Cyclooxygenase-2 (cox-2) blockade in the chemoprevention of cancers of the colon, breast, prostate, and lung. Inflammopharmacology. 2009;17:55-67. [PMID: 19340409 DOI: 10.1007/s10787-009-8049-8]

COX-2 and PGE2-dependent immunomodulation in breast cancer

COX-derived prostanoids play multiple roles in inflammation and cancer. This review highlights research examining COX-2 and PGE(2)-dependent regulation of immune cell polarization and function within the tumor microenvironment, particularly as it pertains to breast cancer. Appreciating PGE(2)-mediated immunomodulation is important in understanding how tumors evade immune surveillance by re-educating infiltrating inflammatory and immune cells to support tumorigenesis. Elucidation of the multiple and complex influences exerted by tumor stromal components may lead to targeted therapies in breast and other cancers that restrain microenvironmental permissiveness and maintain natural defenses against malignancies.

Cyclooxygenase-2 expression in oral tongue squamous cell carcinoma

BACKGROUND

Cyclooxygenase-2 expression is associated with unfavorable outcome in various cancers, and evidence is accumulating that carcinogenesis possibly evolves from intracellular changes in response to induction of this enzyme. Today selective cyclooxygenase-2 inhibitors are being studied and used as complement in cancer treatment. This study examined the prognostic value of cyclooxygenase-2 expression in oral tongue squamous cell carcinoma (OTSCC).

METHODS

Expression of cyclooxygenase-2 was determined in biopsies from 76 stage matched patients with OTSCC by immunohistochemistry between January 2000 and December 2004 in Stockholm, Sweden. Additionally, twelve samples taken after pre-operative radiotherapy were investigated.

RESULTS

All OTSCC specimen expressed cyclooxygenase-2 by immunostaining. The cyclooxygenase-2 staining intensity increased significantly with more advanced stage (P=0.020). Fifty percent of the surgical specimen showed a decrease in immunostaining post-radiation (P=0.031). No association was found with survival.

CONCLUSION

Cyclooxygenase-2 expression has limited prognostic value in OTSCC.

Expression of cyclooxygenase-1 and cyclooxygenase-2 in normal and pathological human oral mucosa

Cyclooxigenase (COX) is the rate-limiting enzyme for the conversion of arachidonic acid (AA) to prostaglandins (PGs). Two isoforms of COX have been identified: COX-1 is constitutively expressed in many cells and is involved in cell homeostasis, angiogenesis and cell-cell signalling; COX-2 is not expressed in normal condition however it is strongly expressed in inflammation. The oral cavity is constantly exposed to physical and chemical trauma that could lead to mucosal reactions such as hyperplasia, dysplasia and cancer. Early diagnosis is the most important issue to address for a positive outcome of oral cancer; therefore it would be useful to identify molecular markers whose expression is associated with the various stages of oral cancer progression. Since COX enzyme has been involved, with different mechanisms, in the development and progression of malignancies we decided to investigate the expression and localization of COX-1 and COX-2 in normal human oral mucosa and three different pathologies (hyperplasia, dysplasia and carcinoma) by immunohistochemistry and RT-PCR. COX-1 mRNA and protein have been detected already in normal oral mucosa and their expression progressively increases from normal samples towards hyperplasia, dysplasia and finally carcinoma. On the contrary, COX-2 is not expressed in the normal tissue, starts to be expressed in hyperplasia, reaches the maximum activation in dysplasia and then starts to be downregulated in carcinoma.

Integrin α3β1 as a breast cancer target

INTRODUCTION

Integrin receptors for cell adhesion to the extracellular matrix have important roles in all stages of cancer progression and metastasis. Since the integrin family was discovered in the early 1980's, many studies have identified critical adhesion and signaling functions for integrins expressed on tumor cells, endothelial cells and other cell types of the tumor microenvironment, in controlling proliferation, survival, migration and angiogenesis. In recent years, the laminin-binding integrin α3β1 has emerged as a potentially promising anti-cancer target on breast cancer cells.

AREAS COVERED

Studies from the past decade that implicate integrins as promising anti-cancer targets and the development of integrin antagonists as anti-cancer therapeutics. Recent preclinical studies that have identified the laminin-binding integrin α3β1 as an appealing anti-cancer target and the knowledge gaps that must be closed to fully exploit this integrin as a therapeutic target for breast cancer.

EXPERT OPINION

Although the tumor-promoting functions of α3β1 implicate this integrin as a promising therapeutic target on breast cancer cells, successful exploitation of this integrin as an anti-cancer target will require a better understanding of the molecular mechanisms whereby it regulates specific tumor cell behaviors and the identification of the most appropriate α3β1 functions to antagonize on breast cancer cells.

Chemoprevention--history and general principles

Our current understanding of tumourigenesis suggests that cancer develops as a series of cumulative genetic and epigenetic derangements across time culminating in a clone of cells differing from its population of origin in terms of cellular identity, growth control, and its contextual relationship to its environment. Our increasing knowledge of the timing, sequence, frequency, and specific implications of these changes provides unique opportunities for earlier identification of aberrations and preventive interventions. Here we discuss the fundamentals of cancer prevention including the targets, cohorts, agents, endpoints, mechanistic biomarkers, designs, and strategies employed in preventive drug development. There have been many notable successes in this field such as the identification and development of tamoxifen and raloxifene for breast cancer risk reduction, instillational BCG and valrubicin for treatment of preinvasive bladder cancer, and a variety of topical and systemic agents that effectively treat preinvasive neoplastic lesions of the skin. A variety of null or negative developmental endeavours have occurred as well, including trials of beta-carotene for lung cancer prevention, nutritional modifications for colorectal adenoma prevention, and most recently, selenium and alpha-tocopherol for prostate cancer prevention. A third category of prevention trials can be summarized as investigationally successful, but not achieving regulatory success. The development of finasteride and dutasteride for prostate cancer prevention, and celecoxib for colorectal neoplasia prevention fall into this category. In less than four decades, cancer chemoprevention has transformed from a concept to an achievable reality.

