LIPID HYDROPEROXIDE CYTOTOXICITY AND DETOXIFICATION

描述：脂质氢过氧化物（LOOH）可能有害 由活性氧攻击不饱和脂质产生的中间体， 磷脂（PL）和胆固醇。 单线态氧 （）-衍生的LOOH特别令人感兴趣，因为人们越来越关注 关于由2-介导的光动力作用引起的皮肤光毒性， 可见光辐射或长波长紫外线辐射。 拟 在细胞膜中产生或获得的LOOH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， 相对无害的醇（解毒）或（ii）铁介导的 单电子还原导致链式反应， 过氧化损伤，可能最终导致凋亡或程序化细胞 毒性增强（Toxicity Enhancement）。 关于造成这种情况的因素的信息有限， 可能影响细胞中途径（i）和（ii）之间的LOOH分配 暴露在过氧化应激中 这一问题将由 全面调查这两种途径，首先使用 胆固醇LOOH和PLOOH掺入模型膜，然后 在各种肿瘤细胞系中的光生对应物。 几种技术 将使用该实验室开发的，包括（i）高性能 液相色谱-汞阴极电化学检测 [HPLC-EC（Hg）]用于LOOH解毒的高灵敏度监测，以及 (ii)薄层层析-荧光成像放射性检测 为了评估LOOH链起始效力（CIP），一个反映 “报告”脂质（例如[14 C]胆固醇）的氧化程度。 这些 方法将被用于努力确定细胞的变化， 硒、铁或α-生育酚状态可能影响LOOH解毒， 一方面，毒性增强导致细胞凋亡， 另一 这些研究旨在提供有关 生物学上重要的LOOH的动力学以及细胞如何响应 1 O2和其他活化物质带来的过氧化挑战。

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.