Novel Aureolic Acid-Type Antitumor Agents

说明书(申请人提供)：金酸类抗癌药物，如米曲霉素(MTM)或色霉素(CMM)，是具有独特作用模式的强效抗癌药物。它们通过连接富含GC的DNA来抑制癌细胞的生长，从而关闭依赖于特异性蛋白(Sp)的通路，从而通向包括c-myc和c-src在内的各种原癌基因，后者与这些药物独特的降钙活性有关。尤其是MTM非常重要，已成为研究Sp依赖的信号转导途径的常用生化工具，但由于其毒副作用，除了用于治疗其他化疗药物耐药的肿瘤高钙血症外，很少被用作抗癌药物。然而，MTM最近被确定为治疗神经系统疾病、关节炎和血液病的潜在先导药物。所有这些新的应用只需要非常小的、毒性较低的药物浓度，尽管在这些情况下的作用模式仍然不清楚。MTM的生物合成在本研究项目的前一个资助期内得到了深入的研究，因此进行了组合生物合成努力，发现了各种生物合成中间体和新的MTM类似物。其中两个类似物，MTM SK和MTM SDK，显示出比MTM本身更好的抗癌活性和显著改善的治疗指数。这些新药值得进一步研究。在以往的生物合成研究中，发现了一些耐人寻味的关键酶，特别是加氧酶MtmOIV、酮还原酶MtmW、糖基转移酶MtmGIV、MtmGIII、MtmGII、MtmGI，以及其他一些早期作用的后多酮合成酶，这些酶都是为加氧酶和还原酶量身定制的。目的是了解这些酶在MTM生物合成中的作用和机制，并对它们进行优化，以用于新型MTM衍生物的工程设计。计划(A)进一步研究MTM和CMM途径的生物合成步骤和机制，并应用组合生物合成产生新的MTM类似物；(B)分析有趣的加氧酶和还原酶；(C)研究和改进糖基转移酶的底物专一性；(D)在体外和体内研究MTM SK、MTM SDK和在该项目期间开发的其他有希望的MTM类似物。 与公共健康相关：拟议的工作旨在开发和提炼毒性显著降低的新一代金棕榈酸型天然产品类似物，这些类似物将主要用作抗癌药物，但也用作治疗神经疾病、关节炎和血液病的药物。为了能够通过组合生物合成来生产这些微调药物，将深入研究包括关键酶在内的生物合成机制。

DESCRIPTION (provided by applicant): Aureolic acid-type anticancer agents, such as mithramycin (MTM) or chromomycin (CMM), are potent anticancer drugs with a unique mode-of-action. They inhibit the growth of cancer cells by cross-linking GC-rich DNA thereby shutting down specificity-protein (Sp)-dependent pathways towards various proto-oncogenes including c-myc and c-src, the latter being associated with the unique hypocalcemic activity found for these drugs. Particularly, MTM is important, and has become a popular biochemical tool to study Sp-dependent signal transduction pathways, but due to its toxic side effects is rarely used as anticancer agent, except for the treatment of tumor hypercalcemia refractory to other chemotherapy. However, MTM was recently identified as a potential lead drug against neurological diseases, arthritis, and for the treatment of hematologic disorders. All these new applications require only very small, less toxic concentrations of the drug, although the mode-of- action in these contexts remains obscure. MTM's biosynthesis has been studied intensely during the previous funding period of this research project, and consequently pursued combinatorial biosynthetic efforts revealed various biosynthetic intermediates and new MTM-analogues. Two of these analogues, MTM SK and MTM SDK, showed a much better anticancer activity profile with a greatly improved therapeutic index than MTM itself. These new drugs deserve further investigations. During the previous biosynthetic studies biosynthetic intriguing and interesting key enzymes were discovered, which need to be further investigated, particularly oxygenase MtmOIV, Ketoreductase MtmW, glycosyltransferases MtmGIV, MtmGIII, MtmGII, MtmGI, and other, early acting post-polyketide synthase tailoring oxygenases and reductases. The goal is to understand the role and mechanisms of these enzymes in the MTM biosynthesis, and to optimize them for the engineering of novel MTM derivatives. It is planned to (a) further investigate unclear biosynthetic steps and mechanisms of the MTM and CMM pathways and to generate new MTM analogues applying combinatorial biosynthesis, (b) to analyze intriguing oxygenases and reductases, (c) to investigate and improve the substrate specificity of glycosyltransferases, (d) to study in vitro and in vivo MTM SK, MTM SDK and other promising MTM analogues developed during the project. PUBLIC HEALTH RELEVANCE: The proposed work aims to develop and refine a new generation of aureolic acid type natural product analogues with significantly diminished toxicity that will be useful mainly as anticancer drugs, but also as drugs to treat neurological diseases, arthritis and hematologic disorders. To enable the production of these fine-tuned drugs through combinatorial biosynthesis, in-depth research of the biosynthetic machinery including key enzymes will be explored.