Hui R, Everhart A L, Glasgow W C
Laboratory of Molecular Biophysics, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, NC 27709, USA.
J Lipid Res. 1997 Jan;38(1):49-60.
Epidermal growth factor (EGF) stimulates the lipoxygenase metabolism of linoleic acid to 13(S)-hydroxyoctadecadienoic acid (HODE) in Syrian hamster embryo (SHE) fibroblasts. 13(S)-HODE is a potent and specific enhancer of EGF-dependent DNA synthesis in normal phenotypic SHE cells (supB+), but is inactive in variant SHE cells that have lost tumor suppressor gene function (supB-). EGF activation of quiescent SHE cells results in increased levels of 13-HODE esterified in cellular phospholipid and triglyceride. Steric analyses suggest that this metabolite is generated in part by direct oxygenation of membrane lipids by an n-6 lipoxygenase. In studies on the uptake and mobilization of 13-HODE in SHE cells, we observed EGF to stimulate a time- and dose-dependent incorporation and reacylation of the mono-hydroxy linoleate metabolite. The level of 13-HODE uptake in supB+ cells is twice that of supB-. Among classes of phospholipids, radiolabeled 13-HODE is esterified predominantly into phosphatidylcholine and this distribution pattern is similar for both SHE cell lines. Pretreatment of cells with the tyrosine kinase inhibitor methyl-2,5-dihydroxycinnamate blocks EGF-stimulated HODE incorporation. Inhibition of tyrosine phosphatase activity with vanadate potentiates HODE uptake in supB+ but not supB- cells. Moreover, activation of protein kinase C with phorbol ester stimulates HODE incorporation in the supB+ line only. The differential effects of EGF on 13-HODE uptake and mobilization in supB+ and supB- cells appear to be related to loss of the tumor suppressor phenotype. EGF-stimulated generation of esterified 13-HODE may be an important biological process in determining the mechanism and site of HODE interaction with the mitogenic signaling pathway.
表皮生长因子（EGF）可刺激叙利亚仓鼠胚胎（SHE）成纤维细胞中，亚油酸的脂氧合酶代谢生成13(S)-羟基十八碳二烯酸（HODE）。13(S)-HODE是正常表型SHE细胞（supB+）中EGF依赖性DNA合成的强效特异性增强剂，但在已丧失肿瘤抑制基因功能的SHE变异细胞（supB-）中无活性。静止的SHE细胞经EGF激活后，细胞磷脂和甘油三酯中酯化的13-HODE水平会升高。立体分析表明，这种代谢产物部分是由n-6脂氧合酶对膜脂的直接氧化产生的。在对SHE细胞中13-HODE的摄取和转运的研究中，我们观察到EGF可刺激单羟基亚油酸酯代谢产物的时间和剂量依赖性掺入及再酰化。supB+细胞中13-HODE的摄取水平是supB-细胞的两倍。在各类磷脂中，放射性标记的13-HODE主要酯化为磷脂酰胆碱，两种SHE细胞系的这种分布模式相似。用酪氨酸激酶抑制剂甲基-2,5-二羟基肉桂酸预处理细胞可阻断EGF刺激的HODE掺入。用钒酸盐抑制酪氨酸磷酸酶活性可增强supB+细胞而非supB-细胞对HODE的摄取。此外，佛波酯激活蛋白激酶C仅刺激supB+细胞系中HODE的掺入。EGF对supB+和supB-细胞中13-HODE摄取和转运的不同影响似乎与肿瘤抑制表型的丧失有关。EGF刺激生成酯化的13-HODE可能是确定HODE与促有丝分裂信号通路相互作用机制和位点的重要生物学过程。
