SCLC早期发生转移，预后差，恶性度高。研究证实，CTC是肿瘤复发和转移的主要途径。我们的前期研究发现在SCLC细胞系过表达miR-200，转移瘤形成能力明显增强。基因芯片扫描、RT-PCR及western blot检测发现miR-200显著上调PAI-2的表达。提示miR-200可能通过PAI-2信号途径调控SCLC患者CTC的形成，继而促进SCLC复发和转移，但具体的调控机制尚不清楚。因此，本项目拟通过建立裸鼠肺癌移植瘤和转移瘤模型，应用启动子克隆和CTC研究技术等体内外实验方法研究miR-200/PAI-2信号通路在SCLC患者CTC形成中的作用及其分子机制，并结合详细的临床生物学信息探讨miR-200/PAI-2在SCLC预后评估中的标志物作用，为SCLC提供新的预后评估标志物以及转移控制可能的新靶点及机制解释。

Small cell lung cancer (SCLC) is come up early metastasis and poor prognosis and the higher the degree of malignancy. Recent studies indicated that circulating tumor cells (CTC) are the most important ways in tumor recurrence and metastasis. Our previous studies showed upregulation of the miR-200 level enhanced viability of metastasis formation in SCLC. Screened by gene microarray data and verify the results by RT-PCR, western blot and immunohistochemistry. Discovered miR-200 significantly increase the expression of PAI-2. Suggesting that miR-200 may regulate SCLC patients CTC by PAI-2 signaling pathway form, and then promote SCLC relapse and metastasis, but the specific regulatory mechanism is unclear. Therefore, the project intends to establish the xenograft and metastasis tumor model of lung SCLC in nude mouse, application promoter cloning and CTC research technology in vivo and in vitro experimental methods to detect the role and molecular mechanisms of miR-200/PAI-2 signaling pathway in SCLC patients CTC formation, combined with detailed clinical information to explore the effect of biological markers with miR-200/PAI-2 in prognosis of lung cancer, to provide a new prognostic markers and a potential new target of metastatic control and mechanism of interpretation.