Department of Surgery, Vanderbilt University Medical Center and Vanderbilt-Ingram Cancer Center, Nashville, Tennessee, USA.
Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center and Vanderbilt-Ingram Cancer Center, Nashville, Tennessee, USA.
Sci Rep. 2017 Aug 30;7(1):9956. doi: 10.1038/s41598-017-09620-4.
Gastroesophageal reflux disease (GERD) is the strongest known risk factor for esophageal adenocarcinoma. In the center of tumorigenic events caused by GERD is repeated damage of esophageal tissues by the refluxate. In this study, we focused on a genotoxic aspect of exposure of esophageal cells to acidic bile reflux (BA/A). Analyzing cells generated from patients with Barrett's esophagus and human esophageal specimens, we found that BA/A cause significant DNA damage that is mediated by reactive-oxygen species. ROS originate from mitochondria and NADPH oxidases. We specifically identified NOX1 and NOX2 enzymes to be responsible for ROS generation. Inhibition of NOX2 and NOX1 with siRNA or chemical inhibitors significantly suppresses ROS production and DNA damage induced by BA/A. Mechanistically, our data showed that exposure of esophageal cells to acidic bile salts induces phosphorylation of the p47 subunit of NOX2 and its translocation to the cellular membrane. This process is mediated by protein kinase C, which is activated by BA/A. Taken together, our studies suggest that inhibition of ROS induced by reflux can be a useful strategy for preventing DNA damage and decreasing the risk of tumorigenic transformation caused by GERD.
胃食管反流病（GERD）是已知最强的食管腺癌风险因素。在 GERD 引起的肿瘤发生事件的中心，是反流物对食管组织的反复损伤。在这项研究中，我们专注于食管细胞暴露于酸性胆反流（BA/A）的遗传毒性方面。通过分析 Barrett 食管患者和人食管标本中的细胞，我们发现 BA/A 会导致由活性氧（ROS）介导的显著 DNA 损伤。ROS 源自线粒体和 NADPH 氧化酶。我们特别鉴定出 NOX1 和 NOX2 酶负责 ROS 的产生。用 siRNA 或化学抑制剂抑制 NOX2 和 NOX1 可显著抑制 BA/A 诱导的 ROS 产生和 DNA 损伤。从机制上讲，我们的数据表明，食管细胞暴露于酸性胆盐会诱导 NOX2 的 p47 亚基磷酸化及其向细胞膜的转位。这一过程由 BA/A 激活的蛋白激酶 C 介导。总之，我们的研究表明，抑制反流引起的 ROS 可以成为预防 DNA 损伤和降低 GERD 引起的肿瘤转化风险的有效策略。
