Anti-proliferation effect of 5,5-diphenyl-2-thiohydantoin (DPTH) in human vascular endothelial cells

The aim of this study was to examine the anti-proliferation effect of 5,5-diphenyl-2-thiohydantoin (DPTH), an analogue of antiepileptic drug phenytoin (5,5-diphenylhydantoin), on human umbilical vein endothelial cells (HUVEC) and its possible molecular mechanism underlying. Here we demonstrated that DPTH at a range of concentrations (12.5-50 microM) dose- and time-dependently inhibited DNA synthesis and decreased cell number in cultured HUVEC, but not human fibroblasts. DPTH was not cytotoxic at these concentrations. [3H]Thymidine incorporation and flow cytometry analyses demonstrated that treatment of HUVEC with DPTH arrested the cell at the G0/G1 phase of the cell cycle. Western blot analysis revealed that the protein level of p21 increased after DPTH treated. In contrast, the protein levels of p27, p53, cyclins A, D1, D3 and E, cyclin-dependent kinase (CDK)2, and CDK4 in HUVEC were not changed significantly after DPTH treatment. Immunoprecipitation showed that the formations of the CDK2-p21 and CDK4-p21 complex, but not the CDK2-p27 and CDK4-p27 complex, were increased in the DPTH-treated HUVEC. Kinase assay further demonstrated that both CDK2 and CDK4 kinase activities were decreased in the DPTH-treated HUVEC. Pretreatment of HUVEC with a p21 antisense oligonucleotide reversed the DPTH-induced inhibition of [3H]thymidine incorporation into HUVEC. In conclusion, these data suggest that DPTH inhibits HUVEC proliferation by increasing the level of p21 protein, which in turn inhibits CDK2 and CDK4 kinase activities, and finally interrupts the cell cycle. The findings from the present study suggest that DPTH might have the potential to inhibit the occurrence of angiogenesis.     

Inhibition of the effects of thyroxine by 5,5-diphenyl-2-thiohydantoin

5,5-Diphenyl-2-thiohydantoin (DPTH), the sulfur analog of 5,5-diphenylhydantoin (dilantin), inhibited the induction of rat tissue mitochondrial α-glycerophosphate dehydrogenase (GPD) and the stimulation of whole-body metabolic rate by exogenous thyroxine (T₄). It did not affect the tissue uptake, the biliary excretion, or the enterohepatic recirculation of T₄. Like propylthiouracil, it increased the serum protein-bound iodine (and free T₄) when exogenous T₄ was given, and decreased the deiodination in vivo of the hormone. In thyroidectomized rats, DPTH did not inhibit the stimulation of general protein synthesis produced by exogenous T₄, and it had only a little or no effect on the induction of glucose 6-phosphatase, succinic dehydrogenase, and malic enzyme by T₄, or on the induction of tyrosine transaminase by hydrocortisone. The inhibition of GPD induction by DPTH could not be explained by its effects on the general distribution or metabolism of T₄.     

Assessment of diabetogenic drug activity in the rat: 5,5-diphenyl-2-thiohydantoin.

The diabetogenic activity of 5,5-diphenyl-2-thiohydantoin (DPTH) via oral administration was assessed in both normal and streptozotocin diabetic rats. Rats were fed powdered chow diet with and without 0.1% (w/w) DPTH. Food consumption and body weight were recorded every other day; whole blood glucose concentrations were determined at the start of the study and at the midpoint. At sacrifice, liver and pancreas were excised and blood samples were collected. Protein and lipid levels were determined in liver; insulin in pancreas; and glucose, insulin, and lipid in blood. DPTH treatment caused decreased food consumption and body weight gain. The drug dose, calculated from the food consumption data, was 76.5 mg/kg/day for the normal rats and 107 mg/kg/day for the diabetic rats. DPTH increased liver weight and liver lipid content in both normal and diabetic rats, and markedly lowered serum triglyceride concentration in normal rats but not in diabetic rats. Serum fatty acid concentration was not altered by DPTH. DPTH produced a significant elevation of blood glucose concentration of the diabetic rats that was not, however, correlated with altered pancreatic insulin concentration. In vitro, DPTH infusion inhibited insulin secretion by the perfused pancreas.     

