Non-steroidal anti-inflammatory drugs for cancer prevention: promise, perils and pharmacogenetics

Novel lipid mediators and resolution mechanisms in acute inflammation: to resolve or not?

Because inflammation is appreciated as a unifying basis of many widely occurring diseases, the mechanisms involved in its natural resolution are of considerable interest. Using contained, self-limited inflammatory exudates and a systems approach, novel lipid-derived mediators and pathways were uncovered in the resolution of inflammatory exudates. These new families of local mediators control both the duration and magnitude of acute inflammation as well as the return of the site to homeostasis in the process of catabasis. This new genus of specialized proresolving mediators (SPM) includes essential fatty acid-derived lipoxins, resolvins, protectins, and, most recently, maresins. These families were named based on their unique structures and potent stereoselective actions. The temporally initiated biosynthesis of SPM and their direct impact on leukocyte trafficking and macrophage-directed clearance mechanisms provide clear evidence that resolution is an active, programmed response at the tissue level. Moreover, SPM that possess anti-inflammatory (ie, limiting PMN infiltration) and proresolving (enhance macrophage uptake and clearance of apoptotic PMN and microbial particles) actions as well as stimulating mucosal antimicrobial responses demonstrate that anti-inflammation and proresolution are different responses of the host and novel defining properties of these molecules. The mapping of new resolution circuits has opened the possibility for understanding mechanisms that lead from acute to chronic inflammation, or to the resolution thereof, as well as to potential, resolution-based immunopharmacological therapies.

Antidepressant use and colorectal cancer risk: a Danish population-based case-control study

Background:

Earlier research suggests that use of selective serotonin reuptake inhibitors (SSRIs), but not tricyclic antidepressants (TCAs), reduces the risk of colorectal cancer (CRC).

Methods:

We conducted a population-based case–control study to investigate the association between antidepressant use and CRC risk. Cases were diagnosed with a first primary CRC from 1991 through 2008. We selected 10 population controls matched to cases on sex, birth year, and residence from the Danish Civil Registration System using risk-set sampling. We estimated the odds ratios (ORs) and 95% confidence intervals (CIs) associating antidepressant use with colorectal cancer occurrence, controlling for potential confounders.

Results:

The study included 9979 cases and 99 790 controls. We found no notable reduction in CRC risk in ever users (⩾2 prescriptions) of TCAs (OR=0.94; 95% CI: 0.84, 1.05), SSRIs (OR=0.97; 95% CI: 0.90, 1.05), or other antidepressants (OR=0.95; 95% CI: 0.83, 1.07). Associations for recent and former use of antidepressants were also near null. Intensity of antidepressant use (number of pills divided by total duration of use), regardless of duration, was not associated with CRC risk.

Conclusions:

We found no evidence that antidepressant use substantially reduces the risk of colorectal cancer.

Memory B cells from older people express normal levels of cyclooxygenase-2 and produce higher levels of IL-6 and IL-10 upon in vitro activation

Worldwide the elderly population is increasing. The elderly show deficiencies in immune function. B lymphocytes are essential elements of the immune system responsible for antibody production. This laboratory previously showed that activated human B cells isolated from young adults express cyclooxygenase-2 (Cox-2) and that Cox-2 is essential for optimal antibody responses. Recent data suggests that Cox-2 expression decreases with age in mouse bone tissue. There is no information regarding Cox-2 expression in B cells from older human subjects. We investigated the expression and activity of Cox-2 in naïve and memory B cells from older people. We show that B cells from older subjects show similar Cox-2 protein expression and activity, antibody production and proliferation compared to younger people. However, we found that activated memory B cells from older people produce higher levels of IL-6 and IL-10 compared to young adults. Therefore, the dysregulated cytokine production could contribute to immune senescence in the elderly.

Combinatorial chemoprevention reveals a novel smoothened-independent role of GLI1 in esophageal carcinogenesis

Reflux-induced injury promotes esophageal adenocarcinoma, one of the most rapidly increasing, highly lethal cancers in Western countries. Here, we investigate the efficacy of a combinatorial chemoprevention strategy for esophageal adenocarcinoma and characterize the underlying molecular mechanisms. Specifically, our approach involves the use of ursodeoxycholic acid (Urso) due to its ability to decrease injury-inducing bile salts in combination with Aspirin to mitigate the consequences of injury. We find that Urso-Aspirin combination reduces the risk of adenocarcinoma in vivo in animals with reflux, decreases the proliferation of esophageal adenocarcinoma cells, and downregulates a key cell cycle regulator, CDK2. Mechanistically, using cell growth, luciferase reporter, expression, and chromatin immunoprecipitation assays, we identify GLI1, a Hedgehog-regulated transcription factor, as a novel target of Urso-Aspirin combination. We show that GLI1 is upregulated during esophageal carcinogenesis, and GLI1 can bind to the CDK2 promoter and activate its expression. Although the Urso-Aspirin combination downregulates GLI1, the GLI1 overexpression not only abrogates the effect of this combination on proliferation but it also restores CDK-2 expression. These findings support that the chemopreventive effect of the Urso-Aspirin combination occurs, at least in part, through a novel GLI1-CDK2-dependent mechanism. To further understand the regulation of CDK2 by GLI1, both pharmacologic and RNAi-mediated approaches show that GLI1 is a transcriptional activator of CDK2, and this regulation occurs independent of Smoothened, the central transducer of the Hedgehog canonical pathway. Collectively, these results identify a novel GLI1-to-CDK2 pathway in esophageal carcinogenesis, which is a bona fide target for effective combinatorial chemoprevention with Urso and Aspirin.

Sperm and oocyte communication mechanisms controlling C. elegans fertility

During sexual reproduction in many species, sperm and oocyte secrete diffusible signaling molecules to help orchestrate the biological symphony of fertilization. In the Caenorhabditis elegans gonad, bidirectional signaling between sperm and oocyte is important for guiding sperm to the fertilization site and inducing oocyte maturation. The molecular mechanisms that regulate sperm guidance and oocyte maturation are being delineated. Unexpectedly, these mechanisms are providing insight into human diseases, such as amyotrophic lateral sclerosis, spinal muscular atrophy, and cancer. Here we review sperm and oocyte communication in C. elegans and discuss relationships to human disorders.

