Evaluation of DNA Cross-Linking by Aziridinomitosenes

描述（由申请人提供）：一种与临床使用的抗癌剂丝裂霉素C相关的化合物，aziridinomitotoxin，最近已显示在非还原条件下形成DNA链间交联。由于两个原因，交联的发生是重要的。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。第二，氮丙啶并有丝分裂素以前被认为是唯一负责形成毒性较小的DNA单加合物。有几个因素可能促进这种以前未观察到的细胞毒性事件，包括存在两个额外的亲电子位点位于醌环上的C-6和C-7。有证据表明，C-1和C-10亲电位点是交联形成的关键，丝裂霉素C也是如此，但交联的分子结构尚不清楚。通过合成的氮丙啶并咪唑啉的DNA交联的机制被假设为涉及在C-1氮丙啶位点处的DNA的第一单烷基化，随后是激活C-10位点进行第二烷基化的第二事件。提出C-10活化事件涉及在C-6或C-7原子处的亲核攻击。该提案旨在确定DNA-aziridinomitotoxin链间交联的分子结构，确定四个亲电位点的作用，并研究诱导交联形成所需的物理性质。拟开展的研究涉及三个具体目标：1）鉴定和制备相关的线粒体类似物; 2）表征线粒体的还原电位、氮丙啶氮pKa和溶剂分解稳定性; 3）通过线粒体衍生物进行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，并允许未来的研究，利用最显着的特点。

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.