RBM5基因逆转人肺腺癌EGFR-TKI获得性耐药的分子机制研究

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) is one of the targeted agent with preferable clinical benefit to certain type of non-small cell lung cancer (NSCLC). However, the TKI acquired resistance is the key factor to limit its curative effect,which becomes the focus that scholars pay close attention to. Our previous studys showed that, the expression of RBM5 and EGFR was negatively correlated in lung cancer tissues, and transformation of exogenous RBM5 could down-regulate the expression of β-catenin,which is the key gene of classic Wnt pathway. Studes demonstrated that the application of inhibitors of β-catenin signaling pathway was able to reverse the resistance of TKI. Therefore, we make the following hypothesis: the transformation of exogenous RBM5 in tumor cells could delay or reverse TKI resistance through the inhibition of Wnt signaling pathway.Thus,in this study, we will carry on a further research, with the intervention of RBM5 transformation/knockout and inhibitors of β-catenin signaling pathway, to investigate the regulation between RBM5, EGFR signal pathway, and Wnt/ β-catenin signal pathway and the mechanism of TKI acquired resistance and reversal. And it will provide the scientific basis and targets for the development of non small cell lung cancer targeted therapy clinically.

表皮生长因子酪氨酸激酶抑制剂（EGFR-TKI）对EGFR突变的非小细胞肺癌凸显疗效，而TKI的获得性耐药使其应用陷入瓶颈，故颇受关注。我们前期研究发现：在肺癌组织中RNA结合基序蛋白5（RBM5）与EGFR的表达呈负相关；导入外源性RBM5 可下调β-catenin（Wnt经典通路的关键基因）的表达。也有研究表明EGFR与Wnt/β-catenin 存在交叉通路，且与TKI获得性耐药密切相关。故我们推测：向肺腺癌细胞中导入外源性RBM5可以通过抑制EGFR和Wnt/β-catenin信号通路延缓或逆转TKI耐药。本研究将在人肺癌细胞系、动物移植瘤模型中，联合采用RBM5基因导入、β-catenin通路阻滞剂干预，来明确RBM5与EGFR、Wnt/β-catenin通路之间调控关系，明确TKI获得性耐药发生和逆转的分子机制，为临床非小细胞肺癌靶向治疗的发展提供科学依据。

目的:表皮生长因子受体-酪氨酸激酶抑制剂（EGFR-TKI）可以有效地控制非小细胞肺癌（NSCLC）。然而，EGFR-TKI获得性耐药限制了其在临床的应用。RBM5是假定的肿瘤抑制因子，它可以抑制肺癌Wnt/β-catenin信号通路。本实验意在揭示RBM5在NSCLC中EGFR-TKI获得性耐药中的作用。.方法：人肺腺癌PC9和吉非替尼耐药PC9/AB2细胞系经RBM5 cDNA转染，吉非替尼和选择性Wnt/β-catenin通路抑制剂（ICG-001）治疗后，分别进行体外和体内试验。.结果：PC9/AB2细胞对吉非替尼的抑制浓度比亲本细胞高40倍。PC9/AB2细胞的RBM5水平较低，但核β-连环蛋白和EGFR水平较高。RBM5的过度表达诱导了吉非替尼耐药NSCLC细胞对吉非替尼治疗的敏感性（17.23±2.09 mmol/l，3.76±2.09 mmol/l），并下调了Wnt/β-catenin通路相关蛋白的表达和EGFR磷酸化。此外，RBM5表达诱导肿瘤细胞周期停滞和凋亡，但降低了肿瘤细胞迁移、细胞侵袭和Wnt/β-catenin和EGFR通路的活性。在体外和体内实验中过表达RBM5和选择性Wnt/β-catenin通路抑制剂（ICG-001）对NSCLC的作用具有协同作用。.结论：过表达RBM5通过下调Wnt/β-catenin和EGFR通路活性使NSCLC细胞对EGFR-TKI敏感性增加。需要进一步研究RBM5是否是一种治疗EGFR-TKI获得性耐药的新策略。