Department of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
Neoplasia. 2011 Sep;13(9):792-805. doi: 10.1593/neo.11788.
The incidence of esophageal adenocarcinoma (EAC) is rising in the United States. An important risk factor for EAC is the presence of Barrett esophagus (BE). BE is the replacement of normal squamous esophageal epithelium with a specialized columnar epithelium in response to chronic acid and bile reflux. However, the emergence of BE from squamous keratinocytes has not yet been demonstrated. Our research has focused on this. Wnt and cyclooxygenase 2 (Cox2) are two pathways whose activation has been associated with BE and progression to EAC, but their role has not been tested experimentally. To explore their contribution, we engineered a human esophageal keratinocyte cell line to express either a dominant-active Wnt effector CatCLef or a Cox2 complementary DNA. In a two-dimensional culture environment, Cox2 expression increases cell proliferation and migration, but neither transgene induces known BE markers. In contrast, when these cells were placed into three-dimensional organotypic culture conditions, we observed more profound effects. CatCLef-expressing cells were more proliferative, developed a thicker epithelium, and upregulated Notch signaling and several BE markers including NHE2. Cox2 expression also increased cell proliferation and induced a thicker epithelium. More importantly, we observed cysts form within the epithelium, filled with intestinal mucins including Muc5B and Muc17. This suggests that Cox2 expression in a three-dimensional culture environment induces a lineage of mucin-secreting cells and supports an important causal role for Cox2 in BE pathogenesis. We conclude that in vitro modeling of BE pathogenesis can be improved by enhancing Wnt signaling and Cox2 activity and using three-dimensional organotypic culture conditions.
食管腺癌（EAC）在美国的发病率正在上升。EAC 的一个重要危险因素是存在 Barrett 食管（BE）。BE 是正常鳞状食管上皮被一种特化的柱状上皮取代，以应对慢性酸和胆汁反流。然而，BE 从鳞状角质形成细胞中的出现尚未得到证实。我们的研究集中在这一点上。Wnt 和环氧化酶 2（Cox2）是两种途径，其激活与 BE 和进展为 EAC 有关，但它们的作用尚未经过实验测试。为了探索它们的贡献，我们设计了一种人食管角质形成细胞系，表达显性激活的 Wnt 效应物 CatCLef 或 Cox2 cDNA。在二维培养环境中，Cox2 表达增加细胞增殖和迁移，但这两种转基因均未诱导出已知的 BE 标志物。相比之下，当这些细胞被置于三维器官样培养条件下时，我们观察到了更深远的影响。CatCLef 表达的细胞增殖更多，形成更厚的上皮，并上调 Notch 信号和几种 BE 标志物，包括 NHE2。Cox2 表达也增加了细胞增殖并诱导了更厚的上皮。更重要的是，我们观察到上皮内形成了囊泡，充满了包括 Muc5B 和 Muc17 在内的肠粘蛋白。这表明 Cox2 在三维培养环境中的表达诱导了粘蛋白分泌细胞的谱系，并支持 Cox2 在 BE 发病机制中的重要因果作用。我们得出结论，通过增强 Wnt 信号和 Cox2 活性以及使用三维器官样培养条件，可以改进 BE 发病机制的体外模型。
