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ABSTRACT: Advanced melanoma is the most virulent form of cancer and has a poor prognosis. In a previous study, myriocin, an inhibitor of serine palmitoyltransferase, was found to suppress melanoma cell proliferation by cell cycle arrest at the G 2/M phase through decreased sphingolipid levels and increased p53 and p21 (waf1/cip1) expression. ( 1) In the present study, myriocin (1 mg/kg, every other day for 3 weeks) was administered intradermally or intraperitoneally to melanoma mice. Tumor formation was significantly inhibited by intradermal and intraperitoneal administration of myriocin. The expression of Cdc25C, Cdc2 and cyclin B1 was decreased in tumor tissues from myriocin-treated mice, while the expression of p53 and p21 (waf1/cip1) was increased compared with that of the controls. The levels of sphingolipids in serum, liver and tumor tissue from myriocin-treated mice were decreased compared with those of controls. The decreased levels of sphingolipids in serum and liver of melanoma mice treated with myriocin suggests that myriocin may be accessible to tumor tissues of advanced melanoma. Taken together, the suppression of sphingolipid synthesis by myriocin inhibits the expression of Cdc25C or activates the expression of p53 and p21 (waf1/cip1) . This is followed by Cdc2 and cyclin B1 inhibition which results in the suppression of tumor growth.
Cancer biology & therapy 01/2012; 13(2):92-100. · 2.64 Impact Factor
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Kyu-Dong Yoo,
Eun-Seok Park, Yong Lim,
Shin-Il Kang,
Su-Hyang Yoo,
Ha-Hee Won,
Young-Hee Kim,
Ick-Dong Yoo,
Hwan-Soo Yoo,
Jin Tae Hong,
Yeo-Pyo Yun
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ABSTRACT: Abnormal proliferation of vascular smooth muscle cells (VSMCs) plays an essential role in the pathogenesis of vascular diseases, such as atherosclerosis, hypertension, and restenosis. Clitocybin A, a novel isoindolinone, isolated from the culture broth of mushroom Clitocybe aurantiaca has been reported to possess free radical scavenging activity. However, the antiproliferative effects of clitocybin A on VSMCs are unknown. In the present study, we investigated the effect of clitocybin A on platelet-derived growth factor (PDGF)-BB-induced proliferation of VSMCs and examined the molecular basis of the underlying mechanism. Clitocybin A inhibited DNA synthesis and cell proliferation. In accordance with these findings, clitocybin A blocked the PDGF-BB-inducible progression through G0/G1 to S phase of the cell cycle in synchronized cells and decreased the expression of cyclin-dependent kinase (CDK) 2, CDK4, cyclin D1, cyclin E, and proliferative cell nuclear antigen. In addition, clitocybin A inhibited the PDGF-BB-induced phosphorylation of phosphatidylinositol 3 kinase (PI3K) / Akt kinase. However, clitocybin A did not change the expression levels of extracellular signal-related kinase (ERK) 1/2, phospholipase C-γ1, and PDGF-Rβ phosphorylation. These results indicate that clitocybin A may inhibit VSMCs proliferation through G1 phase arrest by regulating the PI3K/Akt pathway.
Journal of Pharmacological Sciences 01/2012; 118(2):171-7. · 2.08 Impact Factor
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Kyu-Dong Yoo,
Eun-Seok Park, Yong Lim,
Shin-Il Kang,
Su-Hyang Yoo,
Ha-Hee Won,
Hee-Pom Lee,
Young-Hee Kim,
Ick-Dong Yoo,
Hwan-Soo Yoo,
Jin-Tae Hong,
Yeo-Pyo Yun
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ABSTRACT: The increased proliferation of vascular smooth muscle cells (VSMCs) in the arterial wall is a critical pathogenic factor for vascular diseases such as atherosclerosis and restenosis after angioplasty. Clitocybin B was reported to have either a potent free radical scavenging effect or effects that were isolated from the culture broth of mushroom Clitocybe aurantiaca. The present study was designed to investigate the effects of clitocybin B on VSMC proliferation and its possible molecular mechanism. Clitocybin B significantly inhibited the proliferation and the DNA synthesis of PDGF-BB-stimulated VSMCs in a concentration-dependent manner. In agreement with these findings, clitocybin B suppressed the PDGF-BB-induced progression through G0/G1 to S phase of cell cycle. Clitocybin B also down-regulated the expressions of cell cycle-related proteins, including cyclin-dependent kinase (CDK)2, cyclin E, CDK4, cyclin D1, and proliferative cell nuclear antigen in PDGF-BB-stimulated VSMCs. Clitocybin B significantly inhibited the phosphorylation of Akt, extracellular signal-regulated kinase 1/2, and phospholipase C-γ1, in the PDGF-BB signaling pathway. Clitocybin B suppressed the PDGF-Rβ activation in PDGF-BB signaling cascade. These results suggested that the inhibitory effect of clitocybin B on the proliferation of VSMCs may be associated with suppressing PDGF-Rβ phosphorylation. Thus, clitocybin B may be an effective antiproliferative agent for the prevention of atherosclerosis and restenosis.
