整合素αvβ6内吞转运ERK2调控结肠癌细胞核转录因子Ets-1活化及效应的机制研究

Our comprehensive research confirmed that αvβ6 is a key subtype of integrin promoting malignant process of colon cancer during the last 2 decades. Our recent study has showed that: (1) αvβ6 is under rapid internalization and recyling between cell membrane and plasm,which is closely related with ERK2 activation and transport into the nuclear; (2) Analysis of downstream nuclear transcription factors of ERK2 with transcription factor assay shows that αvβ6 can significantly enhance Ets-1 activation; (3) Furthermore, Ets-1 can regulate some malignant gene expression by recognizing sequence GGA(A/T) of promoter. Interestingly, we demonstrated 4 sites containing GGAA sequence in β6 promoter . According to these findings, it may be speculated that: ERK2 can be phosphorylated and transported into the nuclear by β6 integrin inducing Ets-1 activation and downstream biological effects subsequently; moreover, actived Ets-1 can enhance β6 expression by binding its promoter. This process forms a positive feedback mechanism, contributing to the malignant development of colon cancer. Cellular and animal experiments will be processed in this project. A series of advanced technologies will be undertaken, such as siRNA interference, plasmid transfection, fusion protein building, internalization assay, import assay, luciferase reporter gene analysis, ChIP and so on. This program will target at the molecular mechanism of activation and directional transport of ERK2 mediated by β6 trafficking, the influence of this process on the Ets-1 activation and its downstream biological effect, and the positive feedback mechanism of Ets-1 on transcription and expression of β6 integrin. Thus this study will provide theoretic evidence for the novel therapy of colon cancer targeted at integrin αvβ6 and related proteins.

我们近20年系统深入的研究证实αvβ6是促进结肠癌恶性进展的关键整合素亚型。我们最新研究发现：αvβ6在胞膜与胞质之间进行快速内吞胞吐循环，该过程与ERK2活化及转运入核密切相关；分析ERK2下游核转录因子发现αvβ6可显著增强Ets-1活化；同时在β6启动子中也发现4个包含GGAA序列的Ets-1结合位点。我们认为，αvβ6内吞介导ERK2活化及转运入核，促进Ets-1活化并调控下游靶基因的表达及效应；活化的Ets-1特异识别结合β6的启动子，增强β6转录表达，形成正反馈机制，促进结肠癌持续恶性进展。本研究拟通过多层次实验，利用融合蛋白构建、内吞、入核实验、ChIP等关键技术，揭示αvβ6内吞介导ERK2活化、转运入核的分子机制，明确该过程对Ets-1活化及其效应的影响，探索Ets-1正反馈调控β6转录表达的机制，为以αvβ6及其相关蛋白为靶点对结肠癌进行靶向治疗提供重要的理论依据。

我们近20年系统深入的研究证实αvβ6是促进结肠癌恶性进展的关键整合素亚型。我们最新研究发现：αvβ6在胞膜与胞质之间进行快速内吞胞吐循环，该过程与ERK2活化及转运入核密切相关；分析ERK2下游核转录因子发现αvβ6可显著增强Ets-1活化；同时在β6启动子中也发现4个包含GGAA序列的Ets-1结合位点。我们认为，αvβ6内吞介导ERK2活化及转运入核，促进Ets-1活化并调控下游靶基因的表达及效应；活化的Ets-1特异识别结合β6 的启动子，增强β6转录表达，形成正反馈机制，促进结肠癌持续恶性进展。本研究通过多层次实验，利用融合蛋白构建、内吞、入核实验、ChIP等关键技术，揭示αvβ6内吞介导ERK2活化、转运入核的分子机制，明确该过程对Ets-1活化及其效应的影响，探索Ets-1正反馈调控β6转录表达的机制。通过本研究我们发现αvβ6通过活化ERK2-Ets-1信号通路而促进结肠癌的侵袭转移、化疗耐药及定向转移等。更为重要的是，团队结合研究成果制备了αvβ6靶向药物载体，通过体外及体内实验证实了αvβ6靶向药物载体对结肠癌细胞恶性生物学行为的抑制作用，为以αvβ6及其相关蛋白为靶点对结肠癌进行靶向治疗提供重要的理论依据。