Inhibition of human colon cancer cell growth by selective inhibition of cyclooxygenase-2

Infectious causes of colorectal cancer

Colorectal cancer is a major cause of cancer-related morbidity and mortality in the United States and many other regions of the world. Our understanding of the pathogenesis of colorectal cancer, from the precursor adenomatous polyp to adenocarcinoma, has evolved rapidly. Colorectal carcinogenesis is a sequential process characterized by the accumulation of multiple genetic and molecular alterations in colonic epithelial cells. However, the development of colorectal cancer involves more then just a genetic predisposition. External or environmental factors presumably play a significant role, and inflammatory bowel diseases, obesity, alcohol consumption, and a diet high in fat and low in fiber have all been implicated as risk factors for the development of either colonic adenomas or carcinomas. We are becoming increasingly aware of microbes as causes of malignancies. This article reviews the various microbes that have been associated with the development of colorectal carcinomas.

The MIF homologue D-dopachrome tautomerase promotes COX-2 expression through β-catenin-dependent and -independent mechanisms

The cytokine/growth factor, macrophage migration inhibitory factor (MIF), contributes to pathologies associated with immune, inflammatory, and neoplastic disease processes. Several studies have shown an important contributing role for MIF-dependent COX-2 expression in the progression of these disorders. We now report that the MIF homologue, D-dopachrome tautomerase (D-DT), is both sufficient and necessary for maximal COX-2 expression in colorectal adenocarcinoma cell lines. D-DT-dependent COX-2 transcription is mediated in part by β-catenin protein stabilization and subsequent transcription. Also contributing to D-DTs regulation of COX-2 expression are the activities of both c-jun-N-terminal kinase and the MIF-interacting protein, Jab1/CSN5. Interestingly, D-DT-dependent β-catenin stabilization is regulated by COX-2 expression, suggesting the existence of an amplification loop between COX-2- and β-catenin-mediated transcription in these cells. Because both COX-2- and β-catenin-mediated transcription are important contributors to colorectal cancer (CRC) disease maintenance and progression, these findings suggest a unique and novel regulatory role for MIF family members in CRC pathogenesis.

Combined treatment with the Cox-2 inhibitor niflumic acid and PPARγ ligand ciglitazone induces ER stress/caspase-8-mediated apoptosis in human lung cancer cells

The present study was performed to investigate the possible combined use of the Cox-2 inhibitor niflumic acid and the PPARγ ligand ciglitazone and to elucidate the mechanisms underlying enhanced apoptosis by this combination treatment in human lung cancer cells. Combined niflumic acid-ciglitazone treatment synergistically induced apoptotic cell death, activated caspase-9, caspase-3, and induced caspase-3-mediated PARP cleavage. The combination treatment also triggered apoptosis through caspase-8/Bid/Bax activation, and the inhibition of caspase-8 suppressed caspase-8/Bid activation, caspase-3-mediated PARP cleavage, and concomitant apoptosis. In addition, combined niflumic acid-ciglitazone treatment significantly induced ER stress responses, and suppression of CHOP expression significantly attenuated the combined niflumic acid-ciglitazone treatment-induced activation of caspase-8 and caspase-3, and the subsequent apoptotic cell death, indicating a role of ER stress in caspase-8 activation and apoptosis. Interestingly, the pro-apoptotic effects of combined niflumic acid-ciglitazone treatment were realized through Cox-2- and PPARγ-independent mechanisms. Taken together, these results suggest that sequential ER stress and caspase-8 activation are critical in combined niflumic acid-ciglitazone treatment-induced apoptosis in human lung cancer cells.

Celecoxib and radioresistant glioblastoma-derived CD133+ cells: improvement in radiotherapeutic effects. Laboratory investigation

OBJECT

Glioblastoma, the most common primary brain tumor, has a poor prognosis, even with aggressive resection and chemoradiotherapy. Recent studies indicate that CD133(+) cells play a key role in radioresistance and recurrence of glioblastoma. Cyclooxygenase-2 (COX-2), which converts arachidonic acid to prostaglandins, is over-expressed in a variety of tumors, including CD133(+) glioblastomas. The COX-2-derived prostaglandins promote neovascularization during tumor development, and conventional radiotherapy increases the proportion of CD133(+) cells rather than eradicating them. The aim of the present study was to investigate the role of celecoxib, a selective COX-2 inhibitor, in enhancing the therapeutic effects of radiation on CD133(+) glioblastomas.

METHODS

Cells positive for CD133 were isolated from glioblastoma specimens and characterized by flow cytometry, then treated with celecoxib and/or ionizing radiation (IR). Clonogenic assay, cell irradiation, cell cycle analysis, Western blot, and xenotransplantation were used to assess the effects of celecoxib alone, IR alone, and IR with celecoxib on CD133(+) and CD133(-) glioblastoma cells. Three separate xenotransplantation experiments were carried out using 310 severe combined immunodeficient (SCID) mice: 1) an initial tumorigenicity evaluation in which 3 different quantities of untreated CD133(-) cells or untreated or pretreated CD133(+) cells (5 treatment conditions) from 7 different tumors were injected into the striatum of 2 mice (210 mice total); 2) a tumor growth study (50 mice); and 3) a survival study (50 mice). For these last 2 studies the same 5 categories of cells were used as in the tumorigenicity (untreated CD133(-) cells, untreated or pretreated CD133(+) cells, with pretreatment consisting of celecoxib alone, IR alone, or IR and celecoxib), but only 1 cell source (Case 2) and quantity (5 × 10(4) cells) were used.