Vascular Pharmacology 12/2011; 56(1-2):91-7. · 1.99 Impact Factor
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Yong Lim,
Munkhtsetseg Tudev,
Eun-Seok Park,
Won-Shik Kim,
Il-Ho Lim,
Mi-Yea Lee,
Heesoon Lee,
Jae-Kyung Jung,
Jin-Tae Hong,
Hwan-Soo Yoo,
Myung-Koo Lee,
Myoung-Yun Pyo,
Yeo-Pyo Yun
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ABSTRACT: The proliferation and migration of vascular smooth muscle cells (VSMCs) play important roles in the formation and progression of intimal thickening in early-phase atherosclerosis and in restenosis after vascular injury. Tumor necrosis factor-α (TNF-α) is released from macrophages in atherosclerotic lesions and from neointimal vascular smooth muscle cells after balloon-injury. Obovatol, a major biphenolic component isolated from the Magnolia obovata leaf, is known to have anti-inflammatory and antitumor activities. The goal of this study was to examine the cardioprotective effects of the obovatol derivative OD 78 on the TNF-α-induced proliferation and migration of rat aortic smooth muscle cells (RASMCs). The antiproliferative effects of OD 78 on RASMCs were examined by cell counting and [(3)H]-thymidine incorporation assays. Treatment of cells with 1-4 μM OD 78 inhibited the proliferation and DNA synthesis of TNF-α-stimulated RASMCs in a concentration-dependent manner, without cytotoxicity. Treatment with OD 78 inhibited TNF-α-mediated p38 phosphorylation, but did not change the activation of extracellular signal-regulated kinase or c-Jun N-terminal kinase. Furthermore, treatment with OD 78 decreased TNF-α-induced levels of cyclin E, cyclin D1, CDK2, proliferating cell nuclear antigen, and phosphorylated retinoblastoma protein, but not the CDK4 expression level. Also, OD 78 inhibits the migration of TNF-α-induced RASMC in transwells. OD 78 treatment strongly decreased matrix metalloproteinase-9 (MMP-9) expression in a dose-dependent manner, but the MMP-2 expression was unchanged. These results show that OD 78 may be developed as a potential antiproliferative agent for the treatment of angioplasty restenosis and atherosclerosis.
Archives of Pharmacal Research 07/2011; 34(7):1191-9. · 1.59 Impact Factor
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ABSTRACT: Ceramide 1-phosphate (C1P) is a novel bioactive sphingolipid formed by ceramide kinase (CERK)-catalyzed phosphorylation of ceramide. It has been implicated in the regulation of such vital pathophysiological functions as phagocytosis and inflammation, but there have been no reports ascribing a biological function to CERK in vascular disorders. Here the potential role of CERK/C1P in neointimal formation was investigated using rat aortic vascular smooth muscle cells (VSMCs) in primary culture and a rat carotid injury model. Exogenous C8-C1P stimulated cell proliferation, DNA synthesis, and cell cycle progression of rat aortic VSMCs in primary culture. In addition, wild-type CERK-transfected rat aortic VSMCs induced a marked increase in rat aortic VSMC proliferation and [(3)H]-thymidine incorporation when compared to empty vector transfectant. C8-C1P markedly activated extracellular signal-regulated kinase 1 and 2 (ERK1/2) within 5min, and the activation could be prevented by U0126, a MEK inhibitor. Also, K1, a CERK inhibitor, decreased the ERK1/2 phosphorylation and cell proliferation on platelet-derived growth factor (PDGF)-stimulated rat aortic VSMCs. CERK expression and C1P levels were found to be potently increased during neointimal formation using a rat carotid injury model. However, ceramide levels decreased during the neointimal formation process. These findings suggest that C1P can induce neointimal formation via cell proliferation through the regulation of the ERK1/2 protein in rat aortic VSMCs and that CERK/C1P may regulate VSMC proliferation as an important pathogenic marker in the development of cardiovascular disorders.
