基于乏营养环境下Nrf2促进非小细胞肺癌侵袭转移的机制研究

Reactive oxygen species (ROS) accumulation can cause cellular injury under the nutrient starvation environment. However, non-small cell lung cancer even grow quickly and occur invasion and metastasis under high ROS levels. The mechanism is still unknown. Studies have shown that NF-E2 related factor 2 (Nrf2), the key transcription factor of anti-oxidative stress system, can inhibit the intracellular ROS levels effectively, and be against cell damage. Our previous researches showed that the level of Nrf2 was correlated with lymph node metastasis and distant metastasis positively. Moreover, the expression of Nrf2 was positively related with the expression of Epithelial-Mesenchymal Transition (EMT)-relative markers and CXCR4 in NSCLC tissues. We speculate that ROS accumulation can induce Nrf2 high-expression abnormally, and Nrf2 can promote the invasion and metastasis of NSCLC by activation of the SDF-1/CXCR4 signaling pathway. This research regulates the expression of Nrf2 through lenti-viral transfection, and simulates oxygen stress state of tumor microenvironment in vitro. In addition, fluorescence imaging system in vivo and immunohistochemistry are used to observe tumor occurrence and development trends in orthotopic transplantation and metastatic model of nude mice. At last, we explore the role and mechanism of Nrf2 in the invasion and metastasis of NSCLC under the nutrient starvation environment from the level of histology, cytology and molecular biology, and provide new evidence for the prevention and control of the malignant progression of NSCLC.

乏营养环境下活性氧（ROS）堆积可致细胞损伤。而高ROS条件下非小细胞肺癌（NSCLC）仍生长迅速并发生侵袭转移，其机制尚未明确。抗氧化应激关键转录因子NF-E2相关因子2（Nrf2）可负向调控ROS水平，对抗细胞损伤；我们前期研究发现，Nrf2表达与NSCLC患者淋巴结浸润及远处转移密切相关，且Nrf2与上皮-间质转化（EMT）相关标志物及趋化因子受体CXCR4在NSCLC组织中的表达呈正相关。由此推测：乏营养环境下ROS积累可诱导Nrf2异常高表达，其对抗细胞损伤的同时激活SDF-1/CXCR4通路，促进NSCLC侵袭转移。本研究拟通过慢病毒转染双向调节Nrf2的表达，体外模拟肿瘤乏营养环境，建立裸鼠原位及转移瘤模型，采用小动物活体成像和免疫组化等方法，从组织、细胞和分子水平探究Nrf2在肿瘤乏营养微环境下促进NSCLC侵袭转移行为的调控机制，为NSCLC恶性进展的防治提供新思路。

本课题通过前期研究筛选适宜干预条件，在体外试验中成功模拟实体肿瘤的乏营养环境；同时通过小动物活体成像系统准确预测合理时间点对干预裸鼠进行剖杀及检测，联合不同检测方法论证本研究首次提出的假说：作为抗氧化应激关键转录因子，在乏营养环境下Nrf2亦可激活侵袭转移相关通路SDF-1/CXCR4，调节多种侵袭转移相关蛋白的表达，从而促进非小细胞肺癌侵袭转移行为。本研究从宏观角度出发，将肿瘤组织视为“社会群体”，与其所处的内外环境全面结合进行了研究，多层次探讨了氧化应激-抗氧化应激体系对肿瘤组织整体进化中的作用。