Evaluation of DNA Cross-Linking by Aziridinomitosenes

描述（由申请人提供）：一种aziridinomitosene，一种与临床使用的抗癌药物丝裂霉素C相关的化合物，最近被证明在非还原条件下形成DNA链间交联。交联的发生有两个重要的原因。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，以前认为叠氮二烯核苷只负责形成毒性较小的DNA单加合物。有几个因素可能促进了这种以前未观察到的细胞毒性事件，包括位于醌环C-6和C-7上的两个附加亲电位点的存在。有证据表明，C-1和C-10亲电位点是形成交联的关键，丝裂霉素C也是如此，但交联的分子结构尚不清楚。假设合成叠氮二烯的DNA交联机制涉及在C-1叠氮嘧啶位点的DNA的第一次单烷基化，然后是激活C-10位点的第二次烷基化的第二个事件。C-10活化事件被认为涉及到对C-6或C-7原子的亲核攻击。本研究旨在确定dna -叠氮二烯烯链交联的分子结构，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。拟开展的研究包括三个具体目标：1)鉴定和制备相关的线粒体类似物；2)表征有丝分裂体的还原电位、氮偶氮pKa和溶解稳定性；3)线粒体衍生物对DNA烷基化的体外评价。在研究完成后，将对DNA烷基化能力的重要结构特征有一个透彻的了解。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.