NADPH oxidase-associated transition from Barrett's esophagus to adenocarcinoma

描述（由申请人提供）：胃食管反流病（GERD）影响超过十分之一的40岁以上成人和四分之一的60岁以上成人。大约10%的GERD患者发展为巴雷特食管（BE），这与食管腺癌（EA）发展风险增加近30-125倍有关。从BE进展到发育不良和EA的机制尚不清楚。因此，我们将研究一些可能参与这种进展的途径。活性氧（ROS）在BE和EA中升高，并且可能在BE向EA的进展中起关键作用。我们发现一种新的NADPH氧化酶NOX 5-S亚型在EA细胞系、EA组织和具有高度异型增生的BE粘膜中过表达。NOX 5-S首先在人胎儿肾脏中被鉴定，在其他组织中尚未被描述。在SEG 1 EA细胞中，脉冲酸暴露引起NOX 5-S的上调并增加H2 O2的产生。NOX 5-S衍生的ROS有助于增加SEG 1细胞的细胞增殖和减少细胞凋亡。然而，酸诱导的NOX 5-S上调和NOX 5-S依赖性的细胞增殖增加和凋亡减少的机制尚未完全了解。因此，我们将测试酸暴露通过激活Barrett化生细胞中的Rho激酶和MAP激酶上调NADPH氧化酶的假设，导致自由基的过度产生，这反过来又可能通过激活核因子κ B（NF-κ B）进一步增强NADPH氧化酶的表达。此外，ROS可能上调细胞周期蛋白D1和死亡结构域沉默物（SODD）。细胞周期蛋白D1和SODD的上调将增加这些细胞中的细胞增殖并减少细胞凋亡。因此，BE患者中存在的持续性酸反流可能导致高水平的ROS、增加的细胞增殖和减少的细胞凋亡，这可能导致DNA损伤和增加的突变，从而促进从BE到发育不良和EA的进展。为了检验这一假设，我们将：1）检查BE细胞系、Barrett粘膜活检和EA细胞（SEG 1、FLO和OE 33）中酸诱导的NADPH氧化酶表达的信号转导途径。我们将重点讨论Rho激酶、MAP激酶和NF-kB的作用。2)研究NADPH氧化酶依赖性的细胞增殖增加和细胞凋亡减少的机制，集中于细胞周期蛋白D1和SODD的作用，并研究NADPH氧化酶衍生的ROS是否导致DNA损伤。3)检查NOX 5-S发挥功能所需的调节蛋白，重点是Rac 1和p22 phox。更好地理解酸诱导的NADPH氧化酶上调的信号转导途径，导致细胞增殖增加和凋亡减少，可能提供一个合理的方法来预防EA的发展。此外，NOX 5-S可能是早期检测食管异型增生的潜在生物标志物。我们的模型也可能适用于其他炎症相关的癌症。 公共卫生相关性：这项提案研究了一种特殊的酶NOX 5-S在从巴雷特食管（Barrett's esophagus）发展到食管癌的过程中的作用，巴雷特食管是一种食管细胞因酸反流而改变的疾病。该项目旨在寻找潜在的治疗靶点，以防止这种进展。

DESCRIPTION (provided by applicant): Gastroesophageal reflux disease (GERD) affects more than one in ten adults over 40 years of age and one in four adults over 60. Approximately 10% of GERD patients develop Barrett's esophagus (BE), which is associated with nearly a 30-125-fold increased risk for the development of esophageal adenocarcinoma (EA). The mechanism of progression from BE to dysplasia and to EA is unknown. We will therefore examine some of the pathways that may be involved in this progression. Reactive oxygen species (ROS) are elevated in BE and EA, and may play a key role in the progression from BE to EA. We found that a novel isoform of NADPH oxidase NOX5-S is overexpressed in EA cell lines, EA tissues, and BE mucosa with high grade dysplasia. NOX5-S was first identified in human fetal kidney and has not been described in other tissues. In SEG1 EA cells pulsed acid exposure causes upregulation of NOX5-S and increases H2O2 production. NOX5-S-derived ROS contribute to increased cell proliferation and decreased apoptosis in SEG1 cells. However, the mechanisms of acid-induced NOX5-S upregulation and NOX5-S-dependent increase in cell proliferation and decrease in apoptosis are not fully understood. We will therefore test the hypothesis that acid exposure upregulates NADPH oxidases via activation of Rho kinases and MAP kinases in Barrett's metaplastic cells, causing overproduction of free radicals, which in turn may further enhance the expression of NADPH oxidases through activation of the nuclear factor kappaB (NF-kB). In addition, ROS may upregulate cyclin D1 and the silencer of the death domain (SODD). Upregulation of cyclin D1 and SODD will increase cell proliferation and decrease apoptosis in these cells. Thus the persistent acid reflux present in BE patients may cause high levels of ROS, increased cell proliferation and decreased apoptosis, which may lead to DNA damage and increased mutations, contributing to the progression from BE to dysplasia and to EA. To test this hypothesis we will: 1) Examine the signal transduction pathway of acid-induced expression of NADPH oxidases in a BE cell line, in Barrett's mucosal biopsies, and in EA cells (SEG1, FLO, and OE33). We will focus on the role of Rho kinase, MAP kinases and NF-kB. 2) Examine the mechanisms of NADPH oxidase-dependent increase in cell proliferation and decrease in apoptosis, concentrating on the role of cyclin D1 and SODD, and examine whether NADPH oxidase-derived ROS cause DNA damage. 3) Examine the regulatory proteins required for NOX5-S to function, focusing on Rac1 and p22phox. A better understanding of the signal transduction pathway of acid induced upregulation of NADPH oxidases, leading to increased cell proliferation and decreased apoptosis, may provide a rational approach to the prevention of development of EA. In addition, NOX5-S may be a potential biomarker for early detection of esophageal dysplasia. Our model may also be applicable to other inflammation-associated cancers. PUBLIC HEALTH RELEVANCE: This proposal studies the role of a particular enzyme NOX5-S in the progression from Barrett's esophagus, a condition where cells in the esophagus have been altered by acid reflux, to esophageal cancer. This project is designed to find potential therapeutic targets to prevent this progression.