Understanding the Mechanism of a Gut Microbial Genotoxin Involved in Colorectal Carcinogenesis

了解肠道微生物基因毒素参与结直肠癌发生的机制

• 批准号: 9174570
• 负责人: Emily Patricia Balskus
• 金额: $ 39.82万
• 依托单位: HARVARD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-01 至 2021-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9174570
• 关键词: Affect; American; Anabolism; Animal Model; Bacteria; Biology; Cancer Etiology; Cell Line; Cells; Cellular biology; Cessation of life; Chemical Structure; Chemicals; Chromosomal Instability; Colitis; Collaborations; Colorectal Cancer; DNA; DNA Adducts; DNA Damage; DNA Double Strand Break; Development; Diagnosis; Disease; Engineering; Enzymatic Biochemistry; Escherichia coli; Eukaryotic Cell; Future; Gene Cluster; Goals; Human; In Vitro; Incidence; Individual; Infection; Inflammatory Bowel Diseases; Investigation; Island; Knowledge; Malignant Neoplasms; Mediating; Metabolic; Metabolic Pathway; Methodology; Methods; Microbiology; Molecular; Mus; Mutagens; Natural Products; Organic Chemistry; Outcome; Pathway interactions; Patients; Peptide Hydrolases; Production; Public Health; Research; Role; Structure; Techniques; Testing; Therapeutic Intervention; Toxicology; United States; Woman; Work; abstracting; cancer initiation; cancer prevention; cancer type; carcinogenesis; colon carcinogenesis; design; genotoxicity; gut microbiota; high throughput screening; in vivo; in vivo Model; inhibitor/antagonist; insight; interdisciplinary approach; men; microbial; microbiome; microbiota; microorganism; mouse model; prevent; programs; response; small molecule; tool; tumor progression; tumorigenesis

Project Summary / Abstract Colorectal cancer (CRC) is the third most prevalent form of cancer in the US and the second leading cause of cancer deaths, with an estimated 50,000 Americans succumbing to CRC in 2015. Studies over the last several decades have revealed that the gut microbiota influences multiple types of cancer, including CRC, and recent work has implicated bacterial genotoxins as key effectors in cancer development and progression. One of the bacterial genotoxins most strongly connected to cancer is colibactin, a metabolite produced by human gut commensal E. coli strains that possess a biosynthetic gene cluster dubbed the pks island. The increased abundance of pks+ E. coli found in CRC and inflammatory bowel disease (IBD) patients and the ability of pks+ strains to potentiate tumorigenesis in mouse models of CRC suggests that colibactin may promote cancer progression. However, achieving a mechanistic understanding of colibactin-mediated DNA damage and genotoxicity has been impeded by an inability to isolate this metabolite or otherwise assign its chemical structure. The overall objective of this proposal is to uncover the molecular mechanism underlying colibactin's genotoxic activity in order to understand and prevent colibactin-mediated carcinogenesis. Preliminary results have revealed that the colibactin biosynthetic pathway assembles structural features found in other DNA- damaging natural products, leading to the hypothesis that colibactin's genotoxicity arises from a direct interaction with DNA. To test this idea and obtain critical knowledge needed to ascertain colibactin's impact on CRC, our three complementary specific aims are to: 1) elucidate the chemical structure of colibactin by integrating multiple isolation strategies; 2) decipher the mechanism by which colibactin exposure leads to DNA damage; and 3) identify small molecules that inhibit colibactin biosynthesis. These advances will be enabled by our multidisciplinary approach, which merges knowledge and techniques from organic chemistry, chemical biology, biosynthesis and enzymology, microbiology, toxicology, and human cell biology. Overall, this effort will generate the tools and knowledge needed to elucidate the role of colibactin-producing bacteria in CRC initiation and progression in humans. By successfully demonstrating that studying and manipulating individual disease-associated microbial metabolic pathways can provide key mechanistic insights, this work will support and validate our future efforts to understand how other gut microbial metabolic activities influence CRC initiation and development.

项目概要/摘要 结直肠癌 (CRC) 是美国第三大常见癌症，也是导致人类死亡的第二大原因 癌症死亡，2015 年估计有 50,000 名美国人死于结直肠癌。过去几项研究 几十年来研究表明，肠道微生物群影响多种类型的癌症，包括结直肠癌和最近的癌症 研究表明细菌基因毒素是癌症发生和进展的关键效应物。中的一个 与癌症关系最密切的细菌基因毒素是大肠杆菌素，它是人类肠道产生的一种代谢物 共生大肠杆菌菌株，拥有被称为 pks 岛的生物合成基因簇。增加的 CRC 和炎症性肠病 (IBD) 患者中发现的 pks+ 大肠杆菌丰度以及 pks+ 的能力 在结直肠癌小鼠模型中增强肿瘤发生的菌株表明大肠杆菌素可能促进癌症 进展。然而，对大肠杆菌素介导的 DNA 损伤和 由于无法分离该代谢物或以其他方式分配其化学物质，遗传毒性受到阻碍 结构。该提案的总体目标是揭示大肠杆菌素的分子机制 基因毒性活性，以了解和预防大肠杆菌素介导的致癌作用。初步结果 已经揭示了大肠杆菌素生物合成途径组装了其他 DNA 中发现的结构特征 损害天然产物，导致假设大肠杆菌素的遗传毒性来自直接 与DNA的相互作用。为了测试这个想法并获得确定大肠杆菌素对 CRC，我们的三个互补的具体目标是：1）通过以下方式阐明大肠杆菌素的化学结构： 整合多种隔离策略； 2) 破译大肠杆菌素暴露导致DNA的机制 损害; 3) 鉴定抑制大肠杆菌素生物合成的小分子。这些进步将通过 我们的多学科方法融合了有机化学、化学 生物学、生物合成和酶学、微生物学、毒理学和人类细胞生物学。总体而言，这项努力将 生成阐明产生大肠杆菌素的细菌在结直肠癌中的作用所需的工具和知识 人类的起始和进展。通过成功地证明研究和操纵个体 与疾病相关的微生物代谢途径可以提供关键的机制见解，这项工作将支持 并验证我们未来努力了解其他肠道微生物代谢活动如何影响 CRC 启动和发展。