The role of calcium-sensitive potassium channels (KCa3.1) in non-small cell lung cancer progression

目前的项目旨在破译钙敏感性钾通道KCa3.1（由KCNN 4基因编码）促进非小细胞肺癌（NSCLC）进展的机制。我们在以前的工作中已经确定了KCa3.1通道启动子的低甲基化，因此通道蛋白的过表达是患者预后不良的强预测因子。肺癌，其中非小细胞肺癌（NSCLC）是最常见的亚型，是全世界癌症相关死亡的主要原因，5年存活率仅为~ 10%。大多数患者死于疾病的转移性扩散。因此，了解转移的机制具有重要的病理生理意义。所谓的转移性级联反应涉及循环肿瘤细胞与内皮的粘附及其随后在转移部位的跨内皮迁移等。虽然离子通道对肿瘤细胞凋亡、增殖和迁移的贡献已经得到了很好的研究，但它们在转移级联反应的不同步骤中的作用仍然很难理解。在这里，我们专注于钙敏感性钾通道KCa3.1。该通道通过控制NSCLC细胞的增殖、凋亡和迁移而促成NSCLC细胞的侵袭性表型。然而，到目前为止，关于KCa3.1通道驱动转移并由此决定患者预后的机制的知识非常有限。在本项目中，我们将研究KCa3.1通道在NSCLC转移级联的外渗步骤中的作用。KCa3.1通道在NSCLC和内皮细胞中均表达。我们假设KCa3.1通道调节NSCLC细胞与内皮的粘附以及它们的跨内皮迁移，来自NSCLC和内皮细胞的KCa3.1通道参与这一过程。我们将采用活细胞以及三维成像技术，原子力显微镜，微流体和转移的小鼠模型的组合。 KCa3.1通道依赖性机制将通过补充药理学、siRNA和/或敲除方法确定。我们希望证明KCa3.1通道（i）以ROS依赖性方式调节相关粘附分子的表达和功能，（ii）确定NSCLC细胞与内皮细胞的初始粘附与其血管内迁移至迁移部位的能力之间的微调平衡，以及（iii）使内皮细胞能够采用允许NSCLC细胞跨内皮迁移的机械特性。总之，我们的项目将提供进一步的证据表明，离子通道，长期以来被认为是重要的和容易药物靶点在其他疾病，如高血压，正在成为一类新的治疗靶点在肿瘤学。

The current project aims at deciphering mechanisms by which the calcium-sensitive potassium channel KCa3.1 (encoded by the KCNN4 gene) contributes to the progression of non-small cell lung cancer (NSCLC). We had identified in our previous work the hypomethylation of the KCa3.1 channel promoter and hence overexpression of the channel protein as strong predictors of a poor patient prognosis. Lung cancer, with non-small cell lung carcinoma (NSCLC) being the most frequent subtype, is a leading cause of cancer-related death worldwide with a 5 year survival rate of only ~10 %. Most patients die because of the metastatic spread of the disease. Thus, understanding mechanisms of metastasis is of great pathophysiological significance. The socalled metastatic cascade involves amongst others the adhesion of circulating tumor cells to the endothelium and their subsequent transendothelial migration at the site of metastasis. While the contribution of ion channels to tumor cell apoptosis, proliferation and migration has been well studied, their role in distinct steps of the metastatic cascade is still largely elusive. Here we focus on the calcium-sensitive potassium channel KCa3.1. The channel contributes to the aggressive phenotype of NSCLC cells by controlling their proliferation, apoptosis and migration. However, so far there is only very limited knowledge about the mechanisms by which KCa3.1 channels are driving metastasis and thereby determine patient prognosis. In the present project we will investigate the role of KCa3.1 channels in the extravasation step of the metastatic cascade in NSCLC. KCa3.1 channels are expressed both in NSCLC and in endothelial cells. We hypothesize that KCa3.1 channels are regulating the adhesion of NSCLC cells to the endothelium and their transendothelial migration with KCa3.1 channels from both, NSCLC and endothelial cells, being involved in this process. We will employ a combination of live-cell as well as 3D imaging techniques, atomic force microscopy, microfluidics and a murine model of metastasis. KCa3.1 channel-dependent mechanisms will be determined with a complimentary pharmacological, siRNA and/or knock-out approach. We want to show that KCa3.1 channels (i) regulate the expression and function of the relevant adhesion molecules in a ROS-dependent manner, (ii) ascertain the fine-tuned balance between initial adhesion of NSCLC cells to endothelial cells and their ability to migrate intravascularly to the site of transmigration, and (iii) enable endothelial cells to adopt mechanical properties permissive for transendothelial migration of NSCLC cells. Taken together, our project will provide further evidence that ion channels, long known as important and easily drugable targets in other pathologies such as hypertension, are emerging as a novel class of therapeutic targets in oncology.