Phospholipase A2: New lessons from endothelial cells

The investigation of intracellular phospholipase A2 (PLA2) enzymes in endothelial cells (ECs) seems interesting because it may contribute to unveil the mechanisms of biological processes such as angiogenesis, adhesion and transmigration of inflammatory cells, atherogenesis, blood brain barrier and tumor progression. To date, limited information is available regarding the function and regulation of three well characterized phospholipases, Ca2+-dependent cytosolic PLA2 (cPLA2), Ca2+-independent PLA2 (iPLA2) and secretory PLA2 (sPLA2) along the intracellular signaling pathways in quiescent and proliferating ECs. PLA2s could be potentially involved in signaling cascades by which ECs promote the highly organized multicellular complexes consisting of either an endothelium, brain pericytes and astrocytes, or cellular constituents of the tumor microvasculature. This review will summarize recent findings on the presence and possible role attributed to PLA2s in a variety of EC lines grown alone, as well as in isolated cancer cell lines, or in co-cultures in which signal transduction and cross-talk mechanisms between tumor cells and ECs, largely undefined, begin to be unravelled.