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Ki Young Kim

Publications and source records attributed to Ki Young Kim.

At least 19 recordsLinked to original sources
PubMed2026

Comparative Multiomics Analysis of Cerebral Organoid-Derived Exosomes during Organoid Maturation.

Cerebral organoids derived from human pluripotent stem cells recapitulate key features of early brain development and provide a physiologically relevant model for neurogenesis. Exosomes secreted by these organoids carry bioactive cargo and offer a noninvasive means to monitor maturation and intercellular communication. We performed comprehensive multiomics profiling of exosomes collected from cerebral organoids at defined developmental stages to evaluate their utility as biomarkers of neuronal differentiation. Metabolomic analysis revealed a progressive decline in amino acids, including glutamic acid, consistent with increased metabolic demand during neurogenesis. Lipidomic and neurosteroid profiling showed dynamic increases in phosphatidylethanolamine and pregnenolone, reflecting synaptic membrane formation and signaling. Transcriptomic and proteomic analyses identified stage-specific neurodevelopmental signatures, with key markers mirroring those of parent organoids. Collectively, cerebral organoid-derived exosomes faithfully reflect organoid maturation and provide a robust platform for tracking in vitro brain development.

Humans↗
PubMed2006

Differential anti-proliferative actions of peroxisome proliferator-activated receptor-gamma agonists in MCF-7 breast cancer cells.

Peroxisome proliferator-activated receptor-gamma (PPARgamma) activation has been a new approach to cancer therapy. In the present study, we investigated the effects of two structurally different PPARgamma agonists, rosiglitazone and KR-62980 on MCF-7 breast cancer cells. Both agonists inhibited the cell proliferation and colony formation via apoptosis. PTEN expression was increased with decreased Akt phosphorylation by the agonists, whereas agonists actions were abolished in PTEN knockdown cells, indicating the critical role of PTEN in the anti-proliferative effects of PPARgamma activation. Rosiglitazone induced the MCF-7 cell differentiation but KR-62980 did not alter the differentiation pattern with little effects on the lipid accumulation and the expression of lipogenesis markers. These results suggest that PPARgamma activation may result in the inhibition of cell proliferation and/or induction of cell differentiation depending on the type of PPARgamma agonists, and that KR-62980 may be useful in breast cancer therapy by inducing apoptosis.

Apoptosis↗
PubMed2006

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 microgml(-1)) for 18 h, the endothelial cells irregularly aggregated with loss of cobblestone appearance, which was reversed by cilostazol (1-100 microM), 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 microM). In line with these, LPS (1 microgml(-1))- and TNF-alpha (200 ngml(-1))-induced DNA fragmentation, assessed by agarose gel electrophoresis, was significantly reduced by treatment with cilostazol (10 microM) as well as by dibutyryl cAMP (100 microM). This effect was reversed by cAMP-dependent protein kinase inhibitor, Rp-cAMPs (200 microM). Further, LPS (1 microgml(-1))-induced decrease in Bcl-2 and increase in Bax protein expression were fully reversed by cilostazol (10 microM) and dibutyryl cAMP (100 microM), all of which were antagonized by Rp-cAMPs (200 microM). Taken together, cilostazol effectively protected HUVECs from LPS- and TNF-alpha-induced cell death associated with oligonucleosomal DNA fragmentation via activation of cAMP-dependent protein kinase.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed2006

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.

Cell Adhesion↗
PubMed2006

Antiangiogenic effect of rosiglitazone is mediated via peroxisome proliferator-activated receptor gamma-activated maxi-K channel opening in human umbilical vein endothelial cells.

