Reduced Cyclooxygenase-2 Expression Research Articles

Arterial stiffness induces remodeling phenotypes in pulmonary artery smooth muscle cells via YAP/TAZ-mediated repression of cyclooxygenase-2.

Pulmonary arterial stiffness is an independent risk factor for mortality in pulmonary hypertension (PH) and plays a critical role in PH pathophysiology. Our laboratory has recently demonstrated arterial stiffening early in experimental PH, along with evidence for a mechanobiological feedback loop by which arterial stiffening promotes further cellular remodeling behaviors (Liu F, Haeger CM, Dieffenbach PB, Sicard D, Chrobak I, Coronata AM, Suárez Velandia MM, Vitali S, Colas RA, Norris PC, Marinković A, Liu X, Ma J, Rose CD, Lee SJ, Comhair SA, Erzurum SC, McDonald JD, Serhan CN, Walsh SR, Tschumperlin DJ, Fredenburgh LE. JCI Insight 1: e86987, 2016). Cyclooxygenase-2 (COX-2) and prostaglandin signaling have been implicated in stiffness-mediated regulation, with prostaglandin activity inversely correlated to matrix stiffness and remodeling behaviors in vitro, as well as to disease progression in rodent PH models. The mechanism by which mechanical signaling translates to reduced COX-2 activity in pulmonary vascular cells is unknown. The present work investigated the transcriptional regulators Yes-associated protein (YAP) and WW domain-containing transcription regulator 1 (WWTR1, a.k.a., TAZ), which are known drivers of downstream mechanical signaling, in mediating stiffness-induced changes in COX-2 and prostaglandin activity in pulmonary artery smooth muscle cells (PASMCs). We found that YAP/TAZ activity is increased in PAH PASMCs and experimental PH and is necessary for the development of stiffness-dependent remodeling phenotypes. Knockdown of YAP and TAZ markedly induces COX-2 expression and downstream prostaglandin production by approximately threefold, whereas overexpression of YAP or TAZ reduces COX-2 expression and prostaglandin production to near undetectable levels. Together, our findings demonstrate a stiffness-dependent YAP/TAZ-mediated positive feedback loop that drives remodeling phenotypes in PASMCs via reduced COX-2 and prostaglandin activity. The ability to interrupt this critical mechanobiological feedback loop and enhance local prostaglandin activity via manipulation of YAP/TAZ signaling presents a highly attractive novel strategy for the treatment of PH.

In vitro investigation on the mechanism of spleen tyrosine kinase-nuclear factor kappa B signalling inducing cyclooxygenase-2 up-regulation in cancer pain caused by oral cancer associated macrophage

Background: The mechanism of oral cancer related pain is still unclear. Objectives: To explore the mechanism of cyclooxygenase-2 (COX-2) up-regulation in oral cancers associated macrophage via molecular biology techniques and primary culture of murine macrophage; and find a new way for cancer pain control. Methods: Murine macrophage was induced by M-CSF and Cal27 conditional medium. Purity of the macrophage was detected by CD68 immunofluorescence staining. Inhibitors of spleen tyrosine kinase (Syk) and nuclear factor kappa B (NFκB) were adopted to inhibit these pathways. Real-time polymerase chain reaction and western blot was adopted to detect the alterations on COX-2 and pathway related proteins. Findings and Conclusion: All the induced cells specifically express CD68. Cal27 conditional medium could significantly induce COX-2 expression (P < 0.001). Inhibition of Syk pathway attenuated the phosphorylation of NFκB-P65 and reduce COX-2 expression (P < 0.01); and inhibition of NFκB pathway had no effects on Syk phosphorylation but significantly inhibit COX-2 up-regulation (P < 0.01). Syk-NFκB is responsible for COX-2 overexpression in oral cancer associated macrophages. Targeting this pathway might be a new way for oral cancer related cancer pain control.

Thymoquinone suppresses migration of LoVo human colon cancer cells by reducing prostaglandin E2 induced COX-2 activation.

