scholarly journals Discovery of 3-Arylquinoxaline Derivatives as Potential Anti-Dengue Virus Agents

2019 ◽  
Vol 20 (19) ◽  
pp. 4786
Author(s):  
Chih-Hua Tseng ◽  
Cheng-Ruei Han ◽  
Kai-Wei Tang
Keyword(s):  
Dengue Virus ◽  
Messenger Rna ◽  
Active Sites ◽  
Hydrophobic Interactions ◽  
Biological Activities ◽  
Inhibitory Effect ◽  
Docking Studies ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Cox 2

We designed and synthesized a series of novel 3-arylquinoxaline derivatives and evaluated their biological activities as potential dengue virus (DENV) replication inhibitors. Among them, [3-(4-methoxyphenyl)quinoxalin-2-yl](phenyl)methanol (19a), [6,7-dichloro-3-(4-methoxyphenyl)quinoxalin-2-yl](phenyl)methanol (20a), and (4-methoxyphenyl)(3-phenylquinoxalin-2-yl)methanone (21b) were found to significantly inhibit the DENV RNA expression in Huh-7-DV-Fluc cells with a potency better than that of ribavirin. Compound 19a reduced DENV replication in both viral protein and messenger RNA (mRNA) levels in a dose-dependent manner and exhibited no significant cell cytotoxicity. Notably, compound 19a exhibited a half maximal effective concentration (EC50) value at 1.29 ± 0.74 μM. We further observed that the inhibitory effect of 19a on DENV replication was due to suppression of DENV-induced cyclooxygenase-2 (COX-2) expression. Docking studies also showed that 19a caused hydrophobic interactions at the active sites with Arg29, Glu31, Tyr116, Leu138, Pro139, Lys454, Arg455, and Gln529. The calculated lowest binding energy between the 19a and COX-2 was −9.10 kcal/mol. In conclusion, compound 19a might be a potential lead compound for developing an anti-DENV agent.

scholarly journals Role of Gonadotropin-Releasing Hormone as an Autocrine Growth Factor in Human Ovarian Surface Epithelium1

Endocrinology ◽  
2000 ◽  
Vol 141 (1) ◽  
pp. 72-80 ◽  
Author(s):  
Sung Keun Kang ◽  
Kyung-Chul Choi ◽  
Kwai Wa Cheng ◽  
Parimal S. Nathwani ◽  
Nelly Auersperg ◽  
...  
Keyword(s):  
Gnrh Agonist ◽  
Messenger Rna ◽  
Ovarian Surface Epithelium ◽  
Inhibitory Effect ◽  
Surface Epithelium ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Rt Pcr ◽  
Ovarian Surface ◽  
Ovarian Surface Epithelial

Abstract Epithelial ovarian cancer, which accounts for 80–90% of all ovarian cancers, is the most common cause of death from gynecological malignancies and is believed to originate from the ovarian surface epithelium. In the present study we investigated the expression of GnRH and its receptor in human ovarian surface epithelial (hOSE) cells and provided novel evidence that GnRH may have antiproliferative effects in this tissue. Using RT-PCR and Southern blot analysis, we cloned the GnRH and GnRH receptor (GnRHR) in hOSE cells. Sequence analysis revealed that GnRH and its receptor have sequences identical to those found in the hypothalamus and pituitary, respectively. To address whether GnRH regulates its own and receptor messenger RNA (mRNA), the cells were treated with different concentrations of the GnRH agonist (d-Ala6)-GnRH. Expression levels of GnRH and its receptor were investigated using quantitative and competitive RT-PCR, respectively. Interestingly, a biphasic effect was observed for the GnRH and GnRHR mRNA levels. High concentrations of the GnRH agonist (10−7 and 10−9m) decreased GnRH and GnRHR mRNA levels, whereas a low concentration (10−11m) resulted in up-regulation of GnRH and receptor mRNA levels. Treatment with the GnRH antagonist, antide, prevented the biphasic effects of the GnRH agonist in hOSE cells, confirming the specificity of the response. Furthermore, to investigate the physiological significance, we studied receptor-mediated growth regulatory effects of GnRH in human ovarian surface epithelial cells. The cells were treated with GnRH analogs, and the proliferative index of cells was measured using a [3H]thymidine incorporation assay. (d-Ala6)-GnRH had a direct inhibitory effect on the growth of hOSE cells in a time- and dose-dependent manner. This antiproliferative effect of the GnRH agonist was receptor mediated, as cotreatment of hOSE cells with antide abolished the growth inhibitory effects of the GnRH agonist. The results strongly suggest that GnRH can act as an autocrine/paracrine regulator in hOSE cells.

