Mucosal Cell Transporters and Enzymes in Drug Delivery

描述(由申请人提供)：该项目的长期目标是开发一种分子、机械的药物靶向方法。这项研究的中心假设是：前药可以靶向细胞过度表达转运蛋白和/或激活(水解酶)，以达到增强治疗效果的目的。该方法利用基因组学、蛋白质组学及其各自的数据库领域的快速发展的知识，将极大地促进识别膜转运体和激活负责前药运输和激活的酶。这项建议的具体目标是： 1：合成一系列脂肪族、芳香族、酸性、碱性亚氨基、酸性和碱性氨基酸类多肽前体药物氟尿苷、吉西他滨和依拉曲滨。 2：体外评价前药的溶液及酶解、转运活性和细胞生长抑制活性。 3：表征BPHL与抗癌前药的底物特异性，并与同源模型相关联，生产结构研究所需的量的酶，并确定癌细胞中其他前药激活酶的存在和特性。 4：与肿瘤细胞系中参与转运和激活所选前体药物的转运体和酶的表达水平相关，并与测量的转运、前体药物激活和肿瘤生长抑制活性相关。 在体内评估每种母药的两个前药候选药物的靶向潜力和与体外活性的相关性。这项建议将利用hPEPT1(和其他转运体)对核苷类似物前药的广泛特异性，以及我们最近发现的一种非常令人兴奋的酶--万乃洛韦水解酶(BPHL)，它可以激活前药万乃环韦和万乃昔洛韦。我们将基于这些发现开发和应用一种分子机制的药物靶向方法，并在体内用已知抗癌药物的前药测试这一策略。这些研究将为抗癌前药的靶向开发分子机制方法。本项目中开发的靶向途径和方法以及结构-活性相关性将广泛适用于为其他疾病状态制定靶向战略，并将在优化药物发现和开发过程中具有巨大价值。

DESCRIPTION (provided by applicant): The long-term goal of this project is to develop a molecular, mechanistic approach to drug targeting. The central hypothesis of this research is: Prodrugs can be targeted to cells over expressing transporters and/or activating (hydrolytic) enzymes to achieve enhanced therapeutic efficacy. The approach utilizes the rapidly advancing knowledge in the areas of genomics, proteomics, and their respective databases, that will greatly facilitate the identification of membrane transporters and activating enzymes responsible for transport and activation of prodrugs. The specific aims of this proposal are: 1: Synthesize a range of aliphatic, aromatic, acidic, basic imino, acidic, and basic, amino acid peptidomimetic prodrugs of floxuridine, gemcitabine and eladribine. 2: Evaluate the prodrugs in vitro for their solution and enzymatic hydrolysis, transport activity and cell growth inhibition activity. 3: Characterize the substrate specificity of BPHL with anticancer prodrugs and correlate with a homology model, produce the enzyme in amounts necessary for structural studies and determine the presence and identity of other prodrug activating enzymes from cancer cells. 4: Correlate the expression levels of transporters and enzymes involved in transport and activation of selected prodrugs in cancer cell lines and correlate with measured transport, prodrug activation and tumor growth inhibition activity. Evaluate two prodrug candidates in vivo for each parent drug for targeting potential and correlation with in vitro activity. This proposal will take advantage of the broad specificity of hPEPT1 (and other transporters) for nucleoside analogue prodrugs, and of our very exciting recent finding of an enzyme, valacyclovir hydrolase (BPHL), that activates the prodrugs valcyclovir and valganciclovir. We will develop and apply a molecular mechanistic approach to drug targeting, based on these findings and test this strategy in vivo with prodrugs of known anticancer agents. These studies will develop molecular mechanistic approaches for targeting anticancer prodrugs. The targeting approach and methods as well as structure-activity correlations developed in this project will be broadly applicable to the development of targeting strategies for other disease states and would be of immense value in optimizing drug discovery and development processes.