Inhibition of lipopolysaccharide-induced cyclooxygenase-2 and inducible nitric oxide synthase expression by 4-[(2'-O-acetyl-α-L-rhamnosyloxy)benzyl]isothiocyanate from Moringa oleifera

Moringa oleifera Lamarck is commonly consumed for nutritional or medicinal properties. We recently reported the isolation and structure elucidation of novel bioactive phenolic glycosides, including 4-[(2'-O-acetyl-α-L-rhamnosyloxy)benzyl]isothiocyanate (RBITC), which was found to suppress inducible nitric oxide synthase (iNOS) expression and nitric oxide (NO) production in lipopolysaccharide-stimulated RAW 264.7 mouse macrophage cells. Inhibitors of proteins such as cyclooxygenase-2 (COX-2) and iNOS are potential antiinflammatory and cancer chemopreventive agents. The inhibitory activity of RBITC on NO production (IC(50) = 0.96 ± 0.23 μM) was greater than that mediated by other well-known isothiocyanates such as sulforaphane (IC(50) = 2.86 ± 0.39 μM) and benzyl isothiocyanate (IC(50) = 2.08 ± 0.28 μM). RBITC inhibited expression of COX-2 and iNOS at both the protein and mRNA levels. Major upstream signaling pathways involved mitogen-activated protein kinases and nuclear factor-κB (NF-κB). RBITC inhibited phosphorylation of extracellular signal-regulated kinase and stress-activated protein kinase, as well as ubiquitin-dependent degradation of inhibitor κBα (IκBα). In accordance with IκBα degradation, nuclear accumulation of NF-κB and subsequent binding to NF-κB cis-acting element was attenuated by treatment with RBITC. These data suggest RBITC should be included in the dietary armamentarium of isothiocyanates potentially capable of mediating antiinflammatory or cancer chemopreventive activity.

Deletion of cyclooxygenase 2 in mouse mammary epithelial cells delays breast cancer onset through augmentation of type 1 immune responses in tumors

Inhibition of cyclooxygenase (COX) 2, which is associated with >40% of breast cancers, decreases the risk of tumorigenesis and breast cancer recurrence. To study the role of COX-2 in breast cancer, we engineered mice that lack selectively mammary epithelial cell (MEC) COX-2 (COX-2 KO(MEC)). Compared with wild type (WT), MEC from COX-2 KO(MEC) mice expressed >90% less COX-2 messenger RNA (mRNA) and protein and produced 90% less of the dominant pro-oncogenic COX-2 product, prostaglandin (PG) E(2). We confirmed COX-2 as the principle source of PGE(2) in MEC treated with selective COX-2 and COX-1 inhibitors. Tumors were induced in mice using medroxyprogesterone acetate and 7,12-dimethylbenz[a]anthracene. Breast cancer onset was significantly delayed in COX-2 KO(MEC) compared with WT (P = 0.03), equivalent to the delay following systemic COX-2 inhibition with rofecoxib. Compared with WT, COX-2 KO(MEC) tumors showed increased mRNA for Caspase-3, Ki-67 and common markers for leukocytes (CD45) and macrophages (F4/80). Analysis of multiple markers/cytokines, namely CD86, inducible nitric oxide synthase (iNOS), interleukin-6, tumor necrosis factor α (TNFα) and Tim-3 indicated a shift toward antitumorigenic type 1 immune responses in COX-2 KO(MEC) tumors. Immunohistochemical analysis confirmed elevated expression of CD45, F4/80 and CD86 in COX-2 KO(MEC) tumors. Concordant with a role for COX-2 in restraining M1 macrophage polarization, CD86 and TNFα expression were offset by exogenous PGE(2) in bone marrow-derived macrophages polarized in vitro to the M1 phenotype. Our data reveal the importance of epithelial COX-2 in tumor promotion and indicate that deletion of epithelial COX-2 may skew tumor immunity toward type 1 responses, coincident with delayed tumor development.

A systematic review to establish the frequency of cyclooxygenase-2 expression in normal breast epithelium, ductal carcinoma in situ, microinvasive carcinoma of the breast and invasive breast cancer

Background:

Epidemiological studies have suggested a protective effect of cyclooxygenase (COX)-inhibiting non-steroidal anti-inflammatory drugs in breast cancer risk and disease progression. We performed a systematic review to evaluate the frequency of COX-2 expression in normal breast epithelium, ductal carcinoma in situ of breast (DCIS), DCIS-adjoining invasive breast cancer, microinvasive carcinoma of the breast (MICB) and invasive breast cancer.

Methods:

Literature searches were carried out on MEDLINE, EMBASE and Web of Science from their commencement until September 2010. Primary studies examining COX-2 expression by immunohistochemistry methodology were included. Meta-analyses were carried out using random effects models for individual study estimates of COX-2 expression and pooled to give an overall estimate.

Results:

The pooled prevalences (95% confidence intervals) of COX-2 expressions were 53% (44–61) in DCIS studies and 42% (36–49) in the invasive breast cancer studies. There were too few studies involving normal breast epithelium, DCIS-adjoining invasive breast cancer and MICB to conduct meta-analyses.