Recent evidence shows that peroxisome proliferator-activated receptor gamma (PPARgamma) ligands induce the antiangiogenic effect in endothelial cells and tumors. In the present study, we elucidated the involvement of maxi-K channel activation in the antiangiogenic effect of rosiglitazone, a well known PPARgamma ligand in human umbilical vein endothelial cells. We found that the antiangiogenic effects of rosiglitazone were reversed by either bisphenol A diaglycidyl ether, a PPARgamma antagonist, or iberiotoxin, a maxi-K channel blocker. Knockdown of maxi-K channel expression also reversed the antiangiogenic effects. Iberiotoxin reversed the rosiglitazone-induced hyperpolarization while having no effect on the endogenous PPARgamma activation, suggesting that rosiglitazone activates maxi-K channel via PPARgamma. In the rosiglitazone-induced antiangiogenic process, endothelial nitric-oxide synthase-Ser1179 phosphorylation and NO production were significantly elevated, and treatment with the NOS inhibitor N(G)-monomethyl-L-arginine acetate abolished the antiangiogenic and apoptotic effects of rosiglitazone, indicating NO as a key mediator of the rosiglitazone actions. In conclusion, rosiglitazone significantly inhibited VEGF165-induced angiogenesis by a proapoptotic mechanism via PPARgamma-mediated NO production, followed by maxi-K channel opening.

Benzimidazoles↗
PubMed2006

Neuroprotection by cilostazol, a phosphodiesterase type 3 inhibitor, against apoptotic white matter changes in rat after chronic cerebral hypoperfusion.

In the present study, we elucidated effect of cilostazol to prevent the occurrence of vacuolation and rarefaction of the white matter in association with apoptosis induced by bilateral occlusion of common carotid arteries in the male Wistar rats. Rats orally received vehicle (DMSO) or 60 mg kg(-1) day(-1) (orally) cilostazol for 3, 7, 14 or 30 days. In the vehicle group, increased vacuolation and rarefactions in the white matter were accompanied by extensive activation of both microglial and astroglial cells with suppression of oligodendrocytes in association with increased TNF-alpha production, caspase-3 immunoreactivity and TUNEL-positive cells in the white matter including optic tract. Post-treatment with cilostazol (60 mg kg(-1) day(-1)) strongly suppressed not only elevated activation of astroglia and microglia but also diminished oligodendrocytes following chronic cerebral hypoperfusion. In conclusion, cilostazol (60 mg kg(-1) day(-1), orally) significantly reduced the apoptotic cell death in association with decreased TNF-alpha production and caspase-3-positive cells in the white matter of rat brains subjected to bilateral occlusion of common carotid arteries, consequently ameliorating vacuoles and rarefaction changes in the white matter.

Administration, Oral↗
PubMed2004

Anti-apoptotic action of (2S,3S,4R)-N"-cyano-N-(6-amino-3,4-dihydro-3-hydroxy-2-methyl-2-dimethoxymethyl-2H-benzopyran-4-yl)-N'-benzylguanidine (KR-31378) by suppression of the phosphatase and tensin homolog deleted from chromosome 10 phosphorylation and increased phosphorylation of casein kinase2/Akt/ cyclic AMP response element binding protein via maxi-K channel opening in neuronal cells.

This study shows the signaling pathway by which (2S,3S,4R)-N"-cyano-N-(6-amino-3,4-dihydro-3-hydroxy-2-methyl-2-dimethoxymethyl-2H-benzopyran-4-yl)-N'-benzylguanidine (KR-31378) prevents tumor necrosis factor (TNF)-alpha-induced neuronal cell death. KR-31378 restored TNF-alpha-induced decreased cell viability of SK-N-SH. U87-MG cells (PTEN-null glioblastoma cell line) transfected with expression vectors for sense PTEN (phosphatase and tensin homolog deleted from chromosome 10) showed significantly decreased cell viability, which was restored by KR-31378. TNF-alpha-induced increased PTEN phosphorylation and decreased phosphorylation of Akt/cyclic AMP response element-binding protein (CREB) in SK-N-SH cells were concentration-dependently reversed by KR-31378, those of which were antagonized by iberiotoxin, a maxi-K channel blocker. TNF-alpha and apigenin, a casein kinase2 (CK2) inhibitor, showed decreased CK2 phosphorylation and increased PTEN phosphorylation, which were reversed by KR-31378. KR-31378 increased K(+) currents by activating the maxi-K channels in SK-N-SH cells, with suppression of TNF-alpha-induced increase in cytosolic Ca(2+) and elevation of suppressed mitochondrial membrane potential, all of which were antagonized by iberiotoxin. It is suggested that increase in cell viability by KR-31378 is ascribed to the maxi-K channel opening-coupled upregulation of CK2/Akt/CREB phosphorylation and downregulation of PTEN phosphorylation in association with increased Bcl-2 and decreased Bax levels.

