Nonsteroidal anti-inflammatory drugs and prevention of colorectal cancer

Mollusc-Derived Brominated Indoles for the Selective Inhibition of Cyclooxygenase: A Computational Expedition

Inflammation plays an important role in different chronic diseases. Brominated indoles derived from the Australian marine mollusk Dicathais orbita (D. orbita) are of interest for their anti-inflammatory properties. This study evaluates the binding mechanism and potentiality of several brominated indoles (tyrindoxyl sulfate, tyrindoleninone, 6-bromoisatin, and 6,6′-dibromoindirubin) against inflammatory mediators cyclooxygenases-1/2 (COX-1/2) using molecular docking, followed by molecular dynamics simulation, along with physicochemical, drug-likeness, pharmacokinetic (pk), and toxicokinetic (tk) properties. Molecular docking identified that these indole compounds are anchored, with the main amino acid residues, positioned in the binding pocket of the COX-1/2, required for selective inhibition. Moreover, the molecular dynamics simulation based on root mean square deviation (RMSD), radius of gyration (Rg), solvent accessible surface area (SASA), and root mean square fluctuation (RMSF) analyses showed that these natural brominated molecules transit rapidly to a progressive constant configuration during binding with COX-1/2 and seem to accomplish a consistent dynamic behavior by maintaining conformational stability and compactness. The results were comparable to the Food and Drug Administration (FDA)-approved selective COX inhibitor, aspirin. Furthermore, the free energy of binding for the compounds assessed by molecular mechanics–Poisson–Boltzmann surface area (MM–PBSA) confirmed the binding capacity of indoles towards COX-1/2, with suitable binding energy values except for the polar precursor tyrindoxyl sulfate (with COX-1). The physicochemical and drug-likeness analysis showed zero violations of Lipinski’s rule, and the compounds are predicted to have excellent pharmacokinetic profiles. These indoles are projected to be non-mutagenic and free from hepatotoxicity, with no inhibition of human ether-a-go–go gene (hERG) I inhibitors, and the oral acute toxicity LD₅₀ in rats is predicted to be similar or lower than aspirin. Overall, this work has identified a plausible mechanism for selective COX inhibition by natural marine indoles as potential therapeutic candidates for the mitigation of inflammation.

Carcinogenesis: Failure of resolution of inflammation?

Inflammation in the tumor microenvironment is a hallmark of cancer and is recognized as a key characteristic of carcinogens. However, the failure of resolution of inflammation in cancer is only recently being understood. Products of arachidonic acid and related fatty acid metabolism called eicosanoids, including prostaglandins, leukotrienes, lipoxins, and epoxyeicosanoids, critically regulate inflammation, as well as its resolution. The resolution of inflammation is now appreciated to be an active biochemical process regulated by endogenous specialized pro-resolving lipid autacoid mediators which combat infections and stimulate tissue repair/regeneration. Environmental and chemical human carcinogens, including aflatoxins, asbestos, nitrosamines, alcohol, and tobacco, induce tumor-promoting inflammation and can disrupt the resolution of inflammation contributing to a devastating global cancer burden. While mechanisms of carcinogenesis have focused on genotoxic activity to induce mutations, nongenotoxic mechanisms such as inflammation and oxidative stress promote genotoxicity, proliferation, and mutations. Moreover, carcinogens initiate oxidative stress to synergize with inflammation and DNA damage to fuel a vicious feedback loop of cell death, tissue damage, and carcinogenesis. In contrast, stimulation of resolution of inflammation may prevent carcinogenesis by clearance of cellular debris via macrophage phagocytosis and inhibition of an eicosanoid/cytokine storm of pro-inflammatory mediators. Controlling the host inflammatory response and its resolution in carcinogen-induced cancers will be critical to reducing carcinogen-induced morbidity and mortality. Here we review the recent evidence that stimulation of resolution of inflammation, including pro-resolution lipid mediators and soluble epoxide hydrolase inhibitors, may be a new chemopreventive approach to prevent carcinogen-induced cancer that should be evaluated in humans.

Fatty Acid Mediators in the Tumor Microenvironment

Patients with cancer frequently overexpress inflammatory cytokines with an associated neutrophilia both of which may be downregulated by diets with high omega-3 polyunsaturated fatty acids (ω-3 PUFA). The anti-inflammatory activity of dietary ω-3 PUFA has been suggested to have anticancer properties and to improve survival of cancer patients. Currently, the majority of dietary research efforts do not differentiate between obesity and dietary fatty acid consumption as mediators of inflammatory cell expansion and tumor microenvironmental infiltration, initiation, and progression. In this chapter, we discuss the relationships between dietary lipids, inflammation, neoplasia and strategies to regulate these relationships. We posit that dietary composition, notably the ratio of ω-3 vs. ω-6 PUFA, regulates tumor initiation and progression and the frequency and sites of metastasis that, together, impact overall survival (OS). We focus on three broad topics: first, the role of dietary lipids in chronic inflammation and tumor initiation, progression, and regression; second, lipid mediators linking inflammation and cancer; and third, dietary lipid regulation of murine and human tumor initiation, progression, and metastasis.

