ELMO3在结直肠癌侵袭转移中的作用及调控机制

Colorectal cancer is one of the most malignant tumors in the world. Metastasis is the main reason for the high mortality of colorectal cancer patients. Therefore, it is critical to explore the molecular mechanism of invasion and metastasis of colorectal cancer, which is helpful to establish a new target for preventing and treating colorectal cancer. Currently, Engulfment and Cell Mobility (ELMO) protein family plays an important role in tumor cell chemotaxis and metastasis. However the expression of ELMO3 is lack in many cancers. We found that the expression level of ELMO3 in colorectal cancer tissues with lymph node metastasis was significantly higher than that in colorectal cancer tissues without lymph node metastasis, and presented a opposite trend compared with its upstream target microRNA-647 (miR-647). Moreover, silencing ELMO3 significantly down-regulated the invasion and metastasis of HCT116 cell. The current results suggest that the axis of miR-647-ELMO3 contributes to invasion and metastasis of colorectal cancer. In the present project, we will explore the regulatory role and targets of ELMO3 in invasion and metastasis and the relationship between ELMO3 and the development, prognosis of colorectal cancer through changing the expression of ELMO3, the human metastasis array and histopathological technique. Furthermore, we will classify the upstream miR-647 regulating ELMO3 through constructing luciferase reporter vectors and dual luciferase activity report. Finally, we will isolate and identify the interacting proteins of ELMO3 with tandem affinity purification coupled to mass spectrometry (TAP/MS). The target signaling network of ELMO3 will also be confirmed. This study will ultimately validate the role and regulatory mechanism of ELMO3 in invasion and metastasis of colorectal cancer and provide basic data and proof for exploring the treatment of colorectal cancer with ELMO3.

侵袭转移是导致结直肠癌患者高死亡率的主要原因。我们前期发现ELMO3蛋白在有淋巴结转移的结直肠癌组织中高表达，提示ELMO3可能在侵袭转移中扮演重要角色，但相关调控机制并不明确。预试验中ELMO3潜在的上游调控分子miR-647和ELMO3呈相反的表达趋势及siRNA敲降ELMO3显著下调了结肠癌HCT116细胞的侵袭和转移能力，提示miR-647-ELMO3轴线可能是调控结直肠癌侵袭转移的重要信号途径。为进一步明确ELMO3的功能和调控机制，本项目拟结合免疫组化、基因沉默、PCR Array、荧光素酶报告基因检测系统、串联亲和层析耦联质谱技术以明确ELMO3在结直肠癌侵袭转移中的作用和功能、上游调控分子及机制、下游相互作用蛋白和信号调控通路。该研究将揭示ELMO3在结直肠癌侵袭转移中的角色、信号调控机制，为进一步探索针对ELMO3的结直肠癌治疗药物提供新线索和理论依据。

结直肠癌是人类最常见的恶性肿瘤之一，全世界每年结直肠癌的发病人数仅次于肺癌和乳腺癌，位居所有肿瘤的第三位。侵袭转移是影响患者治疗效果并导致死亡率居高不下的最重要原因之一，揭示结直肠癌侵袭转移的发生发展分子机制、确立防治靶点并积极探索有效的抗复发、转移的治疗手段，对进一步提高结直肠癌患者的治愈率和生存率具有重要意义和现实的迫切性。目前发现ELMO家族可通过形成蛋白复合物影响肿瘤细胞的运动、侵袭和转移能力，但是家族成员ELMO3在结直肠癌中的功能、作用和调控机制尚未清楚。本项目在前期研究的基础上，通过转录组测序及分析、调控miR-647的表达并结合荧光素酶报告基因检测系统，明确了miR-647通过靶向ELMO3-Hippo信号途径调控结直肠癌细胞的增殖、侵袭和转移；通过APEX2及质谱技术鉴定出和ELMO3相互作用的Dock家族等蛋白，筛选出与结直肠癌侵袭转移相关的分子，并检测改变其表达水平对肿瘤侵袭转移能力的影响。本项目的实施一方面揭示了ELMO3调控结直肠癌侵袭转移的作用机制，另一方面对结直肠癌转移的预后监测提供理论依据和新线索，并为探索针对ELMO3的结直肠癌治疗药物提供基础资料，为基因治疗方法在结直肠癌中的应用提供新思路。