细胞周期蛋白Cyclin G1与肿瘤分子靶向治疗诱导多倍体耐药的机制研究

Drug resistance of molecular targeted therapy servers as a great challenge in the present treatment of clinic oncology. Cell cycle protein Cyclin G1 is overexpressed in various types of tumor cells and tissues, associating with drug resistance and tumor progression. Our preliminary data showed that targeted inhibitor can induce high expression of Cyclin G1 and lead to mitotic slippage and polyploidy, which subsequently results in drug resistance. Apoptosis-related proteins involve in the process that Cyclin G1 deregulation induces polyploidy, and associate with targeted therapeutic drug resistance. In order to dig out a strategy to reverse polyploidy drug resistance and improve the therapeutic effects of small molecular targeted drugs, we are determined to explore the correlation between polyploidization and drug resistance caused by small molecular targeted inhibitors, as well as identify the characterization of the resistant polyploidy cells. We will establish a cell model of polyploidy drug resistance by using small molecular inhibitors, and investigate the correlation between Cyclin G1 overexpression and polyploidy drug resistance and clarify the feasibility to reverse the drug resistance by utilizing apoptosis-related proteins. By using an animal model and clinical samples, we are continue to confirm that targeting apoptosis-related proteins can affect Cyclin G1 expression, as well as its relationship with therapeutic effects and prognosis. Our present proposal does not only provide important theoretical basis for improving targeted therapeutic effects, but also provides research information for identifying a novel inhibitor to specifically kill polyploidy cells.

探讨肿瘤细胞对分子靶向药物耐药的机制是当前肿瘤治疗的迫切需要。细胞周期蛋白Cyclin G1在肿瘤细胞及组织中高表达，并与耐药及进展相关。申请人前期发现靶向药物可诱导Cyclin G1表达升高，导致有丝分裂滑移及多倍体产生，由此产生的多倍体是导致靶向耐药的主要原因；而凋亡相关蛋白参与Cyclin G1异常诱导多倍体的过程，并与靶向耐药密切相关。为了找到逆转多倍体耐药、提高小分子靶向药物疗效的策略，本课题将系统地探讨多倍体与靶向药物耐药的关系、鉴定多倍体细胞的耐药特征。通过构建靶向药物诱导多倍体产生的耐药模型，研究Cyclin G1高表达与多倍体耐药的相关性，阐明利用凋亡相关蛋白逆转该耐药的可行性；并在动物模型和临床上验证干预凋亡相关蛋白影响Cyclin G1表达与肿瘤治疗和预后的关系。本课题将为提高靶向药物疗效提供重要的理论基础，为研发特异性杀伤多倍体细胞的小分子抑制剂提供充分的研究信息。

前期研究表明，CyclinG1在多种实体肿瘤中高表达，其通过诱导多倍体形成导致肿瘤细胞对紫杉类药物耐药。然而，关于CyclinG1在小分子靶向抑制剂诱导多倍体形成及耐药中的作用，目前尚不清楚。本项目通过免疫组化及免疫印迹技术检测相关蛋白的表达水平、ATPlite技术检测细胞增殖情况、流式细胞术或DNA片段实验等检测细胞周期和/或凋亡等。本项目研究发现Aurora激酶抑制剂ZM447439在CyclinG1高表达的乳腺癌细胞中可诱导耐药的多倍体形成，干扰CyclinG1可减少而过表达CyclinG1可增加ZM447439诱导的多倍体产生；而另一小分子抑制ABT-263与ZM447439联合作用于CyclinG1高表达的乳腺癌细胞后，可明显抑制ZM447439诱导的多倍体形成，并显著抑制肿瘤细胞的增殖及诱导凋亡的发生，即两药联用有明显的协同的效应。随后的机制研究表明，ZM447439诱导的Mcl-1表达降低及NOXA表达增高是使ABT-263/ZM447439联用有效的关键因子。最后，我们进一步发现，CyclinG1在以紫杉醇为治疗方案的三阴乳腺癌患者中高表达，并与较差的预后相关。综上所述，本课题首先鉴定出CyclinG1是小分子靶向抑制剂ZM447439诱导多倍体形成及耐药的关键因子，而ABT-263/ZM447439两药联用将有望成为CyclinG1高表达的三阴乳腺癌患者的新的有效治疗方案，从而使CyclinG1成为乳腺癌治疗的一个关键靶点。