Cyclooxygenase-2 modulates cellular growth and promotes tumorigenesis

Identification of Novel Kinase-Transcription Factor-mRNA-miRNA Regulatory Network in Nasopharyngeal Carcinoma by Bioinformatics Analysis

Purpose

Nasopharyngeal carcinoma (NPC) is one of the most common malignant tumors of the head and neck. This study aimed to investigate the crucial genes and regulatory networks involved in the carcinogenesis of NPC using a bioinformatics approach.

Methods

Five mRNA and two miRNA expression datasets were downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) and miRNAs (DEMs) between NPC and normal samples were analyzed using R software. The WebGestalt tool was used for functional enrichment analysis, and protein-protein interaction (PPI) network analysis of DEGs was performed using STRING database. Transcription factors (TFs) were predicted using TRRUST and Transcriptional Regulatory Element Database (TRED). Kinases were identified using X2Kgui. The miRNAs of DEGs were predicted using miRWalk database. A kinase-TF-mRNA-miRNA integrated network was constructed, and hub nodes were selected. The hub genes were validated using NPC datasets from the GEO and Oncomine databases. Finally, candidate small-molecule agents were predicted using CMap.

Results

A total of 122 DEGs and 44 DEMs were identified. DEGs were associated with the immune response, leukocyte activation, endoplasmic reticulum stress in GO analysis, and the NF-κB signaling pathway in KEGG analysis. Four significant modules were identified using PPI network analysis. Subsequently, 26 TFs, 73 kinases, and 2499 miRNAs were predicted. The predicted miRNAs were cross-referenced with DEMs, and seven overlapping miRNAs were selected. In the kinase-TF-mRNA-miRNA integrated network, eight genes (PTGS2, FN1, MMP1, PLAU, MMP3, CD19, BMP2, and PIGR) were identified as hub genes. Hub genes were validated with consistent results, indicating the reliability of our findings. Finally, six candidate small-molecule agents (phenoxybenzamine, luteolin, thioguanosine, reserpine, blebbistatin, and camptothecin) were predicted.

Conclusion

We identified DEGs and an NPC regulatory network involving kinases, TFs, mRNAs, and miRNAs, which might provide promising insight into the pathogenesis, treatment, and prognosis of NPC.

PDIA3 Expression in Glioblastoma Modulates Macrophage/Microglia Pro-Tumor Activation

The glioblastoma (GB) microenvironment includes cells of the innate immune system identified as glioma-associated microglia/macrophages (GAMs) that are still poorly characterized. A potential role on the mechanisms regulating GAM activity might be played by the endoplasmic reticulum protein ERp57/PDIA3 (protein disulfide-isomerase A3), the modulation of which has been reported in a variety of cancers. Moreover, by using The Cancer Genome Atlas database, we found that overexpression of PDIA3 correlated with about 55% reduction of overall survival of glioma patients. Therefore, we analyzed the expression of ERp57/PDIA3 using specimens obtained after surgery from 18 GB patients. Immunohistochemical analysis of tumor samples revealed ERp57/PDIA3 expression in GB cells as well as in GAMs. The ERp57/PDIA3 levels were higher in GAMs than in the microglia present in the surrounding parenchyma. Therefore, we studied the role of PDIA3 modulation in microglia-glioma interaction, based on the ability of conditioned media collected from human GB cells to induce the activation of microglial cells. The results indicated that reduced PDIA3 expression/activity in GB cells significantly limited the microglia pro-tumor polarization towards the M2 phenotype and the production of pro-inflammatory factors. Our data support a role of PDIA3 expression in GB-mediated protumor activation of microglia.

Pyruvate Kinase M2 Promotes Prostate Cancer Metastasis Through Regulating ERK1/2-COX-2 Signaling

Pyruvate kinase M2 (PKM2) is a key enzyme of glycolysis, which is highly expressed in many tumor cells, and has emerged as an important player in tumor progression and metastasis. However, the functional roles of PKM2 in tumor metastasis remain elusive. Here we showed that PKM2 promoted prostate cancer metastasis via extracellular-regulated protein kinase (ERK)-cyclooxygenase (COX-2) signaling. Based on public databases, we found that PKM2 expression was upregulated in prostate cancer and positively associated with tumor metastasis. Further analysis showed that PKM2 promoted prostate cancer cell migration/invasion and epithelial-mesenchymal transition (EMT) through upregulation of COX-2. Mechanistically, PKM2 interacted with ERK1/2 and regulated its phosphorylation, leading to phosphorylation of transcription factor c-Jun, downstream of ERK1/2, to activate COX-2 transcription by IP and ChIP assay, while inhibition of COX-2 significantly reversed the promotion effect of PKM2 on tumor metastasis in vivo. Taken together, our results suggest that a novel of PKM2-ERK1/2-c-Jun-COX-2 axis is a potential target in controlling prostate cancer metastasis.

Single Nucleotide Variants Associated with Colorectal Cancer Among Iranian Patients: A Narrative Review

Colorectal cancer has been considered as one of the complicated multi-stage processes after adenoma-carcinoma sequence. Therefore, studies of the molecular dysregulation basis could present information on the recognition of the potent biomarkers and treatment targets for this disease. Even though outcomes of the patients with colorectal cancer have been improved largely with current annual screening plans, it is necessary to have reliable prognostic biomarkers because of the disease heterogeneity. There is a significant relationship between SNP in IL1RN* 2 (IL1ra), −509 C/T (TGFB1), rs11556218 T>G and rs4778889 T/C (IL16), miRNA-binding site polymorphisms in IL16, rs4464148 (SMAD7), rs6983267 (EGF), GSTT1, TACG haplotype (CTLA4), 1793G> A (MTHFR), Leu/Leu genotype of (EXO1), −137 G/C (IL18), C/T genotype (XRCC3), I3434T (XRCC7), MGMT, C3435T (MDR1), ff genotype of FokI, 677CT+TT (MTHFR), G2677T/A (MDR1) and CRC. Increased risk has been observed in VDR ApaI genotype “aa”. Finally, the protective effect has been explored in the TACA haplotype (CTLA4). According to the findings, the genetic polymorphisms in the immunity-associated genes are related to the CRC amongst the Iranian patients. Therefore, more large-scale functional investigations are necessary for confirming the results.

Suppression of the solar ultraviolet-induced skin carcinogenesis by TOPK inhibitor HI-TOPK-032

Nonmelanoma skin cancer (NMSC) such as cutaneous squamous cell carcinoma (cSCC) is caused by solar ultraviolet (SUV) exposure and is the most common cancer in the United States. T-LAK cell-originated protein kinase (TOPK), a serine-threonine kinase is activated by SUV irradiation and involved in skin carcinogenesis. Strategies with research focusing on the TOPK signaling pathway and targeted therapy in skin carcinogenesis may helpful for the discovery of additional treatments against skin cancer. In this study, we found that TOPK can directly bind to and phosphorylate c-Jun (as one of the core member of AP-1) at Ser63 and Ser73 after SSL exposure in a JNKs-independent manner. TOPK knocking down, or HI-TOPK-032 (TOPK specific inhibitor) attenuated colony formation and cell proliferation of skin cancer cells. Phosphorylated levels of c-Jun were overexpressed in human AK and cSCC compared with normal skin tissues, and HI-TOPK-032 inhibited the phosphorylation of c-Jun in SCC cell line in a dose-dependent manner. Furthermore, HI-TOPK-032 decreased SSL-induced AP-1 transactivation activity. Moreover, acute SSL-induced inflammation was attenuated by the topical application of HI-TOPK-032 in SKH1 hairless mice. Importantly, HI-TOPK-032 suppressed chronic SSL-induced skin carcinogenesis and c-Jun phosphorylation levels in SKH1 hairless mice. Our results demonstrate that TOPK can phosphorylate and activate c-Jun at Ser63 and Ser73 in the process of skin carcinogenesis and HI-TOPK-032 could be used as a potential chemopreventive drug against cSCC development.

