DNA Adducts of Styrene and Other Vinyl Monomers

描述(申请人提供)：用于生产橡胶和塑料的苯乙烯和丁二烯与人类癌症的病因学有关。丁二烯被美国环保局归类为“吸入致癌物质”，被国家环保局归类为“已知的人类致癌物质”。长期职业接触苯乙烯和丁二烯混合物与罹患白血病的风险相关。该项目将研究丁二烯诱导突变的病因学，开发丁二烯环氧化物产生的DNA加合物的结构-活性关系，并与人类遗传毒性有关。第一个目标将结合核磁共振、结晶学和生化方法来检测N1-脱氧腺苷烷基化产物的脱氨基产生的N1-脱氧肌苷加合物。我们建议Y-家族POL I利用dL的Hoogsteen面作为模板，允许掺入质子化dCTP或dATP。第二个目标将使用核磁共振和结晶学方法来研究丁二烯单环氧化物的立体异构体N3-Du加合物，它是由N3-DC加合物脱氨而产生的。我们认为，它们不经历糖基键的旋转，进入syn构象，从而导致根本不同的生物学和突变结果。第三个目标将使用核磁共振、生化和定点突变来检查因接触丁二烯环氧化物而产生的N7-DG加合物。重点介绍N7-DG加成与丁二烯二环氧化物形成链间和链内交联物的关系；这取决于DNA序列和双环氧化物立体化学。链间交联以5‘-GNC-3’序列形式形成。我们认为，N7-DG丁二烯二醇单加合物的取向取决于立体化学，即二元醇环氧化物的链间和链内交联方向不同。将研究N7-DG Fapy重排产物的化学、突变光谱和复制旁路。总体而言，我们将描述N1-d1和N3-杜丁二烯加合物诱导突变的机制(S)，以及为什么特异性聚合酶(S)介导病变旁路。我们将深入了解丁二烯二环氧化合物的DNA交联化学。将深入了解丁二烯N7-DG Fapy损伤的化学、它们的生物过程和它们的结构。这对于理解职业暴露在苯乙烯和丁二烯混合物中如何导致人类遗传毒性和癌症病因学是至关重要的。

DESCRIPTION (provided by applicant): Styrene and butadiene, used in the production of rubber and plastics, are implicated in the etiology of human cancer. Butadiene is classified by the USEPA as "carcinogenic to humans by inhalation", by the NTP as a "known human carcinogen". Chronic occupational exposures to mixtures of styrene and butadiene correlate with risk for leukemias. This project will examine the etiology of butadiene-induced mutagenesis, developing structure-activity relationships for DNA adducts arising from butadiene epoxides and associated with human genotoxicity. The first aim will combine NMR, crystallography, and biochemical approaches to examine N1- deoxyinosine adducts arising from deamination of N1-deoxyadenosine alkylation products. We propose a role for Y-family Pol i utilizing the Hoogsteen face of dl for templating, allowing incorporation of protonated dCTP or dATP. The second aim will employ NMR and crystallographic approaches to examine stereoisomeric N3-dU adducts of butadiene monoepoxide, which arise from deamination of N3-dC adducts. We propose that they do not undergo rotation about the glycosyl bond, into the syn conformation, thus leading to fundamentally different biological and mutagenic outcomes. The third aim will use NMR, biochemical, and site-specific mutagenesis to examine N7-dG adducts arising from exposures to butadiene epoxides. Emphasis will be placed on relationships of N7-dG adduction to the formation of interstrand and intrastrand crosslinks by butadiene diepoxide; this depends upon DNA sequence and diepoxide stereochemistry. Interstrand crosslinks form in 5'-GNC-3' sequences. We propose that the orientations of N7-dG butadiene diol epoxide mono-adducts depend upon stereochemistry, differentially orienting the diol epoxides for interstrand vs. intrastrand crosslinking. The chemistry, mutational spectra, and replication bypass of N7-dG FAPy re-arrangement products will be examined. Overall, we will delineate mechanism(s) by which N1-dl and N3-dU butadiene adducts induce mutations, and why specific polymerase(s) mediate lesion bypass. Insight will be gained into DNA crosslinking chemistry of butadiene diepoxides. Insight will be gained into the chemistry of butadiene N7-dG FAPy lesions, their biological processing, and their structures. This is essential to understanding how occupational exposures to mixtures of styrene and butadiene contribute to human genotoxicity and cancer etiology.