Inhibition of human DNA topoisomerase II by hydroquinone and p-benzoquinone, reactive metabolites of benzene
Inhibition of human DNA topoisomerase II by hydroquinone and p-benzoquinone, reactive metabolites of benzene
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DOI：
10.2307/3433173
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发表时间：
1996-12-01
影响因子：
10.4
通讯作者：
Kalf, GF
中科院分区：
文献类型：
--
作者：
Hutt, AM;Kalf, GF
人类长期接触苯（BZ）会导致急性髓细胞白血病（AML）。BZ和治疗相关的继发性AML的特征都是染色体易位，可能由不适当的重组事件发生。DNA拓扑异构酶II（topo II）是复制、重组、染色体分离和染色体结构所必需的巯基（SH）依赖性内切核酸酶。Topo II在嘌呤（R）/嘧啶（Y）重复序列处切割DNA，这些重复序列已被证明在体内具有高度重组性。某些抗白血病药物稳定RY重复序列处的topo II-DNA切割复合物，这导致在白血病中观察到的类型的易位。在髓系祖细胞中，氢醌（HQ）在过氧化物酶介导的反应中代谢为对苯醌（BQ）。BQ与SH依赖性酶的SH基团相互作用。因此，本研究的目的是确定HQ和BQ是否是拓扑异构酶II抑制剂。使用测定系统测试化合物抑制topo II活性的能力，所述测定系统取决于通过均质人topo II将连锁动质体DNA转化为开放和/或切口开放环状DNA，所述开放和/或切口开放环状DNA可以通过在1%琼脂糖-溴化乙锭凝胶中电泳而与连锁DNA分离。我们提供的初步数据表明，HQ和BQ引起的时间和浓度（μ M）依赖性抑制拓扑酶II活性。这些化合物可能与DNA形成加合物，但对电泳梯度中超螺旋和开放环状形式的迁移没有影响，并且BQ加合的KDNA可以被topo II解链。使用具有单个RY重复序列作为切割位点的pRYG质粒DNA，确定BQ不刺激线性DNA的产生，这表明通过稳定共价topo II-DNA切割复合物来抑制链断裂的topo II再连接。相反，BQ最有可能抑制SH依赖拓扑异构酶II结合到一个必不可少的SH组。BQ对拓扑异构酶II的抑制对可能参与BZ诱导的白血病发生起始的有害易位的形成具有影响。
Chronic exposure of humans to benzene (BZ) causes acute myeloid leukemia (AML). Both BZ and therapy-related secondary AML are characterized by chromosomal translocations that may occur by inappropriate recombinational events. DNA topoisomerase II (topo II) is an essential sulfhydryl (SH)-dependent endonuclease required for replication, recombination, chromosome segregation, and chromosome structure. Topo II cleaves DNA at purine(R)/pyrimidine(Y) repeat sequences that have been shown to be highly recombinogenic in vivo. Certain antineoplastic drugs stabilize topo II-DNA cleavage complexes at RY repeat sequences, which leads to translocations of the type observed in leukemia. Hydroquinone (HQ) is metabolized to p-benzoquinone (BQ) in a peroxidase-mediated reaction in myeloid progenitor cells. BQ interacts with SH groups of SH-dependent enzymes. Consequently, the aims of this research were to determine whether HQ and BQ are topo II inhibitors. The ability of the compounds to inhibit the activity of topo II was tested using an assay system that depends on the conversion, by homogeneous human topo II, of catenated kinetoplast DNA into open and/or nicked open circular DNA that can be separated from the catenated DNA by electrophoresis in a 1% agarose-ethidium bromide gel. We provide preliminary data that indicate that both HQ and BQ cause a time and concentration (mu M)-dependent inhibition of topo II activity. These compounds, which potentially can form adducts with DNA, have no effect on the migration of the supercoiled and open circular forms in the electrophoretic gradient, and BQ-adducted KDNA can be decatenated by topo II. Using a pRYG plasmid DNA with a single RY repeat as a cleavage site, it was determined that BQ does not stimulate the production of linear DNA indicative of an inhibition of topo II religation of strand breaks by stabilization of the covalent topo II-DNA cleavage complex. Rather, BQ most probably inhibits the SH-dependent topo II by binding to an essential SH group. The inhibition of topo II by BQ has implications for the formation of deleterious translocations that may be involved in BZ-induced initiation of leukemogenesis.