Cilostazol Prevents Tumor Necrosis Factor-α-Induced Cell Death by Suppression of Phosphatase and Tensin Homolog Deleted from Chromosome 10 Phosphorylation and Activation of Akt/Cyclic AMP Response Element-Binding Protein Phosphorylation

Abstract

This study examines the signaling mechanism by which cilostazol prevents neuronal cell death. Cilostazol (ϳ0.1-100 M) prevented tumor necrosis factor-␣ (TNF-␣)-induced decrease in viability of SK-N-SH and HCN-1A cells, which was antagonized by 1 M iberiotoxin, a maxi-K channel blocker. TNF-␣ did not suppress the viability of the U87-MG cell, a phosphatase and tensin homolog deleted from chromosome 10 (PTEN)-null glioblastoma cell, but it did decrease viability of U87-MG cells transfected with expression vectors for the sense PTEN, and this decrease was also prevented by cilostazol. Cilostazol as well as 1,3-dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-benzimidazol-2-one (NS-1619) and (3S)-(ϩ)-(5-chloro-2-methoxyphenyl)-1,3-dihydro-3-fluoro-6-(trifluoromethyl)-2H-indole-2-one (BMS 204352), maxi-K channel openers, prevented increased DNA fragmentation evoked by TNF-␣, which were antagonizable by iberiotoxin. TNF-␣-induced increased PTEN phosphorylation and decreased Akt/ cyclic AMP response element-binding protein (CREB) phosphorylation were significantly prevented by cilostazol, those of which were antagonized by both iberiotoxin and paxilline, maxi-K channel blockers. The same results were evident in U87-MG cells transfected with expression vectors for sense PTEN. Cilostazol increases the K ϩ current in SK-N-SH cells by activating maxi-K channels without affecting the ATP-sensitive K ϩ channel. Thus, our results for the first time provide evidence that cilostazol prevents TNF-␣-induced cell death by suppression of PTEN phosphorylation and activation of Akt/CREB phosphorylation via mediation of the maxi-K channel opening.Recent research has shown that the phosphatase and tensin homolog deleted from chromosome 10 (PTEN) is implicated in the regulation of several cellular functions, including cell viability from apoptosis (Li et al., 1998;Stambolic et al., 1998;Cantley and Neel, 1999). PTEN is capable of dephosphorylating both phospho-tyrosine and phospho-serine/threonine-containing substrates (Myers et al., 1997) and also of dephosphorylating the phosphatidylinositol-3,4,5-triphosphate [PI(3,4,5)P 3 ], a direct product of phosphatidylinositol 3-kinase (PI3-K) activity, thereby converting the PI(3,4,5)P 3 to phosphatidylinositol 3,4-diphosphate [PI(3,4)P 2 ], an inactive state (Maehama and Dixon, 1998;Stambolic et al., 1998). Huang et al. (2001) have demonstrated that transient transfection of PTEN into the PTEN-null cells results in decrease in Bcl-2 mRNA and protein, and loss of PTEN leads to up-regulation of the Bcl-2 gene. Overexpression of PI3-K and its downstream effector Akt (serine/threonine kinase) have been documented to mediate growth factor-induced neuronal survival (Crowder and Freeman, 1998) and to up-regulate Bcl-2 promoter activity associated with increased Bcl-2

Cilostazol Reduces Atherosclerosis by Inhibition of Superoxide and Tumor Necrosis Factor-α Formation in Low-Density Lipoprotein Receptor-Null Mice Fed High Cholesterol

“…When the expression of tissue cAMP in the proximal ascending aorta including aortic sinus was determined by immunohistochemistry, a significant elevation of cAMP expression was identified in the mice fed a 0.2% w/w cilostazol-supplemented high fat diet (data not shown). Most recently, cilostazol was found to increase the K ϩ currents in SK-N-SH cells (human brain neuroblastoma, Hong et al, 2003) and human coronary artery endothelial cells (K. W. Hong, unpublished data) by activating the maxi-K channels. It has been suggested that activation of cAMP-dependent protein kinase A by cAMP-elevating agents, such as forskolin and dibutyryl cAMP, inhibits TNF-␣-induced NF-B-dependent reporter gene expression and reduces endogenous NF-B-dependent adhesion molecule and chemokine expression (Ollivier et al, 1996;Aizawa et al, 2003).…”

Inhibitory Effects of Cilostazol on Proliferation of Vascular Smooth Muscle Cells (VSMCs) Through Suppression of the ERK1/2 Pathway

“…In addition, cilostazol inhibits high glucose-mediated endothelial-neutrophil adhesion by decreasing adhesion molecule expression via NO production. It also prevents remnant lipoprotein particleinduced monocyte adhesion to endothelial cells by suppressing the expression of adhesion molecules and monocyte chemoattractant protein-1 via a lectin-like receptor for oxidized low-density lipoprotein receptor activation 21) . Furthermore, cilostazol suppresses superoxide production and the expression of adhesion molecules in human endothelial cells via the mediation of cAMP-dependent protein kinase-mediated Maxi-K channel activation 22,23) .…”

HO-1 Induced by Cilostazol Protects Against TNF-α-associated Cytotoxicity via a PPAR-γ-dependent Pathway in Human Endothelial Cells

“…Kim et al [11] reported a protective effect of cilostazol against lipopolysaccharide (LPS)-induced apoptosis in human umbilical vein endothelial cells (HUVECs). Hong et al [12] demonstrated the ability of cilostazol to prevent tumor necrosis factor-α (TNF-α)-induced cell death in human neuroblastoma cells. An in vivo study in an animal model of middle cerebral artery occlusion and reperfusion also provided evidence of the protective effect of cilostazol against cerebral infarct through anti-apoptotic actions.…”