Relationship between prostaglandin E2 and vascular endothelial growth factor (VEGF) in angiogenesis in human vascular endothelial cells

To address the role of prostaglandin E2 (PGE2) in tube formation of endothelial cells and the relationships between the action of PGE2 and vascular endothelial growth factor (VEGF), cultured human umbilical vein endothelial cells (HUVECs) were used to evaluate tube formation on Matrigel and the expression of angiogenesis-related genes. PGE2 treatment stimulated the tube-like formation of HUVECs. Whereas VEGF-induced tube formation was significantly suppressed by ETYA, an inhibitor of arachidonic acid metabolism, or SU5614, an inhibitor of VEGF-receptor tyrosine kinase, the stimulatory effect of PGE2 was observed in the presence of ETYA or SU5614. Thus, PGE2 counteracted both ETYA- and SU5614-induced blockage of angiogenesis in the presence of VEGF. VEGF induced cyclooxygenase (COX) -2 mRNA expression in HUVECs and increased the PGE2 concentration in the medium. PGE2 treatment enhanced the expression of VEGF mRNA. These findings suggest that PGE2 directly stimulates angiogenesis, apart from VEGF signaling, and further induces VEGF expression in HUVECs. In addition, the effect of VEGF on angiogenesis may be mediated, in part, by PGE2 secretion.     

Ezetimibe and vascular endothelial function

Hypercholesterolemia is a major risk factor for cardiovascular diseases that has been managed mostly with 3-hydroxy-3-methyl glutaryl coenzyme A reductase inhibitors (statins) that suppress de novo cholesterol synthesis in the liver. Statins also have beneficial pleiotropic effects on the atherosclerotic process that are independent of their ability to lower lipid values. However, the levels of low-density lipoprotein cholesterol (LDL-C) in most hypercholesterolemic patients at high risk for cardiovascular disease do not reach the goals proposed by guidelines even when prescribed with statins. Ezetimibe is a new lipid-lowering agent that blocks the intestinal absorption of dietary and biliary cholesterol and reduces LDL-C levels, especially when combined with statins. However, its effect on cardiovascular events remains unknown. We reviewed the effects of ezetimibe on cardiovascular diseases, in particular, vascular endothelial function, which is initially impaired during the atherogenetic process and is an important predictor of cardiovascular events. The simultaneous inhibition of cholesterol synthesis by statin and of cholesterol absorption by ezetimibe might retard the atherogenetic process. These effects are considered to be mainly mediated by lipid lowering. However, further studies should elucidate the mechanism of the anti-atherosclerotic effects induced by ezetimibe; for instance, whether or not it directly affects atherogenesis independently from its lipid-lowering effects.     

3-Alkyl(aryl)-piperazinoalkyl derivatives of 5,5-diphenylhydantoin

The new obtained N3-alkyl- or arylpiperazinoalkyl substituted derivatives of 5,5-diphenylhydantoin weakly affect the spontaneous motility and the hypermotility induced by amphetamine. They did not show the anticonvulsive activity. Compounds containing the methyl (or phenyl)-piperazine moiety connected by the three-carbon chain with the N3 atom of the hydantoin ring show the strongest activity in the potentiation of the central effect of DOPA.     

