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: 10316686
• 负责人: Emily Patricia Balskus
• 金额: $ 38.43万
• 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 2026-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10316686
• 关键词: Achievement; Affect; Alkylating Agents; American; Anabolism; Animal Model; Biological; Biology; Boronic Acids; Cancer Biology; Cancer Etiology; Cells; Cessation of life; Chemicals; Chromosomal Instability; Colitis associated colorectal cancer; Colorectal Cancer; DNA; DNA Adducts; DNA Damage; DNA Double Strand Break; DNA Sequence Alteration; Development; Diagnosis; Disease; Enzymes; Escherichia coli; Eukaryotic Cell; Exposure to; Funding; Future; Gene Cluster; Genome; Goals; Grant; Human; Human Cell Line; Human Microbiome; In Vitro; Incidence; Individual; Infection; Inflammatory Bowel Diseases; Island; Knowledge; Location; Malignant Neoplasms; Mediating; Metabolic Pathway; Metabolism; Methods; Microbiology; Molecular; Mus; Mutagens; Pathway interactions; Patients; Physiological; Play; Prevalence; Production; Proteobacteria; Public Health; Research; Role; Specificity; Structure; Techniques; Toxicology; United States; Woman; Work; animal tissue; cancer initiation; cancer prevention; cancer therapy; carcinogenesis; colon cancer patients; colon carcinogenesis; colorectal cancer prevention; commensal bacteria; crosslink; genotoxicity; guided inquiry; gut bacteria; gut microbes; gut microbiota; host-associated microbial communities; in vivo Model; inhibitor/antagonist; insight; interdisciplinary approach; men; microbial; microbial community; microbiome research; mouse model; peptide synthase; polyketide synthase; prevent; programs; small molecule; small molecule inhibitor; structural biology; tumor progression; tumorigenesis

PROJECT SUMMARY Colorectal cancer (CRC) is the third most prevalent form of cancer in the US and the second leading cause of cancer deaths. Studies over the last several decades have revealed that the gut microbiota influences CRC, and recent work has implicated gut 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 bacteria, including certain E. coli strains, that possess a biosynthetic gene cluster termed the pks island. The increased prevalence of pks+ E. coli in CRC patients and the ability of pks+ strains to potentiate tumorigenesis in mouse models of CRC suggest colibactin may play a causal role in cancer progression. However, achieving a mechanistic understanding of colibactin's genotoxicity and contribution to CRC has been impeded by an inability to isolate and structurally characterize the active genotoxic metabolite(s). During the previous funding period of this grant, we gained critical information about colibactin's structure and mode of action by studying the enzymes involved in its biosynthesis. Most notably, we established that colibactin is a DNA alkylating agent and proposed a potential structure for the active genotoxin. The overall objective of this renewal application is to elucidate additional molecular mechanisms underlying colibactin's activity and role in CRC carcinogenesis. Building off of the central hypothesis that the genotoxic activity of colibactin derives from the formation of DNA interstrand cross-links (ICLs), our three specific aims will: 1) characterize the specificity and structure of colibactin-DNA ICLs; 2) develop small molecules that inhibit colibactin biosynthesis in microbial communities; 3) elucidate the physiological location and timing of colibactin-mediated DNA damage in CRC development. These advances will be enabled by our multidisciplinary approach, which merges knowledge and techniques from chemical biology, structural biology, microbiology, toxicology, and cancer biology. Overall, this effort will fill critical gaps in fundamental knowledge needed to elucidate the role of colibactin-producing gut bacteria in CRC carcinogenesis and ultimately impact cancer prevention, diagnosis, and treatment. Additionally, by successfully demonstrating that studying and manipulating individual disease-associated microbial pathways can provide key mechanistic insights, this work will also support and validate future efforts to understand how other gut microbial activities influence CRC initiation and development.

项目摘要 结直肠癌（CRC）是美国第三大流行的癌症形式，也是第二个主要原因 癌症死亡。在过去的几十年中，研究表明，肠道微生物群会影响CRC和 最近的工作已将肠道细菌基因毒素作为癌症发展和进展的关键效应子。 与癌症最密切相关的细菌基因毒素之一是哥尼伯蛋白，这是人类产生的代谢产物 肠道共生细菌，包括某些大肠杆菌菌株，具有生物合成基因簇称为 PKS岛。 CRC患者PK+大肠杆菌的患病率增加以及PK+菌株增强的能力 CRC小鼠模型中的肿瘤发生表明结肠癌可能在癌症进展中起因果作用。 然而，对科里列氏素的遗传毒性和对CRC的贡献有一种机械理解一直是 无法分离和结构表征活性遗传毒性代谢产物（S）的阻碍。在 这笔赠款的以前的资金期，我们获得了有关科里巴辛结构和模式的关键信息 通过研究涉及其生物合成的酶的作用。最值得注意的是，我们确定Colibactin是 DNA烷基化剂，并提出了活性基因毒素的潜在结构。总体目标 更新的应用是阐明科比氏素活性和作用的其他分子机制 CRC致癌。基于中心假设，即结肠癌的遗传毒性活性来自 DNA Interstrand交联的形成（ICL），我们的三个特定目的将：1）表征特异性 和结构性colibactin-DNA ICL的结构； 2）开发小分子，这些分子抑制了微生物中结肠癌的生物合成 社区； 3）阐明了CRC中结肠癌介导的DNA损伤的生理位置和时间 发展。这些进步将通过我们的多学科方法来实现，该方法将知识和 化学生物学，结构生物学，微生物学，毒理学和癌症生物学的技术。总体而言，这 努力将填补所需的基本知识的关键空白，以阐明产生结肠癌的肠道作用 CRC癌变中的细菌，最终影响癌症的预防，诊断和治疗。此外， 通过成功证明研究和操纵单个疾病相关的微生物途径 可以提供关键的机械见解，这项工作还将支持并验证未来的努力，以了解如何了解 其他肠道微生物活动会影响CRC的启动和开发。