RESULTS

High levels of COX-2 protein were detected in the CD133(+) but not the CD133(-) glioblastoma cells. The authors further demonstrated that 30 μM celecoxib was able to effectively enhance the IR effect in inhibiting colony formation and increasing IR-mediated apoptosis in celecoxib-treated CD133(+) glioblastoma cells. Furthermore, reduction in radioresistance was correlated with the induction of G2/M arrest, which was partially mediated through the increase in the level of phosphorylated-cdc2. In vivo xenotransplant analysis further confirmed that CD133(+)-associated tumorigenicity was significantly suppressed by celecoxib treatment. Importantly, pretreatment of CD133(+) glioblastoma cells with a combination of celecoxib and IR before injection into the striatum of SCID mice resulted in a statistically significant reduction in tumor growth and a statistically significant increase in the mean survival rate of the mice.

CONCLUSIONS

Celecoxib combined with radiation plays a critical role in the suppression of growth of CD133(+) glioblastoma stemlike cells. Celecoxib is therefore a radiosensitizing drug for clinical application in glioblastoma.

Relation of the expression of cyclooxygenase-2 in colorectal adenomas and adenocarcinomas to angiogenesis and prognosis

Purpose

Recent studies have shown that cyclooxygenase (COX)-2 may be involved in tumor growth, invasion and apoptosis in various carcinomas. Vascular endothelial growth factor (VEGF) has a potent angiogenic activity, and COX-2 promotes angiogenesis by modulating angiogenic factors, including VEGF. Endothelial growth factor receptor (EGFR) is considered as a factor of cell growth, maturation and cell death. The current study was designed to investigate the possible roles of COX-2 in colorectal tumor progression and angiogenesis.

Methods

Fifty colorectal adenomas and forty adenocarcinomas were investigated by using immunohistochemical staining for COX-2, VEGF and EGFR. The correlations of COX-2, VEGF and EGFR with the grade of dysplasia, the size of the adenoma, and various clinicopathologic factors were studied.

Results

The expressions of COX-2, VEGF and EGFR were each significantly correlated with carcinomatous transformation, and the expressions of COX-2 and VEGF were significantly correlated. COX-2 and EGFR showed correlations with adenomas rather than adenocarcinomas. However, no correlations of COX-2, VEGF and EGFR expression to other clinicopathologic factors, except tumor size in EGFR expression, were detected.

Conclusion

These results suggest that COX-2 may play an important role in carcinogenesis through interaction with VEGF and EGFR in human colorectal cancer.

Short-term therapy with celecoxib and lansoprazole modulates Th1/ Th2 immune response in human gastric mucosa

BACKGROUND

Selective cyclooxygenase-2 (COX-2) inhibitors and proton pump inhibitors may exert immune-mediated effects in human gastric mucosa. T-cell immune response plays a role in Helicobacter pylori-induced pathogenesis. This study evaluated effects of celecoxib and lansoprazole on T-helper (Th) 1 and Th2 immune response in human gastric mucosa.

METHODS

Dyspeptic patients with or without osteoarticular pain were given one of the following 4-week therapies: celecoxib 200 mg, celecoxib 200 mg plus lansoprazole 30 mg, and lansoprazole 30 mg daily. Expression of COX-2, T-bet, and pSTAT6 and production of prostaglandin E₂ (PGE₂), interferon (IFN)-γ, and interleukin (IL)-4 were determined in gastric biopsies before and after therapy. Histology was evaluated.

RESULTS

Cyclooxygenase-2 expression and PGE₂ production was higher, and Th1 signaling pathway was predominant in H. pylori-infected vs. uninfected patients. T-bet expression and IFN-γ production increased, while STAT6 activation and IL-4 production decreased following therapy with celecoxib and celecoxib plus lansoprazole, respectively. Th1 and Th2 signaling pathways down-regulated after therapy with lansoprazole, and this was associated with an improvement of gastritis. Effect of therapy was not affected by H. pylori status.

CONCLUSION

Celecoxib and lansoprazole modulate Th1/Th2 immune response in human gastric mucosa. The use of these drugs may interfere with long-term course of gastritis.

miR-802 regulates human angiotensin II type 1 receptor expression in intestinal epithelial C2BBe1 cells

Studies have demonstrated that angiotensin II (Ang II) can regulate intestinal fluid and electrolyte transport and control intestinal wall muscular activity. Ang II is also a proinflammatory mediator that participates in inflammatory responses such as apoptosis, angiogenesis, and vascular remodeling; accumulating evidence suggests that this hormone may be involved in gastrointestinal (GI) inflammation and carcinogenesis. Ang II binds to two distinct G protein-coupled receptor subtypes, the AT(1)R and AT(2)R, which are widely expressed in the GI system. Together these studies suggest that Ang II-AT(1)R/-AT(2)R actions may play an important role in GI tract physiology and pathophysiology. Currently it is not known whether miRNAs can regulate the expression of the human AT(1)R (hAT(1)R) in the GI system. PCR and in situ hybridization experiments demonstrated that miR-802 was abundantly expressed in human colon and intestine. Luciferase reporter assays demonstrated that miR-802 could directly interact with the bioinformatics-predicted target site harbored within the 3'-untranslated region of the hAT(1)R mRNA. To validate that the levels of miR-802 were physiologically relevant in the GI system, we demonstrated that miR-802 "loss-of-function" experiments resulted in augmented hAT(1)R levels and enhanced Ang II-induced signaling in a human intestinal epithelial cell line. These results suggest that miR-802 can modulate the expression of the hAT(1)R in the GI tract and ultimately play a role in regulating the biological efficacy of Ang II in this system.

