Woynarowski J M, McCarthy K, Reynolds B, Beerman T A, Denny W A
Roswell Park Cancer Institute, Buffalo, NY 14263.
Anticancer Drug Des. 1994 Feb;9(1):9-24.
Acridine-4-carboxamide and 2-(4-pyridyl)quinoline-8-carboxamide represent a new generation of antitumor intercalators related to amsacrine (m-AMSA), a classic topoisomerase II-targeted drug. We examined the ability of these tricyclic carboxamides to induce DNA lesions that reflect the stabilization of topoisomerase II cleavage complexes. DNA-protein cross-links (DPC) and DNA double-strand breaks (DSB) were assessed in mouse fibrosarcoma cells (line 935.1). DPC were rapidly formed and readily reversible. A bell-shape concentration dependence suggested a self-inhibition of DPC at higher drug levels. In isolated nuclei, DPC formation by 2-(4-pyridyl)quinoline-8-carboxamide required ATP and was inhibited by novobiocin, a topoisomerase II inhibitor. Acridine-4-carboxamide and 2-(4-pyridyl)quinoline-8-carboxamide were also potent inducers of DSB. In contrast to DPC, however, DNA breaks continued to increase with drug concentration. These DSB were masked (presumably by non-covalently associated proteins) when analyzed by nucleoid sedimentation. Thus, while both DPC and DSB seemed to be topoisomerase mediated, at least some DSB appeared to lack the enzyme bound covalently. DNA lesions by tricyclic carboxamides occurred, in general, at drug concentrations comparable to those needed to inhibit cell survival. Also, the tricyclic carboxamides inhibited the catalytic activity of isolated topoisomerase II. The results indicate that tricyclic carboxamides interfere with the action of topoisomerase II. However, the mechanisms of enzyme inhibition by these drugs differ from the classical trapping of topoisomerase in covalent cleavage complex m-AMSA.
吖啶-4-甲酰胺和2-(4-吡啶基)喹啉-8-甲酰胺代表了与安吖啶（m-AMSA，一种经典的靶向拓扑异构酶II的药物）相关的新一代抗肿瘤嵌入剂。我们研究了这些三环甲酰胺诱导DNA损伤的能力，这些损伤反映了拓扑异构酶II切割复合物的稳定。在小鼠纤维肉瘤细胞（935.1系）中评估了DNA-蛋白质交联（DPC）和DNA双链断裂（DSB）。DPC迅速形成且易于逆转。钟形浓度依赖性表明在较高药物水平下DPC存在自我抑制。在分离的细胞核中，2-(4-吡啶基)喹啉-8-甲酰胺形成DPC需要ATP，并且被拓扑异构酶II抑制剂新生霉素抑制。吖啶-4-甲酰胺和2-(4-吡啶基)喹啉-8-甲酰胺也是DSB的有效诱导剂。然而，与DPC不同，DNA断裂随着药物浓度的增加而持续增加。当通过核仁沉降分析时，这些DSB被掩盖（可能是由非共价结合的蛋白质）。因此，虽然DPC和DSB似乎都是由拓扑异构酶介导的，但至少一些DSB似乎缺乏共价结合的酶。三环甲酰胺引起的DNA损伤通常发生在与抑制细胞存活所需浓度相当的药物浓度下。此外，三环甲酰胺抑制分离的拓扑异构酶II的催化活性。结果表明三环甲酰胺干扰拓扑异构酶II的作用。然而，这些药物抑制酶的机制不同于经典的将拓扑异构酶捕获在共价切割复合物m-AMSA中的机制。