Aspirin-triggered proresolving mediators stimulate resolution in cancer

Inflammation in the tumor microenvironment is a strong promoter of tumor growth. Substantial epidemiologic evidence suggests that aspirin, which suppresses inflammation, reduces the risk of cancer. The mechanism by which aspirin inhibits cancer has remained unclear, and toxicity has limited its clinical use. Aspirin not only blocks the biosynthesis of prostaglandins, but also stimulates the endogenous production of anti-inflammatory and proresolving mediators termed aspirin-triggered specialized proresolving mediators (AT-SPMs), such as aspirin-triggered resolvins (AT-RvDs) and lipoxins (AT-LXs). Using genetic and pharmacologic manipulation of a proresolving receptor, we demonstrate that AT-RvDs mediate the antitumor activity of aspirin. Moreover, treatment of mice with AT-RvDs (e.g., AT-RvD1 and AT-RvD3) or AT-LXA₄ inhibited primary tumor growth by enhancing macrophage phagocytosis of tumor cell debris and counter-regulating macrophage-secreted proinflammatory cytokines, including migration inhibitory factor, plasminogen activator inhibitor-1, and C-C motif chemokine ligand 2/monocyte chemoattractant protein 1. Thus, the pro-resolution activity of AT-resolvins and AT-lipoxins may explain some of aspirin's broad anticancer activity. These AT-SPMs are active at considerably lower concentrations than aspirin, and thus may provide a nontoxic approach to harnessing aspirin's anticancer activity.

Hypoxia inducible factor-1α: Its role in colorectal carcinogenesis and metastasis

Tumor growth creates a hypoxic microenvironment, which promotes angiogenesis and aggressive tumor growth and invasion. HIF1α is a central molecule involved in mediating these effects of hypoxia. In colorectal cancer (CRC), hypoxia stabilizes the transcription factor HIF1α, leading to the expression of genes that are involved in tumor vascularization, metastasis/migration, cell survival and chemo-resistance. Therefore, HIF1α is a rational target for the development of new therapeutics for CRC. This article reviews the central role of HIF1α in CRC angiogenesis, metastasis, and progression as well as the strategies to target HIF1α stabilization.

2-(2-Arylphenyl)benzoxazole As a Novel Anti-Inflammatory Scaffold: Synthesis and Biological Evaluation

The 2-(2-arylphenyl)benzoxazole moiety has been found to be a new and selective ligand for the enzyme cyclooxygenase-2 (COX-2). The 2-(2-arylphenyl)benzoxazoles 3a-m have been synthesized by Suzuki reaction of 2-(2-bromophenyl)benzoxazole. Further synthetic manipulation of 3f and 3i led to 3o and 3n, respectively. The compounds 3g, 3n, and 3o selectively inhibited COX-2 with selectivity index of 3n much better than that of the COX-2 selective NSAID celecoxib. The in vivo anti-inflammatory potency of 3g and 3n is comparable to that of celecoxib and the nonselective NSAID diclofenac at two different doses, and 3o showed better potency compared to these clinically used NSAIDs.

An apple oligogalactan potentiates the growth inhibitory effect of celecoxib on colorectal cancer

Multiple studies have indicated that selective cyclooxygenase-2 (COX-2) inhibitors possess clinically chemopreventive and preclinically anticancer activities. Their long-term use, however, may be limited by the cardiovascular toxicity. This study tried to investigate whether an apple oligogalactan (AOG) could enhance the growth inhibitory effect of celecoxib on colorectal cancer. Caco-2 and HT-29 cell lines were exposed to different concentrations of AOG (0-1 g/L), celecoxib (0-25 μmol/L), and their combination. COX-2 levels were assessed by reverse transcription PCR and Western blot. COX-2 activity was evaluated by measuring prostaglandin E2 concentration. A colitis-associated colorectal cancer (CACC) mouse model was used to determine the effect of the combination in vivo. AOG (0.1-0.5 g/L) could potentiate the inhibitory effect of physiologic doses of celecoxib (5 μmol/L) on cell growth and decrease COX-2 expressions both at RNA and protein levels. In vivo, the combination (2.5% AOG plus 0.04% celecoxib, w/w) prevented against CACC in mice effectively. Our data indicate that AOG could potentiate the growth inhibitory effect of celecoxib on colorectal cancer both in vitro and in vivo through influencing the expression and function of COX-2 and phosphorylation of MAPKs, which suggests a new possible combinatorial strategy in colorectal cancer therapy.