Cancer inflammation and regulatory T cells

Chronic inflammation is essential for cancer growth and metastasis. It follows that factors reducing inflammation would abrogate cancer and restore tissue health. However, roles for anti-inflammatory CD4+ regulatory cells (T(REG)) in cancer are enigmatic and controversial. Our recent data reveal that T(REG) may function in cancer similarly to inflammatory bowel disease or multiple sclerosis, whereby T(REG) accumulate but lack potency to restore tissue homeostasis under inflammatory conditions. Interestingly, early life exposures to diverse environmental organisms reinforce a protective T(REG) phenotype that inhibits cancer. In contrast, hygienic individuals with few exposures earlier in life suffer from a dysregulated T(REG) feedback loop. Consequently, hygienic subjects have increased risk of malignancy later in life. This cancer condition is reversible by blocking underlying inflammation. Taken together, these data help explain increased inflammation-associated cancer rates in hygienic societies and identify targets to abrogate cancer and restore overall health.

Polymorphic human prostaglandin H synthase-2 proteins and their interactions with cyclooxygenase substrates and inhibitors

The cyclooxygenase (COX) activity of prostaglandin H synthase-2 (PGHS-2) is implicated in colorectal cancer and is targeted by nonsteroidal anti-inflammatory drugs (NSAIDs) and dietary n-3 fatty acids. We used purified, recombinant proteins to evaluate the functional impacts of the R228H, E488G, V511A and G587R PGHS-2 polymorphisms on COX activity, fatty acid selectivity and NSAID actions. Compared to wild-type PGHS-2, COX activity with arachidonate was ∼20% lower in 488G and ∼20% higher in 511A. All variants showed time-dependent inhibition by the COX-2-specific inhibitor (coxib) nimesulide, but 488G and 511A had 30-60% higher residual COX activity; 511A also showed up to 70% higher residual activity with other time-dependent inhibitors. In addition, 488G and 511A differed significantly from wild type in Vmax values with the two fatty acids: 488G showed ∼20% less and 511A showed ∼20% more discrimination against eicosapentaenoic acid. The Vmax value for eicosapentaenoate was not affected in 228H or 587R, nor were the Km values or the COX activation efficiency (with arachidonate) significantly altered in any variant. Thus, the E488G and V511A PGHS-2 polymorphisms may predict who will most likely benefit from interventions with some NSAIDs or n-3 fatty acids.

Celecoxib-loaded liposomes: effect of cholesterol on encapsulation and in vitro release characteristics

CLX (celecoxib) is a highly hydrophobic non-steroidal anti-inflammatory drug with high plasma protein binding. We describe here the encapsulation of CLX in MLVs (multilamellar vesicles) composed of DSPC (1,2-distearoyl-sn-glycero-3-phosphocholine) and variable amounts of cholesterol. The effects of cholesterol content on liposome size, percentage drug loading and in vitro drug release profiles were investigated. Differential scanning calorimetry and FTIR (Fourier-transform infrared) spectroscopy were used to determine molecular interactions between CLX, cholesterol and DSPC. The phase transition temperature (Tm) of vesicles was reduced in a synergistic manner in the presence of both CLX and cholesterol. Encapsulation efficiency, loading and release of CLX decreased with increasing cholesterol content. FTIR results indicated that this decrease was due to a competition between CLX and cholesterol for the co-operativity region of the phospholipids. In the presence of cholesterol, CLX was pushed further into the hydrophobic core of the bilayer. However, MLVs prepared with DSPC only (without cholesterol) exhibited the lowest ability for drug retention after 72 h. Our results indicated that CLX, without the requirement of modifications to enhance solubilization, can be encapsulated and released from liposomal formulations. This method of drug delivery may be used to circumvent the low bioavailability and systemic side effects of oral CLX formulations.

NSAIDs, Mitochondria and Calcium Signaling: Special Focus on Aspirin/Salicylates

Aspirin (acetylsalicylic acid) is a well-known nonsteroidal anti-inflammatory drug (NSAID) that has long been used as an anti-pyretic and analgesic drug. Recently, much attention has been paid to the chemopreventive and apoptosis-inducing effects of NSAIDs in cancer cells. These effects have been thought to be primarily attributed to the inhibition of cyclooxygenase activity and prostaglandin synthesis. However, recent studies have demonstrated unequivocally that certain NSAIDs, including aspirin and its metabolite salicylic acid, exert their anti-inflammatory and chemopreventive effects independently of cyclooxygenase activity and prostaglandin synthesis inhibition. It is becoming increasingly evident that two potential common targets of NSAIDs are mitochondria and the Ca²⁺ signaling pathway. In this review, we provide an overview of the current knowledge regarding the roles of mitochondria and Ca²⁺ in the apoptosis-inducing effects as well as some side effects of aspirin, salicylates and other NSAIDs, and introducing the emerging role of L-type Ca²⁺ channels, a new Ca²⁺ entry pathway in non-excitable cells that is up-regulated in human cancer cells.

Prostaglandin E2 prevents Helicobacter-induced gastric preneoplasia and facilitates persistent infection in a mouse model

BACKGROUND & AIMS

Persistent infection with the human pathogen Helicobacter pylori increases the risk of gastric cancer. In this study, we investigated the role of cyclooxygenase-2 (COX-2) and its main product, prostaglandin E(2) (PGE(2)), in the development of Helicobacter-induced gastritis and gastric cancer precursor lesions.

METHODS

We utilized mouse models of Helicobacter-induced gastric preneoplasia and vaccine-induced protection to study the effects of COX-2 inhibition and PGE(2) treatment on the induction of Helicobacter-specific immune responses and gastric premalignant immunopathology.

