INHIBITION OF CHEMICAL TRANSFORMATION BY ASPIRIN

我们将继续我们早期的发现，阿司匹林抑制晚期的 C3H/10T1/2细胞的化学转化。 我们将特别在 确定阿司匹林抑制化学转化的机制， C3H/10T1/2细胞，以及是否有拟南芥素或其他类花生酸发挥作用。 在C3H/10T1/2细胞化学转化的晚期阶段中的作用。 首先，我们将严格通过HPLC和RIA方法确定是否 MCA的转化浓度引起花生四烯酸释放， 在C3H/10T1/2细胞中的洋地黄素和其它类花生酸的生物合成。 然后，我们将确定前列腺素或白三烯的水平 花生四烯酸代谢的代谢物在细胞中减少 用1Mu/ml的3-甲基氯蒽转化，然后加入20 μ g/ml的阿司匹林对细胞的作用，我们以前发现它可以显著抑制 化学转化 我们将用C3H/10T1/2细胞的抑制剂处理C3H/10T1/2细胞， 花生四烯酸释放抑制剂，如地塞米松， 环氧合酶，如阿司匹林、吲哚美辛和氟比洛芬， 脂氧合酶活性抑制剂（有些还抑制环氧合酶 活性）如5，6脱氢-花生四烯酸，去甲二氢瓜尿酸， 和BW 755C，并确定在类花生酸生物合成途径中， 对转化的抑制作用最大。 这将有助于我们 集中在最少数量的类二十烷酸代谢物进行检查， 化学转化的假定增强剂。 然后我们将研究 阿司匹林介导的部分纯化环氧合酶在细胞中的表达 C3H/10T1/2细胞的组分。 我们还将确定抑制是否 MCA处理C3H/10T1/2细胞后， 阿司匹林治疗与抑制化学转化相关 环氧合酶抑制剂阿司匹林和吲哚美辛。 其次，我们将添加花生四烯酸代谢物，这两种代谢物都是通过 环氧合酶，也通过脂氧合酶途径，C3 H/10 T1/2细胞 用起始浓度为0.1 μ g/ml的MCA处理，并测定 这些代谢物是否增强C3H/10T1/2细胞的转化， 用1 μ g/ml的 阿司匹林 在所有转化试验中，我们还将并行运行我们的 先前开发的测定哇巴因突变诱导的方法 以确定是否对增强或抑制 转换被类似的增强或抑制， 碱基置换突变

We will pursue our earlier findings that aspirin inhibits late stages of chemical transformation of C3H/10T1/2 cells. We will specifically in determine mechanisms by which aspirin inhibits chemical transformation of C3H/10T1/2 cells and whether prostaglandins or other eicosanoids play a role in late stages of chemical transformation of C3H/10T1/2 cells. Firstly, we will rigorously by HPLC and RIA methodologies determine whether transforming concentrations of MCA cause arachidonic acid release and biosynthesis of prostaglandins and other eicosanoids in C3H/10T1/2 cells. Then, we will determine whether levels of prostaglandin or leukotriene metabolites of arachidonic acid metabolism are reduced in cells undergoing transformation by 1Mu/ml 3-methylchlanthrene following addition of 20 Mug/ml of aspirin to cells, which we previously found markedly inhibits chemical transformation. We will treat C3H/10T1/2 cells with inhibitors of arachidoinic acid release, such as dexamethasone, with inhibitors of cyclooxygenase, such as aspirin, indomethacin, and flurbiprofen, with inhibitors of lipoxygenase acitivity (some also inhibit cyclooxygenase activity) such as 5,6 dehydro-arachidonic acid, nordihydroguariuretic acid, and BW 755C, and determine where in the eicosanoid biosynthetic pathway the greatest inhibitory effect is exerted on transformation. This will help us focus on the fewest number of eicosanoid metabolites to be examined as putative enhancers of chemcial transformation. We will then study aspirin-mediated inhibiton of partially purified cyclooxygenase in cell fractions of C3H/10T1/2 cells. We will also determine whether inhibition of cyclooxygenase activity in MCA-treated C3H/10T1/2 cells subsequently treated with aspirin correlates with inhibition of chemical transformation by the cyclooxygenase inhibitors aspirin and Indomethacin. Secondly, we will add arachidonic acid metabolites, both those formed via cyclooxygenase and also via the lipoxygenase pathways, to C3H/10T1/2 cells treated with an initiating concentration of MCA, 0.1 Mug/ml, and determine whether these metabolites enhance the transformation of C3H/10T1/2 cells or reverse inhibition of transformation incells treated with 1 Mug/ml of aspirin. In all transformation assays, we will also run in parallel our previously developed assay measuring induction of mutation to ouabain resistance to determine whether effects on enhancement of or inhibition of transformation are paralleled by similar enhancements or inhibitions of base substitution mutations.