Oncogenic Function of Ca2+ Channel Orai1 in Esophageal Carcinogenesis

描述（申请人提供）：食管癌是全球第六大癌症死亡原因，90%以上的病例为食管鳞状细胞癌（ESCC）。在美国，这种疾病的总体5年生存率仅为13%，在所有癌症中排名第四。迫切需要确定有效的生物标志物，用于食管癌的早期检测、预后分层以及新的治疗干预措施。Ca2+信号失调与包括癌症在内的许多人类疾病有关。了解Ca2+可渗透通道的病理生理作用最近成为癌症研究的一个令人兴奋的领域。我们已经获得了令人兴奋的初步数据，表明质膜Ca2+通道Orai1作为一种致癌基因，通过调节细胞内Ca2+振荡来促进食管癌的进展。在ESCC患者切除的肿瘤中，我们检测到Orai1的表达升高，这与生存率低有关。在培养的人类ESCC细胞中，我们发现了细胞内Ca2+振荡的显著亢进，与非肿瘤细胞的静止性质形成鲜明对比。通过药理学或分子手段抑制Orai1可以利用高Ca2+振荡，从而抑制ESCC细胞的细胞增殖和迁移。此外，我们的初步数据显示，抑制Orai1可以阻止异种移植裸鼠的肿瘤生长。在这个项目中，我们假设Orai1介导的Ca2+振荡的过度活跃有助于食管上皮的癌变，并且靶向Orai1功能代表了治疗食管癌的潜在手段。首先，我们将确定Orai1-SOCE升高导致Ca2+振荡过度活跃的分子机制。接下来，我们将在体内明确Orai1在食管癌发生中的致癌作用。最后，我们将靶向Orai1-SOCE用于ESCC治疗。将采用多学科方法，包括活细胞成像，超微结构分析，细胞内Ca2+测量，强大的异种移植和致癌物质诱导的食管癌动物模型。该项目的创新之处在于首次研究了ESCC中Orai1的异常表达和细胞内Ca2+振荡的过度活跃，首次鉴定了介导上皮细胞内质网和质膜连接结构的分子，建立了一种新的转基因小鼠模型，在该模型中，Orai1的表达以诱导和可逆的方式被控制，特别是在食管上皮细胞中。该项目的结果将揭示orai1 - scoe - ca2 +振荡在食管癌发生中的作用的细胞机制理解。这些研究将为通过靶向Orai1通道活性治疗ESCC提供原理证明数据。

DESCRIPTION (provided by applicant): Esophageal cancer is the 6th leading cause of cancer death worldwide with more than 90% of all cases being esophageal squamous cell carcinoma (ESCC). The overall 5-year survival rate for this disease is only 13% in US, which is the fourth worst among all cancers. There is an urgent need to identify effective biomarkers for early detection, prognostic stratification as well as novel therapeutic interventions for esophageal cancer. Dysregulation in Ca2+ signaling has been linked to many human diseases including cancers. Understanding the pathophysiological roles of Ca2+ permeable channels has recently emerged as an exciting area of cancer research. We have obtained exciting preliminary data suggesting that Orai1, a plasma membrane Ca2+ channel, acts as an oncogene that contributes to the progression of esophageal cancer through regulation of intracellular Ca2+ oscillations. In tumors removed from patients with ESCC, we detected elevated expression of Orai1 which was associated with poor survival rate. In cultured human ESCC cells, we identified a striking hyperactivity in intracellular Ca2+ oscillations, in sharp contrast to the quiescent nature in non-tumor cells. Inhibition of Orai1 by either pharmacological or molecular means could harness hyper Ca2+ oscillations, which in turn suppress cell proliferation and migration in ESCC cells. Moreover, our preliminary data showed that inhibition of Orai1 prevents tumor growth in xenograft nude mice. In this project, we hypothesize that hyperactivity of Orai1-mediated Ca2+ oscillations contributes to carcinogenesis in esophageal epithelia, and targeting Orai1 function represents a potential means for treatment of esophageal cancer. First, we will identify the molecular mechanisms underlying the hyperactivity of Ca2+ oscillations resulting from elevated Orai1-SOCE. Next, we will define the oncogenic role of Orai1 during esophageal carcinogenesis in vivo. Lastly, we will target Orai1-SOCE for ESCC therapy. A multidisciplinary approach will be used including live cell imaging, ultrastructure analysis, intracellular Ca2+ measurement, robust xenograft and carcinogen-induced esophageal cancer animal models. The innovative aspects of this project include the first study on abnormal Orai1 expression and hyperactivity of intracellular Ca2+ oscillations in ESCC, identification of the first molecule mediating endoplasmic reticulum and plasma membranes junctional structures in epithelial cells, a novel transgenic mouse model in which the expression of Orai1 is controlled in an inducible and reversible manner specifically in esophageal epithelial cells. The outcome of this project will reveal the cellular mechanistic understanding of the role of Orai1-SOCE-Ca2+ oscillations in esophageal carcinogenesis. These studies will provide proof-of-principle data on therapeutic approach for ESCC by targeting Orai1 channel activity.