RESULTS

COX-2 and PGE(2) are up-regulated upon Helicobacter infection in cultured epithelial cells and in the gastric mucosa of infected mice. Inhibition of COX-2 activity with celecoxib significantly accelerated early preneoplasia; conversely, systemic administration of synthetic PGE(2) prevented development of premalignant pathology and completely reversed preexisting lesions by suppressing interferon-gamma production in the infected stomachs. The protective effect of PGE(2) was accompanied by increased Helicobacter colonization in all models. All in vivo effects were attributed to immunosuppressive effects of PGE(2) on CD4(+) T-helper 1 cells, which fail to migrate, proliferate, and secrete cytokines when exposed to PGE(2) in vitro and in vivo. T-cell inhibition was found to be due to silencing of interleukin-2 gene transcription, and could be overcome by supplementation with recombinant interleukin-2 in vitro and in vivo.

CONCLUSIONS

COX-2-dependent production of PGE(2) has an important immunomodulatory role during Helicobacter infection, preventing excessive local immune responses and the associated immunopathology by inhibiting the effector functions of pathogenic T-helper 1 cells.

Prescriptions for selective cyclooxygenase-2 inhibitors, non-selective non-steroidal anti-inflammatory drugs, and risk of breast cancer in a population-based case-control study

INTRODUCTION

Non-steroidal anti-inflammatory drugs (NSAIDs) prevent the growth of mammary tumours in animal models. Two population-based case-control studies suggest a reduced risk of breast cancer associated with selective cyclooxygenase-2 (sCox-2) inhibitor use, but data regarding the association between breast cancer occurrence and use of non-selective NSAIDs are conflicting.

METHODS

We conducted a population-based case-control study using Danish healthcare databases to examine if use of NSAIDs, including sCox-2 inhibitors, was associated with a reduced risk of breast cancer. We included 8,195 incident breast cancer cases diagnosed in 1991 through 2006 and 81,950 population controls.

RESULTS

Overall, we found no reduced breast cancer risk in ever users (>2 prescriptions) of sCox-2 inhibitors (odds ratio (OR) = 1.08, 95% confidence interval (95% CI) = 0.99, 1.18), aspirin (OR = 0.98, 95% CI = 0.90-1.07), or non-selective NSAIDs OR = 1.04, (95% CI = 0.98, 1.10)). Recent use (>2 prescriptions within two years of index date) of sCox-2 inhibitors, aspirin, or non-selective NSAIDs was likewise not associated with breast cancer risk (Ors = 1.06 (95% CI = 0.96, 1.18), 0.96 (95% CI = 0.87, 1.06) and 0.99 (95% CI = 0.85, 1.16), respectively). Risk estimates by duration (<10, 10 to 15, 15+ years) or intensity (low/medium/high) of NSAID use were also close to unity. Regardless of intensity, shorter or long-term NSAID use was not significantly associated with breast cancer risk.

CONCLUSIONS

Overall, we found no compelling evidence of a reduced risk of breast cancer associated with use of sCox-2 inhibitors, aspirin, or non-selective NSAIDs.

Anti-cancer effects of celecoxib in head and neck carcinoma

Although many studies highlighted cyclooxygenase2 (COX2) inhibition as a promising therapeutic strategy for cancer, more evidence is needed for clinical application. The purpose of this study was to investigate the feasibility of COX2 inhibition as a strategic treatment modality for head and neck carcinoma (HNC). We tested COX2 inhibitor, celecoxib in six types of HNC cells and analyzed the expression changes in proteins related to angiogenesis and apoptosis in vitro. We also evaluated proliferation, gelatinolysis and in vitro invasion. We used a hamster carcinogenesis model and a mouse tumorigenesis model for the in vivo evaluation of COX2 inhibition. We performed immunohistochemistry to assess changes in the expression of COX2, survivin and angiogenesis. Celecoxib administration caused decreases in the expressions of COX2, VEGF and survivin in vitro. Proliferation, in vitro invasion and gelatinolytic activity were reduced in HNC cell lines, but the effect was inconsistent across lines. COX2 inhibition retarded oral carcinogenesis from an early carcinogenic stage with increased apoptosis and decreased survivin expression. COX2 inhibition did not inhibit tumor growth, even with the COX2 downregulation and decrease in neovascularization. We conclude that COX2 inhibition has a chemopreventive effect, but its application as a treatment of HNC in a clinical setting still requires further research to overcome its limited anti-cancer effects.

Celecoxib enhanced the sensitivity of cancer cells to anticancer drugs by inhibition of the expression of P-glycoprotein through a COX-2-independent manner

The P-glycoprotein (p170, P-gp) encoded by human MDR1 gene functions as a pump to extrude anticancer drugs from cancer cells. Over-expression of p170 is closely related to primary and induced drug resistance phenotype of tumor cells. Recent studies have demonstrated that expression of cyclooxygenase-2 (COX-2) is positively correlated with the p170 level, suggesting a potential of COX-2 specific inhibitors in regulation of cytotoxicity of anticancer agents. Celecoxib is one of the specific inhibitors of COX-2 and has been widely used in clinic. However, its function in the response of cancer cells to anticancer drugs and the related mechanism are still waiting to be investigated. To explore the correlation of celecoxib and the p170-mediated drug resistance, the role of celecoxib in drug response of cancer cells was analyzed with flow cytometry, high performance liquid chromatography (HPLC), and colony formation experiments. Celecoxib (50 microM) was found to significantly enhance the sensitivity of MCF-7 and JAR/VP16 cells to tamoxifen and etoposide, respectively, by inhibition of p170 expression and increase in intracellular accumulation of the drugs. However, celecoxib did not affect pump function of p170. Enzyme activity and methylation analyses demonstrated that the inhibitory effect of celecoxib on p170 was independent on COX-2 but closely related to hypermethylation of MDR1 gene promoter. Our study suggested that celecoxib was a potential agent for enhancement of the sensitivity of cancer cells to anticancer drugs. It also provided a links between epigenetic change of MDR1 and drug response of cancer cells.

