MiR-100失活在重金属污染物砷协同激活突变Ptpn11促发肺癌中的关键作用及机制

Lung cancer has become a serious health problem in human because its incidence and mortality rates continue to rise among all malignancies, however, the underlying molecular mechanisms remain unclear. Currently, it is believed that the synergistic effects between environmental and genetic factors contribute to lung carcinogenesis. Thus, it is very important to identify the oncogenic molecular bases commonly for both environmental and genetic factors, in which microRNA (MiR) has drawn much attention. In our previous studies, we found a significant decrease of MiR-100 expression in malignant transformed mouse fibroblast (MEFs) and lung tumor tissue with gain-of-function (GOF) mutation of Ptpn11 under arsenic (As) induction. Furthermore, down regulated MiR-100 expression was found in human lung epithelia Beas-2B (B2B) cells with GOF Ptpn11 over expression stimulated by As and in lung cancer cells. Additionally, down-regulation of MiR-100 expression significantly promoted the malignant transformation of MEFs and increased the proliferation potential of B2B cells. Our preliminary results indicate that dysregulated MiR-100 expression may play an important role in lung carcinogenesis induced by both environmental and genetic factors. In this application, we plan to test our central hypothesis by using recently established MiR-100 conditional knock-out and mutant Ptpn11 knock-in mouse models in combination with multi-disciplinary molecular/cellular biology research tools, with objectives to investigate the impact of MiR-100 down-regulation on lung epithelial cell transformation and murine lung tumorigenesis induced by Ptpn11 genetic mutation and As treatment, and to elucidate the underlying molecular mechanisms. We expect that the results from this study will provide new clues for the prevention and treatment of the deadly disease of lung cancer.

肺癌因发生率和死亡率持续上升而严重危害人类健康，且机制不清。目前多认为与环境及遗传因素的协同作用有关，寻找其共同分子基础意义重大，其中微小RNA（MiR）是被关注的热点之一。我们前期用重金属环境污染物砷诱导Ptpn11激活突变细胞模型，建立了MiR差异表达谱，发现As在诱导Ptpn11突变小鼠细胞恶性转化、裸鼠成瘤及小鼠肺癌的发生过程中,伴有MiR-100表达的显著下降：进一步发现其在肺癌细胞或As诱导的Ptpn11激活突变的人肺上皮B2B细胞中也表达降低；下调MiR-100明显促进小鼠细胞恶性转化及B2B细胞的增殖潜能，提示MiR-100可能是环境及遗传因素协同促发肺癌的关键分子之一。本课题拟用已建立的MiR-100条件性敲除小鼠及细胞模型，结合临床样本，研究MiR-100表达的下降对遗传及环境因素诱导的肺上皮细胞恶性转化及鼠肺肿瘤发生的影响，并阐明其机制，从而为肺癌的防治提供新线索。

肿瘤包括肺癌的发生发展机制问题一直是本领域的研究热点和难点之一，本组认为遗传修饰后的细胞在环境因素诱导下更容易恶性转化可能是肿瘤高发与早发的关键环节之一，寻找其关键分子机制意义重大。本组首先用重金属环境污染物砷（As）诱导Ptpn11（SHP-2）激活突变细胞模型，建立了miR差异表达谱，发现As在诱导SHP-2激活突变小鼠细胞恶性转化、裸鼠成瘤及小鼠肺癌的发生过程中,伴有miR -100表达的显著下降：进一步发现其在肺癌细胞或As诱导的SHP-2激活突变的人肺上皮B2B细胞中也表达降低；下调miR-100明显促进小鼠细胞恶性转化及B2B细胞的增殖潜能，由此提出miR-100可能是环境及遗传因素协同促发肺癌的关键分子之一的科学假设并获得立项，用已建立的miR-100条件性敲除小鼠及细胞模型，结合临床样本进行深入研究。发现miR-100失活、SHP-2激活突变的人、小鼠MEFs、B2B细胞在环境因素As、老化的纳米材料暴露下更容易恶性转化和成瘤，SHP-2激活突变的间充质干细胞在体外可以自发恶性转化，其机制可能与EMT、线粒体代谢紊乱有关；miR-100与激活突变SHP-2有显著的协同作用，miR-100可能靶向FZD-8、CDC25A、BMPR2等影响肺癌、胃癌恶性生物学行为，SHP-2激活突变可能因为MAPK途径异常活化，促进了老化纳米材料诱导的细胞恶性转化，SHP-2表达水平可能通过CXCL-8参与维持EGFR T790M突变肺腺癌干性及靶向药物耐药性。miR-100肺特异性敲除小鼠已经建立，但未发现自发肺肿瘤，目前正在用环境因素诱导正在进行中。该课题初步验证了miR-100协同激活突变SHP-2参与肺癌发生的科学假说，基于该项目目前已经发表英文期刊文章9篇，中文期刊文章5篇，硕士生论文6篇，博士论文5篇，国际会议摘要1篇，培养硕士6人，博士5人。