Apoptosis↗
PubMed2004

Remnant lipoprotein particles induce apoptosis in endothelial cells by NAD(P)H oxidase-mediated production of superoxide and cytokines via lectin-like oxidized low-density lipoprotein receptor-1 activation: prevention by cilostazol.

BACKGROUND: Remnant lipoprotein particles (RLPs), products of lipolytic degradation of triglyceride-rich lipoprotein derived from VLDL, exert atherogenesis. In this study, we observed how RLPs induced cytotoxicity in human umbilical vein endothelial cells (HUVECs) and cilostazol prevented cell death. METHODS AND RESULTS: RLPs were isolated from the plasma of hyperlipidemic patients by use of an immunoaffinity gel mixture of anti-apolipoprotein A-1 and anti-apolipoprotein B-100 monoclonal antibodies. RLPs (50 microg/mL) significantly increased superoxide formation in HUVECs associated with elevated gp91phox mRNA and protein expression and Rac1 translocation, accompanied by increased production of tumor necrosis factor (TNF)-alpha and interleukin-1beta, DNA fragmentation, and cell death. Cilostazol (1 to 100 micromol/L) significantly suppressed not only NAD(P)H oxidase-dependent superoxide production but also TNF-alpha and interleukin-1beta release and restored viability. RLPs activated a lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), which was not inhibited by cilostazol. Treatment of HUVECs with monoclonal antibody for LOX-1 attenuated RLP-mediated production of superoxide, TNF-alpha, and interleukin-1beta and DNA fragmentation. CONCLUSIONS: RLPs stimulated NAD(P)H oxidase-dependent superoxide formation and induction of cytokines in HUVECs via activation of LOX-1, consequently leading to reduction in cell viability with DNA fragmentation, and cilostazol exerts a cell-protective effect by suppressing these variables.

Adult↗
PubMed2003

Cilostazol prevents focal cerebral ischemic injury by enhancing casein kinase 2 phosphorylation and suppression of phosphatase and tensin homolog deleted from chromosome 10 phosphorylation in rats.

This study shows the in vivo neuroprotective effect of cilostazol against cerebral ischemic injury evoked by subjecting rats to 2-h occlusion of middle cerebral artery (MCAO) followed by 24-h reperfusion. We observed the signaling pathway by which cilostazol suppressed MCAO-induced increased phosphorylation of phosphatase and tensin homolog deleted from chromosome 10 (PTEN) and apoptosis via increased phosphorylation of casein kinase 2 (CK2). When rats received 30 mg/kg cilostazol orally two times at 5 min and 4 h after the completion of ischemia, the infarct area was significantly reduced in the cortex and striatum with improvement of neurological deterioration. Increased DNA fragmentation in the penumbral zone was significantly reduced by cilostazol. Cilostazol significantly elevated phosphorylation levels of CK2, Akt, and cyclic AMP response element-binding protein (CREB) in association with increased Bcl-2 in the ischemic area, whereas the elevated PTEN phosphorylation was significantly reduced, all of which were antagonized by iberiotoxin, a maxi-K channel blocker, administered intracisternally 30 min before ischemia. In conclusion, cilostazol ameliorates the neuronal damage by suppression of apoptotic cell death via the maxi-K channel opening-coupled up-regulation of CK2 phosphorylation and down-regulation of PTEN phosphorylation with resultant increase in the Akt and CREB phosphorylation and increased Bcl-2 protein.

Animals↗
PubMed2003

Cilostazol enhances casein kinase 2 phosphorylation and suppresses tumor necrosis factor-alpha-induced increased phosphatase and tensin homolog deleted from chromosome 10 phosphorylation and apoptotic cell death in SK-N-SH cells.