Conclusion:

The findings from our meta-analyses have shown similar COX-2 expression in DCIS and invasive breast cancer. This may suggest the involvement of COX-2 in early carcinogenesis. Further studies of COX-2 expression in DCIS are required to investigate the use of COX-2 as a potential drug target for prevention of disease progression in DCIS.

Regression of prostate tumors upon combination of hormone ablation therapy and celecoxib in vivo

BACKGROUND

Hormonal ablation is the standard of treatment for advanced androgen-dependent prostate cancer. Although tumor regression is usually achieved at first, the cancer inevitably evolves toward androgen-independence, in part because of the development of mechanisms of resistance and in part because at the tissue level androgen withdrawal is not fully attained. Current research efforts are focused on new therapeutic strategies that will increase the effectiveness of androgen withdrawal and delay recurrence. We used a syngeneic pseudo-orthotropic mouse model of prostate cancer to test the efficacy of combining androgen withdrawal with FDA-approved COX-2 inhibitor celecoxib.

METHODS

GFP-tagged TRAMP-C2 cells were co-implanted with prostate tissue in the dorsal chamber model and tumors were allowed to establish and vascularize. Tumor growth and angiogenesis were monitored in real-time using fluorescent intravital microscopy (IVM). Androgen withdrawal in mice was achieved using surgical castration or chemical hormonal ablation, alone or in combination with celecoxib (15 mg/kg, twice daily).

RESULTS

Celecoxib alone decreased the growth of prostate tumors mostly by inducing mitotic failure, which resulted in increased apoptosis. Surprisingly, celecoxib did not possess significant angiostatic activity. Surgical or chemical castration prevented the growth of prostate tumors and this, on the other hand, was associated with disruption of the tumor vasculature. Finally, androgen withdrawal combined with celecoxib caused tumor regression through decreased angiogenesis and increased mitosis arrest and apoptosis.

CONCLUSION

Celecoxib, a relatively safe COX-2-selective anti-inflammatory drug, significantly increases the efficacy of androgen withdrawal in vivo and warrants further investigation as a complement therapy for advanced prostate cancer.

Global gene expression profiling of a population exposed to a range of benzene levels

BACKGROUND

Benzene, an established cause of acute myeloid leukemia (AML), may also cause one or more lymphoid malignancies in humans. Previously, we identified genes and pathways associated with exposure to high (> 10 ppm) levels of benzene through transcriptomic analyses of blood cells from a small number of occupationally exposed workers.

OBJECTIVES

The goals of this study were to identify potential biomarkers of benzene exposure and/or early effects and to elucidate mechanisms relevant to risk of hematotoxicity, leukemia, and lymphoid malignancy in occupationally exposed individuals, many of whom were exposed to benzene levels < 1 ppm, the current U.S. occupational standard.

METHODS

We analyzed global gene expression in the peripheral blood mononuclear cells of 125 workers exposed to benzene levels ranging from < 1 ppm to > 10 ppm. Study design and analysis with a mixed-effects model minimized potential confounding and experimental variability.

RESULTS

We observed highly significant widespread perturbation of gene expression at all exposure levels. The AML pathway was among the pathways most significantly associated with benzene exposure. Immune response pathways were associated with most exposure levels, potentially providing biological plausibility for an association between lymphoma and benzene exposure. We identified a 16-gene expression signature associated with all levels of benzene exposure.

CONCLUSIONS

Our findings suggest that chronic benzene exposure, even at levels below the current U.S. occupational standard, perturbs many genes, biological processes, and pathways. These findings expand our understanding of the mechanisms by which benzene may induce hematotoxicity, leukemia, and lymphoma and reveal relevant potential biomarkers associated with a range of exposures.

Chemical 'Jekyll and Hyde's: small-molecule inhibitors of developmental signaling pathways

Small molecules that perturb developmental signaling pathways can have devastating effects on embryonic patterning, as evidenced by the chemically induced onset of cyclopic lambs and children with severely shortened limbs during the 1950s. Recent studies, however, have revealed critical roles for these pathways in human disorders and diseases, spurring the re-examination of these compounds as new targeted therapies. In this tutorial review, we describe four case studies of teratogenic compounds, including inhibitors of the Hedgehog (Hh), Wnt, and bone morphogenetic protein (BMP) pathways. We discuss how these teratogens were discovered, their mechanisms of action, their utility as molecular probes, and their potential as therapeutic agents. We also consider current challenges in the field and possible directions for future research.

Chronic obstructive pulmonary disease and lung cancer: new molecular insights

Both chronic obstructive pulmonary disease (COPD) and lung cancer are major causes of death worldwide. In most cases this reflects cigarette smoke exposure which is able to induce an inflammatory response in the airways of smokers. Indeed, COPD is characterized by lower airway inflammation, and importantly, the presence of COPD is by far the greatest risk factor for lung cancer amongst smokers. Cigarette smoke induces the release of many inflammatory mediators and growth factors including TGF-β, EGFR, IL-1, IL-8 and G-CSF through oxidative stress pathways and this inflammation may persist for decades after smoking cessation. Mucus production is also increased by these inflammatory mediators, further linking airway inflammation to an important mechanism of lung cancer. A greater understanding of the molecular and cellular pathobiology that distinguishes smokers with lung cancer from smokers with and without COPD is needed to unravel the complex molecular interactions between COPD and lung cancer. By understanding the common signalling pathways involved in COPD and lung cancer the hope is that treatments will be developed that not only treat the underlying disease process in COPD, but also reduce the currently high risk of developing lung cancer in these patients.

