STRUCTURE/FUNCTION AND REGULATION OF MRP

细胞对细胞毒药物的耐药性是阻碍 成功治疗播散性恶性肿瘤。新技术的出现 反复化疗后耐药细胞因以下原因而加重 多药耐药(MDR)，即存活的细胞暴露于一种天然的 产品药物同时对其他天然药物产生抗药性 产品药品。我们现在已经证明了MRP，一个最近描述的 ABC运输机超家族的成员，能够赋予 多药耐药。这一活动此前被认为是 仅与MDR1关联。虽然MRP的拓扑结构类似于 MDR1，由两个亲水性的ATP结合域组成，连接到 氨基末端疏水域，我们的实验表明MRP 赋予了一种独特的多药耐药性模式。与MDRI一样，MRP授予 对各种亲脂剂的抗药性，包括阿霉素， 柔红霉素、VP-16、长春新碱、放线菌素D和米托蒽醌。在……里面 然而，相比之下，它对天然产品几乎没有活性。 紫杉醇和长春花碱。我们的研究进一步表明，MRP是 位于细胞膜上，其独特的作用机制 涉及促进药物在细胞质细胞器中的积累，从而 保护重要的核和细胞目标，并导致减少 细胞药物水平。我们检测了15例正常人的MRP表达 人体组织，以及包括乳腺在内的55种肿瘤细胞系中的54种， 结肠癌、肺癌、肉瘤、胃癌、黑色素瘤和星形细胞瘤。把这些放在一起 数据表明，MRP可能在固有的、 许多常见的获得性、细胞毒性耐药机制 实体瘤。鉴于其对大体积亲脂化合物的活性，它 也可能在保护人体免受致癌外源物质的伤害方面发挥作用。这 提案包含细胞和分子生物学实验，以 阐明MRP的作用机制及其结构功能关系 以及影响其表达的因素和机制。这 信息将有助于我们对分子框架的理解 的抗药性，这是改进设计所必需的基本原理 癌症治疗。

Cellular resistance to cytotoxic drugs is a major obstacle to the successful treatment of disseminated malignancies. The emergence of resistant cells after repeated courses of chemotherapy is exacerbated by multidrug resistance (MDR), in which surviving cells exposed to one natural product drug become simultaneously resistant to a spectrum of other natural product drugs. We have now demonstrated that mrp, a recently described member of the ABC superfamily of transporters, is capable of conferring multidrug resistance. This activity was previously thought to be associated only with MDR1. Although the topology of mrp is similar to that of mDR1, consisting of two hydrophilic ATP binding domains appended to amino terminal hydrophobic domaines, our experiments indicate that mrp confers a distinct pattern of multidrug resistance. Like MDRI, mrp confers resistance to a variety of lipophilic agents, including, doxorubicin, daunorubicin, VP-16, vincristine, actinomycin D, and mitoxantrone. In contrast however, it has little or no activity for the natural products taxol and vinblastine. Our studies have further shown that the mrp is located in cytoplasmic membranes, and that its distinct mechanism of action involves facilitating drug accumulation in cytoplasmic organelles, thereby protecting vital nuclear and cellular targets, and leading to reduced cellular drug levels. We have detected mrp expression in each of 15 normal human tissues, as well as in 54 of 55 tumor cell lines, including breast, colon, lung, sarcoma, gastric, melanoma and astrocytoma. Together these data suggest that mrp may play an important role in the inherent, and possibly acquired, cytotoxic drug resistance mechanisms of many common solid tumors. In view of its activity for bulky lipophilic compounds it may also play a role in protection from carcinogenic xenobiotics. This proposal contains cellular and molecular biological experiments to elucidate the mrp mechanism of action, its structure function relationships and the agents and mechanism that influence its expression. This information will contribute to our understanding of the molecular framework of drug resistance, which is necessary for the rationale design of improved cancer treatments.