NAD AND PREVENTION OF MAMMARY CARCINOGENESIS

描述：拟议研究的目标是确定 烟酸摄入影响组织NAD水平的机制， 确定改变NAD水平对分子和细胞的影响， 对致癌物暴露和氧化应激的反应。 假设是 测试的是，次优烟酸营养状况导致细胞减少， NAD水平，导致恶性肿瘤的易感性， 环境对基因组的伤害 具体目标1是量化 烟酰胺、烟酸和色氨酸与细胞内 维持在原代培养中的人乳腺上皮（HME）细胞中的NAD含量 文化 HME细胞将从商业供应商处获得并培养 在含有不同量的烟酰胺和烟酸的确定培养基中， 酸 将确定细胞NAD和NADP的水平。 类似 将进行实验以确定色氨酸在多大程度上 能够在HME细胞中充当NAD前体。 具体目标二是 确定HME细胞所需的细胞内NAD含量， 显示出对致癌物诱导的DNA损伤或氧化的最佳反应， 应力 HME细胞，在导致不同的 浓度的细胞内NAD，将用以下任一种处理 N-甲基-N '-硝基-N-亚硝基胍（MNNG）或黄嘌呤/黄嘌呤氧化酶。 ADP-核糖聚合物代谢，p53转录水平，单个核细胞修复 DNA链断裂、姐妹染色单体交换、染色体畸变，以及 细胞存活将作为NAD含量的函数进行检查。 这些体外 这些研究将为设计未来的实验提供必要的信息 其中烟酸摄入量、 测定循环前体和乳腺上皮细胞NAD含量， 优化以限制致癌事件。

DESCRIPTION: The objectives of the proposed research are to determine the mechanism through which niacin intake affects tissue levels of NAD and to define the effects of altered NAD levels on the molecular and cellular responses to carcinogen exposure and oxidative stress. The hypothesis to be tested is that sub-optimal niacin nutriture results in reduced cellular levels of NAD, leading to a predisposition to malignancy following environmental insults to the genome. Specific Aim 1 is to quantify the relationship of nicotinamide, nicotinic acid and tryptophan to intracellular NAD content in human mammary epithelial (HME) cells maintained in primary culture. HME cells will be obtained from a commercial vendor and cultured in a defined medium containing varying amounts of nicotinamide and nicotinic acid. The levels of cellular NAD and NADP will be determined. Similar experiments will be performed to determine to what extent tryptophan is capable of serving as an NAD precursor in HME cells. Specific Aim 2 is to determine the intracellular NAD content required in order for HME cells to display an optimal response to carcinogen induced DNA damage or oxidative stress. HME cells, cultured under conditions that lead to varying concentrations of intracellular NAD, will be treated with either N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or xanthine/xanthine oxidase. ADP-ribose polymer metabolism, level of p53 transcription, repair of single strand DNA breaks, sister chromatid exchange, chromosomal aberrations, and cell survival will be examined as a function of NAD content. These in vitro studies will provide the information necessary to design future experiments in which the in vivo relationship between niacin intake, levels of circulating precursors, and breast epithelium NAD content determined and optimized to limit carcinogenic events.