AIMTo identify potential anti-cancer constituents in natural extracts that inhibit cancer cell growth and migration.METHODSOur experiments used high dose thymoquinone (TQ) as an inhibitor to arrest LoVo (a human colon adenocarcinoma cell line) cancer cell growth, which was detected by cell proliferation assay and immunoblotting assay. Low dose TQ did not significantly reduce LoVo cancer cell growth. Cyclooxygenase 2 (COX-2) is an enzyme that is involved in the conversion of arachidonic acid into prostaglandin E2 (PGE2) in humans. PGE2 can promote COX-2 protein expression and tumor cell proliferation and was used as a control.RESULTSOur results showed that 20 μmol/L TQ significantly reduced human LoVo colon cancer cell proliferation. TQ treatment reduced the levels of p-PI3K, p-Akt, p-GSK3β, and β-catenin and thereby inhibited the downstream COX-2 expression. Results also showed that the reduction in COX-2 expression resulted in a reduction in PGE2 levels and the suppression of EP2 and EP4 activation. Further analysis showed that TG treatment inhibited the nuclear translocation of β-catenin in LoVo cancer cells. The levels of the cofactors LEF-1 and TCF-4 were also decreased in the nucleus following TQ treatment in a dose-dependent manner. Treatment with low dose TQ inhibited the COX-2 expression at the transcriptional level and the regulation of COX-2 expression efficiently reduced LoVo cell migration. The results were further verified in vivo by confirming the effects of TQ and/or PGE2 using tumor xenografts in nude mice.CONCLUSIONTQ inhibits LoVo cancer cell growth and migration, and this result highlights the therapeutic advantage of using TQ in combination therapy against colorectal cancer.

Augmented Contractility to Noradrenaline in Femoral Arteries from the Otsuka Long-Evans Tokushima Fatty Rat, a Model of Type 2 Diabetes

Although vasculopathies may occur systemically, there are few reports regarding femoral arteries of type 2 diabetes. Here, we investigated whether contractile response to noradrenaline in femoral arteries would change in type 2 diabetic male Otsuka Long-Evans Tokushima Fatty (OLETF) rat at the chronic stage of disease (1 year old) versus age-matched control Long-Evans Tokushima Otsuka (LETO) rat. OLETF rat exhibited hyperglycemia, hypertension, hyperlipidemia, and hypoinsulinemia compared to age-matched LETO rat. Noradrenaline-induced contraction was increased in femoral arteries in OLETF rats compared with LETO rats whereas serotonin- or phenylephrine-induced contractions were similar between these two animals. Acetylcholine- and sodium nitroprusside-induced relaxations were similar between the two groups. Very small relaxations in femoral arteries induced by clonidine and isoprenaline were obtained in LETO but not OLETF group. Noradrenaline-induced contraction was enhanced by treatment with NG-nitro-L-arginine (L-NNA), a nitric oxide synthase (NOS) inhibitor, and the between-group difference of contraction was eliminated by such treatment. Indomethacin, a non-selective cyclooxygenase (COX) inhibitor, reduced noradrenaline-induced contraction in both groups, whereas the contraction was greater in OLETF group versus LETO. Femoral arterial protein expression of endothelial NOS, COX-1, and superoxide dismutases were similar between the two groups, whereas reduction of COX-2 expression was seen in OLETF group compared with LETO. Increased contractile responsiveness to noradrenaline is seen in OLETF rat femoral artery and this may be due to reduction of suppressive effect of NO.

WITHDRAWN: Upregulation of HINT2 Inhibits Non-Small Cell Lung Cancer Cell Invasion Via COX-2/PGE₂-Mediated Activation of ß-catenin Signaling.

Histidine triad nucleotide binding protein 2 (HINT2) belongs to a HIT superfamily. It is ubiquitous and can be detectedin all forms of life. Recently, this protein has been reported to function as a tumor suppressor in some kind of cancers. However, little is known about its precise role in non-small cell lung cancer (NSCLC). In the present study, we explored the effects of HINT2 on the invasive potential of NSCLC cells. Our results showed that the expression of HINT2 was reduced in NSCLC tissues and cell lines. Up-regulation of HINT2 inhibited NSCLC cell invasion in vitro and tumor metastasis in vivo. We also found that the inhibitory effect of HINT2 on NSCLC cell invasion was associated with reduction of COX-2 expression. In addition, our further investigation on the underlying mechanisms demonstrated that up-regulation of HINT2 inhibited NSCLC cell invasion via COX-2/PGE₂-mediated activation of ß-catenin signaling. In conclusion, we presented evidence that HINT2 exerted a tumor-suppression effect on the progression of NSCLC. Thus, HINT2 might be a promising molecular target for treatment of NSCLC.