scholarly journals β-Patchoulene, isolated from patchouli oil, suppresses inflammatory mediators in LPS-stimulated RAW264.7 macrophages

2017 ◽  
Vol 15 (2) ◽  
pp. 136-141 ◽  
Author(s):  
Wen-Hao Yang ◽  
Yu-Hong Liu ◽  
Jia-Li Liang ◽  
Zhi-Xiu Lin ◽  
Qiu-Lin Kong ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Inflammatory Cytokines ◽  
Messenger Rna ◽  
Inflammatory Activity ◽  
Prostaglandin E ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Raw264.7 Macrophages ◽  
Cox 2 ◽  
Anti Inflammatory

β-Patchoulene (β-PAE) is a tricyclic sesquiterpene isolated from patchouli oil. According to our previous study, β-PAE has anti-inflammatory activity in vivo; however, its anti-inflammatory response still remains unconfirmed in vitro. Therefore, this study is committed to demonstrate the anti-inflammatory effect of β-PAE on lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. According to our results, pre-treatment with β-PAE significantly decreased the protein and messenger RNA (mRNA) levels of pro-inflammatory cytokines including tumor necrosis factor-α (TNF-α), interleukin (IL)-6, and IL-1β while increased the expressions of anti-inflammatory cytokines like IL-10 in a dose-dependent manner. In addition, real-time polymerase chain reaction (PCR) also revealed that β-PAE could interrupt the mRNA expressions of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) and thus decreased the levels of nitric oxide (NO) and prostaglandin E2 (PGE2) in LPS-stimulated RAW264.7 macrophages. In conclusion, these results indicated that β-PAE exerted potent anti-inflammatory activity by maintaining the balance between pro- and anti-inflammatory cytokines as well as suppressing iNOS and COX-2 signaling pathways.

scholarly journals Corticotropin-Releasing Factor Inhibits Luteinizing Hormone-Stimulated P450c17 Gene Expression and Androgen Production by Isolated Thecal Cells of Human Ovarian Follicles1

1998 ◽  
Vol 83 (2) ◽  
pp. 448-452
Author(s):  
H. F. Erden ◽  
I. H. Zwain ◽  
H. Asakura ◽  
S. S. C. Yen
Keyword(s):  
Gene Expression ◽  
Granulosa Cells ◽  
Inhibitory Effect ◽  
Corticotropin Releasing Factor ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Messenger Ribonucleic Acid ◽  
Estrogen Production ◽  
Thecal Cells ◽  
Crf System

Recently, we reported that the thecal compartment of the human ovary contains a CRF system replete with gene expression and protein for corticotropin-releasing factor (CRF), CRF-Receptor 1 (CRF-R1), and the blood-derived high affinity CRF-binding protein (CRF-BP). Granulosa cells are devoid of the CRF system. The parallel increases in intensity of CRF, CRF-R1, and 17α-hydroxylase messenger ribonucleic acid (mRNA) and proteins in thecal cells with follicular maturation suggest that the intraovarian CRF system may play an autocrine role regulating androgen biosynthesis, with a downstream effect on estrogen production by granulosa cells. The functionality of the ovarian CRF system may be conditioned by the relative presence of plasma-derived CRF-BP by virtue of its localization of protein, but not transcript in thecal cells and its ability to compete with CRF for the CRF receptor. To further these findings, in the present study we have examined the effect of CRF on LH-stimulated 17α-hydroxylase (P450c17) gene expression and androgen production by isolated thecal cells from human ovarian follicles (11–13 mm). During the 48-h culture, addition of LH (10 ng/mL) to the medium increased by 5- and 6-fold dehydroepiandrosterone and androstenedione production by thecal cells. Remarkably, the LH-stimulated, but not basal, androgen production was inhibited by CRF in a time- and dose-dependent manner. The half-maximal (ID50) effect dose of CRF occurred at 5 × 10−8 mol/L, and at a maximal concentration of 10−6 mol/L, CRF completely inhibited LH-stimulated androgen production. This inhibitory effect of CRF became evident at 12 h (45%), and by 24 h the effect was more pronounced, with a 70% reduction from baseline. As determined by Northern analyses, CRF dose dependently decreased LH-stimulated P450c17 mRNA levels, with a maximal inhibition of 85% P450c17 gene expression at a CRF concentration of 10−6 mol/L. With the addition of 10−6 mol/L of the antagonist α-helical CRF-(9–41), the inhibitory effect of CRF was partially reversed for both P450c17 mRNA (75%) and androgen production (50%), indicating the CRF-R1-mediated event. In conclusion, the present study demonstrated a potent inhibitory effect of CRF on LH-stimulated dehydroepiandrosterone and androstenedione production that appears to be mediated through the reduction of P450c17 gene expression. Thus, the ovarian CRF system may function as autocrine regulators for androgen biosynthesis in the thecal cell compartment to maintain optimal substrate for estrogen biosynthesis by granulosa cells. Further studies to define the role of CRF-BP in the endocrine modulation of the intraovarian CRF system are needed.