Cyclooxygenase 2 promotes parathyroid hyperplasia in ESRD

Hyperplasia of the PTG underlies the secondary hyperparathyroidism (SHPT) observed in CKD, but the mechanism underlying this hyperplasia is incompletely understood. Because aberrant cyclooxygenase 2 (COX2) expression promotes epithelial cell proliferation, we examined the effects of COX2 on the parathyroid gland in uremia. In patients with ESRD who underwent parathyroidectomy, clusters of cells within the parathyroid glands had increased COX2 expression. Some COX2-positive cells exhibited two nuclei, consistent with proliferation. Furthermore, nearly 78% of COX2-positive cells expressed proliferating cell nuclear antigen (PCNA). In the 5/6-nephrectomy rat model, rats fed a high-phosphate diet had significantly higher serum PTH levels and larger parathyroid glands than sham-operated rats. Compared with controls, the parathyroid glands of uremic rats exhibited more PCNA-positive cells and greater COX2 expression in the chief cells. Treatment with COX2 inhibitor celecoxib significantly reduced PCNA expression, attenuated serum PTH levels, and reduced the size of the glands. In conclusion, COX2 promotes the pathogenesis of hyperparathyroidism in ESRD, suggesting that inhibiting the COX2 pathway could be a potential therapeutic target.

Animal products, diseases and drugs: a plea for better integration between agricultural sciences, human nutrition and human pharmacology

Eicosanoids are major players in the pathogenesis of several common diseases, with either overproduction or imbalance (e.g. between thromboxanes and prostacyclins) often leading to worsening of disease symptoms. Both the total rate of eicosanoid production and the balance between eicosanoids with opposite effects are strongly dependent on dietary factors, such as the daily intakes of various eicosanoid precursor fatty acids, and also on the intakes of several antioxidant nutrients including selenium and sulphur amino acids. Even though the underlying biochemical mechanisms have been thoroughly studied for more than 30 years, neither the agricultural sector nor medical practitioners have shown much interest in making practical use of the abundant high-quality research data now available. In this article, we discuss some specific examples of the interactions between diet and drugs in the pathogenesis and therapy of various common diseases. We also discuss, using common pain conditions and cancer as specific examples, how a better integration between agricultural science, nutrition and pharmacology could lead to improved treatment for important diseases (with improved overall therapeutic effect at the same time as negative side effects and therapy costs can be strongly reduced). It is shown how an unnaturally high omega-6/omega-3 fatty acid concentration ratio in meat, offal and eggs (because the omega-6/omega-3 ratio of the animal diet is unnaturally high) directly leads to exacerbation of pain conditions, cardiovascular disease and probably most cancers. It should be technologically easy and fairly inexpensive to produce poultry and pork meat with much more long-chain omega-3 fatty acids and less arachidonic acid than now, at the same time as they could also have a similar selenium concentration as is common in marine fish. The health economic benefits of such products for society as a whole must be expected vastly to outweigh the direct costs for the farming sector.

Platelet-activating factor and metastasis: calcium-independent phospholipase A2β deficiency protects against breast cancer metastasis to the lung

We determined the contribution of calcium-independent phospholipase A(2)β (iPLA(2)β) to lung metastasis development following breast cancer injection into wild-type (WT) and iPLA(2)β-knockout (iPLA(2)β-KO) mice. WT and iPLA(2)β-KO mice were injected in the mammary pad with 200,000 E0771 breast cancer cells. There was no difference in primary tumor size between WT and iPLA(2)β-KO mice at 27 days postinjection. However, we observed an 11-fold greater number of breast cancer cells in the lungs of WT mice compared with iPLA(2)β-KO animals (P < 0.05). Isolated WT lung endothelial cells demonstrated a significant increase in platelet-activating factor (PAF) production when stimulated with thrombin [1 IU/ml, 10 min, 4,330 ± 555 vs. 15,227 ± 1,043 disintegrations per minute (dpm), P < 0.01] or TNF-α (10 ng/ml, 2 h, 16,532 ± 538 dpm, P < 0.01). Adherence of E0771 cells to WT endothelial cells was increased by thrombin (4.8 ± 0.3% vs. 70.9 ± 6.3, P < 0.01) or TNF-α (60.5 ± 4.3, P < 0.01). These responses were blocked by pretreatment with the iPLA(2)β-selective inhibitor (S)-bromoenol lactone and absent in lung endothelial cells from iPLA(2)β-KO mice. These data indicate that endothelial cell iPLA(2)β is responsible for PAF production and adherence of E0771 cells and may play a role in cancer cell migration to distal locations.

Cyclooxygenase-2, p53 and glucose transporter-1 as predictors of malignancy in the development of gallbladder carcinomas

Gallbladder carcinoma is the fifth most common malignancy of the gastrointestinal tract. The absolute characteristics of the disease are the high mortality rate due to the late discovery of a tumor and the low therapeutic possibilities except by surgical intervention. In oncology we can predict the outcome of the disease with a combination of classical standard clinico/pathological parameters (stage of the tumors, differentiation) and the intrinsic genetic and biochemical properties of the tumor. Such intrinzic properties of the tumors that are connected with the outcome of the disease are the denominators (markers). The author searched extensively for the expression and influence of 3 markers included in chronic inflammation and early carcinogenesis, cell cycle regulation and tissue hypoxia: cyclooxygenase-2 (COX-2), p53 gene and glucose transporter-1 protein (GLUT-1). The author discusses their possible role in the development as well as fighting this disease, if specific medications targeting them were available.

