Statistical analyses were performed through the use of Student’s t-test for combined samples or nonparametric Anova test. between ganglioside GM3, loaded in lymphoid cells, and DR4 was recognized. This association was negligible in every non-transformed cells and was linked to TRAIL susceptibility of cancer cells strictly. Oddly enough, lipid raft disruptor methyl-beta-cyclodextrin abrogated this susceptibility, whereas the chemotherapic medication perifosine, which induced the recruitment of Path into lipid microdomains, improved TRAIL-induced apoptosis. Appropriately, in examples from individuals with B-chronic lymphocytic leukemia, the constitutive embedding of DR4 in lipid microdomains was connected with cell loss of life susceptibility, whereas its exclusion was connected with Path resistance. These outcomes provide a crucial mechanism for TRAIL sensitivity in B-cell malignances: the association, within lipid microdomains, of DR4 but not DR5, with a specific ganglioside, that is the monosialoganglioside GM3. On these bases we suggest Carmustine that lipid microdomains could exert a catalytic role for DR4-mediated cell death and that an quantitative FRET analysis could be predictive of cancer cell sensitivity to TRAIL. Keywords: cancer, hematology, TRAIL, death receptors, lipid rafts, apoptosis In the course of years, several attempts have been made in order to develop therapeutic strategies aimed at the induction of cell death program, that is, apoptosis. Unfortunately, clinical Carmustine benefits deriving from this approach appeared as limited. Instead, more recently, the use of biological agents as well as of the so-called Carmustine molecularly targeted Mouse monoclonal to IKBKB therapy lead to some promising clinical result. In particular, agents capable of specifically modulating cell signals leading to apoptosis of cancer cells sparing non-tumor cell targets gained the attention of physicians and several studies have been carried out by both experimental and clinical points of view. Among these are works dealing with chemical or biological agents capable of activating tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). TRAIL is a member of the tumor necrosis factor (TNF) superfamily, highly homologous to CD95/Fas, which is expressed by several cell types. TRAIL ligates two types of receptors: death receptor (DRs), triggering apoptosis, and decoy receptors, which negatively modulate this pathway.1, 2 To date, four human receptors specific for TRAIL have been identified: the DRs TRAILR1 (DR4) and TRAILR2 (DR5), and the putative decoy receptors TRAILR3 (DCR1) and TRAILR4 (DCR2).3 Binding of TRAIL, or administration of agonistic antibodies to DR4 or DR5, resulted in receptor oligomerization and initiation of apoptosis via recruitment of membrane-proximal caspases (caspase 8 or caspase 10).4 Furthermore, it has previously been suggested that death receptors can be recruited into specific plasma membrane regions called lipid rafts that could facilitate proteinCprotein interactions and convey apoptotic signals.5, 6 Lipid rafts are Carmustine plasma membrane microdomains varying in size from 50 to 70?nm, enriched in cholesterol and sphingolipids, and having many important roles in cell signal transduction. In fact, proteins located in these microdomains are severely limited in their ability to freely diffuse over the plasma membrane,7 and their concentration and association into lipid rafts can influence their function and signaling.8, 9 It has been hypothesized that cell treatment with TRAIL Carmustine could trigger the redistribution of receptors DR4 and/or DR5 into lipid rafts potentiating apoptosis.10, 11, 12 Promising preclinical results using either recombinant soluble TRAIL or agonistic death receptor antibodies prompted phase I/II clinical trials exploring the safety and efficacy of these treatments. However, although these clinical studies have demonstrated a good toxicity profile, the major caveat was the highly variable response of cancer cells to apoptosis induction. In the present study, we investigated in several human cell types, including non-transformed cells, as well as in CD19+ lymphocytes from patients with B-chronic lymphocytic leukemia, the possible implication of lipid raft microdomains in determining cell susceptibility to TRAIL-induced apoptosis. We show that the constitutive localization of TRAIL receptor DR4 into lipid rafts could represent a critical variable causing anticancer activity of TRAIL. The mechanism for this sensitivity seems to be based on the association, within lipid microdomains, of DR4, but not DR5, with a specific ganglioside, that is, the monosialoganglioside monoganglioside 3 (GM3). This molecular interaction appears.