Rab21通过促进非磷酸化EGFR内吞诱导自噬参与NSCLC 对EGFR-TKI耐药的机制研究

NSCLC has a high mortality rate. EGFR-TKI could be applied to the treatment of NSCLC but leads to resistance eventually. Induction of autophagy, which participates in cell survival, has been proved to be involved in the EGFR-TKI resistance. We previously demonstrated that oncogenic Rab21 could trigger autophagy. It has been proved that Rab21 mediates the internalization of dephosphorylated EGFR. A recent study found that degradation product of internalized EGFR could induce autophagy through LAPTM4B/Rubicon/ Beclin 1 dependent pathway. Therefore, in the present study, we propose that the dephosphorylation of EGFR by treatment with EGFR-TKI could lead to EGFR internalization through Rab21 dependent manner, resulting in autophagy activation, cell survival and EGFR-TKI resistance. By using EGFR-TKI-resistant cells we developed previously, we will verify the underlying mechanism involved in the “Rab21→EGFR internalization→autophagy” cell signaling transduction and the Rab21 mediated EGFR-TKI resistance. Our study will not only establish a new paradigm that significantly affects our views on mechanisms involved in EGFR-TKI resistance, but will also lay groundwork for developing new therapeutic strategies against EGFR-TKI-resistant NSCLC.

非小细胞肺癌（NSCLC）病死率高，EGFR-TKI用于NSCLC治疗，终将出现耐药。研究显示自噬作为细胞的一种生存机制，参与了EGFR-TKI的耐药过程。申请人在前期研究中发现，促癌基因Rab21能够激活自噬。有研究证实Rab21能够介导非磷酸化EGFR的内吞。最近有研究发现，EGFR内吞后的降解产物可通过LAPTM4B/Rubicon/ Beclin 1通路诱导自噬。基于上述研究我们推测，当EGFR磷酸化被EGFR-TKI抑制后，Rab21介导EGFR内吞，进而诱导自噬，促进细胞生存，产生耐药。本项目将应用前期研究中建立的EGFR-TKI耐药细胞株，研究“Rab21→EGFR内吞→自噬”的信号转导机制，探讨Rab21介导NSCLC EGFR-TKI耐药的过程。本研究有助于揭示EGFR-TKI耐药新机制，并有望为NSCLC EGFR-TKI耐药的治疗找到新的靶点。

表皮生长因子受体（EGFR）是一类具有酪氨酸激酶活性的膜受体，它在肺癌的增殖、分化、迁移等过程中起重要作用。Rab21作为一类通过招募特异效应分子控制囊泡识别转运的小G蛋白能够参与EGFR内吞。本课题通过Oncomine、TCGA、GEPIA数据库分析肺癌组织、癌旁组织中Rab21的表达，证实Rab21在肺癌组织中表达量明显高于癌旁组织，并与预后呈负相关。本课题组通过筛选肺癌细胞系，采用rhRNA敲减技术、慢病毒系统技术，构建敲减、过表达细胞系；在体内、外验证Rab21对肺癌细胞生长、迁移的影响。进一步采用基因芯片，经生物信息学分析筛选参与Rab21表达相关的差异基因，采用GO、pathway、PPI分析，初步寻求参与Rab21表达的靶基因、mircoRNA及相关信号通路。综上所述，本研究为探讨Rab21调节细胞内相关分子内吞促进肺癌细胞的生长奠定了基础。