The College of Nanoscale Science and Engineering (CNSE), University at Albany, State University of New York, 257 Fuller Rd., Albany, NY 12203, USA.
Pflugers Arch. 2013 Sep;465(9):1249-60. doi: 10.1007/s00424-013-1254-8. Epub 2013 Mar 21.
The Ca(2+) sensor stromal interacting molecule 1 (STIM1) and the Ca(2+) channel Orai1 mediate the ubiquitous store-operated Ca(2+) entry (SOCE) pathway activated by depletion of internal Ca(2+) stores and mediated through the highly Ca(2+)-selective, Ca(2+) release-activated Ca(2+) (CRAC) current. Furthermore, STIM1 and Orai1, along with Orai3, encode store-independent Ca(2+) currents regulated by either arachidonate or its metabolite, leukotriene C4. Orai channels are emerging as important contributors to numerous cell functions, including proliferation, migration, differentiation, and apoptosis. Recent studies suggest critical involvement of STIM/Orai proteins in controlling the development of several cancers, including malignancies of the breast, prostate, and cervix. Here, we quantitatively compared the magnitude of SOCE and the expression levels of STIM1 and Orai1 in non-malignant human primary astrocytes (HPA) and in primary human cell lines established from surgical samples of the brain tumor glioblastoma multiforme (GBM). Using Ca(2+) imaging, patch-clamp electrophysiology, pharmacological reagents, and gene silencing, we established that in GBM cells, SOCE and CRAC are mediated by STIM1 and Orai1. We further found that GBM cells show upregulation of SOCE and increased Orai1 levels compared to HPA. The functional significance of SOCE was evaluated by studying the effects of STIM1 and Orai1 knockdown on cell proliferation and invasion. Utilizing Matrigel assays, we demonstrated that in GBM, but not in HPA, downregulation of STIM1 and Orai1 caused a dramatic decrease in cell invasion. In contrast, the effects of STIM1 and Orai1 knockdown on GBM cell proliferation were marginal. Overall, these results demonstrate that STIM1 and Orai1 encode SOCE and CRAC currents and control invasion of GBM cells. Our work further supports the potential use of channels contributed by Orai isoforms as therapeutic targets in cancer.
钙（Ca2+）传感器基质相互作用分子 1（STIM1）和 Ca2+通道 Orai1 介导普遍存在的储存操纵 Ca2+内流（SOCE）途径，该途径由内部 Ca2+储存耗尽激活，并通过高度 Ca2+选择性、Ca2+释放激活的 Ca2+（CRAC）电流介导。此外，STIM1 和 Orai1 以及 Orai3 编码不依赖储存的 Ca2+电流，这些电流受花生四烯酸或其代谢物白三烯 C4 调节。Orai 通道作为许多细胞功能的重要贡献者而出现，包括增殖、迁移、分化和凋亡。最近的研究表明，STIM/Orai 蛋白在控制几种癌症的发展中起着关键作用，包括乳腺癌、前列腺癌和宫颈癌。在这里，我们定量比较了非恶性人原代星形胶质细胞（HPA）和从脑肿瘤多形性胶质母细胞瘤（GBM）手术样本中建立的原代人细胞系中 SOCE 的幅度和 STIM1 和 Orai1 的表达水平。使用 Ca2+成像、膜片钳电生理学、药理学试剂和基因沉默，我们确定在 GBM 细胞中，SOCE 和 CRAC 由 STIM1 和 Orai1 介导。我们进一步发现，与 HPA 相比，GBM 细胞显示 SOCE 上调和 Orai1 水平增加。通过研究 STIM1 和 Orai1 敲低对细胞增殖和侵袭的影响，评估了 SOCE 的功能意义。利用 Matrigel 测定，我们证明在 GBM 中，但不在 HPA 中，STIM1 和 Orai1 的下调导致细胞侵袭显著减少。相比之下，STIM1 和 Orai1 敲低对 GBM 细胞增殖的影响微不足道。总体而言，这些结果表明 STIM1 和 Orai1 编码 SOCE 和 CRAC 电流，并控制 GBM 细胞的侵袭。我们的工作进一步支持 Orai 同工型通道作为癌症治疗靶点的潜在用途。