Non-Steroidal Anti-Inflammatory Drugs in the Carcinogenesis of the Gastrointestinal Tract

It is estimated that underlying infections and inflammatory responses are linked to 15–20% of all deaths from cancer worldwide. Inflammation is a physiologic process in response to tissue damage resulting from microbial pathogen infection, chemical irritation, and/or wounding. Tissues injured throughout the recruitment of inflammatory cells such as macrophages and neutrophils, generate a great amount of growth factors, cytokines, and reactive oxygen and nitrogen species that may cause DNA damage that in turn predisposes to the transformation from chronic inflammation to neoplasia. Cyclooxygenase (COX), playing a key role in cell homeostasis, angiogenesis and tumourigenesis, may represent the link between inflammation and cancer. Currently COX is becoming a pharmacological target for cancer prevention and treatment.

Inhibition of arachidonic acid metabolism decreases tumor cell invasion and matrix metalloproteinase expression

Head and neck cancers are known to synthesize arachidonic acid metabolites. Interfering with arachidonic acid metabolism may inhibit growth and invasiveness of cancer cells. In this study we investigate effects of sulindac (the non-selective COX inhibitor), aspirin (the irreversible, preferential COX-1 inhibitor), NS-398 (the selective COX-2 inhibitor), NDGA (nordihydroguaiaretic acid, the selective LOX inhibitor) and ETYA (5,8,11,14-eicosatetraynoic acid, the COX and LOX inhibitor) on cell viability, MMP-2 and MMP-9 activities, and in vitro invasion of cancer cells derived from primary and metastatic head and neck, and colon cancers. The inhibitors of COX and/or LOX could inhibit cell proliferation, MMP activity and invasion in head and neck and colon cancer cells. However, the inhibitory effect was obviously observed in colon cancer cells. Inhibition of arachidonic acid metabolism caused a decrease in cancer cell motility, which partially explained by the inhibition of MMPs. Therefore, COX and LOX pathways play important roles in head and neck cancer cell growth.

NSAIDs and Cell Proliferation in Colorectal Cancer

Colon cancer is common worldwide and accounts for significant morbidity and mortality in patients. Fortunately, epidemiological studies have demonstrated that continuous therapy with NSAIDs offers real promise of chemoprevention and adjunct therapy for colon cancer patients. Tumour growth is the result of complex regulation that determines the balance between cell proliferation and cell death. How NSAIDs affect this balance is important for understanding and improving treatment strategies and drug effectiveness. NSAIDs inhibit proliferation and impair the growth of colon cancer cell lines when tested in culture in vitro and many NSAIDs also prevent tumorigenesis and reduce tumour growth in animal models and in patients, but the relationship to inhibition of tumour cell proliferation is less convincing, principally due to gaps in the available data. High concentrations of NSAIDs are required in vitro to achieve cancer cell inhibition and growth retardation at varying time-points following treatment. However, the results from studies with colon cancer cell xenografts are promising and, together with better comparative data on anti-proliferative NSAID concentrations and doses (for in vitro and in vivo administration), could provide more information to improve our understanding of the relationships between these agents, dose and dosing regimen, and cellular environment.

NSAID sulindac and its analog bind RXRalpha and inhibit RXRalpha-dependent AKT signaling

Nonsteroidal anti-inflammatory drugs (NSAIDs) exert their anticancer effects through cyclooxygenase-2 (COX-2)-dependent and independent mechanisms. Here, we report that Sulindac, an NSAID, induces apoptosis by binding to retinoid X receptor-alpha (RXRalpha). We identified an N-terminally truncated RXRalpha (tRXRalpha) in several cancer cell lines and primary tumors, which interacted with the p85alpha subunit of phosphatidylinositol-3-OH kinase (PI3K). Tumor necrosis factor-alpha (TNFalpha) promoted tRXRalpha interaction with the p85alpha, activating PI3K/AKT signaling. When combined with TNFalpha, Sulindac inhibited TNFalpha-induced tRXRalpha/p85alpha interaction, leading to activation of the death receptor-mediated apoptotic pathway. We designed and synthesized a Sulindac analog K-80003, which has increased affinity to RXRalpha but lacks COX inhibitory activity. K-80003 displayed enhanced efficacy in inhibiting tRXRalpha-dependent AKT activation and tRXRalpha tumor growth in animals.

