INHIBITION OF DNA TOPOISOMERASES I AND II BY DMP840

双萘酰亚胺是一种新型抗肿瘤药物， I期临床试验。 在临床前研究中， 5/6例横纹肌肉瘤在无毒浓度下完全消退 作为异种移植物在免疫剥夺小鼠中生长。 我们的长期目标是 确定THE840治疗儿童患者的疗效， 实体瘤 初步的生物化学数据表明，P1840是一种新的化合物， 它通过不同的机制抑制DNA拓扑异构酶I和II 现在临床上使用的拓扑异构酶抑制剂。 因为 在分子水平上探讨了RP840抑制拓扑异构酶的机制 水平可能是确定肿瘤类型的一个因素， 哪种药物是有效的，以及它可以与哪些药物联合使用。 有效地，我们建议确定抑制的机制， 拓扑异构酶I和II的表达。 根据初步数据，我们 一种假设是，RP840阻止了拓扑异构酶I和II的结合 到DNA 如果这一假设是正确的，那么， 不依赖细胞周期，是治疗实体瘤的重要因素 其通常具有低生长分数。 我们将使用细胞系 从对HPLC840具有不同敏感性的实体瘤建立， 检查这种化合物对拓扑异构酶功能的影响， 完整的细胞 我们还将尝试将药物效力与 拓扑异构酶I/II水平，在单细胞基础上通过 荧光数字成像显微术。 分离的酶将被 用于确定拓扑异构酶催化循环中的哪一步是 抑制和影响的物理相互作用， 与DNA、酶或DNA/酶复合物的化合物。 这些数据将 然后用于DNA/药物/酶的分子建模预测 互动 此外，在动物模型中，E840似乎相对无毒。 然而，已知拓扑异构酶抑制剂具有致突变性。 因此，我们建议， 将评价P1840的致突变潜力。 我们的工作 假设是因为EMP840具有多于一个细胞靶， 在这些目标中的每一个中需要同时突变， 允许细胞存活;因此，BS840的致突变性可能低于 拓扑异构酶抑制剂目前已被批准用于临床。 在整个 在这些实验中，我们将比较抗肿瘤药物和抑制 拓扑异构酶I或II，以确定 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.