EGFR-TKI是EGFR突变的晚期非小细胞肺癌(NSCLC)的一线治疗药物，但常因T790M突变产生继发耐药，其机制尚不明确。根据以往研究，我们推测NSCLC在TKI治疗前就存在少量包含T790M突变且Wnt通路活化的干细胞克隆，治疗后耐药的干细胞逐步获得生存优势，最终形成耐药细胞群。本课题拟以NSCLC细胞系为对象，确定T790M突变克隆是否具干细胞特性，随后通过分析T790M突变细胞含量、Wnt通路活性等因素对TKI耐药时间及程度的影响，探讨肺癌干细胞中Wnt通路活性在T790M突变导致的TKI耐药中的作用机制，探讨Wnt抑制剂逆转耐药的可能性。研究结果有助于阐明T790M继发性耐药机理，探讨抑制Wnt通路克服T790M继发性耐药的可能性，具有重要的理论价值和潜在的应用前景。

EGFR-TKI is the first-line therapy of advanced non small cell lung cancer (NSCLC) patients with EGFR mutation. However, the secondary resistance happens frequently due to T790M mutations, and the mechanism of secondary resistance is not very clear. According to the previous studies, we hypothesized that there are small amount of cancer stem cells with T790M mutation, Wnt pathway activation in the tumor tissue of NSCLC patients before EGFR-TKI treatment, after treatment of TKI resistant stem cells gradually gain a survival advantage, eventually forms resistant cell population against TKIs. We are going to study the characteristics of the T790M mutantion to figure out whether it is stem cells or not by studying the NSCLC cell lines and to further explore the role of Wnt pathway in the self-renewal of stem cells and drug resistance; Then we will study the effects of T790M mutantion and its Wnt pathway activities in NSCLC cells on the drug resistance against TKIs, so as to explore the mechanism of drug resistance in lung cancer stem cells with T790M mutation; We will also to investigate the Possibility of Wnt inhibitors to reverse the sensitivity of T790M mutant NSCLC cells to EGFR-TKIs drugs and explore the possibility to reverse the resistance of EGFR-TKIs. The results help to clarify the mechanism of T790M secondary resistance and provide a new strategy to overcome T790M mediated secondary resistance by inhibitor of Wnt antagonist genes, which is of significance for both theoretical study and clinical tumor therapy.

EGFR-TKI是EGFR突变晚期非小细胞肺癌(NSCLC)的一线治疗药物，T790M突变是继发耐药的常见原因，其机制尚不明确。本课题以EGFR-TKI敏感性、耐药型和继发耐药型3种细胞为研究对象，实验未能发现T790M突变与干细胞特性的关联性，基本明确了T790M突变细胞H1975中Wnt信号通路活化可以导致抗凋亡蛋白表达，是EGPR-TKI耐药的重要因素。）采用脱甲基化策略，通过诱导Wnt拮抗基因表达，可抑制Wnt信号，降低抗凋亡蛋白的表达水平，增加继发性耐药细胞对ECFR-TKI药物的敏感性，有可能成为克服T790M突变导致的耐药的策略。基本上达到本课题预定的目标。