We have discovered a new and specific cell-killing mechanism mediated by the selective uptake of the antitumor drug 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine (ET-18-OCH3, Edelfosine) into lipid rafts of tumor cells, followed by its coaggregation with Fas death receptor (also known as APO-1 or CD95) and recruitment of apoptotic molecules into Fas-enriched rafts. Drug sensitivity was dependent on drug uptake and Fas expression, regardless of the presence of other major death receptors, such as tumor necrosis factor (TNF) receptor 1 or TNF-related apoptosis-inducing ligand R2/DR5 in the target cell. Drug microinjection experiments in Fas-deficient and Fas-transfected cells unable to incorporate exogenous ET-18-OCH3 demonstrated that Fas was intracellularly activated. Partial deletion of the Fas intracellular domain prevented apoptosis. Unlike normal lymphocytes, leukemic T cells incorporated ET-18-OCH3 into rafts coaggregating with Fas and underwent apoptosis. Fas-associated death domain protein, procaspase-8, procaspase-10, c-Jun amino-terminal kinase, and Bid were recruited into rafts, linking Fas and mitochondrial signaling routes. Clustering of rafts was necessary but not sufficient for ET-18-OCH3–mediated cell death, with Fas being required as the apoptosis trigger. ET-18-OCH3–mediated apoptosis did not require sphingomyelinase activation. Normal cells, including human and rat hepatocytes, did not incorporate ET-18-OCH3 and were spared. This mechanism represents the first selective activation of Fas in tumor cells. Our data set a framework for the development of more targeted therapies leading to intracellular Fas activation and recruitment of downstream signaling molecules into Fas-enriched rafts.

Edelfosine (1-O-octadecyl-2-O-methyl-racglycero-3-phosphocholine) is an anti-tumour cell ether lipid with surface-active properties. Pure edelfosine can be dispersed in aqueous media in the form of micelles. One important, negative side effect of edelfosine is that it is highly haemolytic. In this paper, we show that edelfosine can be co-dispersed in water with certain lipids (particularly cholesterol, campesterol or β-sitosterol) so that it gives rise to liposomes. Surface pressure measurements demonstrate that edelfosine is slowly released from these liposomes. In liposomal form, edelfosine remains apoptogenic for a variety of leukemia cell lines, while its haemolytic effect is abolished. The phenomenon is explained on the basis of the complementarity of the molecular geometries of sterols and edelfosine.

Edelfosine (1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine; ) is an antitumor alkyl-lysophospholipid analog that binds lipid rafts, altering their protein composition (J Exp Med 200:353-365). Because L-selectin locates in lipid rafts and plays a crucial role in the recruitment of leukocytes into inflamed tissues, we hypothesized that edelfosine might affect inflammation by modulating L-selectin and inflammatory cell migration. Here, we have found that edelfosine inhibited neutrophil-endothelium interaction through L-selectin shedding. Oral treatment of edelfosine diminished inflammation in two murine animal models. Edelfosine showed a higher antiinflammatory effect than the nonsteroidal anti-inflammatory drug (NSAID) indomethacin in the bentonite mouse-paw edema model. Using a rat model of experimental colitis, edelfosine oral administration ameliorated the clinical and histopathologic severity of the inflammatory colitis with a dramatic decrease in mucosal damage and neutrophil infiltration. Colon sections from edelfosine-treated rats showed a remarkable reduction in ulcer formation, edema, and inflammatory cell infiltration. Edelfosine enhanced lipopolysaccharide-induced expression of anti-inflammatory interleukin-10 in mouse macrophages. Edelfosine oral treatment in rats, at doses 8-fold higher than those displaying anti-inflammatory action, lacked toxicity. Edelfosine treatment showed no any significant cardiotoxicity, hepatotoxicity or renal toxicity. Unlike NSAIDs, edelfosine did not inhibit prostaglandin E 2 synthesis in gastrointestinal mucosal biopsies, and no histologic alteration in gastrointestinal tract was detected after drug treatment. Thus, edelfosine shows a potent in vitro and in vivo anti-inflammatory activity while sparing gastric mucosa. Our data identify edelfosine as a novel anti-inflammatory drug by abating neutrophil infiltration through L-selectin shedding and may provide a new therapeutic approach for inflammatory bowel disease free from toxicity.