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.

项目总结/摘要 结直肠癌（CRC）是美国第三常见的癌症，也是导致癌症的第二大原因 癌症死亡，2015年估计有5万美国人死于CRC。过去几年的研究 几十年来已经揭示，肠道微生物群影响多种类型的癌症，包括CRC，最近 研究表明细菌基因毒素是癌症发生和发展的关键效应物。之一 与癌症最密切相关的细菌基因毒素是大肠杆菌素，它是人类肠道产生的代谢物， 阿格萨尔湖大肠杆菌菌株拥有一个被称为PKS岛的生物合成基因簇。增加的 pks+ E的丰度。大肠杆菌中发现的CRC和炎症性肠病（IBD）患者和pks+的能力 大肠杆菌素可能促进癌症的发生， 进展然而，实现大肠杆菌介导的DNA损伤的机制的理解， 遗传毒性由于无法分离这种代谢物或以其他方式分配其化学物质而受到阻碍， 结构这项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介导的致癌作用。初步结果 揭示了大肠杆菌素生物合成途径组装了在其他DNA中发现的结构特征， 破坏天然产品，导致大肠杆菌素的遗传毒性来自直接遗传毒性的假设 与DNA的相互作用为了验证这一观点，并获得确定大肠杆菌素的影响所需的关键知识， 我们的三个互补的具体目标是：1）阐明大肠杆菌素的化学结构， 整合多种分离策略; 2）破译大肠杆菌素暴露导致DNA 损伤;和3）鉴定抑制大肠杆菌素生物合成的小分子。这些进展将通过以下方式实现： 我们的多学科方法，它融合了有机化学，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。总的来说，这项工作将 产生阐明大肠杆菌素产生菌在CRC中的作用所需的工具和知识 在人类中的开始和发展。通过成功地证明研究和操纵个人 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 并验证我们未来的努力，以了解其他肠道微生物代谢活动如何影响CRC 启动和发展。