Cyclooxygenase-2 in oncogenesis

Compelling experimental and clinical evidence supports the notion that cyclooxygenase-2, the inducible isoform of cyclooxygenase, plays a crucial role in oncogenesis. Clinical and epidemiological data indicate that aberrant regulation of cyclooxygenase-2 in certain solid tumors and hematological malignancies is associated with adverse clinical outcome. Moreover, findings extrapolated from experimental studies in cultured tumor cells and animal tumor models indicate that cyclooxygenase-2 critically influences all stages of tumor development from tumor initiation to tumor progression. Cyclooxygenase-2 elicits cell-autonomous effects on tumor cells resulting in stimulation of growth, increased cell survival, enhanced tumor cell invasiveness, stimulation of neovascularization, and tumor evasion from the host immune system. Additionally, the oncogenic effects of cyclooxygenase-2 stem from its unique ability to impact tumor cell surroundings and create a proinflammatory environment conducive for tumor development, growth and progression. The initial enthusiasm generated by the availability of cyclooxygenase-2 selective inhibitors for cancer prevention and therapy has been lessened by the severe cardiovascular adverse side effects associated with their long-term use, as well as by the mixed results of recent clinical trials evaluating the efficacy of cyclooxygenase-2 inhibitors in adjuvant chemotherapy. Therefore, our ability to efficiently target the oncogenic effects of cyclooxygenase-2 for therapeutic and preventive purposes strictly depends on a better understanding of the spatial and temporal aspects of its activation in tumor cells along with a clearer elucidation of the signaling networks whereby cyclooxygenase-2 affects tumor cells and their interactions with the tumor microenvironment. This knowledge has the potential of leading to the identification of novel cyclooxygenase-2-dependent molecular and signaling networks that can be exploited to improve cancer prevention and therapy.

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.

The value of MG7-Ag and COX-2 for predicting malignancy in gastric precancerous lesions

Here we aimed to first investigate the clinical value of combined detection of MG7-Ag and COX-2 (cyclo-oxygenase 2) in prediction of advances in gastric precancerous lesions. Immunohistochemical analysis was used to examine the expression of MG7-Ag and COX-2 in 396 cases of patients with gastric precancerous lesions, including 66 cases of atrophic gastritis, 106 cases of intestinal metaplasia, 174 cases of low-moderate-grade dysplasia and 50 cases of high-grade dysplasia. The relation of MG7-Ag and COX-2 staining with various clinicopathological features was analysed by follow-up study. The positive rates of MG7-Ag and COX-2 were increased gradually from atrophic gastritis (21.2%, 28.8%), intestinal metaplasia (36.8%, 44.3%), low-moderate-grade dysplasia (51.4%, 58.6%) to high-grade dysplasia (72%, 80%). Double positive staining of MG7-Ag and COX-2 in gastric precancerous lesions had an increased risk of precancerous progression over 22 times, compared with negative ones. However, the expression of MG7-Ag and COX-2 was not significantly correlated with age and gender of patients. MG7-Ag and COX-2 might play an important role in the process of carcinogenesis and progression of gastric cancer. Combined detection of MG7-Ag and COX-2 was of value of predicting early gastric cancer from precancerous lesions.

Specialty supplements and breast cancer risk in the VITamins And Lifestyle (VITAL) Cohort

BACKGROUND

Use of nonvitamin, nonmineral "specialty" supplements has increased substantially over recent decades. Several supplements may have anti-inflammatory or anticancer properties. Additionally, supplements taken for symptoms of menopause have been associated with reduced risk of breast cancer in two case-control studies. However, there have been no prospective studies of the association between the long-term use of these supplements and breast cancer risk.

METHODS

Participants were female members of the VITamins And Lifestyle (VITAL) Cohort. Postmenopausal women, ages 50 to 76 years, who were residents of western Washington State, completed a 24-page baseline questionnaire in 2000 to 2002 (n = 35,016). Participants were queried on their recency (current versus past), frequency (days/week), and duration (years) of specialty supplement use. Incident invasive breast cancers (n = 880) from 2000 to 2007 were obtained from the Surveillance, Epidemiology, and End Results registry. Multivariable-adjusted hazards ratios (HR) and 95% confidence intervals (95% CI) were estimated by Cox proportional hazards models.

RESULTS

Current use of fish oil was associated with reduced risk of breast cancer (HR, 0.68; 95% CI, 0.50-0.92). Ten-year average use was suggestive of reduced risk (P trend = 0.09). These results held for ductal but not lobular cancers. The remaining specialty supplements were not associated with breast cancer risk: Specifically, use of supplements sometimes taken for menopausal symptoms (black cohosh, dong quai, soy, or St. John's wort) was not associated with risk.

CONCLUSIONS

Fish oil may be inversely associated with breast cancer risk.

IMPACT

Fish oil is a potential candidate for chemoprevention studies. Until that time, it is not recommended for individual use for breast cancer prevention.

Association between expression of embryonic lethal abnormal vision-like protein HuR and cyclooxygenase-2 in oral squamous cell carcinoma

BACKGROUND

Increased cytoplasmic HuR expression has been noted in several cancer types, where it may contribute to the increased cyclooxygenase-2 (COX-2) expression observed during tumorigenesis and metastasis.

METHODS

To assess the correlation between COX-2 and HuR in oral squamous cell carcinoma (OSCC), the expression patterns of HuR and COX-2 were assessed via immunohistochemistry analyses of 103 OSCC samples.

RESULTS

Cytoplasmic HuR expression was significantly associated with COX-2 expression (p < .025) and lymph node metastasis (p < .050) and distant metastasis (p < .025). In multivariate analysis, cytoplasmic HuR expression was identified as an independent prognostic parameter for reduced overall survival. The inhibition of HuR expression by siRNA or leptomycin B (LMB) caused a reduction in the inducibility of COX-2 in oral cancer cells.

