EphA2通过Wnt/β-catenin信号通路调控胃癌奥沙利铂耐药细胞EMT的发生从而影响其耐药机制研究

Epithelial-mesenchymal transition (EMT) is not only an key event in the tumor invasion and metastasis, but also closely related with tumor cell drug resistance. Our previous study found that: up-regulation of EphA2 expression included gastric carcinoma cell EMT and reduced cell sensitivity to oxaliplatin. In the meantime, oxaliplatin-resistant human gastric carcinoma cell strains were established gradually by increasing dose of oxaliplatin and acquired mesenchymal phenotype. This project plans to use oxaliplatin-resistant human gastric carcinoma cell strains as an in vitro model and nude mouse xenograft of peritoneal implantation as an in vivo model. Firstly, the silencing of EphA2 expression in oxaliplatin-resistant gastric carcinoma cells can reverse the EMT occur and affect its sensitivity of oxaliplatin.Furthermore, we will investigate EphA2 regulates oxaliplatin-resistant gastric carcinoma cell EMT which affects its oxaliplatin sensitivity through Wnt/β-catenin signaling pathway. This study will first clarify the relationship between gastric carcinoma cell EMT and drug resistance, and look for theoretical basis on reversing drug resistance of gastric carcinoma.

上皮-间质转化（EMT）不但是诱发肿瘤浸润转移的早期关键事件，而且与肿瘤细胞的耐药密切相关。我们的前期研究发现：EphA2过表达的胃癌细胞发生EMT，且对奥沙利铂的敏感性降低；通过药物浓度递增间歇诱导法建立的人胃癌奥沙利铂耐药细胞株获得间质样表型。本项目拟用人胃癌奥沙利铂耐药细胞为体外模型和裸鼠腹腔种植瘤为体内模型，首先研究沉默EphA2在胃癌奥沙利铂耐药细胞中表达能否逆转其EMT发生并影响奥沙利铂敏感性，接着通过回复β-catenin在EphA2稳定沉默的胃癌奥沙利铂耐药细胞中表达，探讨EphA2是否通过Wnt/β-catenin信号通路调控胃癌奥沙利铂耐药细胞EMT的发生从而影响其对奥沙利铂敏感性。本研究将首次探讨胃癌细胞EMT与耐药之间关系，望为临床治疗逆转胃癌耐药提供理论依据。

项目背景.上皮-间质转化(EMT)不但是诱发肿瘤浸润转移的早期关键事件，而且与肿瘤细胞的耐药密切相关。EphA2 在胃癌细胞EMT 发生过程中发挥作用，但是EphA2 在胃癌细胞耐药中作用及其具体作用机制尚不明确。.主要研究内容.用人胃癌奥沙利铂耐药细胞SGC-7901/LOHP作为体外模型和裸鼠皮下种植瘤作为体内模型，首先研究沉默EphA2 在SGC-7901/LOP表达逆转其EMT 发生并影响奥沙利铂敏感性，接着应用LiCl激活稳定沉默EphA2 的SGC-7901/LOP细胞Wnt/β-catenin 信号通路，探讨EphA2 通的过Wnt/β-catenin 信号通路调控SGC-7901/LOP细胞EMT 的发生从而影响其对奥沙利铂敏感性。.主要结果.1. 与胃癌SGC-7901细胞比较， SGC-7901/L-OHP细胞中EphA2高表达，对奥沙利铂耐药性加强；.2. 沉默EphA2能明显抑制胃癌SGC-7901/L-OHP细胞中EphA2的表达，对奥沙利铂耐药性下降，同时能下调间质性标志物N-cadherin和转录因子Snail的表达，上调上皮性标志物E-cadherin的表达；.3. 沉默EphA2能明显下调胃癌SGC-7901/L-OHP细胞中Wnt/β-catenin 通路标志物β-cateni、cyclinD1、c-myc和TCF-4的表达;.4. 当加入Wnt/β-catenin 通路激动剂LiCl后，能明显促进SGC-7901/L-OHP细胞EMT，激活Wnt/β-catenin 通路，促进Wnt/β-catenin 通路标志物β-catenin、cyclinD1、c-myc和TCF-4的表达，而沉默EphA2可以逆转LiCl的影响，提高细胞对奥沙利铂的敏感性;.5.通过裸鼠皮下种植瘤作为体内模型，进一步验证了EphA2通过Wnt/β-catenin 通路调控胃癌奥沙利铂耐药细胞EMT及对奥沙利铂的敏感性。.科学意义.EphA2可以通过Wnt/β-catenin通路调控胃癌奥沙利铂耐药细胞EMT 发生从而影响细胞对奥沙利铂敏感性，进一步证实肿瘤细胞EMT 发生与化疗药物的耐药性密切相关。