Benzo[a]pyrene up-regulates cyclooxygenase-2 gene expression in oral epithelial cells

Immunohistochemical analysis and correlation of cyclooxygenase-2 expression status with clinicopathological parameters in head and neck squamous cell carcinomas: An Indian perspective

Context:

Head and neck squamous cell carcinoma (HNSCC) poses a major health problem and despite the advancements in its diagnosis and management the overall survival has not improved significantly. A search for newer diagnostic and prognostic markers along with fresh molecular targets is required for its prevention and cure.

Aims:

The study aims to study the expression of cyclooxygenase-2 (COX-2) in HNSCCs and investigate its correlation with the clinicopathological profile of these cases. This study was performed to determine the significance of COX-2 expression in the Indian context.

Settings and Design:

This study incorporated 90 cases of HNSCCs; both prospectively and retrospectively in a tertiary care center.

Materials and Methods:

Expression of COX-2 on immunohistochemistry (IHC) was evaluated in correlation with the histological grade, maximum tumor size, tumor depth, nodal status and lymphovascular/perineural invasion (lvi/pni). The study received a waiver from the institutional ethics committee.

Statistical Analysis Used:

Statistical analysis of the data was done using SPSS software.

Results:

COX-2 expression was found in 97.8% of the cases. A statistically significant correlation of COX-2 immunopositivity was found with the histological grade, clinical staging (tumor size and nodal status), maximum tumor depth and lvi/pni in our study (P < 0.05).

Conclusions:

COX-2 is expressed by most of the cases in this study. Its expression is related to tumor growth, differentiation and aggressiveness and therefore can be used as a good independent prognostic marker in HNSCCs. There is also possible scope of using it for targeted therapy in HNSCCs.

Exploration of interaction mechanism of tyrosol as a potent anti-inflammatory agent

Drug discovery for a vigorous and feasible lead candidate is a challenging scientific mission as it requires expertise, experience, and huge investment. Natural products and their derivatives having structural diversity are renowned source of therapeutic agents since many years. Tyrosol (a natural phenylethanoid) has been extracted from olive oil, and its structure was confirmed by elemental analysis, FT-IR, FT-NMR, and single crystal X-ray crystallography. The conformational analysis for tyrosol geometry was performed by Gaussian 09 in terms of density functional theory. Validation of bond lengths and bond angles obtained experimentally as well as theoretically were performed with the help of curve fitting analysis, and values of correlation coefficient (R) obtained as 0.988 and 0.984, respectively. The charge transfer within the tyrosol molecule was confirmed by analysis of HOMO→LUMO molecular orbitals. In molecular docking with COX-2 (PDB ID: 5F1A), tyrosol was found to possess satisfactory binding affinity as compared to other NSAIDs (Aspirin, Ibuprofen, and Naproxen) and a COX-2 selective drug (Celecoxib). ADMET prediction, drug-likeness and bioactivity score altogether confirm the lead/drug like potential of tyrosol. Further investigation of simulation quality plot, RMSD and RMSF plots, ligands behavior plot as well as post simulation analysis manifest the consistency of 5F1A-tyrosol complex throughout the 20 ns molecular simulation process that signifies its compactness and stability within the receptor pocket. AbbreviationsADMETAbsorption, Distribution, Metabolism, Excretion and ToxicityÅAngstromCOX-2Cyclooxygenase-2DFTDensity Functional TheoryDMFDimethylformamideFMOFrontier Molecular OrbitalFT-IRFourier-transform Infrared SpectroscopyFT-NMRNuclear Magnetic Resonance SpectroscopyHOMOHighest Occupied Molecular OrbitalLUMOLowest Unoccupied Molecular OrbitalMDMolecular DynamicsNSNanosecondNSAIDsNon-steroidal anti-inflammatory drugsOPEOsiris Property ExplorerRMSDRoot-Mean-Square DeviationRMSFRoot Sean Square FluctuationCommunicated by Ramaswamy H. Sarma.

Resolvin D1 down-regulates CYP1A1 and PTGS2 gene in the HUVEC cells treated with benzo(a)pyrene

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) can interact with lipids and their derivatives and have been known to induce atherosclerosis. The aim of this study was to evaluate the impact of Resolvin D1 (RvD1) on inflammatory-state realted proteins and genes in the human primary umbilical vein endothelial HUVEC cells exposed to benzo(a)pyrene (BaP).

METHODS

We analyzed the influence of RvD1 and/or BaP on cyclooxygenase-2 (COX-2), cytosolic prostaglandine E2 synthase (cPGES), glutathione S transferase (GSTM1) and aryl hydrocarbon receptor (AhR) protein expression by Western blot. Additionaly, phospholipase A2 (cPLA2) and cytochrome P450 (CYP1A1) activity, as well as AhR, CYP1A1, phospholipase A2 (PLA2G4A) and prostaglandin synthase 2 (PTGS2) gene expression by qRT-PCR was studied.

RESULTS

RvD1 down-regulates cytochrome P450 (CYP1A1) and prostaglandin synthase 2 (PTGS2) gene expression in HUVEC cells exposed to BaP. Repressesion of COX-2, cPGES and overexpressesion of GSTM1 protein was noted after co-treatment with RvD1 and BaP. After incubation with RvD1 an increase of cPLA2 and a decrease of CYP1A1 activity was observed when compared to BaP treated alone endothelial cells.

CONCLUSIONS

Our data suggests that RvD1 can significantly contributes on vascular function and alleviates the harmful effects caused by BaP, which might potentially aid in the repair of the injured endothelium.

Lupeol evokes anticancer effects in oral squamous cell carcinoma by inhibiting oncogenic EGFR pathway

Epidermal growth factor receptor (EGFR) pathway is overexpressed in head and neck cancer (HNC). Lupeol, a natural triterpene (phytosterol found in fruits, vegetables, etc.), has been reported to be effective against multiple cancer indications. Here we investigate the antitumor effects of Lupeol and underlying mechanism in oral cancer. Lupeol-induced antitumor response was evaluated in two oral squamous cell carcinoma (OSCC) cell lines (UPCI:SCC131 and UPCI:SCC084) by viability (MTT), proliferation, and colony formation assays. Lupeol-mediated induction of apoptosis was examined by caspase 3/7 assay and flow cytometry. Effect of Lupeol on EGFR in the presence or absence of EGF was delineated by Western blot. The mRNA stability assay was performed to check the role of Lupeol on COX-2 mRNA regulation. Lupeol inhibited proliferation of OSCC cells in vitro by inducing apoptosis 48 h post treatment. Ligand-induced phosphorylation of EGFR and subsequent activation of its downstream molecules such as protein kinase B (PKB or AKT), I kappa B (IκB), and nuclear factor kappa B (NF-κB) was also found to be, in part, suppressed. Interestingly, Lupeol suppressed expression of COX-2 at mRNA and protein level in a time-dependent manner. Primary explants from oral squamous cell carcinoma tissues further confirmed significant inhibition of proliferation (Ki67) in Lupeol-treated explants as compared to untreated control at 48 h. Together these data suggest that Lupeol may act as a potent inhibitor of the EGFR signaling in OSCC and therefore imply its role in triggering antitumor efficacy.

