EGFR靶向抑制剂耐药新机制：GRHL2介导上皮-间质转化和抑制EGFR再循环

获得性耐药是表皮生长因子受体靶向抑制剂(EGFR-TKI）治疗失败的主要原因。EGFR相关分子突变/扩增等虽能部分解释其耐药，但仍有30-40%耐药机制不明。我们通过前期研究筛选到Difi和HCC4006的吉非替尼耐药细胞株，并发现：1）转录因子粒状头样2（GRHL2）是一个新的EGFR-TKI耐药关键基因；2）耐药细胞株由上皮向间质表型转化（EMT）和细胞表面EGFR分子减少。基于E-cadherin和Rab25启动子均具有GRHL2结合位点，我们提出假设：GRHL2表达下调后通过双重调节-促进EMT激活EGFR下游信号，下调Rab25抑制EGFR再循环通路,进而介导了对吉非替尼的耐药。本课题拟利用基因转染、染色质免疫共沉淀、免疫荧光等方法，从分子、细胞、动物模型和临床样本四个层面验证上述假设，旨在阐明GRHL2介导EGFR-TKI耐药的分子机制，为临床EGFR靶向治疗提供新的干预靶点。

Acquired resistance is the main reason for failure of epidermal growth factor receptor inhibitors (EGFR-TKI) treatment. Mutations or amplification of EGFR and its downstream signal transduction could partially explain their resistance, but the resistance mechanisms of 30-40% patients is still unclear. In our previous study, we obtained gefitinib-resistant cell lines derived from Difi and HCC4006 cells, and found that: (1) transcription factor grainy head-like 2 (GRHL2) is a new key gene responsible for EGFR-TKI resistance; (2) we also found that the gefitinib-resistant cells occured epithelial - mesenchymal transition (EMT) and the EGFR molecular in cell surface decreased. We then hypothesize that: GRHL2 mediated gifitinib resistance by double regulation: activating EGFR downstream signaling pathway by promoting EMT and inhibiting EGFR recycling pathway by down-regulating the expression of Rab25. This project intends to use gene transfection, chromatin immunoprecipitation, FACS and other methods，from the molecular, cellular, animal models and clinical samples to verify our hypothesis. Our present study will clarify the role of GRHL2 played in EGFR-TKI resistance, and thus provides a new target and the theoretical basis for clinical EGFR-TKI targeted therapy and drug development.