Morad Samy A F, Ryan Terence E, Neufer P Darrell, Zeczycki Tonya N, Davis Traci S, MacDougall Matthew R, Fox Todd E, Tan Su-Fern, Feith David J, Loughran Thomas P, Kester Mark, Claxton David F, Barth Brian M, Deering Tye G, Cabot Myles C
Department of Biochemistry and Molecular Biology East Carolina Diabetes and Obesity Institute, Brody School of Medicine, East Carolina University, Greenville, NC.
Cancer Center, Division of Hematology Oncology, Department of Medicine Department of Pharmacology, University of Virginia, Charlottesville, VA.
J Lipid Res. 2016 Jul;57(7):1231-42. doi: 10.1194/jlr.M067389. Epub 2016 May 2.
The objective of our study was to determine the mechanism of action of the short-chain ceramide analog, C6-ceramide, and the breast cancer drug, tamoxifen, which we show coactively depress viability and induce apoptosis in human acute myelogenous leukemia cells. Exposure to the C6-ceramide-tamoxifen combination elicited decreases in mitochondrial membrane potential and complex I respiration, increases in reactive oxygen species (ROS), and release of mitochondrial proapoptotic proteins. Decreases in ATP levels, reduced glycolytic capacity, and reduced expression of inhibitors of apoptosis proteins also resulted. Cytotoxicity of the drug combination was mitigated by exposure to antioxidant. Cells metabolized C6-ceramide by glycosylation and hydrolysis, the latter leading to increases in long-chain ceramides. Tamoxifen potently blocked glycosylation of C6-ceramide and long-chain ceramides. N-desmethyltamoxifen, a poor antiestrogen and the major tamoxifen metabolite in humans, was also effective with C6-ceramide, indicating that traditional antiestrogen pathways are not involved in cellular responses. We conclude that cell death is driven by mitochondrial targeting and ROS generation and that tamoxifen enhances the ceramide effect by blocking its metabolism. As depletion of ATP and targeting the "Warburg effect" represent dynamic metabolic insult, this ceramide-containing combination may be of utility in the treatment of leukemia and other cancers.
我们研究的目的是确定短链神经酰胺类似物C6-神经酰胺和乳腺癌药物他莫昔芬的作用机制，我们发现它们共同降低人急性髓性白血病细胞的活力并诱导其凋亡。暴露于C6-神经酰胺-他莫昔芬组合会导致线粒体膜电位和复合体I呼吸作用降低，活性氧（ROS）增加，以及线粒体促凋亡蛋白的释放。ATP水平降低、糖酵解能力下降以及凋亡蛋白抑制剂的表达减少也随之出现。药物组合的细胞毒性通过暴露于抗氧化剂而减轻。细胞通过糖基化和水解代谢C6-神经酰胺，后者导致长链神经酰胺增加。他莫昔芬强烈阻断C6-神经酰胺和长链神经酰胺的糖基化。N-去甲基他莫昔芬是一种较弱的抗雌激素药物，也是人体中他莫昔芬的主要代谢产物，它与C6-神经酰胺一起使用时也有效，这表明传统的抗雌激素途径不参与细胞反应。我们得出结论，细胞死亡是由线粒体靶向和ROS生成驱动的，并且他莫昔芬通过阻断其代谢增强了神经酰胺的作用。由于ATP的消耗和对“瓦伯格效应”的靶向代表了动态代谢损伤，这种含神经酰胺的组合可能在白血病和其他癌症的治疗中有用。