Elevated Levels of Urinary PGE-M Are Found in Tobacco Users and Indicate a Poor Prognosis for Oral Squamous Cell Carcinoma Patients

Cyclooxygenase-2 (COX-2)-derived prostaglandin E2 (PGE2) plays a role in the development and progression of epithelial malignancies. Measurements of urinary PGE-M, a stable metabolite of PGE2, reflect systemic PGE2 levels. Here, we investigated whether urinary PGE-M levels were elevated in healthy tobacco users and in patients with oral squamous cell carcinoma (OSCC). Median urinary PGE-M levels were increased in healthy tobacco quid chewers [21.3 ng/mg creatinine (Cr); n = 33; P = 0.03] and smokers (32.1 ng/mg Cr; n = 31; P < 0.001) compared with never tobacco quid chewers-never smokers (18.8 ng/mg Cr; n = 30). Urinary PGE-M levels were also compared in OSCC patients versus healthy tobacco users. An approximately 1-fold increase in median urinary PGE-M level was found in OSCC patients (48.7 ng/mg Cr, n = 78) versus healthy controls (24.5 ng/mg Cr, n = 64; P < 0.001). We further determined whether baseline urinary PGE-M levels were prognostic in OSCC patients who underwent treatment with curative intent. A nearly 1-fold increase in baseline urinary PGE-M levels (64.7 vs. 33.8 ng/mg Cr, P < 0.001) was found in the group of OSCC patients who progressed (n = 37) compared with the group that remained progression free (n = 41). Patients with high baseline levels of urinary PGE-M had both worse disease-specific survival [HR, 1.01 per unit increase; 95% confidence interval (CI), 1.01-1.02; P < 0.001] and overall survival (HR, 1.01 per unit increase; 95% CI, 1.00-1.02; P = 0.03). Taken together, our findings raise the possibility that NSAIDs, prototypic inhibitors of PGE2 synthesis, may be beneficial for reducing the risk of tobacco-related aerodigestive malignancies or treating OSCC patients with high urinary PGE-M levels. Cancer Prev Res; 9(6); 428-36. ©2016 AACR.

n-3 Fatty acids regulate the inflammatory-state related genes in the lung epithelial cells exposed to polycyclic aromatic hydrocarbons

BACKGROUND

Chronic airway inflammation is coordinated by a complex of inflammatory mediators, including eicosanoids. The aim of this study was to evaluate the impact of polycyclic aromatic hydrocarbons (PAHs) on the human lung epithelial carcinoma A549 cells supplemented with docosahexaenoic (DHA) and eicosapentaenoic (EPA) acids.

METHODS

We analyzed the influence of DHA, EPA and/or benzo(a)pyrene (BaP), chrysene (Chr), fluoranthene (Flu) and benzo(a)anthracene (Baa) treatment on the fatty acids (FAs) profile and the formation of isoprostanes. We studied the cyclooxygenase-2, FP-receptor, peroxisome proliferator-activated receptors PPARδ and PPARγ, transcription factor NF-кB p50 and p65 expression by Western blot, phospholipase A2 (cPLA2) activity, as well as aryl hydrocarbon receptor (AHR), cytochrome P450 (CYP1A1), phospholipase A2 (PLA2G4A) and prostaglandin synthase 2 (PTGS2) gene expression by qRT-PCR.

RESULTS

DHA or EPA supplementation and BaP or Baa treatment resulted in a higher level of PGF3α. COX-2 expression was decreased while PPARδ expression and cPLA2 activity was increased after fatty acid supplementation and PAHs treatment. DHA and EPA up-regulated AHR and PLA2G4A genes.

CONCLUSIONS

Supplementation with n-3 FAs resulted in changes of inflammatory-state related genes in the lung epithelial cells exposed to PAHs. The altered profile of lipid mediators from n-3 FA as well as repression of the COX-2 protein by n-3 PUFAs in A549 cells incubated with PAHs suggests anti-inflammatory and pro-resolving properties of DHA and EPA. It remains to be shown whether these pleiotropic and protective actions of n-3 FAs contribute to fish oil's therapeutic effect in asthma.

Docosahexaenoic acid regulates gene expression in HUVEC cells treated with polycyclic aromatic hydrocarbons

The molecular mechanism of inflammation and carcinogenesis induced by exposure of polycyclic aromatic hydrocarbons (PAHs) is not clearly understood. Our study was undertaken due to the strong pro-carcinogenic potential and reactivity of PAH-metabolites, as well as the susceptibility of polyunsaturated fatty acids to oxidation. The aim of this study was to evaluate the pro- or anti-inflammatory impact of n-3 docosahexaenoic acid on human primary umbilical vein endothelial cells (HUVEC) exposed to polycyclic aromatic hydrocarbons. We analysed the influence of docosahexaenoic acid (DHA) and/or PAHs supplementation on the fatty acid profile of cell membranes, on cyclooxygenase-2 (COX-2), aryl hydrocarbon receptor (AHR), and glutathione S transferase Mu1 (GSTM1) protein expression as well as on the prostaglandin synthase 2 (PTGS2), AHR, GSTM1, PLA2G4A, and cytochrome P450 CYP1A1 gene expression. We observed that COX-2 and AHR protein expression was increased while GSTM1 expression was decreased in cells exposed to DHA and PAHs. Docosahexaenoic acid down-regulated CYP1A1 and up-regulated the AHR and PTGS2 genes. Our findings suggested that DHA contributes significantly to alleviate the harmful effects caused by PAHs in endothelial cells. Moreover, these results suggest that a diet rich in n-3 fatty acids is helpful to reduce the harmful effects of PAHs exposure on human living in heavily polluted areas.

Design, synthesis and structure-activity relationship studies of novel and diverse cyclooxygenase-2 inhibitors as anti-inflammatory drugs

Because of the pivotal role of cyclooxygenase (COX) in the inflammatory processes, non-steroidal anti-inflammatory drugs (NSAIDs) that suppress COX activities have been used clinically for the treatment of inflammatory diseases/syndromes; however, traditional NSAIDs exhibit serious side-effects such as gastrointestinal damage and hyper sensitivity owing to their COX-1 inhibition. Also, COX-2 inhibition-derived suppressive or preventive effects against initiation/proliferation/invasion/motility/recurrence/metastasis of various cancers/tumours such as colon, gastric, skin, lung, liver, pancreas, breast, prostate, cervical and ovarian cancers are significant. In this study, design, synthesis and structure-activity relationship (SAR) of various novel {2-[(2-, 3- and/or 4-substituted)-benzoyl, (bicyclic heterocycloalkanophenyl)carbonyl or cycloalkanecarbonyl]-(5- or 6-substituted)-1H-indol-3-yl}acetic acid analogues were investigated to seek and identify various chemotypes of potent and selective COX-2 inhibitors for the treatment of inflammatory diseases, resulting in the discovery of orally potent agents in the peripheral-inflammation model rats. The SARs and physicochemical properties for the analogues are described as significant findings. For graphical abstract: see Supplementary Material. ( www.informahealthcare.com/enz ).

Src mediates ERK reactivation in gefitinib resistance in non-small cell lung cancer

To study epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) resistance mechanisms, we established a novel gefitinib-resistant lung cancer cell line derived from an EGFR-mutant non-small cell lung cancer cell line (PC-9) pretreated with 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (designated PC9-GR). We found that gefitinib substantially suppressed the EGFR signaling pathway, whereas ERK was reactivated after several hours in PC9-GR but not in PC-9. The combination of gefitinib with ERK inhibition (by U0126) restored gefitinib susceptibility in PC9-GR, but PI3K-Akt inhibition with LY294002 did not. Although the levels of phosphorylated Src were up-regulated simultaneously with ERK reactivation, neither ERK suppression using U0126 nor an ERK-specific siRNA induced Src phosphorylation. Furthermore, dual inhibition of EGFR and Src restored gefitinib sensitivity in PC9-GR in vitro and in vivo. In conclusion, our results indicate that Src-mediated ERK reactivation may play a role in a novel gefitinib resistance mechanism, and that the combined use of gefitinib with a Src inhibitor may be a potent strategy to overcome this resistance.

