FOLIC ACID METABOLISM AS A TARGET OF CHEMOTHERAPY

这项拟议中的项目是一项旨在 开发肿瘤疾病化疗的新方法。 这项研究的主要目标是设计新颖的面向目标的 基于生化和机械原理的抗叶酸，源于 结构和功能信息，并研究它们在 细胞和分子水平。作为具体目标，拟议的研究 重点关注两个相互关联的代谢周期的酶，其中一个负责 叶酸多聚γ-谷氨酸的形成和分解 和抗叶酸，另一种依赖叶基多谷氨酸 胸腺苷的生物合成(TS循环)。建议的研究集 具体目标如下：设计和合成潜力 叶基多谷氨酸合成酶、γ-谷氨酰水解酶的抑制剂 (共轭)、胸苷合成酶、二氢叶酸还原酶和丝氨酸 羟甲基转移酶；以评价这些抑制剂对 它们在细胞酶系统中的各自靶标；以确定 目标化合物对L1210小鼠和小鼠的生长抑制作用 CCRF-CEM培养的人白血病细胞；研究其作用机制 选定的抑制剂-酶在分子水平上的相互作用 酶学、X射线结晶学、分子力学和 计算机图形学；研究活性抗叶酸的多谷氨酰化 以及它对生物活性的重要性；将细胞和 无细胞酶抑制活性与体外细胞毒性数据 根据这些相关性选择体内生物学的候选者 测试。药物-酶相互作用的研究可能会加深我们的认识 叶酸依赖酶的机制，并提供了新的理论基础 用于抑制剂设计。因为叶酸新陈代谢与 核酸生物合成和细胞增殖，这项研究可能 导致在肿瘤生物学中的重要观察和新的方法 癌症治疗。

The proposed project is part of a long range research effort aimed at the development of new approaches to the chemotherapy of neoplastic diseases. The main objective of this research is to design novel target-oriented antifolates based on biochemical and mechanistic rationales derived from structural and functional information and to study their effects at the cellular and molecular level. As specific targets, the proposed study focuses on enzymes of two interrelated metabolic cycles, one responsible for the formation and breakdown of the poly-gamma-glutamates of folates and antifolates and the other the folylpolyglutamate dependent biosynthesis of thymidylate (the TS cycle). The proposed research sets the following specific aims: To design and synthesize potential inhibitors of folylpolyglutamate synthetase, gamma-glutamyl hydrolase (conjugase), thymidylate synthase, dihydrofolate reductase and serine hydroxymethyl transferase; to evaluate the effects of the inhibitors on their respective targets in cellular enzyme systems; to determine the growth inhibitory effects of the target compounds on L1210 mouse and CCRF-CEM human leukemia cells in culture; to study the mechanism of selected inhibitor-enzyme interactions at the molecular level using techniques of enzymology, X-ray crystallography, molecular mechanics and computer graphics; to study the polyglutamylation of active antifolates and its importance for biological activity; to correlate cellular and cell-free enzyme inhibitory activity with in vitro cytotoxicity data and based on these correlations select candidates for in vivo biological testing. The study of drug-enzyme interactions may further our knowledge of the mechanisms of folate dependent enzymes and furnish new rationales for inhibitor design. Since folate metabolism is intimately linked to nucleic acid biosynthesis and cellular proliferation, this research may lead to important observations in tumor biology and new approaches to cancer treatment.