GENOTOXICITY OF DNA-DIRECTED ANTINEOPLASTIC AGENTS

在癌症化疗中使用的许多最有效的药物是DNA- 破坏性因素。然而，接受治疗的长期幸存者至少要接受 其中一些药物开发的风险大大增加。 第二，无关的恶性肿瘤，可能是诱变剂的结果 这些药物的效果。拟议研究的最终目标是 了解某些抗肿瘤药物发挥作用的机制 致突变和致癌作用，以便于选择 以及开发更有效、致癌性更低的化疗药物 代理和协议。对于导致DNA双链断裂的药物， 包括拟放射药物博莱霉素和新卡西宁，以及 拓扑异构酶II抑制剂m-AMSA与替尼平苷的关系 在双链断裂修复和缺失突变之间将 调查过了。限定的修复基板，结合了一个独特的位置- 特定的双链断裂，具有特定的末端特征 药物诱导的中断，将被构建。这些底物将是 导入各种哺乳动物和其他真核细胞，并修复 产品将被回收和分析，以尝试开发模型以 解释双链断裂是如何修复的，如何堵塞 是否处理了终端，以及是否有任何特定的阻塞终端被 尤其容易在修复过程中造成删除。为了确定 在内源性基因、诱导的突变中是否发生类似的修复事件 通过这些相同的药物，CHO细胞中的aprt基因将被测序。 对于双官能团烷基化试剂马法兰来说，它已经强烈地 与第二种恶性肿瘤相关的序列已在 CHO/APRT和穿梭载体系统中，这是药物的频繁部位- 诱发碱基替换突变。既有单功能也有双功能 药物在这些序列上诱导的加合物将按顺序进行鉴定 为了确定是否在这些位置特别形成了任何加合物， 以及这些加合物是否与突变有关。光谱分析 由马法兰的单功能类似物诱导的突变 在CHO/APRT和穿梭载体系统中确定，以便 确定单功能和双功能的相对重要性 诱变中的烷基化作用。对于所有正在研究的药物，分子 将使用计算机图形学建模来尝试解释 结构术语每种药物引起的DNA损伤的类型。

Many of the most effective drugs used in cancer chemotherapy are DNA- damaging agents. However, long-term survivors of treatment with at least some of these drugs have a substantially increased risk of developing second, unrelated malignancies, presumably as a result of the mutagenic effects of these drugs. The ultimate goal of the proposed studies is to understand the mechanisms by which certain antitumor drugs exert their mutagenic and carcinogenic effects, in order to facilitate the selection and development of more effective and less carcinogenic chemotherapeutic agents and protocols. For drugs which induce DNA double-strand breaks, including the radiomimetics bleomycin and neocarzinostatin and the topoisomerase II inhibitors m-AMSA and teniposide, the relationship between double-strand break repair and deletion mutagenesis will be investigated. Defined repair substrates which incorporate a unique site- specific double-strand break, with termini characteristic of particular drug-induced breaks, will be constructed. These substrates will be introduced into various mammalian and other eukaryotic cells, and repaired products will be recovered and analyzed in an attempt to develop models to explain how the double-strand breaks were repaired, how the blocked termini were processed, and whether any specific blocked termini were particularly prone to cause deletions during repair. In order to determine whether similar repair events occur in endogenous genes, mutations induced by these same drugs in the aprt gene in CHO cells will be sequenced. For the bifunctional alkylating agent melphalan, which has been strongly associated with second malignancies, sequences have been identified in CHO/aprt and in shuttle vector systems which are frequent sites of drug- induced base substitutions mutations. Both monofunctional and bifunctional adducts induced by the drug at these sequences will be identified in order to determine whether any adducts are specifically formed at these sites, and whether these adducts can be implicated in mutagenesis. Spectra of mutations induced by a monofunctional analogue of melphalan will be determined in CHO/aprt and in a shuttle vector system in order to determine the relative importance of monofunctional and bifunctional alkylation in mutagenesis. For all the drugs being studied, molecular computer graphics modeling will be employed in an attempt to explain in structural terms the types of DNA damage induced by each drug.