BIO-ENGINEERING OF COMPOUNDS ACTIVE AGAINST MDR CANCER

有效对抗耐多药癌症的化合物的生物工程

• 批准号: 6260415
• 负责人: Nigel D PRIESTLEY
• 金额: $ 7.91万
• 依托单位: UNIVERSITY OF MONTANA
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-04-01 至 2003-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6260415
• 关键词: P glycoprotein; Streptomyces; antineoplastic antibiotics; drug design /synthesis /production; macrolide antibiotics; microorganism metabolism; multidrug resistance

DESCRIPTION: Nonactin is an inhibitor of the 170-kDa-P-glycoprotein mediated efflux of 4'-O-tetrahydropyranyladriamycin in multi-drug resistant erythroleukemia K562 cells. Nonactin and its macrotetrolide homologues are als active against cancer cell lines in vitro and have shown tumor reducing activity in in vivo studies with mice. Further, the macrotetrolides act as typical ionophore antibiotics being effective against Gram+ bacteria, fungi, and mycobacteria. Nonactin is not a current drug candidate because of its relatively high toxicity. The naturally occurring homologues, however, have greater activity than nonactin: from a QSAR analysis we propose a series of ne compounds which have potentially much higher activity. Chemical synthesis of macrotetrolide homologues is not trivial as it requires the separate synthesis of both enantiomers of nonactic acid; selective assembl of nonactic acid units into a tetrameric intermediate; and finally a macrolactonization reaction to form the macrotetrolide ring. Streptomyces griseus strain ETH A7796, in comparison, can readily make over 1 gL-1 of nonactin in fermentation. We propose to combine the best aspects of chemical synthesis and 'biosynthesis' to make new macrotetrolides. Chemical synthesis will be used to make racemic nonactic acid analogs via established, efficient routes. 'Biosynthesis' in a genetically altered strain of S. griseus will achieve the stereospecific biotransformation of the nonactic acid analogs into new macrotetrolides. The specific aims of this proposal are: 1. To purify from S. griseus ETH A7796 and characterize the key enzyme in nonactin biosynthesis, nonactate synthase, which catalyzes the conversion of a acyclic precursor into nonactic acid. 2. To isolate and characterize genes of the nonactin biosynthesis cluster. 3. To use a mutant strain, disrupted in nonactin biosynthesis, to make four prototypical macrotetrolide analogs, and to study their physical and biologica properties.

描述：Nonactin 是 170-kDa-P-糖蛋白的抑制剂 多重耐药中 4'-O-四氢吡喃霉素介导的外流 红白血病K562细胞。 Nonactin 及其大环四内酯同系物是 在体外对癌细胞系具有活性，并显示出肿瘤减少 小鼠体内研究的活性。 此外，大环四内酯充当 典型的离子载体抗生素对革兰氏+细菌、真菌、 和分枝杆菌。 Nonactin 不是当前的候选药物，因为它 毒性相对较高。 然而，天然存在的同系物 比 nonactin 具有更强的活性：根据 QSAR 分析，我们提出了一系列 具有潜在更高活性的新化合物。 大环四内酯同系物的化学合成并不简单，因为它 需要单独合成九乙酸的两种对映体； 将九乙酸单元选择性组装成四聚体中间体；和 最后进行大环内酯化反应，形成大环四内酯环。 相比之下，灰色链霉菌菌株 ETH A7796 可以轻松改造 发酵中的 1 gL-1 nonactin。 我们建议结合最好的方面 化学合成和“生物合成”来制造新的大环四内酯。 化学合成将用于通过以下方式制备外消旋非乳酸类似物 既定的、高效的路线。 基因改造中的“生物合成” S. griseus 菌株将实现立体特异性生物转化 将非乳酸类似物转化为新的大环四内酯。 该提案的具体目标是： 1. 从 S. griseus ETH A7796 中纯化并表征其中的关键酶 nonactin 生物合成，nonactate 合成酶，催化转化 形成壬酸的无环前体。 2. 分离和表征nonactin生物合成簇的基因。 3. 使用非肌动蛋白生物合成被破坏的突变菌株来制造四种 原型大环四内酯类似物，并研究它们的物理和 生物学特性。