The impact of sphingosine kinase-1 in head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) has a high reoccurrence rate and an extremely low survival rate. There is limited availability of effective therapies to reduce the rate of recurrence, resulting in high morbidity and mortality of advanced cases. Late presentation, delay in detection of lesions, and a high rate of metastasis make HNSCC a devastating disease. This review offers insight into the role of sphingosine kinase-1 (SphK1), a key enzyme in sphingolipid metabolism, in HNSCC. Sphingolipids not only play a structural role in cellular membranes, but also modulate cell signal transduction pathways to influence biological outcomes such as senescence, differentiation, apoptosis, migration, proliferation, and angiogenesis. SphK1 is a critical regulator of the delicate balance between proliferation and apoptosis. The highest expression of SphK1 is found in the advanced stage of disease, and there is a positive correlation between SphK1 expression and recurrent tumors. On the other hand, silencing SphK1 reduces HNSCC tumor growth and sensitizes tumors to radiation-induced death.  Thus, SphK1 plays an important and influential role in determining HNSCC proliferation and metastasis. We discuss roles of SphK1 and other sphingolipids in HNSCC development and therapeutic strategies against HNSCC.

Pattern of expression of cyclooxygenase-2 in malignant transformation of sinonasal inverted papilloma

OBJECTIVE

Cyclooxygenases (COXs) are enzymes that catalyze the conversion of arachidonic acid to prostaglandins. Many studies have suggested that COX-2, the inducible form of COX, is important in carcinogenesis. However, little is known about the pattern of expression of COX-2 in a multistep process of malignant transformation of sinonasal inverted papilloma (IP). In this study, we investigated COX-2 expression in IPs, IPs with dysplasia, IPs with squamous cell carcinoma (SCC), and primary SCCs of sinonasal tract.

STUDY DESIGN

A retrospective study was conducted.

SETTING

The setting was a tertiary care referral center.

SUBJECTS AND METHODS

The expression of COX-2 was evaluated by immunohistochemistry in 56, 7, 18, and 17 cases of IPs, IPs with dysplasia, IPs with SCC, and primary SCCs, respectively. Furthermore, we investigated the possible correlation between the expression of COX-2 and clinicopathologic variables in patients with IPs with SCC and primary SCC patients.

RESULTS

Positive immunoreactivity for COX-2 was observed in 3 (5.4%) of 56 IPs, 7 (38.9%) of 18 IPs with SCC, and 7 (41.2%) of 17 primary SCCs, whereas it was not observed in IPs with dysplasia. The percentage of tumors with COX-2-positive immunostaining was significantly higher in IPs with SCC and primary SCCs compared with benign IPs. There was no significant correlation between the expression of COX-2 and clinicopathologic variables, such as tumor stage, histologic differentiation, and the proportion of malignant areas in patients with IPs with SCC.

CONCLUSION

Cyclooxygenase-2 may play an important role in the process of malignant transformation from IP to SCC.

Reduction in cancer risk by selective and nonselective cyclooxygenase-2 (COX-2) inhibitors

We conducted a series of epidemiologic studies to evaluate the chemopreventive effects of aspirin, ibuprofen, and selective cyxlooxygenase-2 (COX-2) inhibitors (coxibs) against cancers of the breast, colon, prostate, and lung. Composite results across all four cancer sites revealed that regular intake of 325 mg aspirin, 200 mg ibuprofen, or standard dosages of coxibs (200 mg celecoxib or 25 mg rofecoxib) produced risk reductions of 49%, 59%, and 64%, respectively. Use of coxibs for at least 2 years was associated with risk reductions of 71%, 70%, 55%, and 60% for breast cancer, colon cancer, prostate cancer and lung cancer, respectively. Effects of ibuprofen were similar to selective coxibs, and slightly stronger than aspirin. These observed effects are consistent with the relative COX-2 selectivity of ibuprofen, coxibs, and aspirin. Acetaminophen, an analgesic without COX-2 activity, had no effect. Overexpression of COX-2 and increased prostaglandin biosynthesis correlates with carcinogenesis and metastasis at most anatomic sites. These results indicate that regular intake of nonselective or selective COX-2 inhibiting agents protects against the development of major forms of cancer.

Spatial autocorrelation calculations of the nine malignant neoplasms in Taiwan in 2005-2009: a gender comparison study

Spatial analytical techniques and models are often used in epidemiology to identify spatial anomalies (hotspots) in disease regions. These analytical approaches can be used to identify not only the location of such hotspots, but also their spatial patterns. We used spatial autocorrelation methodologies, including Global Moran's I and Local Getis-Ord statistics, to describe and map spatial clusters and areas in which nine malignant neoplasms are situated in Taiwan. In addition, we used a logistic regression model to test the characteristics of similarity and dissimilarity between males and females and to formulate the common spatial risk. The mean found by local spatial autocorrelation analysis was used to identify spatial cluster patterns. We found a significant relationship between the leading malignant neoplasms and well-documented spatial risk factors. For instance, in Taiwan, the geographic distribution of clusters where oral cavity cancer in males is prevalent was closely correspond to the locations in central Taiwan with serious metal pollution. In females, clusters of oral cavity cancer were closely related with aboriginal townships in eastern Taiwan, where cigarette smoking, alcohol drinking, and betel nut chewing are commonplace. The difference between males and females in the spatial distributions was stark. Furthermore, areas with a high morbidity of gastric cancer were clustered in aboriginal townships where the occurrence of Helicobacter pylori is frequent. Our results revealed a similarity between both males and females in spatial pattern. Cluster mapping clarified the spatial aspects of both internal and external correlations for the nine malignant neoplasms. In addition, using a method of logistic regression also enabled us to find differentiation between gender-specific spatial patterns.

Polycyclic aromatic hydrocarbons and digestive tract cancers: a perspective

Cancers of the colon are most common in the Western world. In majority of these cases, there is no familial history and sporadic gene damage seems to play an important role in the development of tumors in the colon. Studies have shown that environmental factors, especially diet, play an important role in susceptibility to gastrointestinal (GI) tract cancers. Consequently, environmental chemicals that contaminate food or diet during preparation become important in the development of GI cancers. Polycyclic aromatic hydrocarbons (PAHs) are one such family of ubiquitous environmental toxicants. These pollutants enter the human body through consumption of contaminated food, drinking water, inhalation of cigarette smoke, automobile exhausts, and contaminated air from occupational settings. Among these pathways, dietary intake of PAHs constitutes a major source of exposure in humans. Although many reviews and books on PAHs and their ability to cause toxicity and breast or lung cancer have been published, aspects on contribution of diet, smoking and other factors toward development of digestive tract cancers, and strategies to assess risk from exposure to PAHs have received much less attention. This review, therefore, focuses on dietary intake of PAHs in humans, animal models, and cell cultures used for GI cancer studies along with epidemiological findings. Bioavailability and biotransformation processes, which influence the disposition of PAHs in body and the underlying causative mechanisms of GI cancers, are also discussed. The existing data gaps and scope for future studies is also emphasized. This information is expected to stimulate research on mechanisms of sporadic GI cancers caused by exposure to environmental carcinogens.

