caspase-9在重离子辐射诱导的丝裂灾变致死效应中的作用研究

丝裂灾变（MC）是发生在凋亡或坏死前的肿瘤抑制机制。MC致死效应机制中联系有丝分裂异常与细胞死亡的分子纽带尚未阐明。本课题组前期研究显示，重离子诱导肿瘤细胞发生MC的同时，线粒体凋亡通路的关键起始蛋白酶caspase-9被活化。因此推测caspase-9活化是联系重离子诱导的MC与凋亡的重要环节。为证实该假说，研究caspase-9功能对理解MC与凋亡的衔接机制将有很大裨益。p53是细胞在DNA 损伤后诱导凋亡的关键因子。本项目拟以不同p53状态肿瘤细胞为研究对象，采用siRNA技术和人重组真核表达载体，明确细胞p53状态对重离子诱导MC致死效应中凋亡通路的影响；并利用siRNA技术、caspase-9抑制剂及定点突变法，明确caspase-9在重离子诱导的MC和凋亡间的纽带作用。本研究是对重离子诱导肿瘤细胞MC致死效应的有益探索，为进一步提高重离子治疗疗效奠定理论基础。

Mitotic catastrophe(MC) is an oncosuppressive cascade that precedes cell death and senescence. The molecular bridges that link mitotic aberrations and cell death in lethal mechanism of MC are still largely elusive. Caspase-9 is the key initiator caspase in mitochondria apoptosis pathway. The preliminary studies of our research group discovered that caspase-9 was activated after irradiation high LET carbon ion on metaphase HeLa cells, when MC was effectively induced. We proposed that activation of caspase-9 is an critical link that contacts MC with apoptosis. To confirm this assumption, the study of caspase-9 function will contribute to the understanding of cohesive mechanism between MC and apoptosis. p53 is the key molecular of apoptosis induction in the case of DNA damages. In this application project, taking tumor cells with different p53 status as research object, siRNA technique and recombinant of eukaryotic expression vector for human p53 will be used to confirm whether p53 status in tumor cells influrences the apoptotic pathway following MC induced by heavy ions. And siRNA technique, specific inhibitor of caspase-9 and site-directed mutagenesis technique will be used to exploit the function as link of caspase-9 in connection between MC and lethal apoptosis induced by heavy ions. This study will contribute to understanding the lethal effects of MC induced by heavy ions and establishing foundations for promoting cancer curative effects of heavy ions.