Experimental Cell Research 05/2011; 317(14):2041-51. · 3.58 Impact Factor
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ABSTRACT: Thrombosis occurs in the coronary arteries via the activation of platelets, and leads to acute myocardial infarction and sudden death. Obovatol, a major biphenolic component of Magnolia Obovata leaves, displays anti-inflammatory and acyl Co-A cholesterol acyltrasferase inhibitory effects. The purpose of this study was to determine the effects of obovatol on thrombus formation in vivo and platelet activation in vitro and ex vivo.
We investigated the antiplatelet and antithrombotic activities of obovatol in rat carotid arterial thrombosis in vivo along with platelet aggregation in vitro and ex vivo. Its possible cellular mechanism of antiplatelet activity was investigated by testing PLC-γ2 activation, arachidonic acid cascade, calcium mobilization and granule secretion.
Oral administration of obovatol prevented carotid thrombosis, but also significantly inhibited collagen-induced platelet aggregation. Obovatol did not change coagulation times, such as activated partial thromboplastin time and prothrombin time, indicating that the antithrombotic effect of obovatol might be due to antiplatelet activity rather than anticoagulation activity. Obovatol inhibited in vitro collagen- and arachidonic acid-induced rabbit platelet aggregation in a concentration-dependent manner (1-10 µM), with IC(50) values of 2.4 ± 0.8 and 4.8 ± 0.9 µM, respectively. Obovatol blocked collagen-mediated phospholipase C-γ2 phosphorylation, cytoplasmic calcium mobilization, arachidonic acid liberation and serotonin secretion.
Obovatol has a potent antithrombotic effect, which may be due to antiplatelet activity. The antiplatelet activity of obovatol is mediated by inhibition of PLC-γ2 phosphorylation. Thus, obovatol may be a potential candidate to treat cardiovascular disease.
Journal of atherosclerosis and thrombosis 04/2011; 18(8):659-69. · 2.69 Impact Factor
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ABSTRACT: The abnormal proliferation of vascular smooth muscle cells (VSMCs) in arterial wall is an important pathogenic factor for vascular disorders such as atherosclerosis and restenosis after angioplasty. The present study was designed to investigate the inhibitory effects of docetaxel on VSMC proliferation, as well as the molecular mechanism of this inhibition. Docetaxel at 10, 20 and 40 µM significantly inhibited both the proliferation and the DNA synthesis of fetal bovine serum (FBS)- and platelet-derived growth factor (PDGF)-BB-stimulated VSMCs in a concentration-dependent manner. In accordance with these findings, docetaxel blocked the FBS- and PDGF-BB-induced progression of synchronized cells through the G0/G1 phase of the cell cycle. Docetaxel also decreased the expressions of cell cycle-related proteins, including cyclin-dependent kinase (CDK) 2, cyclin E, CDK4, cyclin D1, retinoblastoma protein, and proliferative cell nuclear antigen in PDGF-BB-stimulated VSMCs. Docetaxel significantly inhibited the phosphorylation of extracellular signal-regulated kinase 1/2, Akt, and phospholipase C-γ1, downstream molecule in the PDGF-BB signaling pathway. Docetaxel suppressed the phosphorylation of PDGF receptor (PDGF-R) β, the upstream molecule in PDGF-BB signaling cascade, suggesting that the inhibitory effect of docetaxel on the proliferation of VSMCs may occur by blocking PDGF-Rβ phosphorylation. Thus, docetaxel may be a potential antiproliferative agent for the treatment of atherosclerosis and angioplasty restenosis.[Supplementary Figures: available only at http://dx.doi.org/10.1254/jphs.10276FP].
Journal of Pharmacological Sciences 01/2011; 116(2):204-13. · 2.08 Impact Factor
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ABSTRACT: We have previously reported that fenofibrate displayed a potent antithrombotic effect by the inhibition of platelet aggregation. The present study was designed to investigate the effects of fenofibrate on the neointimal hyperplasia and its possible molecular mechanism. Neointimal hyperplasia was measured in balloon-inflated-induced vascular injury model of male Sprague-Dawley rats and cell proliferation was measured in primary cultured rat aortic vascular smooth muscle cells (VSMCs). Fenofibrate-treated group showed a significant reduction in neointimal formation (0.07±0.04mm(2)) from the control (0.13±0.04mm(2)). Fenofibrate significantly inhibited platelet-derived growth factor (PDGF)-BB-induced cell counting and [(3)H]-thymidine incorporation into DNA. Fenofibrate suppressed the PDGF-BB-inducible progression through G(0)/G(1) to S phase of cell cycle. Moreover, fenofibrate inhibited not only phosphorylation of retinoblastoma (Rb) protein and expression of cyclin D/E, CDK 2/4 and proliferating cell nuclear antigen (PCNA) proteins but also mitogen-activated protein kinase (MAPK) signaling pathways such as ERK 1/2, p38 and JNK phosphorylation. In conclusion, the present study demonstrates that fenofibrate significantly inhibits neointimal formation via G(0)/G(1) arrest of PDGF-BB-induced cell proliferation in association with the inhibition of MAPK, which resulted in the downregulation of expressions of cyclin D/E, CDK 2/4 and PCNA proteins, suggesting that fenofibrate may be useful for individuals with a high risk of thrombotic or cardiovascular diseases.
