Inhibition of human neuroblastoma cell growth by CAY10404, a highly selective Cox-2 inhibitor

Mangiferin from Enicostemma littorale Blume with in silico and in vitro anti-inflammatory potential

The bioassay-guided fractionation of the extract of aerial parts of Enicostemma littorale resulted in two fractions 3 and 4 with moderate and potent antioxidant activity, respectively. The purification of fraction 3 gave swertiamarin (1), while the LCMS profile of fraction 4 unveiled the presence of another constituent along with swertiamarin. The extensive purification of fraction 4 led to the unusual isolation of mangiferin (2) from E. littorale. The uncommon isolation of mangiferin from E. littorale motivated us to conduct its in silico and in vitro screening as an anti-inflammatory agent. Both studies have proved mangiferin to be a promising anti-inflammatory molecule with a binding energy of -9.17 kcal/mol against Cyclooxygenase-2 protein and IC50 of 146.07 nanomolar. This study is the first report of the isolation of mangiferin, a xanthone glycoside from E. littorale.Communicated by Ramaswamy H. Sarma.

Role of Cyclooxygenase-2 Pathway in Creating an Immunosuppressive Microenvironment and in Initiation and Progression of Wilms' Tumor

Wilms' tumors (WT), which accountfor 6% of all childhood cancers, arise from dysregulated differentiation of nephrogenic progenitor cells from embryonic kidneys. Though there is an improvement in the prognosis of WT, still 10% of patients with WT die due to recurrence. Thus more effective treatment approaches are necessary. We previously characterized the inflammatory microenvironment in human WT and observed the robust expression of COX-2. The aim of this study was to extend our studies to analyze the role of COX-2 pathway components in WT progression using a mouse model of WT. Herein, COX-2 pathway components such as COX-2, HIF1-α, p-ERK1/2, and p-STAT3 were upregulated in mouse and human tumor tissues. In our RPPA analysis, COX-2 was up-regulated in M15 cells after Wt1 gene was knocked down. Flow cytometry analysis showed the increased infiltration of immune suppressive inflammatory cells such as pDC's and Treg cells in tumors. The chemotactic chemokines responsible for the infiltration of these cells were also induced in CCR5 and CXCR4 dependent manner respectively. The immunosuppressive cytokines IL-10, TGF-β, and TNF-α were also up-regulated. Furthermore, more pronounced Th2 and Treg induced cytokine response was observed than Th1 response in tumors. Basing on all these evidences it is speculated that COX-2 pathway may be a beneficial target for the treatment of WT. It may be most effective as an adjuvant therapy together with other inhibitors. Thus, our current study provides a good rationale for initiating animal studies to confirm the efficacy of COX-2 inhibitors in decreasing tumor cell growth in vivo.

Characterization of the inflammatory microenvironment and identification of potential therapeutic targets in wilms tumors

The role of inflammation in cancer has been reported in various adult malignant neoplasms. By contrast, its role in pediatric tumors has not been as well studied. In this study, we have identified and characterized the infiltration of various inflammatory immune cells as well as inflammatory markers in Wilms tumor (WT), the most common renal malignancy in children. Formalin-fixed paraffin-embedded blocks from tumors and autologous normal kidneys were immunostained for inflammatory immune cells (T cells, B cells, macrophages, neutrophils, and mast cells) and inflammatory markers such as cyclooxygenase-2 (COX-2), hypoxia-inducible factor 1α, phosphorylated STAT3, phosphorylated extracellular signal-related kinases 1 and 2, inducible nitric oxide synthase, nitrotyrosine, and vascular endothelial growth factor expression. Overall, we found that there was predominant infiltration of tumor-associated macrophages in the tumor stroma where COX-2 was robustly expressed. The other tumor-associated inflammatory markers were also mostly localized to tumor stroma. Hence, we speculate that COX-2-mediated inflammatory microenvironment may be important in WT growth and potential therapies targeting this pathway may be beneficial and should be tested in clinical settings for the treatment of WTs in children.

