Protection from apoptotic cell death by cilostazol, phosphodiesterase type III inhibitor, via cAMP-dependent protein kinase activation

This study aimed to elucidate whether the effect of cilostazol to suppress apoptotic cell death is directly coupled to cAMP-dependent protein kinase activation in human umbilical vein endothelial cells (HUVECs). After exposure of HUVECs to LPS (1 μg ml−1) for 18 h, the endothelial cells irregularly aggregated with loss of cobblestone appearance, which was reversed by cilostazol (1–100 μM), as well as by cilostamide (cilostazol analog), and cilostazol metabolites (OPC-13015 and OPC-31213), respectively. LPS-stimulated production of reactive oxygen species (ROS) was significantly reduced by cilostazol (0.1–10 μM). In line with these, LPS (1 μg ml−1)- and TNF-α (200 ng ml−1)-induced DNA fragmentation, assessed by agarose gel electrophoresis, was significantly reduced by treatment with cilostazol (10 μM) as well as by dibutyryl cAMP (100 μM). This effect was reversed by cAMP-dependent protein kinase inhibitor, Rp-cAMPs (200 μM). Further, LPS (1 μg ml−1)-induced decrease in Bcl-2 and increase in Bax protein expression were fully reversed by cilostazol (10 μM) and dibutyryl cAMP (100 μM), all of which were antagonized by Rp-cAMPs (200 μM). Taken together, cilostazol effectively protected HUVECs from LPS- and TNF-α-induced cell death associated with oligonucleosomal DNA fragmentation via activation of cAMP-dependent protein kinase.