Selective visualization of cyclooxygenase-2 in inflammation and cancer by targeted fluorescent imaging agents

Effective diagnosis of inflammation and cancer by molecular imaging is challenging because of interference from nonselective accumulation of the contrast agents in normal tissues. Here, we report a series of novel fluorescence imaging agents that efficiently target cyclooxygenase-2 (COX-2), which is normally absent from cells, but is found at high levels in inflammatory lesions and in many premalignant and malignant tumors. After either i.p. or i.v. injection, these reagents become highly enriched in inflamed or tumor tissue compared with normal tissue and this accumulation provides sufficient signal for in vivo fluorescence imaging. Further, we show that only the intact parent compound is found in the region of interest. COX-2-specific delivery was unambiguously confirmed using animals bearing targeted deletions of COX-2 and by blocking the COX-2 active site with high-affinity inhibitors in both in vitro and in vivo models. Because of their high specificity, contrast, and detectability, these fluorocoxibs are ideal candidates for detection of inflammatory lesions or early-stage COX-2-expressing human cancers, such as those in the esophagus, oropharynx, and colon.

17beta-estradiol inhibits prostaglandin E2-induced COX-2 expressions and cell migration by suppressing Akt and ERK1/2 signaling pathways in human LoVo colon cancer cells

Epidemiological studies demonstrate that the incidence and mortality rates of colorectal cancer in women are lower than in men. However, it is unknown if 17beta-estradiol treatment is sufficient to inhibit prostaglandin E2 (PGE2)-induced cellular motility in human colon cancer cells. Upregulation of cyclooxygenase-2 (COX-2) is reported to associate with the development of cancer cell mobility, metastasis, and subsequent malignant tumor. After administration of inhibitors including LY294002 (Akt activation inhibitor), U0126 (ERK1/2 inhibitor), SB203580 (p38 MAPK inhibitor), SP600125 (JNK1/2 inhibitor), or QNZ (NFkappaB inhibitor), we found that PGE2 treatment increases COX-2 via Akt and ERK1/2 pathways, thus promoting cellular motility in human LoVo cancer cells. We further observed that 17beta-estradiol treatment inhibits PGE2-induced COX-2 expression and cellular motility via suppressing activation of Akt and ERK1/2 in human LoVo cancer cells. Collectively, these results suggest that 17beta-estradiol treatment dramatically inhibits PGE2-induced progression of human LoVo colon cancer cells.

The role of cyclooxygenase-2 in cell proliferation and cell death in human malignancies

It is well admitted that the link between chronic inflammation and cancer involves cytokines and mediators of inflammatory pathways, which act during the different steps of tumorigenesis. The cyclooxygenases (COXs) are a family of enzymes, which catalyze the rate-limiting step of prostaglandin biosynthesis. This family contains three members: ubiquitously expressed COX-1, which is involved in homeostasis; the inducible COX-2 isoform, which is upregulated during both inflammation and cancer; and COX-3, expressed in brain and spinal cord, whose functions remain to be elucidated. COX-2 was described to modulate cell proliferation and apoptosis mainly in solid tumors, that is, colorectal, breast, and prostate cancers, and, more recently, in hematological malignancies. These findings prompt us to analyze here the effects of a combination of COX-2 inhibitors together with different clinically used therapeutic strategies in order to further improve the efficiency of future anticancer treatments. COX-2 modulation is a promising field investigated by many research groups.

Nonsteroidal anti-inflammatory drugs: effects on mortality after colorectal cancer diagnosis

BACKGROUND

Nonsteroidal anti-inflammatory drug (NSAID) use has been associated with a decreased colorectal cancer (CRC) risk. However, to the best of the authors' knowledge, the effects of NSAID on clinical outcomes after CRC diagnosis are not well defined. The authors investigated the association between prediagnosis NSAID use and mortality after CRC diagnosis among women in the California Teachers Study cohort.

METHODS

Women aged <85 years participating in the California Teachers Study, without a prior CRC diagnosis at baseline (1995-1996), and who were diagnosed with CRC during follow-up through December 2005, were eligible for analysis of the association between prediagnosis NSAID use and mortality. NSAID use (including aspirin and ibuprofen) was collected through a self-administered questionnaire. Cancer occurrence was identified through California Cancer Registry linkage. Multivariate Cox proportional hazards regression models were used to estimate hazards ratios (HR) for death and 95% confidence intervals (95% CIs).

RESULTS

Among 621 CRC patients who were identified, 64% reported no prediagnosis regular NSAID use, 17% reported use of 1 to 6 days/week, and 20% reported daily use. A duration of NSAID use <5 years was reported by 17% of patients and a use of >or=5 years was reported by 18%. Regular prediagnosis NSAID use (1-3 days/week, 4-6 days/week, and daily) versus none was associated with improved overall survival (OS) (HR, 0.71; 95% CI, 0.53-0.95) and CRC-specific survival (HR, 0.58; 95% CI 0.40-0.84) after adjustment for clinically relevant factors. Prediagnosis NSAID use >or=5 years (vs none) was found to be associated with improved OS (HR, 0.55; 95% CI, 0.37-0.84) and CRC-specific survival (HR, 0.40; 95% CI, 0.23-0.71) in adjusted analyses.

CONCLUSIONS

When used regularly or over a prolonged duration before CRC diagnosis, NSAIDs are associated with decreased mortality among female CRC patients.

