Selective prostaglandin G/H synthase (PGHS)-2 inhibitors show greater inhibitory activities on human PGHS-2 than on murine PGHS-2 in intact cells

Excess eicosanoid formation during inflammation has been attributed to the expression of the gene coding for the inducible isoform of prostaglandin G/H synthase (PGHS-2). Human and murine PGHS-2 proteins differ in 73 out of the 604 amino acids. When comparing the inhibitory effects of a panel of PGHS-inhibitors in a whole cell human and murine PGHS-2 assay carried out under identical conditions, classical NSAIDs with the exception of aspirin and tenoxicam showed similar inhibitory effects on both human and murine PGHS-2 enzymes. However, the PGHS-2 selective inhibitors nimesulide, flosulide and NS398 showed a much greater inhibition of human PGHS-2. We suggest that these differences could be due to the genetic differences of human and murine PGHS-2. Formerly R&D Division of Hafslund Nycomed Pharma AG, Austria.     

原花青素对RAW264.7细胞膜相关前列腺素E2合成酶-1表达的影响

目的探讨原花青素对RAW264.7细胞膜相关前列腺素E2合成酶-1(mPGES-1)表达的影响。方法酶免疫测定法(EIA)检测原花青素对PGE2生成的影响,逆转录聚合酶链反应(RT-PCR)检测mPGES-1mRNA的表达,Western blotting检测mPGES-1蛋白的表达。结果脂多糖(LPS)可以促进RAW264.7细胞PGE2的生成同时上调mPGES-1mRNA和蛋白的表达,而原花青素(4、20 mg.L-1)下调LPS诱导的RAW264.7细胞mPGES-1mRNA和蛋白的表达,从而抑制LPS诱导的RAW264.7细胞PGE2的生成。结论原花青素在mRNA和蛋白水平抑制LPS诱导的RAW264.7细胞mPGES-1表达从而减少PGE2的合成,这可能是原花青素抗炎的机制之一。     

2-乙酰氨基芴诱导γH2AX焦点的形成

目的探讨DNA损伤剂2-乙酰氨基芴(2-AAF)是否可诱导γH2AX焦点的形成及γH2AX作为检测DNA损伤的一个新的特异指标的可能性。方法用2-AAF处理中国仓鼠CHL细胞,应用免疫荧光方法检测γH2AX焦点的形成,并通过中性彗星实验验证DNA损伤的程度。结果0.1,1,5和20mg·L-1的2-AAF都可使细胞核内γH2AX焦点数量及有γH2AX焦点生成的细胞数量增加,但只有20mg·L-12-AAF处理的细胞才出现明显的彗尾增长及有彗尾的细胞数量增加。另外,磷脂酰肌醇3-激酶(PI3K)家族抑制物渥曼青霉素可抑制2-AAF诱导的γH2AX焦点形成。结论2-AAF可通过激活PI3K家族成员使H2AX磷酸化,进而诱导γH2AX焦点的形成。γH2AX检测DNA损伤的敏感性优于彗星实验,因此,γH2AX有可能成为衡量DNA损伤程度的良好指标。     

Hsp70 expression and free radical release after exposure to non-thermal radio-frequency electromagnetic fields and ultrafine particles in human Mono Mac 6 cells

