Department of Medicine, Rhode Island Hospital and Warren Alpert Medical School of Brown University, Providence, Rhode Island; and.
Department of Medicine, Rhode Island Hospital and Warren Alpert Medical School of Brown University, Providence, Rhode Island; and Department of Pathology, Rhode Island Hospital and Warren Alpert Medical School of Brown University, Providence, Rhode Island
Am J Physiol Gastrointest Liver Physiol. 2014 May 15;306(10):G863-72. doi: 10.1152/ajpgi.00321.2013. Epub 2014 Apr 3.
Mechanisms whereby acid reflux may accelerate the progression from Barrett's esophagus (BE) to esophageal adenocarcinoma (EA) are not fully understood. Acid and reactive oxygen species (ROS) have been reported to cause DNA damage in Barrett's cells. We have previously shown that NADPH oxidase NOX5-S is responsible for acid-induced H2O2 production in Barrett's cells and in EA cells. In this study we examined the role of intracellular calcium and NADPH oxidase NOX5-S in acid-induced DNA damage in a Barrett's EA cell line FLO and a Barrett's cell line CP-A. We found that pulsed acid treatment significantly increased tail moment in FLO and CP-A cells and histone H2AX phosphorylation in FLO cells. In addition, acid treatment significantly increased intracellular Ca(2+) in FLO cells, an increase that is blocked by Ca(2+)-free medium with EGTA and thapsigargin. Acid-induced increase in tail moment was significantly decreased by NADPH oxidase inhibitor diphenylene iodonium in FLO cells, and by blockade of intracellular Ca(2+) increase or knockdown of NOX5-S with NOX5 small-interfering RNA (siRNA) in FLO and CP-A cells. Acid-induced increase in histone H2AX phosphorylation was significantly decreased by NOX5 siRNA in FLO cells. Conversely, overexpression of NOX5-S significantly increased tail moment and histone H2AX phosphorylation in FLO cells. We conclude that pulsed acid treatment causes DNA damage via increase of intracellular calcium and activation of NOX5-S. It is possible that in BE acid reflux increases intracellular calcium, activates NOX5-S, and increases ROS production, which causes DNA damage, thereby contributing to the progression from BE to EA.
胃酸反流加速巴雷特食管（BE）向食管腺癌（EA）进展的机制尚未完全阐明。已有报道称，酸和活性氧（ROS）可导致 Barrett 细胞中的 DNA 损伤。我们之前的研究表明，NADPH 氧化酶 NOX5-S 负责 Barrett 细胞和 EA 细胞中酸诱导的 H2O2 产生。在这项研究中，我们研究了细胞内钙和 NADPH 氧化酶 NOX5-S 在酸诱导的 Barrett-EA 细胞系 FLO 和 Barrett 细胞系 CP-A 中 DNA 损伤中的作用。我们发现，脉冲酸处理显著增加了 FLO 和 CP-A 细胞的尾部矩和 FLO 细胞的组蛋白 H2AX 磷酸化。此外，酸处理显著增加了 FLO 细胞内的 Ca2+，用 EGTA 和 thapsigargin 处理的无 Ca2+培养基可阻断这种增加。在 FLO 细胞中，NADPH 氧化酶抑制剂二苯碘鎓（diphenylene iodonium）可显著降低酸诱导的尾部矩增加，而用细胞内 Ca2+增加阻断剂或用 NOX5 小干扰 RNA（siRNA）阻断 NOX5-S 在 FLO 和 CP-A 细胞中的表达可显著降低酸诱导的组蛋白 H2AX 磷酸化。在 FLO 细胞中，NOX5 siRNA 可显著降低酸诱导的组蛋白 H2AX 磷酸化。相反，NOX5-S 的过表达显著增加了 FLO 细胞中的尾部矩和组蛋白 H2AX 磷酸化。我们得出结论，脉冲酸处理通过增加细胞内钙和激活 NOX5-S 导致 DNA 损伤。在 BE 中，胃酸反流可能会增加细胞内钙，激活 NOX5-S，增加 ROS 产生，从而导致 DNA 损伤，进而促进从 BE 向 EA 的进展。
