Targeted Proapoptotic Anticancer Drug Delivery System

描述（由申请人提供）： 在美国，卵巢癌是妇科恶性肿瘤中死亡的主要原因。结节性和漂浮性肿瘤集落不能通过手术充分治疗，需要广泛的化疗。化疗的成功取决于抗癌药物细胞耐药性的抑制和通常限制治疗的不良药物副作用的预防。该研究的长期目标是开发一种促凋亡靶向药物递送系统（DDS），以显着提高卵巢癌化疗的疗效。该研究的中心假设是，靶向促凋亡抗癌DDS将显著提高卵巢癌治疗的疗效，其方法是将抗癌药物特异性靶向卵巢癌细胞，同时诱导程序性细胞死亡和抑制主要的抗凋亡细胞防御机制。我们的初步实验表明：（1）促黄体生成激素释放激素（LHRH）可用作靶向部分，将抗癌药物特异性地递送至卵巢癌细胞;（2）合成的BCL-2同源性3（BH 3）结构域肽有效抑制卵巢癌细胞的抗凋亡防御;（3）BH 3和LHRH与PEG载体的缀合物比非缀合形式增加了效力。这些令人兴奋的初步结果有力地表明了所提出的方法的可行性。本研究的主要目的是开发、合成、表征和评价一种新型四组分靶向促凋亡抗癌DDS，其包括聚乙二醇聚合物作为可渗透载体; LHRH肽作为细胞表面靶向部分;抗癌药物喜树碱（CPT）作为细胞死亡诱导剂和合成BH 3肽作为抗凋亡细胞防御抑制剂。因此，所提出的研究的具体目的是：（1）设计、合成和表征新型CPT-PEGLHRH-BH 3生物缀合物，其中（a）PEG载体和活性组分（BH 3，CPT）之间的“生物可降解”或“非生物可降解”键和（B）每个缀合物的药物和靶向部分拷贝数可变。(2)评价含有药物载体（PEG聚合物）、抗癌药物（CPT）、抗凋亡细胞防御抑制剂（BH 3肽）和靶向部分（LHRH肽）的新型药物递送系统在人敏感和多药耐药癌细胞中的药物和组分释放、细胞摄取和保留以及抗癌有效性（即细胞毒性、细胞凋亡诱导和信号传导途径）。(3)在已建立的动物模型中检查DDS的体内释放/稳定性、CPT的药代动力学、肿瘤和器官蓄积和分布以及选定的促凋亡靶向药物递送系统的抗肿瘤活性。拟议工作的结果将用于设计治疗各种癌症的新方法。拟议的研究将填补我们对生物缀合物递送到癌细胞中的机制的理解中的重要空白，从而能够开发新的双层分子靶向策略以提高癌症化疗的疗效。

DESCRIPTION (provided by applicant): Ovarian cancer is the leading cause of death among gynecological malignancies in the United States. Micronodular and floating tumor colonies cannot be adequately treated by surgery and require extensive chemotherapy. The success of chemotherapy depends on the suppression of anticancer drug cellular resistance and the prevention of adverse drug side effects that typically limit therapies. The LONG-TERM GOAL of the proposed research is to develop a proapoptotic targeted drug delivery system (DDS) that will significantly increase the efficacy of ovarian cancer chemotherapy. The CENTRAL HYPOTHESIS of the proposed research is that targeted proapoptotic anticancer DDSs will significantly increase the efficacy of ovarian cancer treatment by targeting the anticancer drug specifically to ovarian cancer cells with the simultaneous induction of programmed cell death and the suppression of the main antiapoptotic cellular defense mechanisms. Our preliminary experiments demonstrate that (1) luteinizing hormone-releasing hormone (LHRH) can be used as a targeting moiety to deliver an anticancer drug specifically to ovarian cancer cells; (2) synthetic BCL-2 homology 3 (BH3) domain peptide effectively suppresses antiapoptotic defense in ovarian cancer cells and (3) conjugation of BH3 and LHRH to a PEG carrier increased potency over the nonconjugated forms. These exciting preliminary results strongly indicate the feasibility of the proposed approach. The main objective of the proposed research is to develop, synthesize, characterize and evaluate a novel four component targeted proapoptotic anticancer DDS which includes a polyethylene glycol polymer as a permeable carrier; LHRH peptide as a cell surface targeting moiety; the anticancer drug camptothecin (CPT) as an inducer of cell death and synthetic BH3 peptide as a suppressor of antiapoptotic cellular defense. Therefore, the SPECIFIC AIMS of the proposed investigations are: (1) To design, synthesize and characterize novel CPT-PEGLHRH- BH3 bioconjugates with (a) "biodegradable" or "non-biodegradable" linkages between PEG carrier and the active components (BH3, CPT) and (b) variable numbers of drug and targeting moiety copies per conjugate. (2) To evaluate drug and component release, cellular uptake and retention, and anticancer effectiveness (i.e. cytotoxicity, apoptosis induction and signaling pathways) of novel drug delivery systems containing a drug carrier (PEG polymer), an anticancer drug (CPT), an inhibitor of antiapoptotic cellular defense (BH3 peptide) and a targeting moiety (LHRH peptide) in human sensitive and multidrug resistant cancer cells. (3) To examine the in vivo release/stability of the DDS, the pharmacokinetics, tumor and organ accumulation and distribution of CPT and the antitumor activity of selected proapoptotic targeted drug delivery systems in well-established animal models. The results of the proposed work will be used to design novel approaches for the treatment of various cancers. The proposed studies will fill important gaps in our understanding of the mechanisms of bioconjugate delivery into cancer cells enabling the development of new two-tier molecular targeting strategies to increase the efficacy of cancer chemotherapy.