MECHANISM OF NITROSAMINE ALKYLATION OF DNA AND RNA

拟议研究的总体目标是研究 作为致癌物的β-氧化亚硝基二烷基胺。 新一任总 目的是研究β-氧化 亚硝基二丙胺衍生物导致肝DNA甲基化 给大鼠服用后。 我们将研究新陈代谢和DNA 通过亚硝基-2-羟丙基丙胺（NHPPA）进行甲基化，和 亚硝基-2-氧代丙基丙胺（NOPPA）使用大鼠肝脏制备物， 体外 特别是，我们将确定微粒体α-氧化 亚硝胺的释放导致甲基化中间体的产生。 我们 还将研究NHPPA的羟基基团的共轭作用 发挥其作为烷基化剂的活性。 第二个总目标 在明确定义的体外条件下，研究急性和 其他3种β-氧化衍生物的慢性效应 亚硝基二丙胺：亚硝基双（2-羟丙基）胺（BHP），亚硝基双 （2-氧代丙基）胺（BOP）和亚硝基双（2-羟丙基）（2-氧代丙基） 胺（HPOP）。 这些亚硝胺是叙利亚人的胰腺致癌物 仓鼠，影响导管和内分泌，但可能不影响外分泌 器官的一部分。 我们使用分离的细胞制剂将提供 独特的机会，研究反应和非反应组织内的 同样的器官。 我们已经开发了明确的文化体系， 仓鼠和大鼠（无反应种属）的内分泌胰腺 用于调查连续事件，包括功能和 形态学，亚硝胺处理后。 我们的最终目标是 确定BHP和BOP是否会导致DNA甲基化， 仓鼠胰腺细胞与大鼠中的NHPPA和NOPPA相同 肝脏，以及是否代谢的亚硝胺的最终 甲基化剂，以及随后甲基化的形成和持久性 DNA加合物，是亚硝胺敏感细胞特有的特性。

The overall aim of the proposed research is to study the mode of action of Beta-oxidized nitrosodialkylamines as carcinogens. The first general objective is to investigate the mechanism by which Beta-oxidized derivatives of nitrosodipropylamine lead to methylation of hepatic DNA following their administration to rats. We will study metabolism and DNA methylation by nitroso-2-hydroxypropylpropylamine (NHPPA) and nitroso-2-oxopropylpropylamine (NOPPA) using rat liver preparations in vitro. In particular, we will determine whether microsomal Alpha-oxidation of the nitrosamines leads to production of a methylating intermediate. We will also investigate the role conjugation of the hydroxyl group of NHPPA plays in its activity as an alkylating agent. The second general objective is to investigate, under well defined in vitro conditions, the acute and chronic effects of 3 other Beta-oxidized derivatives of nitrosodipropylamine: nitrosobis (2-hydroxypropyl) amine (BHP), nitrosobis (2-oxopropyl) amine (BOP), and nitrosobis (2-hydroxypropyl) (2-oxopropyl) amine (HPOP). These nitrosamines are pancreatic carcinogens for the Syrian hamster, and affect both ductular and endocrine, but probably not exocrine portions of the organ. Our use of isolated cell preparations will offer a unique opportunity to study responsive and non-responsive tissue within the same organ. The well-defined culture systems we have developed for the endocrine pancreas of the hamster and rat (non-responsive species) will be utilized to investigate the sequential events, both functional and morphological, following nitrosamine treatment. Our ultimate goal is to determine whether the mechanism of methylation of DNA by BHP and BOP in hamster pancreatic cells is the same as for NHPPA and NOPPA in the rat liver, and whether metabolism of the nitrosamines to the ultimate methylating agent, and subsequent formation and persistence of methylated DNA adducts, is a specific property of nitrosamine-susceptible cells.