Cilostazol Inhibits Cytokine-Induced Tetrahydrobiopterin Biosynthesis in Human Umbilical Vein Endothelial Cells

Aims: Cilostazol, a type III phosphodiesterase inhibitor, is utilized for the treatment of intermittent claudication and is considered to have the beneficial effects against the atherogenic process. In the present study, we examined the effects of cilostazol on BH4 biosynthesis in HUVEC treated with...

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Bibliographic Details
Published in:Journal of Atherosclerosis and Thrombosis 2011, Vol.18(4), pp.312-317
Main Authors: Shiraishi, Hiroaki, Ikemoto, Kazuhisa, Tada, Shin, Udagawa, Yasuhiro, Ohtsuki, Masatsugu, Sumi-Ichinose, Chiho, Kondo, Kazunao, Nomura, Takahide
Format: Article
Language:English
Subjects:
Biopterins - analogs & derivatives
Biopterins - antagonists & inhibitors
Biopterins - biosynthesis
Cells, Cultured
Cilostazol
Cyclic AMP
Cytokines - pharmacology
Endothelial Cells - drug effects
Endothelial Cells - metabolism
Fibrinolytic Agents
GTP Cyclohydrolase - analysis
GTP cyclohydrolase I
Humans
HUVEC
Interferon-gamma - pharmacology
Tetrahydrobiopterin
Tetrazoles - pharmacology
Tumor Necrosis Factor-alpha - pharmacology
Umbilical Veins - cytology
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Summary:Aims: Cilostazol, a type III phosphodiesterase inhibitor, is utilized for the treatment of intermittent claudication and is considered to have the beneficial effects against the atherogenic process. In the present study, we examined the effects of cilostazol on BH4 biosynthesis in HUVEC treated with a mixture of the pro-inflammatory cytokines IFN-γ and TNF-α. Methods: Isolated HUVECs were grown to confluence and treated with IFN-γ (300 units/mL) and TNF-α (300 units/mL) for 16 h in order to stimulate BH4 biosynthesis. The BH4 levels were mea-sured by HPLC. The mRNA expression of GTP cyclohydrolase I (GTPCH), the rate-limiting enzyme of BH4 biosynthesis, and GTPCH feedback regulatory protein (GFRP) were quantified by real-time PCR. The GTPCH protein expression was assessed by western blot analysis. Results: Cilostazol significantly reduced the BH4 levels in cytokine-stimulated HUVEC. Cilostazol produced a concomitant increase in the cAMP levels in HUVEC. Cilostazol decreased the GTPCH activity as well as the expression of GTPCH mRNA and protein. 8-bromo-cAMP (8Br-cAMP), a cell-permeable cAMP analogue, did not reproduce the effects of cilostazol. Cilostazol did not affect the cytokine-induced inhibition of GFRP mRNA expression. Conclusions: We conclude that cilostazol inhibited cytokine-stimulated BH4 biosynthesis via a cAMP-independent mechanism in HUVEC. Our data indicate that cilostazol reduced GTPCH activity and did so by suppressing the GTPCH protein levels.
ISSN:1340-3478
1880-3873
DOI:10.5551/jat.6361