Hypertonic environment elicits cyclooxygenase-2-driven prostaglandin E2 generation by colon cancer cells: role of cytosolic phospholipase A2-alpha and kinase signaling pathways

Cyclooxygenase (COX)-2-derived prostaglandin (PG)E(2) controls many aspects of colon cancer development, modulating from apoptosis resistance and cell proliferation to angiogenesis, invasion, and metastasis. Here, we investigated the role of different phospholipases (PL)A(2) in supplying arachidonic acid (AA) for COX-2-dependent PGE(2) generation and signaling pathways involved in activation of colon cancer cells by a physiologically relevant stimulus. To emulate the hypertonic environment found physiologically in colon, the human colon cancer cell line Caco-2 was maintained in hypertonic complete DMEM medium. Human colon cancer cell line Caco-2 exposed to a hypertonic environment responded with marked AA release, COX-2 induction and PGE(2) generation. Selective secretory (s)PLA(2) and calcium-independent (i)PLA(2) inhibitors did not modify PGE(2) generation, while either COX-2 or cytosolic (c)PLA(2) inhibitors completely inhibited PGE(2) generation. cPLA(2)-alpha was responsible for AA supply for PGE(2) generation, but had no role in COX-2 induction. Mitogen-activated protein (MAP) kinases, ERK 1/2, p38, and JNK, participated in the signaling events that lead to PGE(2) generation by modulating AA release, but only ERK 1/2 was involved in COX-2 upregulation. Our results indicate that hypertonic stress activates PGE(2) generation by Caco-2 cells through a mechanism dependent on MAP kinase-regulated AA mobilization, increased cPLA(2)-alpha activity, and COX-2 induction.

Elevated levels of urinary prostaglandin e metabolite indicate a poor prognosis in ever smoker head and neck squamous cell carcinoma patients

Cyclooxygenase (COX)-derived prostaglandin E(2) (PGE(2)) plays a role in the development and progression of several tumor types including head and neck squamous cell carcinoma (HNSCC). Measurements of urinary PGE metabolite (PGE-M) can be used as an index of systemic PGE(2) production. In ever smokers, increased levels of urinary PGE-M reflect increased COX-2 activity. In this study, we determined whether baseline levels of urinary PGE-M were prognostic for ever smoker HNSCC patients. A retrospective chart review of ever smoker HNSCC patients treated with curative intent was done. Fifteen of 31 evaluable patients developed progressive disease (recurrence or a second primary tumor) after a median follow-up of 38 months. There were no statistically significant differences between patients with (n = 15) or without disease progression (n = 16) with regard to stage, site, treatment received, smoking status, and aspirin use during follow-up. Median urinary PGE-M levels were significantly higher in HNSCC patients with disease progression (21.7 ng/mg creatinine) compared with patients without (13.35 ng/mg creatinine; P = 0.03). Importantly, patients with high baseline levels of urinary PGE-M had a significantly greater risk of disease progression (hazard ratio, 4.76, 95% CI, 1.31-17.30; P < 0.01) and death (hazard ratio, 9.54; 95% CI, 1.17-77.7; P = 0.01) than patients with low baseline levels of urinary PGE-M. These differences were most evident among patients with early-stage disease. Taken together, our findings suggest that high baseline levels of urinary PGE-M indicate a poor prognosis in HNSCC patients. Possibly, HNSCC patients with high COX-2 activity manifested by elevated urinary PGE-M will benefit from treatment with a COX-2 inhibitor.

Combination of sulindac and antimicrobial eradication of Helicobacter pylori prevents progression of gastric cancer in hypergastrinemic INS-GAS mice

Helicobacter pylori infection causes severe dysplasia manifested as gastrointestinal intraepithelial neoplasia (GIN) after 28 weeks post-H. pylori infection (WPI) in cancer-prone, hypergastrinemic male INS-GAS mice. We examined the efficacy of the nonsteroidal anti-inflammatory drug sulindac (400 ppm in drinking water) alone, the CCK2/gastrin receptor antagonist YM022 (45 mg/kg/wk) alone, and sulindac or YM022 combined with H. pylori eradication therapy to prevent H. pylori-associated gastric cancer in male INS-GAS mice. Treatments started at 22 WPI, and mice were euthanized at 28 WPI. In uninfected mice, all treatments significantly delayed development of spontaneous GIN (P < 0.05). In H. pylori-infected mice, sulindac alone or YM022 alone had no protective effect on H. pylori-associated GIN. Importantly, sulindac exacerbated the severity of H. pylori-associated gastritis despite decreased gastric prostaglandin E(2) levels. However, sulindac combined with H. pylori antimicrobial eradication reduced the incidence of GIN (P < 0.05), whereas YM022 combined with antimicrobial eradication did not reduce GIN. In infected mice, sulindac or YM022 treatment did not alter gastric expression of the proinflammatory cytokines Ifn-gamma and Tnf-alpha and mucosal cell proliferation. Sulindac or YM022 combined with antimicrobial eradication down-regulated mRNA levels of Ifn-gamma and Tnf-alpha and mucosal cell proliferation (P < 0.05). We conclude that sulindac enhances H. pylori gastritis and may promote inflammation-mediated gastric carcinogenesis. The combination of sulindac and antimicrobial H. pylori eradication was beneficial for reducing proinflammatory cytokine mRNA in the stomach and preventing progression from severe dysplasia to gastric cancer in H. pylori-infected INS-GAS mice.