Transition Metal-Based Prodrugs for Anticancer Drug Delivery

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Transition metal complexes, of which the platinum(II) complex cisplatin is an example, have been used in medicine to treat cancer for more than 40 years. Although many successes have been achieved, there are problems associated with the use of these drugs, such as side effects and drug resistance. Converting them into prodrugs, to make them more inert, so that they can travel to the tumour site unchanged and release the drug in its active form only there, is a strategy which is the subject of much research nowadays. The new prodrugs may be activated and release the cytotoxic agent by differences in oxygen concentration or in pH, by the action of overexpressed enzymes, by differences in metabolic rates, etc., which characteristically distinguish cancer cells from normal ones, or even by the input of radiation, which can be visible light. Converting a metal complex into a prodrug may also be used to improve its pharmacological properties. In some cases, the metal complex is a carrier which transports the active drug as a ligand. Some platinum prodrugs have reached clinical trials. So far platinum, ruthenium and cobalt have been the most studied metals. This review presents the recent developments in this area, including the types of complexes used, the mechanisms of drug action and in some cases the techniques applied to monitor drug delivery to cells.

Association of Cyclooxygenase-2 Immunoreactivity with Tumor Recurrence and Disease Progression in Superficial Urothelial Bladder Cancer

Aims and Background

The main characteristic of urothelial bladder cancer is a clear predisposition to recurrence and disease progression. The aim of this study was to assess the possible relationship between cyclooxygenase-2 (COX-2) immunoreactivity in superficial urothelial bladder carcinoma and tumor grade, stage, number of recurrences and clinical disease progression.

Methods

In this prospective study 70 consecutive patients who underwent transurethral resection for superficial urothelial bladder cancer were included. Tumor slides were immuno-histochemically stained for COX-2, and COX-2 immunoreactivity in tumor and inflammatory stromal cells was categorized as negative or mildly, moderately or strongly positive. Patients were followed up for 2 years, and during this period the possible association of COX-2 immunoreactivity with tumor stage and grade, number of recurrences and progression of disease was evaluated.

Results

COX-2 immunoreactivity in tumor cells was found in 57 (81.4%) patients and did not correlate with tumor grade, stage of disease, number of recurrences, and progression of disease. COX-2 immunoreactivity in inflammatory cells was found in 16 of the 57 patients with COX-2 positive tumors, and was significantly related to the number of recurrences, time to appearance of the first recurrence, and disease progression.

Conclusions

COX-2 immunoreactivity in inflammatory stromal cells adjacent to the COX-2-positive tumor might be useful in clinical practice for selection of patients with a high risk of tumor recurrence and disease progression.

Anti-metastatic Properties of Naproxen-HBTA in a Murine Model of Cutaneous Melanoma

The beneficial effects of H₂S-release and of COXs-inhibition have been exploited in the design of novel anti-inflammatory drugs, the H₂S-releasing non-steroidal anti-inflammatory drugs (H₂S-NSAIDs), showing promising potential for chemoprevention in cancers. Here, we evaluated the efficacy of a new H₂S-releasing derivative of naproxen, named naproxen-4-hydroxybenzodithioate (naproxen-HBTA), in reducing metastatic melanoma features, both in vitro and in vivo. The novel H₂S donor has been prepared following a synthetic scheme that provided high yields and purity. In particular, we investigated the effect of naproxen-HBTA in vitro on several metastatic features of human melanoma cells such as proliferation, migration, invasion, and colonies formation and in vivo in a model of cutaneous melanoma. Cell culture studies demonstrated that naproxen-HBTA induced caspase 3-mediated apoptosis and inhibited motility, invasiveness, and focus formation. Finally, daily oral treatment with naproxen-HBTA significantly suppressed melanoma growth and progression in mice. In conclusion, by using this dual approach we propose that the COX-2 and H₂S pathways could be regarded as novel therapeutic targets/tools to generate new treatment options based on "combination therapy" for melanoma.

Association between cyclooxygenase-2 (COX-2) 8473 T > C polymorphism and cancer risk: a meta-analysis and trial sequential analysis

Background

Numerous studies have investigated the relationship between COX-2 8473 T > C polymorphism and cancer susceptibility, however, the results remain controversial. Therefore, we carried out the present meta-analysis to obtain a more accurate assessment of this potential association.

Methods

In this meta-analysis, 79 case-control studies were included with a total of 38,634 cases and 55,206 controls. We searched all relevant articles published in PubMed, EMBASE, OVID, Web of Science, CNKI and Wanfang Data, till September 29, 2017. The pooled odds ratios (ORs) with 95% confidence intervals (CIs) were used to evaluate the strength of the association. We performed subgroup analysis according to ethnicity, source of controls, genotyping method and cancer type. Moreover, Trial sequential analysis (TSA) was implemented to decrease the risk of type I error and estimate whether the current evidence of the results was sufficient and conclusive.

Results

Overall, our results indicated that 8473 T > C polymorphism was not associated with cancer susceptibility. However, stratified analysis showed that the polymorphism was associated with a statistically significant decreased risk for nasopharyngeal cancer and bladder cancer, but an increased risk for esophageal cancer and skin cancer. Interestingly, TSA demonstrated that the evidence of the result was sufficient in this study.

Conclusion

No significant association between COX-2 8473 T > C polymorphism and cancer risk was detected.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4753-3) contains supplementary material, which is available to authorized users.

Antitumor Perspectives of Oleuropein and Its Metabolite Hydroxytyrosol: Recent Updates

Olive fruit is a significant and promising source of potential bioactive compounds such as oleuropein and hydroxytyrosol. Oleuropein is the ester of elenolic acid and 3,4-dihydroxyphenyl ethanol (HT). It is the main glycoside in olives, the degradation of which results in the formation of hydroxytyrosol in olive oil. Both plays a significant role in the reduction of coronary heart diseases and a certain type of cancers. Both olive oil phenols have an effective role counter to cell proliferation, cell growth, migration, invasion, and angiogenesis. They down regulate the expression of BCL-2 and COX-2 proteins, and reduced DNA damage. Hydroxytyrosol and oleuropein inhibited the multiple stages in colon carcinogenesis; initiation, promotion, and metastasis. They also provide protection against various human cancers including colorectal, skin, breast, thyroid, digestive, lung, brain, blood, and cervical. This review article discusses the anticancer perspectives and mechanisms of oleuropein and hydroxytyrosol in cell cultures and animal and human studies.

Targeting PRPK and TOPK for skin cancer prevention and therapy

Solar ultraviolet (sUV) irradiation is a major environmental carcinogen that can cause inflammation and skin cancer. The costs and morbidity associated with skin cancer are increasing, and therefore identifying molecules that can help prevent skin carcinogenesis is important. In this study, we identified the p53-related protein kinase (PRPK) as a novel oncogenic protein that is phosphorylated by the T-LAK cell-originated protein kinase (TOPK). Knockdown of TOPK inhibited PRPK phosphorylation and conferred resistance to solar-simulated light (SSL)-induced skin carcinogenesis in mouse models. In the clinic, acute SSL irradiation significantly increased epidermal thickness as well as total protein and phosphorylation levels of TOPK and PRPK in human skin tissues. We identified two PRPK inhibitors, FDA-approved rocuronium bromide (Zemuron^®) or betamethasone 17-valerate (Betaderm^®) that could attenuate TOPK-dependent PRPK signaling. Importantly, topical application of either rocuronium bromide or betamethasone decreased SSL-induced epidermal hyperplasia, neovascularization, and cutaneous squamous cell carcinoma (cSCC) development in SKH1 (Crl: SKH1-Hr^hr) hairless mice by inhibiting PRPK activation, and also reduced expression of the proliferation and oncogenesis markers, COX-2, cyclin D1, and MMP-9. This study is the first to demonstrate that targeting PRPK could be useful against sUV-induced cSCC development.