Cyclooxygenase inhibitors: scope of their use and development in cancer chemotherapy

The traditional nonsteroidal anti-inflammatory drugs (NSAIDs) exert their effect by inhibition of cyclooxygenase-1 (COX-1) as well as COX-2 enzymes. As COX-1 is responsible for maintaining normal biological functions, the nonselective inhibition of these enzymes caused side effects including gastrointestinal (GI) problems. Recently developed selective COX-2 inhibitors could reduce these adverse effects, but the evidence of cardiovascular side effects including an increased risk of myocardial infarction began to emerge, and some of the COX-2 inhibitors were eventually withdrawn from the market and this led to the downfall of this research. So, the discovery of novel COX-2 inhibitors with their safety profile became the biggest challenge in pharmaceutical research. However, recent mechanistic and clinical studies revolutionized this area by indicating the fact that COX-2 is involved in apoptosis resistance, angiogenesis, and tumor progression. Epidemiological data suggest that selective COX-2 inhibitors might prevent the development of cancers. Moreover, COX-2 is found to be overexpressed in many cancers thus making it an attractive therapeutic target for the prevention and treatment of a number of malignancies. The purpose of this review is to focus on the medicinal chemistry aspects of COX-2 inhibitors in cancer chemotherapy and recent reports on these inhibitors as anticancer agents. We attempted to cover only the COX inhibitors that showed anticancer activity, although a number of potent COX-2 inhibitors have been reported without their anticancer effects. Furthermore, structure-activity relationships (SAR) of different classes of compounds for COX-2 inhibition as well as anticancer activity, and their future applications are discussed.

Oolong tea theasinensins attenuate cyclooxygenase-2 expression in lipopolysaccharide (LPS)-activated mouse macrophages: structure-activity relationship and molecular mechanisms

Oolong tea theasinensins are a group of tea polyphenols different from green tea catechins and black tea theaflavins. The present study reports the inhibitory effects of oolong tea theasinensins on the expression of cyclooxygenase-2 (COX-2) and underlying molecular mechanisms in lipopolysaccharide (LPS)-activated murine macrophage RAW264 cells. The structure-activity data revealed that the galloyl moiety of theasinensins played an important role in the inhibitory actions. Theasinensin A, a more potent inhibitor, caused a dose-dependent inhibition of mRNA, protein, and promoter activity of COX-2. An electrophoretic mobility shift assay (EMSA) revealed that theasinensin A reduced the complex of NF-κB- and AP-1-DNA in the promoter of COX-2. Signaling analysis demonstrated that theasinensin A attenuated IκB-α degradation, nuclear p65 accumulation, and c-Jun phosphorylation. Furthermore, theasinensin A suppressed the phosphorylation of MAPKs, IκB kinase α/β (IKKα/β), and TGF-β activated kinase (TAK1). These data demonstrated that the down-regulation of TAK1-mediated MAPKs and NF-κB signaling pathways might be involved in the inhibition of COX-2 expression by theasinensin A. These findings provide the first molecular basis for the anti-inflammatory properties of oolong tea theasinensins.

Cigarette smoking, cyclooxygenase-2 pathway and cancer

Cigarette smoking is a major cause of mortality and morbidity worldwide. Cyclooxygenase (COX) and its derived prostanoids, mainly including prostaglandin E2 (PGE2), thromboxane A2 (TxA2) and prostacyclin (PGI2), have well-known roles in cardiovascular disease and cancer, both of which are associated with cigarette smoking. This article is focused on the role of COX-2 pathway in smoke-related pathologies and cancer. Cigarette smoke exposure can induce COX-2 expression and activity, increase PGE2 and TxA2 release, and lead to an imbalance in PGI2 and TxA2 production in favor of the latter. It exerts pro-inflammatory effects in a PGE2-dependent manner, which contributes to carcinogenesis and tumor progression. TxA2 mediates other diverse biologic effects of cigarette smoking, such as platelet activation, cell contraction and angiogenesis, which may facilitate tumor growth and metastasis in smokers. Among cigarette smoke components, nicotine and its derived nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) are the most potent carcinogens. COX-2 and PGE2 have been shown to play a pivotal role in many cancers associated with cigarette smoking, including cancers of lung, gastric and bladder, while the information for the role of TxA2 and PGI2 in smoke-associated cancers is limited. Recent findings from our group have revealed how NNK influences the TxA2 to promote the tumor growth. Better understanding in the above areas may help to generate new therapeutic protocols or to optimize the existing treatment strategy.

Anti-carcinogenic effects of sulforaphane in association with its apoptosis-inducing and anti-inflammatory properties in human cervical cancer cells

BACKGROUND

The multistep process of carcinogenesis is characterized by progressive disorganization and occurrence of initiation, promotion, and progression events. Several new strategies such as chemoprevention are being developed for treatment and prevention at various stages of carcinogenesis. Sulforaphane, a potential chemopreventive agent, possesses anti-proliferative, anti-inflammatory, anti-oxidant and anti-cancer activities and has attracted extensive interest for better cancer management.

METHODS

We evaluated the effect of sulforaphane alone or in combination with gemcitabine on HeLa cells by cell viability assay and confirmed the results by apoptosis assay. Further we analyzed the effect of sulforaphane on the expression of Bcl-2, COX-2 and IL-1β by RT-PCR on HeLa cells.

RESULTS

In the present study, sulforaphane was found to induce dose-dependent selective cytotoxicity in HeLa cells in comparison to normal cells pointing to its safe cytotoxicity profile. Additionally, a combination of sulforaphane and gemcitabine was found to increase the growth inhibition in a synergistic manner in HeLa cells compared to the individual drugs. Also, the expression analysis of genes involved in apoptosis and inflammation revealed significant downregulation of Bcl-2, COX-2 and IL-1β upon treatment with sulforaphane.

CONCLUSION

Our results suggest that sulforaphane exerts its anticancer activities via apoptosis induction and anti-inflammatory properties and provides the first evidence demonstrating synergism between sulforaphane and gemcitabine which may enhance the therapeutic index of prevention and/or treatment of cervical cancer.

4-Methylnitrosamino-1-3-pyridyl-1-butanone (NNK) promotes lung cancer cell survival by stimulating thromboxane A2 and its receptor

The role of thromboxane A(2) (TxA(2)) in smoking-associated lung cancer is poorly understood. This study was conducted to study the role of TxA(2) in smoking carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)-promoted cell survival and growth in human lung cancer cells. We found that NNK increased TxA(2) synthase (TxAS) expression and thromboxane B(2) (TxB(2)) generation in cultured lung cancer cells, the result of which was supported by the increased level of TxAS in lung cancer tissues of smokers. Both TxAS-specific inhibitor furegrelate and TxA(2) receptor antagonist SQ29548 completely blocked NNK-mediated cell survival and growth via inducting apoptosis. TxA(2) receptor agonist U46619 reconstituted a near-full survival and growth response to NNK when TxAS was inhibited, affirming the role of TxA(2) receptor in NNK-mediated cell survival and growth. Suppression of cyclic adenosine monophosphate response element binding protein (CREB) activity by its small interference RNA blocked the effect of NNK. Phosphatidylinositol 3-kinase (PI3K)/Akt and extracellular signal-regulated kinase (ERK) also had a positive role. Altogether, our results have revealed that NNK stimulates TxA(2) synthesis and activates its receptor in lung cancer cells. The increased TxA(2) may then activate CREB through PI3K/Akt and extracellular ERK pathways, thereby contributing to the NNK-promoted survival and growth of lung cancer cells.