Identification of novel compounds that enhance colon cancer cell sensitivity to inflammatory apoptotic ligands

Immune and inflammatory death ligands expressed within neoplastic tissue could potentially target apoptosis to transformed cells. To develop approaches that accentuate the anti-cancer potential of the inflammatory response, the Chembridge DIVERSet (TM) library was screened for compounds that accentuated apoptosis in a strictly TNF-dependent manner. We identified a number of novel compounds with this activity, the most active of these, AK3 and AK10, sensitized colon cancer cells to TNF at 0.5 μM and 2 μM, respectively, without inducing apoptosis on their own. The activity of these compounds was structure-dependent and general, as they accentuated cell death by TNF or Fas ligation in multiple colon cancer cell lines. Both AK3 and AK10 arrested cells in mitosis, with live cell imaging indicating that mitotically arrested cells were the source of apoptotic bodies. AK3 accentuated caspase-8 and caspase-9 activation with little effect on NFκB target gene activation. Enhanced caspase activation corresponded to an increased expression of TNFR1 on the cell surface. To determine the general interplay between mitotic arrest and TNF sensitivity, Aurora kinase (MLN8054 and MLN8237) and PLK1 (BI2536) inhibitors were tested for their ability to sensitize cells to TNF. PLK1 inhibition was particularly effective and influenced TNFR1 surface presentation and caspase cleavage like AK3, even though it arrested mitosis at an earlier stage. We propose that AK3 and AK10 represent a new class of mitotic inhibitor and that selected mitotic inhibitors may be useful for treating colon cancers or earlier lesions that have a high level of inflammatory cell infiltrate.

Cumulative risk of colon cancer up to age 70 years by risk factor status using data from the Nurses' Health Study

The authors developed a comprehensive model of colon cancer incidence that allows for nonproportional hazards and accounts for the temporal nature of risk factors. They estimated relative risk based on cumulative incidence of colon cancer by age 70 years. Using multivariate, nonlinear Poisson regression, they determined colon cancer risk among 83,767 participants in the Nurses' Health Study. The authors observed 701 cases of colon cancer between 1980 and June 1, 2004. There was increased risk for a positive family history of colon or rectal cancer (55%), 10 or more pack-years of cigarette smoking before age 30 years (16%), and tallness (67 inches (170 cm) vs. 61 inches (155 cm): 19%). Reduced risk was observed for current postmenopausal hormone use (-23%), being physically active (21 metabolic equivalent (MET)-hours/week vs. 2 MET-hours/week: -49%), taking aspirin (7 tablets/week vs. none: -29%), and being screened (-24%). Women who smoked, had a consistently high relative weight, had a low physical activity level, consumed red or processed meat daily, were never screened, and consumed low daily amounts of folate had almost a 4-fold higher cumulative risk of colon cancer by age 70 years. For women with a high risk factor profile, adopting a healthier lifestyle could dramatically reduce colon cancer risk.

Effects of cotreatment of 12-O-tetradecanoylphorbol-13-acetate and H2O2 on apoptotic regulation via AMP-activated protein kinase-cyclooxygenase-2 signals

Colorectal cancer displays elevated cyclooxygenase-2 (COX-2) expression, and several studies have suggested that COX-2 expression is associated with parameters of aggressive colon cancer. AMP-activated protein kinase (AMPK) is a sensor of cellular energy status, and recent studies indicate that AMPK activation strongly suppresses cell proliferation in nonmalignant cells as well as in tumor cells. As a metabolic sensing signal, AMPK is involved in cancer cell apoptosis. In HT-29 colon cancer cells, the regulation of COX-2 expression by treating with TPA (12-O-tetradecanoylphorbol-13-acetate), low-level H(2)O(2), high-level H(2)O(2), and finally the combinations of TPA and low H(2)O(2) or high H(2)O(2) was investigated. We found that COX-2 expression levels with treatment reacted as follows: with TPA alone > TPA and low H(2)O(2) > low H(2)O(2) > high H(2)O(2) > TPA and high H(2)O(2). COX-2 regulation by these agents was accompanied by the alteration of AMPK control. The apoptotic bodies were detected as follows: high level of H(2)O(2) > TPA > low level of H(2)O(2). The present findings suggest that both COX-2 stimulators (TPA and H(2)O(2)) might have differential effects on COX-2 and AMPK regulation and further apoptotic regulation.