Silencing of the P2X(7) receptor enhances amyloid-β phagocytosis by microglia

P2X7 receptor (P2X7R) is an ATP-gated cation channel that promotes microglia activation and plays a critical role in the pathogenesis of Alzheimer's disease. Inhibiting P2X7R indirectly reduces the rate of amyloid-β (Aβ)-induced neurodegeneration by suppressing secretion of inflammatory factors from activated microglia. We used RNA interference to silence P2X7R in microglial cells in vitro and found it markedly increased microglial phagocytosis of Aβ1-42. Increased phagocytic activity was dependent on decreasing the rate of interleukin-1β release from microglia and required inhibition of the COX-2 pathway. Modulation of microglial phagocytosis and secretion via silencing P2X7R may be a promising therapeutic option for the treatment of Alzheimer's disease.

Calcineurin (CN) activation promotes apoptosis of glomerular podocytes both in vitro and in vivo

To determine the role of Gq signaling and calcineurin (CN) activation in promoting apoptosis of glomerular podocytes, constitutively active Gq [Gq(+)] or CN [CN(+)] proteins were introduced into cultured podocytes using protein transduction by tagging the proteins with the transactivator of transcription peptide. To investigate the role of CN in promoting podocyte apoptosis in vivo, a genetic model of type 1 diabetes mellitus (Akita mice) was treated with the CN inhibitor FK506. In cultured podocytes, Gq(+) stimulated nuclear translocation of nuclear factor of activated T cells (NFAT) family members, activated an NFAT reporter construct, and enhanced podocyte apoptosis in a CN-dependent fashion. CN(+) similarly promoted podocyte apoptosis, and apoptosis induced by either angiotensin II or endothelin-1 was blocked by FK506. Induction of apoptosis required NFAT-induced gene transcription because apoptosis induced by either Gq(+) or CN(+) was blocked by an inhibitor that prevented CN-dependent NFAT activation without affecting CN phosphatase activity. Podocyte apoptosis was mediated, in part, by the NFAT-responsive gene cyclooxygenase 2 (COX2) and prostaglandin E(2) generation because apoptosis induced by Gq(+) was attenuated by either COX2 inhibition or blockade of the Gq-coupled E-series prostaglandins receptor. The findings appeared relevant to podocyte apoptosis in diabetic nephropathy because apoptosis was significantly reduced in Akita mice by treatment with FK506. These data suggest that Gq stimulates CN and promotes podocyte apoptosis both in vitro and in vivo. Apoptosis requires NFAT-dependent gene transcription and is mediated, in part, by CN-dependent COX2 induction, prostaglandin E(2) generation, and autocrine activation of the Gq-coupled E-series prostaglandins receptor.

Effects of CAY10404 on the PKB/Akt and MAPK pathway and apoptosis in non-small cell lung cancer cells

BACKGROUND AND OBJECTIVE

Lung cancer is the most common cause of cancer death in men and women worldwide. The mechanism of cell death induced by CAY10404, a highly selective cyclooxygenase-2 inhibitor, was evaluated in three non-small cell lung cancer (NSCLC) cell lines (H460, H358, H1703).

METHODS

To measure the effects of CAY10404 on proliferation of NSCLC cells, 3 x 10(3) cells/well were plated in 96-well plates and allowed to adhere overnight at 37 degrees C. After treatment with CAY10404 for 3 days, cell proliferation was measured by the 3- (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. In the H460 NSCLC cells, evidence of apoptosis was sought using the terminal deoxynucleotidyl transferase deoxyuridine triphosphate (dUTP) nick end labelling (TUNEL) assay and western blot analysis.

RESULTS

Treatment with CAY10404 in the range of 10-100 microM caused dose-dependent growth inhibition, with an average 50% inhibitory concentration (IC(50)) of 60-100 micromol/L, depending on the cell line. Western blot analysis of CAY10404-treated cells showed cleavage of poly (ADP-ribose) polymerase (PARP) and procaspase-3, signifying caspase activity and apoptotic cell death. CAY10404 treatment inhibited the phosphorylation of Akt, glycogen synthase kinase-3beta and extracellular signal-regulated kinases 1/2 in H460 and H358 cells.

CONCLUSIONS

These results suggest that CAY10404 is a potent inducer of apoptosis in NSCLC cells, and that it may act by suppressing multiple protein kinase B/Akt and mitogen-activated protein kinase pathways.