This study shows the signaling pathway by which cilostazol suppresses tumor necrosis factor-alpha (TNF-alpha)-induced the phosphatase and tensin homolog deleted from chromosome 10 (PTEN) phosphorylation and apoptosis via casein kinase 2 (CK2) phosphorylation in the SK-N-SH cells (neuroblastoma cells). Cilostazol (10 microM) fully restored cell proliferation with suppression of DNA fragmentation induced by TNF-alpha and emodin, a CK2 inhibitor, which were antagonized by iberiotoxin, a maxi-K channel blocker. Under application of TNF-alpha or emodin, increased PTEN phosphorylation and decreased phosphorylation of CK2/Akt/cyclic AMP response element-binding protein (CREB), and CK2 activity were significantly reversed by cilostazol (approximately 1-100 microM), all of which were antagonized by iberiotoxin. 1,3-dihydro-1-[2-hydroxy-5-(trifluoromethyl)phenyl]-5-(trifluoromethyl)-2H-benzimidazol-2-one (NS-1619) and (3S)-(+)-(5-chloro-2-methoxyphenyl-1,3-dihydro-3-fluoro-6-(trifluoromethyl)-2H-indol-2-one (BMS 204352) maxi-K channel openers significantly elevated CK2 activities that were reversible by iberiotoxin. SK-N-SH cells treated with antisense CK2 oligodeoxynucleotide showed a prominent DNA fragmentation with little responsiveness to TNF-alpha in the phosphorylation of PTEN, indicative of the essential role of p-CK2/CK2 in cell proliferation, and the decreased cell viability of these cells was not restored by cilostazol. It is suggested that the action of cilostazol promoting cell survival is ascribed to the maxi-K channel opening-coupled up-regulation of CK2 phosphorylation and down-regulation of PTEN phosphorylation with resultant increased phosphorylation of Akt and CREB.

Apoptosis↗
PubMed2003

Cilostazol prevents tumor necrosis factor-alpha-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.

This study examines the signaling mechanism by which cilostazol prevents neuronal cell death. Cilostazol ( approximately 0.1-100 microM) prevented tumor necrosis factor-alpha (TNF-alpha)-induced decrease in viability of SK-N-SH and HCN-1A cells, which was antagonized by 1 microM iberiotoxin, a maxi-K channel blocker. TNF-alpha 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)(+)-(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-alpha, which were antagonizable by iberiotoxin. TNF-alpha-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+ current in SK-N-SH cells by activating maxi-K channels without affecting the ATP-sensitive K+ channel. Thus, our results for the first time provide evidence that cilostazol prevents TNF-alpha-induced cell death by suppression of PTEN phosphorylation and activation of Akt/CREB phosphorylation via mediation of the maxi-K channel opening.

Cell Death↗
PubMed2003

KR-31372 inhibits KDR/Flk-1 tyrosine phosphorylation via K+(ATP) channel opening in its antiangiogenic effect.

The aim of this study was to identify the signaling pathway of the antiangiogenesis by (2R,3R,4S)-N-cyano-N-(6-nitro-3,4-dihydro-hydroxy-2-methyl-2-dimethoxymethyl 2H-1-benzopyran-4yl)-N'-benzylguanidine (KR-31372). KR-31372 inhibited the in vitro basal tube formation using Matrigel-coated plate and in vivo neovascularizations in mice induced by Matrigel containing vascular endothelial growth factor (VEGF(165), 5 ng/ml). VEGF(165) markedly increased cell proliferation using 5-bromo-2'-deoxyuridine incorporation and chemotactic migration using transwell chamber in human umbilical vein endothelial cells, those of which were significantly suppressed by pretreatment with KR-31372 and levcromakalim concentration dependently. The suppression of all these variables were strongly antagonized by glibenclamide, ATP-sensitive K(+) channel blocker. KR-31372 (10(-6)-10(-4) M) and levcromakalim (10(-5) M) concentration-dependently suppressed the VEGF(165)-induced increases in KDR/Flk-1 tyrosine phosphorylation as well as the extracellular signal-related kinase 1/2 (ERK1/2), p38 MAK and p125(FAK) tyrosine phosphorylation. These variables were significantly antagonized by glibenclamide. In conclusion, KR-31372 significantly inhibited the KDR/Flk-1 tyrosine phosphorylation-linked ERK1/2, p38 MAPK and p125(FAK) tyrosine phosphorylation via mediation of K(+)(ATP) channel opening, thereby resulting in antiangiogenesis.

