Mechanistic Comparison of Cisplatin with Synthetic DNA Repair-Shielding Anticance

描述（由申请人提供）：拟议工作的目标是将我们最近关于顺铂抗肿瘤反应机制的实验发现转化为治疗顺铂耐药肿瘤的新化合物的开发。这项资助的早期工作发现了顺铂的三种新的潜在毒性机制：(1)其DNA加合物吸引蛋白质，其中一些在癌细胞中表达，从而阻断DNA修复；(2)其DNA加合物“劫持”特异性hmg结构域转录因子，使其远离启动子，导致某些基因的表达减少；(3)错配修复蛋白结合顺铂加合物，使细胞对药物敏感。基于上述发现，在目前的资助期内，我们已经开发了几种具有潜在新作用机制的新型抗癌候选药物-受顺铂启发的机制。这些化合物中的主要候选化合物E27a被设计为通过可能与治疗顺铂耐药卵巢癌相关的机制起作用。E27a是一种双功能DNA损伤剂，可以在DNA中产生与雌激素受体有高亲和力的损伤位点。我们对顺铂的研究揭示了E27a的设计原则，包括顺铂DNA加合物结合和隔离对肿瘤生长和生存重要的蛋白质的能力。这项建议有两个平行的目标。一个是进一步描述我们的新药E27a的细胞毒性和抗肿瘤作用的分子机制。二是比较其对卵巢癌的疗效与临床使用或临床候选的顺铂及相关化合物。该研究的具体目标是：(1)合成铂和E27a的分子变体和放射性标记类似物，作为结构-活性研究的工具；(2)对敏感和耐药卵巢癌细胞进行顺铂和顺铂同系物的细胞毒性比较研究；(3)确定雌激素受体表达与卵巢癌对E27a敏感性及卵巢癌对顺铂耐药的关系；(4)比较E27a与顺铂在人卵巢癌动物模型中的疗效。利用卵巢癌的传统和遗传动物模型以及相关细胞系，我们计划确定我们最近制造的分子在多大程度上发挥了我们预期的作用，并确定它们与癌症治疗的相关性。将使用传统（免疫化学、遗传）和最新（RNAi、加速器质谱）方法的结合。

DESCRIPTION (provided by applicant): The goal of the proposed work is to translate our recent experimental findings on the mechanisms of antitumor responses to cisplatin into the development of novel compounds to treat cisplatin-resistant tumors. Earlier work on this grant discovered three novel prospective mechanisms of toxicity for cisplatin: (1) its DNA adducts attract proteins, some of which are expressed in cancer cells, that block DNA repair; (2) its DNA adducts "hijack" specific HMG-domain transcription factors away from their promoters, resulting in diminished expression of certain genes; and (3) mismatch repair proteins bind cisplatin adducts and sensitize cells to the drug. Based on the aforementioned discoveries, in the current grant period, we have developed several novel anticancer candidates with potentially novel mechanisms of action - mechanisms inspired by cisplatin. The lead candidate among these compounds, E27a, was designed to act by mechanisms that may be relevant for the treatment of cisplatin-resistant ovarian cancers. E27a is a bifunctional DNA damaging agent that can create damaged sites in DNA that have high affinity for the estrogen receptor. Principles incorporated into the design of E27a that were uncovered by our investigations of cisplatin include the ability of cisplatin DNA adducts to bind and sequester proteins important to tumor growth and survival. This proposal has two parallel objectives. One is to delineate further the molecular mechanisms responsible for the cytotoxic and antitumor effects of our new agent, E27a. The second is to compare its efficacy against ovarian cancers with that of cisplatin and related compounds that are in clinical use or are clinical candidates. The specific objectives of the proposed research are: (1) to synthesize molecular variants and radiolabeled analogs of platinum and E27a that are tools for structure-activity studies; (2) to perform comparative cytotoxicity studies against cisplatin and cisplatin homologues in sensitive and resistant ovarian cancer cells; (3) to determine the relationship between estrogen receptor expression and sensitivity of ovarian cancers to E27a and the resistance of those cancer cells to cisplatin; and (4) to compare the efficacy of E27a to that of cisplatin in animal models of human ovarian cancer. Using conventional and genetic animal models for ovarian cancer, and relevant cell lines, we plan to determine to what extent the molecules we have recently made work the mechanisms that we intended and to determine their relevance to cancer treatment. A combination of traditional (immunochemical, genetic) and recent (RNAi, accelerator mass spectrometry) methods will be used.