Asanuma Kiyotaka, Huo Xiaofang, Agoston Agoston, Zhang Xi, Yu Chunhua, Cheng Edaire, Zhang Qiuyang, Dunbar Kerry B, Pham Thai H, Wang David H, Iijima Katsunori, Shimosegawa Tooru, Odze Robert D, Spechler Stuart J, Souza Rhonda F
Esophageal Diseases Center, VA North Texas Health Care System and the University of Texas Southwestern Medical Center, Dallas, Texas, USA Departments of Medicine, VA North Texas Health Care System and the University of Texas Southwestern Medical Center, Dallas, Texas, USA Division of Gastroenterology, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.
Esophageal Diseases Center, VA North Texas Health Care System and the University of Texas Southwestern Medical Center, Dallas, Texas, USA Departments of Medicine, VA North Texas Health Care System and the University of Texas Southwestern Medical Center, Dallas, Texas, USA.
Gut. 2016 Sep;65(9):1416-26. doi: 10.1136/gutjnl-2015-309272. Epub 2015 May 18.
Barrett's metaplasia might develop if GORD causes oesophageal squamous cells to convert into columnar cells. Acid and bile exposures upregulate columnar differentiation genes like CDX2 in oesophageal squamous cells, but it is not known if such exposures downregulate squamous differentiation genes like SOX2. In addition to acid and bile, patients with GORD also have high oesophageal concentrations of nitric oxide (NO). This study aims to determine how acid, bile salts and NO affect genes that influence oesophageal cell phenotype.
Oesophageal squamous cells from patients with Barrett's oesophagus were exposed to acidic bile salts or NOC-9 (an NO donor). SOX2, p63 (squamous transcription factor) and CDX2 mRNAs were measured by quantitative RT-PCR. SOX2 and its regulatory Akt pathway proteins were evaluated by western blotting. S-nitrosylation by NO was blocked by dithiothreitol. Immunohistochemistry for SOX2 was performed on the oesophagus of rats with surgically induced GORD which were fed diets with and without nitrite supplementation.
In oesophageal squamous cells, NO profoundly decreased SOX2 protein and caused a significantly greater decrease in SOX2 mRNA than did acidic bile salts. NO also decreased p63 and increased CDX2 expression. NO caused S-nitrosylation of Akt, blocking its phosphorylation. Akt pathway inhibition by LY294002 or Akt siRNA reduced SOX2 mRNA. Rats fed with nitrite-supplemented diets exhibited weaker SOX2 oesophageal staining than rats fed with normal diets.
In oesophageal squamous cells, NO blocks SOX2 expression through Akt S-nitrosylation. NO also increases CDX2 and decreases p63 expression. By triggering molecular events preventing squamous differentiation while promoting intestinal differentiation, NO might contribute to Barrett's pathogenesis.
如果胃食管反流病（GORD）导致食管鳞状细胞转化为柱状细胞，可能会发生巴雷特化生。酸和胆汁暴露会上调食管鳞状细胞中如CDX2等柱状分化基因，但尚不清楚此类暴露是否会下调如SOX2等鳞状分化基因。除了酸和胆汁外，GORD患者食管中一氧化氮（NO）浓度也很高。本研究旨在确定酸、胆盐和NO如何影响影响食管细胞表型的基因。
将巴雷特食管患者的食管鳞状细胞暴露于酸性胆盐或NOC-9（一种NO供体）。通过定量逆转录聚合酶链反应（RT-PCR）测量SOX2、p63（鳞状转录因子）和CDX2信使核糖核酸（mRNA）。通过蛋白质免疫印迹法评估SOX2及其调节的Akt信号通路蛋白。二硫苏糖醇可阻断NO引起的S-亚硝基化。对手术诱导的GORD大鼠食管进行SOX2免疫组织化学检测，这些大鼠分别喂食添加和不添加亚硝酸盐补充剂的饲料。
在食管鳞状细胞中，NO显著降低SOX2蛋白水平，且导致SOX2 mRNA水平下降幅度明显大于酸性胆盐。NO还降低p63表达并增加CDX2表达。NO导致Akt发生S-亚硝基化，阻断其磷酸化。LY294002或Akt小干扰RNA（siRNA）抑制Akt信号通路可降低SOX2 mRNA水平。喂食添加亚硝酸盐补充剂饲料的大鼠食管SOX2染色比喂食正常饲料的大鼠弱。
在食管鳞状细胞中，NO通过Akt S-亚硝基化阻断SOX2表达。NO还增加CDX2表达并降低p63表达。通过引发阻止鳞状分化同时促进肠化生分化的分子事件，NO可能在巴雷特化生的发病机制中起作用。
