Understanding methionine metabolism and its therapeutic potential in cancer

癌症患者的营养需求与健康患者不同。在这里， 以酶为靶点，从而以构成这些不同代谢的代谢网络为目标 需求正吸引着无数的药物开发努力。在靶向酶的同时 癌症特异性代谢途径已经成功，代谢是否会受到影响 在类似的程度上，通过特定和受控的方式进行营养控制在很大程度上 未知。蛋氨酸供应影响一碳循环通量、DNA和组蛋白甲基化 因此是表观遗传编程。膳食蛋氨酸限制(MR)也促进新陈代谢 健康和延长昆虫和哺乳动物的寿命，这两个抗癌功能。因此，我们 假设饮食MR可以抑制肿瘤生长并加强抗癌治疗。我们的 初步数据显示，饮食MR是一种经济有效的方法，可以改变血浆蛋氨酸 对健康的小鼠和人类都有效。MR调节有希望的肿瘤结果：在两个 RAS驱动的结直肠癌(CRC)患者来源的异种移植(PDX)模型，它推迟了肿瘤 生长并使肿瘤对5-氟尿嘧啶增敏，5-氟尿嘧啶是治疗结直肠癌的一线化疗药物； 自体KrasG12D+/-；TP53-/-软组织肉瘤模型 与辐射的协同效应。在这些模型中，半胱氨酸和蛋氨酸的代谢是 肿瘤和血浆中受影响最大的代谢途径。然而，分子 饮食MR与代谢相互作用并最终介导肿瘤的机制 结果还不得而知。为了探讨这些机制，我建议重点介绍CRC PDX模型 通过以下两个目标。在目标1中，我将首先使用最先进的代谢组学 本实验室建立的评价肿瘤和非肿瘤患者代谢改变的方法 肿瘤组织经饮食MR或MR和5-FU联合应用。在合并后 在体外发现，我将通过补充半胱氨酸或甜菜碱来进行饮食干预 确定蛋氨酸作为硫供体和一碳供体对肿瘤的贡献 分别在CRC PDX型号中实现增长。在目标2中，我将首先描述表观遗传学和 用亚硫酸氢盐测序、ATAC-DNA分析研究肿瘤和结直肠癌细胞对饮食MR的遗传适应性 序列、芯片序列和RNA序列。有了这些数据，我将构建一个代谢网络，并执行 应用CRISPR/Cas9技术筛选代谢途径基因。结果是 将揭示饮食MR介导的代谢、遗传和表观遗传机制 结直肠癌单纯抑瘤和联合5-FU治疗。预计它还将提供目标 代谢物和基因为未来假说的产生和新的癌症靶向治疗提供依据 新陈代谢。

Cancers have different nutritional requirements from their healthy counterparts. Herein, targeting the enzymes and thus the metabolic networks that constitute these different metabolic requirements is attracting numerous drug development efforts. While targeting enzymes in cancer-specific metabolic pathways has been successful, whether metabolism can be affected to similar extents by nutritional manipulation in specific and controlled manners is largely unknown. Methionine availability affects one-carbon cycle flux, DNA and histone methylation and thus epigenetic programming. Dietary methionine restriction (MR) also promotes metabolic health and extends insect and mammalian lifespan, two anti-cancer features. Thus, we hypothesize that dietary MR could inhibit tumor growth and enhance anti-cancer therapy. Our preliminary data show that dietary MR, a cost-effective approach, alters plasma methionine effectively in both healthy mice and humans. MR mediates promising tumor outcomes: in two RAS-driven colorectal cancer (CRC) patient-derived xenografts (PDX) models, it delays tumor growth and sensitizes tumor to 5-Fluorouracil, a frontline chemotherapy for CRC; and in an autochthonous KRASG12D+/-;TP53-/- soft tissue sarcoma model, it reaches a striking synergistic effect with radiation. In these models, cysteine and methionine metabolism is the most impacted metabolic pathway in the tumor and the plasma. However, the molecular mechanisms by which dietary MR interacts with metabolism and eventually mediates tumor outcome are unknown. To explore the mechanisms, I propose to focus on CRC PDX models through the following two aims. In Aim 1, I will first employ a state of the art metabolomics approach established in our laboratory to evaluate the metabolic alterations in tumor and non- tumor tissues by dietary MR or a combination of MR and 5-FU. Upon consolidation of the findings in vitro, I will conduct dietary interventions by supplementing cysteine or betaine to determine the contribution of methionine as a sulfur donor and a one-carbon donor to tumor growth in CRC PDX models, respectively. In Aim 2, I will first characterize the epigenetic and genetic adaptions to dietary MR in tumor and CRC cell linesusing bisulfite sequencing, ATAC- seq, ChIP-seq, and RNA-seq. With these data, I will construct a metabolic network and perform a functional screen of metabolic pathway genes using CRISPR/Cas9 technology. The outcome will reveal the metabolic, genetic, and epigenetic mechanisms underlying dietary MR-mediated tumor inhibition alone and in adjuvant with 5-FU in CRC. It is also anticipated to provide target metabolite and genes for future hypothesis generation and novel therapy targeting cancer metabolism.