Cyclooxygenase-2 inhibition inhibits PI3K/AKT kinase activity in epithelial ovarian cancer

Cyclooxygenase-2 (COX-2) expression contributes to tumor growth and invasion in epithelial ovarian cancer (EOC). COX-2 inhibitors exhibit important anticarcinogenic potential against EOC, but the molecular mechanisms underlying this effect and relation with PI3-kinase/AKT signaling remain the subject of intense investigations. Therefore, the role of COX-2 in EOC and its cross talk with PI3-kinase/AKT pathway were investigated using a large series of EOC tissues in a tissue micro array (TMA) format followed by in vitro and in vivo studies using EOC cell lines and NUDE mice. Clinically, COX-2 was overexpressed in 60.3% of EOC and was significantly associated with activated AKT (p < 0.0001). Cox-1 expression was seen in 59.9% but did not associate with AKT. Our in vitro data using EOC cell line showed that inhibition of COX-2 by aspirin, selective inhibitor NS398 and gene silencing by COX-2 specific siRNA impaired phosphorylation of AKT resulting decreased downstream signaling leading to cell growth inhibition and induction of apoptosis. Finally, treatment of MDAH2774 cell line xenografts with aspirin resulted in growth inhibition of tumors in NUDE mice via down-regulation of COX-2 and AKT activity. These data identify COX-2 as a potential biomarker and therapeutic target in distinct molecular subtypes of ovarian cancer.

Cyclooxygenase-2 Gly587Arg variant is associated with differential enzymatic activity and risk of esophageal squamous-cell carcinoma

Functional SNPs in the COX-2 promoter region have been associated with susceptibility to esophageal squamous-cell carcinoma (ESCC). In this study, we investigated SNPs in the COX-2 coding region and their impact on risk of ESCC. The coding region of COX-2 in DNAs from 30 Han Chinese individuals was sequenced to identify SNPs. Different coding region variants identified were cloned and expressed in MCE-7 cells for the measurement of COX-2 enzymatic activity. Genotypes were determined by PCR-RFLP in 1026 patients with ESCC and 1270 controls and odds ratios (ORs) and 95% confidence intervals (CI) were computed by logistic regression model. A SNP at exon 10 (1759G>A, rs3218625) was identified, which causes (587)Gly to (587)Arg amino acid substitution. Enzymatic assays using different recombinant COX-2 variants showed that COX-2-(587)Arg had significantly higher activity towards arachidonic acid than COX-2-(587)Gly (13.8 +/- 3.2 U/mg vs. 11.2 +/- 2.4 U/mg; P = 0.012). Case-control analysis showed that 10.2% of ESCC patients carried the 1759A allele whereas only 5.4% of controls had this allele (P < 0.0001). No homozygous 1759AA genotype was presented in controls albeit two patients carrying this genotype. Multivariate logistic regression analysis revealed that subjects with at least one 1759A allele had increased risk for the development of ESCC (OR, 1.91; 95% CI, 1.39-2.62) compared with those with the 1759GG genotype. These results extend our previous findings and indicate that inherited variant in arachidonic acid-metabolizing enzyme, which results in heightened enzymatic activity, may confer susceptibility to ESCC.

Inflammation: a driving force speeds cancer metastasis

It has been increasingly recognized that tumor microenvironment plays an important role in carcinogenesis. Inflammatory component is present and contributes to tumor proliferation, angiogenesis, metastasis and resistance to hormonal and chemotherapy. This review highlights the role of inflammation in the tumor metastasis. We focus on the function of proinflammatory factors, particularly cytokines during tumor metastasis. Understanding of the mechanisms by which inflammation contributes to metastasis will lead to innovative approach for treating cancer. How tumor spread remains an enigma and has received great attention in recent years, as metastasis is the major cause of cancer mortality. The complex and highly selective metastatic cascade not only depends on the intrinsic properties of tumor cells but also the microenvironment that they derive from. An inflammatory milieu consisting of infiltrated immune cells and their secretory cytokines, chemokines and growth factors contribute significantly to the invasive and metastatic traits of cancer cells. Here, we review new insights into the molecular pathways that link inflammation in the tumor microenvironment to metastasis.

Cyclooxygenase-2 polymorphisms, aspirin treatment, and risk for colorectal adenoma recurrence--data from a randomized clinical trial

Cyclooxygenase-2 (COX-2) catalyzes the rate-limiting step in the production of prostaglandins, potent mediators of inflammation. Chronic inflammation plays an important role in the development and progression of colorectal cancer. Aspirin inhibits COX-2 activity and lowers the risk for colorectal adenomas and cancer. We investigated whether common genetic variation in COX-2 influenced risk for colorectal adenoma recurrence among 979 participants in the Aspirin/Folate Polyp Prevention Study who were randomly assigned to placebo or aspirin and followed for 3 years for the occurrence of new adenomas. Of these participants, 44.2% developed at least one new adenoma during follow-up. Adjusted relative risks and 95% confidence intervals (95% CI) were calculated to test the association between genetic variation at six COX-2 single-nucleotide polymorphisms and adenoma occurrence and interaction with aspirin treatment. Two single-nucleotide polymorphisms were significantly associated with increased adenoma recurrence: for rs5277, homozygous carriers of the minor C allele had a 51% increased risk compared with GG homozygotes (relative risk, 1.51; 95% CI, 1.01-2.25), and for rs4648310, heterozygous carriers of the minor G allele had a 37% increased risk compared with AA homozygotes (relative risk, 1.37; 95% CI, 1.05-1.79). (There were no minor allele homozygotes.) In stratified analyses, there was suggestive evidence that rs4648319 modified the effect of aspirin. These results support the hypothesis that COX-2 plays a role in the etiology of colon cancer and may be a target for aspirin chemoprevention and warrant further investigation in other colorectal adenoma and cancer populations.

Targeting NRF2 signaling for cancer chemoprevention

Modulation of the metabolism and disposition of carcinogens through induction of cytoprotective enzymes is one of several promising strategies to prevent cancer. Chemopreventive efficacies of inducers such as dithiolethiones and sulforaphane have been extensively studied in animals as well as in humans. The KEAP1-NRF2 system is a key, but not unilateral, molecular target for these chemopreventive agents. The transcription factor NRF2 (NF-E2-related factor 2) is a master regulator of the expression of a subset of genes, which produce proteins responsible for the detoxication of electrophiles and reactive oxygen species as well as the removal or repair of some of their damage products. It is believed that chemopreventive enzyme inducers affect the interaction between KEAP1 and NRF2 through either mediating conformational changes of the KEAP1 protein or activating phosphorylation cascades targeting the KEAP1-NRF2 complex. These events in turn affect NRF2 stability and trafficking. Recent advances elucidating the underlying structural biology of KEAP1-NRF2 signaling and identification of the gene clusters under the transcriptional control of NRF2 are facilitating understanding of the potential pleiotropic effects of NRF2 activators and discovery of novel classes of potent chemopreventive agents such as the triterpenoids. Although there is appropriately a concern regarding a deleterious role of the KEAP1-NRF2 system in cancer cell biology, especially as the pathway affects cell survival and drug resistance, the development and the use of NRF2 activators as chemopreventive agents still holds a great promise for protection of normal cells from a diversity of environmental stresses that contribute to the burden of cancer and other chronic, degenerative diseases.