European journal of pharmacology 10/2010; 650(1):342-9. · 2.59 Impact Factor
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ABSTRACT: Obovatol is isolated from Magnolia obovata leaves and this active component has various pharmacological properties such as anti-oxidant, anti-platelet, anti-fungal and anti-inflammatory activities. In the present study, we investigated the inhibitory effects of obovatol on in vitro vascular smooth muscle cell (VSMC) proliferation and in vivo neointimal formation in a rat carotid artery injury model.
Obovatol (1-5 microM) exerted concentration-dependent inhibition on platelet-derived growth factor (PDGF)-BB-induced rat VSMC proliferation, without exhibiting any cellular toxicity or apoptosis, as determined by cell count, [3H]thymidine incorporation and Annexin-V-binding analyses. Treatment with obovatol blocked the cell cycle in G1 phase by down-regulating the expression of cyclins and CDKs, and selectively up-regulating the expression of p21Cip1, a well-known CDK inhibitor. Effects of perivascular delivery of obovatol were assessed 14 days after injury. The angiographic mean luminal diameters of the obovatol-treated groups (100 microg and 1 mg: 0.78+/-0.06 and 0.77+/-0.07AU, respectively) were significantly larger than that of the control group (0.58+/-0.07AU). The obovatol-treated groups (100 microg and 1mg: 0.14+/-0.04 and 0.09+/-0.03 mm2, respectively) showed significant reduction in neointimal formation versus the control group (0.17+/-0.02 mm2). Immunohistochemical staining demonstrated strong expression of p21Cip1 in the neointima of the obovatol-treated groups.
These data suggest that obovatol inhibits VSMC proliferation by perturbing cell cycle progression, possibly due to activation of p21Cip1 pathway. These results also show that obovatol may have potential as an anti-proliferative agent for the treatment of restenosis and atherosclerosis.
Atherosclerosis 11/2009; 210(2):372-80. · 3.79 Impact Factor
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Tack-Joong Kim,
Hyeong-Jun Han, Yong Lim,
Min-Cheol Song,
Jihee Kim,
Jin-Tae Hong,
Hwan-Soo Yoo,
Myoung-Yun Pyo,
Bang-Yeon Hwang,
Myoung-Koo Lee,
Yeo-Pyo Yun
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ABSTRACT: Cudrania tricuspidata has been proposed to possess anti-inflammatory, antioxidant, hepatoprotective, and antitumor activities. Although cudraflavone B, isolated from the root bark of C. tricuspidata, has a variety of pharmacological effects, its effects on rat aortic smooth muscle cells (RASMCs) are unclear. In the present study, cudraflavone B was found to inhibit cell proliferation and DNA synthesis in cultured RASMCs. Pretreatment with cudraflavone B (0.1-4 microM) suppressed platelet-derived growth factor-BB (PDGF-BB)-stimulated cell number in a concentration-dependent manner. The inhibition percentages were 19.7%, 36.4%, 52.3%, and 99.1% at concentrations of 0.1, 1, 2, and 4 microM, respectively. Moreover, cudraflavone B inhibited [H]-thymidine incorporation into DNA in RASMCs in response to 25 ng/mL PDGF-BB. PDGF-BB-stimulated DNA synthesis was significantly reduced by 15.9%, 31.7%, 43.1%, and 78.2% at concentrations of 0.1, 1, 2, and 4 muM, respectively. Thus, cudraflavone B blocked the PDGF-BB-inducible progression through G0/G1 to S phase of the cell cycle in synchronized cells. Furthermore, PDGF-BB-induced phosphorylation of retinoblastoma protein (pRb), the hyperphosphorylation of which is a hallmark of the G1-S transition in the cell cycle, was significantly inhibited by cudraflavone B. Because pRb phosphorylation is regulated by cyclin-dependent kinases (CDKs), we investigated the expression of CDK2, CDK4, cyclin E, and cyclin D1 and the CDK inhibitors p21 and p27. Treatment with cudraflavone B downregulated the cyclins and CDKs and upregulated the expression of p21 and p27, a CDK inhibitor. These findings suggest that cudraflavone B inhibits RASMC proliferation via the induction of p21 and p27 expression and subsequent cell cycle arrest with reduction of pRb phosphorylation at the G1-S phase.