Characterization of the interaction between fenamates and hippocampal neuron GABA(A) receptors

Fenamate NSAIDs have several central effects, including anti-epileptic and neuroprotective actions. The underlying mechanism(s) of these actions are not presently understood. In this study, the effects of five members of the fenamate NSAID group were investigated on native ligand-gated ion channels expressed in cultured rat hippocampal neurons. All fenamates tested (1-100 microM) dose-dependently potentiated GABA-evoked currents; mefenamic acid (MFA) was the most potent and efficacious and was found to shift the GABA dose-response curve to the left without effect on the maximum amplitude or the GABA Hill Slope. The modulation of GABA receptors by MFA was not reduced in the presence of the benzodiazepine antagonist, flumazenil (10 microM) and was moderately voltage-dependent. MFA at concentrations >or=10 microM evoked dose-dependent currents in the absence of GABA. These currents were potentiated by diazepam (1 microM) and blocked by bicuculline (10 microM). The MFA (50 microM) current-voltage relationship and reversal potential were similar to that evoked by GABA. MFA (1-100 microM) had no effects on sub-maximal glycine, glutamate or NMDA evoked currents. These data show that fenamate NSAIDs are a highly effective class of GABA(A) receptor modulator and activators.

Down-regulation of PGE2 by physiologic levels of celecoxib is not sufficient to induce apoptosis or inhibit cell proliferation in human colon carcinoma cell lines

This study was performed to evaluate whether down-regulation of prostaglandin E(2) (PGE(2)) synthesis by celecoxib treatment is associated with inhibition of cell growth in human colon carcinoma cell lines. Physiologic concentrations of celecoxib (5-10 microM) inhibited 80% to 90% of PGE(2) production in HT-29 cells that express high levels of COX-2 protein. In these concentrations, celecoxib had a minor inhibitory effect (20-30%) on cell growth. There was a significant change in induction of apoptosis only at higher concentrations of celecoxib (>20 microM). Treatment by low concentrations of celecoxib did not alter the levels of COX-1, beta-catenin, P(27), Bcl-2, and Bcl-x proteins. The effect of celecoxib on cell growth inhibition was higher on the COX-2-positive HT-29 cell line (IC(50)=20 microM) than on the COX-2 deficient SW-480 cell line (IC(50)=35 microM). In conclusion, inhibition of PGE(2) synthesis is an early, but not sufficient, step in the mechanism of celecoxib-mediated cell growth inhibition. These results support the need for additional evaluation of independent COX-2 pathways of celecoxib in chemoprevention of CRC.

Survivin depletion preferentially reduces the survival of activated K-Ras-transformed cells

To identify cancer-specific targets, we have conducted a synthetic lethal screen using a small interfering RNA (siRNA) library targeting ∼4,000 individual genes for enhanced killing in the DLD-1 colon carcinoma cell line that expresses an activated copy of the K-Ras oncogene. We found that siRNAs targeting baculoviral inhibitor of apoptosis repeat-containing 5 (survivin) significantly reduced the survival of activated K-Ras-transformed cells compared with its normal isogenic counterpart in which the mutant K-Ras gene had been disrupted (DKS-8). In addition, survivin siRNA induced a transient G2-M arrest and marked polyploidy that was associated with increased caspase-3 activation in the activated K-Ras cells. These results indicate that tumors expressing the activated K-Ras oncogene may be particularly sensitive to inhibitors of the survivin protein. [Mol Cancer Ther 2007;6(1):269–76]

FOLFIRI with or without celecoxib in advanced colorectal cancer: a randomized phase II study of the Gruppo Oncologico dell'Italia Meridionale (GOIM)

BACKGROUND

The aim of the study was to verify the efficacy and safety of the addition of celecoxib to FOLFIRI combination therapy in patients affected by advanced colorectal cancer.

PATIENTS AND METHODS

Eighty-one chemotherapy-naïve patients entered in this randomized phase II trial of the GOIM (protocol no. 2301). Patients were randomized to receive FOLFIRI regimen (arm A): irinotecan 180 mg/m(2) on day 1 with LV5FU2 regimen (LV at 100 mg/m(2) administered as a 2-h infusion before FU at 400 mg/m(2) as an intravenous bolus injection, and FU at 600 mg/m(2) as a 22-h infusion immediately after 5-FU bolus injection on day 1 and 2); or FOLFIRI plus celecoxib 400 mg twice daily for 14 days (arm B). Both treatments were repeated every 2 weeks.

RESULTS

Seventy-seven patients (38 in arm A and 39 in arm B) were evaluable for response. The overall response rate was 41% in arm A (95% CI 27% to 57%) and 35% in arm B (95% CI 20% to 50%). When only assessable patients were analyzed, overall response rate was 45% in arm A (95% CI 29% to 61%) and 36% in arm B (95% CI 21% to 51%). Median time to progression, median duration of response and survival were, respectively, 8 months, 9 months and 16 months in arm A, and 7 months, 9 months and 19 months in arm B. All patients were evaluable for toxicity, which was globally mild in both arms; grade 3-4 toxicity was uncommon, and gastrointestinal disturbances were the most common.

