激活突变SHP-2酪氨酸磷酸酶促进重金属污染物诱发的小鼠肿瘤发生及其分子机制探讨

Malignant tumor is most harmful to human. The incidence of most malignant tumor keeps rising and more young people is being implicated. The mechanism of carcinogenesis is much complicated with interact of environmental and genetic factors in multi-steps or multi- processes. So, the exploration of tumorigenic mechanism and tumor related genetic factor finding become one of most hotspots in tumor research. Our previously study supported by Chinese national natural science foundation demonstrated gain-of-function mutant SHP-2 tyrosine phosphatase enhanced malignant behaviors of many kinds of tumor and the more incidence of leukemogenesis or carcinogenesis was found in D61G SHP-2 mutation knock-in mouse treated with DNA damage or induced by heavy metal contamination (such as arsenic). The SHP-2 mutant mouse embryonic fibroblasts (MEFs) with impaired cytokinesis showed more sensitive malignant transformation and abnormal signal activation than wild type MEFs under arsenic induction. These preliminary data suggest that gain-of-function mutant SHP-2 might be involved in carcinogenesis induced by environmental factor. We will use this well-generated mutant SHP-2 knock-in mouse and MEFs model with multi-disciplinary approaches employing laboratory animal science, and molecular/cellular biology research tools to test our hypothesis in this proposal. The results obtained from this project will elucidate the role of mutant SHP-2 in heavy metal-induced carcinogenesis promotion and identify novel targets for mechanism research of tumorigenesis.

恶性肿瘤严重危害人类健康，其发病多数呈上升和年轻化趋势。目前认为恶性肿瘤发生可能是环境及遗传因素共同作用的多环节多途径复杂过程，探索这些因素的致癌机制及发现更多的肿瘤发生相关基因是这一领域的研究热点。我们前期在国家自然科学基金资助项目的研究中发现：激活突变SHP-2酪氨酸磷酸酶促进了多种肿瘤恶性生物学行为，同时发现用DNA损伤性处理或环境因素中重金属污染物（如砷As）处理SHP-2激活突变小鼠，其白血病等肿瘤发病明显增加；SHP-2激活突变的MEF细胞分裂异常，经As处理后更易发生恶性转化及信号分子异常活化；提示SHP-2激活突变可能参与环境因素诱发的肿瘤发生。本课题拟用已建立的SHP-2激活突变基因敲入小鼠及细胞模型，利用本实验稳定的实验动物学、分子生物学及细胞生物学实验手段，研究激活突变SHP-2是否参与重金属环境污染物诱导的白血病等肿瘤发生并探讨其机制，为肿瘤发生机制研究提供新线索。

SHP-2是第一个被定义为癌基因的磷酸酶，激活突变 SHP-2可能参与了环境因素诱发的肿瘤发生。本课题用已建立的激活突变SHP-2基因敲入小鼠、细胞模型进行了系列研究，发现在重金属等环境因素诱导下，激活突变SHP-2 小鼠更容易发生多器官系统肿瘤，含激活突变SHP-2的小鼠MEFs及肺上皮等细胞更容易发生恶性转化及裸鼠成瘤；在环境因素诱导下，激活突变小鼠MEFS细胞出现周期、分裂异常及遗传不稳定性；分子机制研究提示可能与MAPK等异常活化及表观遗传学改变有关，其中表观遗传学改变中，miR100失活可能是激活突变SHP-2及环境污染物诱导肿瘤的共同机制之一，进一步研究发现miR100失活可以诱导细胞恶变，且可能与EMT发生有关，为此，我们专门建立了miR100条件性敲除小鼠模型，研究miR100失活在环境因素诱导下肿瘤发生中的关键作用；同时发现SHP-2或者重金属环境污染物本身对多种肿瘤的恶性生物学行为具有促进作用，这些促进作用可能与其激活突变SHP-2与Gab1等结合增强、MAPK异常活化、 重金属污染物慢性应激诱导的EMT等机制有关。研究结果为肿瘤发生机制探索具有指导价值，同时为SHP-2功能研究具体补充作用。通过本课题研究，发表SCI 论文4篇，待发表2篇；中文期刊论文6篇，国际学术会议摘要2篇，国内会议摘要3篇；研究生大论文8篇，待发毕业研究生论文1篇。国际学会会议报告1次，国家级学术会议大会报告4人次，特邀单位学会报告3人次；建立原创性miR100条件性敲除小鼠模型1个。一名博士等待毕业答辩，8名硕士获得硕士学位。