CELL CYCLE TARGETS FOR ANTICANCER DRUGS

直到最近，细胞周期的蛋白质机制和病因学 人类癌症被认为是不同的主题。然而， 在鉴定驱动细胞凋亡的分子方面已经取得了进展， 并调节细胞循环引擎的活动。随着这一增长 在理解细胞分裂的基本过程中， 认识到细胞周期调节因子的紊乱可能对 在不受控制的生长和内在基因组中的作用 肿瘤细胞的不稳定性。细胞循环发动机的核心部件 是细胞周期蛋白及其相关的细胞周期蛋白依赖性激酶（CDK）。的 细胞周期研究的一个项目揭示了一系列酶， 作为开发新型抗癌药物的有前景的靶点。 该计划的总体目标是测试假设， 针对细胞周期机制特定成分的药物 将作为化疗剂有效治疗人 癌为这些药物发现选择的最初靶酶 研究的重点是cdc 25磷酸酶和细胞周期蛋白D相关蛋白。 激酶，CDK 4。细胞周期蛋白D-cdk 4复合物调节细胞周期的关键步骤， 细胞周期进程：G1期细胞进入S期的承诺。 阶段，并因此决定进行有丝分裂。与此相反， CDC 25磷酸酶在细胞周期的较晚时刻起作用， 活化有丝分裂CDC 2激酶的基本触发剂。使用 中国传统及其他药用植物，细菌及真菌 发酵液和基于天然产物的组合文库 作为新化学结构的来源，我们将致力于以下工作 具体目标：（1）实施基于多孔的筛选测定， CDC 25磷酸酶活性的抑制剂，和（2）开发和放置 在线高容量筛选蛋白激酶抑制剂 细胞周期蛋白D-cdk 4复合物的活性。已鉴定的这些抑制剂 细胞周期靶点将进行机械评价， 实验模型系统，并将进行测试， 临床相关的抗肿瘤活性的核心组成部分，我们的 药物发现小组 本核心的目标是从化合物中识别 在生物化学靶筛选中表现出活性的那些化合物 其对人肿瘤具有显著生长抑制活性 体外细胞 这些信息将用于确定 化合物需要化学修饰以提高细胞生物利用度 等等，以及哪些化合物被核心C用于体内测试。我们 将常规使用一组7种人类肿瘤细胞系，包括2种 乳腺癌、2例结肠癌、2例前列腺癌、1例卵巢癌和1例白血病细胞系。这 将使我们能够将药物活性与一组一般 难治性人实体瘤类型和一般响应性人 肿瘤类型（白血病）。 该小组包括人类实体肿瘤， 在Core C中作为异种移植物进行体内研究。我们也有可用的面板 低传代人原发性肿瘤细胞系，包括乳腺癌和 前列腺，以及被工程化以过表达感兴趣的靶点的细胞， 专门筛选。 将对铅进行药代动力学研究 化合物以帮助其临床前开发并提供信息 用于化学修饰以提高生物活性。

Until recently, the protein machinery of the cell cycle and the etiology of human cancer were considered separate topics. However, spectacular progress s been made in the identification of the molecules that drive and modulate the activity of the cell-cycle engine. With this increase in understanding of the fundamental process of cell division has come the realization that derangements in cell-cycle regulators may play crucial roles in both the uncontrolled growth and the intrinsic genomic instability of tumor cells. Central components of the cell-cycle engine are the cyclins and their associated cyclin-dependent kinases (cdks). The program in cell-cycle research has revealed a series of enzymes that serve as promising targets for the development of novel anticancer drugs. The overall objective of this program is to test the hypothesis that drugs targeted against specific components of the cell-cycle machinery will be effective as chemotherapeutic agents in the treatment of human cancer. The initial target enzymes selected for these drug discovery efforts are the cdc25 phosphatase and the cyclin D-associated protein kinase, cdk4. The cyclin D-cdk4 complex regulates a critical step in cell-cycle progression: the commitment of the G1-phase cell to enter S- phase, and, consequently, the decision to undergo mitosis. In contrast, the cdc25 phosphatase functions at a later point in the cell cycle as an essential trigger for the activation of the mitotic cdc2 kinase. Using Chinese traditional and other medicinal plants, bacterial and fungal fermentation broths, and natural product-based combinatorial libraries as sources of novel chemical structures, we will pursue the following specific aims: (1) to implement a multi-well-based screening assay for inhibitors of cdc25 phosphatase activity, and (2) to develop and place on-line a high-volume screen for inhibitors of the protein kinase activity of the cyclin D-cdk4 complex. Identified inhibitors of these cell-cycle targets will be subjected to mechanistic evaluations in experimental model systems in our laboratory, and will be tested for clinically-relevant anti-tumor activities by the core components of our drug discovery group. The objectives of this Core are to identify, from among compounds exhibiting activity in the biochemical target screens, those compounds that possess significant growth inhibitory activity against human tumor cells in vitro. This information will be used to determine which compounds require chemical modification to improve cell bioavailablity etc., and which compounds are taken for in vivo testing by Core C. We will routinely use a panel of 7 human tumor cell lines that include 2 breast, 2 colon, 2 prostate, an ovarian and a leukemia cell line. This will allow us to compare drug activity with a panel of generally intractable human solid tumor types and a generally responsive human tumor type (leukemia). The panel includes human solid tumors that will be studied as xenografts in vivo in Core C. We also have available panels of low passage human primary tumor cell lines, including breast and prostate, and cells engineered to overexpress the target of interest for specialized screening. Pharmacokinetic studies will be done on lead compounds to aid their preclinical development and to provide information for chemical modification to improve biological activity.