CONCLUSIONS

FOLFIRI regimen is effective and well-tolerated as a first-line treatment in patients with advanced colorectal cancer. The addition of celecoxib to FOLFIRI regimen does not improve results.

Genetic polymorphisms of flavin monooxygenase 3 in sulindac-induced regression of colorectal adenomas in familial adenomatous polyposis

Sulindac is a nonsteroidal antiinflammatory drug with a chemopreventive effect in patients with familial adenomatous polyposis (FAP). In vivo, the active form of sulindac is sulindac sulfide, which is inactivated by the hepatic microsomal enzyme, flavin monooxygenase 3 (FMO3). In humans, numerous polymorphisms exist in FMO3, which alter enzymatic activity and subsequent substrate metabolism. We recently showed that certain polymorphic forms of FMO3 with reduced activity were associated with a more favorable response to sulindac in preventing the formation of adenomas in patients with FAP without polyps at baseline. Here, we determined whether these FMO3 polymorphisms correlated with the ability of sulindac to regress polyposis in patients with FAP who had polyps prior to treatment. Nineteen patients were treated with 150 mg sulindac twice a day for 6 months. The size and number of polyps in each patient was assessed at baseline (prior to the administration of sulindac), and at 3 and 6 months. Genotyping was done on seven established FMO3 polymorphisms with functional significance-M66I, E158K, P153L, V257M, E305X, E308G, and R492W. Statistical analyses were done with Wilcoxon rank sum test. Of the loci examined, only E158K and E308G showed polymorphic changes. Six patients exhibited polymorphisms in both E158K and E308G loci and were designated as genotype combination 1. The remaining patients were designated as genotype combination 2. Over the course of treatment, patients with genotype combination 1 had a greater reduction in both the size and number of polyps than those with genotype combination 2. These results suggest that combined polymorphic changes in the E158K and E308G alleles may protect against polyposis in patients with FAP treated with sulindac.

Nonsteroidal anti-inflammatory drugs and the risk of actinic keratoses and squamous cell cancers of the skin

BACKGROUND

Although animal studies suggest that nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin, may protect against cutaneous squamous cell carcinoma (SCC) and actinic keratoses (AKs), possible effects on keratinocytic cancers in humans are unknown.

OBJECTIVE

We sought to examine the relationship between ingestion of NSAIDs and the risk of SCC and AKs in humans.

METHODS

We conducted a case-control study nested within a community-based cohort of 1621 people in southern Queensland, Australia. Eighty-six persons with SCC were compared with 187 age- and sex-matched control subjects randomly selected from within the cohort. NSAID use was captured through face-to-face interviews with study participants, supplemented by color photographs of product packaging. We defined regular use of NSAIDs as consumption of at least two tablets per week (low frequency) or at least 8 tablets per week (high frequency) for at least 1 year. AKs were counted on the face, ears, right hand, and right forearm by a single physician.

RESULTS

Patients with SCC were significantly less likely than control subjects to have used any NSAIDs 8 or more times per week for more than 1 year (multivariate odds ratio [OR] 0.07, 95% confidence interval [CI] 0.01-0.71) and to have used full-dose NSAIDs 2 or more times per week for more than 5 years (OR, 0.20; 95% CI, 0.04-0. 96). Among participants without SCC, current regular users of NSAIDs (> or =2 times per week) had significantly lower counts of AKs than nonusers (rate ratio [RR], 0.52; 95% CI, 0.30-0.91).

LIMITATIONS

Estimates of NSAID use were based on self-reported data. Statistical power to detect associations was limited by the number of cases with SCC.

CONCLUSION

Regular users of NSAIDs appear to have lower risks of SCC and lower counts of AKs than nonusers.

Celecoxib and curcumin synergistically inhibit the growth of colorectal cancer cells

PURPOSE

Multiple studies have indicated that cyclooxygenase-2 (COX-2) inhibitors may prevent colon cancer, which is one of the leading causes of cancer death in the western world. Recent studies, however, showed that their long-term use may be limited due to cardiovascular toxicity. This study aims to investigate whether curcumin potentiates the growth inhibitory effect of celecoxib, a specific COX-2 inhibitor, in human colon cancer cells.

EXPERIMENTAL DESIGN

HT-29 and IEC-18-K-ras (expressing high levels of COX-2), Caco-2 (expressing low level of COX-2), and SW-480 (no expression of COX-2) cell lines were exposed to different concentrations of celecoxib (0-50 micromol/L), curcumin (0-20 micromol/L), and their combination. COX-2 activity was assessed by measuring prostaglandin E(2) production by enzyme-linked immunoassay. COX-2 mRNA levels were assessed by reverse transcription-PCR.