CONCLUSION

Our results indicate that the cytoplasmic expression of HuR is associated with COX-2 expression in OSCCs and HuR can regulate COX-2 expression in oral cancer cell lines.

Anti-cancer effects of celecoxib on nasopharyngeal carcinoma HNE-1 cells expressing COX-2 oncoprotein

Celecoxib is a selective cyclooxygenase-2 (COX-2) inhibitor with antitumor and antiangiogenic activities. To investigate the effects of celecoxib on nasopharyngeal carcinoma (NPC), HNE-1 cells were treated with celecoxib at various concentrations. MTT assay, migration assay and invasion assay were performed to observe the inhibitory activity of celecoxib on HNE-1 cells. Additionally, VEGF-A expression and radiation survival of NPC cell were also examined after treatment with celecoxib. Celecoxib treatment presented an anti-proliferation function in a time and dose-dependent manner on HNE-1 cells which highly express COX-2 protein. Celecoxib also displayed an obvious inhibitory activity on invasive capacity of NPC cells. Moreover, the celecoxib's effects to suppress VEGF-A expression and enhance radiosensitivity were detected in HNE-1 cells. These findings implicate that application of celecoxib may be an effective strategy for NPC therapy.

Sprouty-2 controls c-Met expression and metastatic potential of colon cancer cells: sprouty/c-Met upregulation in human colonic adenocarcinomas

Sprouty negatively regulates receptor tyrosine kinase signals by inhibiting Ras/ERK pathways. Sprouty is down-regulated in breast, prostate and liver cancers and appears to function as a tumor suppressor. The role of Sprouty in colonic neoplasia, however, has not been investigated. Sprouty-2 protein and mRNA transcripts were significantly up-regulated in human colonic adenocarcinomas. Strikingly, the c-Met receptor was also upregulated in tumors with increased sprouty-2. To delineate a potential causal relationship between sprouty-2 and c-Met, K-ras mutant HCT-116 colon cancer cells were transduced with purified TAT-sprouty-2 protein or stably transfected with full-length human sprouty-2 gene. Sprouty-2 up-regulation significantly increased cell proliferation by accelerating cell cycle transition. Sprouty-2 transfectants demonstrated strong up-regulation of c-Met protein and mRNA transcripts and hepatocyte growth factor stimulated ERK and Akt phosphorylation and enhanced cell migration and invasion. In contrast, knockdown of c-Met by siRNA significantly decreased cell proliferation, migration and invasion in sprouty-2 transfectants. Further, knockdown of sprouty-2 by siRNA in parental HT-29 and LS-174T colon cancer cells also decreased cell invasion. Sprouty-2 transfectants formed significantly larger tumor xenografts and demonstrated increased proliferation and angiogenesis and suppressed apoptosis. Sprouty-2 tumors metastasized to liver from cecal orthotopic implants suggesting sprouty-2 might also enhance metastatic signals. Thus in colon cancer sprouty functions as an oncogene and its effects are mediated in part by c-Met up-regulation.

Nimesulide, a selective cyclooxygenase-2 inhibitor, inhibits the growth of esophageal carcinoma in vivo by modulating PPARγ signal transduction pathway

AIM: To detect the expression of cyclooxygenase-2 (COX-2) and peroxisome proliferator-activated receptor γ (PPARγ) in human esophageal carcinoma, to investigate the inhibitory effects of nimesulide on tumor growth in esophageal carcinoma xenografts in nude mice, and to explore potential mechanisms involved.

METHODS: The expression of PPARγ and COX-2 in 18 normal esophageal epithelial specimens and 59 esophageal squamous cell carcinoma (ESCC) specimens were examined by immunohistochemistry. A nude mouse model bearing Eca-109 cell xenografts was established. The mice were divided randomly into control group and nimesulide group [treated with nimesulide at a dose of 20 mg/(kg•d) for 4 wk]. The tumor volume and reduced rate of tumor growth were calculated according to the length and width of xenograft tumors. Cell apoptosis was detected by flow cytometry. The expression of COX-2 and PPARγ mRNAs and proteins was detected by RT-PCR and immunohistochemistry, respectively.

RESULTS: The immunohistochemical score of PPARγ was significantly lower in ESCC than in normal esophageal epithelium (2.88 ± 2.23 vs 6.29 ± 2.17, P < 0.05), while that of COX-2 was significantly higher in ESCC than in normal esophageal epithelium (2.12 ± 1.77 vs 0.82 ± 0.46, P < 0.05). The immunohistochemical score of PPARγ decreased as tumor pathological grade increased. The immunohistochemical score of PPARγ was closely related to tumor differentiation degree (P < 0.05). The expression level of COX-2 was significantly higher in well and moderately differentiated ESCC than in poorly differentiated ESCC (P < 0.05). Nimesulide significantly inhibited tumor growth in esophageal carcinoma xenografts when compared with the control group (tumor volume: 807.68 mm3 ± 217.76 mm3 vs 2116.77 mm3 ± 362.47 mm3; tumor weight: 0.81 g ± 0.21 g vs 1.45 g ± 0.39 g; both P < 0.05), and the reduced rate of tumor growth was 44.14% ± 6.3%. Nimesulide treatment increased the apoptosis rate from 15.86% ± 2.57% to 32.21% ± 5.98%. COX-2 expression was down-regulated, and PPARγ expression up-regulated in the nimesulide group when compared with the control group. A negative correlation was noted between the expression of COX-2 and PPARγ.

