Aydar Ebru, Stratton Dan, Fraser Scott P, Djamgoz Mustafa B A, Palmer Christopher
Institute of Ophthalmology, University College London, 11/43 Bath Street, London, EC1V 9EL, UK.
Faculty of Life Sciences, London Metropolitan University, London, N7 8DB, UK.
Eur Biophys J. 2016 Oct;45(7):671-683. doi: 10.1007/s00249-016-1135-0. Epub 2016 May 9.
The main aim of this study was to investigate a possible functional connection between sigma-1 receptors and voltage-gated sodium channels (VGSCs) in human breast cancer cells. The hypothesis was that sigma-1 drugs could alter the metastatic properties of breast cancer cells via the VGSC. Evidence was found for expression of sigma-1 receptor and neonatal Na1.5 (nNa1.5) expression in both MDA-MB-231 and MDA-MB-468 cells. Sigma-1 drugs (SKF10047 and dimethyltryptamine) did not affect cell proliferation or migration but significantly reduced adhesion to the substrate. Silencing sigma-1 receptor expression by siRNA similarly reduced the adhesion. Blocking nNa1.5 activity with a polyclonal antibody (NESOpAb) targeting an extracellular region of nNa1.5 also reduced the adhesion in both cell lines. Importantly, the results of combined treatments with NESOpAb and a sigma-1 drug or sigma-1 siRNA suggested that both treatments targeted the same mechanism. The possibility was tested, therefore, that the sigma-1 receptor and the nNa1.5 channel formed a physical, functional complex. This suggestion was supported by the results of co-immunoprecipitation experiments. Furthermore, application of sigma-1 drugs to the cells reduced the surface expression of nNa1.5 protein, which could explain how sigma-1 receptor activation could alter the metastatic behaviour of breast cancer cells. Overall, these results are consistent with the idea of a sigma-1 protein behaving like either a "chaperone" or a regulatory subunit associated with nNa1.5.
本研究的主要目的是调查人乳腺癌细胞中σ-1受体与电压门控钠通道（VGSCs）之间可能存在的功能联系。假说是σ-1药物可通过VGSC改变乳腺癌细胞的转移特性。在MDA-MB-231和MDA-MB-468细胞中均发现了σ-1受体和新生儿型Na1.5（nNa1.5）表达的证据。σ-1药物（SKF10047和二甲基色胺）不影响细胞增殖或迁移，但显著降低了细胞与底物的黏附。用siRNA沉默σ-1受体表达同样降低了黏附。用靶向nNa1.5细胞外区域的多克隆抗体（NESOpAb）阻断nNa1.5活性也降低了两种细胞系中的黏附。重要的是，NESOpAb与σ-1药物或σ-1 siRNA联合处理的结果表明两种处理靶向相同的机制。因此，对σ-1受体和nNa1.5通道形成物理功能复合物的可能性进行了测试。共免疫沉淀实验的结果支持了这一推测。此外，将σ-1药物应用于细胞可降低nNa1.5蛋白的表面表达，这可以解释σ-1受体激活如何改变乳腺癌细胞的转移行为。总体而言，这些结果与σ-1蛋白表现为与nNa1.5相关的“伴侣”或调节亚基的观点一致。
