BARRETT'S ESOPHAGUS AND OXIDATIVE STRESS: ROLE OF GASTRIC ACID AND BILE ACID

巴雷特食管和氧化应激：胃酸和胆汁酸的作用

• 批准号: 7600487
• 负责人: Katerina Dvorak
• 金额: $ 33.55万
• 依托单位: UNIVERSITY OF ARIZONA
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7600487
• 关键词: 8-hydroxy-2' -deoxyguanosine; Acids; Acute; Antioxidants; Apoptosis; Apoptotic; Barrett Esophagus; Bile Acids; Biological Markers; Biopsy; Cell Line; Cell Membrane Permeability; Cells; Chemopreventive Agent; Chronic; Clinical Trials; DNA Repair; DNA repair protein; Data; Development; Distal; Dysplasia; Enrollment; Epithelial Cells; Esophageal; Esophageal Adenocarcinoma; Esophagus; Exposure to; Gastric Acid; Gastroesophageal reflux disease; Gene Mutation; Generations; Genomic Instability; Goals; Human Cell Line; Hydroxyl Radical; Image Analysis; Immunohistochemistry; In Vitro; Inflammatory; Injury; Lead; Lesion; Liver; Malignant neoplasm of esophagus; Mitochondria; Molecular; Neoplasms; Oxidative Stress; Pathogenesis; Patients; Pattern; Premalignant; Prevention; Preventive; Principal Investigator; Process; Production; Proteins; Reactive Oxygen Species; Reflux; Resistance; Resistance development; Role; Sample Size; Signal Pathway; Superoxide Dismutase; Superoxides; Testing; Ursodeoxycholic Acid; base; catalase; comparative genomic hybridization; cytotoxic; in vivo; lipid peroxidation inhibitor; mitochondrial membrane; novel; oxidative DNA damage; programs; protective effect; research study; response; survivin; tumor progression

Our major translational goal is to develop a chemopreventive strategy for inhibiting progression of Barrett's esophagus to esophageal adenocarcinoma. We hypothesize that the deleterious effects of hydrophobic bile acids and low pH may be inhibited by the cytoprotective bile acid, ursodeoxycholic acid (UDCA), that was shown to protect cells against oxidative injury. The central hypothesis to be tested in this proposal is that bile acids in combination with low pH induce oxidative stress that leads to DMA damage, genomic instability and apoptosis resistance in Barrett's esophagus. Therefore, an alteration of bile acid composition by ursodeoxycholic acid treatment may be beneficial to Barrett's esophagus patients in the prevention of neoplastic progression. Three specific aims are proposed to test this hypothesis. First, we will evaluate the effect of a bile acid cocktail and/or low pH on the generation of reactive oxygen species (ROS), oxidative, DNA damage, expression of DNA repair proteins, anti-oxidant and anti-apoptotic proteins in vitro in esophageal cell lines and ex vivo, in BE biopsies. We will determine the effect of acute, repeated and chronic exposure to bile acids and/or low pH (1) on the induction of superoxide, (2) formation of 8-OH-dG, a marker of oxidative DNA damage, (3) expression of DNA repair proteins (i.e. Mlh1, Pms2 and PARP), anti-oxidant (i.e. superoxide dismutases and catalase) and anti-apoptotic proteins (i.e. Mcl-1, survivin, Bcl-xL). Furthermore, we plan to identify patterns of DNA alterations using microarray-based comparative genomic hybridization (CGH) in novel esophageal cell lines developed for resistance to bile acids and/or low pH. In specific aim #2 we plan to evaluate the effects of UDCA and its conjugated forms [(tauro-ursodeoxycholic acid (TUDCA), glyco- ursodeoxycholic acid (GUDCA)] on ROS production, oxidative DNA damage, genomic instability and the expression of DNA repair proteins, anti-oxidant and anti-apoptotic proteins induced by low pH and cytotoxic bile acids in vitro. Since UDCA is an excellent scavenger of ROS we anticipate that UDCA will reduce damage caused by bile acids and low pH. Finally, in specific aim #3 we propose to conduct a pilot clinical trial to evaluate UDCA as a potential preventive agent that changes the composition of bile acids in the refluxate so that less toxic bile acids are refluxed to the esophagus. Thus, bile acid composition at the baseline and post UDCA treatment will be determined. Furthermore, markers of oxidative stress (8-OH-dG) and proliferation (Ki-67) will be assessed in BE biopsies at the baseline, 6 months on UDCA and 6 months after discontinuation of UDCA using immunohistochemistry in conjunction with image analysis. Our long-term goal is to evaluate factors and molecular mechanisms leading to BE development and/or progression to esophageal adenocarcinoma and to inhibit these processes.

我们的主要翻译目标是开发一种化学预防策略来抑制巴雷特病的进展 食管腺癌。我们假设疏水性胆汁的有害作用 细胞保护性胆汁酸熊去氧胆酸(UDCA)可以抑制酸性和低pH，即 被证明能保护细胞免受氧化损伤。 在这项提议中要检验的中心假设是胆汁酸与低pH值相结合会诱导 氧化应激导致Barrett‘s DNA损伤、基因组不稳定和细胞凋亡抵抗 食管。因此，熊去氧胆酸治疗对胆汁酸成分的改变可能是 有利于Barrett‘s食道患者预防肿瘤进展。 为了检验这一假说，本文提出了三个具体目标。首先，我们将评估胆汁酸的作用。 鸡尾酒和/或低pH对活性氧物种(ROS)的产生、氧化、DNA损伤、 DNA修复蛋白、抗氧化和抗凋亡蛋白在食道细胞系中的体外表达 和体外，在BE活组织检查。我们将确定急性、反复和慢性接触胆汁的影响。 酸和/或低pH(1)对超氧化物的诱导，(2)8-OH-DG的形成，这是DNA氧化的标志 损伤，(3)DNA修复蛋白(即MLH1、PMS2和PARP)的表达，抗氧化(即超氧化物 抗凋亡蛋白(Mcl-1、Survivin、Bclxl)。此外，我们计划 应用基于微阵列的比较基因组杂交(CGH)技术鉴定人类基因组DNA改变模式 为耐胆汁酸和/或低pH而开发的新型食道细胞系。在具体目标2中，我们计划 目的：评价UDCA及其结合物[牛磺酸-熊去氧胆酸(TUDCA)，糖基化胆酸]的作用。 熊去氧胆酸(GUDCA)对ROS产生、DNA氧化损伤、基因组不稳定性和 低pH和细胞毒诱导的DNA修复蛋白、抗氧化和抗凋亡蛋白的表达 胆汁酸在体外。由于UDCA是一种很好的ROS清除剂，我们预计UDCA将减少 胆汁酸和低pH值造成的损害。最后，在具体目标#3中，我们建议进行一项临床试验 评价UDCA作为一种潜在的预防性药物改变胆汁酸组成的试验 回流，使毒性较小的胆汁酸回流到食道。因此，胆汁酸的组成 将确定UDCA治疗的基线和治疗后。此外，氧化应激标志物(8-OH-DG) 和增殖(Ki-67)将在基线、UDCA治疗6个月和6个月时在BE活检中进行评估 UDCA停用后，应用免疫组织化学结合图像分析。 我们的长期目标是评估导致发育和/或 进展为食管腺癌，并抑制这些过程。