Effects of celecoxib and L-NAME on apoptosis and cell cycle ofMCF-7 CD44+/CD24–/low subpopulation

Recent studies have reported that cancer stem cells (CSCs) play a pivotal role in treatment failure, causing cancer recurrence. Here, we investigated the effects of L-NAME (an iNOS inhibitor) and celecoxib (a selective COX-2 inhibitor) on CSC-like cells (CSC-LCs) and their parental cells. Breast CSC-LCs derived from the MCF-7 cell line were sorted and characterized with the CD44+/CD24-/low phenotype. After isolation, the percentage of the subpopulation expressing CD44+/CD24-/low biomarkers increased considerably from 0.96% to 28.6%. Use of L-NAME and celecoxib showed antiproliferative activity towards both MCF-7 and CSC-LCs. Although celecoxib enhanced apoptotic cell death, the CSC-LC population was more resistant than parental cells. Moreover, L-NAME was less effective at inducing apoptosis, suggesting an involvement of different mechanisms of cell death. L-NAME caused cell cycle arrest in the S-phase in CSC-LCs, while celecoxib induced G0/G1 arrest in CSC-LCs and their parental cells. Immunocytochemistry results demonstrated that L-NAME had a similar potency to attenuate iNOS expression in MCF-7 and CSC-LCs; however, celecoxib reduced COX-2 expression in MCF-7 cells. The results show the crucial role of NOS and COX-2 in the maintenance of CD44+/CD24-/low breast CSC-LCs and suggest that L-NAME and celecoxib could have clinical implication in combination therapy.

In vitro investigation on the mechanism of cyclooxygenase-2 upregulation induced by spleen tyrosine kinase-nuclear factor κB signaling in cancer pain caused by oral cancer-associated macrophage

This study explores the mechanism of cyclooxygenase-2 (COX-2) upregulation in oral cancers associated with macrophage by using molecular biology techniques and primary culture of murine macrophage. Murine macrophage was induced by macrophage colony-stimulating factor (M-CSF) and Cal27 conditional medium (CM). Purity of the macrophage was detected through CD68 immunofluorescence staining. Inhibitors of spleen tyrosine kinase (Syk) and nuclear factor κB (NFκB) were used to inhibit these pathways. In addition, real-time polymerase chain reaction and Western blot analysis were used to detect alterations in COX-2 and pathway-related proteins. All of the induced cells specifically expressed CD68. Cal27 CM could significantly induce COX-2 expression (P<0.001). Moreover, inhibition of Syk pathway attenuated NFκB-P65 phosphorylation and reduced COX-2 expression (P<0.01), and inhibition of NFκB pathway exerted no effects on Syk phosphorylation but significantly inhibited COX-2 upregulation (P<0.01). Syk-NFκB is responsible for COX-2 overexpression in oral cancer associated with macrophages. Targeting this pathway is possibly a new approach to control oral cancer-related pain. .

Polymeric black tea polyphenols (PBPs) inhibit benzo(a)pyrene and 4-(methylnitrosamino)-1-(3-pyridyl)-1- butanone-induced lung carcinogenesis potentially through down-regulation of p38 and Akt phosphorylation in A/J mice.

The aim of our study was to evaluate chemopreventive efficacy and possible mechanism of most abundant polyphenolic fraction in black tea, polymeric black tea polyphenols (PBPs), in experimental lung carcinogenesis model. Effect of 1.5% black tea derived PBPs on benzo(a)pyrene [B(a)P] and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) induced lung lesions were studied over 28 wks. Chemopreventive efficacy was studied using decrease in tumor incidence and/or multiplicity and/or delay in the latency period in A/J mice. Histopathological analysis of lung was carried out post-carcinogen treatment weeks to analyze the microscopic lung lesions. Inflammation, cell proliferation, and apoptosis markers along with signaling kinases like p38, Akt, and their phosphorylated forms were studied using immunoblotting and immunohistochemistry at 4th, 10th, and 18th wk post-carcinogen treatment. Administration of PBPs throughout the treatment period significantly decreased the multiplicity of surface tumors as well as microscopic lung lesions, including adenomas. Although tumor incidence and latency period remains unaffected, histopathological evaluation of lung at 6, 10, and 18 wks post- carcinogen treatment period showed decrease in tumor multiplicity which was also correlated with different molecular markers. Anti- inflammatory action of PBPs was demonstrated by reduced Cox-2 expression. PBPs down-regulated the B(a)P and NNK-induced cell proliferation (diminished PCNA expression, proliferation index, and Bcl-2 expression) and enhanced apoptosis (increased Bax expression and apoptotic index) potentially through phosphorylation of p38 and Akt. PBPs, most abundant polyphenolic component in the black tea, have chemopreventive effect through inhibition of inflammation, cellular proliferation, and induction of apoptosis possibly via modulation of signaling kinases. © 2016 Wiley Periodicals, Inc.