scholarly journals Oleifolioside A, a New Active Compound, Attenuates LPS-Stimulated iNOS and COX-2 Expression through the Downregulation of NF-κB and MAPK Activities in RAW 264.7 Macrophages

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Hai Yang Yu ◽  
Kyoung-Sook Kim ◽  
Young-Choon Lee ◽  
Hyung-In Moon ◽  
Jai-Heon Lee
Keyword(s):  
Nitric Oxide ◽  
Mapk Signaling ◽  
Binding Activity ◽  
Prostaglandin E ◽  
Raw 264.7 ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Raw 264.7 Macrophages ◽  
Dendropanax Morbifera ◽  
Cox 2

Oleifolioside A, a new triterpenoid compound isolated fromDendropanax morbiferaLeveille (D. morbifera), was shown in this study to have potent inhibitory effects on lipopolysaccharide (LPS-)stimulated nitric oxide (NO) and prostaglandin E2(PGE2) production in RAW 264.7 macrophages. Consistent with these findings, oleifolioside A was further shown to suppress the expression of LPS-stimulated inducible nitric oxide synthase (iNOS) and cyclooxigenase-2 (COX-2) in a dose-dependent manner at both the protein and mRNA levels and to significantly inhibit the DNA-binding activity and transcriptional activity of NF-κB in response to LPS. These results were found to be associated with the inhibition of the degradation and phosphorylation of IκB-αand subsequent translocation of the NF-κB p65 subunit to the nucleus. Inhibition of NF-κB activation by oleifolioside A was also shown to be mediated through the prevention of p38 MAPK and ERK1/2 phosphorylation. Taken together, our results suggest that oleifolioside A has the potential to be a novel anti-inflammatory agent capable of targeting both the NF-κB and MAPK signaling pathways.

Discovery of a Novel Small-Molecule Interleukin-6 Inhibitor through Virtual Screening Using Artificial Intelligence

2021 ◽  
Vol 18 ◽  
Author(s):  
Yoshiaki Sato ◽  
Ikuo Kashiwakura ◽  
Masaru Yamaguchi ◽  
Hironori Yoshino ◽  
Takeshi Tanaka ◽  
...  
Keyword(s):  
Artificial Intelligence ◽  
Small Molecule ◽  
Interleukin 6 ◽  
Inflammatory Diseases ◽  
Biological Activities ◽  
Inhibitory Effect ◽  
Dependent Manner ◽  
Cell Functions ◽  
Dependent Cell ◽  
Dose Dependent

Background: Interleukin-6 (IL-6) is a multifunctional cytokine involved in various cell functions and diseases. Thus far, several IL-6 inhibitors, such as, humanized monoclonal antibody have been used to block excessive IL-6 signaling causing autoimmune and inflammatory diseases. However, anti-IL-6 and anti-IL-6 receptor monoclonal antibodies have some clinical disadvantages, such as a high cost, unfavorable injection route, and tendency to mask infectious diseases. While a small-molecule IL-6 inhibitor would help mitigate these issues, none are currently available. Objective: The present study evaluated the biological activities of identified compounds on IL-6 stimulus. Methods: We virtually screened potential IL-6 binders from a compound library using INTerprotein’s Engine for New Drug Design (INTENDD®) followed by the identification of more potent IL-6 binders with artificial intelligence (AI)-guided INTENDD®. The biological activities of the identified compounds were assessed with the IL-6-dependent cell line 7TD1. Results: The compounds showed the suppression of IL-6-dependent cell growth in a dose-dependent manner. Furthermore, the identified compound inhibited expression of IL-6-induced phosphorylation of signal transducer and activator of transcription 3 in a dose-dependent manner. Conclusion: Our screening compound demonstrated an inhibitory effect on IL-6 stimulus. These findings may serve as a basis for the further development of small-molecule IL-6 inhibitors.

