IMP3调控上皮间质转化和肿瘤干细胞进而参与结肠癌发生和转移的机制研究

The epithelial-mesenchymal transition (EMT) plays a critical role during the process of invasion and metastasis in colon cancer. EMT could promote the acquisition of stem-like properties in cancer cells and cancer stem cell (CSC) has EMT properties, both of which are closely linked. However, the underlying mechanism of the interaction between EMT and CSC still remain unclear. We previously found Insulin-like growth factor-II (IGF-II) mRNA binding protein 3 (IMP3) is critical for EMT mediated metastasis of colon cancer. IMP3 could maintain the stem cell property and serve as a potential stem marker, possibly through the transactivation of Wnt/β-catenin signalling. Here we proposed that IMP3 may serve as a key modulator of signalling cross talk between EMT and CSC, which is responsible for the tumorigenesis and metastasis of colon cancer through the interplay between EMT and CSC. In this study, we aim to elucidate the mechanism of IMP3 involved in colon cancer tumorigenesis and metastasis through transactivation of colon CSC with EMT property, which is helpful to identify critical marker and therapeutic target.

上皮间质转化（EMT）在肿瘤侵袭转移过程中发挥重要作用。EMT可促进肿瘤细胞获得肿瘤干细胞（CSC）干性，而CSC具有EMT样特征，两者关系密切，但目前对两者相互作用机制仍不清楚。我们前期发现胰岛素样生长因子II mRNA 结合蛋白3（IMP3）是EMT关键调控分子之一，介导EMT参与结肠癌转移；IMP3可维持结肠癌CSC干性； IMP3可能通过活化Wnt/β-catenin通路参与CSC调控，是潜在的CSC干性调控基因。据此我们提出IMP3可能是结肠癌EMT与CSC信号串话（cross talk）的关键节点之一，通过介导Wnt/β-catenin通路调控结肠癌EMT和CSC的内在转化，进而参与结肠癌发生和转移过程。本课题拟通过体内外实验，初步阐明IMP3介导EMT样结肠癌CSC形成和干性维持，进而参与结肠癌发生和转移的机制，最终为结肠癌提供关键的分子标记和干预靶点。

背景：RNA结合蛋白IMP3在结肠癌中高表达，但是具体的功能机制并不清楚。.研究方法：通过国际公用结肠癌数据和复旦大学附属肿瘤医院的样本分析IMP3的临床表达情况及其意义。通过CCK8,EdU增殖实验，克隆形成实验，划痕实验和transwell小室实验来研究IMP3在结肠癌细胞系中的功能。通过RNA-seq、RIP-seq、RNA免疫共沉淀和荧光素酶报告基因实验来揭示IMP3的下游作用机制。通过体内裸鼠成瘤实验来进一步验证IMP3对结肠癌细胞系成瘤及转移能力的影响。.研究结果：与癌旁组织相比，IMP3在结肠癌肿瘤组织中显著高表达。体内外实验表明IMP3能够促进结肠癌细胞的增殖，侵袭和迁移能力。IMP3能够直接结合在MEKK1的3’-UTR区域，并影响MEKK1 RNA的稳定性，进而激活MEK/ERK通路活性。功能回复实验表明MEKK1/MEK/ERK通路直接介导了IMP3对结肠癌的生物学功能。高表达IMP3的结肠癌病人的总体生存时间和无病生存时间显著降低，联合分析IMP3和MEKK1的表达，发现同时高表达IMP3和MEKK1的病人预后较差。.结论：我们的研究结果表明IMP3通过激活MEKK1/MEK/ERK信号通路的活性促进结肠癌的进展和转移，IMP3/MEKK1/MEK/ERK信号轴可能做为潜在的治疗和药物作用靶点。.