LIPID HYDROPEROXIDE CYTOTOXICITY AND DETOXIFICATION

说明：脂质过氧化氢(LOOHs)具有潜在的危害性 活性氧攻击不饱和脂类产生的中间产物， 细胞膜中的磷脂(PLs)和胆固醇。单线态氧 ()派生的LOOHs引起了特别的兴趣，因为人们越来越关注 关于2介导光动力作用引起的皮肤光毒性 可见光辐射或长波紫外线辐射。有建议说 在细胞膜中产生或获得的LOOHs可以经历(I) 谷胱甘肽/硒过氧化物酶(GSH/GPX)介导的双电子还原 相对无害的酒精(解毒)或(Ii)铁介导的 单电子还原导致链式反应加剧 过氧化损伤，可能最终导致细胞凋亡或程序化 DEAT(毒性增强)。关于这些因素的信息有限 可能影响细胞内途径(I)和(II)之间的LOOH分配 暴露在过氧化应激下。这个问题将通过以下方式解决 以全面的方式研究这两条途径，首先使用 将胆固醇LOOHs和PLOOHs引入模型膜，然后 在不同的肿瘤细胞系中光产生的对应物。几种技术 在本实验室开发的将被使用，包括(I)高性能 汞阴极电化学法的高效液相色谱检测 [高效液相-EC(汞)]用于LOOH解毒的高灵敏度监测，以及 (Ii)薄层色谱-荧光成像放射检测(TLC-PI) 用于评估LOOH链起始力(CIP)，这是一个反映 “报告”类脂的氧化程度，例如[14C]胆固醇。这些 将使用方法来努力确定细胞内的变化 硒、铁或α-生育酚状态可能会影响LOOH的解毒作用 一方面，毒性增强导致细胞凋亡 另一个。这些研究旨在提供有关 具有重要生物学意义的LOOHs的动力学和细胞如何响应 1O2和其他活性物种引起的过氧化挑战。

DESCRIPTION: Lipid hydroperoxides (LOOHs) are potentially deleterious intermediates generated by activated oxygen attack on unsaturated lipids, phospholipids (PLs), and cholesterol in cell membranes. Singlet oxygen ()-derived LOOHs are of special interest because of the growing concern about cutaneous photoxicity resulting from 2-mediated photodynamic action of visible radiation or long wavelength ultraviolet radiation. It is proposed that LOOHs generated in or acquired by cell membranes can either undergo (i) glutathione/selenoperoxidase (GSH/GPX)-mediated two-electron reduction to relatively innocuous alcohols (detoxification) or (ii) iron-mediated one-electron reduction resulting in chain reactions that exacerbate peroxidative injury, possibly culminating in apoptotic or programmed cell deat (toxicity enhancement). Information is limited about the factors that might affect LOOH partitioning between pathways (i) and (ii) in a cell exposed to peroxidative stress. This question will be addressed by investigating both pathways in comprehensive fashion, first using cholesterol LOOHs and PLOOHs incorporated into model membranes and then photogenerated counterparts in various tumor cell lines. Several techniques developed in this laboratory will be used, including (i) high performance liquid chromatography with mercury cathode electrochemical detection [HPLC-EC(Hg)] for high-sensitivity monitorin of LOOH detoxification, and (ii) thin layer chromatography with phophorimaging radiodetection (TLC-PI) for assessing LOOH chain initiation potency (CIP), an index reflecting the degree of oxidation of a "reporter" lipid, e.g. [14C] cholesterol. These approaches will be used in an effort to ascertain how changes in cellular selenium, iron, or a-tocopherol status might affect LOOH detoxification on the one hand, and toxicity enhancement leading to apoptotic cell death on the other. The studies are intended to provide new information about the dynamics of biologically important LOOHs and how cells respond to peroxidative challenges imposed by 1O2 and other activated species.