scholarly journals Protective effect of Cordyceps sinensis extract on lipopolysaccharide-induced acute lung injury in mice

2019 ◽  
Vol 39 (6) ◽  
Author(s):  
Shuiqiao Fu ◽  
Weina Lu ◽  
Wenqiao Yu ◽  
Jun Hu
Keyword(s):  
Acute Lung Injury ◽  
Lung Injury ◽  
Protective Effect ◽  
Weight Ratio ◽  
Cordyceps Sinensis ◽  
Myeloperoxidase Activity ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Tnf Α ◽  
Cox 2

Abstract Background: To study the protective effect of Cordyceps sinensis extract (Dong Chong Xia Cao in Chinese [DCXC]) on experimental acute lung injury (ALI) mice. Methods and results: ALI model was induced by intratracheal-instilled lipopolysaccharide (LPS, 2.4 mg/kg) in BALB/c male mice. The mice were administrated DCXC (ig, 10, 30, 60 mg/kg) in 4 and 8 h after receiving LPS. Histopathological section, wet/dry lung weight ratio and myeloperoxidase activity were detected. Bronchoalveolar lavage fluid (BALF) was collected for cell count, the levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) and nitric oxide (NO) in BALF was detected by ELISA, the protein and mRNA expression of nuclear factor-κB p65 (NF-κB p65), inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) in lung tissue was detected by Western blot and RT-PCR. The result showed that DCXC could reduce the degree of histopathological injury, wet/dry weight ratio (W/D ratio) and myeloperoxidase activity (P<0.05) with a dose-dependent manner. The increased number of total cells, neutrophils and macrophages in BALF were significantly inhibited by DCXC treatment (P<0.05). The increased levels of TNF-α, IL-1β, IL-6 and NO in BALF after LPS administration was significantly reduced by DCXC (P<0.05). In addition, the increased protein and mRNA levels of iNOS, COX-2 and NF-κB p65 DNA binding ability in LPS group were dose-dependently reduced by DCXC treatment (P<0.05). Conclusion: DCXC could play an anti-inflammatory and antioxidant effect on LPS-induced ALI through inhibiting NF-κB p65 phosphorylation, and the expression of COX-2 and iNOS in lung. The result showed that DCXC has a potential protective effect on the ALI.

scholarly journals Transforming Growth Factor-βs Inhibit Somatostatin Messenger Ribonucleic Acid Levels and Somatostatin Secretion in Hypothalamic Cells in Culture*

Endocrinology ◽  
1997 ◽  
Vol 138 (10) ◽  
pp. 4401-4409 ◽  
Author(s):  
M. Quintela ◽  
R. M. SeñarÍs ◽  
C. Diéguez
Keyword(s):  
Growth Factor ◽  
Messenger Rna ◽  
Transforming Growth Factor ◽  
Inhibitory Effect ◽  
Mrna Levels ◽  
Messenger Ribonucleic Acid ◽  
Cells In Culture ◽  
Somatostatin Secretion ◽  
Hypothalamic Cells ◽  
The Stability

