Hu Yingchuan, Williams Valerie A, Gellersen Oliver, Jones Carolyn, Watson Thomas J, Peters Jeffrey H
Department of Surgery, School of Medicine and Dentistry, University of Rochester, 601 Elmwood Ave, Rochester, New York 14642, USA.
J Gastrointest Surg. 2007 Jul;11(7):827-34. doi: 10.1007/s11605-007-0174-3.
Clinical evidence strongly suggests that bile acids are important in the development of Barrett's esophagus, although the mechanism remains unknown. Caudal-related homeobox 2 (CDX2) is a transcription factor recently implicated in early differentiation and maintenance of normal intestinal epithelium and is suggested to play a key role in the pathogenesis of intestinal metaplasia in Barrett's esophagus.
The aim of this study was to investigate the effect of primary and secondary bile acids on CDX2 mRNA expression in human esophageal cells.
Human esophageal cells: (1) squamous, immortalized by SV40 (Het-1A); (2) adenocarcinoma (SEG-1); and (3) squamous cell carcinoma (HKESC-1 & HKESC-2), were exposed in cell culture for 1-24 h to 100-1,000 microM deoxycholic, chenodeoxycholic, and glycocholic acids. Total RNA was extracted before and after bile acid treatment and reverse transcribed to cDNA. CDX2 mRNA expression was determined by both quantitative real-time and reverse transcription PCR (RT-PCR).
CDX2 mRNA expression was absent before bile acid exposure in all cell lines. CDX2 expression increased in a dose- and time-dependent fashion with deoxycholic and chenodeoxycholic, but not glycocholic, acid in all four cell lines. The maximal induction of CDX2 expression was seen in SEG-1 adenocarcinoma cells. Expression in Het-1A cells also increased significantly as did expression in HKESC-1,2 cells, although to a lesser extent than in adenocarcinoma.
These findings show that secondary bile acid stimulation upregulates CDX2 gene expression in both normal and cancer cell lines. They further support the role of bile acids in the pathogenesis of Barrett's esophagus and link the clinical evidence of a high prevalence of luminal bile acids in Barrett's to expression of the gene thought to be responsible for the phenotypic expression of intestinal metaplasia.
临床证据有力地表明，胆汁酸在巴雷特食管的发展中起着重要作用，尽管其机制尚不清楚。尾型相关同源盒2（CDX2）是一种转录因子，最近被认为与正常肠上皮的早期分化和维持有关，并被认为在巴雷特食管肠化生的发病机制中起关键作用。
本研究旨在探讨初级和次级胆汁酸对人食管细胞中CDX2 mRNA表达的影响。
人食管细胞：（1）经SV40永生化的鳞状细胞（Het-1A）；（2）腺癌（SEG-1）；（3）鳞状细胞癌（HKESC-1和HKESC-2），在细胞培养中暴露于100-1000微摩尔脱氧胆酸、鹅脱氧胆酸和甘氨胆酸1-24小时。在胆汁酸处理前后提取总RNA并逆转录为cDNA。通过定量实时和逆转录PCR（RT-PCR）测定CDX2 mRNA表达。
在所有细胞系中，胆汁酸暴露前均未检测到CDX2 mRNA表达。在所有四种细胞系中，脱氧胆酸和鹅脱氧胆酸可使CDX2表达呈剂量和时间依赖性增加，而甘氨胆酸则无此作用。在SEG-1腺癌细胞中观察到CDX2表达的最大诱导。Het-1A细胞中的表达也显著增加，HKESC-1、2细胞中的表达也增加，尽管程度低于腺癌细胞。
这些发现表明，次级胆汁酸刺激可上调正常和癌细胞系中CDX2基因的表达。它们进一步支持了胆汁酸在巴雷特食管发病机制中的作用，并将巴雷特食管管腔内胆汁酸高患病率的临床证据与被认为负责肠化生表型表达的基因表达联系起来。
