Palme Daniela, Misovic Milan, Ganser Katrin, Klumpp Lukas, Salih Helmut R, Zips Daniel, Huber Stephan M
Department of Radiation Oncology, University Hospital Tübingen, Tübingen, Germany.
Clinical Collaboration Unit Translational Immunology, German Cancer Consortium (DKTK), University Hospital Tübingen, Tübingen, Germany.
Front Pharmacol. 2020 Apr 24;11:489. doi: 10.3389/fphar.2020.00489. eCollection 2020.
Many tumor cells express highly elevated activities of voltage-gated K channels in the plasma membrane which are indispensable for tumor growth. To test for K channel function during DNA damage response, we subjected human chronic myeloid leukemia (CML) cells to sub-lethal doses of ionizing radiation (0-8 Gy, 6 MV photons) and determined K channel activity, K channel-dependent Ca signaling, cell cycle progression, DNA repair, and clonogenic survival by whole-cell patch clamp recording, fura-2 Ca imaging, Western blotting, flow cytometry, immunofluorescence microscopy, and pre-plating colony formation assay, respectively. As a result, the human erythroid CML cell line K562 and primary human CML cells functionally expressed hERG1. Irradiation stimulated in both cell types an increase in the activity of hERG1 K channels which became apparent 1-2 h post-irradiation. This increase in K channel activity was paralleled by an accumulation in S phase of cell cycle followed by a G/M cell cycle arrest as analyzed between 8 and 72 h post-irradiation. Attenuating the K channel function by applying the hERG1 channel inhibitor E4031 modulated Ca signaling, impaired inhibition of the mitosis promoting subunit cdc2, overrode cell cycle arrest, and decreased clonogenic survival of the irradiated cells but did not affect repair of DNA double strand breaks suggesting a critical role of the hERG1 K channels for the Ca signaling and the cell cycle control during DNA damage response.
许多肿瘤细胞在质膜中表达电压门控钾通道的活性高度升高，这对肿瘤生长至关重要。为了测试DNA损伤反应期间钾通道的功能，我们将人慢性粒细胞白血病（CML）细胞暴露于亚致死剂量的电离辐射（0 - 8 Gy，6 MV光子），并分别通过全细胞膜片钳记录、fura - 2钙成像、蛋白质印迹、流式细胞术、免疫荧光显微镜和预铺板集落形成试验来测定钾通道活性、钾通道依赖性钙信号传导、细胞周期进程、DNA修复和克隆形成存活率。结果，人红系CML细胞系K562和原代人CML细胞功能性表达hERG1。辐射在两种细胞类型中均刺激hERG1钾通道活性增加，这在辐射后1 - 2小时变得明显。钾通道活性的这种增加与细胞周期S期的积累平行，随后在辐射后8至72小时分析发现出现G/M细胞周期停滞。通过应用hERG1通道抑制剂E4031减弱钾通道功能，可调节钙信号传导，损害对有丝分裂促进亚基cdc2的抑制，克服细胞周期停滞，并降低受辐射细胞的克隆形成存活率，但不影响DNA双链断裂的修复，这表明hERG1钾通道在DNA损伤反应期间的钙信号传导和细胞周期控制中起关键作用。