Evaluation of the anti-inflammatory activity of Tinospora cordifolia (Willd.) Miers chloroform extract – a preclinical study

Objectives

Tinospora cordifolia (Willd.) Miers is an inevitable ingredient of Ayurvedic rasayanas for the treatment of disorders with unregulated inflammation. However, studies regarding the mechanism of anti-inflammatory potential of this plant at the molecular level are lacking.

Methods

In vitro evaluations were conducted in RAW264.7 macrophages which were preincubated with chloroform extract of T. cordifolia (CETC) and subsequently stimulated with LPS. The expressions of COX-2, TNF-α and iNOS genes were analysed by SQRT-PCR and Western blot, cytokines (IL-6, IL-1β and PGE2) levels by ELISA, NF-κB activation and p38 MAPK phosphorylation by Immunoblot and confocal imaging. Anti-inflammatory potential of CETC was validated further in a rat model of carrageenan-induced hind paw edema. Phytochemical characterisation was carried out using the HPLC technique.

Key findings

The LPS-induced upregulation of proinflammatory biomarkers was significantly prevented by CETC, without inhibiting COX-1. CETC- and LPS-incubated cells showed reduced phosphorylated p38 MAPK levels, and higher levels NF-κB were retained in cytoplasm. Rats pretreated with CETC showed a statistically significant decrease in paw oedema (P ≤ 0.05), and HPLC characterisation detected stigmasterol and β-sitosterol. The LD50 of CETC lies above 2000 mg/Kg body weight.

Conclusions

These findings encourage us strongly to focus on CETC to develop anti-inflammatory drugs with lower degree of inhibition to the constitutively expressing COX-1.

Expression and clinical significance of cyclooxygenase 2 and survivin in human gliomas

The present study aimed to determine cyclooxygenase 2 (COX-2) and survivin expression levels in glioma tissues, and to investigate their association with clinicopathological factors and patient survival. Immunohistochemistry was performed to evaluate COX-2 and survivin expression levels in paraffin-embedded surgically resected tissues from 70 patients with glioma and 7 individuals with normal brain tissues. The association between COX-2 and survivin expression levels and clinicopathological features was investigated using the χ² test, and the survival time was analyzed using the Kaplan Meier method with log-rank test. COX-2 and survivin were overexpressed in glioma tissues, and higher expression levels were observed in glioma tissues of histological grades III–IV compared with those in grade I–II tumor tissues (P<0.05); however, the expression levels were not associated with gender, age, tumor size or location (P>0.05). There was a significant positive association between the expression levels of COX-2 and survivin in the glioma tissues. Additionally, COX-2 and survivin expression levels were significantly negatively correlated with the rate of survival. In conclusion, COX-2 and survivin expression is positively associated with the pathological grade of a glioma and may contribute to glioma tumorigenesis. Therefore, COX-2 and survivin may be sensitive predictors of a negative clinical prognosis for patients with glioma.

Consumption of Red/Processed Meat and Colorectal Carcinoma: Possible Mechanisms Underlying the Significant Association

Epidemiology and experimental studies provide an overwhelming support of the notion that diets high in red or processed meat accompany an elevated risk of developing pre-neoplastic colorectal adenoma and frank colorectal carcinoma (CRC). The underlying mechanisms are disputed; thus several hypotheses have been proposed. A large body of reports converges, however, on haem and nitrosyl haem as major contributors to the CRC development, presumably acting through various mechanisms. Apart from a potentially higher intestinal mutagenic load among consumers on a diet rich in red/processed meat, other mechanisms involving subtle interference with colorectal stem/progenitor cell survival or maturation are likewise at play. From an overarching perspective, suggested candidate mechanisms for red/processed meat-induced CRC appear as three partly overlapping tenets: (i) increased N-nitrosation/oxidative load leading to DNA adducts and lipid peroxidation in the intestinal epithelium, (ii) proliferative stimulation of the epithelium through haem or food-derived metabolites that either act directly or subsequent to conversion, and (iii) higher inflammatory response, which may trigger a wide cascade of pro-malignant processes. In this review, we summarize and discuss major findings of the area in the context of potentially pertinent mechanisms underlying the above-mentioned association between consumption of red/processed meat and increased risk of developing CRC.

Resistance to ursolic acid-induced apoptosis through involvement of melanogenesis and COX-2/PGE2 pathways in human M4Beu melanoma cancer cells

Melanoma is one of the most aggressive forms of cancer with a continuously growing incidence worldwide and is usually resistant to chemotherapy agents, which is due in part to a strong resistance to apoptosis. Previously, we had showed that B16-F0 murine melanoma cells undergoing apoptosis are able to delay their own death induced by ursolic acid (UA), a natural pentacyclic triterpenoid compound. We had demonstrated that tyrosinase and TRP-1 up-regulation in apoptotic cells and the subsequent production of melanin were implicated in an apoptosis resistance mechanism. Several resistance mechanisms to apoptosis have been characterized in melanoma such as hyperactivation of DNA repair mechanisms, drug efflux systems, and reinforcement of survival signals (PI3K/Akt, NF-κB and Raf/MAPK pathways). Otherwise, other mechanisms of apoptosis resistance involving different proteins, such as cyclooxygenase-2 (COX-2), have been described in many cancer types. By using a strategy of specific inhibition of each ways, we suggested that there was an interaction between melanogenesis and COX-2/PGE2 pathway. This was characterized by analyzing the COX-2 expression and activity, the expression of tyrosinase and melanin production. Furthermore, we showed that anti-proliferative and proapoptotic effects of UA were mediated through modulation of multiple signaling pathways including Akt and ERK-1/2 proteins. Our study not only uncovers underlying molecular mechanisms of UA action in human melanoma cancer cells but also suggest its great potential as an adjuvant in treatment and cancer prevention.

Immunohistochemical expression of cyclooxygenase-2 (COX-2) in oral nevi and melanoma

BACKGROUND

Cyclooxygenase-2 (COX-2) catalyses the conversion of arachidonic acid to prostaglandin, and its overexpression has been demonstrated in different malignant tumors, including cutaneous melanoma. However, no data about the expression of this protein in oral melanocytic lesions are available to date. The aim of this study was to evaluate the immunohistochemical expression of COX-2 in oral nevi and melanomas, comparing the results with correspondent cutaneous lesions.

METHODS

COX-2 was evaluated by immunohistochemistry in 49 oral melanocytic lesions, including 36 intramucosal nevi and 13 primary oral melanomas, and in four cutaneous nevi and eight melanomas.

RESULTS

All cases of oral and cutaneous melanomas were positive for COX-2. On the other hand, all oral and cutaneous melanocytic nevi were negative.

CONCLUSION

COX-2 is highly positive in oral melanomas and negative in oral nevi and might represent a useful marker to distinguish melanocytic lesions of the oral cavity.