Pioglitazone Enhances the Beneficial Effects of Glucocorticoids in Experimental Nephrotic Syndrome.

Glucocorticoids are the primary therapy for nephrotic syndrome (NS), but have serious side effects and are ineffective in ~20–50% of patients. Thiazolidinediones have recently been suggested to be renoprotective, and to modulate podocyte glucocorticoid-mediated nuclear receptor signaling. We hypothesized that thiazolidinediones could enhance glucocorticoid efficacy in NS. We found that puromycin aminonucleoside-induced proteinuria in rats was significantly reduced by both high-dose glucocorticoids (79%) and pioglitazone (61%), but not low-dose glucocorticoids (25%). Remarkably, pioglitazone + low-dose glucocorticoids also reduced proteinuria (63%) comparably to high-dose glucocorticoids, whereas pioglitazone + high-dose glucocorticoids reduced proteinuria to almost control levels (97%). Molecular analysis revealed that both glucocorticoids and pioglitazone enhanced glomerular synaptopodin and nephrin expression, and reduced COX-2 expression, after injury. Furthermore, the glomerular phosphorylation of glucocorticoid receptor and Akt, but not PPARγ, correlated with treatment-induced reductions in proteinuria. Notably, clinical translation of these findings to a child with refractory NS by the addition of pioglitazone to the treatment correlated with marked reductions in both proteinuria (80%) and overall immunosuppression (64%). These findings together suggest that repurposing pioglitazone could potentially enhance the proteinuria-reducing effects of glucocorticoids during NS treatment.

Thermoresponsive nanospheres with independent dual drug release profiles for the treatment of osteoarthritis

Dual drug delivery of drugs with different therapeutic effects in a single system is an effective way to treat a disease. One of the main challenges in dual drug delivery is to control the release behavior of each drug independently. In this study, we devised thermo-responsive polymeric nanospheres that can provide simultaneous and independent dual drug delivery in the response to temperature change. The nanospheres based on chitosan oligosaccharide conjugated pluronic F127 grafting carboxyl group were synthesized to deliver kartogenin (KGN) and diclofenac (DCF) in a single system. To achieve the dual drug release, KGN was covalently cross-linked to the outer part of the nanosphere, and DCF was loaded into the inner core of the nanosphere. The nanospheres demonstrated immediate release of DCF and sustained release of KGN, which were independently controlled by temperature change. The nanospheres treated with cold temperature effectively suppressed lipopolysaccharide-induced inflammation in chondrocytes and macrophage-like cells. The nanospheres also induced chondrogenic differentiation of mesenchymal stem cells, which was further enhanced by cold shock treatment. Bioluminescence of the fluorescence-labeled nanospheres was significantly increased after cold treatment in vivo. The nanospheres suppressed the progression of osteoarthritis in treated rats, which was further enhanced by cold treatment. The nanospheres also reduced cyclooxygenase-2 expression in the serum and synovial membrane of treated rats, which were further decreased with cold treatment. These results suggest that the thermo-responsive nanospheres provide dual-function therapeutics possessing anti-inflammatory and chondroprotective effects which can be enhanced by cold treatment. Statement of SignificanceWe developed thermo-responsive nanospheres that can provide a useful dual-function of suppressing the inflammation and promoting chondrogenesis in the treatment of osteoarthritis. For a dual delivery system to be effective, the release behavior of each drug should be independently controlled to optimize their desired therapeutic effects. We employed rapid release of diclofenac for acute anti-inflammatory effects, and sustained release of kartogenin, a newly found molecule, for chondrogenic effects in this polymeric nanospheres. This nanosphere demonstrated immediate release of diclofenac and sustained release of kartogenin, which were independently controlled by temperature change. The effectiveness of this system to subside inflammation and regenerate cartilage in osteoarthritis was successful demonstrated through in vitro and in vivo experiments in this study. We think that this study will add a new concept to current body of knowledge in the field of drug delivery and treatment of osteoarthritis.

