Chemical Glycobiology on Anthracyclines

描述(申请人提供)：蒽环类药物被认为是有史以来开发的最有效的抗癌药物之一，可以作为单一药物使用，也可以作为联合治疗使用。几种天然和半合成的蒽环类化合物被用作临床一线抗癌药物。柔红霉素(DNR)和伊达比星主要用于白血病和淋巴瘤，而阿霉素(DOX)和表阿霉素对白血病、淋巴瘤和各种实体肿瘤(包括乳腺癌、小细胞肺癌、宫颈癌和头颈癌)具有更广泛的抗癌活性。尽管在癌症治疗中得到了广泛的应用，但抗药性和心脏毒性是蒽环类药物的两大局限性。在过去的30年里，寻找新的蒽环类药物来克服这些限制从未停止过。 我们一直在系统地改变蒽环类药物碳水化合物部分的结构。最近，我们取得了重大突破：我们发现，通过简单地将柔红霉素中柔红素上的3‘-氨基(-NH2)转化为叠氮(-N3)基团，得到的3’-叠氮柔红霉素(ADNR)在小鼠体内既具有抗耐药肿瘤的活性，又具有较低的毒性。俄亥俄州立大学已经提交了一份专利申请，对一种临床上重要的药物进行这样一种看似简单但非常有效的修改。为了进一步提高ADNR的活性，我们将第二个2，6-二脱氧糖连接到ADNR中的第一个3‘-叠氮基柔豆胺上，所得到的二糖并环类化合物对蒽环类耐药癌细胞具有增强的作用，并对拓扑异构酶2(TOP2)和Top1靶标具有不同的选择性。所有这些观察结果促使我们对这一拟议的研究计划做出一个中心假设： 3‘-叠氮多柔比星(ADNR)或其类似物的药效团上的第二或第三糖的结构可以通过向DNA-拓扑异构酶-药物三元复合体提供一个基本的结合基序来增强蒽环类药物的活性和克服耐药性，而心脏毒性要低得多。 基于这一假设，提出了一种基于结构的方法来研究设计的蒽环类药物在DNA-药物复合体(如药物作用的第一步)和Top-DNA-药物复合体(如在下一步药物作用)中的相互作用和选择性。该计划将侧重于三个密切相关和协同的目标。 目的一、建立蒽环类药物的分子模拟和筛选平台。该平台由两个层次的建模组成。一个更简单的二元DNA-药物络合物模型将被用于初步筛选可能的二糖和三糖并环类化合物及其O-或N-取代类似物。核磁共振和X射线结晶学都将用于验证DNA-药物络合物模型。在下一个更具挑战性的水平上，将在TOP2-DNA-药物和Top1-DNA-药物复合体模型上进行分子建模和虚拟药物筛选。对这些模型的深入理解将在AIM III中用新的合成蒽环类药物和一系列生物和机械方法进行测试。 目的II.二糖或三糖蒽环类化合物的合成。不常见糖库的一个选择性子集将使用我们建立的收敛方法来合成。然后，将进一步开发化学和酶方法将这些不常见的糖转移到苷元以制备二糖和三糖并蒽环类化合物。 目的III.新合成的蒽环类化合物的生物学和机理研究。TOP2和Top1中毒的分子机制将在实验上阐明。该药物对耐药白血病和乳腺癌的活性将在体外和体内进行研究。心脏毒性和药代动力学将在异种移植小鼠模型上进行研究。 总而言之，该计划将首次将分子建模和实验验证相结合，开发一种设计碳水化合物修饰的蒽环类药物的新方法。这样的平台的成功将加速涉及DNA-酶-药物复合体的抗癌药物领域的新药发现。这项研究计划应该会产生新一代的临床前蒽环类药物候选药物。

DESCRIPTION (provided by applicant): Anthracyclines are considered to be some of the most effective anticancer drugs ever developed, either used as single agents or in combination therapy. Several natural and semi-synthetic anthracycline compounds are clinically used as the front-line anticancer drugs. Daunorubicin (DNR) and idarubicin are primarily used in leukemia and lymphoma, whereas doxorubicin (DOX) and epirubicin have broader anticancer activities against leukemia, lymphomas, and a variety of solid tumors including breast cancers, small cell lung cancers, cervical, as well as head and neck cancers. Despite the widespread use in cancer therapy, drug resistance and cardiotoxicity are the two major limitations for anthracycline drugs. Over the past 30 years, search for new anthracyclines to overcome these limitations has never ceased. We have been systematically altering the structure of the carbohydrate portion of anthracyclines. Recently, we made our major breakthrough: we discovered that by simply converting the 3'-amino group (-NH2) on daunosamine in daunorubicin into an azido (-N3) group with one organic transformation, the resulted 3'-azido daunorubicin (ADNR) confers both activity against drug-resistant cancers and much lower toxicity in mice. The Ohio State University has submitted a patent application for such a seemingly simple, but very effective modification of a clinically important drug. To further enhance the activity of ADNR, we connected a second 2,6-dideoxysugar to the first 3'-azido daunosamine in ADNR, the resulting disaccharide anthracyclines have an enhanced efficacy towards anthracycline-resistant cancer cells and different selectivity against topoisomerase 2 (Top2) and Top1 targets. All of these observations prompt us to make a central hypothesis for this proposed research program: The structures of the second or third sugar on the established pharmacophore of 3'-azidodaunorubicin (ADNR) or its analogs can enhance anthracycline activity and overcome drug resistance with much lower cardiac toxicity by presenting an essential binding motif to the DNA-topoisomerase-drug ternary complex. Based on this hypothesis, a structure-based approach is proposed to investigate interaction and selectivity of designed anthracyclines in DNA-drug complex (as in the first step of drug action) and in Top-DNA-drug complex (as in the next step of drug action). The program will focus on three closely related and synergistic aims. Aim I. Establishment of a platform for molecular modeling and screening of anthracycline drugs. The platform consists of two levels of modeling. A simpler binary DNA-drug complex model will be used for initial structural screening for a possible di- & trisaccharide anthracyclines and their O- or N-substituted analogs. Both NMR and X-ray crystallography will be used to validate the DNA-drug complex model. At the next more challenging level, molecular modeling and virtual drug screening will be performed on both Top2-DNA-drug and Top1-DNA-drug complex models. Insightful understanding from these models will be tested with new synthetic anthracyclines and with a series of biological and mechanistic approaches in Aim III. Aim II. Synthesis of di- or trisaccharide anthracyclines. A selective subset of an uncommon sugar library will be synthesized using our established convergent approaches. Then both chemical and enzymatic approaches will be further developed to transfer these uncommon sugars to aglycones for the preparation of di- & trisaccharide anthracyclines. Aim III. Biological and mechanistic investigation of the new synthetic anthracyclines. The molecular mechanisms of Top2 & Top1 poisoning will be clarified experimentally. Activities of the drug to drug-resistant leukemia and breast cancers will be investigated both in vitro & in vivo. Cardiac toxicity and pharmacokinetics will be studied on xenograft mice models. In summary, for the very first time, this program will combine molecular modeling and experimental validation to develop a new approach for designing carbohydrate-modified anthracyclines. The success of such a platform will accelerate new drug discovery in the field of anticancer drug involving DNA-enzyme-drug complex. This research program should produce new generations of preclinical anthracycline drug candidates.