The Molecular Functions of APE1 in Barrett's Tumorigenesis

APE1 在 Barrett 肿瘤发生中的分子功能

• 批准号: 9150515
• 负责人: WAEL EL-RIFAI
• 金额: $ 43.17万
• 依托单位: VANDERBILT UNIVERSITY MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-09-25 至 2020-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9150515
• 关键词: Affinity; Barrett Esophagus; Base Excision Repairs; Biological; Cells; Chronic; Cysteine; DNA; DNA Binding; DNA Binding Domain; DNA Damage; DNA lesion; Data; Development; Diagnostic; Esophageal Adenocarcinoma; Esophagus; Exposure to; Gastroesophageal reflux disease; Genes; Genetic Transcription; Incidence; Inflammation; Lead; Lesion; Molecular; Oncogenic; Oxidation-Reduction; Oxidative Stress; Precancerous Conditions; Property; Proteins; Reactive Oxygen Species; Reflux; Resistance; Risk Factors; Signal Transduction; Site; Structure; Therapeutic; Work; base; bile salts; cancer cell; carcinogenesis; chemotherapeutic agent; clinically significant; driving force; overexpression; prognostic; repaired; transcription factor; tumorigenesis

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. leads to the development of Barrett's esophagus (BE), a premalignant condition that is the main risk factor for EAC. We and others have shown that chronic exposure of BE cells to acidic bile salts induces inflammation and is associated with a dramatic increase in the burden of reactive oxygen species and oxidative stress: believed to be the main driving forces for disruption of cellular signaling mechanisms and the development of EAC. Exposure to oxidative stress can alter the redox status of reactive cysteine residues, located within the DNA-binding domain of some transcription factors (TFs), thereby modulating their activity and DNA binding affinity. Therefore, the cellular redox capacity is paramount in protecting these redox-sensitive TFs. The exposure of cells to oxidative agents and oxidative stress also leads to formation of pre-mutagenic apurinic/apyrimidinic (AP) sites in DNA molecules, which if unrepaired, lead to the formation and accumulation of additional DNA damage lesions, up to lethal levels. It is unknown how Barrett's and EAC can escape the oxidative effects of acidic bile salts reflux and also become resistant to currently used chemotherapeutic agents. APE1 is the only known protein with dual functions; 1) base excision repair (BER) activity, an important function for repair of oxidative DNA lesions, 2) redox-dependent functions that protect the cellular transcription machinery. In this proposal, we plan to characterize the molecular function(s) of APE1, a frequently overexpressed gene in EAC, in order to identify its biological, diagnostic, prognostic, and possibly therapeutic significance. Based on our preliminary data, we hypothesize that APE1 can promote the oncogenic pro-survival properties of Barrett's cancer cells through redox-dependent and independent (BER) functions. In aim 1, we will investigate the interplay between cellular localization, structure (BER and redox domains) and functions of APE1 in Barrett's carcinogenesis. In aim 2, we will examine the APE1-dependent redox functions in Barrett's carcinogenesis. The clinical significance and therapeutic potential of APE1 in EAC will be determined in aim 3. Upon completion of our work, we expect to unveil a new paradigm for the protective molecular mechanisms against oxidative stress in Barrett's carcinogenesis.

摘要/总结：过去三十年来，食管腺癌（EAC）的发病率增加了六倍多。慢性胃食管反流病 (GERD)，即酸性胆汁盐异常反流至食道。导致巴雷特食管 (BE) 的发展，这是一种癌前病变，也是 EAC 的主要危险因素。我们和其他人已经证明，BE 细胞长期暴露于酸性胆盐会诱发炎症，并与活性氧和氧化应激负担的急剧增加有关：被认为是破坏细胞信号传导机制和EAC 的发展。暴露于氧化应激可以改变位于某些转录因子 (TF) 的 DNA 结合域内的反应性半胱氨酸残基的氧化还原状态，从而调节其活性和 DNA 结合亲和力。因此，细胞氧化还原能力对于保护这些氧化还原敏感的转录因子至关重要。细胞暴露于氧化剂和氧化应激还会导致 DNA 分子中形成诱变前的无嘌呤/无嘧啶 (AP) 位点，如果不修复，则会导致额外 DNA 损伤病变的形成和积累，直至致命水平。目前尚不清楚 Barrett's 和 EAC 如何逃避酸性胆汁盐回流的氧化作用，并对目前使用的化疗药物产生耐药性。 APE1是唯一已知的具有双重功能的蛋白质； 1) 碱基切除修复 (BER) 活性，这是修复氧化 DNA 损伤的重要功能，2) 保护细胞转录机制的氧化还原依赖性功能。在本提案中，我们计划表征 APE1（EAC 中经常过度表达的基因）的分子功能，以确定其生物学、诊断、预后和可能的治疗意义。根据我们的初步数据，我们假设 APE1 可以通过氧化还原依赖性和独立 (BER) 功能促进 Barrett 癌细胞的致癌促生存特性。在目标 1 中，我们将研究 APE1 在巴雷特癌发生中的细胞定位、结构（BER 和氧化还原域）和功能之间的相互作用。在目标 2 中，我们将研究 Barrett 癌发生过程中 APE1 依赖性氧化还原功能。 APE1 在 EAC 中的临床意义和治疗潜力将在目标 3 中确定。完成我们的工作后，我们期望为 Barrett 癌发生中氧化应激的保护性分子机制揭示一个新的范例。