Nitrosamine Carcinogenesis

描述：本提案的长期目标是了解化学 介导生物效应的关键活性中间体 致突变和致癌的亚硝胺，以及亚硝胺和 反应性中间结构，影响其生物活性。 亚硝胺是一大类结构多样的致癌物质， 人体暴露量很大。传统上， 亚硝胺被归因于P450酶的代谢活化， 产生不稳定的α-羟基亚硝胺，分解为重氮酸。这些 产生重氮离子和碳阳离子，使DNA烷基化，最终产生 突变。这对于甲基和乙基取代的化合物是公认的， 但相比之下，更复杂的亚硝胺的活性可能仅部分或 经典途径对此描述不佳。本建议旨在：a）界定 更复杂的α-羟基亚硝胺的非经典水化学; 和B）确定形成的程度和生物学意义， 关于人聚合酶相互作用和人诱变，支链的 DNA的烷基加合物。具体目标有5个：1）综合研究 α-羟基亚硝胺及其衍生物的水化学 N-亚硝基吗啉、亚硝基去甲烟碱和亚硝基假木贼碱; 2） A、G和T碱基的异丙基加合物的形成的定量 异丙基或正丙基衍生的异丙基阳离子与DNA的反应 3）异丙基化环外氧和氮DNA的合成 碱基亚磷酰胺和掺入合成寡核苷酸 在确定的位置上含有加合物; 4）编码和延伸分析 与人DNA聚合酶的加合物相对;和5）测定 在人成纤维细胞中， 加合的寡核苷酸，通过穿梭质粒pLS 189。

DESCRIPTION: The long-term goal of this proposal is to understand the chemistry of the key reactive intermediates that mediate the biological effects of mutagenic and carcinogenic nitrosamines and the effects of nitrosamine and reactive intermediate structure that impact their biological activity. Nitrosamines are a large class of structurally diverse carcinogens to which there is significant human exposure. Classically, the deleterious effects of nitrosamines have been ascribed to metabolic activation by P450 enzymes that yield unstable alpha-hydroxynitrosamines that decompose to diazoic acids. These yield diazonium ions and carbocations that alkylate DNA, ultimately producing mutations. This is well established for methyl and ethyl-substituted compounds, but in contrast the activity of more complex nitrosamines may be only partly or poorly described by the classical pathway. This proposal seeks to: a) delineate the non classical aqueous chemistry of more complex alpha-hydroxynitroamines; and b) to determine the extent of formation and biological implications, with respect to human polymerase interactions and human mutagenesis, of branched alkyl group adducts of DNA. There are 5 specific aims: 1) synthesis and study of the aqueous chemistry of alpha hydroxynitrosamines and related derivatives of N-nitrosomorpholine, nitrosonornicotine, and nitrosoanabasine; 2) quantitation of the formation of isopropyl adducts of A, G and T bases from reactions with DNA of isopropyl cations derived from the iso-propyl or n-propyl diazonium ions; 3) synthesis of isopropylated exocyclic oxygen and nitrogen DNA base phosphoramidites and incorporation into synthetic oligonucleotides containing adducts at defined positions; 4) analysis of coding and extension opposite the adducts by human DNA polymerases; and 5) determination of the frequency and spectrum of mutations in human fibroblasts arising from the adducted oligos, by means of the shuttle plasmid pLS189.