The Next Generation of Platinum Drugs: Targeted Pt(II) Agents, Nanoparticle Delivery, and Pt(IV) Prodrugs

The platinum drugs, cisplatin, carboplatin, and oxaliplatin, prevail in the treatment of cancer, but new platinum agents have been very slow to enter the clinic. Recently, however, there has been a surge of activity, based on a great deal of mechanistic information, aimed at developing nonclassical platinum complexes that operate via mechanisms of action distinct from those of the approved drugs. The use of nanodelivery devices has also grown, and many different strategies have been explored to incorporate platinum warheads into nanomedicine constructs. In this Review, we discuss these efforts to create the next generation of platinum anticancer drugs. The introduction provides the reader with a brief overview of the use, development, and mechanism of action of the approved platinum drugs to provide the context in which more recent research has flourished. We then describe approaches that explore nonclassical platinum(II) complexes with trans geometry or with a monofunctional coordination mode, polynuclear platinum(II) compounds, platinum(IV) prodrugs, dual-threat agents, and photoactivatable platinum(IV) complexes. Nanoparticles designed to deliver platinum(IV) complexes will also be discussed, including carbon nanotubes, carbon nanoparticles, gold nanoparticles, quantum dots, upconversion nanoparticles, and polymeric micelles. Additional nanoformulations, including supramolecular self-assembled structures, proteins, peptides, metal-organic frameworks, and coordination polymers, will then be described. Finally, the significant clinical progress made by nanoparticle formulations of platinum(II) agents will be reviewed. We anticipate that such a synthesis of disparate research efforts will not only help to generate new drug development ideas and strategies, but also will reflect our optimism that the next generation of approved platinum cancer drugs is about to arrive.

Dual effects of acetylsalicylic acid on ERK signaling and Mitf transcription lead to inhibition of melanogenesis

Acetylsalicylic acid (ASA) is widely used as an analgesic/antipyretic drug. It exhibits a wide range of biological effects, including preventative effects against heart attack and stroke, and the induction of apoptosis in various cancer cells. We previously found that ASA inhibits melanogenesis in B16 melanoma cells. However, the mechanisms of how ASA down-regulates melanin synthesis remain unclear. Here, we investigated the effect of ASA on melanogenic pathways, such as extracellular signal-regulated kinase (ERK) and microphthalmia-associated transcription factor (Mitf) transcription. ASA significantly inhibited melanin synthesis in a dose-dependent manner without oxidative stress and cell death. Semi-quantitative reverse transcription-polymerase chain reaction analysis showed that the inhibitory effect of ASA might be due to the inhibition of Mitf gene transcription. Interestingly, ASA also induced ERK phosphorylation. Additionally, treatment with PD98059, a specific ERK phosphorylation inhibitor, abolished the anti-melanogenic effect of ASA. These results suggest that the depigmenting effect of ASA results from down-regulation of Mitf, which is induced by both the induction of ERK phosphorylation and the inhibition of Mitf transcription.

Association between COX-2 gene polymorphisms and risk of hepatocellular carcinoma development: a meta-analysis

OBJECTIVE

To investigate the association between cyclo-oxygenase-2 (COX-2) polymorphism and the risk of hepatocellular carcinoma (HCC) development.

DESIGN

Systematic review and meta-analysis of COX-2 polymorphism and risk of HCC development among people with or without HCC.

DATA SOURCES

EMBASE, PubMed, Public Library of Science, SCOPUS, Web of Knowledge and Chinese National Knowledge Infrastructure were searched for all clinical and experimental case-control studies of COX-2 polymorphism and HCC risk. Studies published up to March 2015 were included.

REVIEW METHOD

Ten studies were included for data extraction, which were mainly from Asian countries.

RESULTS

2538 people with HCC and 3714 without HCC were found to satisfy the inclusion criteria and included in the review. The associations of specific genotypes in the eight polymorphic variants of COX-2 and the risk of HCC development were analysed. GG genotype at the A-1195G polymorphism may be associated with a reduced risk of HCC development: the OR across all studies was 0.87 (95% CI 0.75 to 1.02) for the G allele versus the A allele, 0.72 (0.53 to 0.97) for GG versus AA, 0.72 (0.57 to 0.92) for GG versus GA+AA and 1.05 (0.77 to 1.44) for AA versus GA+GG. Similar results were found when the meta-analysis was repeated separately for the Chinese subgroup. However, more reliable data are needed to demonstrate associations between variants in G-765C, T+8473C, A-1290G, G-899C and introns 1, 5 and 6 polymorphisms and the risk of HCC development.

CONCLUSIONS

Only the COX-2 A-1195G gene polymorphism may be associated with a decreased risk of HCC development. These conclusions should be verified in further studies.

Chemotherapeutic potential of diazeniumdiolate-based aspirin prodrugs in breast cancer

Diazeniumdiolate-based aspirin prodrugs have previously been shown to retain the anti-inflammatory properties of aspirin while protecting against the common side effect of stomach ulceration. Initial analysis of two new prodrugs of aspirin that also release either nitroxyl (HNO) or nitric oxide (NO) demonstrated increased cytotoxicity toward human lung carcinoma cells compared to either aspirin or the parent nitrogen oxide donor. In addition, cytotoxicity was significantly lower in endothelial cells, suggesting cancer-specific sensitivity. To assess the chemotherapeutic potential of these new prodrugs in treatment of breast cancer, we studied their effect both in cultured cells and in a nude mouse model. Both prodrugs reduced growth of breast adenocarcinoma cells more effectively than the parent compounds while not being appreciably cytotoxic in a related nontumorigenic cell line (MCF-10A). The HNO donor also was more cytotoxic than the related NO donor. The basis for the observed specificity was investigated in terms of impact on metabolism, DNA damage and repair, apoptosis, angiogenesis and metastasis. The results suggest a significant pharmacological potential for treatment of breast cancer.

Diacetyloxyl derivatization of the fibroblast growth factor inhibitor dobesilate enhances its anti-inflammatory, anti-angiogenic and anti-tumoral activities

BACKGROUND

Dobesilate (2,5-dihydroxyphenyl sulfonate, DHPS) was recently identified as the most potent member of a family of fibroblast growth factor (FGF) inhibitors headed by gentisic acid, one of the main catabolites of aspirin. Although FGFs were first described as inducers of angiogenesis, they were soon recognized as broad spectrum mitogens. Furthermore, in the last decade these proteins have been shown to participate directly in the onset of inflammation, and their potential angiogenic activity often contributes to the inflammatory process in vivo. The aim of this work was to evaluate the anti-inflammatory, anti-angiogenic and anti-tumoral activities of the derivative of DHPS obtained by acetoxylation of its two hydroxyl groups (2,5-diacetoxyphenyl sulfonate; DAPS).

METHODS

Anti-inflammatory, anti-angiogenic and anti-tumoral activities of DHPS and DAPS were compared using in vivo assays of dermatitis, angiogenesis and tumorigenesis. The effects of both compounds on myeloperoxidase (MPO) and cyclooxygenase (COX) activities, cytokine production and FGF-induced fibroblast proliferation were also determined.

RESULTS

Topical DAPS is more effective than DHPS in preventing inflammatory signs (increased vascular permeability, edema, leukocyte infiltration, MPO activation) caused by contact dermatitis induction in rat ears. DAPS, but not DHPS, effectively inhibits COX-1 and COX-2 activities. DAPS also reduces the increase in serum cytokine concentration induced by lipopolysaccharide in rats. Furthermore, DAPS displays higher in vivo efficacy than DHPS in inhibiting FGF-induced angiogenesis and heterotopic glioma progression, with demonstrated oral efficacy to combat both processes.