Beta-catenin is involved in alterations in mitochondrial activity in non-transformed intestinal epithelial and colon cancer cells

BACKGROUND

Alteration in respiratory activity and mitochondrial DNA (mtDNA) transcription seems to be an important feature of cancer cells. Leukotriene D(4) (LTD(4)) is a proinflammatory mediator implicated in the pathology of chronic inflammation and cancer. We have shown earlier that LTD(4) causes translocation of beta-catenin both to the mitochondria, in which it associates with the survival protein Bcl-2 identifying a novel role for beta-catenin in cell survival, and to the nucleus in which it activates the TCF/LEF transcription machinery.

METHODS

Here we have used non-transformed intestinal epithelial Int 407 cells and Caco-2 colon cancer cells, transfected or not with wild type and mutated (S33Y) beta-catenin to analyse its effect on mitochondria activity. We have measured the ATP/ADP ratio, and transcription of the mtDNA genes ND2, ND6 and 16 s in these cells stimulated or not with LTD(4).

RESULTS

We have shown for the first time that LTD(4) triggers a cellular increase in NADPH dehydrogenase activity and ATP/ADP ratio. In addition, LTD(4) significantly increased the transcription of mtDNA genes. Overexpression of wild-type beta-catenin or a constitutively active beta-catenin mutant mimicked the effect of LTD(4) on ATP/ADP ratio and mtDNA transcription. These elevations in mitochondrial activity resulted in increased reactive oxygen species levels and subsequent activations of the p65 subunit of NF-kappaB.

CONCLUSIONS

The present novel data show that LTD(4), presumably through beta-catenin accumulation in the mitochondria, affects mitochondrial activity, lending further credence to the idea that inflammatory signalling pathways are intrinsically linked with potential oncogenic signals.

Influence of paeonol on expression of COX-2 and p27 in HT-29 cells

AIM: To investigate the effect of paeonol on controlling the proliferation of colorectal cancer cell line HT-29 and to discuss its possible mechanism.

METHODS: The inhibitory effect of paeonol on proliferation of HT-29 cells was detected by MTT assay. The results of apoptosis were measured by flow cytometry. Immunocytochemical staining was performed to detect the expression of cyclooxygenase-2 (COX-2) and protein p27 in HT-29 cells treated with paeonol at different concentrations. Reverse transcription-polymerase chain reaction (RT-PCR) was used for mRNA analysis.

RESULTS: From the data of both MTT and flow cytometry, we observed that cell proliferation was inhibited by different concentrations of paeonol. By immunocytochemical staining, we found that HT-29 cells treated with paeonol (0.024-1.504 mmol/L) reflected reduced expression of COX-2 and increased expression of p27 in a dose-dependent manner. RT-PCR showed that paeonol down-regulated COX-2 and up-regulated p27 in a dose- and time-dependent manner in HT-29 cells.

CONCLUSION: One of the apoptotic mechanisms of paeonol is down-regulation of COX-2. p27 is up-regulated simultaneously and plays an important part in controlling cell proliferation and is a crucial factor in the Fas/FasL apoptosis pathway.

Curcumin sensitizes human colorectal cancer to capecitabine by modulation of cyclin D1, COX-2, MMP-9, VEGF and CXCR4 expression in an orthotopic mouse model

Because of the poor prognosis and the development of resistance against chemotherapeutic drugs, the current treatment for advanced metastatic colorectal cancer (CRC) is ineffective. Whether curcumin (a component of turmeric) can potentiate the effect of capecitabine against growth and metastasis of CRC was investigated. The effect of curcumin on proliferation of CRC cell lines was examined by mitochondrial dye-uptake assay, apoptosis by esterase staining, nuclear factor-kappaB (NF-kappaB) by electrophoretic mobility shift assay and gene expression by Western blot analysis. The effect of curcumin on the growth and metastasis of CRC was also examined in orthotopically implanted tumors in nude mice. In vitro, curcumin inhibited the proliferation of human CRC cell lines, potentiated capecitabine-induced apoptosis, inhibited NF-kappaB activation and suppressed NF-kappaB-regulated gene products. In nude mice, the combination of curcumin and capecitabine was found to be more effective than either agent alone in reducing tumor volume (p = 0.001 vs. control; p = 0.031 vs. capecitabine alone), Ki-67 proliferation index (p = 0.001 vs. control) and microvessel density marker CD31. The combination treatment was also highly effective in suppressing ascites and distant metastasis to the liver, intestines, lungs, rectum and spleen. This effect was accompanied by suppressed expression of activated NF-kappaB and NF-kappaB-regulated gene products (cyclin D1,c-myc, bcl-2, bcl-xL, cIAP-1, COX-2, ICAM-1, MMP-9, CXCR4 and VEGF). Overall, our results suggest that curcumin sensitizes CRC to the antitumor and antimetastatic effects of capecitabine by suppressing NF-kappaB cell signaling pathway.

