Centro de Química Física-Molecular and Institute of Nanoscience and Nanotechnology, IST, Universidade Técnica de Lisboa , Av. Rovisco Pais, 1049-001 Lisboa, Portugal.
J Phys Chem B. 2013 Jul 3;117(26):7929-40. doi: 10.1021/jp401407d. Epub 2013 Jun 24.
Edelfosine (1-O-octadecyl-2-O-methyl-sn-glycero-phosphocholine) and miltefosine (hexadecylphosphocholine) are synthetic alkylphospholipids (ALPs) that are reported to selectively accumulate in tumor cell membranes, inducing Fas clustering and activation on lipid rafts, triggering apoptosis. However, the exact mechanism by which these lipids elicit these events is still not fully understood. Recent studies propose that their mode of action might be related with alterations of lipid rafts biophysical properties caused by these lipid drugs. To achieve a clear understanding of this mechanism, we studied the effects of pharmacologically relevant amounts of edelfosine and miltefosine in the properties of model and cellular membranes. The influence of these molecules on membrane order, lateral organization, and lipid rafts molar fraction and size were studied by steady-state and time-resolved fluorescence methods, Förster resonance energy transfer (FRET), confocal and fluorescence lifetime imaging microscopy (FLIM). We found that the global membrane and lipid rafts biophysical properties of both model and cellular membranes were not significantly affected by both the ALPs. Nonetheless, in model membranes, a mild increase in membrane fluidity induced by both alkyl lipids was detected, although this effect was more noticeable for edelfosine than miltefosine. This absence of drastic alterations shows for the first time that ALPs mode of action is unlikely to be directly linked to alterations of lipid rafts biophysical properties caused by these drugs. The biological implications of this result are discussed in the context of ALPs effects on lipid metabolism, mitochondria homeostasis modulation, and their relationship with tumor cell death.
埃德拉非尼（1-O-十八烷基-2-O-甲基-sn-甘油磷酸胆碱）和米替福新（十六烷基磷酸胆碱）是合成的烷基磷酸脂（ALP），据报道它们选择性地积聚在肿瘤细胞膜中，在脂筏上诱导 Fas 聚集和激活，引发细胞凋亡。然而，这些脂质引发这些事件的确切机制仍不完全清楚。最近的研究表明，它们的作用模式可能与这些脂质药物引起的脂筏生物物理性质的改变有关。为了清楚地理解这种机制，我们研究了药理相关浓度的埃德拉非尼和米替福新对模型和细胞膜性质的影响。通过稳态和时间分辨荧光法、荧光共振能量转移（FRET）、共焦和荧光寿命成像显微镜（FLIM）研究了这些分子对膜有序性、侧向组织以及脂筏摩尔分数和大小的影响。我们发现，这些 ALP 对模型膜和细胞膜的整体膜和脂筏生物物理性质没有显著影响。尽管如此，在模型膜中，检测到两种烷基脂质都轻微增加了膜流动性，尽管埃德拉非尼比米替福新更明显。这一没有剧烈变化的结果首次表明，ALP 的作用模式不太可能直接与这些药物引起的脂筏生物物理性质的改变有关。在讨论 ALP 对脂质代谢、线粒体稳态调节的影响及其与肿瘤细胞死亡的关系时，讨论了这一结果的生物学意义。
