The role of NRF2 in reflux-induced esophageal adenocarcinomas

摘要/总结：食管腺癌（EAC）的发病率增加了6 在过去的三十年里，慢性胃食管反流病（GERD），其中酸性胆汁盐 异常反流进入食道影响几乎20%的美国成年人口。GERD导致 腺上皮的发展称为巴雷特食管（BE）; 发生肿瘤性病变;高度异型增生（HGD）和进展为EAC。我们和其他人已经 表明BE细胞长期暴露于酸性胆汁盐与负荷的急剧增加有关， 活性氧（ROS）和氧化应激。我们发现，一些成员的 在BE细胞中保护免受氧化应激的谷胱甘肽家族成员在肿瘤性HGD中沉默， EAC.由于慢性酸性胆汁反流，EAC细胞暴露于高水平的ROS和氧化应激， 致癌基因的激活。如果不能控制ROS和氧化应激的累积水平， 癌细胞，如果他们仍然没有得到纠正。我们假设，随着几个抗氧化基因的沉默， 在从BE到HGD/EAC的发展过程中，癌细胞必须发展一种抗氧化网络， ROS的不受控制的积累。这些适应机制对于促进它们在环境中的生存至关重要。 由于暴露于酸性胆汁盐、癌基因激活和治疗，对高水平ROS的反应 化疗药物。我们的初步数据表明，NRF 2在细胞中的组成性高水平表达。 HGD/EAC，表明其作为一种内在的适应性分子机制的作用。我们第一次发现 EAC中NRF 2蛋白的积累及其活化主要依赖于氧化还原因子1（REF 1）;而不是 其生理抑制剂KEAP 1。在这个提议中，我们将研究NRF 2的生物学相关性， 抗氧化剂在调节ROS、氧化应激、氧化性DNA损伤、基因表达和细胞中的功能， 对酸性胆汁盐和化疗药物的反应。REF 1对NRF 2的调控及其机制 转录网络将在目标1中进行研究。在目标2中，我们将解决NRF 2以前未探索的角色 在EAC肿瘤发生中的作用，并确定NRF 2在EAC癌细胞存活中对酸性胆汁盐的反应 和化疗药物。NRF 2表达的临床病理意义及其作为肿瘤标志物的意义 将单独和与现有的化学治疗剂组合研究可药物化的靶点（目标3）。在 总之，这个项目解决了我们知识的空白，并解决了基于病因的生物学相关问题。 关于NRF 2在调节生存和化疗中的作用的新信息的问题 EAC中的电阻。这些发现尤其重要，因为几种NRF 2激活剂可在 也用于治疗一些临床疾病，如多发性硬化症（MS）。治疗 在MS和BE患者中，可能需要仔细监测NRF 2激活剂，因为它们可能在 EAC的风险更高，因为在这种情况下NRF 2的促肿瘤发生作用。我们的研究结果也可以支持 NRF 2抑制剂的开发，并为EAC治疗提供了新的治疗机会窗口。

ABSTRACT/SUMMARY: The incidence of esophageal adenocarcinoma (EAC) has increased more than six fold over the past three decades. Chronic gastroesophageal reflux disease (GERD), where acidic bile salts abnormally refluxate into the esophagus affects almost 20% of adult US population. GERD leads to the development of a glandular epithelium known as Barrett's esophagus (BE); the main risk factor for the development of neoplastic lesions; high-grade dysplasia (HGD) and progression to EAC. We and others have shown that chronic exposure of BE cells to acidic bile salts is associated with a dramatic increase in the burden of reactive oxygen species (ROS) and oxidative stress. We have found that several members of the glutathione family members that protect against oxidative stress in BE cells are silenced in neoplastic HGD and EAC. EAC cells are exposed to high levels of ROS and oxidative stress due to chronic acidic bile reflux and activation of oncogenes. Failure to control the cumulative levels of ROS and oxidative stress would be lethal to cancer cells, if they remain uncorrected. We hypothesize that; with the silencing of several antioxidant genes in progression from BE to HGD/EAC, cancer cells must develop an antioxidant network that prevents uncontrolled accumulation of ROS. These adaptive mechanisms are crucial in promoting their survival in response to high levels of ROS due to exposure to acidic bile salts, activation of oncogenes, and treatment with chemotherapeutics. Our preliminary data demonstrated constitutive high levels of expression of NRF2 in HGD/EAC, suggesting its role as an intrinsic adaptive molecular mechanism. We show for the first time that accumulation of NRF2 protein and its activation in EAC is mainly dependent on redox factor 1 (REF1); not on its physiological inhibitor KEAP1. In this proposal, we will investigate the biological relevance of NRF2 antioxidant functions in regulating ROS, oxidative stress, oxidative DNA damage, gene expression, and cell survival in response to acidic bile salts and chemotherapeutics. The regulation of NRF2 by REF1 and its transcription network will be investigated in Aim 1. In Aim 2, we will tackle previously unexplored roles of NRF2 in EAC tumorigenesis and identify the role of NRF2 in EAC cancer cell survival in response to acidic bile salts and chemotherapeutics. The clinico-pathological significance of NRF2 expression and its significance as a druggable target will be investigated alone and in combination with existing chemotherapeutics (Aim 3). In summary, this project addresses gaps in our knowledge and tackles etiology-based biologically relevant questions to uncover novel information regarding the role of NRF2 in regulating survival and chemotherapeutic resistance in EAC. The findings are especially important as several NRF2 activators are available over the counter and are also used to treat some clinical disorders such multiple sclerosis (MS). Treatments with NRF2 activators may need to be carefully monitored in patients with MS and BE, as they could be at higher risk for EAC because of NRF2 pro-tumorigenic effects in this setting. Our results could also support the development of NRF2 inhibitors and provide a novel window of therapeutic opportunity for EAC treatment.