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

描述(申请人提供)：胃食道反流病(GERD)影响超过十分之一的40岁以上的成年人和1/4的60岁以上的成年人。大约10%的GERD患者发生巴雷特食道(BE)，其中因反流性食管炎而受损的食道鳞状上皮被化生的肠型上皮取代。BE的特殊肠化生与发生食管腺癌的风险增加了近30-125倍。然而，从Barrett‘s食道(肠化生)到不典型增生和腺癌的进展机制尚不清楚。我们认为，在BE和腺癌中升高的活性氧物种(ROS)在BE向腺癌的发展中起着关键作用。初步数据表明，NADPH氧化酶亚型NOX5在腺癌细胞株(SEG1)中过表达，在那里它可能会过度产生ROS。因此，我们将检验这一中心假设，即酸暴露上调Barrett肠化生细胞中的NADPH氧化酶，导致自由基的产生，进而可能上调环氧合酶2(COX-2)和细胞周期蛋白D1。COX-2和Cyclin-D1的上调将促进这些化生细胞的增殖，减少细胞的凋亡。BE患者持续的酸反流可能会导致持续的变化，包括高水平的ROS，细胞增殖增加和细胞凋亡减少，这可能导致DNA损伤和突变增加，从而导致从化生到不典型增生和食管腺癌的进展。为了验证这一假说，我们将：1)检测NADPH氧化酶，尤其是NOX5，是否在酸暴露下在Barrett化生细胞和Seg1细胞中上调；2)检测钙和环AMP反应元件结合蛋白(CREB)是否介导酸诱导Barrett细胞系和Seg1细胞中NADPH氧化酶(尤其是NOX5)的表达；3)确定NADPH氧化酶产生的ROS在上调COX-2和Cyclin-D1中的作用。进一步了解酸诱导NADPH氧化酶尤其是NOX5上调导致细胞增殖增加和细胞凋亡减少的信号转导途径，可能为预防食管腺癌的发展提供合理的途径。

DESCRIPTION (provided by applicant): Gastroesophageal reflux disease (GERD) affects more than 1 in 10 adults over 40 years of age and 1 in 4 adults over 60. Approximately 10% of GERD patients develop Barrett's esophagus (BE) where esophageal squamous epithelium damaged by reflux esophagitis is replaced by a metaplastic, intestinal- type epithelium. The specialized intestinal metaplasia of BE is associated with nearly a 30-125-fold increased risk for the development of esophageal adenocarcinoma. However, the mechanisms of progression from Barrett's esophagus (intestinal metaplasia) to dysplasia and to adenocarcinoma are not known. We propose that reactive oxygen species (ROS), which are elevated in BE and in adenocarcinoma, play a key role in the progression from BE to adenocarcinoma. Preliminary data demonstrate that the NADPH oxidase isoform NOX5 is overexpressed in an adenocarcinoma cell line (SEG1) where it may overproduce ROS. We will therefore test the central hypothesis that acid exposure upregulates NADPH oxidases in Barrett's intestinal metaplastic cells, causing production of free radicals, which in turn may upregulate cyclooxygenase 2 (COX-2) and cyclin D1. Upregulation of COX-2 and cyclin-D1 will increase cell proliferation and decrease apoptosis in these metaplastic cells. Persistent acid reflux present in BE patients may cause continuous changes including high levels of ROS, increased cell proliferation and decreased apoptosis, which may lead to DNA damage and increased mutations contributing to the progression from metaplasia to dysplasia and to esophageal adenocarcinoma. To test this hypothesis we will: 1) Examine whether NADPH oxidases, in particular NOX5, are upregulated by acid exposure in Barrett's metaplastic cells and SEG1 cells; 2) Examine whether calcium and cyclic AMP response element binding protein (CREB) mediates acid-induced expression of NADPH oxidases (in particular NOX5) in a Barrett's cell line and in SEG1 cells; 3) Define the role of NADPH oxidases-generated ROS in upregulating COX-2 and cyclin-D1. A better understanding of the signal transduction pathway of acid induced upregulation of NADPH oxidases, in particular NOX5, leading to increased cell proliferation and decreased apoptosis, may provide a rational approach to the prevention of development of esophageal adenocarcinoma.