RESULTS

Exposure to curcumin (10-15 micromol/L) and physiologic doses of celecoxib (5 micromol/L) resulted in a synergistic inhibitory effect on cell growth. Growth inhibition was associated with inhibition of proliferation and induction of apoptosis. Curcumin augmented celecoxib inhibition of prostaglandin E(2) synthesis. The drugs synergistically down-regulated COX-2 mRNA expression. Western blot analysis showed that the level of COX-1 was not altered by treatment with celecoxib, curcumin, or their combination.

CONCLUSIONS

Curcumin potentiates the growth inhibitory effect of celecoxib by shifting the dose-response curve to the left. The synergistic growth inhibitory effect was mediated through a mechanism that probably involves inhibition of the COX-2 pathway and may involve other non-COX-2 pathways. This synergistic effect is clinically important because it can be achieved in the serum of patients receiving standard anti-inflammatory or antineoplastic dosages of celecoxib.

Heparin-binding epidermal growth factor-like growth factor inhibits cytokine-induced NF-kappa B activation and nitric oxide production via activation of the phosphatidylinositol 3-kinase pathway

NO produced by inducible NO synthase (iNOS) has been implicated in various pathophysiological processes including inflammation. Therefore, inhibitors of NO synthesis or iNOS gene expression have been considered as potential anti-inflammatory agents. We have previously demonstrated that heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF) decreases proinflammatory cytokine IL-8 and NO production in cytokine-stimulated intestinal epithelial cells by interfering with the NF-kappaB signaling pathway. However, the upstream signaling mechanisms involved in these responses have not yet been defined. In this report, we show that in intestinal epithelial cells, HB-EGF triggered PI3K-dependent phosphorylation of Akt. Inhibition of PI3K reversed the ability of HB-EGF to block NF-kappaB activation, expression of iNOS, and NO production. Small interfering RNA of PI3K also reversed the inhibitory effect of HB-EGF on iNOS expression. Alternatively, transient expression of constitutively active PI3K decreased NO production by approximately 2-fold more than treatment with HB-EGF alone. This PI3K effect was HB-EGF dependent. Thus, activation of PI3K is essential but not sufficient for decreased NO synthesis. PI3K and HB-EGF act synergistically to decrease NO synthesis. Neither overexpression or inhibition of MEK, Ras, or Akt affected HB-EGF-mediated inhibition of NF-kappaB activation. These data demonstrate that HB-EGF decreases proinflammatory cytokine-stimulated NF-kappaB activation and NO production via activation of the PI3K signaling pathway. These results also suggest that inhibition of NF-kappaB and activation of the PI3K-dependent signaling cascade by HB-EGF may represent key signals responsible for the anti-inflammatory effects of HB-EGF.

Heat shock proteins: new keys to the development of cytoprotective therapies

All cells, from bacterial to human, have a common, intricate response to stress that protects them from injury. Heat shock proteins (Hsps), also known as stress proteins and molecular chaperones, play a central role in protecting cellular homeostatic processes from environmental and physiologic insult by preserving the structure of normal proteins and repairing or removing damaged ones. An understanding of the interplay between Hsps and cell stress tolerance will provide new tools for treatment and drug design that maximise preservation or restoration of health. For example, the increased vulnerability of tissues to injury in some conditions, such as ageing, diabetes mellitus and menopause, or with the use of certain drugs,, such as some antihypertensive medications, is associated with an impaired Hsp response. Additionally, diseases that are associated with tissue oxidation, free radical formation, disorders of protein folding, or inflammation, may be improved therapeutically by elevated expression of Hsps. The accumulation of Hsps, whether induced physiologically, pharmacologically, genetically, or by direct administration of the proteins, is known to protect the organism from a great variety of pathological conditions, including myocardial infarction, stroke, sepsis, viral infection, trauma, neurodegenerative diseases, retinal damage, congestive heart failure, arthritis, sunburn, colitis, gastric ulcer, diabetic complications and transplanted organ failure. Conversely, lowering Hsps in cancer tissues can amplify the effectiveness of chemo- or radiotherapy. Treatments and agents that induce Hsps include hyperthermia, heavy metals (zinc and tin), salicylates, dexamethasone, cocaine, nicotine, alcohol, alpha-adrenergic agonists, PPAR-gamma agonists, bimoclomol, geldanamycin, geranylgeranylacetone and cyclopentenone prostanoids. Compounds that suppress Hsps include quercetin (a bioflavinoid), 15-deoxyspergualin (an immunosuppressive agent) and retinoic acid. Researchers who are cognisant of the Hsp-related effects of these and other agents will be able to use them to develop new therapeutic paradigms.