Journal of cardiovascular pharmacology 04/2009; 53(4):341-8. · 2.83 Impact Factor
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Jung-Jin Lee,
Yong-Ri Jin,
Ji-Yeon Yu,
Tudev Munkhtsetseg,
Eun-Seok Park, Yong Lim,
Tack-Joong Kim,
Myoung-Yun Pyo,
Jin Tae Hong,
Hwan-Soo Yoo,
Youngsoo Kim,
Yeo-Pyo Yun
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ABSTRACT: Fenofibrate, a lipid-lowering drug, inhibits hydroxyl-methylglutaryl coenzyme A (HMG-CoA)-reductase activity, thus reducing cholesterol synthesis and increasing the clearance of circulating LDL-cholesterol via the high affinity receptor system. In addition, fenofibrate has beneficial effects such as the inhibition of tissue factor expression, antithrombotic effect and anti-inflammatory effect. The aim of this study was to investigate the effects of fenofibrate on thrombus formation in vivo and platelet activation in vitro and ex vivo. The carotid arteries of male Sprague-Dawley rats were subjected to chemical injury by FeCl(3), and then blood flow was measured with a blood flowmeter. Fenofibrate (200 and 400mg/kg/day for 1 week) delayed the time to occlusion by 61.3% (p<0.05, n=10) and 90.7% (p<0.01, n=10), respectively. Fenofibrate also significantly inhibited ex vivo platelet aggregations induced by collagen (7.5microg/ml) (p<0.01, n=11) and ADP (10microM) (p<0.01, n=11), respectively, but did not affect coagulation times following activated partial thromboplastin and prothrombin activation, indicating the antithrombotic effect was mediated by its inhibition on platelet activation rather than coagulation system. This antiplatelet activity was revealed to be mediated by the suppression of thromboxane A(2) receptor, cytosolic calcium mobilization, and cyclooxygenase (COX)-1 activity. Taken together, we demonstrate that fenofibrate can significantly inhibit artery thrombus formation in vivo, which may be due to antiplatelet activity via the inhibition of thromboxane A(2) receptor, cytosolic calcium mobilization and COX-1 activity, and the beneficial effect of fenofibrate on cardiovascular system may be also due to its modulation of platelet activation.
Atherosclerosis 03/2009; 206(2):375-82. · 3.79 Impact Factor
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ABSTRACT: Diet is one of the most important factors that influence the risks for cardiovascular diseases. Genistein, an isoflavone found in soy, may benefit the cardiovascular system. Here, we investigated the effect of genistein on platelet-derived growth factor (PDGF)-BB-induced proliferation of primary cultured rat aortic smooth muscle cells (RASMCs). Genistein significantly inhibited 25 ng/ml PDGF-BB-induced RASMC proliferation and [3H]-thymidine incorporation into DNA at 10, 20, and 40 microM. In accordance with these findings, genistein blocked the PDGF-BB-inducible progression through G0/G1 to S phase of the cell cycle in synchronized cells. Western blot analysis showed that genistein not only inhibited phosphorylation of retinoblastoma protein (pRb) and expression of cyclin E, cyclin-dependent kinase (CDK) 2, and proliferating cell nuclear antigen (PCNA) protein, but also inhibited downregulation of cyclin-dependent kinase inhibitor (CKI) p27kip1. However, genistein did not affect p21cip1, CDK4, and cyclin D1 expression or early signal transduction through PDGF beta-receptor, extracellular signal-regulated kinases 1/2 (ERK1/2), Akt, and phospholipase C (PLC) gamma1 phosphorylation. These results suggest that genistein inhibits PDGF-BB-induced RASMC proliferation via G0/G1 arrest in association with induction of p27kip1, which may contribute to the beneficial effects of genistein on the cardiovascular system.
