Oncogenic Function of Ca2+ Channel Orai1 in Esophageal Carcinogenesis

描述(申请人提供)：食道癌是全球第六大癌症死亡原因，超过90%的病例是食道鳞癌(ESCC)。在美国，这种疾病的总体5年存活率只有13%，在所有癌症中排名第四。迫切需要寻找有效的生物标志物用于食道癌的早期检测、预后分层以及新的治疗干预措施。钙信号的失调与包括癌症在内的许多人类疾病有关。了解钙离子通透通道的病理生理作用最近已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振奋的初步数据，表明Orai1是一种质膜钙通道，它是一种癌基因，通过调节细胞内钙振荡而参与食道癌的进展。在ESCC患者切除的肿瘤中，我们检测到Orai1表达升高，这与低存活率有关。在培养的人ESCC细胞中，我们发现细胞内钙振荡明显过度活跃，这与非肿瘤细胞的静止特性形成鲜明对比。通过药物或分子手段抑制Orai1可以控制高钙振荡，进而抑制ESCC细胞的增殖和迁移。此外，我们的初步数据显示，抑制Orai1可以阻止裸鼠移植瘤的生长。在这个项目中，我们假设Orai1介导的钙振荡的过度活跃参与了食道上皮细胞的癌变，靶向Orai1功能可能是治疗食道癌的一种潜在手段。首先，我们将确定Orai1-SOCE升高导致的钙振荡过度活跃的分子机制。接下来，我们将确定Orai1在体内食道癌发生中的致癌作用。最后，我们将Orai1-SOCE作为ESCC治疗的靶点。将使用多学科方法，包括活细胞成像、超微结构分析、细胞内钙测量、健壮的异种移植和致癌物诱导的食道癌动物模型。该项目的创新之处包括首次研究Orai1在ESCC中的异常表达和细胞内钙振荡的高活性，鉴定了第一个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的表达是可诱导的和可逆的，尤其是在食道上皮细胞中。该项目的结果将揭示Orai1-SOCE-Ca~(2+)振荡在食管癌发生中的作用的细胞机制的理解。这些研究将提供针对Orai1通道活性的食管鳞癌治疗方法的原则证明数据。

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.