CONCLUSION: Down-regulation of PPARγ expression and up-regulation of COX-2 expression are related to the carcinogenesis of ESCC. Nimesulide inhibits tumor growth and induces apoptosis in esophageal carcinoma xenografts possibly by down-regulating COX-2 expression and up-regulating PPARγ expression.

The Role of Non-Steroidal Anti-Inflammatory Drugs in the Chemoprevention of Breast Cancer

Epidemiological evidence suggests that non-steroidal anti-inflammatory drugs (NSAIDs) which act as cyclooxygenase (COX-2) inhibitors may reduce breast cancer incidence by up to 20%. These agents are often taken for pain relief by older women with osteoarthritis. Age is the major risk factor for breast cancer in women with 50% cases being diagnosed in those aged >65 years. NSAIDs reduce serum estradiol by 17% in post-menopausal women and since most of these who develop breast cancers have estrogen receptor positive tumours; this suggests a possible preventative role. Careful use of these agents could provide a strategy for both relief of symptoms of osteoarthritis and also breast cancer prevention. Instead of conducting a randomised trial, proof of efficacy could be from an adequately powered cohort study within the breast screening programme.

Role of inflammation and oxidative stress mediators in gliomas

Gliomas are the most common primary brain tumors of the central nervous system. Despite relevant progress in conventional treatments, the prognosis of such tumors remains almost invariably dismal. The genesis of gliomas is a complex, multistep process that includes cellular neoplastic transformation, resistance to apoptosis, loss of control of the cell cycle, angiogenesis, and the acquisition of invasive properties. Among a number of different biomolecular events, the existence of molecular connections between inflammation and oxidative stress pathways and the development of this cancer has been demonstrated. In particular, the tumor microenvironment, which is largely orchestrated by inflammatory molecules, is an indispensable participant in the neoplastic process, promoting proliferation, survival and migration of such tumors. Proinflammatory cytokines, such as tumor necrosis factor-alpha, interleukin-1beta, and interferon-gamma, as well as chemokines and prostaglandins, are synthesized by resident brain cells and lymphocytes invading the affected brain tissue. Key mediators of cancer progression include nuclear factor-kappaB, reactive oxygen and nitrogen species, and specific microRNAs. The collective activity of these mediators is largely responsible for a pro-tumorigenic response through changes in cell proliferation, cell death, cellular senescence, DNA mutation rates, DNA methylation and angiogenesis. We provide a general overview of the connection between specific inflammation and oxidative stress pathway molecules and gliomas. The elucidation of specific effects and interactions of these factors may provide the opportunity for the identification of new target molecules leading to improved diagnosis and treatment.

Individual variation and intraclass correlation in arachidonic acid and eicosapentaenoic acid in chicken muscle

Chicken meat with reduced concentration of arachidonic acid (AA) and reduced ratio between omega-6 and omega-3 fatty acids has potential health benefits because a reduction in AA intake dampens prostanoid signaling, and the proportion between omega-6 and omega-3 fatty acids is too high in our diet. Analyses for fatty acid determination are expensive, and finding the optimal number of analyses to give reliable results is a challenge. The objective of the present study was i) to analyse the intraclass correlation of different fatty acids in five meat samples, of one gram each, within the same chicken thigh, and ii) to study individual variations in the concentrations of a range of fatty acids and the ratio between omega-6 and omega-3 fatty acid concentrations among fifteen chickens. Fifteen newly hatched broilers were fed a wheat-based diet containing 4% rapeseed oil and 1% linseed oil for three weeks. Five muscle samples from the mid location of the thigh of each chicken were analysed for fatty acid composition. The intraclass correlation (sample correlation within the same animal) was 0.85-0.98 for the ratios of total omega-6 to total omega-3 fatty acids and of AA to eicosapentaenoic acid (EPA). This indicates that when studying these fatty acid ratios, one sample of one gram per animal is sufficient. However, due to the high individual variation between chicken for these ratios, a relatively high number of animals (minimum 15) are required to obtain a sufficiently high power to reveal significant effects of experimental factors (e.g. feeding regimes). The present experiment resulted in meat with a favorable concentration ratio between omega-6 and omega-3 fatty acids. The AA concentration varied from 1.5 to 2.8 g/100 g total fatty acids in thigh muscle in the fifteen broilers, and the ratio between AA and EPA concentrations ranged from 2.3 to 3.9. These differences among the birds may be due to genetic variance that can be exploited by breeding for lower AA concentration and/or a more favorable AA/EPA ratio to produce meat with health benefits.

Characterization of scavengers of gamma-ketoaldehydes that do not inhibit prostaglandin biosynthesis

Expression of cyclooxygenase-2 (COX-2) is associated with the development of many pathologic conditions. The product of COX-2, prostaglandin H(2) (PGH(2)), can spontaneously rearrange to form reactive gamma-ketoaldehydes called levuglandins (LGs). This gamma-ketoaldehyde structure confers a high degree of reactivity on the LGs, which rapidly form covalent adducts with primary amines of protein residues. Formation of LG adducts of proteins has been demonstrated in pathologic conditions (e.g., increased levels in the hippocampus in Alzheimer's disease) and during physiologic function (platelet activation). On the basis of knowledge that lipid modification of proteins is known to cause their translocation and to alter their function, we hypothesize that modification of proteins by LG could have functional consequences. Testing this hypothesis requires an experimental approach that discriminates between the effects of protein modification by LG and the effects of cyclooxygenase-derived prostanoids acting through their G-protein coupled receptors. To achieve this goal, we have synthesized and evaluated a series of scavengers that react with LG with a potency more than 2 orders of magnitude greater than that with the epsilon-amine of lysine. A subset of these scavengers are shown to block the formation of LG adducts of proteins in cells without inhibiting the catalytic activity of the cyclooxygenases. Ten of these selective scavengers did not produce cytotoxicity. These results demonstrate that small molecules can scavenge LGs in cells without interfering with the formation of prostaglandins. They also provide a working hypothesis for the development of pharmacologic agents that could be used in experimental animals in vivo to assess the pathophysiological contribution of levuglandins in diseases associated with cyclooxygenase up-regulation.