Role of Helicobacter pylori eradication in aspirin or non-steroidal anti-inflammatory drug users

Helicobacter pylori (H pylori) infection and the use of non-steroidal anti-inflammatory drugs (NSAIDs) including aspirin at any dosage and formulation represent well-established risk factors for the development of uncomplicated and complicated peptic ulcer disease accounting for the majority of such cases. Although the interaction between H pylori and NSAID/aspirin use in the same individuals was questioned in some epidemiological studies, it has now become widely accepted that they are at least independent risk factors for peptic ulcer disease. According to data from randomized intervention trials, naive NSAID users certainly benefit from testing for H pylori infection and, if positive, H pylori eradication therapy prior to the initiation of NSAID. A similar strategy is also suggested for naive aspirin users, although the efficacy of such an approach has not been evaluated yet. Strong data also support that chronic aspirin users with a recent ulcer complication should be tested for H pylori infection and, if positive, receive H pylori eradication therapy after ulcer healing, while they appear to benefit from additional long-term therapy with a proton pump inhibitor (PPI). A similar approach is often recommended to chronic aspirin users at a high risk of ulcer complication. H pylori eradication alone does not efficiently protect chronic NSAID users with a recent ulcer complication or those at a high-risk, who certainly should be treated with long-term PPI therapy, but H pylori eradication may be additionally offered even in this setting. In contrast, testing for H pylori or PPI therapy is not recommended for chronic NSAID/aspirin users with no ulcer complications or those at a low risk of complications.

Long Term Prognosis in Patients with Peripheral Arterial Disease Treated with Antiplatelet Agents

OBJECTIVE

To determine the fatal and non-fatal cardiovascular event rate in patients with intermittent claudication treated with antiplatelet agents.

METHODS AND DESIGN

Patients with PAD-II stage Fontaine (n=223) and sex and age matched controls (n=446) were followed up from 1974 to 1998. All patients were treated with antiplatelet agents (aspirin, 325 mg once daily or ticlopidine, 250 mg twice daily) and for risk factors, if present. The end points were death for any cause (vascular event, cancer, and others) and non-fatal vascular events (myocardial infarction, ischemic/hemorrhagic stroke, and leg amputation).

RESULTS

PAD patients had a significantly higher mortality rate than controls (3.99 vs. 2.53 deaths for 100 patients per year, respectively), cancer (mostly lung, stomach and colon) and vascular mortality accounted for such difference. The incidence of non-fatal vascular events was three times higher in patients than in controls (1.7 vs. 0.56, 100 patients per year, respectively, p<0.05) even considering amputation separately (0.28 vs. 0.00, 100 patients per year, p<0.05). No difference between patients treated with aspirin or ticlopidine could be found in both end points.

CONCLUSIONS

Vascular mortality and morbidity, despite the use of antiplatelet agents, are still higher than sex and age matched controls; however, the commonest cause of death is cancer.

Nimesulide inhibits proliferation via induction of apoptosis and cell cycle arrest in human gastric adenocarcinoma cell line

AIM

To evaluate the potential role of Nimesulide, a selective COX-2 inhibitor, in proliferation and apoptosis of gastric adenocarcinoma cells SGC7901.

METHODS

Cell counts and MTT assay were used to quantify the influence of Nimesulide in the proliferation of SGC7901 cells. Transmission electron microscopy and flow cytometry were used to observe the induction of Nimesulide the apoptosis of SGC7901 cells and influence in the distribution of cell cycle. The expression of P27(kip1) protein was observed by immunocytochemical staining.

RESULTS

SGC-7901 Cells treated with Nimesulide at various concentrations exhibited a profound dose- and time-dependent reduction in the proliferation rate over the 72 h test period. The highest survival rate of the cells was 78.7 %, but the lowest being 22.7 %. Nimesulide induced apoptosis of the cells in a dose-dependent and non-linear manner and increased the proportion of cells in the G(0)/G(1) phase and decreased the proportion in the S and G(2)/M phase of the cell cycle. Meanwhile, Nimesulide could up-regulate the expression of P27(kip1) protein.

CONCLUSION

The induction of apoptosis and cell cycle arrest are both anti-proliferative responses that likely contribute to the antineoplastic action of nimesulide on SGC-7901 cells. The up-regulation of P27(kip1) gene may contribute to the accumulation of these cells in the G(0)/G(1) phase following treatment with Nimesulide. Selective COX-2 inhibitor may be a new channel of the chemoprevention and chemotherapy for gastric carcinoma.

Physical exercise, use of Plantago ovata and aspirin, and reduced risk of colon cancer

To evaluate certain risk and protective factors for colon cancer in our population, we conducted a paired case-control study where cases were all people diagnosed with colon cancer who were registered at the Cancer Data Exchange Systems of the Community of Madrid between January 1995 and December 1996, and controls were randomly taken from electoral lists. The study population consisted of 424 persons. Using SPSS for Windows, variables were adjusted by multiple logistic regression. The results indicate that lack of physical exercise is associated with an increased risk of colon cancer, with an odds ratio (OR) of 2.8 (95% confidence interval (CI) 1.28-6.21) as compared with moderate activity 1-2 days a week. The risk decreases linearly with increasing physical exercise, and this association remains after stratifying the analysis for the existence of constipation. The consumption of is associated with a reduced risk of colon cancer in constipated patients, with an OR of 0.094 (0.014-0.639), as is aspirin use, with an OR of 0.980 (0.898-0.999). These results were obtained after adjusting all the ORs for diet, smoking, alcohol consumption, family history and socio-demographic factors such as marital status and educational level.

