NRP1募集Miro1的重新定位维持结直肠癌细胞定向迁移的头导极性

Microenvironment interacting with cancer cells might promote directional migration, sustain motile directionality of cancer cells, and improve the efficiency of metastasis. In our previous study, we have found that the colorectal cancer cells changed their migration directionality when the direction of VEGF stimulation has been changed. F-actin concentrated on the leading edge of cancer cells as well. When VEGF linked its receptor, NRP1, Miro1 also aggregated at one end of the cancer cells. These findings indicated that the interaction between NRP1 and Miro1 might participate in maintaining the leading-edge polarity of cancer cells for migration. In this study, we attempt to find out the connecting patterns and the binding sites between NRP1 and Miro1, the transportation mode of intracellular mitochondria relocation, the energetic effects or release of possible molecules after mitochondrial relocation. Next, we try to explore the signal pathway provoked by NRP1 linked to Miro1, and the availability of simulating to interrupt keypoint proteins among NRP1/Miro1 pathway for anti-metastasis. After keypoint proteins expression has been linked to predict prognosis of patients with the colorectal cancer, we are sure that the leading-edge polarity of cancer cells may play a pivotal role on directional migration resulting from NRP1 and Miro1 connections. This study will bring about conceptual findings in the understanding of metastatic mechanism, and provide evidences of targeting methods for treatment of cancer metastasis based on blockage of migrating capacity and disturbance of migrating directionality toward cancer cells.

微环境与肿瘤细胞相互作用，促进肿瘤细胞的定向迁移，维持细胞运动的方向性，提高肿瘤转移的有效性。我们前期研究，发现了结直肠癌细胞在血管内皮生长因子（VEGF）的刺激下，改变迁移方向，癌细胞头导端F-actin聚集，VEGF与其受体NRP1结合，募集Miro1聚集于癌细胞一端，可能维持癌细胞迁移的头导极性。本项目拟明确NRP1与Miro1的结合形式与结合位点，诱发癌细胞内线粒体重新定位的转运方式，阐述线粒体重新定位的能量效应和分子释放机制，解析NRP1、Miro1结合后诱发的信号转运途径，模拟中断NRP1、Miro1信号通路节点蛋白抗转移的有效性，分析节点蛋白表达与结直肠癌患者临床预后的相关性，确定NRP1、Miro1维持癌细胞的头导极性在肿瘤细胞定向迁移的关键作用。项目研究展现肿瘤转移机制的全新理念，为阻断肿瘤细胞迁移能力和干预肿瘤细胞迁移方向的抗转移治疗，提供分子信号靶点和理论依据。

肿瘤转移是结直肠癌患者难以治愈的重要原因。肿瘤微环境与肿瘤细胞的相互作用，促使肿瘤细胞发生定向迁移，但其具体机制尚未清楚。在本研究中我们通过免疫组化染色标记Cdc42，在高分化腺癌组织中，腺腔较规则，癌性腺腔缘表达Cdc42（向心性分布），浸润于间质中的癌细胞、将要浸润于间质的癌细胞一侧表达Cdc42（离心性分布），结合临床随访分析，发现了Cdc42在结直肠癌细胞极性表达与结直肠癌患者预后不良相关，Cdc42呈离心性分布的患者预后差于向心性分布的患者。由此推测，Cdc42的特异性分布可能是导致癌细胞发生定向迁移的原因，从而促进了癌细胞转移。利用细胞趋化方向检测模型，给予VEGF刺激后，细胞内Cdc42的表达量增高，对VEGF的刺激表现出剂量和时间依赖性，而且Cdc42出现在癌细胞前导缘的比例明显增高，因此细胞外VEGF是促使Cdc42出现前导极性表达的重要因子。NRP1作为细胞膜表面VEGF受体，当VEGF与NRP1结合后，促使Cdc42激活并使其重定位至结直肠癌细胞前导缘，从而诱导细胞中侵袭性伪足的形成。在这一过程中，活化的Cdc42促使癌细胞前端细胞内F-actin表达增加并发生重塑，癌细胞发生定向迁移。癌细胞通过VEGF/NRP1轴，激活Cdc42并使其重定位于迁移的结直肠癌细胞前部，极大增强了肿瘤细胞的迁移潜能。本研究由肿瘤细胞发生定向迁移这一现象入手，结合细胞形态改变、细胞骨架重塑和VEGF抑制剂的使用，明确了结直肠癌细胞定向迁移的关键细胞信号分子，为抑制肿瘤转移提供了潜在的治疗策略。