COX-2 expression correlation with invasion in human breast carcinomas and in cell line MDA-MB-231 in vitro

COX-2 expression by means of immunohistochemistry in 120 cases breast invasive ductal carcinomas and 60 cases benign lesions were compared with clinicopathological features and prognostic molecular markers. COX-2 role of invasiveness and chemotaxis in breast cancer cell line MDA-MB-231 by using small RNA interference (siRNA) plasmids to disrupt COX-2 expression in vitro were investigated. The results show that COX-2 immune positivity and percentage of positive cells in breast carcinomas were higher than those in benign lesions and positivity correlated significantly with HIF-1?, VEGF, the grading, metastasis and vascular invasion of carcinoma (p&lt;0.05). This study suggests that COX-2 overexpression correlates with poor clinicopathological parameters in breast cancers, and the reduction of COX-2 expression can obviously inhibit the invasion and chemotaxis of cancer cell line MDA-MB-231 using RNA interference. The findings of the present study suggest that COX-2 overexpression in breast cancer may be considered as a negative prognostic marker.&#x0D;

Steroidal glycosides from the roots of Cynanchum stauntonii and their effects on the expression of iNOS and COX-2

Six new steroidal glycosides, named stauntosides O-T (1–6), along with eight known compounds (7–14), were obtained from the 95% aqueous ethanol extract of the roots of Cynanchum stauntonii. Their chemical structures were elucidated by IR, HR ESI-MS/MS, 1H- and 13C NMR, 1H-1H COSY, HSQC, HSQC-TOCSY, and HMBC spectroscopic analyses, which showed interesting 13,14:14,15-disecopregnane-type or 14,15-secopregnane-type C21 steroidal glycosides. The glycosides’ anti-inflammatory effects were investigated by detecting the inhibitory effects of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) on RAW246.7 murine macrophage cells stimulated by lipopolysaccharide (LPS). Our results showed that compounds 1, 5, 8, 9, 11, and 13 could significantly inhibit iNOS expression, and compounds 5 and 7 could clearly reduce COX-2 expression in RAW246.7 cells stimulated by LPS compared to cells stimulated with LPS and not treated with other compounds. Thus, compounds 1, 5, 7–9, 11, and 13 have the potential to mediate anti-inflammatory effects, with compound 5 having a greater anti-inflammatory effect than the other compounds.

Anti-Inflammatory Effects of Ginsenoside Rg3 via NF-κB Pathway in A549 Cells and Human Asthmatic Lung Tissue.

Objective. There is limited information of the anti-inflammatory effects of Rg3 on inflamed lung cells and tissues. Therefore, we confirmed the anti-inflammatory mechanism of ginsenoside Rg3 in inflamed human airway epithelial cells (A549) and tissues whether Rg3 regulates nuclear factor kappa B (NF-κB) activity. Methods. To induce the inflammation, IL-1β (10 ng/ml) was treated to A549 cells for 4 h. The effects of Rg3 on NF-κB activity and COX-2 expression were evaluated by western blotting analysis in both IL-1β-induced inflamed A549 cell and human asthmatic airway epithelial tissues. Using multiplex cytokines assay, the secretion levels of NF-κB-mediated cytokines/chemokines were measured. Result. Rg3 showed the significant inhibition of NF-κB activity thereby reduced COX-2 expression was determined in both IL-1β-induced inflamed A549 cell and human asthmatic airway epithelial tissues. In addition, among NF-κB-mediated cytokines, the secretion levels of IL-4, TNF-α, and eotaxin were significantly decreased by Rg3 in asthma tissues. Even though there was no significant difference, IL-6, IL-9, and IL-13 secretion showed a lower tendency compared to saline-treated human asthmatic airway epithelial tissues. Conclusion. The results from this study demonstrate the potential of Rg3 as an anti-inflammatory agent through regulating NF-κB activity and reducing the secretion of NF-κB-mediated cytokines/chemokines.

