及NEIL1影响结肠癌细胞增殖的机制研究。NE调控癌细胞生长和肿瘤血管生成、促进结肠癌的进展，去甲肾上腺素转运体（NET）参与调控结肠癌细胞的迁移、侵袭能力；在结肠癌组织中TDG高表达，NEIL1低表达，两者呈负相关，且过表达TDG可使基因组突变数目增加，抑制结肠癌细胞增殖、促进细胞凋亡（SW480出现抑制细胞凋亡的趋势）、抑制细胞的迁移侵袭，通过TDG-DNMT3A-TIMP2轴影响结肠癌细胞的迁移和侵袭；miR-7-5p负向调控NEIL1，进而促进结肠癌细胞的增殖、抑制细胞凋亡。项目研究成果将为结直肠癌的迁移侵袭提供新的认识，为结直肠癌靶向药物的开发提供新的思路和策略。课题在执行期间发表论文8篇，培养硕士研究生4人。