The implication of platelet activating factor in cancer growth and metastasis: potent beneficial role of PAF-inhibitors and antioxidants.

Cancer is one of the leading causes of death in Europe and United States. New blood vessel formation penetrating into solid tumors seems to be required for their growth and metastasis. Several protein growth factors can induce endothelial cell proliferation and angiogenesis, through signal transduction cascades that result in the production of several inflammatory mediators and lipid second messengers such as prostaglandins and Platelet Activating Factor (PAF). PAF is a potent mediator of inflammation that is implicated in several inflammatory pathological conditions such as atherosclerosis, cardiovascular and renal diseases, allergy, AIDS, cancer etc. It exerts its biological activities through G-protein-coupled receptors. The presence of PAF in the microenvironment of tumors may be due to its synthesis from circulating and / or cancer cells. Moreover, cancer cells and activated endothelial cells expose PAF-receptor on their membrane surface. PAF binding on its receptor induces several pathways that result in the onset and development of tumor induced angiogenesis and metastasis. PAF-receptor antagonists have exhibited promising results in vitro and in vivo as anti-angiogenic molecules in several cancer cells and tumors. A dietary profile reach in antioxidants and PAF-inhibitors (such as the Mediterranean Diet) may provide beneficial preventive and protective effects against development, growth and metastatic manifestations of cancer cells, through either their inhibition of PAF activity and / or its biosynthesis. The clarification of factors that may down regulate pathologically increased PAF-levels in a tumor microenvironment may also contribute to the planning of a potent nontoxic preventive and therapeutic approach against cancer.