Apoptosis mediated by phosphatidylcholine-specific phospholipase C is associated with cAMP, p53 level, and cell-cycle distribution in vascular endothelial cells.

In previous studies, the authors found that phosphatidylcholine-specific phospholipase C (PC-PLC) was implicated in apoptosis induced by deprivation of survival factors in vascular endothelial cells (VECs) (Miao et al. Endothelium, 5, 231-239, 1997). In order to understand which elements are involved in the apoptotic signal transduction mediated by PC-PLC, the authors examined cyclic adenosine monophosphate (cAMP) level, p53 expression, and the changes of cell cycle in VECs when PC-PLC activity was suppressed by D609 (tricyclodecan-9-yl-xanthogenate), a specific inhibitor of this enzyme. The results showed that cAMP level was reduced (p <.01), p53 expression was suppressed, and cell-cycle distribution was changed when apoptosis of VECs was inhibited by D609. The data indicate that cAMP and p53 are involved in this pathway, and that PC-PLC might regulate apoptosis by affecting the cell-cycle distribution of VECs.