The contemporary urban environment has become increasingly complex in its composition, leading to discussions regarding possible novel health effects. Two factors that recently have received considerable attention are ultrafine particles (UFP; <0.1 microm) produced by combustion processes and emissions from wireless communication devices like mobile phones that emit in the radio-frequency (RF) part of the spectrum. Several studies have shown biological effects of both these exposures in various cell systems. Here we investigate if exposure to UFP (12-14 nm, 100 microg/ml) and RF-electromagnetic fields (EMF; 2 W/kg specific absorption rate (SAR); continuous wave (CW) or modulated (217Hz or GSM-nonDTX)), alone or in combination influences levels of the superoxide radical anion or the stress protein heat-shock protein (Hsp70) in the human monocyte cell line Mono Mac 6. Heat treatment (42-43 degrees C, 1h) was used as positive control for both stress reaction and for heat development in the RF exposure setup. Our results clearly show that Mono Mac 6 cells are capable to internalise UFP, and that this phagocytic activity is connected to an increased release of free radicals. This increase (40-45% above negative control) is stronger than the effect of heat treatment. On the other hand, none of the employed RF exposures showed any effects on free radical levels. Co-exposure of RF and UFP did not potentiate the UFP effect either. Our investigations showed a significantly increased Hsp70 expression level by heat treatment in a time-dependent manner, whereas UFP, RF, or UFP+RF were without any effect. Therefore, we conclude that in the investigated Mono Mac 6 cells, RF exposure alone or in combination with UFP cannot influence stress-related responses.     

Procainamide, a drug causing lupus, induces prostaglandin H synthase-2 and formation of T cell-sensitizing drug metabolites in mouse macrophages.

Procainamide (PA) may cause drug-induced lupus, and its reactive metabolites, hydroxylamine-PA (HAPA) and nitroso-PA, are held responsible for this. Here, we show that N-oxidation of PA to these metabolites can take place in macrophages and lead to formation of neoantigens that sensitize T cells. Murine peritoneal macrophages (PMvarphi), exposed to PA in vitro, generated neoantigens related to HAPA as indicated by (1) their capacity to elicit a specific recall response of HAPA-primed T cells in the adoptive transfer popliteal lymph node (PLN) assay and (2) the appearance of metabolite-bound protein in PA-pulsed PMvarphi, as determined by Western blot. Analysis of five phase I enzymes that might be responsible for HAPA formation by PMvarphi pointed to prostaglandin H synthase-2 (PGHS-2) as a likely candidate. Experimental evidence that PA can be oxidized to HAPA by PGHS was obtained by exposing PA to PGHS in vitro. The resulting metabolites were identified by mass spectral analysis and covalent protein binding in ELISA. In vitro, PA exposure of PMvarphi of slow acetylator A/J and fast acetylator C57BL/6 mice failed to show significant strain differences in enzyme mRNA expression, enzyme activities, or formation of HAPA-related neoantigens. By contrast, after long-term PA treatment in vivo only in slow acetylators the PMvarphi harbored HAPA-related neoantigens and T cells were sensitized to them. PMvarphi of fast acetylator C57BL/6 mice only contained HAPA-related neoantigens, and their T cells were only sensitized to them if, in addition to long-term PA treatment, their donors had received injections of phorbol myristate acetate (PMA), a known enhancer of oxidative enzymes in phagocytes. In conclusion, PA treatment leads to N-oxidation of PA by enzymes, in particular PGHS-2, present in antigen-presenting cells (APC) and, hence, to generation of neoantigens which sensitize T cells. The enhanced neoantigen formation and T cell sensitization seen in slow acetylators might be explained by their higher concentration of PA substrate that is available for extrahepatic N-oxidation in APC.     

蛇葡萄素改变Bcl-2/Bax表达和激活caspase-3诱导人肝癌细胞Bel-7402凋亡

目的探讨蛇葡萄素在体外诱导人肝癌细胞株Bel-7402的凋亡作用及其可能机制。方法以不同浓度的蛇葡萄素作用于体外培养的人肝癌细胞株Bel-7402,应用MTT法检测培养24、48和72h的细胞生长情况;荧光染色观察细胞核的形态学改变;琼脂糖凝胶电泳分析细胞DNA变化;流式细胞仪检测细胞凋亡率;Western blot检测细胞caspase-3、Bcl-2和Bax的表达情况。结果蛇葡萄素对Bel-7402细胞的生长有明显的增殖抑制作用,呈浓度和时间依赖性。24、48、72h的IC50值分别是89.6±16.1、36.2±6.5和15.3±3.0mg·L-1。经荧光染色后可观察到典型的凋亡小体。细胞DNA电泳后呈现出凋亡细胞典型的DNAl adder。流式细胞术检测细胞凋亡率呈时间和浓度依赖性。caspase-3和Bcl-2蛋白表达量逐渐降低,Bax蛋白表达量逐渐增加,呈明显的浓度依赖性。结论蛇葡萄素能诱导体外培养的人肝癌Bel-7402细胞凋亡,其作用具有时间和浓度依赖性。下调Bcl-2、上调Bax表达,活化caspase-3是蛇葡萄素诱导Bel-7402细胞凋亡的可能机制之一。     