Black raspberry components inhibit proliferation, induce apoptosis, and modulate gene expression in rat esophageal epithelial cells

We have shown that a diet containing freeze-dried black raspberries (BRB) inhibits the development of chemically induced cancer in the rat esophagus. To provide insights into possible mechanisms by which BRB inhibit esophageal carcinogenesis, we evaluated an ethanol (EtOH) extract of BRB, and two component anthocyanins (cyanidin-3-O-glucoside and cyanidin-3-O-rutinoside) in BRB, for their effects on growth, apoptosis, and gene expression in rat esophageal epithelial cell lines. The EtOH extract and both anthocyanins selectively caused significant growth inhibition and induction of apoptosis in a highly tumorigenic cell line (RE-149 DHD) but not in a weakly tumorigenic line (RE-149). The uptake of anthocyanins from the EtOH extract into RE-149 DHD cells far exceeded their uptake into RE-149 cells, which may have accounted for the selective effects of the extract on growth and apoptosis of RE-149 DHD cells. The growth inhibitory and proapoptotic effects were enhanced by the daily addition of the EtOH extract and the anthocyanins to the medium. Interestingly, the EtOH extract did not alter cyclooxygenase-2 (COX-2) and nitric oxide synthase (i-NOS) expression in RE-149 DHD cells, whereas both anthocyanins downregulated the expressions of these genes. This differential effect may have been related to the relative amounts of anthocyanins in the extract vs. when they were added individually to the medium. We conclude that the selective effects of the EtOH extract on growth and apoptosis of highly tumorigenic rat esophageal epithelial cells in vitro may be due to preferential uptake and retention of its component anthocyanins, and this may also be responsible for the greater inhibitory effects of freeze-dried whole berries on tumor cells in vivo.

Biological activity of celecoxib in the bronchial epithelium of current and former smokers

Non-small cell lung cancer is the primary cause of cancer-related death in Western countries. One important approach taken to address this problem is the development of effective chemoprevention strategies. In this study, we examined whether the cyclooxygenase-2 inhibitor celecoxib, as evidenced by decreased cell proliferation, is biologically active in the bronchial epithelium of current and former smokers. Current or former smokers with at least a 20 pack-year (pack-year = number of packs of cigarettes per day times number of years smoked) smoking history were randomized into one of four treatment arms (3-month intervals of celecoxib then placebo, celecoxib then celecoxib, placebo then celecoxib, or placebo then placebo) and underwent bronchoscopies with biopsies at baseline, 3 months, and 6 months. The 204 patients were primarily (79.4%) current smokers: 81 received either low-dose celecoxib or placebo and 123 received either high-dose celecoxib or placebo. Celecoxib was originally administered orally at 200 mg twice daily and the protocol subsequently increased the dose to 400 mg twice daily. The primary end point was change in Ki-67 labeling (from baseline to 3 months) in bronchial epithelium. No cardiac toxicities were observed in the participants. Although the effect of low-dose treatment was not significant, high-dose celecoxib decreased Ki-67 labeling by 3.85% in former smokers and by 1.10% in current smokers-a significantly greater reduction (P = 0.02) than that seen with placebo after adjusting for metaplasia and smoking status. A 3- to 6-month celecoxib regimen proved safe to administer. Celecoxib (400 mg twice daily) was biologically active in the bronchial epithelium of current and former smokers; additional studies on the efficacy of celecoxib in non-small cell lung cancer chemoprevention may be warranted.

Targeting the eicosanoid pathway in non-small-cell lung cancer

Multiple lines of evidence suggest that cyclooxygenase-2 (COX-2) upregulation is an early event in the development of non-small-cell lung cancer. Preclinical data indicate tumors with upregulation of COX-2 synthesize high levels of prostaglandin E₂ (PGE₂), which in turn are associated with increased production of proangiogenic factors and enhanced metastatic potential. These findings indicate that an increase in COX-2 expression may play a significant role in the development and growth of lung cancers and possibly with the acquisition of an invasive and metastatic phenotype. Consequently, inhibitors of COX-2 are being studied for their chemopreventative and therapeutic effects in individuals at high risk for lung cancer and patients with established cancers.

Contribution of alcohol and tobacco use in gastrointestinal cancer development

Tobacco smoke and alcohol are major risk factors for a variety of cancer sites, including those of the gastrointestinal tract. Tobacco smoke contains a great number of mutagenic and carcinogenic compounds, including polycyclic carbohydrates, nitrosamines, and nicotine, while ethanol per se has only weak carcinogenic potential, but its first metabolite, acetaldehyde, is a mutagen and carcinogen, since it forms stable adducts with DNA. The possibility of proto-oncogene mutation in gastrointestinal mucosa cells may be associated with tobacco smoking-induced cancers through the formation of unfavorable DNA adducts. Individuals with defective DNA repair mechanisms and unfavorable genetic make-up for carcinogen metabolism may be at increased risk for gastrointestinal cancers. Individuals with a high production rate of acetaldehyde from ethanol also have an increased cancer risk when they drink chronically. These include individuals with a genetically determined increased acetaldehyde production due to alcohol dehydrogenase polymorphism and those with a decreased detoxification of acetaldehyde due to acetaldehyde dehydrogenase mutation. In addition, oral bacterial overgrowth due to poor oral hygiene also increases salivary acetaldehyde. Dietary deficiencies such as a lack of folate, riboflavine, and zinc may also contribute to the increase cancer risk in the alcoholic patient. It is of considerable importance that smoking and drinking act synergistically. Smoking increases the acetaldehyde burden following alcohol consumption and drinking enhances the activation of various procarcinogens present in tobacco smoke due to increased metabolic activation by an induced cytochrome P450-2E1-dependent microsomal biotransformation system in the mucosa of the upper digestive tract and the liver.

Cyclooxygenase-2 (cox-2) and the inflammogenesis of cancer

Cohesive scientific evidence from molecular, animal, and human investigations supports the hypothesis that aberrant induction of COX-2 and up-regulation of the prostaglandin cascade play a significant role in carcinogenesis, and reciprocally, blockade of the process has strong potential for cancer prevention and therapy. Supporting evidence includes the following: [1] expression of constitutive COX-2-catalyzed prostaglandin biosynthesis is induced by most cancer-causing agents including tobacco smoke and its components (polycylic aromatic amines, heterocyclic amines, nitrosamines), essential polyunsaturated fatty acids (unconjugated linoleic acid), mitogens, growth factors, proinflammatory cytokines, microbial agents, tumor promoters, and other epigenetic factors, [2] COX-2 expression is a characteristic feature of all premalignant neoplasms, [3] COX-2 expression is a characteristic feature of all malignant neoplasms, and expression intensifies with stage at detection and cancer progression and metastasis, [4] all essential features of carcinogenesis (mutagenesis, mitogenesis, angiogenesis, reduced apoptosis, metastasis, and immunosuppression) are linked to COX-2-driven prostaglandin (PGE-2) biosynthesis, [5] animal studies show that COX-2 up-regulation (in the absence of genetic mutations) is sufficient to stimulate the transformation of normal cells to invasive cancer and metastatic disease, [6] non-selective COX-2 inhibitors, such as aspirin and ibuprofen, reduce the risk of human cancer and precancerous lesions, and [7] selective COX-2 inhibitors, such as celecoxib, reduce the risk of human cancer and precancerous lesions at all anatomic sites thus far investigated. Results confirming that COX-2 blockade is effective for both cancer prevention and therapy have been tempered by observations that some COX2 inhibitors pose a risk to the cardiovascular system, and more studies are needed in order to determine if certain of these drugs can be taken at dosages that prevent cancer without increasing cardiovascular risk. It is emphasized that the "inflammogenesis model of cancer" is not mutually exclusive and may in fact be synergistic with the accumulation of somatic mutations in tumor suppressor genes and oncogenes or epigenetic factors in the development of cancer.

