Edelfosine and Miltefosine Effects on Lipid Raft Properties: Membrane Biophysics in Cell Death by Antitumor Lipids

Abstract

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.

Alkyl ether lipids, ion channels and lipid raft reorganization in cancer therapy

“…It is worth mentioning that recent data suggest that ohmline, unlike edelfosine (Ausili, et al, 2008;Castro, et al, 2013), rigidifies liposome and cell membrane (unpublished observations obtained using the fluorescent probe Laurdan that sense the fluidity of the lipid bilayer). Maybe differences on the polar group between A C C E P T E D M A N U S C R I P T…”

“…The affinity of edelfosine for cholesterol and lipid rafts (Ausili, et al, 2008;Busto, et al, 2008), altering the biophysical features of lipid raft domains in model membranes, increasing their thickness and fluidity (Ausili, et al, 2008;Castro, et al, 2013), and leading to the reorganization of these raft domains following edelfosine treatment, suggests that this AEL could constitute a paradigmatic and lead compound in this novel raftmediated therapy (Gajate & Mollinedo, 2011, 2014.…”

Miltefosine and BODIPY-labeled alkylphosphocholine with leishmanicidal activity: Aggregation properties and interaction with model membranes

“…Miltefosine (hexadecylphosphocholine, MT, see Fig. 1A) is a synthetic alkylphosphocholine originally developed for its antineoplastic properties, selectively accumulates in tumor cell membranes (8), but also presents a potent leishmanicidal activity (6,9,10). In recent years, MT afforded the first successful oral treatment against human visceral and cutaneous leishmaniasis, with mild secondary effects (11)(12)(13)(14), and it is indicated in India and Germany for that purpose since 2002, and administered as second line treatment for cutaneous leishmaniasis since 2005 in Colombia (15).…”

Effect of Erufosine on Membrane Lipid Order in Breast Cancer Cell Models

“…The observed effects vary depending on lipid composition and the investigated APL (e.g. Edelfosine or Miltefosine) and include: disorganization of Lo domains (11), moderate to significant increase of membrane fluidity (12,13) and stabilization of SM/cholesterol domains (14). More specifically, studies on Erucylphosphocholine (which is more similar to EPC3, due to the shared unsaturated acyl chain) indicate that this APL increases the fluidity of both cellular and model membranes (12), while weakening SM-cholesterol interactions (15).…”