Ciccarelli R B, Solomon M J, Varshavsky A, Lippard S J
Biochemistry. 1985 Dec 17;24(26):7533-40. doi: 10.1021/bi00347a005.
The mechanism of action of the antitumor drug cis-diamminedichloroplatinum(II), cis-DDP, was investigated by using the approximately 5200 base pair (bp) chromosome of simian virus 40 (SV40) as an in vivo chromatin model. Comparative studies were also carried out with the clinically ineffective isomer trans-DDP. Although 14 times more trans- than cis-DDP in the culture medium is required to inhibit SV40 DNA replication in SV40-infected green monkey CV-1 cells, the two isomers are equally effective at inhibiting replication when equimolar amounts are bound to SV40 DNA in vivo. Since both isomers are transported into CV-1 cells at similar rates, differential uptake cannot account for the greater ability of cis-DDP to inhibit SV40 DNA replication. Rather, this result is explained by the finding that cis-DDP-DNA adducts accumulate continuously over the incubation period, whereas trans-DDP binding to DNA reaches a maximum at 6 h and thereafter decreases dramatically. We suggest that the different accumulation behavior of cis-DDP and trans-DDP on DNA is due to their differential repair in CV-1 cells. A variety of non-histone proteins, including SV40 capsid proteins but virtually no histones, are cross-linked to SV40 DNA in vivo by either cis- or trans-DDP. More DNA-protein cross-links are formed by trans-DDP than by cis-DDP at equivalent amounts of DNA-bound platinum.(ABSTRACT TRUNCATED AT 250 WORDS)
利用猿猴病毒40（SV40）约5200碱基对（bp）的染色体作为体内染色质模型，研究了抗肿瘤药物顺二氯二氨铂（II）（顺铂，cis-DDP）的作用机制。还对临床无效的异构体反铂（trans-DDP）进行了比较研究。虽然在感染SV40的绿猴CV-1细胞中，培养基中反铂抑制SV40 DNA复制所需的量是顺铂的14倍，但当等摩尔量的两种异构体在体内与SV40 DNA结合时，它们抑制复制的效果相同。由于两种异构体以相似的速率转运到CV-1细胞中，因此摄取差异不能解释顺铂抑制SV40 DNA复制的能力更强的原因。相反，这一结果可以通过以下发现来解释：顺铂-DNA加合物在孵育期间持续积累，而反铂与DNA的结合在6小时达到最大值，此后急剧下降。我们认为，顺铂和反铂在DNA上不同的积累行为是由于它们在CV-1细胞中的修复差异所致。多种非组蛋白，包括SV40衣壳蛋白，但几乎没有组蛋白，在体内通过顺铂或反铂与SV40 DNA交联。在等量的与DNA结合的铂的情况下，反铂形成的DNA-蛋白质交联比顺铂更多。（摘要截短于250字）