CONCLUSIONS

By inhibiting both FGF-signaling and COX-mediated prostaglandin synthesis, DAPS efficiently breaks the vicious circle created by the reciprocal induction of FGF and prostaglandins, which probably sustains undesirable inflammation in many circumstances. Our findings define the enhancement of anti-inflammatory, anti-angiogenic and anti-tumoral activities by diacetyloxyl derivatization of the FGF inhibitor, dobesilate.

Stromal, rather than epithelial cyclooxygenase-2 (COX-2) expression is associated with overall survival of breast cancer patients

Background

Prognostic value of enhanced COX-2 expression in breast cancer has been controversial for a long time. The opinions vary widely between studies. Moreover, significant majority of studies considered only COX-2 expression in cancer epithelial cells.

Methods

We examined the prognostic value of COX-2 expression in both epithelial and stromal cells using three different antibodies and three algorithms of immunohistochemical scoring and categorizing the tumours into COX-2 overexpressing groups.

Results

Our results demonstrate that COX-2 expression in stromal cells is independent prognostic factor indicating worse overall survival of patients. Such a result was obtained using each of the three antibodies and two of the algorithms used for evaluations of COX-2 expression levels. We also show that immunohistochemical assessment of the prognostic value of COX-2 expression in cancer epithelial cells depends to a large extent on a combination of primary antibodies and algorithms used for determination of the COX-2 over-expressing tumours.

Conclusions

Our results indicate that stromal expression of COX-2 is independent prognostic parameter relatively insensitive to variations in sensitivity of antibodies used for its determination. Wide scatter of the published results concerning prognostic value of COX-2 expression in breast cancer tissues seems to be due to a large extent to multitude of antibodies and scoring algorithms used by different groups.

Transcription factor Ets-1 inhibits glucose-stimulated insulin secretion of pancreatic β-cells partly through up-regulation of COX-2 gene expression

Increased cyclooxygenase-2 (COX-2) expression is associated with pancreatic β-cell dysfunction. We previously demonstrated that the transcription factor Ets-1 significantly up-regulated COX-2 gene promoter activity. In this report, we used the pancreatic β-cell line INS-1 and isolated rat islets to investigate whether Ets-1 could induce β-cell dysfunction through up-regulating COX-2 gene expression. We investigated the effects of ETS-1 overexpression and the effects of ETS-1 RNA interference on endogenous COX-2 expression in INS-1 cells. We used site-directed mutagenesis and a dual luciferase reporter assay to study putative Ets-1 binding sites in the COX-2 promoter. The effect of ETS-1 1 overexpression on the insulin secretion function of INS-1 cells and rat islets and the potential reversal of these effects by a COX-2 inhibitor were determined in a glucose-stimulated insulin secretion (GSIS) assay. ETS-1 overexpression significantly induces endogenous COX-2 expression, but ETS-1 RNA interference has no effect on basal COX-2 expression in INS-1 cells. Ets-1 protein significantly increases COX-2 promoter activity through the binding site located in the -195/-186 region of the COX-2 promoter. ETS-1 overexpression significantly inhibited the GSIS function of INS-1 cells and islet cells and COX-2 inhibitor treatment partly reversed this effect. These findings indicated that ETS-1 overexpression induces β-cell dysfunction partly through up-regulation of COX-2 gene expression. Moreover, Ets-1, the transcriptional regulator of COX-2 expression, may be a potential target for the prevention of β-cell dysfunction mediated by COX-2.

Src is activated by the nuclear receptor peroxisome proliferator-activated receptor β/δ in ultraviolet radiation-induced skin cancer

Although non-melanoma skin cancer (NMSC) is the most common human cancer and its incidence continues to rise worldwide, the mechanisms underlying its development remain incompletely understood. Here, we unveil a cascade of events involving peroxisome proliferator-activated receptor (PPAR) β/δ and the oncogene Src, which promotes the development of ultraviolet (UV)-induced skin cancer in mice. UV-induced PPARβ/δ activity, which directly stimulated Src expression, increased Src kinase activity and enhanced the EGFR/Erk1/2 signalling pathway, resulting in increased epithelial-to-mesenchymal transition (EMT) marker expression. Consistent with these observations, PPARβ/δ-null mice developed fewer and smaller skin tumours, and a PPARβ/δ antagonist prevented UV-dependent Src stimulation. Furthermore, the expression of PPARβ/δ positively correlated with the expression of SRC and EMT markers in human skin squamous cell carcinoma (SCC), and critically, linear models applied to several human epithelial cancers revealed an interaction between PPARβ/δ and SRC and TGFβ1 transcriptional levels. Taken together, these observations motivate the future evaluation of PPARβ/δ modulators to attenuate the development of several epithelial cancers.

Formulation and optimization of celecoxib-loaded PLGA nanoparticles by the Taguchi design and their in vitro cytotoxicity for lung cancer therapy

The objective of the present study was to develop, evaluate and optimize a polymeric nanoparticle (NP) system containing Cxb for pulmonary delivery of Cxb in the treatment of lung cancer. NPs were prepared by the emulsion solvent diffusion and evaporation method using poly(D, L lactideglycolide) (PLGA). The size of NPs ranged from 153 to 192 nm and was affected by PLGA content, surfactant concentration and organic phase volume. Zeta potential of NPs (-4.5 to -8.6 mV) was more affected by PLGA content and organic phase volume. PLGA content was also the most effective factor on the entrapment efficiency and release rate of Cxb from NPs. The optimum formulation which obtained with 5 mg Cxb, 25 mg PLGA, 0.5% surfactant, 2.5% organic volume and 15 000 rpm showed release of Cxb within 30 h. The optimized formulation co-spray dried with lactose (hybrid microparticles) displayed desirable fine particle fraction, mass medium aerodynamic diameter, geometric standard deviation of 70.3%, 1.46% and 3.38%, respectively. Our results provide evidence for the potential of PLGA NPs for delivery of Cxb through inhalation as means to alleviate the cardiovascular risk of Cxb administration.

COX-2 polymorphisms -765G→C and -1195A→G and hepatocellular carcinoma risk

Cyclooxygenase-2 (COX-2) is overexpressed in hepatocellular carcinoma (HCC) and considered to play a role in hepatic carcinogenesis. Our aim was to examine the associations between polymorphisms in COX-2 -765G→C and -1195A→G and risk of HCC. We conducted a case-control study including 120 patients with HCC and 130 age- and gender-matched controls. Genotypes of the COX-2 polymorphisms -765G→C and -1195A→G were determined by polymerase chain reaction-based restriction fragment length polymorphism. No significant difference was observed in the genotype distribution of the -765G→C polymorphism between patients and controls. The -1195AA genotype was associated with an increased risk of developing HCC (OR, 2.5; 95%CI, 1.18-5.37). The A allele was present significantly more often in HCC patients (OR 1.5; 95%CI, 1.05-2.14). In conclusion, our results demonstrated that the -1195AA genotype and A allele have an important role in HCC risk in Egyptian patients.

COX-2 overexpression increases malignant potential of human glioma cells through Id1

Increased COX-2 expression directly correlates with glioma grade and is associated with shorter survival in glioblastoma (GBM) patients. COX-2 is also regulated by epidermal growth factor receptor signaling which is important in the pathogenesis of GBMs. However, COX-2 expression has not been previously shown to directly alter malignancy of GBMs. Id1 is a member of the helix-loop-helix (HLH) family of transcriptional repressors that act as dominant-negative inhibitors of basic-HLH factors. This factor has been shown to be regulated by COX-2 in breast carcinoma cells and recent studies suggest that Id1 may also be involved in the genesis/progression of gliomas. We now show that COX-2 increases the aggressiveness of GBM cells. GBM cells with COX-2 overexpression show increased growth of colonies in soft agar. Tumorigenesis in vivo is also increased in both subcutaneous flank and orthotopic intracranial tumor models. COX-2 overexpression induces Id1 expression in two GBM cell lines suggesting a role for Id1 in glioma transformation/tumorigenesis. Furthermore, we find direct evidence of a role for Id1 with significant suppression of in vitro transformation and in vivo tumorigenesis in COX-2-overexpressing GBM cells where Id1 has been knocked down. In fact, Id1 is even more efficient at enhancing transformation/tumorigenesis of GBM cells than COX-2. Finally, GBM cells with COX-2 or Id1 overexpression show greater migration/invasive potential and tumors that arise from these cells also display increased microvessel density, results in line with the increased malignant potential seen in these cells. Thus, COX-2 enhances the malignancy of GBM cells through induction of Id1.

