Kim A T, Sarafian T A, Shau H
Division of Surgical Oncology, UCLA School of Medicine, Los Angeles, California 90095, USA.
Toxicol Appl Pharmacol. 1997 Nov;147(1):135-42. doi: 10.1006/taap.1997.8270.
Natural killer-enhancing factor B (NKEF-B) belongs to a highly conserved family of recently discovered antioxidants. The role of NKEF-B as an antioxidant was demonstrated by its protection of transfected cells to oxidative damage by hydrogen peroxide. To further characterize the antioxidant properties of NKEF-B, we compared the sensitivity of a human endothelial cell line ECV304 and its transfectant, B/1 that hyperexpresses NKEF-B, to various oxidants. In addition, we investigated the changes in the expression of NKEF-B mRNA upon oxidative stress. We found that B/1 was significantly more resistant than the control cells to the oxidative stresses caused by t-butyl hydroperoxide (t-BHP) and methyl mercury (MeHg). In contrast, there was no difference in the sensitivity of B/1 and the control cells to sulfhydryl reactive agents, diethyl maleate and diamide. B/1 was also as sensitive as the control cells to buthionine sulfoximine. The expression of NKEF-B mRNA was induced when the parental cell line ECV304 was treated with 2 mm HP. The induction reached a maximum level around 2 hr and decreased to the basal level around 4 hr. NKEF-A mRNA was not induced by HP. These results demonstrate antioxidant activities of NKEF-B toward prooxidants such as alkyl hydroperoxide and MeHg. Together with its antioxidant activity, the induction of NKEF-B by HP indicates that NKEF-B is an important oxidative stress protein providing protection against a variety of xenobiotic toxic agents.
自然杀伤细胞增强因子B（NKEF-B）属于最近发现的高度保守的抗氧化剂家族。NKEF-B作为抗氧化剂的作用通过其对转染细胞免受过氧化氢氧化损伤的保护作用得以证明。为了进一步表征NKEF-B的抗氧化特性，我们比较了人内皮细胞系ECV304及其过表达NKEF-B的转染子B/1对各种氧化剂的敏感性。此外，我们研究了氧化应激时NKEF-B mRNA表达的变化。我们发现B/1比对照细胞对叔丁基过氧化氢（t-BHP）和甲基汞（MeHg）引起的氧化应激具有显著更高的抗性。相反，B/1和对照细胞对巯基反应剂马来酸二乙酯和二酰胺的敏感性没有差异。B/1对丁硫氨酸亚砜胺也与对照细胞一样敏感。当亲本细胞系ECV304用2 mM过氧化氢（HP）处理时，NKEF-B mRNA的表达被诱导。诱导在约2小时达到最高水平，并在约4小时降至基础水平。HP未诱导NKEF-A mRNA。这些结果证明了NKEF-B对诸如烷基过氧化氢和MeHg等促氧化剂的抗氧化活性。连同其抗氧化活性，HP对NKEF-B的诱导表明NKEF-B是一种重要的氧化应激蛋白，可提供针对多种外源性有毒剂的保护作用。