Nucleoside diphosphate kinase/Nm23 and Epstein-Barr virus

Nm23-H1 was discovered as the first metastasis suppressor gene about 20 years ago. Since then, extensive work has contributed to understanding its role in various cellular signaling pathways. Its association with a range of human cancers as well as its ability to regulate cell cycle and suppress metastasis has been explored. We have determined that the EBV-encoded nuclear antigens, EBNA3C and EBNA1, required for EBV-mediated lymphoproliferation and for maintenance EBV genome extrachromosomally in dividing mammalian cells, respectively, target and disrupt the physiological role of Nm23-H1 in the context of cell proliferation and cell migration. This review will focus on the interaction of Nm23-H1 with the Epstein-Barr virus nuclear antigens, EBNA3C and EBNA1 and the functional significance of this interaction as it relates to EBV pathogenesis.

Aspirin use and survival after diagnosis of colorectal cancer

CONTEXT

Aspirin reduces risk of colorectal neoplasia in randomized trials and inhibits tumor growth and metastases in animal models. However, the influence of aspirin on survival after diagnosis of colorectal cancer is unknown.

OBJECTIVE

To examine the association between aspirin use after colorectal cancer diagnosis on colorectal cancer-specific and overall survival.

DESIGN, SETTING, AND PARTICIPANTS

Prospective cohort study of 1279 men and women diagnosed with stage I, II, or III colorectal cancer. Participants were enrolled in 2 nationwide health professional cohorts in 1980 and 1986 prior to diagnosis and followed up through June 1, 2008.

MAIN OUTCOME MEASURE

Colorectal cancer-specific and overall mortality.

RESULTS

After a median follow-up of 11.8 years, there were 193 total deaths (35%) and 81 colorectal cancer-specific deaths (15%) among 549 participants who regularly used aspirin after colorectal cancer diagnosis, compared with 287 total deaths (39%) and 141 colorectal cancer-specific deaths (19%) among 730 participants who did not use aspirin. Compared with nonusers, participants who regularly used aspirin after diagnosis experienced a multivariate hazard ratio (HR) for colorectal cancer-specific mortality of 0.71 (95% confidence interval [CI], 0.53-0.95) and for overall mortality of 0.79 (95% CI, 0.65-0.97). Among 719 participants who did not use aspirin before diagnosis, aspirin use initiated after diagnosis was associated with a multivariate HR for colorectal cancer-specific mortality of 0.53 (95% CI, 0.33-0.86). Among 459 participants with colorectal cancers that were accessible for immunohistochemical assessment, the effect of aspirin differed significantly according to cyclooxygenase 2 (COX-2) expression (P for interaction = .04). Regular aspirin use after diagnosis was associated with a lower risk of colorectal cancer-specific mortality among participants in whom primary tumors overexpressed COX-2 (multivariate HR, 0.39; 95% CI, 0.20-0.76), whereas aspirin use was not associated with lower risk among those with primary tumors with weak or absent expression (multivariate HR, 1.22; 95% CI, 0.36-4.18).

CONCLUSION

Regular aspirin use after the diagnosis of colorectal cancer is associated with lower risk of colorectal cancer-specific and overall mortality, especially among individuals with tumors that overexpress COX-2.

Regulation of the apoptosis-inducing kinase DRAK2 by cyclooxygenase-2 in colorectal cancer

Background:

Cyclooxygenase-2 (COX-2) is over-expressed in colorectal cancer (CRC), rendering tumour cells resistant to apoptosis. Selective COX-2 inhibition is effective in CRC prevention, although having adverse cardiovascular effects, thus focus has shifted to downstream pathways.

Methods:

Microarray experiments identified genes regulated by COX-2 in HCA7 CRC cells. In vitro and in vivo regulation of DRAK2 (DAP kinase-related apoptosis-inducing kinase 2 or STK17β, an apoptosis-inducing kinase) by COX-2 was validated by qRT-PCR.

Results:

Inhibition of COX-2 induced apoptosis and enhanced DRAK2 expression in HCA7 cells (4.4-fold increase at 4 h by qRT-PCR, P=0.001), an effect prevented by co-administration of PGE₂. DRAK2 levels were suppressed in a panel of human colorectal tumours (n=10) compared to normal mucosa, and showed inverse correlation with COX-2 expression (R=−0.68, R²=0.46, P=0.03). Administration of the selective COX-2 inhibitor rofecoxib to patients with CRC (n=5) induced DRAK2 expression in tumours (2.5-fold increase, P=0.01). In vitro silencing of DRAK2 by RNAi enhanced CRC cell survival following COX-2 inhibitor treatment.

Conclusion:

DRAK2 is a serine–threonine kinase implicated in the regulation of apoptosis and is negatively regulated by COX-2 in vitro and in vivo, suggesting a novel mechanism for the effect of COX-2 on cancer cell survival.

Catalytic, asymmetric alpha-fluorination of acid chlorides: dual metal-ketene enolate activation

In this Communication, we disclose a catalytic, highly enantioselective (up to >99% ee) alpha-fluorination of acid chlorides to produce a variety of optically active carboxylic acid derivatives from readily accessible and commercially available starting materials. The reaction depends on dually activated ketene enolates generated from two discrete catalysts--a chiral nucleophile and an achiral transition metal complex working in tandem. The active, putative alpha-fluorobis(sulfonimide) intermediates readily transacylate in situ under mild conditions upon addition of a wide variety of nucleophiles, including complex natural products. As a consequence, the power of this method is witnessed by the broad range of alpha-fluorinated products that can be accessed efficiently depending on the work up conditions.