Molecular mechanisms of mouse skin tumor promotion

Multiple molecular mechanisms are involved in the promotion of skin carcinogenesis. Induction of sustained proliferation and epidermal hyperplasia by direct activation of mitotic signaling pathways or indirectly in response to chronic wounding and/or inflammation, or due to a block in terminal differentiation or resistance to apoptosis is necessary to allow clonal expansion of initiated cells with DNA mutations to form skin tumors. The mitotic pathways include activation of epidermal growth factor receptor and Ras/Raf/mitogen-activated protein kinase signaling. Chronic inflammation results in inflammatory cell secretion of growth factors and cytokines such as tumor necrosis factor-α and interleukins, as well as production of reactive oxygen species, all of which can stimulate proliferation. Persistent activation of these pathways leads to tumor promotion.

Cyclooxygenase-2 polymorphisms and susceptibility to colorectal cancer: a meta-analysis

PURPOSE

Four polymorphisms, -765G>C, -1195G>A, 8473T>C, and Val511Ala, in the cyclooxygenase-2 (COX-2) gene were identified to be associated with colorectal cancer (CRC) risk. However, the results are inconsistent. The objective of this meta-analysis was to evaluate the association between these four polymorphisms and the risk of CRC.

MATERIALS AND METHODS

All eligible case-control studies published up to December 2012 on the association between the four polymorphisms of COX-2 and CRC risk were identified by searching PubMed and Web of Science. The CRC risk associated with the four polymorphisms of the COX-2 gene was estimated for each study by odds ratio (OR) together with its 95% confidence interval (CI), respectively.

RESULTS

A total of 15 case-control studies were included. Overall, no evidence has indicated that the -1195A allele, -765C allele, 8473C allele, and 511Ala allele are associated with susceptibility to CRC (-1195G>A: OR=1.11, 95% CI: 0.82-1.51, p=0.78; -765G>C: OR=1.08, 95% CI: 0.96-1.21, p=0.07; 8473T>C: OR=1.03, 95% CI: 0.89-1.18, p=0.91; Val511Ala: OR=0.71, 95% CI: 0.46-1.09, p=0.94). However, stratified analysis with ethnicity indicated that individuals with -765GC or GC/CC genotypes had an increased risk of CRC among Asian populations (GC vs. GG: OR=1.05, 95% CI: 0.87-1.28, p=0.03; GC+CC vs. GG: OR=1.08, 95% CI: 0.96-1.21, p=0.07).

CONCLUSION

This meta-analysis indicated that -765G>C polymorphism was significantly associated with susceptibility to CRC in Asian populations.

Synthesis and chemical and biological comparison of nitroxyl- and nitric oxide-releasing diazeniumdiolate-based aspirin derivatives

Structural modifications of nonsteroidal anti-inflammatory drugs (NSAIDs) have successfully reduced the side effect of gastrointestinal ulceration without affecting anti-inflammatory activity, but they may increase the risk of myocardial infarction with chronic use. The fact that nitroxyl (HNO) reduces platelet aggregation, preconditions against myocardial infarction, and enhances contractility led us to synthesize a diazeniumdiolate-based HNO-releasing aspirin and to compare it to an NO-releasing analogue. Here, the decomposition mechanisms are described for these compounds. In addition to protection against stomach ulceration, these prodrugs exhibited significantly enhanced cytotoxcity compared to either aspirin or the parent diazeniumdiolate toward nonsmall cell lung carcinoma cells (A549), but they were not appreciably toxic toward endothelial cells (HUVECs). The HNO-NSAID prodrug inhibited cylcooxgenase-2 and glyceraldehyde 3-phosphate dehydrogenase activity and triggered significant sarcomere shortening on murine ventricular myocytes compared to control. Together, these anti-inflammatory, antineoplasic, and contractile properties suggest the potential of HNO-NSAIDs in the treatment of inflammation, cancer, or heart failure.

Enhanced 5-fluorouracil cytotoxicity in high COX-2 expressing hepatocellular carcinoma cells by wogonin via the PI3K/Akt pathway

Combination therapies may increase the antitumor effects and reduce the adverse effects for the treatment of hepatocellular carcinoma. In this study, we determined the effects of 5-fluorouracil alone or in combination with wogonin in vitro and in vivo, and we investigated the possible mechanisms. The combination of these 2 drugs led to a decrease in survival and a significant synergistic inhibitory effect on high COX-2 expression in SMMC-7721 hepatocellular carcinoma (HCC) cells. Furthermore, the results show that this combination inhibits COX-2 expression and increases sensitivity to chemotherapeutic agents partly through regulating the PI3K/Akt signaling pathway. Moreover, the combination treatment caused a significant growth inhibition of human tumor xenografts in vivo. In conclusion, wogonin may increase the cytotoxicity of some antineoplastic agents and it can be used in combination with these agents as a novel therapeutic regimen for HCC treatment.

Combination of celecoxib and doxorubicin increases growth inhibition and apoptosis in acute myeloid leukemia cells

Cyclooxygenase-2 (COX-2) inhibitors have been shown to enhance antitumor activity of therapeutic agents in a variety of solid tumor cells. However, this has not been well established in hematopoietic tumors, especially in acute myeloid leukemia (AML). This study was designed to investigate the effects of the combination of celecoxib, a specific COX-2 inhibitor, and doxorubicin on cell growth and apoptosis in human leukemia cells. Co-treatment with celecoxib and doxorubicin significantly inhibited cell growth and induced cell apoptosis in the acute leukemia cell line HL60 and primary AML cells. The growth inhibition effect was accompanied by down-regulation of the expression of cyclin E and cyclin-dependent kinase 2 (CDK2), the key regulators of cell cycle progression, which was associated with arrest of cells at G0/G1 phase. The pro-apoptotic effect was accompanied by down-regulation of the expression of survivin, an inhibitor of apoptosis protein, which mediated anti-apoptosis in AML cells. These results provide the first evidence that the growth inhibitory and pro-apoptotic effects of celecoxib and doxorubicin on AML cells are synergistic.

