Etiévant C, Kruczynski A, Barret J M, Perrin D, van Hille B, Guminski Y, Hill B T
Division de Cancérologie Expérimentale I, Centre de Recherche Pierre Fabre, Castres, France.
Cancer Chemother Pharmacol. 2000;46(2):101-13. doi: 10.1007/s002800000133.
F 11782 (2",3"-bis pentafluorophenoxyacetyl-4",6"-ethylidene-beta-D-glucoside of 4'-phosphate-4'-dimethylepipodophyllotoxin, di-N-methyl glucamine salt) is a newly synthesized dual catalytic inhibitor of topoisomerases I and II with major in vivo antitumour activity. In this study, we compared and contrasted F 11782 with three other known inhibitors of both these nuclear enzymes, namely aclarubicin. intoplicin and TAS-103, and established its novel mechanism of action.
In vitro growth-inhibitory effects against a panel of murine and tumour cell lines were measured by cell counting, clonogenicity or tetrazolium metabolic dye (MTT) assays. In vivo antitumour activities were evaluated against two murine tumour models (i.v. P388 leukaemia and s.c. B16 melanoma). Finally, interactions with either DNA or DNA-topoisomerases were determined using various methodologies: DNA-intercalator displacement, pBR322 DNA relaxation, kDNA decatenation, topoisomerase II extractability measurements, stabilization of topoisomerase-induced cleavable complexes (CC) in vitro and in cells, and gel retardation assays.
F 11782 had a different profile of sensitivities and proved generally less cytotoxic than the other dual inhibitors tested in vitro, while showing significantly superior antitumour activity in vivo. F 11782, which did not stabilize CC either in vitro or in cells, was the only compound of this series capable of inhibiting the catalytic activity of both DNA-topoisomerases without interacting with DNA, and of completely impairing the binding of these nuclear proteins to DNA. Moreover, only cotreatment of cells in vitro with F 11782 enhanced the cytotoxic activity of etoposide.
These results emphasize the novel mechanism of action of F 11782 vis-a-vis the other dual inhibitors of topoisomerases I and II and so augur well for its future clinical development.
F 11782（4'-磷酸-4'-二甲基表鬼臼毒素的2",3"-双五氟苯氧基乙酰基-4",6"-亚乙基-β-D-葡萄糖苷，二-N-甲基葡糖胺盐）是一种新合成的拓扑异构酶I和II的双重催化抑制剂，具有主要的体内抗肿瘤活性。在本研究中，我们将F 11782与其他三种已知的这两种核酶抑制剂（即阿柔比星、英托利辛和TAS-103）进行了比较和对比，并确定了其新的作用机制。
通过细胞计数、克隆形成或四唑代谢染料（MTT）测定法测量对一组小鼠和肿瘤细胞系的体外生长抑制作用。针对两种小鼠肿瘤模型（静脉注射P388白血病和皮下接种B16黑色素瘤）评估体内抗肿瘤活性。最后，使用各种方法确定与DNA或DNA-拓扑异构酶的相互作用：DNA嵌入剂置换、pBR322 DNA松弛、kDNA解连环、拓扑异构酶II可提取性测量、体外和细胞内拓扑异构酶诱导的可裂解复合物（CC）的稳定以及凝胶阻滞测定。
F 11782具有不同的敏感性特征，并且在体外测试中通常比其他双重抑制剂的细胞毒性小，而在体内显示出显著优越的抗肿瘤活性。F 11782在体外或细胞内均不稳定CC，是该系列中唯一能够抑制两种DNA-拓扑异构酶的催化活性而不与DNA相互作用，并且完全损害这些核蛋白与DNA结合的化合物。此外，仅在体外将细胞与F 11782共同处理可增强依托泊苷的细胞毒性活性。
这些结果强调了F 11782相对于拓扑异构酶I和II的其他双重抑制剂的新作用机制，因此对其未来的临床开发预示良好。
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