Cyclooxygenase 2 pathway and its therapeutic inhibition in superantigen-induced toxic shock

Bacterial superantigens are a family of exotoxins that are the most potent T-cell activators known. Because of their ability to induce strong immune activation, superantigens have been implicated in a variety of diseases ranging from self-limiting food poisoning to more severe toxic shock syndrome (TSS) and have the potential to be used as agents of bioterrorism. Nonetheless, the precise molecular mechanisms by which T-cell activation by superantigens lead to acute systemic inflammatory response, multiple organ dysfunction, and ultimately death are unclear. Inadequate understanding of the pathogenesis has resulted in lack of development of effective therapy for superantigen-induced TSS. To fill these deficiencies, we systematically dissected the molecular pathogenesis of superantigen-induced TSS using the humanized human leukocyte antigen-DR3 transgenic mouse model by microarray-based gene expression profiling. Splenic expression of prostaglandin-endoperoxide synthase 2 (PTGS-2; also called cyclooxygenase 2 or COX-2) gene was increased by several hundred folds shortly after systemic superantigen (staphylococcal enterotoxin B [SEB]) exposure. In addition, expressions of several genes associated with eicosanoid pathway were significantly modulated by SEB, as analyzed by dedicated software. Given the importance of the COX-2 pathway in inflammation, we examined whether therapeutic inhibition of COX-2 by a highly selective inhibitor, CAY10404, could be beneficial. Our studies showed that i.p. administration of CAY10404 (50 mg/kg) immediately after challenge with 10 microg of SEB was unable to inhibit SEB-induced in vivo cytokine/chemokine production or T-cell activation/proliferation and did not prevent superantigen-associated thymocyte apoptosis.

Cyclo-oxygenase-2 and its inhibition in cancer: is there a role?

Despite recent improvements in chemotherapy and radiation therapy in cancer management with the addition of biological agents, novel treatment approaches are needed to further benefit patients. Cyclo-oxygenase (COX)-2 inhibition represents one such possibility. COX-2 is an enzyme induced in pathological states such as inflammatory disorders and cancer, where it mediates production of prostanoids. The enzyme is commonly expressed in both premalignant lesions and malignant tumours of different types. A growing body of evidence suggests an association of COX-2 with tumour development, aggressive biological tumour behaviour, resistance to standard cancer treatment, and adverse patient outcome. COX-2 may be related to cancer development and propagation through multiple mechanisms, including stimulation of growth, migration, invasiveness, resistance to apoptosis, suppression of the immunosurveillance system, and enhancement of angiogenesis. Epidemiological data suggest that NSAIDs and selective COX-2 inhibitors might prevent the development of cancers, including colorectal, oesophageal and lung cancer. Preclinical investigations have demonstrated that inhibition of this enzyme with selective COX-2 inhibitors enhances tumour response to radiation and chemotherapeutic agents. These preclinical findings have been rapidly advanced to clinical oncology. Clinical trials of the combination of selective COX-2 inhibitors with radiotherapy, chemotherapy or both in patients with a number of cancers have been initiated, and preliminary results are encouraging. This review discusses the role of COX-2, its products (prostaglandins) and its inhibitors in tumour growth and treatment.

Neuroprotective effect of protein kinase C delta inhibitor rottlerin in cell culture and animal models of Parkinson's disease

Recent studies from our laboratory demonstrated that the protein kinase C (PKC) delta isoform is an oxidative stress-sensitive kinase and a key mediator of apoptotic cell death in Parkinson's Disease (PD) models (Eur J Neurosci 18:1387-1401, 2003; Mol Cell Neurosci 25:406-421, 2004). We showed that native PKC delta is proteolytically activated by caspase-3 and that suppression of PKC delta by dominant-negative mutant or small interfering RNA against the kinase can effectively block apoptotic cell death in cellular models of PD. In an attempt to translate the mechanistic studies to a neuroprotective strategy targeting PKC delta, we systematically characterized the neuroprotective effect of a PKC delta inhibitor, rottlerin, in 1-methyl-4-phenylpyridinium (MPP(+))-treated primary mesencephalic neuronal cultures as well as in an 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) animal model of PD. Rottlerin treatment in primary mesencephalic cultures significantly attenuated MPP(+)-induced tyrosine hydroxylase (TH)-positive neuronal cell and neurite loss. Administration of rottlerin, either intraperitoneally or orally, to C57 black mice showed significant protection against MPTP-induced locomotor deficits and striatal depletion of dopamine and its metabolite 3,4-dihydroxyphenylacetic acid. Notably, rottlerin post-treatment was effective even when MPTP-induced depletion of dopamine and its metabolites was greater than 60%, demonstrating its neurorescue potential. Furthermore, the dose of rottlerin used in neuroprotective studies effectively attenuated the MPTP-induced PKC delta kinase activity. Importantly, stereological analysis of nigral neurons revealed rottlerin treatment significantly protected against MPTP-induced TH-positive neuronal loss in the substantia nigra compacta. Collectively, our findings demonstrate the neuroprotective effect of rottlerin in both cell culture and preclinical animal models of PD, and they suggest that pharmacological modulation of PKC delta may offer a novel therapeutic strategy for treatment of PD.