Adenosine Triphosphate↗
PubMed2003

Antiangiogenic effect of KR-31372 by apoptosis via mediation of mitochondrial KATP channel opening and the phosphatase and tensin homolog deleted from chromosome 10 phosphorylation.

Antiangiogenic action of (2R,3R,4S)-N"-cyano-N-(6-nitro-3,4-dihydro-hydroxy-2-methyl-2-dimethoxymethyl-2H-1-benzopyran-4yl)-N'-benzyl guanidine (KR-31372) was examined with its proapoptotic action in human umbilical vein endothelial cells (HUVECs) compared with diazoxide. KR-31372 as well as diazoxide significantly suppressed the neovascularization in mice induced by the Matrigel-containing recombinant human vascular endothelial growth factor (VEGF)165 in vivo and the basal tube formation of HUVECs in vitro with suppression of proliferation of HUVECs stimulated by VEGF165. KR-31372 and diazoxide enhanced DNA fragmentation associated with increase in phosphatase and tensin homolog deleted from chromosome 10 (PTEN) and decrease in serine/threonine kinase phosphorylation, which were accompanied by augmented Bax and cytochrome c release, and suppressed Bcl-2 in HUVECs. In the U87-MG cells, when transfected with expression vectors for sense PTEN, KR-31372 enhanced DNA fragmentation, but not in naive U87-MG cells. The suppression by KR-31372 and diazoxide of these variables was significantly antagonized by 5-hydroxydecanoic acid, a mitochondrial KATP channel blocker. Taken together, KR-31372 strongly inhibited angiogenesis in HUVECs by proapoptotic mechanism via mediation of 5-hydroxydecanoic acid-inhibitable mitochondrial KATP channel opening and PTEN phosphorylation.

Angiogenesis Inhibitors↗
PubMed2002

Impairment of autoregulatory vasodilation by NAD(P)H oxidase-dependent superoxide generation during acute stage of subarachnoid hemorrhage in rat pial artery.

This study assessed the mechanism(s) by which the autoregulatory vasodilation of rat pial artery in response to acute hypotension during the acute phase of subarachnoid hemorrhage (SAH) was markedly blunted. Increased superoxide production from the cerebral vessels in response to NAD(P)H at 24 hours after SAH + NG-nitro-l-arginine methyl ester (l-NAME) (10 mg/kg) was inhibited by intracisternal administration of a tyrosine kinase inhibitor genistein (10 micromol/L) and Rac inhibitor Clostridium difficile toxin B (1 ng/mL) and a flavoenzyme inhibitor diphenyleneiodonium (10 micromol/L). The expression of gp91phox was enhanced by SAH + l-NAME from 12 to 24 hours, which was inhibited by genistein and toxin B, but not the p22phox. Increased membrane translocation of Rac after SAH + l-NAME was attenuated by both genistein and toxin B, whereas increased tyrosine kinase activity was blocked by genistein, but not by toxin B. The blunted autoregulatory vasodilation to acute hypotension was effectively recovered by genistein and C. difficile toxin B as well as by diphenyleneiodonium. In conclusion, SAH during acute stage causes an increase in NAD(P)H oxidase-dependent superoxide formation in cerebral vessels, which is due to activation of tyrosine phosphorylation-dependent increased expression of gp91phox mRNA and translocation of Rac protein, thereby resulting in a significant reduction of autoregulatory vasodilation.

Animals↗
PubMed2002

Seabed classification from acoustic profiling data using the similarity index.

We introduce the similarity index (SI) for the classification of the sea floor from acoustic profiling data. The essential part of our approach is the singular value decomposition of the data to extract a signal coherent trace-to-trace using the Karhunen-Loeve transform. SI is defined as the percentage of the energy of the coherent part contained in the bottom return signals. Important aspects of SI are that it is easily computed and that it represents the textural roughness of the sea floor as a function of grain size, hardness, and a degree of sediment sorting. In a real data example, we classified a section of the sea floor off Cheju Island south of the Korean Peninsula and compared the result with the sedimentology defined from direct sediment sampling and side scan sonar records. The comparison shows that SI can efficiently discriminate the bottom properties by delineating sediment-type boundaries and transition zones in more detail. Therefore, we propose that SI is an effective parameter for geoacoustic modeling.