Eicosanoids and cancer

Eicosanoids, including prostaglandins and leukotrienes, are biologically active lipids that have been implicated in various pathological processes, such as inflammation and cancer. This Review highlights our understanding of the intricate roles of eicosanoids in epithelial-derived tumours and their microenvironment. The knowledge of how these lipids orchestrate the complex interactions between transformed epithelial cells and the surrounding stromal cells is crucial for understanding tumour evolution, progression and metastasis. Understanding the molecular mechanisms underlying the role of prostaglandins and other eicosanoids in cancer progression will help to develop more effective cancer chemopreventive and/or therapeutic agents.

Cyclooxygenase-2 and cancer treatment: understanding the risk should be worth the reward

Targeting the prostaglandin (PG) pathway is potentially a critical intervention for the prevention and treatment of cancer. Central to PG biosynthesis are two isoforms of cyclooxygenase (COX 1 and 2), which produce prostaglandin H(2) (PGH(2)) from plasma membrane stores of fatty acids. COX-1 is constitutively expressed, whereas COX-2 is an inducible isoform upregulated in many cancers. Differences between COX-1 and COX-2 catalytic sites enabled development of selective inhibitors. Downstream of the COX enzymes, prostaglandin E(2) synthase converts available PGH(2) to prostaglandin E(2) (PGE(2)), which can stimulate cancer progression. Significant research efforts are helping identify more selective targets and fully elucidate the downstream targets of prostaglandin E(2)-mediated oncogenesis. Nonetheless, as a key rate-limiting control point of PG biosynthesis, COX-2 continues to be an important anticancer target. As we embark upon a new era of individualized medicine, a better understanding of the individual risk and/or benefit involved in COX-2 selective targeting is rapidly evolving. This review endeavors to summarize developments in our understanding of COX-2 and its downstream targets as vital areas of anticancer research and to provide the current status of an exciting aspect of molecular medicine.

Cancer-Associated Fibroblasts Are Activated in Incipient Neoplasia to Orchestrate Tumor-Promoting Inflammation in an NF-kappaB-Dependent Manner

Cancer-associated fibroblasts (CAFs) support tumorigenesis by stimulating angiogenesis, cancer cell proliferation, and invasion. We demonstrate that CAFs also mediate tumor-enhancing inflammation. Using a mouse model of squamous skin carcinogenesis, we found a proinflammatory gene signature in CAFs isolated from dysplastic skin. This signature was maintained in CAFs from subsequent skin carcinomas and was evident in mammary and pancreatic tumors in mice and in cognate human cancers. The inflammatory signature was already activated in CAFs isolated from the initial hyperplastic stage in multistep skin tumorigenesis. CAFs from this pathway promoted macrophage recruitment, neovascularization, and tumor growth, activities that are abolished when NF-kappaB signaling was inhibited. Additionally, we show that normal dermal fibroblasts can be "educated" by carcinoma cells to express proinflammatory genes.

Inflammation and cancer: interweaving microRNA, free radical, cytokine and p53 pathways

Chronic inflammation and infection are major causes of cancer. There are continued improvements to our understanding of the molecular connections between inflammation and cancer. Key mediators of inflammation-induced cancer include nuclear factor kappa B, reactive oxygen and nitrogen species, inflammatory cytokines, prostaglandins and specific microRNAs. The collective activity of these mediators is largely responsible for either a pro-tumorigenic or anti-tumorigenic inflammatory response through changes in cell proliferation, cell death, cellular senescence, DNA mutation rates, DNA methylation and angiogenesis. As our understanding grows, inflammatory mediators will provide opportunities to develop novel diagnostic and therapeutic strategies. In this review, we provide a general overview of the connection between inflammation, microRNAs and cancer and highlight how our improved understanding of these connections may provide novel preventive, diagnostic and therapeutic strategies to reduce the health burden of cancer.

The role of COX-2 in intestinal inflammation and colorectal cancer

Colorectal cancer (CRC) is a heterogeneous disease, including at least three major forms: hereditary, sporadic and colitis-associated CRC. A large body of evidence indicates that genetic mutations, epigenetic changes, chronic inflammation, diet and lifestyle are the risk factors for CRC. As elevated cyclooxygenase-2 (COX-2) expression was found in most CRC tissue and is associated with worse survival among CRC patients, investigators have sought to evaluate the effects of nonsteroidal anti-inflammatory drugs (NSAIDs) and selective COX-2 inhibitors (COXIBs) on CRC. The epidemiological studies, clinical trials and animal experiments indicate that NSAIDs are among the most promising chemopreventive agents for this disease. NSAIDs exert their anti-inflammatory and antitumor effects primarily by reducing prostaglandin production by inhibition of COX-2 activity. In this review, we highlight breakthroughs in our understanding of the roles of COX-2 in CRC and inflammatory bowel disease. These recent data provide a rationale for re-evaluating COX-2 as both the prognostic and the predictive marker in a wide variety of malignancies and for renewing the interest in evaluating relative benefits and risk of COXIBs in appropriately selected patients for cancer prevention and treatment.