Abstract Treatment of hypothalamic cells in monolayer culture with transforming growth factor-β1 (TGFβ1) significantly reduced both basal and cAMP-induced somatostatin messenger RNA (mRNA) levels and somatostatin secretion. This inhibitory effect was dose- and time-dependent and not mediated by glial cells, as it was also observed in glial-free hypothalamic cell cultures treated with cytosine arabinonucleoside. TGFβ2 and -β3 mimicked the actions of TGFβ1, which indicated that the three isoforms of the TGFβ family expressed in the central nervous system displayed similar effects on the somatostatinergic neurons. The blockade of synthesis of proteins with either cycloheximide or puromycin for 24 h prevented the inhibitory effect of TGFβ1 on somatostatin mRNA. This implied that the reduction of this mRNA by TGFβ1 required de novo protein synthesis. We next studied whether TGFβ1 acted at the transcriptional or posttranscriptional level by altering the stability of somatostatin mRNA. Examination of the rate of disappearance of somatostatin mRNA by Northern blot, after inhibition of mRNA transcription with either actinomycin D (AcD) or 5,6-dichloro-1β-ribofuranosyl benzimidazole revealed that TGFβ1 did reduce the stability of somatostatin mRNA. This effect was observed when we pretreated the cultures with TGFβ1 4 h before the addition of AcD, but not when we administered TGFβ1 simultaneously with AcD or 5,6-dichloro-1β-ribofuranosyl benzimidazole. Altogether these results demonstrated that the treatment of hypothalamic cells in culture with TGFβ1, TGFβ2, or TGFβ3 resulted in a decrease in somatostatin mRNA levels and somatostatin secretion. TGFβ1 reduced the steady state levels of somatostatin mRNA by inducing the synthesis of a protein (s), that appears to accelerate the degradation of the mRNA of somatostatin. Whether TGFβ1 has additional effects on the transcription of the somatostatin gene will require further study.

scholarly journals Regulation of c-jun gene expression in human T lymphocytes

Blood ◽  
1993 ◽  
Vol 81 (6) ◽  
pp. 1540-1548 ◽  
Author(s):  
D Chauhan ◽  
SM Kharbanda ◽  
E Rubin ◽  
BA Barut ◽  
A Mohrbacher ◽  
...  
Keyword(s):  
Gene Expression ◽  
T Cells ◽  
Messenger Rna ◽  
Jurkat Cells ◽  
Pokeweed Mitogen ◽  
Mrna Levels ◽  
Dependent Manner ◽  
B Cell Differentiation ◽  
Normal Peripheral Blood ◽  
Mrna Induction

Abstract The present studies have examined the effects of mitogens on induction of early response gene expression in normal peripheral blood T and Jurkat cells. Pokeweed mitogen (PWM) or anti-CD3 significantly increases c-jun messenger RNA (mRNA) levels in T cells. This transient PWM-related increase in c-jun transcripts is maximal after 15 to 30 minutes of exposure of T cells to PWM. PWM induces c-jun gene expression in a concentration-dependent manner. Moreover, PWM similarly induces expression of other genes coding for leucine zipper transcription factors, ie, jun-B and c-fos. Nuclear run on assays demonstrate that PWM treatment is associated with an increased rate of c-jun gene transcription. Transient expression assays with c-jun promoter fragments linked to the chloramphenicol acetyltransferase gene suggest that the PWM-induced increase in transcription is mediated by the AP-1 transcription factor complex. Moreover, treatment of T cells with actinomycin D to block further transcription before their culture with PWM suggests that the increase in c-jun gene expression by PWM is also regulated at least in part by a posttranscriptional mechanism. Cycloheximide does not alter c-jun mRNA induction by PWM. Finally, given that PWM induces B-cell differentiation in an interleukin-6 (IL- 6)-mediated, T-cell-dependent manner, the relationship of c-jun and IL- 6 gene expression in PWM-stimulated T cells was examined. The induction of IL-6 mRNA in T cells stimulated by PWM occurs after maximal induction of c-jun mRNA, at a time when the latter is no longer detectable. These findings suggest that PWM induces c-jun gene expression in T cells by a transcriptional and posttranscriptional mechanism and that AP-1 confers PWM inducibility of this gene. Because the IL-6 promoter has several potential transcriptional control elements, one of which is an AP-1-binding site, future experiments will evaluate the role of c-jun in the regulation of PWM-induced IL-6 synthesis by T cells.

scholarly journals Progesterone inhibits glucocorticoid-dependent aromatase induction in human adipose fibroblasts

1998 ◽  
Vol 158 (3) ◽  
pp. 401-407 ◽  
Author(s):  
M Schmidt ◽  
C Renner ◽  
G Loffler
Keyword(s):  
Adipose Tissue ◽  
Active Sites ◽  
Premenopausal Women ◽  
Human Adipose Tissue ◽  
Inhibitory Effect ◽  
Pcr Analysis ◽  
Aromatase Activity ◽  
Dependent Manner ◽  
Physiological Concentration ◽  
Intact Cells