Altered prostanoid signaling contributes to increased skin tumorigenesis in Tpl2 knockout mice

Squamous cell carcinoma is the second most common form of skin cancer with the incidence expected to double over the next 20 years. Inflammation is believed to be a critical component in skin cancer progression. Therefore, understanding genes involved in the regulation of inflammatory pathways is vital to the design of targeted therapies. Numerous studies show cyclooxygenases (COXs) play an essential role in inflammation-associated cancers. Tpl2 (MAP3K8) is a protein kinase in the MAP Kinase signal transduction cascade. Previous research using a two-stage skin carcinogenesis model revealed that Tpl2^−/− mice have significantly higher tumor incidence and inflammatory response than wild-type (WT) controls. The current study investigates whether cyclooxygenase-2 (COX-2) and COX-2- regulated prostaglandins and prostaglandin receptors drive the highly tumorigenic state of Tpl2^−/− mice by investigating the relationship between Tpl2 and COX-2. Keratinocytes from newborn WT or Tpl2^−/− mice were treated with 12-O-tetradecanoylphorbol-13-acetate (TPA) for various times over 24 hours. Western analysis revealed significant differences in COX-2 and COX-2 dependent prostanoids and prostanoid receptors. Additionally, in vivo experiments confirmed that COX-2 and COX-2 downstream factors were elevated in TPA-treated Tpl2^−/− skin, as well as in papillomas from Tpl2^−/− mice. Use of the selective COX-2 inhibitor Celecoxib showed the increased tumorigenesis in the Tpl2^−/− mice to primarily be mediated through COX-2. These experiments illustrate COX-2 induction in the absence of Tpl2 may be responsible for the increased tumorigenesis found in Tpl2^−/− mice. Defining the relationship between Tpl2 and COX-2 may lead to new ways to downregulate COX-2 through the modulation of Tpl2.

High expression of cyclooxygenase-2 in uterine fibroids and its correlation with cell proliferation

OBJECTIVE

To investigate the expression of cyclooxygenase-2 (COX-2) in uterine fibroids and healthy uterine smooth muscle as well as its role in the pathogenesis of uterine fibroids.

METHODS

We collected uterine fibroid tissues and their paired adjacent healthy uterine smooth muscle tissues from 30 cases of uterine fibroids. We used immunohistochemistry and quantitative real-time PCR, as well as western blot to detect COX-2 expression. Using the COX-2 inhibitors NS-398 and celecoxib, we observed the response to the inhibitors in the healthy and fibroid smooth muscle cell pairs.

RESULTS

COX-2 was detected by immunohistochemistry in both uterine fibroids and uterine smooth muscle, with higher immunoreactivity in uterine fibroids; the positive index of the smooth muscle cells was 11.90 and the positive index of uterine fibroids cells was 46.50 (P<0.05). The expression of COX-2 mRNA in uterine fibroids was higher (0.122±0.062) than in normal smooth muscle tissue (0.025±0.009; P<0.05). Also, the western blot results showed that COX-2 expression was significantly higher in uterine fibroid cases, as compared to the expression in uterine smooth muscle. Immunofluorescence showed that the occurrence of COX-2 was obviously higher in smooth muscle cells of uterine fibroids than in the healthy smooth muscle cells. NS-398 or celecoxib significantly inhibited the proliferation of smooth muscle cells of uterine fibroids, but did not inhibit the proliferation of healthy smooth muscle cells. Accordingly, NS-398 or celecoxib significantly reduced the expression of the downstream metabolite of COX-2, PGE2, in the smooth muscle cells of uterine fibroids, but not in healthy smooth muscle cells.

CONCLUSION

COX-2 expression in uterine fibroids was significantly higher than in healthy uterine smooth muscles. The inhibition of COX-2 activity significantly reduced the proliferation of smooth muscle cells of the uterine fibroids, suggesting that COX-2 plays an important role in the pathogenesis of uterine fibroids.

Sodium arsenite induces cyclooxygenase-2 expression in human uroepithelial cells through MAPK pathway activation and reactive oxygen species induction

Arsenic can induce reactive oxygen species (ROS) leading to oxidative stress and carcinogenesis. Bladder is one of the major target organs of arsenic, and cyclooxygenase-2 (COX-2) may play an important role in arsenic-induced bladder cancer. However, the mechanism by which arsenic induces COX-2 in bladder cells remains unclear. This study aimed at investigating arsenic-mediated intracellular redox status and signaling cascades leading to COX-2 induction in human uroepithelial cells (SV-HUC-1). SV-HUC-1 cells were exposed to sodium arsenite and COX-2 expression, mitogen-activated protein kinase (MAPK) phosphorylation, glutathione (GSH) levels, ROS induction and Nrf2 expression were quantified. Our results demonstrate that arsenite (1-10 μM) elevates COX-2 expression, GSH levels, ROS and Nrf2 expression. Arsenite treatment for 24h stimulates phosphorylation of ERK and p38, but not JNK in SV-HUC-1 cells. Induction of Cox-2 mRNA levels by arsenite was attenuated by inhibitors of ERK, p38 and JNK. Arsenite-induced ROS generation and COX-2 expression were significantly attenuated by treatment with melatonin (a ROS scavenger), but enhanced by DL-buthionine-(S, R)-sulfoximine (BSO, an inhibitor of gamma-glutamylcysteine synthetase (γ-GCS) resulting in lower GSH and increased ROS levels). These data indicate that arsenite promotes an induction of ROS, which results in an induction of COX-2 expression through activation of the MAPK pathway.

The ETS-Domain Transcription Factor Elk-1 Regulates COX-2 Gene Expression and Inhibits Glucose-Stimulated Insulin Secretion in the Pancreatic β -Cell Line INS-1

Cyclooxygenase-2 (COX-2) expression is associated with many aspects of physiological and pathological conditions, including pancreatic β -cell dysfunction. Prostaglandin E2 (PGE2) production, as a consequence of COX-2 gene induction, has been reported to impair β -cell function. The molecular mechanisms involved in the regulation of COX-2 gene expression are not fully understood. We previously demonstrated that transcription factor Elk-1 significantly upregulated COX-2 gene promoter activity. In this report, we used pancreatic β -cell line (INS-1) to explore the relationships between Elk-1 and COX-2. We first investigated the effects of Elk-1 on COX-2 transcriptional regulation and expression in INS-1 cells. We thus undertook to study the binding of Elk-1 to its putative binding sites in the COX-2 promoter. We also analysed glucose-stimulated insulin secretion (GSIS) in INS-1 cells that overexpressed Elk-1. Our results demonstrate that Elk-1 efficiently upregulates COX-2 expression at least partly through directly binding to the -82/-69 region of COX-2 promoter. Overexpression of Elk-1 inhibits GSIS in INS-1 cells. These findings will be helpful for better understanding the transcriptional regulation of COX-2 in pancreatic β -cell. Moreover, Elk-1, the transcriptional regulator of COX-2 expression, will be a potential target for the prevention of β -cell dysfunction mediated by PGE2.

Molecular mechanisms of anti-inflammatory action of the flavonoid, tricin from Njavara rice (Oryza sativa L.) in human peripheral blood mononuclear cells: possible role in the inflammatory signaling

Flavonoids are a group of natural substances that are located in sources of vegetal origin and are able to regulate acute and chronic inflammatory responses. The anti-oxidant and anti-inflammatory effects corroborate with the preferential use of Njavara, a rice variety in indigenous medicine and the phytochemical investigations revealed the occurrence of a flavonoid, tricin at significantly higher levels compared to staple varieties. This study describes the new aspects of inflammatory suppression by the Njavara rice by evaluating the role of active constituent, tricin in the regulation of production of various pro-inflammatory markers by human peripheral blood mononuclear cells stimulated with lipopolysaccharide. Treatment with tricin resulted in significant down-regulation of LPS-elicited production of TNF-α, IL-6, PGE(2) and NO. Tricin was found to be a potential blocker of the expression of isoforms of nitric oxide synthase, cyclooxygenase and matrix metalloproteinases. Modulation of the cascade of molecular events in lipopolysaccharide signaling also includes inhibition of transcription factor NF-κB evidenced by the detection of enhanced p65 subunit in the nuclear extracts on tricin supplementation. The present study summarizes the role of the flavonoid, tricin in the modulation of the expression of different inflammatory mediators and revealed that the inhibitory effects on cell signaling pathways are responsible for its anti-inflammatory activity.

