NOVEL AUREOLIC ACID TYPE ANTITUMOR AGENTS

性状：（由申请人提供）：光神霉素（MTM）是一种金油酸 由各种链霉菌产生的抗微生物和抗肿瘤剂 包括S.已被使用，例如，用于治疗 睾丸癌此外，MTM在抗癌剂中是独特的， 它也被临床用于治疗癌症引起的恶性肿瘤， 高钙血症和佩吉特骨病。然而，MTM的骨髓，肝脏， 和肾毒性限制了其广泛的临床应用。提出要 研究抗肿瘤药物生物合成的各个方面， 破骨细胞抑制剂光神霉素，以开发类似物， 增加的治疗指数，这也可以使两者分离 MTM的主要作用，（i）对癌症生长和（ii）对破骨细胞。这 将产生新的抗肿瘤剂和/或抗骨质疏松症的治疗剂 以及其他与骨骼生长障碍有关的疾病， 为将来新的基因治疗概念。组合生物合成方法 将用于提供MTM类似物的阵列。为此，生物合成 MTM途径，其由II型聚酮合酶（PKS）主导， 需要进一步的鉴定。尤其是编码酶的基因 负责后期生物合成步骤，后PKS剪裁酶， 特别是氧化还原酶和基团转移酶将被修饰 突变菌株将有助于确定一系列事件中的 生物合成途径，并将表征底物和功能的重要 MTM途径中的酶。这些信息将用于设计新颖的 具有特定活性增加功能的化合物。的上下文中 MTM对破骨细胞的作用机制，我们想探讨MTM是否 衍生物可以影响c-src的表达，c-src是一种原癌基因， 破骨细胞骨吸收，遵循MTM和MTM的新假设 它的衍生物通过阻断Sp1与 c-src原癌基因的启动子区。 将处理以下三个具体目标： (1)为了进一步表征光辉霉素的生物合成途径， 通过选择性基因失活开发新的尼特拉霉素衍生物， 产品标识各种基团转移酶和氧化还原酶将被 研究了此外，mtm基因将与有希望的 脱氧糖生物合成、糖基转移酶和加氧酶编码基因， 开发新的在其结构中修饰的尼特拉霉素类似物的其它途径 糖和/或0原子模式。 (2)MTM途径的两种加氧酶MtmOII和MtmOIV将被 研究了对MtmOII（一种早期作用的加氧酶）的研究将有助于 确定最终PKS产品之间的缺失环节， 4-去甲基普瑞红霉素酮，最早的光神霉素前体记录， 约会四环红霉素类似物将被转化为它们的三环霉素类似物。 并通过在细胞中过表达加氧酶MtmOIV， 各种糖基转移酶缺失突变体。 (3)为了测定MTM及其新型类似物与富含GC的 c-myc和c-src启动子中的元件及其阻止Sp1的能力 约束力测试高亲和力c-myc将遵循这一点和c-src的结合 用于抑制人癌细胞中基因表达的化合物及其用途 对正常细胞和癌细胞的生长和活力的影响。最后，有希望 将分析c-src抑制类似物的活性， 破骨细胞介导的骨吸收。

DESCRIPTION: (provided by applicant):Mithramycin (MTM) is an aureolic acid antimicrobial and antitumor agent produced by various Streptomyces species including S. argillaceus, which has been used, e.g., for the treatment of testicular carcinoma. In addition, MTM is unique among anticancer agents in that it also has been used clinically to treat cancer-caused malignant hypercalcemia and Paget's bone disease. However, MTM's bone marrow, hepatic, and renal toxicity limit its widespread clinical use. It is proposed to investigate various aspects of the biosynthesis of the antitumor and osteoclast-inhibiting agent mithramycin in order to develop analogs with increased therapeutic indices, which also may allow the separation of the two principal effects of MTM, (i) on cancer growth and (ii) on osteoclasts. This will lead to novel antitumor agents and/or to therapeutics against osteoporosis and other diseases related to bone growth disorders, and bears the potential for a novel gene therapy concept in future. Combinatorial biosynthetic methods will be used to provide an array of MTM analogs. For this, the biosynthetic pathway to MTM, which is dominated by a type II polyketide synthase (PKS), needs to be further characterized. Especially genes encoding enzymes responsible for the late biosynthetic steps, the post-PKS tailoring enzymes, particularly oxidoreductases and group transferases will be modified Resulting mutant strains will help to determine the series of events within the biosynthetic pathway and will characterize substrates and function of important enzymes in the MTM pathway. This information will be used to design novel compounds with specific activity-increasing functionality. In context with the mechanism of action of MTM on osteoclasts, we want to explore whether MTM derivatives can effect the expression of c-src, a proto-oncogene necessary for the osteoclastic bone resorption, following the novel hypothesis that MTM and its derivatives inhibit osteoclast bone resorption by blocking Sp 1 binding to the promoter region of the c-src proto-oncogene. The following three specific aims will be addressed: (1) To further characterize the biosynthetic pathway of mithramycin and to develop new niithramycin derivatives through selective gene inactivation and product identification. Various group transferases and oxidoreductases will be investigated. In addition, the mtm genes will be recombined with promising deoxysugar biosynthesis, glycosyltransferase and oxygenase encoding genes from other pathways to develop novel niithramycin analogs modified in their saccharide and/or 0-atom pattern. (2) The two oxygenases of the MTM pathway, MtmOII and MtmOIV, will be investigated. The work on MtmOII, an early-acting oxygenase, will help to identify the missing link between the final PKS product and 4-demethylpremithramycinone, the earliest mithramycin precursor documented to date. Tetracyclic niithramycin analogs will be converted into their tricycic and expected more active counterparts by overexpressing oxygenase MtmOIV in the various glycosyltransferase deletion mutants. (3) To assay the binding properties of MTM and its novel analogs to the GC-rich elements in the c-myc and c-src promoters and their ability to prevent Sp 1 binding. Testing the high-affinity c-myc will follow thisand c-src binding compounds for inhibition of gene expression in human cancer cells and for their effects on growth and viability of normal and cancer cells. Finally, promising c-src inhibiting analogs will be analyzed for activity against osteoclastmediated bone resorption.