Evaluation of DNA Cross-Linking by Aziridinomitosenes

描述(申请人提供)：一种与临床使用的抗癌药物丝裂霉素C有关的化合物-氮杂诺米松，最近被证明在非还原条件下形成DNA链间交联键。这种交联体的出现具有重要意义，原因有两个。首先，丝裂霉素C的抗肿瘤活性是形成罕见的链间DNA交联的结果。其次，氮杂环丁二烯以前被认为是形成毒性较小的DNA单加合物的唯一原因。有几个因素可能促进了这一以前未观察到的细胞毒性事件，包括位于C-6和C-7的醌环上的两个额外的亲电位点的存在。有证据表明，与丝裂霉素C一样，C-1和C-10亲电位点是形成交联物的关键，但交联物的分子结构尚不清楚。合成的氮杂环丁二烯的DNA交联剂的作用机理被认为是DNA在C-1氮杂环丙烷位上的第一次单烷基化，然后是第二次活化C-10位进行第二次烷基化。C-10活化事件被认为涉及对C-6或C-7原子的亲核攻击。这项建议旨在确定DNA-氮杂环氧丙烷链间交联物的分子结构，确定四个亲电位点的作用，并研究诱导交联物形成所需的物理性质。这项拟议的研究涉及三个具体目标：1)鉴定和制备相关的丝裂素类似物；2)表征丝裂素的还原电位、氮杂环丙烷的pKA和溶解稳定性；3)进行丝裂素衍生物对DNA烷基化的体外评估。研究完成后，将彻底了解与DNA烷基化能力有关的重要结构特征。这些信息将有助于澄清现有的文献观察，并使未来的研究能够利用最重要的特征。

DESCRIPTION (provided by applicant): An aziridinomitosene, a compound related to the clinically used anticancer agent mitomycin C, has recently been shown to form DNA interstrand cross-links under non-reductive conditions. The occurrence of the cross-link is significant for two reasons. First, mitomycin C's antitumor activity is the result of the formation of rare interstrand DNA cross-links. Second, aziridinomitosenes were previously thought to be responsible solely for formation of less toxic DNA monoadducts. Several factors may facilitate this previously unobserved cytotoxic event, including the presence of two additional electrophilic sites located on the quinone ring at C-6 and C-7. Evidence suggests that the C-1 and C-10 electrophilic sites are key to crosslink formation, as is the case with mitomycin C, but the molecular structure of the cross-link is not known. The mechanism of DNA cross-linking by the synthetic aziridinomitosene is hypothesized to involve first monoalkylation of DNA at the C-1 aziridine site followed by a second event that activates the C-10 site for a second alkylation. The C-10 activation event is proposed to involve nucleophilic attack at the C-6 or C-7 atoms. This proposal aims to identify the molecular structure of the DNA-aziridinomitosene interstrand cross-link, determine the role of the four electrophilic sites, and investigate the physical properties required to induce cross-link formation. The proposed research involves three specific aims: 1) identify and prepare relevant mitosene analogs; 2) characterize mitosenes with respect to reduction potential, aziridine nitrogen pKa, and solvolytic stability; 3) conduct an in vitro assessment of DNA alkylation by mitosene derivatives. Upon completion of the studies, a thorough understanding of the significant structural features with respect to DNA alkylating ability will be understood. The information will serve to clarify existing literature observations and allow for future studies that exploit the most significant characteristics.