人参皂苷单体Rh_2抑制小鼠前胃癌系细胞增殖及其机制

目的探讨人参皂苷Rh2(G-Rh2)对小鼠前胃癌系(MFC)细胞增殖的抑制作用及其机制。方法分别对MFC正常细胞组和G-Rh2(3、10、30mg.L-1)组经MTT法检测MFC细胞活性;倒置显微镜和Hoechst33258荧光染色观察凋亡细胞形态;AnnexinV-FITC双染法分析G-Rh2对细胞凋亡率的影响;分别对MFC正常细胞组、G-Rh2(10mg.L-1)处理不同时间(30min、1、2、4h)组、SP600125(5μmol.L-1)预处理2h+G-Rh2(10mg.L-1)不同时间(30min、1、2、4h)给药组经MTT法检测MFC细胞活性;Westernblot法检测G-Rh2(10mg.L-1)处理不同时间(5、15、30、45min、1、2、4h)组p-JNK(c-JunN-terminalkinase1)激酶和p-c-jun在MFC细胞中的活性,免疫细胞化学染色法检测caspase-3阳性细胞的表达率。结果G-Rh2对无血清MFC细胞有明显细胞毒活性,呈时间和剂量依赖关系;能明显诱导细胞皱缩,核染色质固缩,核碎裂,形成大约为180～200bp或其多聚体组成的寡核苷酸片断,凋亡细胞比率上升。G-Rh2处理后4h内,p-JNK激酶和p-c-jun活性持续升高,此过程可被预处理2h的SP600125(5μmol.L-1)部分抑制。结论人参皂苷G-Rh2可诱导MFC细胞凋亡,其作用机制之一可能是通过激活JNK信号传导途径,并最终增加caspase-3的激活而完成。     

阿魏酸乙酯对过氧化氢损伤人血管内皮细胞的保护作用

目的 :观察阿魏酸乙酯对人血管内皮细胞的保护作用。方法 :实验分对照组、模型组、阿魏酸 4个剂量组、阿魏酸乙酯 4个剂量组。过氧化氢诱导血管内皮细胞损伤 ,用四甲基偶氮唑蓝比色法检测细胞存活数量 ,用比色法测细胞培养液中过氧化物丙二醛含量及乳酸脱氢酶的活性。结果 :阿魏酸乙酯及阿魏酸不同剂量 (2 ,4 ,8,16nmol·L-1)对过氧化氢损伤的人血管内皮细胞具有保护作用 ,可抑制过氧化氢损伤的血管内皮细胞释放乳酸脱氢酶和丙二醛。相同剂量组的阿魏酸乙酯的作用强于阿魏酸。结论 :阿魏酸乙酯具有减轻过氧化氢损伤 ,保护血管内皮细胞的作用 ,并且其作用强于阿魏酸     

血管内皮生长因子受体-3在血管内皮细胞和平滑肌细胞中的表达

目的探讨血管内皮细胞生长因子受体-3（VEGFR-3）在血管内皮细胞和平滑肌细胞中的表达。方法分离人脐带中的脐静脉和脐动脉,冰冻切片后以免疫荧光法检测VEGFR-3的表达。结果VEGFR-3荧光信号表达于脐静脉内皮细胞和平滑肌细胞,以及脐动脉内皮细胞、平滑肌细胞和外周细胞。结论血管内皮细胞和平滑肌细胞均表达VEGFR-3。     

Insulin-like growth factor binding protein-7 (IGFBP7) blocks vascular endothelial cell growth factor (VEGF)-induced angiogenesis in human vascular endothelial cells

Insulin-like growth factor binding protein-7 (IGFBP7) and vascular endothelial growth factor (VEGF) are expressed in vascular endothelial cells in several tumor types. In this study, we examined the effect of IGFBP7 on VEGF-induced tube formation in cultured human umbilical vein endothelial cells (HUVECs) and its potential action in the modulation of VEGF signaling in vascular cells. IGFBP7 treatment suppressed VEGF-induced tube formation, proliferation, and the phosphorylation of mitogen-activated protein kinase kinase (MEK) and extracellular signal-regulated kinase (ERK) 1/2 in HUVECs. IGFBP7 attenuated VEGF-enhanced cyclooxygenase (COX)-2 and VEGF mRNA expression, and prostaglandin E₂ secretion. Knocking down endogenous IGFBP7 enhanced COX-2 and VEGF mRNA expression. A significant increase in IGFBP7-induced caspases was not observed in the presence of VEGF. These findings indicate that IGFBP7 can modulate the stimulatory effect of VEGF on angiogenesis by interfering with VEGF expression as well as VEGF signaling and not by inducing apoptosis.     

