Ding Z M, Hurley L H
Drug Dynamics Institute, College of Pharmacy, University of Texas, Austin 78712.
Anticancer Drug Des. 1991 Nov;6(5):427-52.
U-77779 is a symmetrical dimer of the spirocyclopropyl alkylating subunit of (+)-CC-1065 in which the linker consists of two indole subunits separated by a ureido group. This compound was synthesized by scientists of the Upjohn Company and was found to be more active in both anti-tumor efficacy and cytotoxicity than its mono-alkylating analogs. Using three different 21-base pair DNA duplexes containing U-77779 reactive sequences, we have shown that U-77779 produces a stable interstrand cross-linked species that loses its internal self complementarity. A comparison of U-77779 with the mono-alkylating analogs of (+)-CC-1065 shows that it appears to have an increased sequence selectivity such that, while mono-alkylating compounds like (+)-CC-1065 react at more than one site, U-77779 reacts only at sites where there are two suitably positioned alkylation sites. Chemical footprinting with 1,10-phenanthroline-copper complex revealed a six base pair cross-linked region between the two covalently modified adenines with modulated cleavage outside this region. In the case of hydroxyl radical footprinting, considerable variability of the extent of cleavage within the cross-linked sequence was found. These results are discussed in terms of likely induced conformational changes in DNA. In contrast to (+)-CC-1065, non-denaturing gel electrophoresis did not reveal any net bending of DNA due to U-77779, which we believe is due to the 180 degrees out-of-phase bending produced on opposite strands of DNA by the cross-linker.
U-77779是(+)-CC-1065的螺环丙基烷基化亚基的对称二聚体，其中连接体由两个被脲基隔开的吲哚亚基组成。该化合物由Upjohn公司的科学家合成，发现其在抗肿瘤功效和细胞毒性方面均比其单烷基化类似物更具活性。使用三种包含U-77779反应序列的不同21碱基对DNA双链体，我们已表明U-77779产生一种稳定的链间交联物种，该物种失去其内部自我互补性。将U-77779与(+)-CC-1065的单烷基化类似物进行比较表明，它似乎具有更高的序列选择性，即虽然像(+)-CC-1065这样的单烷基化化合物在多个位点发生反应，但U-77779仅在有两个适当定位的烷基化位点的位点发生反应。用1,10-菲咯啉-铜配合物进行化学足迹分析揭示了两个共价修饰的腺嘌呤之间的一个六碱基对交联区域，该区域外的切割受到调节。在羟基自由基足迹分析的情况下，发现交联序列内切割程度存在相当大的变异性。这些结果根据DNA中可能诱导的构象变化进行了讨论。与(+)-CC-1065不同，非变性凝胶电泳未显示由于U-77779导致的DNA有任何净弯曲，我们认为这是由于交联剂在DNA的相反链上产生的180度异相弯曲所致。
