Copper ions are needed for several hallmarks of cancer. However, the involved pathways, mechanisms, and copper-binding proteins are mostly unknown. We recently found that cytoplasmic Antioxidant 1 copper chaperone (Atox1), which is up-regulated in breast cancer, is localized at the lamellipodia edges of aggressive breast cancer cells. To reveal molecular insights into a putative role in cell migration, we here investigated breast cancer cell (MDA-MB-231) migration by video microscopy as a function of Atox1. Tracking of hundreds of individual cells (per condition) over a 9-h time series revealed that cell migration velocity and directionality are significantly reduced upon Atox1 silencing in the cells. Because silencing of the copper transporter ATP7A also reduced cell migration, these proteins appear to be on the same pathway, suggesting that their well-known copper transport activity is involved. In-cell proximity ligation assays demonstrated that Atox1, ATP7A, and the proenzyme of lysyl oxidase (LOX; copper-loaded via ATP7A) are all in close proximity and that LOX activity is reduced upon Atox1 silencing in the cells. Since LOX is an established player in cancer cell migration, our results imply that Atox1 mediates breast cancer cell migration via coordinated copper transport in the ATP7A-LOX axis. Because individual cell migration is an early step in breast cancer metastasis, Atox1 levels in tumor cells may be a predictive measure of metastasis potential and serve as a biomarker for copper depletion therapy.

中文翻译：

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单细胞跟踪表明铜伴侣蛋白Atox1是乳腺癌细胞迁移所必需的。

铜离子是癌症的几个标志。但是，所涉及的途径，机制和铜结合蛋白大多是未知的。我们最近发现，在乳腺癌中上调的细胞质抗氧化剂1铜伴侣（Atox1）位于侵袭性乳腺癌细胞的片状脂膜边缘。为了揭示分子洞察力推测在细胞迁移中的作用，我们在这里通过视频显微镜研究了作为Atox1的功能的乳腺癌细胞（MDA-MB-231）迁移。在9小时的时间序列中跟踪数百个单个细胞（每个条件）显示，细胞中Atox1沉默后，细胞迁移速度和方向性显着降低。由于铜转运蛋白ATP7A的沉默也减少了细胞迁移，因此这些蛋白质似乎在同一路径上，提示它们参与了众所周知的铜迁移活动。细胞内邻近连接分析表明，Atox1，ATP7A和赖氨酰氧化酶的原酶（LOX；通过ATP7A负载铜）都非常接近，并且当细胞中Atox1沉默时，LOX活性会降低。由于LOX在癌细胞迁移中已确立地位，因此我们的研究结果表明Atox1通过ATP7A-LOX轴上协同的铜转运介导乳腺癌细胞迁移。由于单个细胞的迁移是乳腺癌转移的早期步骤，因此肿瘤细胞中Atox1的水平可能是转移潜力的预测指标，并可以作为铜耗竭疗法的生物标志物。铜通过ATP7A负载）非常接近，并且在细胞中Atox1沉默后，LOX活性降低。由于LOX在癌细胞迁移中已确立地位，因此我们的研究结果表明Atox1通过ATP7A-LOX轴上协同的铜转运介导乳腺癌细胞迁移。由于单个细胞的迁移是乳腺癌转移的早期步骤，因此肿瘤细胞中Atox1的水平可能是转移潜力的预测指标，并可以作为铜耗竭疗法的生物标志物。铜通过ATP7A负载）非常接近，并且在细胞中Atox1沉默后，LOX活性降低。由于LOX在癌细胞迁移中已确立地位，因此我们的研究结果表明Atox1通过ATP7A-LOX轴上协同的铜转运介导乳腺癌细胞迁移。由于单个细胞的迁移是乳腺癌转移的早期步骤，因此肿瘤细胞中Atox1的水平可能是转移潜力的预测指标，并可以作为铜耗竭疗法的生物标志物。