Taurocholate Induces Cyclooxygenase-2 Expression via the Sphingosine 1-phosphate Receptor 2 in a Human Cholangiocarcinoma Cell Line

Cholangiocarcinoma (CCA) is a rare, but highly malignant primary hepatobiliary cancer with a very poor prognosis and limited treatment options. Our recent studies reported that conjugated bile acids (CBAs) promote the invasive growth of CCA via activation of sphingosine 1-phosphate receptor 2 (S1PR2). Cyclooxygenase-2 (COX-2)-derived prostaglandin E2 (PGE2) is the most abundant prostaglandin in various human malignancies including CCA. Previous studies have indicated that COX-2 was highly expressed in CCA tissues, and the survival rate of CCA patients was negatively associated with high COX-2 expression levels. It has also been reported that CBAs induce COX-2 expression, whereas free bile acids inhibit COX-2 expression in CCA mouse models. However, the underlying cellular mechanisms and connection between S1PR2 and COX-2 expression in CCA cells have still not been fully elucidated. In the current study, we examined the role of S1PR2 in conjugated bile acid (taurocholate, (TCA))-induced COX-2 expression in a human HuCCT1 CCA cell line and further identified the potential underlying cellular mechanisms. The results indicated that TCA-induced invasive growth of human CCA cells was correlated with S1PR2-medated up-regulation of COX-2 expression and PGE2 production. Inhibition of S1PR2 activation with chemical antagonist (JTE-013) or down-regulation of S1PR2 expression with gene-specific shRNA not only reduced COX-2 expression, but also inhibited TCA-induced activation of EGFR and the ERK1/2/Akt-NF-κB signaling cascade. In conclusion, S1PR2 plays a critical role in TCA-induced COX-2 expression and CCA growth and may represent a novel therapeutic target for CCA.

Sinomenine, a COX-2 inhibitor, induces cell cycle arrest and inhibits growth of human colon carcinoma cells in vitro and in vivo.

Certain non-steroidal anti-inflammatory drugs may possess anti-tumorigenic effects in certain cancer cell types. Sinomenine (SIN) is an alkaloid from Sinomenium acutum, a Chinese medicinal plant that inhibits inflammatory reactions and that has been used in the treatment of neuralgia and rheumatic diseases. In this study, we investigated the anticancer effects of SIN against colorectal cancer in vitro and in vivo, as well as the underlying mechanisms. The effects of SIN on proliferation, cell cycle progression and cyclooxygenase (COX)-2 expression were examined in human colorectal cancer-derived SW1116 cells. The in vivo effects of SIN were examined in a model of SW1116 tumor xenograft growth in athymic nude mice. Changes in COX-2 expression induced by the biological effects of SIN were analyzed by western blot analysis. The effects of SIN treatment on G1 phase cell cycle regulators in xenografts were analyzed by immunohistochemistry. Our findings demonstrate that SIN inhibits the proliferation of SW1116 cells by promoting their accumulation in the G1 phase, with concomitant suppression of COX-2 expression. Time- and dose-dependent inhibition of tumor growth and reduced toxicity were observed in nude mice administered daily intraperitoneal injections of SIN at doses of 25, 50 and 100 mg/kg. SIN-treated tumors also exhibited reduced COX-2 expression, a marked increase in Cip1/p21 protein levels and a decrease in the levels of cyclin D1 and cyclin E. SIN may be an effective chemopreventive agent against colorectal cancer. The growth inhibitory properties of SIN against colorectal cancer may be mediated via a COX-2 inhibitory effect and cell cycle arrest in the G1 phase.

The Tpl2 Kinase Regulates the COX-2/Prostaglandin E2 Axis in Adipocytes in Inflammatory Conditions.