Dissection of the transformation of primary human hematopoietic cells by the oncogene NUP98-HOXA9

NUP98-HOXA9 is the prototype of a group of oncoproteins associated with acute myeloid leukemia. It consists of an N-terminal portion of NUP98 fused to the homeodomain of HOXA9 and is believed to act as an aberrant transcription factor that binds DNA through the homeodomain. Here we show that NUP98-HOXA9 can regulate transcription without binding to DNA. In order to determine the relative contributions of the NUP98 and HOXA9 portions to the transforming ability of NUP98-HOXA9, the effects of NUP98-HOXA9 on primary human CD34+ cells were dissected and compared to those of wild-type HOXA9. In contrast to previous findings in mouse cells, HOXA9 had only mild effects on the differentiation and proliferation of primary human hematopoietic cells. The ability of NUP98-HOXA9 to disrupt the differentiation of primary human CD34+ cells was found to depend primarily on the NUP98 portion, whereas induction of long-term proliferation required both the NUP98 moiety and an intact homeodomain. Using oligonucleotide microarrays in primary human CD34+ cells, a group of genes was identified whose dysregulation by NUP98-HOXA9 is attributable primarily to the NUP98 portion. These include RAP1A, HEY1, and PTGS2 (COX-2). Their functions may reflect the contribution of the NUP98 moiety of NUP98-HOXA9 to leukemic transformation. Taken together, these results suggest that the effects of NUP98-HOXA9 on gene transcription and cell transformation are mediated by at least two distinct mechanisms: one that involves promoter binding through the homeodomain with direct transcriptional activation, and another that depends predominantly on the NUP98 moiety and does not involve direct DNA binding.

Current concepts in colorectal cancer prevention

Colorectal cancer chemoprevention, or chemoprophylaxis, is a drug-based approach to prevent colorectal cancer. Preventing colorectal adenomas with currently available agents demonstrates the promise of pharmacologic strategies directed at critical regulatory pathways. However, agent toxicity, lesion breakthrough and competing efficacy from endoscopy procedures challenge population-based implementation. This article reviews the role of colorectal cancer chemoprevention in the context of existing screening and surveillance guidelines and practice. Emphasis is placed on the role of the colorectal adenoma as a cancer precursor and its surrogacy in assessing individual risk and for evaluating chemoprevention efficacy. We discuss the importance of risk stratification for identifying subjects at moderate-to-high risk for colorectal cancer who are most likely to benefit from chemoprevention at an acceptable level of risk.

American Ginseng inhibits induced COX-2 and NFKB activation in breast cancer cells

BACKGROUND

Epidemiologic evidence suggests reduced breast cancer mortality in users of American Ginseng (AG) (Panax quinquefolium). We hypothesized that AG extract decreases proliferation of human breast cancer cells via an anti-inflammatory effect applicable to the prevention of breast and other cancers.

MATERIAL AND METHODS

A defined lyophilized aqueous extract of AG (LEAG) was dissolved in DMSO 1mg/mL, and serially diluted in saline. The cell lines MDA MB 231 and MCF7 were stimulated with the phorbol ester PDBu and treated with 100-500 mcg/mL LEAG. Proliferation was measured by MDA assay. Induced COX-2 expression was assayed by ELISA. Activation of NFkappaB by phosphorylation of the p65 subunit was quantified by CASE (cellular activation of signaling ELISA).

RESULTS

Both cell lines had reduced proliferation when treated with LEAG. PDBu stimulation of MDA MB 231 increased expression of the COX-2 protein 20-fold at 48 hours (P<0.005). COX-2 protein expression remained at baseline concentrations in PDBu- treated MDA MB 231 cells exposed to 100 mcg/mL LEAG. The CASE assay showed a 4-fold increase in p65 activation 24 hours after PDBu treatment in normal medium, while phosphorylated p65 dropped below baseline in the cells treated with PDBu plus LEAG.

CONCLUSION

In MDA MB 231, COX-2 was inducible with PDBu. This induced COX-2 expression was blocked by 100 microgram/mL LEAG in a time course consistent with the decline in the activated p65 subunit of NFkappaB. These results provide an anti-inflammatory mechanism for a possible anti-cancer effect of American Ginseng.

Cytochrome P450 2C9 variants influence response to celecoxib for prevention of colorectal adenoma

BACKGROUND & AIMS

Variants in the cytochrome P450 2C9 (CYP2C9) gene are associated with impaired metabolism of celecoxib. We examined the influence of CYP2C9*2 (R144C) and CYP2C9*3 (I359L) variants on dose-related response or toxicity in a randomized trial of celecoxib.

METHODS

We identified individuals with CYP2C9*2 and CYP2C9*3 genotypes (>or=1 variant allele) in the Adenoma Prevention with Celecoxib trial. Following adenoma removal, patients were assigned randomly to groups given placebo or low-dose (200 mg twice daily) or high-dose (400 mg twice daily) celecoxib and underwent follow-up colonoscopies at 1 and/or 3 years.

RESULTS

Among 1660 patients, 21% were CYP2C9*2, and 12% were CYP2C9*3 genotypes. Overall, celecoxib was associated with a dose-dependent reduction in adenoma, compared with placebo, with relative risks (RR) of 0.65 (95% confidence interval [CI]: 0.56-0.76) for the low-dose and 0.54 (95% CI: 0.46-0.63) for the high-dose groups. However, the additional protective effect of the high dose, compared with the low-dose, was observed only in those with CYP2C9*3 genotypes (RR, 0.51; 95% CI: 0.30-0.87). The high dose, compared with low dose, was not associated with significant risk reduction among those with CYP2C9*2 (RR, 0.83; 95% CI: 0.57-1.21) or wild-type (RR, 0.89; 95% CI: 0.72-1.11) genotypes. Compared with placebo, a higher incidence of cardiovascular events was associated with both doses among patients with wild-type genotypes but only with the high dose among patients with variant genotypes.