Acoustics↗
PubMed2002

Prevention of lipopolysaccharide-induced apoptosis by (2S,3S,4R)-N"-cyano-N-(6-amino-3,4-dihydro-3-hydroxy-2-methyl-2-dimethoxymethyl-2H-benzopyran-4-yl)-N'-benzylguanidine, a benzopyran analog, in endothelial cells.

This study describes the antiapoptotic action of (2S,3S,4R)-N"-cyano-N-(6-amino-3,4-dihydro-3-hydroxy-2-methyl-2-dimethoxymethyl-2H-benzopyran-4-yl)-N'-benzylguanidine (KR-31378), a novel benzopyran analog, in human umbilical vein endothelial cells (HUVECs) in comparison with its acetylated metabolite, (2S,3S,4R)-N"-cyano-N-(6-acetylamino-3,4-dihydro-3-hydroxy-2-methyl-2-dimethoxymethyl-2H-benzopyran-4-yl)-N'-benzylguanidine (KR-31612), and with alpha-tocopherol. Exposure of HUVECs to lipopolysaccharide (LPS) (1 microg/ml) induced time- and concentration-dependent cytotoxicity and oligonucleosomal DNA fragmentation. KR-31378, KR-31612, and alpha-tocopherol potently suppressed LPS-induced cell death in association with significant reduction in the intracellular reactive oxygen species (ROS) and tumor necrosis factor-alpha (TNF-alpha) that are stimulated by LPS. KR-31378 more effectively protected HUVECs from LPS-induced DNA fragmentation and was more effective in peroxyl radical scavenging than alpha-tocopherol. Incubation with LPS markedly decreased the Bcl-2 level, which was totally reversed by KR-31378 and to a lesser degree by KR-31612 and by alpha-tocopherol. In contrast, the greatly increased Bax protein and cytochrome c release stimulated by LPS were markedly suppressed by KR-31378 and by KR-31612, and to a lesser degree by alpha-tocopherol. Taken together, KR-31378 strongly inhibited cell death in HUVECs in association with antiapoptotic effects, which were accompanied by up-regulation of Bcl-2 protein expression and down-regulation of Bax protein and suppression of cytochrome c release. KR-31378 also showed the properties to scavenge the intracellular ROS and peroxyl radicals, and to reduce the TNF-alpha production induced by LPS.

Apoptosis↗
PubMed2002

Inhibition of lipopolysaccharide-induced apoptosis by cilostazol in human umbilical vein endothelial cells.

This work describes the pharmacological inhibition by cilostazol and its metabolites, OPC-13015 and OPC-13213, of the apoptosis in the human umbilical vein endothelial cells (HUVECs) damaged by lipopolysaccharide (LPS) in comparison with its analog, cilostamide. Cilostazol and OPC-31213 caused a significant suppression of cell death induced by LPS (1 microg/ml) in a concentration-dependent manner but a modest suppression by cilostamide and OPC-13015. These compounds potently inhibited the 5,5-dimethyl-1-pyrroline-1-oxide (DMPO)/(*)OH adduct formation and significantly reduced the increased intracellular reactive oxygen species (ROS) and tumor necrosis factor-alpha (TNF-alpha) production induced by LPS (1 microg/ml). An apoptotic death of HUVECs by 1 microg/ml LPS (DNA ladders on electrophoresis) was strongly suppressed by all these compounds. Incubation with LPS caused a marked decrease in Bcl-2 protein, which was significantly reversed by cilostazol and its analogs. The greatly increased Bax protein expression and cytochrome c release by LPS were, in contrast, suppressed by cilostazol and, to a lesser degree, by others. In conclusion, cilostazol and its analogs exert a strong protection against apoptotic cell death by scavenging hydroxyl radicals and intracellular ROS with reduction in TNF-alpha formation and by increasing Bcl-2 protein expression and decreasing Bax protein and cytochrome c release.

3',5'-Cyclic-AMP Phosphodiesterases↗