ADDUCTS OF MITOMYCIN C WITH NUCLEOTIDES

丝裂霉素C（Mitomycin C，MC）是一种广泛应用的抗生素和抗肿瘤药物 在临床癌症化疗中。 它的作用方式是 20多年来， 自从发现它诱导DNA的共价交联以来。 最近，我们阐明了MC激活的基本化学 及其与DNA的最终反应产物，包括MC-DNA 交联 我们的目标是将三大要素 反应产物对MC的生物效应，即 确定（a）哪一种对抗肿瘤和细胞毒性更有效 （B）-为什么它更有效;（c）如何加强 在细胞中形成这种有效的反应。 的广泛和 长期目标是了解 丝裂霉素的抗肿瘤活性，并使这一知识 适用于癌症的新药设计和治疗方案 化疗 首先，将检查MC和DNA的三种加合物的 使用足迹技术定位特定的DNA序列 以及Ba 131消化作为工具。 每种加合物对 将通过检查构象来评估DNA构象 在一个位点上被三种修饰的寡核苷酸 加合物，作为模型。 细胞培养物中形成的加合物的测定将 用作（i）细胞内O2对交联的影响的探针 MC的效率，（ii）三种加合物的相对细胞毒性， (iii)通过细胞修复去除加合物的动力学。 切除 将在体外系统中研究加合DNA的修复，使用 单位点加合DNA片段。 两种MC类似物，更有效 将检查母体MC的分子基础， 通过比较它们的活性和DNA， 与MC的反应。

Mitomycin C (MC) is an antibiotic and antitumor agent widely used in clinical cancer chemotherapy. Its mode of action has been the subject of intensive study and speculation for more than 20 years, since the discovery that it induced covalent crosslinking of DNA. Recently we elucidated the basic chemistry of the activation of MC and its ultimate reaction products with DNA including the MC-DNA crosslink. Our objective is to relate each of the three major reaction products to the biological effects of MC, i.e. to determine (a) which is more effective for antitumor and cytotoxic activities, (b)-why is it more effective and (c) how to enhance the formation of such effective reactions in the cell. The broad and long-term objective is to understand the molecular basis of the antitumor activity of the mitomycins and make this knowledge applicable to new drug design and treatment protocols in cancer chemotherapy. First, the three adducts of MC and DNA will be examined for their location at specific DNA sequences, using footprinting techniques as well as Ba131 digestion as a tool. Effects of each adduct on DNA conformation will be assessed by examining the conformations of oligonucleotides modified at a single site by each of the three adducts, as models. Assay of adducts formed in cell cultures will be used as probe for (i) effect of intracellular 02 on crosslinking efficiency of MC, (ii) relative cytotoxicity of the three adducts, (iii) kinetics of removal of adducts by cellular repair. Excision repair of adducted DNA will be studied in an in vitro system, using single-site adducted DNA fragments. Two MC analogs, more effective than the parent MC will be examined for the molecular basis of their greater effectiveness by comparing their activation and DNA- reactivity with those of MC.