Cilostazol suppresses superoxide production and expression of adhesion molecules in human endothelial cells via mediation of cAMP-dependent protein kinase-mediated maxi-K channel activation.
This study shows whether increased intracellular cAMP level by cilostazol is directly coupled to its maxi-K channel activation in human endothelial cells. Cilostazol (1 microM) increased the K+ currents in the human endothelial cells by activating maxi-K channels, which was abolished by iberiotoxin (100 nM), a maxi-K channel blocker. On incubation of human coronary artery endothelial cells with tumor necrosis factor-alpha (TNF-alpha) (50 ng/ml), monocyte adhesion significantly increased with increased superoxide generation and expression of vascular cell adhesion molecule-1 (VCAM-1) and monocyte chemoattractant protein-1 (MCP-1) accompanied by increased degradation of inhibitory kappaBalpha in cytoplasm and activation of nuclear factor-kappaB p65 in nucleus. All these variables were significantly suppressed by cilostazol (10 microM), which was antagonized by iberiotoxin (1 microM) and (9R,10S,12S)-2,3,9,10,11,12-hexahydro-10-hydroxy-9-methyl-1-oxo-9,12-epoxy-1H-diindolo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-l] [1,6]benzodiazocine-10-carboxylic acid hexyl ester (KT 5720) (300 nM, cAMP-dependent protein kinase inhibitor), but not by (9S,10R,12R)-2,3,9,10,11,12-hexahydro-10-methoxy-2,9-dimethyl-1-oxo-9,12-epoxy-1H-diindo-lo[1,2,3-fg:3',2',1'-kl]pyrrolo[3,4-I][1,6]benzodiazocine-10-carboxylic acid methyl ester (KT 5823) (300 nM, cGMP-dependent protein kinase inhibitor). In the human endothelial cells transfected with siRNA-targeting maxi-K channels, cilostazol did not suppress the superoxide generation, VCAM-1 and MCP-1 expressions, and monocyte adhesion as contrasted with the wild-type cells. These findings were similarly evident with (3S)-(+)-(5-chloro-2-methoxyphenyl)-1,3-dihydro-3-fluoro-6-(trifluoromethyl)-2H-indole-2-one (BMS-204352), a maxi-K channel opener, and forskolin and dibutyryl cAMP. In conclusion, increased cAMP level by cilostazol is directly coupled to its maxi-K channel opening action via protein kinase activation in human endothelial cells, thereby suppressing TNF-alpha-stimulated superoxide production and expression of adhesion molecules.
Department of Pharmacology, College of Medicine, Pusan National University, 10-Ami-Dong 1-Ga, Seo-Gu, Busan 602-739, Korea.
So Youn
SY
Park
Jeong Hyun
JH
Lee
Chi Dae
CD
Kim
Won Suk
WS
Lee
Won Sun
WS
Park
Jin
J
Han
Yong-Geun
YG
Kwak
Ki Young
KY
Kim
Ki Whan
KW
Hong
D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D018932:Chemokine CCL2 / Q000378:metabolism; D000077407:Cilostazol; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects / Q000235:genetics; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics; D013481:Superoxides / Q000378:metabolism*; D013777:Tetrazoles / Q000494:pharmacology*; D014162:Transfection; D019010:Vascular Cell Adhesion Molecule-1 / Q000096:biosynthesis*
D018932:Chemokine CCL2; D051036:Large-Conductance Calcium-Activated Potassium Channels; D034741:RNA, Small Interfering; D013777:Tetrazoles; D019010:Vascular Cell Adhesion Molecule-1; D013481:Superoxides; D017868:Cyclic AMP-Dependent Protein Kinases; D000077407:Cilostazol