Expression of cyclooxygenase-2 in osteosarcoma of bone

Several studies indicate that cyclooxygenase-2 (COX-2) is overexpressed in human malignancies, where it produces high levels of prostaglandins and contributes to tumor growth. In this study we have analyzed the expression of COX-2 in a series of 48 skeletal osteosarcomas of different subtypes by immunohistochemistry. In addition, we examined the effects of the specific COX-2 inhibitor Celecoxib on the growth of the human osteosarcoma cell line SaOS-2. Immunoreactivity for COX-2 was observed in 39 out of 48 tumors (81.2%), 30 (76.9%) of which showed a moderate or diffuse immunostaining. Considering the group of 42 primary osteosarcomas, COX-2 immunoreactivity was significantly higher in high grade osteosarcomas, where moderate or diffuse expression was detected in 23 out of 32 cases (71.8%), than in low grade osteosarcomas, where moderate or diffuse expression was detected in 2 out of 10 cases (20%) (P = 0.008, Fisher exact test). In addition, low COX-2 expression was always associated with a good response to chemotherapy (5 out of 5 cases), whereas moderate or diffuse COX-2 expression was associated with a good response in 11 out of 20 cases (55%) (P = 0.12, Fisher exact test). In SaOS-2 osteosarcoma cells, which express COX-2, treatment with Celecoxib determined inhibition of cell proliferation and induction of apoptosis. These results indicate that COX-2 is expressed at high levels in high grade osteosarcomas and support the use of COX-2 inhibitors to improve both the tumor response to chemotherapy and the outcome of osteosarcoma patients.

Prodelphinidin B-4 3'-O-gallate, a tea polyphenol, is involved in the inhibition of COX-2 and iNOS via the downregulation of TAK1-NF-kappaB pathway

Much is known about the bioactive properties of green tea flavan-3-ol. However, very little work has been done to determine the properties of proanthocyanidins, another kind of polyphenols in green tea. In this study, we have investigated the anti-inflammatory effect of tea prodelphinidin B-4 3'-O-gallate (PDG) by demonstrating the inhibitory effects on cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in lipopolysaccharide (LPS)-activated murine macrophage RAW264 cells. PDG caused a dose-dependent inhibition of COX-2 and iNOS at both mRNA and protein levels with the attendant decrease of prostaglandin E2 (PGE2) and nitric oxide (NO) production. Molecular data revealed that PDG downregulated NF-kappaB signaling pathway. Electrophoretic mobility shift assay (EMSA) showed that PDG reduced the binding complex of NF-kappaB-DNA in the promoter of COX-2 and iNOS. Immunochemical analysis revealed that PDG suppressed LPS-induced phosphorylation and degradation of IkappaBalpha, and subsequent nuclear translocation of p65. Consequently, PDG suppressed phosphorylation of IkappaB kinase alpha/beta (IKKalpha/beta) and TGF-beta-activated kinase (TAK1). Taken together, our data indicated that PDG is involved in the inhibition of COX-2 and iNOS via the downregulation of TAK1-NF-kappaB pathway, revealing partial molecular basis for the anti-inflammatory properties of tea PDG.

Green tea proanthocyanidins inhibit cyclooxygenase-2 expression in LPS-activated mouse macrophages: molecular mechanisms and structure-activity relationship

The inhibitory effects of green tea proanthocyanidins on cyclooxygenase-2 (COX-2) expression and prostaglandin E(2) (PGE(2)) release were investigated in lipopolysaccharide (LPS)-activated murine macrophage RAW264 cells. Prodelphinidin B2 3,3' di-O-gallate (PDGG) caused a dose-dependent inhibition of COX-2 at both mRNA and protein levels with the attendant release of PGE(2). Molecular evidence revealed that PDGG inhibited the degradation of Ikappa-B, nuclear translocation of p65 and CCAAT/enhancer-binding protein (C/EBP)delta, and phosphorylation of c-Jun, but not CRE-binding protein (CREB), which regulate COX-2 expression. Moreover, PDGG suppressed the activations of mitogen-activated protein kinase (MAPK) including c-Jun NH(2)-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and p38 kinase. The results demonstrated that PDGG suppressed COX-2 expression via blocking MAPK-mediated activation of nuclear factor-kappaB (NF-kappaB), activator protein-1 (AP-1) and C/EBPdelta. Furthermore, studies on structure-activity relationship using five kinds of proanthocyanidins revealed that the galloyl moiety of proanthocyanidins appeared important to their inhibitory actions. Thus, our findings provide the first molecular basis that green tea proanthocyanidins with the galloyl moiety might have anti-inflammatory properties through blocking MAPK-mediated COX-2 expression.

Genotoxic activity and induction of biotransformation enzymes in two human cell lines after treatment by Erika fuel extract

On 12 December 1999, the tanker Erika broke in two parts at about 60km from the Brittany French coasts (Point of Penmarc'h, Sud Finistère, France). About 10,000tonnes of heavy oil fuel were released in the sea. DNA adduct have been detected in fish liver and mussels digestive gland exposed to the Erika oil spill. In order to investigate the mechanism by which Erika fuel extract exhibits genotoxic effects the induction of DNA adducts by an Erika fuel extract have been analysed on two cell lines, human epithelial bronchial cells (WI) and human hepatoma cells. DNA adducts, reflected by a diagonal radioactive zone and individual adducts are detected only in hepatoma cells indicating biotransformation via CYP 1A2 and CYP 1B1. In addition, Erika fuel extract induces some metabolizing enzymes such CYP 1A2, COX2 and 5-LOX, the two later are involved in cancer processes. Formation of leucotrienes B4 (LTB(4)), a mediator playing a role in inflammation, is induced in epithelial bronchial cells. Since inhalation is one of the ways of contamination for human, the above results are important for human health and prevention.

Effect of gamma-linolenic acid and prostaglandins E1 on gamma-radiation and chemical-induced genetic damage to the bone marrow cells of mice

The effect of gamma-linolenic acid (GLA) and prostaglandin E1 (PGE1) on gamma-radiation, diphenylhydantoin (DPH), benzo(a)pyrene (BP), and 4-alpha-phorbol-induced genetic damage to the bone marrow cells of mice, using the sensitive micronucleus (MN) test was investigated. PGE1 and its precursor GLA prevented gamma-radiation, DPH, BP, and 4-alpha-phorbol-induced genetic damage.

Epidemiology of gastric cancer

The incidence and mortality of gastric cancer have fallen dramatically in US and elsewhere over the past several decades. Nonetheless, gastric cancer remains a major public health issue as the fourth most common cancer and the second leading cause of cancer death worldwide. Demographic trends differ by tumor location and histology. While there has been a marked decline in distal, intestinal type gastric cancers, the incidence of proximal, diffuse type adenocarcinomas of the gastric cardia has been increasing, particularly in the Western countries. Incidence by tumor sub-site also varies widely based on geographic location, race, and socio-economic status. Distal gastric cancer predominates in developing countries, among blacks, and in lower socio-economic groups, whereas proximal tumors are more common in developed countries, among whites, and in higher socio-economic classes. Diverging trends in the incidence of gastric cancer by tumor location suggest that they may represent two diseases with different etiologies. The main risk factors for distal gastric cancer include Helicobacter pylori (H pylori) infection and dietary factors, whereas gastroesophageal reflux disease and obesity play important roles in the development of proximal stomach cancer. The purpose of this review is to examine the epidemiology and risk factors of gastric cancer, and to discuss strategies for primary prevention.

Molecular predictors of clinical outcome in patients with head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) involves the upper aerodigestive tract and can destroy the structure and function of organs involved in voice, speech, taste, smell and hearing, as well as vital structures necessary for survival. HNSCC has long been a treatment challenge because of the high rate of recurrences and of advanced disease at the time of diagnosis. Molecular identification of tissue biomarkers in diagnostic biopsy specimens may not only identify patients at risk for developing HNSCC but may also select patients that may benefit from more aggressive treatment modalities. Several biomarkers studied to date such as the proteins p53, cyclin D1, p16, Cox-2 enzyme, epidermal growth factor and vascular endothelial growth factor receptors, matrix metalloproteinases and the Fhit marker for genomic instability could be manipulated for the therapeutic benefit of these patients. This review presents the most updated information on molecular biomarkers with the greatest prognostic potential in HNSCC and discusses some factors that contribute to the controversy concerning their prognostic importance.