Journal of Pharmacological Sciences 06/2008; 107(1):90-8. · 2.08 Impact Factor
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ABSTRACT: Diet can be one of the most important factors that influence risks for cardiovascular diseases. Hesperetin, a flavonoid present in grapefruits and oranges, is one candidate that may benefit the cardiovascular system. In this study, we have investigated the effect of hesperetin on the platelet-derived growth factor (PDGF)-BB-induced proliferation of primary cultured rat aortic vascular smooth muscle cells (VSMCs). Hesperetin significantly inhibited 50 ng/ml PDGF-BB-induced rat aortic VSMCs proliferation and [(3)H]-thymidine incorporation into DNA at concentrations of 5, 25, 50, and 100 microM. In accordance with these findings, hesperetin revealed blocking of the PDGF-BB-inducible progression through G(0)/G(1) to S phase of the cell cycle in synchronized cells. Western blot showed that hesperetin inhibited not only phosphorylation of retinoblastoma protein (pRb) and expressions of cyclin A, cyclin D, cyclin E, cyclin-dependent kinase 2 (CDK2) as well as proliferating cell nuclear antigen (PCNA) protein, but also downregulation of cyclin-dependent kinase inhibitor (CKI) p27(kip1), while did not affect CKI p21(cip1), p16(INK4), p53, and CDK4 expressions as well as early signaling transductions such as PDGF beta-receptor, extracellular signal-regulated kinase (ERK) 1/2, Akt, p38, and JNK phosphorylation. These results suggest that hesperetin inhibits PDGF-BB-induced rat aortic VSMCs proliferation via G(0)/G(1) arrest in association with modulation of the expression or activation of cell-cycle regulatory proteins, which may contribute to the beneficial effect of grapefruits and oranges on cardiovascular system.
Journal of Cellular Biochemistry 06/2008; 104(1):1-14. · 2.87 Impact Factor
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ABSTRACT: We have previously reported that green tea catechins displayed a potent antithrombotic effect by inhibition of platelet aggregation. In the present study, the antiplatelet and antithrombotic activities of epigallocatechin gallate (EGCG), the major catechin derived from green tea, were extensively investigated. EGCG inhibited arterial thrombus formation and U46619-, collagen-, and arachidonic acid (AA)-induced washed rabbit platelet aggregation in a concentration-dependent manner, with IC50 values of 61 +/- 3, 85 +/- 4, and 99 +/- 4 microM, respectively. In line with the inhibition of collagen-induced platelet aggregation, EGCG revealed blocking of the collagen-mediated phospholipase (PL) Cgamma2 and protein tyrosine phosphorylation, and it caused concentration-dependent decreases of cytosolic calcium mobilization, AA liberation, and serotonin secretion. In addition, the platelet aggregation, intracellular Ca2+ mobilization, and protein tyrosine phosphorylation induced by thapsigargin, a Ca2(+)-ATPase pump inhibitor, were completely blocked by EGCG. Contrary to the inhibition of AA-induced platelet aggregation, EGCG failed to inhibit cyclooxygenase and thromboxane (TX) A2 synthase activities, but it concentration-dependently elevated AA-mediated PGD2 formation. In contrast, epigallocatechin (EGC), a structural analogue of EGCG lacking a galloyl group in the 3' position, slightly inhibited collagen-stimulated cytosolic calcium mobilization, but failed to affect other signal transductions as did EGCG in activated platelets and arterial thrombus formation. These results suggest that antiplatelet activity of EGCG may be attributable to its modulation of multiple cellular targets, such as inhibitions of PLCgamma2, protein tyrosine phosphorylation and AA liberation, and elevation of cellular PGD2 levels, as well as maintaining Ca2(+)-ATPase activity, which may underlie its beneficial effect on the atherothrombotic diseases.
Journal of Cardiovascular Pharmacology 02/2008; 51(1):45-54. · 2.29 Impact Factor
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ABSTRACT: NQ12, an antithrombotic agent, has been reported to display a potent antiplatelet activity. This study was undertaken to reveal the effect of NQ12 on rabbit platelet aggregation and signal transduction involved in the arachidonic acid (AA) cascade. NQ12 concentration-dependently suppressed collagen-, AA-, and U46619-induced rabbit platelet aggregation, with IC(50) values of 0.71 +/- 0.2, 0.82 +/- 0.3, and 0.45 +/- 0.1 microM, respectively. In addition, the concentration-response curve of U46619 was shifted to the right after NQ12 treatment, indicating an antagonism on thromboxane (TX) A(2) receptors. The collagen-stimulated AA liberation was inhibited by NQ12 in the same pattern as its inhibition of platelet aggregation. Further study revealed that NQ12 potently suppressed AA-mediated TXA(2) formation, but had no effect on the PGD(2) production, indicating an inhibitory effect on TXA(2) synthase, which was supported by a TXA(2) synthase activity assay indicating that NQ12 concentration-dependently inhibited TXA(2) formation converted from PGH(2). On the other hand, the AA-stimulated 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE) formation was also suppressed by NQ12. Taken together, these results suggest that NQ12 has a potential to inhibit TXA(2) synthase activity and TXA(2) receptors, and it can modulate AA liberation as well as 12-HETE formation in platelets. This may be a convincing mechanism for the antithrombotic action of NQ12.
