小细胞肺癌细胞分泌的膜联蛋白A1调控血脑屏障微环境介导其脑转移的机制研究

Small cell lung cancer (SCLC) is the most aggressive histologic subtype of lung cancer, with a strong predilection for metastasizing early. However, the cellular and molecular basis of SCLC brain metastasis is poorly known. Some recent studies revealed that brain microvasculature was the primary soil for metastatic tumor cell attachment and growth in the brain. We previously found that SCLC cells acted on human brain microvascular endothelial cells (HBMEC) to induce disassembly of TJ that leading to increased endothelial permeability and SCLC cells transendothelial migration. These data suggested that brain microvasculature might play an important role in the SCLC extravasation into the brain parenchyma. Therefore, we compare the gene expression profile of SCLC cell and SCLC cell co-cultured with HBMEC by DNA microarray and Annexin A1 was identified as a significant up-regulated gene. Further results showed that Annexin A1 was associated with SCLC metastasis to the brain. Based on these results, our projects will be focused in the role of Annexin A1 in migration across the blood brain barrier and metastasis to the brain, including Annexin A1 potential clinical relevance, the detailed mechanisms of Annexin A1 in the SCLC metastasis to brain. Finally, we will use the mice model to analyze whether the occurrence of SCLC metastasis to brain is blocked by prevention the effect of Annexin A1. These works are necessary to improve a better understanding of the mechanisms of SCLC brain metastasis and provide a potential therapeutic target for SCLC brain metastasis. More importantly, these studies will provie the strong evidence to verify the theory of the metastasis niche.

小细胞肺癌（SCLC）具有向脑特异性转移的病理特点，具体机制尚不清楚。前期发现，SCLC产生分泌因子改变脑微血管内皮细胞屏障功能，促进其迁移入脑。我们从寻找影响SCLC"脑转移微环境"形成的因子入手，利用肿瘤脑转移动物模型获得SCLC脑转移细胞株，基因芯片比较具有不同脑转移能力的SCLC细胞间差异表达基因，获得候选基因-膜联蛋白A1（Annexin A1），可以被SCLC细胞分泌到细胞外促进细胞间粘附。本项目拟研究：①解析Annexin A1与SCLC脑转移关系；②探明SCLC 分泌的Annexin A1如何调控血脑屏障微环境，适宜SCLC穿过血脑屏障迁移入脑及作用机制③尝试干预Annexin A1及相关分子功能，观察是否可以抑制SCLC脑转移发生。本项目的完成可为SCLC脑转移研究提供新的实验证据,有望为防治SCLC脑转移提供潜在作用靶点，丰富肿瘤器官特异性转移的"转移微环境"学说。

小细胞肺癌（SCLC）具有向脑特异性转移的特点，具体机制尚不清楚。以我们前期获得的具有不同脑转移能力的SCLC细胞间差异表达候选基因—膜联蛋白A1（Annexin A1）为研究对象，开展如下工作：解析Annexin A1与SCLC脑转移关系；探明SCLC 分泌的Annexin A1如何调控血脑屏障微环境，适宜SCLC穿过血脑屏障迁移入脑及作用机制；尝试干预Annexin A1及相关分子功能，观察是否可以抑制SCLC脑转移发生。本项目研究的重要结果如下,其一在原有课题研究内容上获得的研究结果:①从临床研究和实验室研究两个层面证明Annexin A1为介导SCLC细胞经血脑屏障转移入脑的相关因子，初步阐明Annexin A1在SCLC脑转移的临床意义；②干预Annexin A1的功能，可以降低裸鼠SCLC脑转移的发生；③分析SCLC源性AnnexinA1调控脑转移微环境中不同类型细胞表面相关粘附分子的表达特征，提出SCLC源性AnnexinA1可能以非受体介导途径调控了人脑微血管内皮细胞功能新的研究切入点，即SCLC外分泌的Annexin A1通过外泌体来调控脑血管内皮细胞的功能。④尝试建立不同层面的肿瘤转移微环境模型：建立体外血脑屏障与SCLC共培养模型，同时初步建立脑组织切片与SCLC细胞共生的模型，获得了初步结果。其二,在前述研究过程中获得了两个新的研究生长点，开展了拓展性、探索性的研究：①脑微血管内皮细胞源性外泌体能够上调SCLC细胞中S100A16的表达，维持SCLC细胞线粒体膜电位的稳定，维系其在脑内的生存。②处于脑血管微环境中的SCLC细胞不仅可以将Annexin A1外分泌到细胞外，也可以将Annexin A1结合蛋白S100A11外分泌到细胞外，以自分泌的方式调控SCLC细胞骨架蛋白actin的聚合促进肿瘤细胞迁移。本项目所获得的结果丰富SCLC脑转移的分子机制研究，为防治SCLC脑转移提供潜在可能靶点。此外，在本项目获得结果的提示下开展的“外泌体介导肿瘤器官特异性转移”的探索性研究，为肿瘤转移微环境的理论提供新的实验佐证。本项目获得的重要结果部分以标注资金资助形式已发表，尚有结果整理撰文发表中。