Induction of ceramide-mediated apoptosis by the anticancer phospholipid analog, hexadecylphosphocholine
Induction of ceramide-mediated apoptosis by the anticancer phospholipid analog, hexadecylphosphocholine
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DOI：
10.1074/jbc.273.18.11025
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发表时间：
1998-05-01
影响因子：
4.8
通讯作者：
Geilen, CC
中科院分区：
文献类型：
--
作者：
Wieder, T;Orfanos, CE;Geilen, CC
一种新型的抗增殖磷脂类似物，十六烷基磷脂（HePC），已经被证明可以抑制肿瘤生长，目前被用于治疗乳腺癌的皮肤转移。虽然已经提出了HePC的几个细胞靶点，如蛋白激酶C和CTP：磷脂酰转移酶，但HePC诱导的抗癌活性机制尚不清楚，考虑到HePC的抗增殖作用与抑制磷脂酰胆碱的生物合成有关，而磷脂酰胆碱的生物合成与鞘磷脂的生物合成紧密耦合。我们检验了用抗癌药物治疗细胞导致细胞神经酰胺增加并随后导致细胞凋亡的假设。在本研究中，我们发现25 μ mol/l的HePC诱导细胞凋亡，在进一步的实验中，我们发现HePC抑制放射性标记的胆碱并入磷脂酰胆碱，并在稍后的时间点并入鞘磷脂。用放射性标记的丝氨酸对脂质骨干进行代谢标记证实了这一点，结果表明HePC使丝氨酸并入鞘磷脂的比例降低了35%，同时使丝氨酸并入神经酰胺的比例增加了70%。神经酰胺含量的测定显示，hepc处理的细胞与对照组相比增加了53%。根据神经酰胺水平升高可能是HePC代谢作用与其促凋亡特性之间缺失环节的假设，HePC诱导的细胞凋亡被神经酰胺合成抑制剂福马菌素B-1阻断。此外，我们发现膜渗透性神经酰胺增加了HePC的凋亡作用。
The prototype of a new class of antiproliferative phospholipid analogs, hexadecylphosphocholine (HePC), has been shown to inhibit tumor growth and is currently used for the treatment of cutaneous metastases of mammary carcinomas. Although several cellular targets of HePC, e.g. protein kinase C and CTP:phosphocholine cytidylyltransferase, have been proposed, the mechanisms of HePC-induced anticancer activity are still unclear, Considering that the antiproliferative effect of HePC correlates with inhibition of phosphatidylcholine biosynthesis, which is tightly coupled to sphingomyelin biosynthesis, we tested the hypothesis that treatment of cells with the anticancer drug leads to increased cellular ceramide and subsequently to apoptotic cell death. In the present study, we showed that 25 mu mol/liter HePC induced apoptosis, In further experiments, we demonstrated that HePC inhibited the incorporation of radio-labeled choline into phosphatidylcholine and at a later time point into sphingomyelin. This was confirmed by metabolic labeling of the lipid backbone using radio-labeled serine, and it was shown that HePC decreased the incorporation of serine into sphingomyelin by 35% and simultaneously increased the incorporation of serine into ceramide by 70%. Determination of the amount of ceramide revealed an increase of 53% in HePC-treated cells compared with controls. In accordance with the hypothesis that elevated ceramide levels may be the missing link between the metabolic effects of HePC and its proapoptotic properties, HePC-induced apoptosis was blocked by fumonisin B-1, an inhibitor of ceramide synthesis, Furthermore, we found that membrane-permeable ceramides additively increased the apoptotic effect of HePC.