A comparative study of Mono Mac 6 cells, isolated mononuclear cells and Limulus amoebocyte lysate assay in pyrogen testing

Pyrogen induced secretion of interleukin 6 (IL-6) in Mono Mac 6 (MM6) cells was measured. The ability of the MM6 cell culture to detect pyrogens was compared to the Limulus amoebocyte lysate (LAL) test and isolated mononuclear cells (MNC). The detection limit of MM6 for lipopolysaccharide (LPS) and Staphylococcus aureus was comparable to that of MNC. Aspergillus niger and Candida albicans induced IL-6 in isolated MNC, but not in MM6. The detection limit for Salmonella typhimurium in the MM6 assay was comparable to that of the LAL assay. As expected, S. aureus and C. albicans did not show any LAL activity. A. niger and Influenza virus showed some activity in the LAL test, but could not be detected by MM6 cells. In conclusion, the MM6 assay is a good supplement to the current pyrogen assays for detection of LPS, S. aureus and S. typhimurium, but the MM6 assay could not detect A. niger, C. albicans and Influenza virus.     

合江佛手挥发油调控Bcl-2/Bax蛋白表达诱导人恶性胶质瘤U87细胞凋亡

目的:研究合江佛手挥发油诱导人恶性胶质瘤U87细胞凋亡及对凋亡相关因子Bcl-2和Bax蛋白表达的影响.方法:采用不同浓度的合江佛手挥发油作用于人乳腺癌细胞MCF-7、人恶性胶质瘤细胞U87、人肝癌细胞HepG2、人肺癌细胞A549,以CCK-8法(Cell Counting Kit-8 assay)筛选体外抗肿瘤活性...     

A test system for leukotriene synthesis inhibitors based on the in-vitro differentiation of the human leukemic cell lines HL-60 and Mono Mac 6

Differentiation of HL-60 cells along the granulocytic lineage by DMSO in the presence of transforming growth factor-β and low concentrations of 1,25-dihydroxyvitamin D₃ leads to the upregulation of 5-lipoxygenase activity in 100,000 g supernatants and intact cells to levels which are comparable to normal granulocytes. Similarly, differentiation of the human monocytic cell line Mono Mac 6 by 1,25-dihydroxyvitamin D₃ and transforming growth factor-β strongly upregulates the 5-lipoxygenase pathway. Here, we describe an assay system for leukotriene biosynthesis inhibitors which is based on the in-vitro differentiation of HL-60 and Mono Mac 6 cells. Different leukotriene biosynthesis inhibitors like the nonredox type inhibitor ZM 230487, the redox type inhibitor BW A4C and the FLAP inhibitor MK886 were tested and the results were compared with an assay system based on normal human granulocytes. ZM 230487, BWA4C and MK886 showed similar potencies in these cell lines as compared to normal leukocytes. Thus, the in-vitro differentiation of HL-60 and Mono Mac 6 cells provides an excellent model for the screening of drugs affecting the 5-lipoxygenase pathway. Received: 9 April 1997 / Accepted: 20 June 1997     

Atorvastatin reduces the expression of prostaglandin E2 receptors in human carotid atherosclerotic plaques and monocytic cells: potential implications for plaque stabilization

