多种人类肿瘤带有ALK激酶的基因异常，而针对ALK的靶向药物在临床上出现的耐药性突变一直没有有效的药物。本课题组前期通过高通量细胞筛选，发现了Trametinib能够有效地克服由ALK激酶突变引起的耐药性,具有重要的临床意义。初步数据显示，Trametinib很有可能通过除MEK之外的一个未知靶点来实现对细胞增殖的抑制，并且CDK激酶抑制剂p27可能起到了重要的作用。本项目拟通过对信号通路，凋亡和细胞周期等角度检测Trametinib对细胞产生的影响，解析其诱导p27蛋白水平增高的机制。利用表达谱芯片结合诱导耐药细胞突变测序的分析手段，寻找并确定Trametinib的未知作用靶点，阐明该靶点被Trametinib打击后抑制细胞增殖的机制。本项目不仅将为Trametinib在临床ALK耐药性肿瘤上的潜在应用打下坚实的理论和实验基础，并且将为其他更多激酶耐药性突变的新药研发提供新的思路和方向。

Genetic abnormalities in ALK gene are common seen in many types of human cancers, targeted therapy against ALK quickly develops resistant mutations, which are no longer sensitive to most current therapy approaches. By a high-throughput screening of all commercially available therapeutic drugs, our group discovered that a MEK inhibitor, Trametinib，can potently overcome the drug resistance conferred by mutations in ALK gene， which is of great therapeutic significance. Primary data suggest that, Trametinib might target an unknown gene other than MEK to achieve its anti-proliferative effects, in which p27, a CDK inhibitor, might also be closely involved. In this proposal, we are going to explore the cellular effects of Trametinib in signaling transduction, apoptosis, and cell cycle progression, and pinpoint the step where Trametinib induces p27 protein accumulation, at either transcription, translation, or protein degradation levels. Also, with the aids of gene expression array analysis and mutation analysis in induced drug-resistant cell lines, combining the results from other experiments, we will search and verify the unknown target of Trametinib, and disclose the detailed mechanism of how Trametinib overcomes the drug resistance. In addition to providing solid experimental data support for extending the use of Trametinib to novel therapeutic approach against ALK-based drug resistant mutations, this proposal will also inspire novel drug targeting methods and directions to overcome acquired drug resistant mutations in other kinases.