Bioactive lipid mediators such as prostaglandin E2 (PGE2) have emerged as potent regulator of obese adipocyte inflammation and functions. PGE2 is produced by cyclooxygenases (COXs) from arachidonic acid, but inflammatory signaling pathways controlling COX-2 expression and PGE2 production in adipocytes remain ill-defined. Here, we demonstrated that the MAP kinase kinase kinase tumor progression locus 2 (Tpl2) controls COX-2 expression and PGE2 secretion in adipocytes in response to different inflammatory mediators. We found that pharmacological- or small interfering RNA-mediated Tpl2 inhibition in 3T3-L1 adipocytes decreased by 50% COX-2 induction in response to IL-1β, TNF-α, or a mix of the 2 cytokines. PGE2 secretion induced by the cytokine mix was also markedly blunted. At the molecular level, nuclear factor κB was required for Tpl2-induced COX-2 expression in response to IL-1β but was inhibitory for the TNF-α or cytokine mix response. In a coculture between adipocytes and macrophages, COX-2 was mainly increased in adipocytes and pharmacological inhibition of Tpl2 or its silencing in adipocytes markedly reduced COX-2 expression and PGE2 secretion. Further, Tpl2 inhibition in adipocytes reduces by 60% COX-2 expression induced by a conditioned medium from lipopolysaccharide (LPS)-treated macrophages. Importantly, LPS was less efficient to induce COX-2 mRNA in adipose tissue explants of Tpl2 null mice compared with wild-type and Tpl2 null mice displayed low COX-2 mRNA induction in adipose tissue in response to LPS injection. Collectively, these data established that activation of Tpl2 by inflammatory stimuli in adipocytes and adipose tissue contributes to increase COX-2 expression and production of PGE2 that could participate in the modulation of adipose tissue inflammation during obesity.

Poly-γ-glutamic acid induces apoptosis via reduction of COX-2 expression in TPA-induced HT-29 human colorectal cancer cells.

Poly-γ-glutamic acid (PGA) is one of the bioactive compounds found in cheonggukjang, a fast-fermented soybean paste widely utilized in Korean cooking. PGA is reported to have a number of beneficial health effects, and interestingly, it has been identified as a possible anti-cancer compound through its ability to promote apoptosis in cancer cells, although the precise molecular mechanisms remain unclear. Our findings demonstrate that PGA inhibits the pro-proliferative functions of the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), a known chemical carcinogen in HT-29 human colorectal cancer cells. This inhibition was accompanied by hallmark apoptotic phenotypes, including DNA fragmentation and the cleavage of poly (ADP-ribose) polymerase (PARP) and caspase 3. In addition, PGA treatment reduced the expression of genes known to be overexpressed in colorectal cancer cells, including cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS). Lastly, PGA promoted activation of 5' adenosine monophosphate-activated protein (AMPK) in HT-29 cells. Taken together, our results suggest that PGA treatment enhances apoptosis in colorectal cancer cells, in part by modulating the activity of the COX-2 and AMPK signaling pathways. These anti-cancer functions of PGA make it a promising compound for future study.

Artesunate inhibits the growth and induces apoptosis of human gastric cancer cells by downregulating COX-2.

Artesunate, a derivative of artemisinin isolated from Artemisia annua L., has been traditionally used to treat malaria, and artesunate has demonstrated cytotoxic effects against a variety of cancer cells. However, there is little available information about the antitumor effects of artesunate on human gastric cancer cells. In the present study, we investigated the antitumor effect of artesunate on human gastric cancer cells and whether its antitumor effect is associated with reduction in COX-2 expression. The effects of artesunate on the growth and apoptosis of gastric cancer cells were investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, flow cytometric analysis of annexin V–fluorescein isothiocyanate/propidium iodide staining, rhodamine 123 staining, and Western blot analysis. Results indicate that artesunate exhibits antiproliferative effects and apoptosis-inducing activities. Artesunate markedly inhibited gastric cancer cell proliferation in a time- and dose-dependent manner and induced apoptosis in gastric cancer cells a dose-dependent manner, which was associated with a reduction in COX-2 expression. Treatment with the selective COX-2 inhibitor celecoxib, or transient transfection of gastric cancer cells with COX-2 siRNA, also inhibited cell proliferation and induced apoptosis. Furthermore, the treatment with artesunate promoted the expression of proapoptotic factor Bax and suppressed the expression of antiapoptotic factor Bcl-2. In addition, caspase-3 and caspase-9 were activated, and artesunate induced loss of mitochondrial membrane potential, suggesting that the apoptosis is mediated by mitochondrial pathways. These results demonstrate that artesunate has an effect on anti-gastric cancer cells. One of the antitumor mechanisms of artesunate may be that its inhibition of COX-2 led to reduced proliferation and induction of apoptosis, connected with mitochondrial dysfunction. Artesunate might be a potential therapeutic agent for gastric cancer.