Prostaglandin E2 (PGE2), the product of cyclooxygenase-2 (COX-2) and prostaglandin E synthase-1 (mPGES-1), acts through its receptors (EPs) and induces matrix metalloproteinase (MMP) expression, which may favor the instability of atherosclerotic plaques. The effect of statins on EPs expression has not been previously studied. The aim of this study was to investigate the effect of atorvastatin (ATV, 80 mg/d, for one month) on EP expression in plaques and peripheral blood mononuclear cells (PBMC) of patients with carotid atherosclerosis. In addition, we studied the mechanisms by which statins could modulate EPs expression on cultured monocytic cells (THP-1) stimulated with proinflammatory cytokines (IL-1beta and TNF-alpha). Patients treated with atorvastatin showed reduced EP-1 (14 +/- 1.8% versus 26 +/- 2%; P < 0.01), EP-3 (10 +/- 1.5% versus 26 +/- 1.5%; P < 0.05), and EP-4 expression (10 +/- 4.1% versus 26.6 +/- 4.9%; P < 0.05) in atherosclerotic plaques (immunohistochemistry), and EP-3 and EP-4 mRNA expression in PBMC (real time PCR) in relation to non-treated patients. In cultured monocytic cells, atorvastatin (10 micromol/L) reduced EP-1/-3/-4 expression, along with COX-2, mPGES-1, MMP-9, and PGE2 levels elicited by IL-1beta and TNF-alpha. Similar results were noted with aspirin (100 micromol/L), dexamethasone (1 micromol/L), and the Rho kinase inhibitors Y-27632 and fasudil (10 micromol/L both). The effect of atorvastatin was reversed by mevalonate, farnesyl pyrophosphate, and geranylgeranyl pyrophosphate. On the whole, we have shown that atorvastatin reduces EPs expression in atherosclerotic plaques and blood mononuclear cells of patients with carotid stenosis and in cultured monocytic cells. The inhibition of EP receptors could explain, at least in part, some of the mechanisms by which statins could modulate the COX-2/mPGES-1 proinflammatory pathway and favor plaque stabilization in humans.     

Heme oxygenase-1 induction modulates microsomal prostaglandin E synthase-1 expression and prostaglandin E2 production in osteoarthritic chondrocytes

Pro-inflammatory cytokines such as interleukin-1β (IL-1β) may participate in the pathogenesis of cartilage damage in osteoarthritis (OA) through the production of catabolic enzymes and inflammatory mediators. Induction of heme oxygenase-1 (HO-1) has previously been shown to exert anti-inflammatory effects in different cell types. We have investigated whether HO-1 induction may modify chondrocyte viability and the production of relevant mediators such as oxidative stress and prostaglandin E₂ (PGE₂) elicited by IL-1β in OA chondrocytes. Chondrocytes were isolated from OA cartilage and used in primary culture. Cells were stimulated with IL-1β in the absence or presence of the HO-1 inducer cobalt protoporphyrin IX (CoPP). Gene expression was assessed by quantitative real-time PCR, protein levels by ELISA and Western blot, apoptosis by laser scanning cytometry using annexin V-FITC and TUNEL assays, and oxidative stress by LSC with dihydrorhodamine 123. HO-1 induction by CoPP enhanced chondrocyte viability and aggrecan content while inhibiting apoptosis and oxidative stress generation. PGE₂ is produced in OA chondrocytes stimulated by IL-1β by the coordinated induction of cyclooxygenase-2 and microsomal PGE synthase 1 (mPGES-1). The production of PGE₂ was decreased by HO-1 induction as a result of diminished mPGES-1 protein and mRNA expression. Transfection with HO-1 small interfering RNA counteracted CoPP effects. In addition, the activation of nuclear factor-κB and early growth response-1 was significantly reduced by CoPP providing a basis for its anti-inflammatory effects. These results confirm the protective role of HO-1 induction in OA chondrocytes and suggest the potential interest of this strategy in degenerative joint diseases.     

Effects of a prostaglandin F2alpha derivative glaucoma drug on EGF expression and E-cadherin expression in a corneal epithelial cell line

Abstract

Purpose: We examined the effects of travoprost on cell proliferation-related signals and E-cadherin expression in vitro and in situ in order to obtain evidence to support the hypothesis that topical travoprost impairs the integrity of the corneal epithelium.

