抑癌基因NDRG2调控Keap1/Nrf2信号通路的分子机制及其功能研究

The homestasis and regulation of reactive oxygen species (ROS) is very important for the maintainance of cellular structure and function. Studies have shown that Keap1-Nrf2 signaling pathway is the key regulator of cellular ROS level. Low ROS level is vital for the survival and self-renewal of cancer stem cells. Therefore, it's of great significance to clarify the regulation mechanism of Keap1-Nrf2 signaling pathway for eradication of cancer stem cells. Our lab found a new tumor suppressor gene NDRG2 with reduced expression in colorectal cancer tissues, which was a new colorectal cancer prognosis biomarker. Our recent studies showed that NDRG2 could increase the protein stability of Keap1, inhibit the expression of Nrf2, improve the intracellular ROS level, and inhibit the survival of colorectal cancer stem cells. Based on this preliminary data, in current project, we will analyze the detailed molecular mechanism of NDRG2 regulating Keap1-Nrf2 signaling pathway. Also we will clarify how NDRG2 regulating ROS and the effect on mitochondria function, genome structure stability and malignant behavior of colorectal cancer stem cells. Finally, we will further use intestinal tissue specific ndrg2 knockout mice and clinical samples for in vivo study and clinical correlation analysis respectively. Our study will elucidate the mechanism of how NDRG2 regulating Keap1-Nrf2 signaling pathway and its clinical significance.

反应活性氧（ROS）的稳态平衡和调控对于细胞的结构功能维持至关重要。研究表明，Keap1/Nrf2信号通路是调控细胞ROS水平的枢纽。低水平的ROS对于肿瘤干细胞的存活和自我更新至关重要。因此，阐明Keap1/Nrf2信号通路的调控机制对于清除肿瘤干细胞具有重要意义。课题组发现的新抑癌基因NDRG2在结直肠癌组织中表达降低，是一新的结直肠癌预后标记分子。我们的近期研究显示，NDRG2可增加Keap1的蛋白稳定性，抑制Nrf2的表达，提高细胞内ROS水平，并抑制结直肠肿瘤干细胞的存活。基于此，本课题将系统分析NDRG2调控Keap1/Nrf2信号通路的分子机制，阐明NDRG2调控ROS对结直肠癌细胞线粒体结构功能、基因组结构稳定性及其对肿瘤干细胞恶性行为的影响。并进一步利用ndrg2 knockout小鼠进行动物在体功能和临床关联分析，明确NDRG2调控Keap1/Nrf2信号通路的临床意义

项目基本完成既定研究目标。发现NDRG2可以通过增强Keap1/Nrf2复合体的形成，降低Nrf2的表达，导致ROS水平增加，增加结直肠癌细胞的5-FU化疗敏感性。进一步利用免疫缺陷小鼠荷瘤模型和PDX模型，明确了NDRG2促进5-FU化疗敏感性的动物在体功能。同时，我们还分析了NDRG2促进细胞分化的细胞机制。发现NDRG2可以通过抑制泛素连接酶Skp2的表达，进而增加p21和p27的蛋白稳定性，增加p21和p27的表达。最终促进细胞周期阻滞和细胞分化过程。.项目执行过程中，发表SCI论文4篇、获得国家发明专利授权1项。课题组先后 6人次参加了国内肿瘤领域的专业学术会议。课题负责人张健获得陕西省杰出青年基金（2018）；培养科研骨干2名、研究生3名。.