ETV4通过LOXL2激活结直肠癌ERK通路的分子机制和临床意义研究

In our previous proteomics and transcriptomics study, we identified ETV4，a key transcription factor, as a potential candidate biomarker in colorectal cancer (CRC). We previously found that ETV4 was markedly up-regulated in CRC compared with normal control, and was positively correlated with lymph node metastasis and poor prognosis of CRC patients. We further demonstrated that ETV4 could promote epithelial-mesenchymal transition (EMT), proliferation, migration and invasion of CRC cells in vitro. RNA-seq analysis and molecular mechanism study revealed that LOXL2 was required for ETV4-induced EMT, ERK signaling activation and target gene expression such as NID1. In addition, we also found that ETV4 could induce DNA demethylation of NID1, and directly interact with LOXL2. Based on these findings, we proposed that ETV4 interacting with LOXL2 could synergistically promote targeted gene expression such as NID1 by regulating DNA methylation and transcription, which will lead to proliferation and metastasis of CRC through activating ERK signaling pathway. In this project, we will focus on clarifying the molecular mechanisms underlying the regulatory role of ETV4 and LOXL2 in CRC metastasis, as well as evaluating their diagnostic and therapeutic value in CRC clinical management. This project will verify our scientific hypothesis, increase our understanding of tumor biology, and pave the road for precision medicine in CRC diagnosis and treatment.

我们前期筛选发现转录因子ETV4是一个重要的候选结直肠癌致癌基因。进一步预实验发现：ETV4在结直肠癌中高表达，与病人淋巴结转移和预后密切相关；其过表达可促进结直肠癌细胞增殖、迁移侵袭、EMT和ERK通路激活。RNA-seq等实验初步证实：LOXL2是一个新的ETV4靶基因，且LOXL2对ETV4介导的EMT、ERK通路激活和下游靶基因表达是必须的。预实验还揭示ETV4与LOXL2存在相互作用，ETV4还可促进NID1等下游靶基因启动子的去甲基化。我们由此提出学术假说：ETV4直接促进LOXL2转录，两者相互作用，并进一步促进NID1等下游靶基因的启动子去甲基化和转录上调，从而激活ERK通路促进结直肠癌细胞增殖转移。本项目拟在此基础上，对ETV4与LOXL2交互调控结直肠癌细胞增殖转移的分子机制及临床靶向诊疗意义进行深入研究，证实我们的学术假说，为结直肠癌的精准诊断和治疗提供实验依据。

在本项目中我们发现ETV4在结直肠癌组织中显著高表达，并且与淋巴结转移、肿瘤分级分期和病人预后显著相关，是一个潜在的结直肠癌预后生物标志物。生物功能上我们发现ETV4在细胞和动物水平上都可以促进结直肠癌细胞的增殖、EMT转变和转移。机制上ETV4可以通过转录激活LOXL2的表达来介导结直肠癌细胞的恶性转变。ETV4可以募集LOXL2到NID1启动子区域来介导NID1的去甲基化和转录表达进而激活FAK/ERK信号通路，最后促进结直肠癌细胞增殖、EMT转变和转移。此外我们也发现在临床组织样本上ETV4、LOXL2、NID1的表达显著正相关且与NID1启动子甲基化水平显著负相关，ETV4和LOXL2组合在一起作为预后因子对结直肠癌病人的预测更加有效。总的说来，在本项目中，我们发现ETV4在结直肠癌转移过程中发挥着重要作用，并揭示了ETV4/LOXL2/NID1这样一个新的信号轴在结直肠癌发展中的生物学功能和分子机制。