Methods: A human corneal epithelial cell culture was treated with travoprost (0.4?mg/ml) and/or PD168393 (an EGF receptor inhibitor, 10?μM). The culture was then processed for cell proliferation, an mRNA expression analysis of epidermal growth factor (EGF) and E-cadherin, and protein expression analysis of E-cadherin by immunocytochemistry and Western blotting. The eyes of C57/BL6 mice were incubated in serum-free medium plus travoprost (0.4?mg/ml) and/or PD168393 (10?μM). After being cultured for 24?h, the expression patterns of phospho-EGFR, phospho-ERK, E-cadherin, and Ki67 were immunohistochemically examined in paraffin sections.

Results: The addition of travoprost up-regulated EGF mRNA expression and cell proliferation in the corneal epithelial cell culture, and this was cancelled by the addition of PD168393. This FP agonist also decreased E-cadherin expression levels in the cell–cell contact zone, and this was cancelled by the addition of PD168393. In the organ culture, the addition of travoprost to the medium up-regulated the expression of phospho-EGFR and phospho-ERK as well as cell proliferation, and down-regulated the expression of E-cadherin in the corneal epithelium, particularly in basal cells, whereas PD168393 reversed these effects.

Conclusions: Travoprost activates epithelial cell proliferation by up-regulating an EGF-related signal in association with the suppression of E-cadherin localization in the cell–cell contact zone. Modulation of the EGF signal may be a strategy to minimize the negative impact of this mitogen on reformation of corneal barrier function during epithelial renewal.     

Characteristics of 7 beta-hydroxycholesterol-induced cell death in a human monocytic blood cell line, U937, and a human hepatoma cell line, HepG2.

Oxysterols have been shown in a number of cell lines to induce apoptosis by a mechanism as yet unclear. The induction of apoptosis by certain agents has been associated with the generation of oxidative stress and the depletion of the endogenous antioxidant, glutathione, which may result in cytochrome c release and caspase activation. The aim of the present study was to determine whether 7 beta-hydroxycholesterol (7 beta-OH) alters glutathione levels or the activities of catalase, superoxide dismutase (SOD) or caspase-3 in association with cell death in either the U937 or the HepG2 cell lines. 7 beta-OH, which induced significant apoptosis at 12 h in the U937 cell line, was shown to cause a significant decrease in glutathione levels and an increase in the activity of SOD at this time point. An increase in caspase-3 activity was also observed in the U937 cell line following a 24-h incubation with 7 beta-OH. Glutathione concentration, SOD activity and caspase-3 activity were unchanged in the HepG2 cell line, which underwent necrosis following incubation with 7 beta-OH. The activity of the enzyme catalase remained unchanged in both cell lines. These results provide evidence that the generation of an oxidative stress may be a significant event occurring during 7 beta-OH-induced apoptosis.     

Microcystin‐LR induces protein phosphatase 2A alteration in a human liver cell line

Microcystin‐LR (MC‐LR) is a potent inhibitor of protein phosphatases 1 and 2A, and has potent hepatotoxicity and tumor promotion activity. Numerous studies on MC‐LR toxicity have been conducted in rat hepatocytes, but few studies of the effects of microcystins on human hepatocytes have been done. In this study, HL7702 cells (a human normal liver cell line) were incubated in MC‐LR for 24 h. The existence of MC‐LR in HL7702 cells was confirmed. Furthermore, PP2A activity and the alteration of PP2A subunits were assessed. The results show that PP2A activity decreased from the concentration of 1 μM MC‐LR, showing a concentration‐dependent decline, to about 34% at 10 μM MC‐LR. This activity undergone opposite change with alternations of phosphorylated Y307‐PP2A/C and PP2A/C subunit but showed same change with the alteration of the ratio of methylated L309‐PP2A/C to PP2A/C. B55α, a regulatory subunit of PP2A, was slightly increases in cells treated with the highest concentration of MC‐LR (10 μM), and colocalized increasedly with rearranged‐microtubules after 1 μM MC‐LR exposure. However, the proportion of early apoptotic cells did not show any change at various concentration of MC‐LR for 24 h. To our knowledge, this is the first report showing MC‐LR‐induced alteration of PP2A phosphatase in human cultured hepatocytes, and the mechanism of action seems to be similar as described before in vitro. The alteration of PP2A and microtubule seems to be the early event induced by MC‐LR exposure. © 2013 Wiley Periodicals, Inc. Environ Toxicol 29: 1236–1244, 2014.     

