Developing synergistic therapeutic strategies targeting deregulated nucleotide metabolism in MYC-driven lymphomas

项目摘要 这个项目试图描绘PRPS2(磷酸核糖焦磷酸合成酶)LOF 导致c-Myc过表达的淋巴瘤的选择性代谢易感性。的异构体 磷酸核糖焦磷酸合成酶(PRPS1和PRPS2)是从头开始的限速步骤 核苷酸生物合成，因为它们是负责产生5-磷酸核糖-1- 焦磷酸(PRPP)-包括ATP、GTP和IMP在内的所有核苷酸的必要成分。为了 满足c-myc过度表达细胞对合成代谢细胞成分的需求，它们必须能够 核苷池增加。这为利用增加的核苷酸水平提供了一个机会之窗 C-myc高表达B细胞的生物合成作为癌症治疗的一种手段，因此 本研究为磷酸核糖焦磷酸合成酶。最近的研究发现 通过PRPS2功能丧失(LOF)抑制核苷酸生物合成诱导显著的细胞凋亡 伯基特淋巴瘤细胞的一部分。阐明PRPS2 LOF Will显示的代谢易损性 告知社区PRPS2满足了哪些特定的生物需求，并支持新的 以核苷酸生物合成为目标的组合疗法的策略。考虑到生成的初步数据 我们的实验室已经知道，PRPS2 LOF的细胞死亡是细胞固有的，而PRPS1的选择性丢失不是 导致细胞凋亡反应的激活。这一结果在体外和体内模型中保持一致。 并为进一步研究利用这种诱导合成致死性的方法提供了基础。最关键的 这项建议的目的是：1)确定某些Myc过表达淋巴瘤的机制 细胞逃避PRPS2 LOF诱导的细胞凋亡和2)探索是否以及如何抑制核苷酸生物合成 使MYC过度表达的恶性肿瘤对靶向核苷酸生物合成或核苷的治疗药物敏感 经济舱。我们假设PRPS2 LOF产生一种合成致命性，可以与 药物基因组学方法针对从头开始/挽救核苷酸生物合成途径诱导 选择性和完全细胞死亡，并将通过使用标准剂量反应分析这一目标 曲线、细胞活力分析和代谢流体学来确定腺苷的摄取、速率和利用 通过关键的代谢途径和细胞活性分析来确定 补充。其次，我们将确定PRPS2 LOF的程度，因此会受到抑制 核苷酸生物合成，与现有治疗相结合以消除Eμ-Myc小鼠的淋巴肿大 模特。

Project Summary This project seeks to delineate the way in which PRPS2 (phosphoribosyl pyrophosphate synthetase) LOF results in selective, metabolic vulnerabilities in lymphoma with c-Myc overexpression. The isoforms of phosphoribosyl pyrophosphate synthetase (PRPS1 and PRPS2) are the rate limiting step in de novo nucleotide bio-synthesis as they are the enzymes responsible for the creation of 5-phosphoribosyl-1- pyrophosphate (PRPP) - a necessary component of all nucleotides including ATP, GTP, and IMP. In order to meet c-myc over-expressing cells’ demands for anabolic cellular components, they must have access to increased nucleoside pools. This provides a window of opportunity to use the increased levels of nucleotide bio-synthesis in B-cells with c-myc over-expression as a means of cancer therapy and therefore the focus of this investigation is the phosphoribosyl pyrophosphate synthetase enzyme. Recent studies have found inhibition of nucleotide bio-synthesis via loss of function (LOF) of PRPS2 induces apoptosis in a significant portion of Burkitt’s lymphoma cells. Elucidating the metabolic vulnerabilities demonstrated by PRPS2 LOF will inform the community as to what particular biological need is served by PRPS2 as well as underpin new strategies for combinatorial therapies that target nucleotide biosynthesis. Given the preliminary data generated by our lab, it is known that cell death upon PRPS2 LOF is cell intrinsic and selective- loss of PRPS1 does not result in activation of the apoptotic response. This result has remained consistent in in vitro and in vivo models and provides the basis for further study into ways to exploit this induced synthetic lethality. The most critical objectives of this proposal are to 1) Determine the mechanism by which some Myc overexpressing lymphoma cells evade PRPS2 LOF induced apoptosis and 2) Explore if and how dampened nucleotide biosynthesis sensitizes MYC over expressing malignancies to therapeutics that target nucleotide biosynthesis or nucleoside economy. We hypothesize that PRPS2 LOF produces a synthetic lethality that can be combined with pharmacogenomics approaches targeting de novo/ salvage nucleotide bio-synthetic pathways to induce selective and complete cell death and will analyze this objective through the use of standard dose response curves, cellular viability assays and metabolic fluxomics to determine uptake, rate, and utilization of adenosine through key metabolic pathways, and cellular viability assays to determine the degree of rescue achieved by supplementation. Second, we will determine to what extent does PRPS2 LOF, and therefore dampened nucleotide biosynthesis, combine with existing therapies to ablate lymphomagenesis in the Eμ- Myc mouse model.