Center for Cardiovascular Sciences, Albany Medical College, Albany, NY 12208, USA.
FASEB J. 2013 Jan;27(1):63-75. doi: 10.1096/fj.12-213801. Epub 2012 Sep 19.
Store-operated Ca(2+) entry (SOCE) encoded by Orai1 proteins is a ubiquitous Ca(2+)-selective conductance involved in cellular proliferation and migration. We recently described up-regulation of Orai3 channels that selectively mediate SOCE in estrogen receptor α-expressing (ERα(+)) breast cancer cells. However, the connection between ERα and Orai3 and the role of Orai3 in tumorigenesis remain unknown. Here, we show that ERα knockdown decreases Orai3 mRNA (by ∼63%) and protein (by ∼44%) with no effect on Orai1. ERα knockdown decreases Orai3-mediated SOCE (by ∼43%) and the corresponding Ca(2+) release-activated Ca(2+) (CRAC) current (by ∼42%) in ERα(+) MCF7 cells. The abrogation of SOCE in MCF7 cells on ERα knockdown can be rescued by ectopic expression of Orai3. ERα activation increased Orai3 expression and SOCE in MCF7 cells. Epidermal growth factor (EGF) and thrombin stimulate Ca(2+) influx into MCF7 cells through Orai3. Orai3 knockdown inhibited SOCE-dependent phosphorylation of extracellular signal-regulated kinase (ERK1/2; by ∼44%) and focal adhesion kinase (FAK; by ∼46%) as well as transcriptional activity of nuclear factor for activated T cells (NFAT; by ∼49%). Significantly, Orai3 knockdown selectively decreased anchorage-independent growth (by ∼58%) and Matrigel invasion (by ∼44%) of ERα(+) MCF7 cells with no effect on ERα(-) MDA-MB231 cells. Moreover, Orai3 knockdown inhibited ERα(+) cell tumorigenesis in immunodeficient mice (∼66% reduction in tumor volume). These data establish Orai3 as an ERα-regulated channel and a potential selective therapeutic target for ERα(+) breast cancers.
钙库操纵性钙内流（SOCE）由 Orai1 蛋白编码，是一种普遍存在的钙选择性电导，参与细胞增殖和迁移。我们最近描述了 Orai3 通道的上调，该通道选择性地介导雌激素受体α表达（ERα(+)）乳腺癌细胞中的 SOCE。然而，ERα 和 Orai3 之间的联系以及 Orai3 在肿瘤发生中的作用仍不清楚。在这里，我们表明 ERα 敲低会降低 Orai3 mRNA（约 63%）和蛋白（约 44%），而对 Orai1 没有影响。ERα 敲低会降低 ERα(+) MCF7 细胞中 Orai3 介导的 SOCE（约 43%）和相应的 Ca(2+)释放激活的 Ca(2+)（CRAC）电流（约 42%）。在 MCF7 细胞中，ERα 敲低后 SOCE 的阻断可以通过 Orai3 的异位表达来挽救。ERα 激活增加了 MCF7 细胞中 Orai3 的表达和 SOCE。表皮生长因子（EGF）和凝血酶通过 Orai3 刺激 MCF7 细胞内的 Ca(2+)内流。Orai3 敲低抑制了 SOCE 依赖性细胞外信号调节激酶（ERK1/2；约 44%）和粘着斑激酶（FAK；约 46%）的磷酸化以及激活的 T 细胞核因子（NFAT；约 49%）的转录活性。重要的是，Orai3 敲低选择性地降低了 ERα(+) MCF7 细胞的无锚定依赖性生长（约 58%）和 Matrigel 侵袭（约 44%），而对 ERα(-) MDA-MB231 细胞没有影响。此外，Orai3 敲低抑制了 ERα(+)细胞在免疫缺陷小鼠中的肿瘤发生（肿瘤体积减少约 66%）。这些数据确立了 Orai3 作为 ERα 调节的通道和 ERα(+)乳腺癌的潜在选择性治疗靶点。