Levels of prostaglandin E metabolite, the major urinary metabolite of prostaglandin E2, are increased in smokers

PURPOSE

Increased levels of cyclooxygenase-2 and prostaglandin E2 (PGE2) have been observed in tobacco-related malignancies of the upper aerodigestive tract. Moreover, exposure to tobacco smoke can stimulate the synthesis of PGE2. Recent evidence suggests that urinary PGE metabolite (PGE-M) can be used as an index of systemic PGE2 production. In this study, we investigated whether levels of urinary PGE-M were increased in smokers and in patients with head and neck squamous cell carcinoma (HNSCC).

EXPERIMENTAL DESIGN

Fifty-eight HNSCC cases and 29 age- and gender-matched healthy controls were prospectively enrolled in the study. A detailed smoking history and single void urine specimen were obtained from each participant. Levels of urinary PGE-M were quantified in a blinded fashion using mass spectrometry and compared with smoking history and tumor status.

RESULTS

Adjusted for case-control matching, median urinary PGE-M levels were significantly higher in ever smokers (15.7 ng/mg creatinine) compared with never smokers (9.9 ng/mg creatinine) for the entire study population (n = 87, P = 0.005). Concentrations of urinary PGE-M were nearly doubled in ever smokers (15.2 ng/mg creatinine) versus never smokers (7.8 ng/mg creatinine) among healthy controls (P = 0.001). Higher PGE-M levels were observed in current versus former smokers and in those with greater pack-year exposure. A significant difference in amounts of PGE-M was not observed in patients with HNSCC versus healthy controls.

CONCLUSIONS

Increased levels of urinary PGE-M were observed in smokers. Urinary PGE-M may have use as a noninvasive biomarker of the effects of tobacco smoke exposure.

Molecular pathology of non-small-cell lung cancer

The molecular basis of lung carcinogenesis must be understood more fully and exploited to enhance survival rates of patients suffering from lung cancer. In this review we will discuss the major molecular alterations that occur in lung cancer. Emphasis is placed on alterations that occur early during carcinogenesis since they might be relevant for future screening programs. Finally we will shortly review new approaches that are used to study the molecular pathology of lung cancer and how they can be applied in a clinical setting.

Benzo-[a]-pyrene increases invasion in MDA-MB-231 breast cancer cells via increased COX-II expression and prostaglandin E2 (PGE2) output

Benzo-[a]-pyrene (B[a]P), a carcinogenic component of cigarette smoke, has been shown to increase both COX-II expression and prostaglandin output in vascular smooth muscle and oral epithelial cells. In addition, invasive breast cancer cells have been reported to over express COX-II and PGE(2). Therefore, the objective of this study was to quantify the effect of increasing B[a]P concentrations on COX-II expression, PGE(2) output, and invasion using MDA-MB-231 cells, an invasive estrogen unresponsive breast cancer cell line. B[a]P significantly increased invasion in MDA-MB-231 cells at concentrations greater than 4 x 10(-8) M. Treatment of MDA-MB-231 cells with Vomitoxin (a selective COX-II inducer) enhanced invasion whereas co-treatment with NS398 (a selective COX-II inhibitor) attenuated B[a]P-induced invasion in MDA-MB-231 cells. Immunohistochemical staining and Western blots demonstrated a significant B[a]P treatment-induced increase in both the number of COX-II immunopositive MDA-MB-231 cells and COX-II protein levels. Moreover, B[a]P-treatment induced a profound (46 fold) increase in PGE(2) production by MDA-MB-231 cells. The aryl hydrocarbon receptor (AhR) antagonists resveratrol (RES) and alpha-naphthaflavone (alpha-NF) had no effect on their own, whereas B[a]P-induced invasion was significantly inhibited by co-treatment with RES and alpha-NF. Our data demonstrate that B[a]P-induced changes in invasion are mediated through augmented COX-II expression and PGE(2) production involving an AhR regulated pathway. Moreover, these results suggest a potential role for the AhR signalling pathway in breast cancer invasion.

The aryl hydrocarbon receptor is a regulator of cigarette smoke induction of the cyclooxygenase and prostaglandin pathways in human lung fibroblasts

Cigarette smoking can lead to chronic lung inflammation and lung cancer. Chronic inflammation, associated with expression of cyclooxygenase-2 (COX-2) and prostaglandins, predisposes to malignancy. We recently demonstrated that human lung fibroblasts are activated by cigarette smoke to express COX-2 and prostaglandin E(2) (PGE(2)). Little is known about the mechanism whereby smoke activates human lung fibroblasts to produce proinflammatory mediators. Herein, we report the central role of the aryl hydrocarbon receptor (AHR) in cigarette smoke extract (CSE)-induced COX-2, microsomal PGE(2) synthase (mPGES), and PGE(2) production in human lung fibroblasts. Western blot analysis revealed that primary strains of human lung fibroblasts express AHR and aryl hydrocarbon nuclear translocator protein, supporting the possibility that smoke activates lung fibroblasts through this pathway. Experiments were subsequently performed to determine whether the AHR was activated by CSE. Immunocytochemistry and EMSA analysis revealed that CSE induced nuclear translocation of the AHR in human lung fibroblasts. CSE decreased protein levels of the AHR, consistent with AHR ligand-induced proteosome-mediated degradation. CSE also induced mPGES-1 and COX-2 protein and increased PGE(2) production. Treatment of human fibroblasts with AHR antagonists in the presence of CSE inhibited AHR nuclear translocation as well as COX-2, mPGES-1, and PGE(2) production. These data indicate that the AHR pathway plays an important role in cigarette smoke-mediated COX-2 and PG production in human lung fibroblasts and may contribute to tobacco-associated inflammation and lung disease.

Anthocyanidins inhibit cyclooxygenase-2 expression in LPS-evoked macrophages: structure-activity relationship and molecular mechanisms involved

The effects of anthocyanidins, the aglycon nucleuses of anthocyanins widely occurring in reddish fruits and vegetables, on the expression of cyclooxygenase-2 (COX-2) were investigated in lipopolysaccharide (LPS)-activated murine macrophage RAW264 cells. Of five anthocyanidins, delphinidin and cyanidin inhibited LPS-induced COX-2 expression, but pelargonidin, peonidin and malvidin did not. The structure-activity relationship suggest that the ortho-dihydroxyphenyl structure of anthocyanidins on the B-ring appears to be related with the inhibitory actions. Delphinidin, the most potent inhibitor, caused a dose-dependent inhibition of COX-2 expression at both mRNA and protein levels. Western blotting analysis indicated that delphinidin inhibited the degradation of IkappaB-alpha, nuclear translocation of p65 and CCAAT/enhancer-binding protein (C/EBP)delta and phosphorylation of c-Jun, but not CRE-binding protein (CREB). Moreover, delphinidin suppressed the activations of mitogen-activated protein kinase (MAPK) including c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and p38 kinase. MAPK inhibitors (U0126 for MEK1/2, SB203580 for p38 kinase and SP600125 for JNK) specifically blocked LPS-induced COX-2 expression. Thus, our results demonstrated that LPS-induced COX-2 expression by activating MAPK pathways and delphinidin suppressed COX-2 by blocking MAPK-mediated pathways with the attendant activation of nuclear factor-kappaB (NF-kappaB), activator protein-1 (AP-1) and C/EBPdelta. These findings provide the first molecular basis that anthocyanidins with ortho-dihydroxyphenyl structure may have anti-inflammatory properties through the inhibition of MAPK-mediated COX-2 expression.

