胆汁酸可直接增强巴雷特食管上皮中食管角质形成细胞尾侧相关同源框基因Cdx2的表达。
Bile acids directly augment caudal related homeobox gene Cdx2 expression in oesophageal keratinocytes in Barrett's epithelium.
作者信息
Kazumori H, Ishihara S, Rumi M A K, Kadowaki Y, Kinoshita Y
机构信息
Department of Gastroenterology and Hepatology, Shimane University, School of Medicine, 89-1 Enya-cho, Izumo, Shimane 693-8501, Japan.
出版信息
Gut. 2006 Jan;55(1):16-25. doi: 10.1136/gut.2005.066209. Epub 2005 Aug 23.
BACKGROUND AND AIMS
The mechanism of transformation to intestinal metaplasia in Barrett's oesophagus has not been clarified. We investigated the effects of various bile acids on expression of the caudal related homeobox gene Cdx2 in cultured oesophageal squamous epithelial cells. In addition, morphological and histochemical changes in squamous cells to intestinal epithelial cells were studied in response to bile acid induced expression of Cdx2.
METHODS
A rat model of Barrett's oesophagus was created by anastomosing the oesophagus and jejunum, and Cdx2 expression was investigated by immunohistochemistry. Also, the response of various bile acids on Cdx2 gene expression was studied in the human colon epithelial cell lines Caco-2 and HT-29, as well as in cultured rat oesophageal squamous epithelial cells using a Cdx2 promoter luciferase assay. In addition, primary cultured oesophageal squamous epithelial cells were transfected with Cdx2 expression vectors and their possible transformation to intestinal-type epithelial cells was investigated.
RESULTS
Oesophagojejunal anastomoses formed intestinal goblet cell metaplasia in rat oesophagus specimens and metaplastic epithelia strongly expressed Cdx2. When the effects of 11 types of bile acids on Cdx2 gene expression were examined, only cholic acid (CA) and dehydrocholic acid dose dependently increased Cdx2 promoter activity and Cdx2 protein production in Caco-2 and HT-29 cells, and cultured rat oesophageal keratinocytes. Results from mutation analysis of Cdx2 promoter suggested that two nuclear factor kappaB (NFkappaB) binding sites were responsible for the bile acid induced activation of the Cdx2 promoter. When bile acids were measured in oesophageal refluxate of rats with experimental Barrett's oesophagus, the concentration of CA was found to be consistent with the experimental dose that augmented Cdx2 expression in vitro. Furthermore, transfection of the Cdx2 expression vector in cultured rat oesophageal keratinocytes induced production of intestinal-type mucin, MUC2, in cells that expressed Cdx2.
CONCLUSIONS
We found that CA activates Cdx2 promoter via NFkappaB and stimulates production of Cdx2 protein in oesophageal keratinocytes with production of intestinal-type mucin. This may be one of the mechanisms of metaplasia in Barrett's oesophagus.
背景与目的
巴雷特食管向肠化生转变的机制尚未阐明。我们研究了各种胆汁酸对培养的食管鳞状上皮细胞中尾型相关同源盒基因Cdx2表达的影响。此外，还研究了胆汁酸诱导Cdx2表达后，鳞状细胞向肠上皮细胞的形态学和组织化学变化。
方法
通过食管与空肠吻合建立巴雷特食管大鼠模型，采用免疫组织化学法研究Cdx2表达。此外，使用Cdx2启动子荧光素酶测定法，研究了各种胆汁酸对人结肠上皮细胞系Caco-2和HT-29以及培养的大鼠食管鳞状上皮细胞中Cdx2基因表达的反应。此外，用Cdx2表达载体转染原代培养的食管鳞状上皮细胞，并研究其向肠型上皮细胞的可能转化。
结果
食管空肠吻合在大鼠食管标本中形成肠杯状细胞化生，化生上皮强烈表达Cdx2。当检测11种胆汁酸对Cdx2基因表达的影响时，只有胆酸（CA）和脱氢胆酸剂量依赖性地增加Caco-2和HT-29细胞以及培养的大鼠食管角质形成细胞中Cdx2启动子活性和Cdx2蛋白产生。Cdx2启动子突变分析结果表明，两个核因子κB（NFκB）结合位点负责胆汁酸诱导的Cdx2启动子激活。在实验性巴雷特食管大鼠的食管反流物中检测胆汁酸时，发现CA浓度与体外增加Cdx2表达的实验剂量一致。此外，在培养的大鼠食管角质形成细胞中转染Cdx2表达载体，在表达Cdx2的细胞中诱导产生肠型黏蛋白MUC2。
结论
我们发现CA通过NFκB激活Cdx2启动子，并刺激食管角质形成细胞中Cdx2蛋白产生以及肠型黏蛋白的产生。这可能是巴雷特食管化生的机制之一。
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