Yamada M, O'Regan E, Brown R, Karran P
Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Hertfordshire EN6 3LD, UK.
Nucleic Acids Res. 1997 Feb 1;25(3):491-6. doi: 10.1093/nar/25.3.491.
The antitumor agent cis-diamminedichloroplatinum(II) (cisplatin) introduces cytotoxic DNA damage predominantly in the form of intrastrand crosslinks between adjacent purines. Binding assays using a series of duplex oligonucleotides containing a single 1,2 diguanyl intrastrand crosslink indicate that human cell extracts contain factors that preferentially recognise this type of damage when the complementary strand contains T opposite the 3', and C opposite the 5'guanine in the crosslink. Under the conditions of the band-shift assay used, little binding is observed if the positions of the T and C are reversed in the complementary strand. Similarly, duplexes containing CC or TT opposite the crosslink are recognised relatively poorly. The binding activity is absent from extracts of the colorectal carcinoma cell lines LoVo and DLD-1 in which the hMutSalpha mismatch recognition complex is inactivated by mutation. Extensively purified human hMutSalpha exhibits the same substrate preference and binds to the mismatched platinated DNA at least as well as to an identical unplatinated duplex containing a single G.T mismatch. It is likely, therefore, that human mismatch repair may be triggered by 1,2 diguanyl intrastrand crosslinks that have undergone replicative bypass.
抗肿瘤药物顺 - 二氯二氨合铂（II）（顺铂）主要以相邻嘌呤之间的链内交联形式引入细胞毒性DNA损伤。使用一系列含有单个1,2 - 二鸟嘌呤链内交联的双链寡核苷酸进行的结合试验表明，当互补链在交联处3'端相对位置含有T，5'端鸟嘌呤相对位置含有C时，人细胞提取物中含有优先识别这种类型损伤的因子。在所使用的凝胶迁移试验条件下，如果互补链中T和C的位置颠倒，则观察到的结合很少。同样，在交联相对位置含有CC或TT的双链体被识别的程度相对较差。在结直肠癌细胞系LoVo和DLD - 1的提取物中不存在结合活性，在这些细胞系中hMutSα错配识别复合物因突变而失活。经过广泛纯化的人hMutSα表现出相同的底物偏好，并且与错配的铂化DNA结合的能力至少与与含有单个G.T错配的相同未铂化双链体一样好。因此，人错配修复很可能由经历复制性绕过的1,2 - 二鸟嘌呤链内交联触发。
