The Role of Secondary Bile Acids in Gastro-Esophageal Neoplasia

项目总结 胃食道交界处的干细胞和祖细胞(GEJ)已被确认为对 发生在远端食道、胃食道交界处和近端胃的腺癌。 这些癌症加在一起，在美国每年有超过2万个新病例，与高死亡率相关，而且 这是一个重大的公共卫生负担。我们的小组已经确认了胃和胃移行细胞癌 基底干细胞可能是该地区癌前状态的起源细胞。然而，定义这些机制 而驱动GE连接干细胞命运并促进癌症发展的效应器仍然是一个关键缺口 知识。Barrett‘s食道(BE)和食管腺癌(EAC)代表了 GE结合部干细胞引起的肿瘤。我们有大量的初步数据表明 来自肠道细菌的次级胆汁酸直接促进BE和EAC的发展，治疗我们的 L2-IL1B小鼠BE/EAC模型加去氧胆酸(DCA)促瘤作用 乙酰胆酸是核胆酸受体FXR(法尼醇X受体)的激动剂，可抑制细胞增殖， GEJ干细胞数量和异型增生。然而，次级胆汁酸影响的确切机制 GEJ干细胞和相关的微环境尚未阐明。我们假设这个循环 肠道细菌产生的次级胆汁酸通过直接作用于GE促进早期癌症的发展 连接干细胞通过FXR拮抗和诱导促炎微环境改变。 使用高度新颖的技术和方法(包括scRNA-Seq和CyTOF)，我们将执行一系列 使用小鼠模型、小鼠和人类有机化合物进行实验，并在前瞻性研究中验证发现 对患者的研究，以解决以下具体目标：目的1.确定循环次级循环的作用 胆汁酸在GEJ上皮干细胞去向和早期癌症促进中的作用；目的2.评估循环的影响 次级胆汁酸对GEJ上皮干细胞微环境的影响；目的3.确定靶向 调节循环胆汁酸池的微生物组修饰改变了GEJ癌症的发展。至 为了实现这些目标，我们将使用我们独特的L2-IL1B小鼠模型，在干细胞中进行FXR基因敲除(L2-IL1B) IL1B/Fxrfl/fl)，使我们能够评估次级胆汁酸对GEJ干细胞以及L2-IL1B/Nlrpfl/fl的影响 探索干细胞中炎性小体激活的模型，并评估与微环境的串扰。 最终，我们将对不同的高度特征化的细菌菌株进行治疗实验。 调节肠道微生物群的次级胆汁酸生成能力，并确定其对机体的影响。 源于GE结合部干细胞的癌症。继发性胆汁的特殊机制的阐明 酸与GEJ干细胞相互作用并改变微环境以促进癌症发展可能导致 确定新的治疗靶点，包括合理设计益生菌疗法的可能性， 这将对公众健康产生重大影响。

PROJECT SUMMARY Stem and progenitor cells at the gastroesophageal junction (GEJ) have been identified as crucial to the development of adenocarcinoma of the distal esophagus, gastroesophageal junction, and proximal stomach. Combined, these cancers have over 20,000 new cases per year in the U.S., are associated high mortality, and represent a major public health burden. Our group has identified both gastric cardia as well as GEJ transitional basal stem cells as likely cells of origin for precancerous states in this region. However, defining the mechanisms and effectors that drive GE junction stem cell fate and promote cancer development remains a critical gap in knowledge. Barrett’s esophagus (BE) and esophageal adenocarcinoma (EAC) represent the prototype for neoplasia arising from GE junction stem cells. We have extensive preliminary data demonstrating that circulating secondary bile acids derived from gut bacteria directly promote the development of BE and EAC, treating our L2-IL1B mouse model of BE/EAC with deoxycholic acid (DCA) accelerates neoplasia, and treatment with obeticholic acid, an agonist of nuclear bile acid receptor FXR (farnesoid X receptor), decreases proliferation, GEJ stem cell numbers, and dysplasia. However, the exact mechanisms by which secondary bile acids impact GEJ stem cells and the associated microenvironment have not been elucidated. We hypothesize that circulating secondary bile acids produced by gut bacteria promote early cancer development via direct effects on GE junction stem cells through FXR antagonism and by inducing pro-inflammatory microenvironment alterations. Using highly novel techniques and approaches (including scRNA-Seq and CyTOF), we will perform a series of experiments using mouse models, mouse and human organoids, and with validation of findings in a prospective study of patients, to address the following specific aims: Aim 1. To determine the role of circulating secondary bile acids in GEJ epithelial stem cell fate and early cancer promotion; Aim 2. To assess the effects of circulating secondary bile acids on the GEJ epithelial stem cell microenvironment; Aim 3. To determine whether targeted microbiome modification that regulates the circulating bile acid pool modifies GEJ cancer development. To achieve these aims we will use our unique L2-IL1B mouse model with FXR knockout in stem cells (L2- IL1B/Fxrfl/fl), allowing us to assess the effects of secondary bile acids on GEJ stem cells as well the L2-IL1B/Nlrpfl/fl model to explore inflammasome activation in stem cells and assess for cross-talk with the microenvironment. Ultimately, we will perform experiments treating with distinct consortia of highly characterized bacterial strains to modulate the secondary bile acid producing capacity of the gut microbiome and determine the effects on cancers arising from GE junction stem cells. Elucidation of the specific mechanisms by which secondary bile acids interact with GEJ stem cells and modify the microenvironment to promote cancer development may lead to the identification of novel therapeutic targets, including the potential for rationally designed probiotic therapy, which would have a major public health impact.