LOCAL SEQUENCE REQUIREMENTS FOR DNA CLEAVAGE BY MAMMALIAN TOPOISOMERASE-II IN THE PRESENCE OF DOXORUBICIN
LOCAL SEQUENCE REQUIREMENTS FOR DNA CLEAVAGE BY MAMMALIAN TOPOISOMERASE-II IN THE PRESENCE OF DOXORUBICIN
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DOI：
10.1093/nar/18.22.6611
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发表时间：
1990-11-25
影响因子：
14.9
通讯作者：
POMMIER, Y
中科院分区：
文献类型：
--
作者：
CAPRANICO, G;KOHN, KW;POMMIER, Y
阿霉素是一种DNA插入剂，是几种抗癌药物之一，已被发现可以稳定拓扑异构酶II在药物特异性DNA位点的切割复合物。测定了SV40基因组中阿霉素稳定位点的分布和DNA序列环境。这些位点主要集中在核基质相关区域，而在复制起点附近几乎不存在，包括21bp和72bp串联重复序列中的增强子序列。在DNA序列水平定位的97个阿霉素稳定位点中，没有一个与在没有药物的情况下在同一区域检测到的90个拓扑异构酶II切割位点一致。90个仅酶位点的切割被阿霉素抑制，即使在低浓度的药物下也不会被刺激。所有的阿霉素稳定位点在每对链断裂的至少一个成员的3”末端都有A，这将构成拓扑异构酶II双链断裂。相反，没有一个纯酶位点在相反链上的相应位置同时具有A。因此，阿霉素稳定裂解的3“-A要求与仅酶裂解不相容，并解释了两类位点的互斥性。
Doxorubicin, a DNA-intercalator, is one of several anti-cancer drugs that have been found to stabilizes topoisomerase II cleavage complexes at drug-specific DNA sites. The distribution and DNA sequence environments of doxorubicin-stabilized sites were determined in the SV40 genome. The sites were found to be most concentrated in the major nuclear matrix-associated region and nearly absent in the vicinity of the replication origin including the enhancer sequences in the 21-bp and 72-bp tandem repeats. Among 97 doxorubicin-stabilized sites that were localized at the DNA sequence level, none coincided with any of the 90 topoisomerase II cleavage sites detected in the same regions in the absence of drug. Cleavage at the 90 enzyme-only sites was inhibited by doxorubicin and never stimulated even at low drug concentrations. All of the doxorubicin-stabilized sites had an A at the 3'' terminus of at least one member of each pair of strand breaks that would constitute a topoisomerase II double-strand scission. Conversely, none of the enzyme-only sites had an A simultaneously at the corresponding positions on opposite strands. The 3''-A requirement for doxorubicin-stabilized cleavage is therefore incompatible with enzyme-only cleavage and explains the mutual exclusivity of the two classes of sites.