Dynamic simulations on the arachidonic acid metabolic network

Drug molecules not only interact with specific targets, but also alter the state and function of the associated biological network. How to design drugs and evaluate their functions at the systems level becomes a key issue in highly efficient and low-side-effect drug design. The arachidonic acid metabolic network is the network that produces inflammatory mediators, in which several enzymes, including cyclooxygenase-2 (COX-2), have been used as targets for anti-inflammatory drugs. However, neither the century-old nonsteriodal anti-inflammatory drugs nor the recently revocatory Vioxx have provided completely successful anti-inflammatory treatment. To gain more insights into the anti-inflammatory drug design, the authors have studied the dynamic properties of arachidonic acid (AA) metabolic network in human polymorphous leukocytes. Metabolic flux, exogenous AA effects, and drug efficacy have been analyzed using ordinary differential equations. The flux balance in the AA network was found to be important for efficient and safe drug design. When only the 5-lipoxygenase (5-LOX) inhibitor was used, the flux of the COX-2 pathway was increased significantly, showing that a single functional inhibitor cannot effectively control the production of inflammatory mediators. When both COX-2 and 5-LOX were blocked, the production of inflammatory mediators could be completely shut off. The authors have also investigated the differences between a dual-functional COX-2 and 5-LOX inhibitor and a mixture of these two types of inhibitors. Their work provides an example for the integration of systems biology and drug discovery.

Cyclooxygenase inhibitors modulate the p53/HDM2 pathway and enhance chemotherapy-induced apoptosis in neuroblastoma

Cyclooxygenase-2 (COX-2) is upregulated in many tumors including neuroblastoma, and its overexpression has been implicated in resistance to p53-dependent apoptosis. Although p53 is rarely mutated in neuroblastoma, the p53 protein is rendered inactive via several mechanisms including sequestration in the cytoplasm. Here, we show that COX inhibitors inhibit the growth of neuroblastoma and when combined with low doses of chemotherapy, exert synergistic effects on neuroblastoma cells. Following COX inhibitor treatment, HDM2, which targets p53 for ubiquitin-mediated degradation, is downregulated, resulting in an attenuation of p53 ubiquitination and an increase in p53 half-life. The level of HDM2 phosphorylation at ser166, which influences both HDM2 and p53 subcellular distribution, is markedly diminished in response to COX inhibitors and is associated with increased p53 nuclear localization. Combining COX inhibitors with low-dose chemotherapy potentiates apoptosis and p53 stability, nuclear localization, and activity. p53 knockdown by siRNA resulted in the rescue of COX-inhibitor-treated cells, indicating that COX inhibitor-induced apoptosis is, at least in part, p53-dependent. Taken together, these results provide the first evidence that COX inhibitors enhance chemosensitivity in neuroblastoma via downregulating HDM2 and augmenting p53 stability and nuclear accumulation.

Role of the Survivin gene in pathophysiology

Although the roles of survivin in control of cancer cell division and apoptosis as well as targeting survivin for cancer therapeutics have been extensively explored and reviewed, the pathophysiological role of survivin in normal human cells/organs has not been deeply investigated or sufficiently reviewed. Studies in the latter area, however, appear to be important for the identification of different mechanisms of regulation and function of survivin in normal versus abnormal cells and tissues (including cancer), which might ultimately provide the basis for novel approaches for disease treatment with low toxicity. This Review is intended to summarize current observations in the literature related to the physiological and/or pathological roles for survivin in various normal human cells or organs. Our view of potential future research directions for survivin pertinent to potential therapeutic applications will also be discussed.

