Molecular defense mechanisms of Barrett's metaplasia estimated by an integrative genomics. Homo sapiens

Barrett's esophagus is characterized by the replacement of squamous epithelium with specialized intestinal metaplastic mucosa. The exact mechanisms of initiation and development of Barrett's metaplasia remain unknown, but a hypothesis of successful adaptation against noxious reflux components has been proposed. To search for the repertoire of adaptation mechanisms of Barrett's metaplasia, we employed high-throughput functional genomic and proteomic methods that defined the molecular background of metaplastic mucosa resistance to reflux. Transcriptional profiling was established for 23 pairs of esophageal squamous epithelium and Barrett's metaplasia tissue samples using Affymetrix U133A 2.0 GeneChips and validated by quantitative real-time polymerase chain reaction. Differences in protein composition were assessed by electrophoretic and mass-spectrometry-based methods. Among 2,822 genes differentially expressed between Barrett's metaplasia and squamous epithelium, we observed significantly overexpressed metaplastic mucosa genes that encode cytokines and growth factors, constituents of extracellular matrix, basement membrane and tight junctions, and proteins involved in prostaglandin and phosphoinositol metabolism, nitric oxide production, and bioenergetics. Their expression likely reflects defense and repair responses of metaplastic mucosa, whereas overexpression of genes encoding heat shock proteins and several protein kinases in squamous epithelium may reflect lower resistance of normal esophageal epithelium than Barrett's metaplasia to reflux components. Despite the methodological and interpretative difficulties in data analyses discussed in this paper, our studies confirm that Barrett's metaplasia may be regarded as a specific microevolution allowing for accumulation of mucosal morphological and physiological changes that better protect against reflux injury. Department of Gastroenterology, Medical Center for Postgraduate Education and Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, 02-781 Warsaw, Poland Overall design: 2 types of tissue sample derived from the same patient: > Normal squamous epithelium (NE) from patients with longsegment of Barret’s epithelium > Metaplastic epithelium from Barrett’s esophagus (BE)

巴雷特食管（Barrett's esophagus）以鳞状上皮被特化肠上皮化生黏膜替代为特征。巴雷特化生（Barrett's metaplasia）的起始与发展的确切机制至今仍不明确，但已有假说提出其为机体对抗有害反流成分的适应性存活机制。为探究巴雷特化生的适应性机制谱，本研究采用高通量功能基因组学与蛋白质组学方法，明确了化生黏膜对抗反流损伤的分子基础。研究使用Affymetrix U133A 2.0基因芯片（Affymetrix U133A 2.0 GeneChips），对23对食管鳞状上皮与巴雷特化生组织样本开展转录谱分析，并通过实时定量聚合酶链反应（quantitative real-time polymerase chain reaction）对结果进行验证。蛋白质组成差异则通过电泳及基于质谱（mass-spectrometry）的方法进行评估。在2822个巴雷特化生与鳞状上皮间差异表达的基因中，研究人员观察到化生黏膜中显著高表达的基因，其编码产物包括细胞因子与生长因子、细胞外基质（extracellular matrix）、基底膜（basement membrane）及紧密连接（tight junctions）的组成成分，以及参与前列腺素、磷酸肌醇代谢、一氧化氮生成与生物能量学的蛋白质。这些基因的表达或反映了化生黏膜的防御与修复应答；而正常鳞状上皮中热休克蛋白（heat shock proteins）与多种蛋白激酶（protein kinases）编码基因的高表达，则可能提示正常食管上皮对反流成分的抵抗能力弱于巴雷特化生。尽管本文讨论了数据分析中存在的方法学与阐释难题，但本研究证实，巴雷特化生可被视为一种特异性微进化过程，可使黏膜在形态与生理层面发生累积性改变，从而更好地抵御反流损伤。波兰华沙02-781号，研究生教育医疗中心胃肠病学系与玛丽·斯克沃多夫斯卡-居里纪念癌症中心及肿瘤学研究所。实验总体设计：取自同一患者的两类组织样本：> 长段巴雷特上皮患者的正常鳞状上皮（NE）> 巴雷特食管（BE）来源的化生上皮