INHIBITION OF DNA TOPOISOMERASES I AND II BY DMP840

DMP-840是一种新型的抗肿瘤药物--双-萘亚胺类药物。 I期临床试验。在临床前研究中，DMP 840产生了 5/6横纹肌肉瘤在无毒浓度下的完全回归 在免疫剥夺的小鼠身上作为异种移植生长。我们的长期目标是 DMP 840治疗儿童慢性阻塞性肺疾病的疗效观察 实体瘤。 初步生化数据表明，DMP 840是一种新化合物 它通过不同的机制抑制DNA拓扑异构酶I和II 来自目前临床上使用的拓扑异构酶抑制剂。因为 DMP-840抑制拓扑异构酶的分子机制 水平可能是决定肿瘤类型的一个因素 哪种DMP 840是有效的，以及它可以与哪些药物结合 有效地，我们建议确定抑制的机制 DMP 840的拓扑异构酶I和II。根据初步数据，我们的 假设DMP 840阻止了拓扑异构酶I和II的结合 转移到DNA上。如果这一假设是正确的，DMP 840的细胞毒性可能是 细胞周期非依赖性，是治疗实体瘤的重要因素 它们的生长分数往往很低。我们将使用细胞系 从对DMP 840具有不同敏感性的实体肿瘤建立 检测该化合物对拓扑异构酶功能的影响。 完好无损的细胞。我们还将尝试将药物效力与 拓扑异构酶I/II水平，以单细胞为基础 荧光数字成像显微镜。然后分离出的酶将被 用于确定拓扑异构酶催化循环中的哪一步 DMP 840的抑制作用及DMP 840对其物理相互作用的影响 含有DNA、酶或DNA/酶复合体的化合物。这些数据将 然后用于DNA/药物/酶的分子模拟预测 互动。 此外，在动物模型中，DMP 840似乎相对无毒。 然而，拓扑异构酶抑制剂是已知的诱变剂。因此， 将评估DMP 840的诱变潜力。我们的工作 假设是因为DMP 840有不止一个细胞靶点， 这些目标中的每一个都需要同时突变才能 允许细胞存活；因此，DMP 840的诱变性可能比 目前批准用于临床的拓扑异构酶抑制剂。贯穿始终 在这些实验中，我们将比较DMP和抑制 拓扑异构酶I或II确定其相对疗效和毒性 这三类化合物。

DMP 840 is one of a new class of antitumor agents, bis-naphthalimides, in Phase I clinical trials. In preclinical studies DMP 840 has produced complete regressions at nontoxic concentrations in 5/6 rhabdomyosarcomas grown as xenografts in immune-deprived mice. Our long range goal is to determine the efficacy of DMP 840 in treating pediatric patients with solid tumors. Preliminary biochemical data indicate that DMP 840 is a novel compound in that it inhibits DNA topoisomerases I and II by a mechanisms different from inhibitors of topoisomerases now used clinically. Because the mechanisms of inhibition of topoisomerases by DMP 840 at the molecular level is likely to be a factor in determining the tumor types against which DMP 840 is active and the drugs with which it can be combined effectively, we propose to determine the mechanism of inhibition of topoisomerases I and II by DMP 840. Based on preliminary data, our hypothesis is that DMP 840 prevents the binding of topoisomerases I and II to DNA. If this hypothesis is correct, the cytotoxicity of DMP 840 may be cell cycle-independent, and important factor in treating solid tumors which frequently have low growth fractions. We will use cell lines established from solid tumors having different sensitivities to DMP 840 to examine the effect of this compound on the function of topoisomerases in intact cells. We will also attempt to correlate drug potency with topoisomerase I/II levels, with quantitation on a single cell basis by fluorescence digital imaging microscopy. Isolated enzymes will then be used to determine which step in the catalytic cycle of topoisomerases is inhibited by DMP 840 and effect of DMP 840 on the physical interaction of the compound with DNA, enzyme, or DNA/enzyme complex. These data will then be used for molecular modeling predictions of DNA/drug/enzyme interaction. Additionally, DMP 840 appears to be relatively nontoxic in animal models. However, topoisomerase inhibitors are known to be mutagenic. Therefore, the mutagenic potential of DMP 840 will be evaluated. Our working hypothesis is that because DMP 840 has more than one cellular target, simultaneous mutations would be required in each of these targets to permit cell survival; therefore, DMP 840 may be less mutagenic than topoisomerase inhibitors currently approved for clinical use. Throughout these experiments, we will compare DMP with agents that inhibit either topoisomerase I or II to establish the relative efficacy and toxicity of the three classes of compounds.