Lambert B, Segal-Bendirdjian E, Esnault C, Le Pecq J B, Roques B P, Jones B, Yeung A T
Unité de Physicochimie Macromoléculaire, URA 158 CNRS, U140 INSERM, Institut Gustave Roussy, Villejuif, France.
Anticancer Drug Des. 1990 Feb;5(1):43-53.
Ditercalinium (NSC 335153) was synthesized as a bifunctional DNA intercalator. It is made of two 7-H pyridocarbazole rings joined by a rigid bis-ethyl bispiperidine chain. It binds to DNA with high affinity and elicits anti-tumor activity on a variety of animal tumors. 1H n.m.r. studies of ditercalinium bis-intercalated into d(CpGpCpG)2 have shown that the intercalation process occurs from the large groove of the DNA helix while the two intercalated rings are separated by two base pairs. Because of the linking chain rigidity of ditercalinium, DNA conformation has to be altered to permit the intercalation of the two rings. DNA must be bent toward the minor groove. In E. coli, ditercalinium elicits a specific toxicity on polA strains which is suppressed by an additional uvrA mutation. In vitro, the purified UvrA and UvrB proteins bind to the DNA-ditercalinium complex in an ATP dependent manner. The UvrABC complex induces single-strand nicks, but only when ditercalinium is bound to negatively supercoiled DNA. The life-time of the UvrAB-DNA-ditercalinium complex is greater than 50 min when free ditercalinium concentration is maintained constant in the incubation medium. The cytotoxicity of ditercalinium in E. coli results from the induction of a futile and abortive DNA repair. The reversible ditercalinium-DNA complex mimics a bulky DNA lesion, yet the UvrABC endonuclease is unable to cope with a reversible lesion since it cannot eliminate the causative agent. The interaction of UvrA and UvrB proteins has also been studied with DNA and other DNA-binding drugs forming high-affinity complexes such as distamycin. The Uvr protein recognition process appears to be associated with specific DNA structural alterations. In eukaryotic cells, ditercalinium is concentrated in mitochondria. Mitochondrial DNA is rapidly and totally degraded. Mitochondrial DNA coded proteins being no longer synthesized, the respiratory chain is progressively inactivated. The stimulation of the glycolytic pathway allows the cells to continue growth for several generations. Dihydro-orotate dehydrogenase is located in the inner membrane of mitochondria and its activity is dependent on mitochondria energization. It becomes inactive after ditercalinium treatment. A drop of the pyrimidine pool is then observed. Complementation of treated cells with uridine decreases 10-fold the ditercalinium toxicity. The cellular delayed toxicity of ditercalinium results from the slow induction of a pyrimidineless state associated with the progressive inactivation of mitochondria. The results show that DNA structural alterations induced by reversible drug-DNA complexes can be recognized by DNA repair enzymes.(ABSTRACT TRUNCATED AT 400 WORDS)
地特卡林（NSC 335153）被合成为一种双功能DNA嵌入剂。它由两个7-H吡啶并咔唑环通过刚性双乙基双哌啶链连接而成。它与DNA具有高亲和力，并对多种动物肿瘤具有抗肿瘤活性。对嵌入d（CpGpCpG）2的地特卡林进行的1H核磁共振研究表明，嵌入过程从DNA螺旋的大沟发生，而两个嵌入环被两个碱基对隔开。由于地特卡林连接链的刚性，DNA构象必须改变以允许两个环嵌入。DNA必须向小沟弯曲。在大肠杆菌中，地特卡林对polA菌株具有特异性毒性，这种毒性可被额外的uvrA突变抑制。在体外，纯化的UvrA和UvrB蛋白以ATP依赖的方式与DNA-地特卡林复合物结合。UvrABC复合物诱导单链切口，但仅当地特卡林与负超螺旋DNA结合时。当孵育培养基中游离地特卡林浓度保持恒定时，UvrAB-DNA-地特卡林复合物的寿命大于50分钟。地特卡林在大肠杆菌中的细胞毒性源于无效和流产性DNA修复的诱导。可逆的地特卡林-DNA复合物模拟了一种大的DNA损伤，但UvrABC核酸内切酶无法应对可逆损伤，因为它无法消除致病因子。还研究了UvrA和UvrB蛋白与DNA以及其他形成高亲和力复合物（如偏端霉素）的DNA结合药物的相互作用。Uvr蛋白识别过程似乎与特定的DNA结构改变有关。在真核细胞中，地特卡林集中在线粒体中。线粒体DNA迅速且完全降解。线粒体DNA编码的蛋白质不再合成，呼吸链逐渐失活。糖酵解途径的刺激使细胞能够继续生长几代。二氢乳清酸脱氢酶位于线粒体内膜，其活性依赖于线粒体的能量供应。地特卡林处理后它会失活。然后观察到嘧啶池下降。用尿苷补充处理过的细胞可使地特卡林毒性降低10倍。地特卡林的细胞延迟毒性源于与线粒体逐渐失活相关的无嘧啶状态的缓慢诱导。结果表明，可逆药物-DNA复合物诱导的DNA结构改变可被DNA修复酶识别。（摘要截短至400字）