不同剂量前列腺素E2对H9c2心肌细胞肥大的影响

目的:研究前列腺素E2(PGE2)对H9c2心肌细胞的肥大作用,并分析其量效关系,为寻找抗心肌肥大的潜在靶点提供理论依据.方法:将H9c2心肌细胞分为空白对照组(C组)和PGE2处理组,PGE2处理组又分为小剂量PGE2组(D1组)、中剂量PGE2组(D2组)和大剂量PGE2组(D3组).各组细胞培养液中PGE2终浓度分别为0、0.1、1及10 μmol/L.给药孵育48 h后,利用荧光显微镜观察大鼠H9c2心肌细胞形态及体积;通过测量细胞直径大小、BCA法测定细胞总蛋白含量来确定心肌细胞是否肥大;RT-PCR技术测量心钠肽(Atrial natriuretic peptide,ANP)、脑钠肽(Brain natriuretic peptide,BNP)mRNA的表达水平,以此判断是否发生病理性肥大.结果:与C组比较,免疫荧光显示D1组、D2组及D3组细胞形态改变、体积增大;细胞直径及总蛋白含量显著增加(P＜0.05),不同剂量PGE2组间亦具有统计学差异(P＜0.05);D2组及D3组较C组细胞内ANP、BNP mRNA表达水平显著增高(P＜0.05).结论:PGE2可剂量依赖地诱导H9c2心肌细胞肥大,较大剂量PGE2引发心肌细胞病理性肥大.抑制PGE2合成有望为抑制心肌肥大提供靶点.     

Osthole induces G2/M cell cycle arrest and apoptosis in human hepatocellular carcinoma HepG2 cells

Context: Osthole [7-methoxy-8-(3-methyl-2-butenyl) coumarin] isolated from the fruit of Cnidium monnieri (L.) Cuss, one of the commonly used Chinese medicines listed in the Shennong’s Classic of Materia Medica in the Han Dynasty, had remarkable antiproliferative activity against human hepatocellular carcinoma HepG2 cells in culture.

Objectives: This study evaluated the effects of osthole on cell growth, nuclear morphology, cell cycle distribution, and expression of apoptosis-related proteins in HepG2 cells.

Materials and methods: Cytotoxic activity of osthole was determined by the MTT assay at various concentrations ranging from 0.004 to 1.0?µmol/ml in HepG2 cells. Cell morphology was assessed by Hoechst staining and fluorescence microscopy. Apoptosis and cell-cycle distribution was determined by annexin V staining and flow cytometry. Apoptotic protein levels were assessed by Western blot.

Results: Osthole exhibited significant inhibition of the survival of HepG2 cells and the half inhibitory concentration (IC₅₀) values were 0.186, 0.158 and 0.123?µmol/ml at 24, 48 and 72?h, respectively. Cells treated with osthole at concentrations of 0, 0.004, 0.02, 0.1 and 0.5?μmol/ml showed a statistically significant increase in the G2/M fraction accompanied by a decrease in the G0/G1 fraction. The increase of apoptosis induced by osthole was correlated with down-regulation expression of anti-apoptotic Bcl-2 protein and up-regulation expression of pro-apoptotic Bax and p53 proteins.

Conclusion: Osthole had significant growth inhibitory activity and the pro-apoptotic effect of osthole is mediated through the activation of caspases and mitochondria in HepG2 cells. Results suggest that osthole has promising therapeutic potential against hepatocellular carcinoma.