CONCLUSIONS

The greater efficacy of high-dose celecoxib, compared with the low-dose, in preventing colorectal adenoma appears confined to individuals with slow metabolizer (CYP2C9*3) genotypes. Genetic variability influences susceptibility to the potential benefits and hazards of celecoxib.

Elevated biomarkers of inflammation are associated with reduced survival among breast cancer patients

PURPOSE Chronic inflammation is believed to contribute to the development and progression of breast cancer. Systemic C-reactive protein (CRP) and serum amyloid A (SAA) are measures of low-grade chronic inflammation and potential predictors of cancer survival. PATIENTS AND METHODS We evaluated the relationship between circulating markers of inflammation and breast cancer survival using data from the Health, Eating, Activity, and Lifestyle (HEAL) Study (a multiethnic prospective cohort study of women diagnosed with stage 0 to IIIA breast cancer). Circulating concentrations of CRP and SAA were measured approximately 31 months after diagnosis and tested for associations with disease-free survival (approximately 4.1 years of follow-up) and overall survival (approximately 6.9 years of follow-up) in 734 disease-free breast cancer survivors. Cox proportional hazards models were used with adjustment for potential confounding factors to generate hazard ratios (HRs) and 95% CIs. Results Elevated SAA and CRP were associated with reduced overall survival, regardless of adjustment for age, tumor stage, race, and body mass index (SAA P trend < .0001; CRP P trend = .002). The HRs for SAA and CRP tertiles suggested a threshold effect on survival, rather than a dose-response relationship (highest v lowest tertile: SAA HR = 3.15; 95% CI, 1.73 to 5.65; CRP HR = 2.27; 95% CI, 1.27 to 4.08). Associations were similar and still significant after adjusting for self-reported history of cardiovascular events and censoring cardiovascular disease deaths. Elevated CRP and SAA were also associated with reduced disease-free survival, although these associations were of borderline significance (SAA P trend = .04; CRP P trend = .07). CONCLUSION Circulating SAA and CRP may be important prognostic markers for long-term survival in breast cancer patients, independent of race, tumor stage, and body mass index.

Multiple defects in negative regulation of the PKB/Akt pathway sensitise human cancer cells to the antiproliferative effect of non-steroidal anti-inflammatory drugs

Antitumorigenic effects of non-steroidal anti-inflammatory drugs (NSAIDs) are well established in several types of cancer disease. However, the mechanisms driving these processes are not understood in all details. In our study, we observed significant differences in sensitivity of cancer epithelial cell lines to COX-independent antiproliferative effects of NSAIDs. The prostate cancer cell line LNCaP, lacking both critical enzymes in the negative control of PKB/Akt activation, PTEN and SHIP2, was the most sensitive to these effects, as assessed by analysing the cell cycle profile and expression of cell cycle regulating proteins. We found that p53 protein and its signalling pathway is not involved in early antiproliferative action of the selected NSAID-indomethacin. RNAi provided evidence for the involvement of p21(Cip1/Waf1), but not GDF-15, in antiproliferative effects of indomethacin in LNCaP cells. Interestingly, we also found that indomethacin activated PKB/Akt and induced nuclear localisation of p21(Cip1/Waf1) and Akt2 isoform. Our results are in agreement with other studies and suggest that maintaining of the p21(Cip1/Waf1) level and its intracellular localisation might be influenced by Akt2. Knock-down of SHIP2 by RNAi in PTEN negative prostate and colon cancer cell lines resulted in higher sensitivity to antiproliferative effects of indomethacin. Our data suggest novel mechanisms of NSAIDs antiproliferative action in cancer epithelial cells, which depends on the status of negative regulation of the PKB/Akt pathway and the isoform-specific action of Akt2. Thus, unexpectedly, multiple defects in negative regulation of the PKB/Akt pathway may contribute to increased sensitivity to chemopreventive effects of these widely used drugs.

Microsomal prostaglandin E synthase protein levels correlate with prognosis in colorectal cancer patients

The aim of this study is to investigate the expression of three prostaglandin E synthase (PGES) isomers in colorectal cancer (CRC) tissue and to evaluate their relationship to clinicopathological factors and patient prognosis. Microsomal PGES (mPGES)-1, mPGES-2, cytosolic PGES (cPGES) and cyclooxygenase (COX)-2 protein expression were analyzed by real-time polymerase chain reaction and Western blot. The localization of each PGES and COX-2 protein was examined by immunohistochemistry in 155 surgical resections and correlated to clinicopathological factors and patient prognosis. mPGES-1 mRNA and protein levels were significantly higher in CRC than in paired normal tissues. mPGES-1 immunoreactivity localized in cancer cells in 43% of cases. mPGES-2 immunoreactivity was significantly more pronounced in cancer cells than in adjacent normal epithelium in 36% of cases. cPGES immunoreactivity was homogeneous in cancer cells and thus determined constitutive. mPGES-1 and mPGES-2 correlated with significantly worse prognosis in stage I-III patients. These results indicate that mPGES-1 and mPGES-2 may each play a role in CRC progression.

Interaction of cyclooxygenase-2 variants and smoking in pancreatic cancer: a possible role of nucleophosmin

BACKGROUND & AIMS

Overexpression of cyclooxygenase-2 (COX-2) is implicated in cancer development. This study examined the functional relevance of genetic polymorphisms in the COX-2 promoter and evaluated their associations with susceptibility to pancreatic cancer.

METHODS

Genotypes and haplotypes of COX-2 -765G/C, -1195G/A, and -1290A/G were analyzed in 393 pancreatic cancer patients and 786 controls. Odds ratios (ORs) and 95% confidence intervals (CIs) were computed by logistic regression.The function of the -765G-->C polymorphism was examined by a set of biochemical assays.