Inhibition of human Neuroblastoma in SCID mice by low-dose of selective Cox-2 inhibitor Nimesulide

Neuroblastoma is the most common solid tumor of infants and carries a poor prognosis especially in advanced stages. The present recommended therapies carry a high risk of side effects that is associated with long-term morbidity. We evaluated the efficacy of a low dose of the selective cyclooxygenase-2 inhibitor Nimesulide in preventing human Neuroblastoma tumor growth in Severe Combined Immune-deficient mice. Mice containing established tumors (SH-SY5Y cells) treated with 20 mg/kg Nimesulide every 4th day beginning on day 1 of cell injections resulted in a 65% reduction of tumor growth compared to the DMSO treated control mice (P<0.05) but did not significantly reduce tumor growth when Nimesulide was started once tumors reached 1 cm. There was a reduction in the level of cyclooxygenase-2 protein and induction of effecter caspases in tumors treated with Nimesulide. However, there was no change in the levels of X-Inhibitor-of-Apoptosis-Protein, Smac/Diablo, or proteins of the PI3/Akt pathway following Nimesulide treatment. In Conclusion, low doses of Nimesulide can potentially be used as a chemopreventive agent for human Neuroblastoma.

Microglial phagocytosis induced by fibrillar beta-amyloid and IgGs are differentially regulated by proinflammatory cytokines

Microglia undergo a phenotypic activation in response to fibrillar beta-amyloid (fAbeta) deposition in the brains of Alzheimer's disease (AD) patients, resulting in their elaboration of inflammatory molecules. Despite the presence of abundant plaque-associated microglia in the brains of AD patients and in animal models of the disease, microglia fail to efficiently clear fAbeta deposits. However, they can be induced to do so during Abeta vaccination therapy attributable to anti-Abeta antibody stimulation of IgG receptor (FcR)-mediated phagocytic clearance of Abeta plaques. We report that proinflammatory cytokines attenuate microglial phagocytosis stimulated by fAbeta or complement receptor 3 and argue that this may, in part, underlie the accumulation of fAbeta-containing plaques within the AD brain. The proinflammatory suppression of fAbeta-elicited phagocytosis is dependent on nuclear factor kappaB activation. Significantly, the proinflammatory cytokines do not inhibit phagocytosis elicited by antibody-mediated activation of FcR, which may contribute to the efficiency of Abeta vaccination-based therapy. Importantly, the proinflammatory suppression of fAbeta phagocytosis can be relieved by the coincubation with anti-inflammatory cytokines, cyclooxygenase inhibitors, ibuprofen, or an E prostanoid receptor antagonist, suggesting that proinflammatory cytokines induce the production of prostaglandins, leading to an E prostanoid receptor-dependent inhibition of phagocytosis. These findings support anti-inflammatory therapies for the treatment of AD.

Nonsteroidal anti-inflammatory drugs inhibit the growth of C6 and U138-MG glioma cell lines

Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used drugs for the treatment of inflammatory disease and have a chemopreventive effect in a variety of tumors. Several studies have demonstrated unequivocally that certain NSAIDs cause antiproliferative effects independent of cyclooxygenase (COX) activity. In this study, we investigated the effect of chemically unrelated NSAIDs in the proliferation of glioma cell lines and the possible mechanisms involved in indomethacin-mediated inhibition of proliferation in glioma cells lines. The glioma cell lines were treated with NSAIDs and proliferation was measured by cell counting. Indomethacin, acetaminophen, sulindac sulfide and NS-398 (N-[2-cyclohexyloxy)-4-nitrophenyl]methane-sulfonamide) induced a time- and concentration-dependent inhibition of C6 rat glioma cell proliferation. The inhibition of COX by chemically unrelated NSAIDs leads to inhibition of rat and human glioma cell proliferation. The tetrazolium reduction assay (MTT) indicated a reduction in cell viability induced by indomethacin. None of the NSAIDs tested induced caspase-3/7 activation, assayed with a fluorigenic substrate. The indomethacin-induced inhibition of C6 cells proliferation was abrogated by the use of the c-Src inhibitor, PP2 and the MEK inhibitor, PD 098059, suggesting COX-independent mechanisms. Indomethacin decreased the percentage of cells in the S phase, with relative increases in the G0/G1 and/or the G2/M phase. NSAIDs may be clinically important for pharmacological intervention in gliomas.