2'-Hydroxy-4-methylsulfonylchalcone enhances TRAIL-induced apoptosis in prostate cancer cells.

Prostate cancer is the most common malignant cancer in men and the second leading cause of cancer deaths. Previously, we have shown that 2'-hydroxy-4-methylsulfonylchalcone (RG003) induced apoptosis in prostate cancer cell lines PC-3 and DU145. Although tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a promising anticancer agent, some cancer cells are resistant to TRAIL treatment. PC-3 and LNCaP prostatic cancer cell lines have been reported to be resistant to TRAIL-induced apoptosis. Here, we show for the first time that RG003 overcomes TRAIL resistance in prostate cancer cells. RG003 can enhance TRAIL-induced apoptosis through DR5 upregulation and downregulation of Bcl-2, PI3K/Akt, NF-κB, and cyclooxygenase-2 (COX-2) survival pathways. When used in combined treatment, RG003 and TRAIL amplified TRAIL-induced activation of apoptosis effectors and particularly activation of caspase-8 and the executioner caspase-3, leading to increased poly-ADP-ribose polymerase cleavage and DNA fragmentation in prostate cancer cells. Furthermore, we showed that RG003 reduced COX-2 expression in cells. Previously, we showed that COX-2 was involved in resistance to an apoptosis mechanism; then, its inhibition by RG003 could render cells more sensitive to TRAIL treatment. We showed that nuclear factor-κB activation was inhibited after RG003 treatment. This inhibition was correlated with reduction in COX-2 expression and induction of apoptosis. Overall, we conclude, for the first time, that RG003 can enhance TRAIL-induced apoptosis in human prostate cancer cells. The significance of our in-vitro study with RG003 and TRAIL combined is very encouraging, suggesting the relevance of testing this combined treatment in xenograft animal models.

Paeonol exerts an anticancer effect on human colorectal cancer cells through inhibition of PGE₂ synthesis and COX-2 expression.

Cyclooxygenase-2 (COX-2) and its metabolite prostaglandin E2 (PGE2) can potentially affect most of the events in cancer development, including promotion of proliferation, resistance to apoptosis, angiogenesis, immune suppression and invasion. However, worldwide attention has predominantly centered on the cardiovascular toxicity of selective COX-2 inhibitors. Paeonol is a major active extract from the root bark of Paeonia suffruticosa Andrews with anti‑inflammatory, anti-oxidant, anti-allergic, anti-oxidation and antitumor effects. In the present study, we investigated the underlying mechanisms of paeonol in inducing apoptosis and aimed to ascertain whether its antitumor effect is associated with a reduction in COX-2 expression and a decrease in the levels of PGE2 in colorectal cancer cells. We observed that paeonol inhibited cell proliferation and induced apoptosis in a dose- and time-dependent manner in colorectal cancer cells, which was associated with a reduction in COX-2 expression and PGE2 synthesis. Treatment with the selective COX-2 inhibitor, celecoxib, or transient transfection of colorectal cancer cells with COX-2 siRNA, also inhibited cell proliferation and induced apoptosis. Western blot analysis showed that paeonol inhibited the activation of NF-κB, an upstream regulator of COX-2, and its translocation to the nucleus. Treatment with increasing doses of paeonol led to increased expression of pro-apoptotic factor Bax and decreased expression of anti-apoptotic factor Bcl-2. Caspase-3 and caspase-9 were activated, and paeonol induced loss of mitochondrial membrane potential, suggesting that the apoptosis induced by paeonol was mediated by mitochondrial pathways. In addition, paeonol significantly suppressed tumor growth in a xenograft tumor mouse model in a dose-dependent manner. Our findings indicate that paeonol exerts an antitumor effect on human colorectal cancer cells by inhibiting PGE2 production and COX-2 expression. We expect that paeonol may replace selective COX-2 inhibitors due to their toxic effects, and may offer a new strategy for the therapy of colorectal cancer.