Bhardwaj Vikas, Horvat Andela, Korolkova Olga, Washington Mary K, El-Rifai Wael, Dikalov Sergey I, Zaika Alexander I
Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, TN 37212, USA.
Department of Surgery.
Carcinogenesis. 2016 Dec;37(12):1161-1169. doi: 10.1093/carcin/bgw100. Epub 2016 Sep 21.
Esophageal adenocarcinoma (EA) is one of the fastest rising tumors in the USA. The major risk factor for EA is gastroesophageal reflux disease (GERD). During GERD, esophageal cells are exposed to refluxate which contains gastric acid frequently mixed with duodenal bile. This may lead to mucosal injury and Barrett's metaplasia (BE) that are important factors contributing to development of EA. In this study, we investigated DNA damage in BE cells exposed to acidic bile salts and explored for potential protective strategies. Exposure of BE cells to acidic bile salts led to significant DNA damage, which in turn, was due to generation of reactive oxygen species (ROS). We found that acidic bile salts induce a rapid increase in superoxide radicals and hydrogen peroxide, which were determined using electron paramagnetic resonance spectroscopy and Amplex Red assay. Analyzing a panel of natural antioxidants, we identified apocynin to be the most effective in protecting esophageal cells from DNA damage induced by acidic bile salts. Mechanistic analyses showed that apocynin inhibited ROS generation and increases the DNA repair capacity of BE cells. We identified BRCA1 and p73 proteins as apocynin targets. Downregulation of p73 inhibited the protective effect of apocynin. Taken together, our results suggest potential application of natural compounds such as apocynin for prevention of reflux-induced DNA damage and GERD-associated tumorigenesis.
食管腺癌（EA）是美国发病率上升最快的肿瘤之一。EA的主要危险因素是胃食管反流病（GERD）。在GERD期间，食管细胞暴露于反流物中，反流物中含有经常与十二指肠胆汁混合的胃酸。这可能导致黏膜损伤和巴雷特化生（BE），而这是促成EA发生的重要因素。在本研究中，我们调查了暴露于酸性胆汁盐的BE细胞中的DNA损伤，并探索了潜在的保护策略。BE细胞暴露于酸性胆汁盐会导致显著的DNA损伤，而这又归因于活性氧（ROS）的产生。我们发现酸性胆汁盐会使超氧自由基和过氧化氢迅速增加，这是通过电子顺磁共振光谱和Amplex Red测定法确定的。通过分析一组天然抗氧化剂，我们确定阿朴西林在保护食管细胞免受酸性胆汁盐诱导的DNA损伤方面最为有效。机制分析表明，阿朴西林抑制ROS的产生并提高BE细胞的DNA修复能力。我们确定BRCA1和p73蛋白是阿朴西林的作用靶点。p73的下调抑制了阿朴西林的保护作用。综上所述，我们的结果表明天然化合物如阿朴西林在预防反流诱导的DNA损伤和GERD相关肿瘤发生方面具有潜在应用价值。
