Determinants of AGR2 effects in Barrett's esophagus and esophageal adenocarcinoma

描述(申请人提供)：Barrett‘s食道是一种癌前病变，会增加患食管腺癌的风险。在上一次资助期间，基因表达分析显示，与正常食道组织相比，AGR2基因在Barrett‘s食道和食管腺癌中高表达。AGR2在其他多种腺癌中也有表达，包括结肠癌、胰腺癌、乳腺癌和前列腺癌。利用RNA干扰抑制Barrett相关的腺癌细胞系SEG-1中的基因表达，我们发现AGR2显示出与其他癌症重要基因相关的许多特性。在裸鼠体内移植后，SEG-1AGR2基因敲除细胞在软琼脂中的集落形成减少，生长减慢。在体外实验中，含有AGR2的组织培养上清液增加了细胞的迁移。AGR2在体外转化NIH3T3细胞的能力上也显示出与先前描述的癌基因相关的特征，例如病灶形成和在软琼脂中锚定独立生长的能力。对正常细胞中AGR2表达的研究表明，它的表达与整个胃肠道的肠腺细胞增殖区的分布一致。我们已经证实，分泌系的肠道细胞特异性地表达AGR2。结果表明，AGR2可能代表了胃肠系特异性干细胞与癌症之间的联系。在下一个资助期，我们建议阐明AGR2的S作用机制。我们将定义其作用所必需的AGR2蛋白结构域，其表达的基因组结构域和决定因素，以及其表达受AGR2影响的基因和蛋白质。AGR2的S效应很可能是通过激活信号转导通路来实现的，这些信号转导通路的同一性也将被确定。聚焦于AGR2的研究将为食道癌生物学提供有价值的见解，并有望成为治疗干预的靶点。许多其他表达AGR2的腺癌也可能受益于对该基因生物学的了解。公共卫生相关性：Barrett‘s食道是一种异常病变，常见于胃食道反流患者，通常表现为胃灼热。Barrett‘s食道的存在使人患食管腺癌的风险增加了40倍。我们的实验室最近对整个人类基因组进行了筛选，以寻找在巴雷特食道和腺癌中活跃的基因。我们发现一种名为AGR2的基因特别活跃。我们的实验室最近发现，一个活跃的AGR2基因促进了食道癌细胞的生长。我们还发现，AGR2基因在正常胃肠道中表达，通常与干细胞相关。这些干细胞在胃肠道中产生所有不同类型的细胞，并负责衰老细胞的正常替换。目前的假说认为，干细胞调控失控可能会导致癌症。更多的研究表明，表达AGR2的细胞属于肠道分泌谱系，这是一种发展为腺癌的细胞类型。这些数据支持AGR2在食管腺癌的发生发展中的重要作用。我们建议在下一个资金阶段确定AGR2如何促进Barrett‘s食管腺癌和食管腺癌的发展。我们将确定是什么细胞信号诱导AGR2的表达，以及AGR2本身诱导的信号通路。腺癌是一种腺癌，在结肠、胰腺、乳腺癌和前列腺癌中也很常见。由于AGR2基因在所有这些癌症中都是活跃的，对该基因的研究将增加我们对许多癌症潜在机制的了解，并为开发新的治疗策略提供机会。

DESCRIPTION (provided by applicant): Barrett's esophagus is a premalignant lesion that increases the risk for esophageal adenocarcinoma. During the last funding period, gene expression analysis revealed that compared to normal esophageal tissue, the AGR2 gene is highly expressed in Barrett's esophagus and esophageal adenocarcinoma. AGR2 is also expressed in a variety of other adenocarcinomas including colon, pancreatic, breast, and prostate cancers. Using RNA interference to repress gene expression in a Barrett's associated adenocarcinoma cell line, SEG-1, we established that AGR2 displays many properties associated with other genes important in cancer. SEG-1 AGR2 knockdown cells show a reduction in colony formation in soft agar and decreased growth as xenografts in nude mice. Tissue culture supernatant containing AGR2 increases cell migration in an in vitro assay. AGR2 also displayed features associated with previously described oncogenes in its ability to transform NIH3T3 cells in in vitro assays such as foci formation and the capacity for anchorage independent growth in soft agar. Studies of AGR2 expression in normal cells revealed that it is expressed in a distribution consistent with areas of cell proliferation in the intestinal crypts throughout the gastrointestinal tract. We have established that intestinal cells of secretory lineage specifically express AGR2. The results suggest that AGR2 may represent a link between gastrointestinal lineage-specific stem cells and cancer. During the next funding period, we propose to elucidate AGR2's mechanism of action. We will define the essential AGR2 protein domains required for its actions, the genomic domains and determinants for its expression, and the genes and proteins whose expression is affected by AGR2. It is likely that AGR2's effects are mediated via activation of signal transduction pathways, the identity of which will also be determined. Studies focused on AGR2 will provide valuable insights into esophageal cancer biology and serves as a promising target for therapeutic intervention. It is also likely that many other adenocarcinomas that express AGR2 will benefit from an understanding of this gene's biology. PUBLIC HEALTH RELEVANCE: Barrett's esophagus is an abnormal lesion commonly found in patients with gastroesophageal reflux, which commonly presents as heartburn. The presence of Barrett's esophagus increases one's risk for esophageal adenocarcinoma by up to 40-fold. Our laboratory recently performed a screen of the entire human genome looking for genes that are active in Barrett's esophagus and adenocarcinoma. We found a gene named AGR2 to be particularly active. Our laboratory has recently found that an active AGR2 gene promotes esophageal cancer cell growth. We also discovered that the AGR2 gene is expressed in the normal gastrointestinal tract in areas often associated with stem cells. These stem cells give rise to all the different cell types in the gastrointestinal tract and are responsible for the normal replacement of aged cells. Current hypotheses propose that deranged regulation of stem cells may give rise to cancer. Additional studies have revealed that cells expressing AGR2 belong to the secretory lineage of the intestine, which is the cell type that develops into adenocarcinomas. The data supports a significant role for AGR2 in the development of esophageal adenocarcinomas. We propose to determine during the next funding period how AGR2 promotes the development of Barrett's esophagus and esophageal adenocarcinoma. We will determine what cellular signals induce AGR2 expression as well as those signaling pathways that are induced by AGR2 itself. Adenocarcinomas are glandular cancers that are also common in the colon, pancreas, breast and prostate. Because the AGR2 gene is active in all these cancers, studies focused on this gene will increase our understanding of the mechanisms underlying many cancers and provide an opportunity for developing new therapeutic strategies.