In fibroblasts derived from human adipose tissue, aromatase induction is observed after exposure to 1 microM cortisol in the presence of serum or platelet-derived growth factor (PDGF). Progesterone suppresses this induction in a dose-dependent manner, 10 microM resulting in complete inhibition. A reduced cortisol concentration (0.1 microM) concomitantly reduces the progesterone concentration required for effective inhibition (10-100 nM). This effect of progesterone is specific, as neither the release of cellular enzymes nor aromatase induction by dibutyryl-cAMP, which acts independently from cortisol, are affected. However, the inhibitory effect of progesterone requires its presence throughout the induction period. Kinetic studies in intact cells reveal a reduced number of aromatase active sites upon progesterone treatment, whereas progesterone at near-physiological concentration (100 nM) does not inhibit aromatase activity in isolated microsomes. Semi-quantitative reverse transcriptase PCR analysis shows reduced amounts of aromatase mRNA in progesterone-treated cells, indicating specific inhibition of the glucocorticoid-dependent pathway of aromatase induction. The inhibitory effect of progesterone is not blocked by the anti-progestin ZK114043, excluding action via progesterone receptors and indicating competition for the glucocorticoid receptor. Progesterone must be considered a potential physiological inhibitor of glucocorticoid-dependent aromatase induction in adipose tissue. It is proposed that it is a suppressor of aromatase induction in adipose tissue in premenopausal women.

scholarly journals The Induction of Cyclooxygenase-2 in IL-1β-Treated Endothelial Cells is Inhibited by Prostaglandin E2 through cAMP

1999 ◽  
Vol 8 (6) ◽  
pp. 287-294 ◽  
Author(s):  
Pravit Akarasereenont ◽  
Kitirat Techatrisak ◽  
Sirikul Chotewuttakorn ◽  
Athiwat Thaworn
Keyword(s):  
Endothelial Cells ◽  
Biological Activities ◽  
Umbilical Vein ◽  
The Body ◽  
Prostaglandin E ◽  
Dependent Manner ◽  
Negative Feedback Regulation ◽  
Cox 2 ◽  
Arachidonic Acids ◽  
Cox 1

Prostaglandins (PGS) have numerous cardiovascular and inflammatory effects. Cyclooxygenase (COX), which exists as COX-1 and COX-2 isoforms, is the first enzyme in the pathway in which arachidonic acid is converted to PGs. Prostaglandin E2 (PGE2) exerts a variety of biological activities for the maintenance of local homeostasis in the body. Elucidation of PGE2 involvement in the signalling molecules such as COX could lead to potential therapeutic interventions. Here, we have investigated the effects of PGE2 on the induction of COX-2 in human umbilical vein endothelial cells (HUVEC) treated with interleukin-1β (IL-1β 1 ng/ml). COX activity was measured by the production of 6-keto-PGF1α, PGE2, PGF2α and thromboxane B2 (TXB2) in the presence of exogenous arachidonic acids (10 μM for 10 min) using enzyme immunoassay (EIA). COX-1 and COX-2 protein was measured by immunoblotting using specific antibody. Untreated HUVEC contained only COX-1 protein while IL-1β treated HUVEC contained COX-1 and COX-2 protein. PGE2 (3 μM for 24 h) did not affect on COX activity and protein in untreated HUVEC. Interestingly, PGE2 (3 μM for 24 h) can inhibit COX-2 protein, but not COX-1 protein, expressed in HUVEC treated with IL1 β. This inhibition was reversed by coincubation with forskolin (100 μM). The increased COX activity in HUVEC treated with IL-1β was also inhibited by PGE2 (0.03, 0.3 and 3 μM for 24 h) in a dose-dependent manner. Similarly, forskolin (10, 50 or 100 μM) can also reverse the inhibition of PGE2 on increased COX activity in IL-1β treated HUVEC. The results suggested that (i) PGE2 can initiate negative feedback regulation in the induction of COX-2 elicited by IL-1β in endothelial cells, (ii) the inhibition of PGE2 on COX-2 protein and activity in IL-1β treated HUVEC is mediated by cAMP and (iii) the therapeutic use of PGE2 in the condition which COX-2 has been involved may have different roles.

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