siRNA-mediated knock-down of COX-2 in melanocytes suppresses melanogenesis

Cyclooxygenase-2 (COX-2) is an enzyme induced in response to multiple mitogenic and inflammatory stimuli, including UV light. UV-induced COX-2 expression induces production of prostaglandin E2 (PGE2) in keratinocytes, which mediates inflammation and cell proliferation. Until recently, studies regarding COX-2 and PGE2 in the skin have focused on keratinocytes and skin cancer and the effect of PGs produced by keratinocytes on melanocytes. However, the effects of COX-2 itself or COX-2 inhibitors on melanogenesis are not well known. Therefore, to establish the role of COX-2 in melanogenesis, we investigated the effects of knock-down of COX-2 in melanocytes on melanin production and the expression of melanogenic molecules through silencing of COX-2 expression with COX-2 short interfering RNA (siRNA). COX-2 knock-down in melanocytes decreased the expressions of tyrosinase, TRP-1, TRP-2, gp100 and MITF and also reduced tyrosinase enzyme activity. Furthermore, COX-2 siRNA-transfected melanocytes showed markedly reduced alpha-melanocyte stimulating hormone (α-MSH)-induced melanin production. In addition, α-MSH-induced COX-2 expression in both scrambled siRNA-transfected and COX-2 siRNA-transfected melanocytes was greater than α-MSH-untreated cells. Our results suggest that COX-2 might be a candidate target for the development of anti-melanogenic agents and α-MSH-induced pigmentation could be closely associated with COX-2 expression. COX-2 inhibitors might therefore be of particular use in whitening cosmetics for hyperpigmentation disorders such as melasma, postinflammatory hyperpigmentation and solar lentigo.

A genetic variant in 3'-untranslated region of cyclooxygenases-2 gene is associated with risk of gastric cancer in a Chinese population

Cyclooxygenase-2 (COX-2) involves in multiple processes in carcinogenesis, including inflammation, apoptosis inhibition, immune response suppression, tumor cell invasion, and angiogenesis. COX-2 is overexpressed in various cancers, including gastric cancer. COX-2 is encoded by prostaglandin endoperoxide synthase 2 (PTGS2) gene. We hypothesized that potentially functional polymorphisms in PTGS2 may contribute to gastric cancer risk. To assess this hypothesis, we conducted a case-control study with 1681 gastric cancer cases and 1916 control subjects in a Chinese population to evaluate the association between a polymorphism in 3'-untranslated region of PTGS2, rs5275, and the risk of gastric cancer. Logistic regression analysis revealed that variant allele (C) of rs5275 was significantly associated with an increased risk of gastric cancer (per allele odds ratio [OR] = 1.14, 95% confidence interval [CI] = 1.01-1.29, p = 0.030). This association was more prominent in females (per allele OR = 1.42, 95% CI = 1.11-1.81, p = 0.005) and nonsmokers (per allele OR = 1.35, 95% CI = 1.14-1.59, p = 0.001). Interestingly, we detected a negative interaction between rs5275 and smoking on the gastric cancer risk (p = 0.007). Our findings indicate that PTGS2 rs5275T/C may be a candidate genetic marker for gastric cancer susceptibility.

PTGS2 (COX2) -765G>C gene polymorphism and risk of sporadic colorectal cancer in Iranian population

Colorectal cancer (CRC) is one of the leading cancers worldwide. Through genome wide association studies, several single nucleotide polymorphisms scattered in the genome emerged to be influential in the development of sporadic CRC in some populations. However, replicative studies failed to prove a particular SNP-CRC association in populations and ethnic groups. Cyclooxygenase-2 (PTGS2) is a crucial enzyme involved in the metabolism of prostaglandins. The aim of this replicative study is to investigate the possible association between PTGS2 -765G>C polymorphism and sporadic CRC risk in a subset of Iranian population. A total of 110 patients with sporadic CRC, and 120 controls were genotyped for PTGS2 -765G>C polymorphism by using polymerase chain reaction-based restriction fragment length polymorphism. There were no significant differences in the genotype and allele frequencies of PTGS2 -765G>C between two groups except in irregular aspirin or non-steroidal anti-inflammatory drugs (NSAID) consumers. Frequencies of genotypes and alleles were as follows: GG = 44.2, GC = 48.3, CC = 7.5%, in controls and GG = 34.55, GC = 60.9, CC = 4.55% in cases. Regarding the allele frequency, the following values were found: G = 65, C = 35% in cases and 68.3, 31.7% in the controls, respectively. In irregular aspirin or NSAID consumers combined GC+CC genotype was found to be a risk genotype (OR = 1.933, 95% CI: 1.067-3.501, P = 0.036). Overall, no significant relation was found between this polymorphism and sporadic CRC in Iranians. However, in irregular aspirin or NSAID consumers the combined GC+CC genotype proved to be a risk genotype.

DNA polymorphisms and tissue cyclooxygenase-2 expression in oral lichen planus: a case-control study

BACKGROUND

Oral lichen planus (OLP) is a chronic inflammatory disorder defined as a precancerous condition. Special attention has been paid to the expression of cyclooxygenase-2 (COX-2) and its potential role in development of oral squamous cell carcinoma. The identification of single nucleotide polymorphisms that affect gene function or expression and contribute to disease predisposition has become a major area of investigation toward understanding the mechanisms for cancer.

OBJECTIVE

The objective of this study is to investigate the association between the COX-2 765G>C gene polymorphism, tissue COX-2 expression and the development of OLP as a chronic inflammatory condition.

METHODS

This study was done on 50 patients with OLP and 50 healthy controls. COX-2 activity was assessed by measuring tissue prostaglandin E (PGE)2 levels by enzyme immunometric assay kit. COX-2 765G>C gene polymorphism was assessed by reverse transcriptase-polymerase chain reaction (RT-PCR) followed by restricted fragment length polymorphism (RFLP).

RESULTS

OLP patients showed statistically significant higher mean PGE2 than the control group. We did not observe any statistically significant differences in genotype distribution or allele frequency between the patients and the control group (P > 0.05). Odds ratio showed no statistically significant association between COX-2 765G>C polymorphism and lichen planus.

CONCLUSION

The present evidence thus indicates that variation in the COX-2 gene is unlikely to be of relevance to the aetiology of OLP. As this is the first report concerning the COX-2 -765G>C gene polymorphism and the risk of OLP, additional studies with larger sample size will be required to confirm these findings.

Analysis of promoters and expression-targeted gene therapy optimization based on doubling time and transfectability

Genes under the control of the cyclooxygenase-2 (Cox-2), human epidermal growth factor receptor 2 (Her-2), and survivin promoters were constructed and delivered to murine and human carcinoma cells. It was found that (P)Cox-2-driven reporter expression was strong and correlated well with endogenous Cox-2 levels, while (P)Her-2 and (P)survivin yielded poor results, consistent with the three distinct expression mechanisms used by cancer cells to overexpress the endogenous versions of the selected genes. The (P)Cox-2 was then used to drive the expression of caspase genes both in vitro and in vivo to bring about targeted apoptosis of carcinoma cells successfully. The results led to the following conclusions. 1) When selecting a promoter/enhancer for expression-targeted gene delivery, it is not enough to perform a microarray on some tumor tissue and select the control element associated with the greatest amount of gene up-regulation vs. normal controls. The mechanism of expression for the particular gene should be taken into account to prevent lengthy and costly research trials. 2) When overexpression is due to activator binding, a predictive model based on endogenous gene expression levels, overall cell transfectability, and cell doubling rates can be used to predict expression-targeted gene delivery outcomes with significant accuracy.