Primary prevention: phytoprevention and chemoprevention of colorectal cancer

Considering the various stages of carcinogenesis and the numerous tumor types and available chemoprevention agents, knowledge of the etiology and the type of cancer to be treated, or possibly prevented, and understanding of the mechanisms by which agents exert their chemoprevention benefits may provide for improved strategy in designing therapeutic regimens. Because cancer usually develops over a 10- to 20-year period, it may be necessary for some agents to be provided before or early in the initiation steps of carcinogenesis to have beneficial effects. On the other hand, some agents may be more suitable for CRC prevention if provided at a later stage of carcinogenesis. Gene array, genomics, and proteomics are useful tools in advancing our understanding of the molecular events involved in carcinogenesis and in identifying markers of risk and surrogate end-points for colorectal cancer progression. These techniques may also serve for screening, identifying, and providing treatment targets for high-risk patients populations. Treatment could be developed depending on a patient's individual needs and genomic tumor profile. Clinical markers and surrogate end-points should be considered, together with molecular measurements, to more accurately assess risk. NSAIDs and COXIBs are clinically recognized as chemoprevention agents, and clinical trials evaluating their efficacy are ongoing. Treatment protocols, including dose and timing, remain to be determined, however. DFMO may best be used in combination with other chemoprevention agents. Dietary fiber and calcium supplements, as part of an overall low-fat diet, may decrease CRC risk. Long-term compliance with this regimen may be necessary to effect a beneficial outcome. Folate holds promise but needs further investigation, especially because its beneficial effects may depend on cancer type. Phytochemicals have been identified as strong candidates for use as agents to prevent colorectal cancer in cell culture and in rodent models of carcinogenesis. Their potential as chemoprevention agents must be demonstrated in clinical trials. In vitro and animal studies indicated that combination therapy may be a promising strategy over the monotherapy approach; clinical trials addressing the safety and efficacy of some combinations (DFMO/sulindac, fiber/calcium) are underway. The gastrointestinal tract and other organs are constantly exposed to a mixture of potentially toxic compounds and molecules considered favorable to health. Homeostasis between stress-mediated by toxic compounds and defensive mechanisms, is key for the maintenance of health and the prevention of disease. Whereas aggressive pharmacologic treatment may be necessary for patients at high risk for cancer, dietary supplements may be useful for populations at normal risk. The message for cancer prevention in the general population may well remain: keep a balanced healthy diet, eating a variety from all food groups, as part of a healthy lifestyle that includes moderate exercise.

Nationwide study of cancer risk among hip replacement patients in Sweden

BACKGROUND

Orthopedic implants and their fixatives contain materials with carcinogenic potential. Whether these implants are linked to subsequent cancer development remains unknown, mainly because large-scale, long-term follow-up data are scarce.

METHODS

We conducted a nationwide cohort study in Sweden to examine cancer incidence among 116,727 patients who underwent hip replacement surgery during the period from 1965 through 1994. Through record linkage to the Swedish Cancer Register, we identified all incident cancers through 1995 in this population (693,954 person-years of observation). For each cancer type, the observed number of cases was divided by that expected in the general Swedish population to produce standardized incidence ratios (SIRs).

RESULTS

Relative to the general population, the cohort had no overall cancer excess (SIR = 1.01; 95% confidence interval [CI] = 0.99 to 1.03). However, we observed elevated SIRs for prostate cancer (SIR = 1.16; 95% CI = 1.11 to 1.22) and melanoma (SIR = 1.15; 95% CI = 1.01 to 1.30) and a reduction in stomach cancer risk (SIR = 0.83; 95% CI = 0.75 to 0.92). Long-term follow-up (>or=15 years) revealed an excess of multiple myeloma (SIR = 1.86; 95% CI = 1.01 to 3.11) and a statistically nonsignificant increase in bladder cancer (SIR = 1.42; 95% CI = 0.98 to 1.99). There was no material increase in risk for bone or connective tissue cancer for either men or women in any follow-up period.

CONCLUSIONS

In this, the largest study to date, hip implant patients had similar rates of most types of cancer to those in the general population. Although the excesses of melanoma, multiple myeloma, and prostate and bladder cancers may be due to chance, confounding, or detection bias and should be interpreted cautiously, they warrant further investigation because of the ever-increasing use of hip implants at younger ages.