Novel Aureolic Acid-Type Antitumor Agents

描述（由申请人提供）：金果酸类抗癌药物，如米霉素（MTM）或色霉素（CMM），是具有独特作用方式的强效抗癌药物。它们通过交联富含gc的DNA来抑制癌细胞的生长，从而关闭特异性蛋白（Sp）依赖于各种原癌基因的途径，包括c-myc和c-src，后者与这些药物中发现的独特的低钙活性有关。其中MTM尤为重要，已成为研究sp依赖性信号转导途径的热门生化工具，但由于其毒副作用，除用于治疗其他化疗难以治疗的肿瘤高钙血症外，很少用作抗癌药物。然而，MTM最近被确定为治疗神经系统疾病、关节炎和血液系统疾病的潜在先导药物。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之前的资助期内得到了深入的研究，因此进行了组合生物合成的努力，揭示了各种生物合成中间体和新的MTM类似物。其中两种类似物，MTM SK和MTM SDK，显示出比MTM本身更好的抗癌活性，治疗指数大大提高。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有趣的关键酶，特别是加氧酶MtmOIV、酮还原酶MtmW、糖基转移酶MtmGIV、MtmGIII、MtmGII、MtmGI等早期作用的后聚酮合酶裁剪加氧酶和还原酶。目的是了解这些酶在MTM生物合成中的作用和机制，并优化它们用于新型MTM衍生物的工程设计。计划(a)进一步研究尚不清楚的MTM和CMM途径的生物合成步骤和机制，并利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)研究和提高糖基转移酶的底物特异性，(d)研究体外和体内MTM SK， MTM SDK和其他有前途的MTM类似物在项目中开发。

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.