title: HO-1 Induced by Cilostazol Protects Against TNF-α-associated Cytotoxicity via a PPAR-γ-dependent Pathway in Human Endothelial Cells.
abstract: A large body of evidence has indicated that induction of endogenous antioxidative proteins seems to be a reasonable strategy for delaying the progression of cell injury. In our previous study, cilostazol was found to increase the expression of the antioxidant enzyme heme oxygenase-1 (HO-1) in synovial cells. Thus, the present study was undertaken to examine whether cilostazol is able to counteract tumor necrosis factor-α (TNF-α)-induced cell death in endothelial cells via the induction of HO-1 expression. We exposed human umbilical vein endothelial cells (HUVECs) to TNF-α (50 ng/ml), with or without cilostazol (10 µM). Pretreatment with cilostazol markedly reduced TNF-α-induced viability loss in the HUVECs, which was reversed by zinc protoporphyrine IX (ZnPP), an inhibitor of HO-1. Moreover, cilostazol increased HO-1 protein and mRNA expression. Cilostazol-induced HO-1 induction was markedly attenuated not only by ZnPP but also by copper-protoporphyrin IX (CuPP). In an assay measuring peroxisome proliferator-activated receptor-γ (PPAR-γ) transcription activity, cilostazol directly increased PPAR-γ transcriptional activity which was completely abolished by HO-1 inhibitor. Furthermore, increased PPAR-γ activity by cilostazol and rosiglitazone was completely abolished in cells transfected with HO-1 siRNA. Taken together, these results indicate that cilostazol up-regulates HO-1 and protects cells against TNF-α-induced endothelial cytotoxicity via a PPAR-γ-dependent pathway.
authors.affiliation: Department of Pharmacology, School of Medicine, and MRC for Ischemic Tissue Regeneration and Medical Research Institute, Pusan National University, Yangsan 626-770, Korea.
authors.forename: So Youn
authors.initials: SY
authors.lastname: Park
authors.forename: Jin Ung
authors.initials: JU
authors.lastname: Bae
authors.forename: Ki Whan
authors.initials: KW
authors.lastname: Hong
authors.forename: Chi Dae
authors.initials: CD
authors.lastname: Kim