MODULATION OF NUCLEOSIDE TRANSPORT IN CHEMOTHERAPY

描述(摘自申请者摘要)：核苷的摄取 通过哺乳动物细胞是复杂的，并由多种转运蛋白介导 它们的底物专一性和对抑制剂的敏感性不同。 核苷转运体有两大类。第一，平衡性 (E)也称为促进扩散机制；第二，集中 (C)。均衡式又分为两个部分。这是基于 对NBMPR敏感，ES敏感，EI不敏感。全 浓缩型转运体对NBMPR(1微摩尔)不敏感(Ci) 并根据承印物的特性分为3种，因此CIF接受 甲霉素B，Cit，胸腺嘧啶核苷和CIb，能接受广泛的核苷。 这个项目的基本假设是选择性化疗 核苷转运抑制剂与抗代谢药联合使用 可以基于肿瘤的核苷转运特性而开发 以及限制剂量的正常组织。在以前的资助期间进行的研究 周期确定了肿瘤细胞系的核苷转运特性，并 骨髓和肠道的临界正常细胞，并已确定 通过联合使用核苷抑制剂可以利用的差异 用胸腺嘧啶脱氢酶合成的抑制物转运。申请人的 该小组和其他人也发现了核苷转运的变化 髓系白血病细胞在分化过程中可能被利用 提高嘌呤核苷类似物抗白血病的活性。 因此，这个项目的继续将检验扩展的假说 在核苷转运方面存在着内在的差异 正常组织和一些肿瘤(目标3)，以及可以诱导的差异 在一些肿瘤中，通过分化试剂，这可以被利用 治疗目的。这一假说将通过体外和 黄曲霉毒素对胸苷酸合酶抑制剂调节作用的体内研究 核苷转运抑制剂治疗横纹肌肉瘤(目标1和2)； 嘌呤核苷类似物(具体地说， 2-氯脱氧腺苷(2-CDA)对髓系细胞的毒性 白血病细胞(目标4)。一些核苷的最新克隆 转运体将允许将这些研究进行到分子水平， 以及分子试剂和分析方法的发展(目标5)需要 测定正常组织和肿瘤的核苷转运体表型 从小样本中提取。预计体外和动物研究， 分子试剂的发展将为今后的研究提供良好的基础。 将这些治疗方法从实验室转化为 诊所。

DESCRIPTION (Adapted from Applicant's Abstract): The uptake of nucleosides by mammalian cells is complex and mediated by multiple transport proteins that differ in their substrate specificity and sensitivity to inhibitors. There are two major groups of nucleoside transporters. First, equilibrative (e) also known as facilitated diffusion mechanism and second, concentrative (c). Equilibrative is further divided into two. This is based on the sensitivity to NBMPR, so es is sensitive and ei is insensitive. All concentrative type transporters are insensitive (ci) to NBMPR (1 micromolar) and depending on substrate specificity are divided into 3, hence cif accepts formycin B, cit, thymidine, and cib, accepts broad range of nucleosides. The basic hypothesis of this project has been that selective chemotherapy using nucleoside transport inhibitors in combination with antimetabolites can be developed based on the nucleoside transport properties of the tumor and the dose-limiting normal tissues. Studies during the previous funding period have defined nucleoside transport properties of tumor cell lines and critical normal cells of the bone marrow and intestine, and have identified differences that might be exploited by combining inhibitors of nucleoside transport with inhibitors of de novo thymidylate synthesis. The applicant's group and others have also identified changes in nucleoside transport in myeloid leukemia cells during differentiation that might be exploited to increase the activity of purine nucleoside analogs against this leukemia. Thus, the continuation of this project will test the expanded hypothesis that there are both intrinsic differences in nucleoside transport between normal tissues and some tumors (Aim 3), and differences that can be induced in some tumors by differentiating agents, that can be exploited for therapeutic purposes. This hypothesis will be tested through in vitro and in vivo studies of the modulation of thymidylate synthase inhibitors by nucleoside transport inhibitors in rhabdomyosarcoma (Aims 1 and 2); and in vitro studies of the modulation of purine nucleoside analog (specifically, 2-chlorodeoxyadenosine, 2-CdA) toxicity by differentiating agents in myeloid leukemia cells (Aim 4). The recent cloning of some of the nucleoside transporters will permit these studies to be carried to the molecular level, and the development of molecular reagents and assays (Aim 5) needed to determine the nucleoside transporter phenotype of normal tissues and tumors from small samples. It is anticipated that the in vitro and animal studies, and the development of the molecular reagents will provide a sound basis for the translation of these therapeutic approaches from the laboratory to the clinic.