基于毒性通路的大气细颗粒物暴露致肺癌机制研究

Exposure to atmospheric PM2.5 significantly increased the risk of human lung cancer development. This study aims to identify the toxicity pathway and key targets associated with lung cancer development through exposure to the particulate matter and main components. Moreover, we will construct a framework for adverse outcome pathway (AOP), and elaborate the biological dose-response relationship and predict the cancer risk. According to different pollution pattern, five typical regions including Beijing, Shanghai, Guangzhou, Chongqing, and Shenyang, and control city Zhuhai will be recruited. We will collect the atmospheric PM2.5 in these regions in summer and winter season, respectively and followed by analysis of characterization and major toxic components and structure-activity by QSAR modules. Transgenic mice and human bronchial epithelial (HBE) cell transformation assay will be applied to assess whether PM2.5 and main components possessing carcinogenic potential and explore the related mechanisms of chemical carcinogenesis. With a model with co-cultured macrophage and human epithelial cells, together with high-throughput technology, we attempt to identify the “Toxicity Pathway” and “Initiative Molecular Event” underlying PM2.5-associated carcinogenesis. The epigenetic mechanism will be highlighted. Furthermore, internal exposure and effective biomarkers for PM2.5 will be measured in volunteers from recruited cities mentioned above. Panel study will be conducted to evaluate the window of biological effects and verify the stability of the biomarkers. Finally, the approach of systems biology will be applied to integrate the information and data from exposure, biological effects, and human actual exposure, and establish the predictions models for AOP. This effort will lead to identification of the effective biological monitoring markers and strategy of exposure risk assessment for air pollution prevention.

大气细颗粒物PM2.5暴露显著增高肺癌发病风险。本研究旨在识别PM2.5及内载组分诱发肺癌发生的毒性通路和关键靶点，构建有害结局路径AOP框架，阐述剂量反应关系并预测暴露致癌风险。根据不同地区的污染模式，分别在夏/冬季采集5个典型区域城市北京、上海、广州、重庆、沈阳和1个对照城市珠海的PM2.5，解析表征主要内载组分并进行构效关系分析。应用转基因动物诱癌和细胞转化试验检测PM2.5及组分的致癌活性并探讨致癌机制。利用巨噬细胞和上皮细胞共培养模型，结合高通量组学技术筛查与PM2.5致癌相关的“毒性通路”或“关键事件”，重点探讨表观遗传网络调控机制。选择暴露区域的人群，进行内暴露和标记物检测；并用panel study评价不同生物学效应的窗口期及标志物的稳定性。应用系统生物学方法整合暴露、生物学效应和人群实际暴露的数据，建立AOP框架，为大气污染防控提供有效的生物监测指标和暴露风险评价手段。

大气细颗粒物(PM2.5)暴露可以显著增加肺癌的发病风险，而目前缺乏有效方法评价PM2.5的致癌风险。本项目从动物，体外细胞和人群流行病学不同层面对PM2.5进行研究，构建了一系列动物和体外细胞的PM2.5毒性评价模型，阐明了PM2.5内载组分诱发肺癌发生的毒性通路和关键靶点，明确了剂量反应关系并预测暴露致癌风险，为评价PM2.5对机体的致癌效应。本项目已经完成了既定的研究任务，主要成果包括以下几个方面：1. 构建了大气细颗粒物实时染毒装置。利用该装置阐述了大气颗粒物对小鼠多脏器损伤的时间效应关系和可恢复性，明确了炎症反应在机体多脏器损伤中的重要作用；发现机体不同代谢模式可以影响大气颗粒物对小鼠的脏器损伤，其中限制饮食对肺部炎症和损伤有保护作用，而高脂饮食则加重这种损伤；利用PP2A的Aα基因在髓系细胞条件性敲除的小鼠发现Aα基因缺失可以显著增强PM2.5对小鼠的肺部炎症，说明PP2A调控通路可能在PM2.5引发小鼠肺脏损伤中起重要作用；2. 建立了基于细胞生物学效应的PM2.5毒性风险评估模型，包括短期毒性效应评价模型和长期致肺癌的评价模型，并应用该模型结合基准剂量模型（BMD）分析对来自3个城市不同季节的PM2.5的多种毒性终点效应进行了评价，发现PM2.5短期暴露引起的遗传毒性和氧化损伤与颗粒物有机组分密切相关，而炎症反应与无机组分相关。PM2.5的致癌效应与其多环芳烃组分水平呈显著相关。3. 利用人群流行病学分析了PM2.5暴露与人群疾病的关系，发现PM2.5暴露与人群血脂、血压、心血管疾病患病率，代谢综合征发生率，儿童哮喘，以及肺功能下降等密切相关，同时对PM2.5中重要组分多环芳烃类（PAHs）对机体致癌的表观遗传调控机制重点研究，发现了FLT1和TRIM36基因甲基化，组蛋白H3ser10磷酸化H3K27和H3K36三重甲基化等表观遗传标志，有望应用于PM2.5暴露的健康监测。