RESULTS

The -1195AA or -765GC genotype carriers had a 1.34-fold (95% CI: 1.12-1.60) or 1.63-fold (95% CI: 1.25-2.10) excess risk for developing pancreatic cancer. These 2 variants showed a cooperative effect in context of haplotype, with the ORs for the A(-1195)-C(-765)- containing haplotypes being significantly greater than those for the G(-1195)-G(-765)-containing haplotypes. The -765C allele and smoking displayed a multiplicative joint effect, with an OR of 3.72 (95% CI: 1.70-8.14) for heavy smokers carrying the -765GC genotype. Biochemical assays suggest that the -765G-->C change creates a binding site for nucleophosmin (NPM) and phosphorylated NPM (p-NPM), which acts as a transcriptional inhibitor. Cigarette smoke remarkably increased COX-2 promoter activity, and this effect was more pronounced for the -765C allele compared with the -765G allele. Cigarette smoke reduced nuclear p-NPM levels, which was reversely associated with COX-2 expression.

CONCLUSIONS

Functional COX-2 polymorphisms are associated with susceptibility to pancreatic cancer and tobacco smoke specifically increases -765C promoter activity, which might be mediated by p-NPM.

Role of COX-2 in epithelial-stromal cell interactions and progression of ductal carcinoma in situ of the breast

Epithelial-stromal cell interactions have an important role in breast tumor progression, but the molecular mechanisms underlying these effects are just beginning to be understood. We previously described that fibroblasts promote, whereas normal myoepithelial cells inhibit, the progression of ductal carcinoma in situ (DCIS) to invasive breast carcinomas by using a xenograft model of human DCIS. Here, we report that the tumor growth and progression-promoting effects of fibroblasts are at least in part due to increased COX-2 expression in tumor epithelial cells provoked by their interaction with fibroblasts. Up-regulation of COX-2 in DCIS xenografts resulted in increased VEGF and MMP14 expression, which may contribute to the larger weight and invasive histology of COX-2-expressing tumors. Administration of celecoxib, a selective COX-2 inhibitor, to tumor-bearing mice decreased xenograft tumor weight and inhibited progression to invasion. Coculture of fibroblasts with DCIS epithelial cells enhanced their motility and invasion, and this change was associated with increased MMP14 expression and MMP9 protease activity. We identified the NF-kappaB pathway as one of the mediators of stromal fibroblast-derived signals regulating COX-2 expression in tumor epithelial cells. Inhibition of NF-kappaB and COX-2 activity and down-regulation of MMP9 expression attenuated the invasion-promoting effects of fibroblasts. These findings support a role for COX-2 in promoting the progression of DCIS to invasive breast carcinomas, and suggest that therapeutic targeting of the NF-kappaB and prostaglandin signaling pathways might be used for the treatment and prevention of breast cancer.

Correlates of circulating C-reactive protein and serum amyloid A concentrations in breast cancer survivors

INTRODUCTION

Inflammatory status may be an important prognostic factor for breast cancer. Correlates of markers of inflammation in breast cancer survivors have not been thoroughly evaluated.

METHODS

Using data from, the Health, Eating, Activity, and Lifestyle (HEAL) Study (a population-based, multiethnic prospective cohort study of female breast cancer patients) we evaluated the associations between circulating markers of inflammation (C-reactive protein [CRP] and serum amyloid A [SAA], measured approximately 31 months after diagnosis) and several demographic, lifestyle, and clinical characteristics in 741 disease-free breast cancer survivors. Analysis of variance and regression methods were used for statistical analyses of log-transformed values of CRP and SAA.

RESULTS

After adjusting for age, BMI, ethnicity, and study site, higher concentrations of CRP were associated with increasing concentration of SAA (P-trend < 0.0001), increasing age (P-trend < 0.0001), increasing BMI (P-trend < 0.0001), increasing waist circumference (P-trend < 0.0001), positive history of heart failure (P = 0.0007), decreasing physical activity (P-trend = 0.005), Hispanic ethnicity (P = 0.05 vs. non-Hispanic white), and current smoking (P = 0.03 vs. never smoking). Vitamin E supplementation (P = 0.0005), tamoxifen use (P = 0.008), and radiation treatment (compared to no chemotherapy or radiation; P = 0.04) were associated with reduced CRP. Associations of CRP with clinical characteristics were not significant in the adjusted models. In a multivariate analysis, CRP showed significant associations with waist circumference, BMI, age, history of heart failure, tamoxifen use, and vitamin E supplementation (R (2) = 0.35). Similar, yet fewer, associations were observed for SAA (R (2) = 0.19).

CONCLUSIONS

This study highlights important correlates of inflammatory status in breast cancer patients. Our results are consistent with those from similar studies of healthy women.

Review paper: the role of inflammation in mouse pulmonary neoplasia

Inflammation is a risk factor for the development of many types of neoplasia, including skin, colon, gastric, and mammary cancers, among others. Chronic pulmonary diseases, such as chronic bronchitis and asthma, predispose to lung neoplasia. We will review the mouse literature examining the role of inflammation in lung neoplasia, focusing specifically on genetic susceptibility, pharmacologic modulation of inflammatory pathways, and both transgenic and knockout mouse models used to assess pro- and anti-inflammatory pathways involved in lung neoplasia. Identification of molecular mechanisms that govern the association between inflammation and pulmonary neoplasia could provide novel preventive, diagnostic, and therapeutic strategies for a disease in which few biomarkers currently exist.

Aspirin and other non-steroidal anti-inflammatory drugs and risk of colorectal cancer: a Danish cohort study

OBJECTIVE

The optimal duration and dose of aspirin and non-aspirin non-steroidal anti-inflammatory drugs (NSAIDs) in the potential prevention of colorectal cancer (CRC) have not been established. We examined this issue in the Danish Diet, Cancer, and Health Study.

METHODS

Self-reported NSAID use at entry (January 1995-May 1997) was updated through June 2006, using a nationwide prescription database. CRC incidence was ascertained from nationwide registers. Cox proportional hazards regression was used to compute confounder-adjusted incidence rate ratios (RRs) and 95% confidence intervals (CIs).