Journal of Pharmacological Sciences 11/2007; 105(2):193-200. · 2.08 Impact Factor
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Tack-Joong Kim, Yong Lim,
Dong-Woon Kim,
Jin-Sook Kwon,
Ju-Hee Son,
Yong-Ri Jin,
Dong Ju Son,
Jae-Chul Jung,
Mitchell A Avery,
Jin Tae Hong,
Yeo-Pyo Yun
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ABSTRACT: Epothilone D (Epo-D) is a paclitaxel-like microtubule-stabilizing agent that was isolated from the myxobacterium Sorangium cellulosum. Although Epo-D can inhibit proliferation in multiple tumor cell lines, the effect of Epo-D on neointimal hyperplasia after angioplasty has not been reported. The aim of the present study was to investigate the effects of Epo-D on neointimal hyperplasia using an in vivo rat carotid artery injury model. We demonstrated that local Epo-D treatment significantly reduced neointimal hyperplasia after in vivo rat carotid artery injury, and Epo-D potently inhibited DNA synthesis, cell cycle progression and cell proliferation after FBS- and PDGF-BB-stimulation; PDGF-BB has been identified as the most potent growth factor for stimulating the proliferation of activated rat aortic smooth muscle cells (RASMCs). To clarify the specific effects of Epo-D on cell cycle machinery, we examined its effects on cyclin-dependent kinase (CDK)2, CDK4, cyclin E, p27, and retinoblastoma (Rb) proteins as cell cycle-related proteins in cellular lysates from PDGF-BB-stimulated RASMCs. Epo-D treatment significantly decreased the level of CDK2 protein, but did not change the levels of CDK4 and cyclin E proteins. Furthermore, Epo-D inhibited the phosphorylation of Rb, a key regulator of the G1 to S phase transition in the cell cycle. These findings suggest that Epo-D may regulate the cell cycle G1-checkpoint proteins as its major molecular mechanism for inhibiting neointimal hyperplasia after in vivo rat carotid artery injury.
Vascular Pharmacology 11/2007; 47(4):229-37. · 1.99 Impact Factor
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ABSTRACT: Diet can be one of the most important factors that influence risks for atherothrombotic diseases. Hesperetin included in grapefruits and oranges is one candidate that may benefit the cardiovascular system. Here, we investigated antiplatelet activity of hesperetin in vitro. In addition, possible antiplatelet mechanism was also investigated. Hesperetin concentration-dependently inhibited washed rabbit platelet aggregation induced by collagen and arachidonic acid, with IC50 of 20.5+/-3.5 and 69.2+/-5.1 microM, respectively, while has little effect on thrombin- or U46619-, a thromboxane (TX) A2 mimic, mediated platelet aggregation, suggesting that hesperetin may selectively inhibit collagen- and arachidonic acid-mediated signal transduction. In accordance with these findings, hesperetin revealed blocking of the collagen-mediated phospholipase (PL) C-gamma2 phosphorylation, and caused concentration-dependent decreases of cytosolic calcium mobilization, arachidonic acid liberation and serotonin secretion. In addition, hesperetin inhibited arachidonic acid-mediated platelet aggregation by interfering with cyclooxygenase-1 activity as established by the measurement of arachidonic acid-mediated TXA2 and prostaglandin D2 formations as well as cyclooxygenase-1 and TXA2 synthase activity assays. Taken together, the present results provide a cellular mechanism for the antiplatelet activity of hesperetin through inhibition of PLC-gamma2 phosphorylation and cyclooxygenase-1 activity, which may contribute to the beneficial effects of grapefruits and oranges on cardiovascular system.