Cyclooxygenase-2 in normal, hyperplastic and neoplastic follicular cells of the human thyroid gland

This study was undertaken to investigate cyclooxygenase-2 (COX-2) expression in follicular cells of the human thyroid. COX-2 expression was studied immunohistochemically in a total of 174 samples. COX-2 immunoreactivity was confined to the cell cytoplasm with the nuclei remaining unlabelled. COX-2 expression was observed in five cases (17.2%) of normal follicular cells and in one case (16.6%) of solid cell nests. Follicular carcinoma expressed COX-2 more frequently than follicular adenoma (93.4% vs 21.1%) (p<or=0.001). A higher percentage of cases of papillary microcarcinomas up-regulated COX-2 in comparison with all papillary carcinomas (p<or=0.05). However, we could not establish any relationships among COX-2, patients' ages or lymph node metastases in papillary carcinomas. COX-2 expression was found in 12 (92.3%) poorly differentiated carcinomas and in 13 (92.8%) undifferentiated carcinomas. We found that COX-2 is not always useful as a marker of malignancy. Our results suggest that COX-2 plays a role in progression of all thyroid carcinomas, but in papillary carcinomas, seems more important only in the early stages. COX-2 expression in the undifferentiated carcinoma deserves special consideration due to its prognosis and to the fact that selective COX-2 inhibitors were found to enhance tumour response to radiation in some studies.

Alternative polyadenylation of cyclooxygenase-2

A biologically important human gene, cyclooxygenase-2 (COX-2), has been proposed to be regulated at many levels. While COX-1 is constitutively expressed in cells, COX-2 is inducible and is upregulated in response to many signals. Since increased transcriptional activity accounts for only part of the upregulation of COX-2, we chose to explore other RNA processing mechanisms in the regulation of this gene. We performed a comprehensive bioinformatics survey, the first of its kind known for human COX-2, which revealed that the human COX-2 gene has alternative polyadenylation (proximal and distal sites) and suggested that use of the alternative polyadenylation signals has tissue specificity. We experimentally established this in HepG2 and HT29 cells. We used an in vivo polyadenylation assay to examine the relative strength of the COX-2 proximal and distal polyadenylation signals, and have shown that the proximal polyadenylation signal is much weaker than the distal one. The efficiency of utilization of many suboptimal mammalian polyadenylation signals is affected by sequence elements located upstream of the AAUAAA, known as upstream efficiency elements (USEs). Here, we used in vivo polyadenylation assays in multiple cell lines to demonstrate that the COX-2 proximal polyadenylation signal contains USEs, mutation of the USEs substantially decreased usage of the proximal signal, and that USE spacing relative to the polyadenylation signal was significant. In addition, mutation of the COX-2 proximal polyadenylation signal to a more optimal sequence enhanced polyadenylation efficiency 3.5-fold. Our data suggest for the first time that alternative polyadenylation of COX-2 is an important post-transcriptional regulatory event.

Bioavailability and risk assessment of orally ingested polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) are a family of toxicants that are ubiquitous in the environment. These contaminants generate considerable interest, because some of them are highly carcinogenic in laboratory animals and have been implicated in breast, lung, and colon cancers in humans. These chemicals commonly enter the human body through inhalation of cigarette smoke or consumption of contaminated food. Of these two pathways, dietary intake of PAHs constitutes a major source of exposure in humans. Although many reviews and books on PAHs have been published, factors affecting the accumulation of PAHs in the diet, their absorption following ingestion, and strategies to assess risk from exposure to these hydrocarbons following ingestion have received much less attention. This review, therefore, focuses on concentrations of PAHs in widely consumed dietary ingredients along with gastrointestinal absorption rates in humans. Metabolism and bioavailability of PAHs in animal models and the processes, which influence the disposition of these chemicals, are discussed. The utilitarian value of structure and metabolism in predicting PAH toxicity and carcinogenesis is also emphasized. Finally, based on intake, disposition, and tumorigenesis data, the exposure risk to PAHs from diet, and contaminated soil is presented. This information is expected to provide a framework for refinements in risk assessment of PAHs from a multimedia exposure perspective.

Multifaceted roles of cyclooxygenase-2 in lung cancer

Lung cancer is the leading cause of cancer death in the United States. Although the low 5-year survival rate (under 15%) has changed minimally in the last 25 years, new agents and combinations of agents that target tumor proliferation, invasion, and survival may lead to improvement in patient outcomes. There is evidence that cyclooxygenase-2 (COX-2) is overexpressed in lung cancer and promotes tumor proliferation, invasion, angiogenesis, and resistance to apoptosis. COX-2 inhibitors have been found to inhibit tumor growth in animal models and have demonstrated responses when combined with conventional therapy in phase II clinical trials. Further understanding of the mechanisms involved in COX-2-mediated tumorigenesis and its interaction with other molecules in lung cancer may lead to improved therapeutic strategies for this disease. In addition, delineation of how COX-2-dependent genes modulate the malignant phenotype will provide novel insights in lung cancer pathogenesis.

Cyclooxygenase as a target in lung cancer

Preclinical studies suggest that cyclooxygenase (COX)-2 may be involved in the molecular pathogenesis of some types of lung cancer. Most of the available studies point to its involvement in non-small cell lung cancer. Survival of patients with non-small cell lung cancer expressing high levels of COX-2 is markedly reduced. Treatment of humans with the selective COX-2 inhibitor celecoxib augments the antitumor effects of chemotherapy in patients with non-small cell lung cancer. COX-2 has been shown to regulate some aspects of tumor-associated angiogenesis. Most of the results we have published point to effects on the regulation of vascular endothelial growth factor. However, prostaglandins derived from COX-2 affect other signaling pathways as well, such as the epidermal growth factor and its receptor. Others have recently shown that non-small cell lung cancer exhibits a COX-2 downstream enzyme expression pattern that is altered in lung tumor cells and tumor-supplying vessels. Therefore, COX-2 and prostaglandins may have a major impact on lung tumor progression and tumor-associated inflammation. Clinical trials currently underway are exploring the potential of targeting COX-2 in lung cancer.

Hydroxychavicol modulates benzo[a]pyrene-induced genotoxicity through induction of dihydrodiol dehydrogenase

Areca quid (AQ) chewing and smoking have synergistic potential in the development of oral squamous cell carcinoma (OSCC). In Taiwan, fresh Piper betle inflorescence is uniquely added to AQ, and hydroxychavicol (HC) is the major phenolic component of P. betle inflorescence. This study investigated whether HC modulates cigarette carcinogen benzo[a]pyrene (B[a]P)-mediated toxic effects. Pretreatment of HC and followed by B[a]P challenge resulted in higher cytotoxicity and HPRT gene mutation frequency (P < 0.05). However, this treatment protocol resulted in decreased bulky B[a]P-DNA adduct levels as demonstrated by 32P-postlabeling technique (P < 0.05). Western blotting analysis indicated that HC pretreatment induced the expression of cyclooxygenase-2 (COX-2) and dihydrodiol dehydrogenase (DDH). COX-2 is know to participate in the B[a]P-DNA adduct formation, while DDH has been shown to divert B[a]P-diol to B[a]P-7,8-quinone and the generation of reactive oxygen species (ROS). Using flow cytometry, this study demonstrated the increased production of 8-oxoguanine (P < 0.001). Overall, the results suggest that HC-induced DDH is more important than site-by-site up-regulation of COX-2 in B[a]P-induced cytotoxicity and HPRT gene mutation. Furthermore, DDH-mediated oxidative DNA damage and not B[a]P-DNA adduct formation may be involved in the HC and B[a]P-induced toxic effects.