Anti-Tumorigenic Potential of Novel Digitoxin Analogues

描述(申请人提供)：洋地黄毒素作为癌症治疗药物的潜力已被广泛调查；然而，治疗指数较窄和潜在的毒副作用使其无法在临床环境中作为抗癌药物使用。这项研究的长期目标是利用组合合理的药物设计方法开发新的洋地黄毒素类似物，与现有的心脏糖苷相比具有更强的抗肺癌活性，但副作用更低。这项研究与NHLBI的任务直接相关。这些类似物将使用发散的从头合成钯催化的碳水化合物合成方法生成，并使用体外、体外和电子技术进行测试。此外，重要的凋亡和血管生成介体，对洋地黄毒素及其类似物在肺癌中的抗肿瘤作用至关重要，将被描述。AIM I的设计目的是 研究已确定的一种新的洋地黄毒素单糖类似物(Monod)诱导的强大的细胞凋亡效应，确定其促凋亡作用的关键细胞内调节因子，并描述介导Monod和洋地黄毒素对肺癌细胞作用的自由基的作用。初步数据清楚地表明，使用钯催化方法合成的莫诺德在NCI的60个癌细胞系上显示出比洋地黄毒素高五倍以上的细胞毒活性，并且对NSCLC细胞系特别有效。此外，DAT显示Monod的抗增殖作用可能是通过调节bcl2和caspase介导的，这将在这里进行评估。在AIM II中，将研究Monod和洋地黄毒素的肿瘤血管抑制潜力，潜在的作用机制，以及自由基的作用。 初步数据显示，Monod具有强大的抗血管生成潜力，并抑制了关键的血管生成介质Akt和HIF1�，这一点得到了支持。这一目标的目标将使用体外和体外技术来实现，并将研究凋亡(Bcl2)和血管生成(hif1�，血管内皮生长因子)通路之间的潜在串扰。为了进一步提高莫诺德和洋地黄毒素的有效性和特异性，并为这些药物寻找新的结合底物，在AIM III中提出了一种合理的药物设计方法。与传统的SAR技术、同源建模和对接不同，电子计算机技术将采用更快、更高效的技术。此外，结合研究将用于确定Monod和洋地黄毒素的新结合底物。在确定合适的潜在药物衍生物洋地黄和莫诺德后，将使用固有的灵活的从头方法来合成新的候选药物。这些药物将使用AIM I和AIM II中的技术验证其作用的特异性，并通过测量增殖、迁移、侵袭和肿瘤转移来验证其抗肿瘤活性。这项研究不仅对于了解心苷在肺癌细胞中的作用模式很重要，而且对于产生一类新的药物也很重要，这些药物可能针对多种对肿瘤进展至关重要的新途径，因此可能被证明对各种癌症有效。

DESCRIPTION (provided by applicant): The potential of digitoxin as a cancer therapeutic has been extensively investigated; however a narrow therapeutic index and potential for toxic side effects have precluded its use in clinical settings as an anti-cancer agent. The long-term goal of this study is to develop, using a combinatorial rational drug-design approach, novel analogues of digitoxin that possess enhanced anti-tumor activity against lung cancer as compared to existing cardiac glycosides but with lower side effects. This study is directly relevant to the mission of the NHLBI. These analogues will be generated using a divergent de novo palladium-catalyzed carbohydrate synthesis methodology and tested using in vitro, ex vivo and in silico techniques. Further, important apoptotic and angiogenic mediators that are critical to the anti-tumor effect of digitoxin and its analogues in lung cancer will be delineated. Aim I is designed to characterize the potent apoptotic effect induced by an already identified novel monosaccharide analogue of digitoxin (MonoD), identify key intracellular regulators of its pro-apoptotic effect, ad delineate the role of free radicals that mediate MonoD and digitoxin action on lung cancer cells. Preliminary data clearly indicates that MonoD, synthesized using the palladium-catalyzed approach, demonstrates more than five-fold higher cytotoxic activity than digitoxin on NCI's panel of sixty cancer cell lines, and is particularly potent against NSCLC cell lines. Further, dat shows that the anti- proliferative effects of MonoD may be mediated by modulation of Bcl2 and caspases, which will be evaluated here. In Aim II, the tumor-angiostatic potential of MonoD and digitoxin, the underlying mechanisms of action, and the role of free radicals will be investigated. This is supported by preliminary data showing potent anti- angiogenic potential for MonoD, and inhibition of the key angiogenic mediators Akt and HIF1�. The objectives of this aim will be achieved using both in vitro and ex vivo techniques, and potential cross-talk between the apoptotic (Bcl2) and angiogenic (HIF1�, VEGF) pathways will be investigated. To further improve upon the efficacy and specificity of MonoD and digitoxin and identify novel biding substrates for these drugs, a rational drug-design approach is proposed in Aim III. As opposed to traditional SAR techniques, homology modeling and docking, in silico techniques that are quicker and more efficient will be employed. In addition, binding studies will be used to identify novel binding substrates for MonoD and digitoxin. Upon identification of suitable potential drug derivatives of digitoxin and MonoD, the inherently flexible de novo methodology will be used to synthesize the new candidate drugs. These drugs will be validated for specificity of action using techniques in Aim I and Aim II, and validated for anti-tumor activity by measuring proliferation, migration, invasion and tumor-metastasis. This study is important not only for the understanding of the mode of action of cardiac glycosides in lung cancer cells, but also to generate a new class of drugs that may target multiple novel pathways critical to tumor progression, and thus may prove to be effective across a variety of cancers.