Atherosclerosis 10/2007; 194(1):144-52. · 3.79 Impact Factor
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Yong Lim,
Tack-Joong Kim,
Yong-Ri Jin,
Dong-Woon Kim,
Jin-Sook Kwon,
Ju-Hee Son,
Jae-Chul Jung,
Mitchell A Avery,
Dong Ju Son,
Jin Tae Hong,
Yeo-Pyo Yun
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ABSTRACT: The abnormal proliferation of vascular smooth muscle cells (VSMCs) in arterial walls is an important pathogenetic factor of vascular disorders such as atherosclerosis and restenosis after angioplasty. Epothilone B, a novel potential antitumor compound, has a potent effect on preventing postangioplasty restenosis. Therefore, we established an in vivo rat carotid injury model and examined the potential effects of epothilone B on cardiovascular disease. We found that epothilone B potently prevented neointimal formation and in vivo VSMCs proliferation. In addition, we also showed that epothilone B significantly inhibited 5% fetal bovine serum (FBS)- and 50 ng/ml platelet-derived growth factor (PDGF)-BB-induced proliferation and cell cycle progression in rat aortic VSMCs. Furthermore, FBS and PDGF-BB induced the activations of extracellular signal-regulated kinases 1 and 2, Akt, phospholipase C gamma 1, and PDGF-receptor beta chain tyrosine kinase were not changed by epothilone B. However, epothilone B treatment caused a significant decrease in the level of cyclin-dependent protein kinase (CDK) 2, whereas it caused no change in the levels of cyclin E and down-regulated the phosphorylation of retinoblastoma, which plays a critical role in cell cycle regulation. Furthermore, levels of p27, an inhibitor of cyclin E/CDK2 complex, were significantly increased in VSMCs treated with epothilone B, indicating that this might be a major molecular mechanism for the inhibitory effects of epothilone B on the proliferation and cell cycle of VSMCs. These findings suggest that epothilone B can inhibit neointimal formation via the cell cycle arrest by the regulation of the cell cycle-related proteins in VSMCs.
Journal of Pharmacology and Experimental Therapeutics 06/2007; 321(2):648-55. · 3.83 Impact Factor
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ABSTRACT: Oleanolic acid (3beta-hydroxy-olea-12-en-28-oic), a pentacyclic triterpenoid, exists widely in the plant kingdom and has a wide variety of pharmacological effects such as antitumor, antifungal, insecticidal, hepatoprotective and anti-HIV activities. This paper reports that oleanolic acid induces the aggregation of rabbit platelets, a mechanism was also investigated. Oleanolic acid at concentrations of 25, 50, 100 and 200 microM induced the aggregation of washed rabbit platelets in a concentration-dependent manner. Pretreating the platelets with U73122, a phospholipase C (PLC) inhibitor, blocked the oleanolic acid induced-aggregation, whereas acetylsalicylic acid (ASA), a cyclooxygenase (COX) inhibitor, had no effect. In addition, the effect of oleanolic acid on serotonin secretion, which is a marker for dense granule secretion, was determined. Oleanolic acid induced serotonin secretion in a similar concentration-dependent manner as observed with platelet aggregation. Pretreating the platelets with U73122 blocked the oleanolic acid-induced serotonin secretion and cytosolic calcium mobilization. Overall, these results suggest that oleanolic acid can induce platelet aggregation, which may be mediated by the stimulation of PLC-mediated cytosolic calcium mobilization.
Archives of Pharmacal Research 03/2007; 30(2):210-4. · 1.59 Impact Factor
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Dong-Ju Son, Yong Lim,
Young-Hyun Park,
Sung-Keun Chang,
Yeo-Pyo Yun,
Jin-Tae Hong,
Gary R Takeoka,
Kwang-Geun Lee,
Sung-Eun Lee,
Mi-Ran Kim,
Jeong-Han Kim,
Byeoung-Soo Park
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ABSTRACT: The antiplatelet and antiproliferative activities of extract of Tabebuia impetiginosa inner bark (taheebo) were investigated using washed rabbit platelets and cultured rat aortic vascular smooth muscle cells (VSMCs) in vitro. n-Hexane, chloroform and ethyl acetate fractions showed marked and selective inhibition of platelet aggregation induced by collagen and arachidonic acid (AA) in a dose-dependent manner. These fractions, especially the chloroform fraction, also significantly suppressed AA liberation induced by collagen in [(3)H]AA-labeled rabbit platelets. The fractions, especially the chloroform fraction, potently inhibited cell proliferation and DNA synthesis induced by platelet derived growth factor (PDGF)-BB, and inhibited the levels of phosphorylated extracellular signal regulated kinase (ERK1/2) mitogen activated protein kinase (MAPK) stimulated by PDGF-BB, in the same concentration range that inhibits VSMC proliferation and DNA synthesis.
Journal of Ethnopharmacology 12/2006; 108(1):148-51. · 3.01 Impact Factor
