Metabolism of cancer chemotherapeutics by the human gut microbiome

项目总结 来自我们实验室和其他实验室的严格数据表明，肠道微生物群可能是被低估的贡献者 癌症药物疗效和副作用的个体差异；然而，我们目前缺乏 来自临床前小鼠模型的机制洞察力和数据是为正在进行的癌症研究提供信息所必需的 病人。我们选择了包括5-氟尿嘧啶(5-FU)及其前体药物卡培他滨(CAP)在内的氟嘧啶类药物作为 最初的测试案例是由于它们在结直肠癌(CRC)治疗中的关键作用，增加口服给药， 高度多变的药代动力学，以及无法解释的疗效和毒性差异。我们提出了一系列 在体外和小鼠研究中，解剖了人类肠道细菌的种类、基因和酶，这些细菌与 5-FU(AIM 1)和CAP(AIM 2)的代谢及其对药物的下游影响 药代动力学(PK)和药效学(PD)。 我们的主要假设是氟嘧啶类药物的口服生物利用度和治疗效果 受不同人类肠道细菌物种编码的药物代谢途径的影响。 在目标1中，我们将鉴定和表征导致5-FU失活的主要肠道细菌分类群 通过生化和基于细胞的分析相结合的方法，结合诺生菌和异种移植的研究 老鼠模型。根据我们的初步结果，我们假设厌氧菌是主要的肠道 负责5-氟尿嘧啶代谢的个体间差异的细菌属。 在目标2中，我们试图发现负责将CAP激活为5-FU的细菌酶。 令人惊讶的发现是，大肠杆菌可以激活CAP，从而减少细菌在高温下的生长 浓度。我们假设，大肠杆菌催化了一个与哺乳动物相似的三步代谢途径 将CAP转化为5-FU。 我们在目标1中的结果将为剖析守恒性和冗余性提供有价值的原则证明 在临床相关微生物生物转化方面，帮助超越模型肠道细菌的研究 找出翻译上最相关的物种。目标2潜在地改变了范式，因为它将提供 CAP在肝细胞和癌细胞外被生物激活的确凿证据，创造了新的机会 改善治疗结果，研究这一代谢途径的生理作用和更广泛的影响。 总而言之，这项研究计划强调保护新陈代谢途径 跨生命领域的治疗学，强调需要区分人类和 微生物细胞对药物处置、疗效和副作用的影响。由于我们将重点放在目前使用的药物上 护理标准和人体肠道微生物群中普遍存在的自然产生的细菌物种，这 临床前研究计划具有明确的翻译相关性，并与正在进行的临床研究高度协同 我们团队和更广泛的微生物组领域对癌症患者进行的研究。

PROJECT SUMMARY Rigorous data from our lab and others indicate that the gut microbiome may an underappreciated contributor to inter-individual variations in cancer drug efficacy and side effect profiles; however, we currently lack the mechanistic insights and data from preclinical mouse models necessary to inform ongoing studies in cancer patients. We selected fluoropyrimidines, including 5-fluorouracil (5-FU) and its prodrug capecitabine (CAP), as an initial test case due to their critical role in colorectal cancer (CRC) therapy, increasing oral administration, highly variable pharmacokinetics, and unexplained differences in efficacy and toxicity. We propose a series of in vitro and mouse studies to dissect the human gut bacterial species, genes, and enzymes responsible for the metabolism of 5-FU (Aim 1) and CAP (Aim 2), including their downstream consequences for drug pharmacokinetics (PK) and pharmacodynamics (PD). Our overarching hypothesis is that the oral bioavailability and therapeutic effects of fluoropyrimidines are influenced by pathways for drug metabolism encoded by diverse human gut bacterial species. In Aim 1, we will identify and characterize the primary gut bacterial taxon responsible for 5-FU inactivation through a combination of biochemical and cell-based assays coupled to studies in gnotobiotic and xenograft mouse models. Based on our Preliminary Results, we hypothesize that Anaerostipes is the primary gut bacterial genus responsible for inter-individual variations in the metabolism of 5-FU. In Aim 2, we seek to discover the bacterial enzymes responsible for the activation of CAP to 5-FU, motivated by the surprising finding that E. coli can activate CAP leading to reduced bacterial growth at high concentrations. We hypothesize that E. coli catalyzes a 3-step metabolic pathway that mirrors the mammalian conversion of CAP to 5-FU. Our results in Aim 1 will provide a valuable proof-of-principle for dissecting the conservation and redundancies in clinically relevant microbial biotransformations, helping to move beyond studies of model gut bacteria to identify the most translationally relevant species. Aim 2 is potentially paradigm-shifting in that it would provide definitive evidence for CAP bioactivation outside of hepatocytes and cancer cells, creating new opportunities to improve treatment outcomes and study the physiological role and broader impacts of this metabolic pathway. Taken together, this research plan emphasizes the conservation of the pathways for metabolism of therapeutics across domains of life, highlighting the need to distinguish the relative contributions of human and microbial cells to drug disposition, efficacy, and side effect profiles. Due to our focus on drugs used as current standard of care and naturally occurring bacterial species prevalent in the human gut microbiome, this preclinical research program has clear translational relevance and is highly synergistic with ongoing clinical studies of cancer patients conducted by our team and the broader microbiome field.