Physiology and pathophysiology of proteinase-activated receptors (PARs): role of tryptase/PAR-2 in vascular endothelial barrier function

Proteinase-activated receptor-2 (PAR-2) plays important roles in a variety of pathophysiological functions, including inflammatory responses and nociception. In this minireview, we describe the role of PAR-2 in acute inflammatory responses in lungs associated with iodinated radiographic contrast medium (RCM). Intravenous injection of RCM to rats induces lung injury characterized by vascular hyperpermeability, edema, and respiratory depression. Nafamostat, which is found to be the most potent and specific tryptase inhibitor, prevents RCM-induced lung injury. In cultured endothelial cells of human pulmonary artery and bovine aorta, RCM, when applied in combination with mast cells, disrupts barrier function evaluated by the permeability of Evans blue through a monolayer of cultured cells, which is blocked by nafamostat and mimicked by tryptase and PAR-2-activating peptide. The tryptase-induced barrier dysfunction is blocked completely by a phospholipase C inhibitor and partially inhibited by a IP(3) receptor blocker, protein kinase C inhibitor, or Rho kinase inhibitor. Morphological observations reveal the formation of actin stress fibers and disappearance of the intercellular meshwork structure of vascular endothelial-cadherin after application of RCM or PAR-2 ligands. Therefore, the release of mast cell tryptase and subsequent activation of endothelial PAR-2 are involved in acute lung injury induced by RCM.     

Modulation of P-glycoprotein function by amlodipine derivatives in brain microvessel endothelial cells of rats

AIM: To investigate whether the amlodipine derivatives, CJX1 and CJX2, have a modulative effect on P-glycoprotein (P-gp) function in rat brain microvessel endothelial cells (RBMEC). METHODS: Isolated RBMEC were cultured in DMEM/F12 (1:1) medium. The amount of intracellular rhodamine (Rh123) was determined, using a fluorescence spectrophotometer, to evaluate the function of P-gp. RESULTS: The accumulation of Rh123 in RBMEC was potentiated in a concentration-dependent manner after incubation with CJX1 and CJX2 at 1, 2.5, 5, and 10 micromol/L (P<0.01), but no accumulation of Rh123 was observed in human umbilical vein endothelial cells after incubation with CJX1 and CJX2 10 micromol/L (P>0.05). Accumulation of intracellular Rh123 was increased and efflux of intracellular Rh123 was decreased in a time-dependent manner from 0-100 min after CJX1 and CXJ2 at 10 micromol/L treatment. The inhibitory effect of CJX1 and CJX2 on P-gp function was reversible and remained even at 120 min after removal of CJX1 and CJX2 at 2.5 micromol/L from the medium. CONCLUSION: CJX1 and CJX2 exhibited a potent effect in the inhibition of P-gp function in vitro.     

罗格列酮改善糖耐量减退患者血管内皮细胞功能的临床研究

目的观察罗格列酮治疗对糖耐量减退（IGT）患者血管内皮功能的影响。方法应用高分辨率超声检测34例IGT患者在接受罗格列酮治疗前后检测血流介导的血管扩张变化率（FMD），同时检测罗格列酮治疗前后患者血浆c反应蛋白（CRP）水平的变化。结果血流介导的血管扩张（FMD）变化率：罗格列酮治疗前（7．6±2．9）％，治疗后（14．9±6．1）％；两组比较差异有统计学意义（P〈0．01）。罗格列酮治疗前血浆CRP值显著高于治疗后，（7．6±3．1）mg／L与（4．1±1．5）mg／L）（P〈0．05）。结论罗格列酮治疗可以改善IGT患者血管内皮功能障碍，同时可降低患者体内的炎性反应水平。     

MicroRNAs and vascular (dys)function

MicroRNAs (miRNAs) are small non-coding RNAs, that control diverse cellular functions by either promoting degradation or inhibition of target messenger RNA translation. An aberrant expression profile of miRNAs has been linked to human diseases, including cardiovascular dysfunction. This review summarizes the latest insights in the identification of vascular-specific miRNAs and their targets, as well as their roles and mechanisms in the vasculature. Furthermore, we discuss how manipulation of these miRNAs could represent a novel therapeutic approach in the treatment of vascular dysfunction.