Presence of membrane platelet-activating factor receptors on B cells of chronic B cell leukaemia patients

Inflammation and melanoma growth and metastasis: the role of platelet-activating factor (PAF) and its receptor

An inflammatory tumor microenvironment fosters tumor growth, angiogenesis and metastatic progression. Platelet-activating factor (PAF) is an inflammatory biolipid produced from membrane glycerophospholipids. Through the activity of its G-protein coupled receptor, PAF triggers a variety of pathological reactions including tumor neo-angiogenesis. Several groups have demonstrated that inhibiting PAF-PAF receptor pathway at the level of a ligand or receptor results in an effective inhibition of experimental tumor growth and metastasis. In particular, our group has recently demonstrated that PAF receptor antagonists can effectively inhibit the metastatic potential of human melanoma cells in nude mice. Furthermore, we showed that PAF stimulated the phosphorylation of CREB and ATF-1 in metastatic melanoma cells, which resulted in overexpression of MMP-2 and MT1-MMP. Our data indicate that PAF acts as a promoter of melanoma metastasis in vivo. Since only metastatic melanoma cells overexpress CREB/ATF-1, we propose that these cells are better equipped to respond to PAF within the tumor microenvironment when compared to their non-metastatic counterparts.

Platelet-activating factor changes in phospholipid extracts from the plasma, peripheral blood mononuclear cells and bone marrow mononuclear cells of patients with acute leukemia--a 31P MRS in vitro study

The aim of this investigation was to evaluate the changes in PAF concentrations in the plasma, PBMC and BMMC of patients with acute lymphoblastic leukemia (ALL) and acute myeloblastic leukemia (AML). The plasma was from 23 healthy volunteers (HV) and 44 patients with AL (16 ALL, 28 AML). The PBMC were from 15 HV and 55 patients with AL (18 ALL, 37 AML), and the BMMC from 40 patients with AL (11 ALL, 29 AML). Methanol-chloroform phospholipid extraction from 60 x 10(6) cells (PBMC or BMMC) was performed according to a modified version of Folch's method. (31)P MRS data was obtained on an AMX 300 Bruker spectrometer (7.05 T). The PAF concentration in the plasma of the patients with ALL or AML was lower than that for the healthy volunteers. The PAF concentration in the plasma of the patients with ALL did not differ significantly from that of the patients with AML. In the case of both the PBMC and BMMC, the PAF concentration was significantly diminished in patients with ALL relative to the concentration for those with AML and for the healthy volunteers. No differences were observed in the PAF concentrations for the AML patients and the healthy volunteers.