RESULTS

From 51,053 cohort subjects, we identified 615 CRC cases during 1995-2006. Daily aspirin use at entry was associated with a decreased risk of CRC (RR, 0.73; 95% CI, 0.49-1.10). A similar risk reduction was seen among subjects with 10 or more prescriptions for aspirin or non-aspirin NSAIDs and five or more years of follow-up. Most aspirin prescriptions were for 75-150 mg aspirin tablets. Among non-aspirin NSAID users, only those with body mass index (BMI) above 25 showed risk reductions [RR, 0.69 (0.47-1.03) for 10 or more prescriptions].

CONCLUSIONS

Long-term consistent use of aspirin or non-aspirin NSAIDs appears necessary to achieve a protective effect against CRC. Further studies of the effective dose of aspirin and the potential interaction between NSAID use and BMI are warranted.

Cyclooxygenase polymorphisms in gastric and colorectal carcinogenesis: are conclusive results available?

OBJECTIVE

Cyclooxygenases (COX) are important enzymes not only in the maintenance of mucosal integrity but also in pathological processes, namely in inflammation and tumor development in the gastrointestinal tract. Our goal was to understand whether there is a clear role for COX polymorphisms in gastric and colorectal carcinogenesis.

METHODS

A systematic review was conducted on observational studies assessing the involvement of COX polymorphisms at the onset of gastric or colorectal lesions, retrieved through a MEDLINE database search by May 2008. The dominant genetic model was assumed for each polymorphism and a random-effect model was used for pooling results.

RESULTS

Twenty-two studies were retrieved reporting a total of 26 COX polymorphisms (nine in COX1 and 17 in COX2 genes). Carriers of -1329A, -899C alleles, and *429TT genotype revealed increased risk for gastric cancer [odds ratio (OR)=1.83; 95% confidence interval (CI): 1.07-3.10, OR=2.02; 95% CI: 1.00-4.10 and OR=1.34; 95% CI: 1.06-1.71, respectively). For colorectal lesions, the -899G>C and -1329G>A polymorphisms also showed an increased risk for cancer (OR=1.35; 95% CI: 1.01-1.81 and OR=1.36; 95% CI: 1.11-1.66, respectively). Furthermore, C allele carriers of V102V single nucleotide polymorphisms presented a decreased risk for colorectal adenoma onset (OR=0.77; 95% CI: 0.58-1.03).

CONCLUSION

Although further studies, namely cohorts and/or adequately matched case-control studies, are required to unravel the impact of most COX polymorphisms, clearly there are evidences that support the involvement of -899G>C and -1329G>A COX2 polymorphisms in either gastric or colorectal carcinogenesis. These markers could be used to optimize management strategies (follow-up and/or chemoprevention).

Long-term use of nonsteroidal anti-inflammatory drugs normalizes the kinetics of gastric epithelial cells in patients with Helicobacter pylori infection via attenuation of gastric mucosal inflammation

BACKGROUND

Helicobacter pylori (H. pylori) is associated with chronic gastritis and gastric carcinogenesis. The effects of nonsteroidal anti-inflammatory drugs (NSAIDs), which exert chemopreventive effects on several cancers, on H. pylori-induced gastritis remain unknown. We investigated the effects of NSAIDs on gastric inflammation and the kinetics of gastric epithelial cells in H. pylori-induced gastritis.

METHODS

Patients with rheumatoid arthritis or osteoarthritis who took NSAIDs for more than 1 month and complained of dyspeptic symptoms were recruited for this study. Patients not on any NSAIDs were included as non-NSAID user controls. All patients underwent diagnostic testing for H. pylori infection, esophagogastroduodenoscopy, and gastric biopsies. Neutrophil infiltration into gastric mucosa, expression of inducible nitric oxide synthase (iNOS), and apoptosis and proliferation of gastric epithelial cells were evaluated by immunohistochemistry. In an in vitro study, the effects of NSAIDs on production of interleukin (IL)-8 induced by H. pylori in a gastric epithelial cell line (AGS) were determined.

RESULTS

Numbers of neutrophils infiltrating the gastric mucosa, iNOS-expressing inflammatory cells and apoptotic cells, and proliferating cells in gastric epithelium were higher in H. pylori-positive groups than H. pylori-negative groups. Among H. pyloripositive groups, these parameters were lower in NSAID users than in non-NSAID users. NSAIDs inhibited the production of IL-8 induced by H. pylori in AGS cells.

CONCLUSIONS

These findings suggest that long-term use of NSAIDs normalizes the kinetics of gastric epithelial cells in patients with H. pylori infection by attenuating gastric mucosal inflammation, which may result in prevention of the gastric carcinogenesis associated with H. pylori infection.

Seed in soil, with an epigenetic view

It is becoming increasingly evident that discrete genetic alterations in neoplastic cells alone cannot explain multistep carcinogenesis whereby tumor cells are able to express diverse phenotypes during the complex phases of tumor development and progression. The epigenetic model posits that the host microenvironment exerts an initial, inhibitory constraint on tumor growth that is followed by acceleration of tumor progression through complex cell-matrix interactions. This review emphasizes the epigenetic aspects of breast cancer development in light of such interactions between epithelial cells ("seed") and the tumor microenvironment ("soil"). Our recent research findings suggest that epigenetic perturbations induced by the tumor microenvironment may play a causal role in promoting breast cancer development. It is believed that abrogation of these initiators could offer a promising therapeutic strategy.

PPARs Mediate Lipid Signaling in Inflammation and Cancer

Lipid mediators can trigger physiological responses by activating nuclear hormone receptors, such as the peroxisome proliferator-activated receptors (PPARs). PPARs, in turn, control the expression of networks of genes encoding proteins involved in all aspects of lipid metabolism. In addition, PPARs are tumor growth modifiers, via the regulation of cancer cell apoptosis, proliferation, and differentiation, and through their action on the tumor cell environment, namely, angiogenesis, inflammation, and immune cell functions. Epidemiological studies have established that tumor progression may be exacerbated by chronic inflammation. Here, we describe the production of the lipids that act as activators of PPARs, and we review the roles of these receptors in inflammation and cancer. Finally, we consider emerging strategies for therapeutic intervention.