Cyclo-oxygenase 2 inhibitor, nabumetone, inhibits proliferation in chronic myeloid leukemia cell lines

The anti-tumor effect of cyclo-oxygenase (COX) inhibitors has been documented in several studies. COX2 inhibitors have attracted more attention because of the fewer side-effects and the more prominent anti-tumor effects. However, experience with these drugs in hematological malignancies is limited. In our study, a potent COX2 inhibitor, nabumetone (NBT), was investigated for its anti-proliferative and apoptotic effects in K-562 and Meg-01 chronic myeloid leukemia blastic cell lines as a single agent or in combination with adriamycin (ADR) and interferon alpha (IFN-a). In these cell lines, a dose-dependent inhibition of proliferation was observed with NBT. We observed no significant apoptotic effect of NBT. However, NBT potentiated the apoptotic effect of ADR in the K-562 cell line. Bcl-2 expression was reduced by NBT (11% vs. 2%). The combination of NBT with IFN did not have any significant effect on the K-562 cell line. We suggest that NBT inhibits proliferation and potentiates the apoptotic effect of ADR in chronic myeloid leukemia cell lines.

Proneoplastic effects of PGE2 mediated by EP4 receptor in colorectal cancer

Background

Prostaglandin E₂ (PGE₂) is the major product of Cyclooxygenase-2 (COX-2) in colorectal cancer (CRC). We aimed to assess PGE₂ cell surface receptors (EP 1–4) to examine the mechanisms by which PGE₂ regulates tumour progression.

Methods

Gene expression studies were performed by quantitative RT-PCR. Cell cycle was analysed by flow cytometry with cell proliferation quantified by BrdU incorporation measured by enzyme immunoassay. Immunohistochemistry was employed for expression studies on formalin fixed paraffin embedded tumour tissue.

Results

EP4 was the most abundant subtype of PGE₂ receptor in HT-29 and HCA7 cells (which show COX-2 dependent PGE₂ generation) and was consistently the most abundant transcript in human colorectal tumours (n = 8) by qRT-PCR (ANOVA, p = 0.01). G0/G1 cell cycle arrest was observed in HT-29 cells treated with SC-236 5 μM (selective COX-2 inhibitor) for 24 hours (p = 0.02), an effect abrogated by co-incubation with PGE₂ (1 μM). G0/G1 arrest was also seen with a specific EP4 receptor antagonist (EP4A, L-161982) (p = 0.01). Treatment of HT-29 cells with either SC-236 or EP4A caused reduction in intracellular cAMP (ANOVA, p = 0.01). Early induction in p21^WAF1/CIP1 expression (by qRT-PCR) was seen with EP4A treatment (mean fold increase 4.4, p = 0.04) while other genes remained unchanged. Similar induction in p21^WAF1/CIP1 was also seen with PD153025 (1 μM), an EGFR tyrosine kinase inhibitor, suggesting EGFR transactivation by EP4 as a potential mechanism. Additive inhibition of HCA7 proliferation was observed with the combination of SC-236 and neutralising antibody to amphiregulin (AR), a soluble EGFR ligand. Concordance in COX-2 and AR localisation in human colorectal tumours was noted.

Conclusion

COX-2 regulates cell cycle transition via EP4 receptor and altered p21^WAF1/CIP1 expression. EGFR pathways appear important. Specific targeting of the EP4 receptor or downstream targets may offer a safer alternative to COX-2 inhibition in the chemoprevention of CRC.

Effects of dietary flaxseed on intestinal tumorigenesis in Apc(Min) mouse

Dietary flaxseed has been shown to prevent azoxymethane (AOM)-induced colorectal cancers in male Fisher rats. The present study was designed to investigate the chemopreventive effects of dietary flaxseed on the development of intestinal tumors in Apc(Min) mice. Apc(Min) mice were divided into five different groups, fed with control (AIN-93M meal), corn meal, flaxseed meal, corn oil, and flaxseed oil supplemented diets. Results showed that dietary flaxseed significantly decreased (P < 0.05) tumor multiplicity and size in the small intestine and colon as compared to control, corn-treated groups. Intestine, colon, and serum samples of corn-treated groups showed higher levels of omega -6 fatty acids, whereas the flaxseed treated groups exhibited higher levels of omega -3 fatty acids. Lignans were detected in the serum, intestine, and colon samples for flaxseed meal group. COX-1 and COX-2 expression in the colon samples from the flaxseed meal group were significantly lower (P < 0.05) as compared to the corn meal group. Dietary flaxseed may be chemopreventive for intestinal tumor development in Apc(Min) mice possibly by increasing omega -3 fatty acid levels, lignans, and decreasing COX-1 and COX-2 levels.

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

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

Effects of non-cytotoxic drugs on the growth of multidrug-resistance human gastric carcinoma cell line

OBJECTIVE

To investigate the effects of the non-cytotoxic drug (cyclooxygenase-2 (COX-2) inhibitor and octreotide) on growth of the multidrug-resistant human gastric carcinoma cell line SGC-7901/ADR.

METHODS

The effects of non-cytotoxic drug on the growth of SGC-7901 and SGC-7901/ADR cells were evaluated by (3)H-thymidine incorporation assay. The apoptosis of cells was measured by the TdT-mediated dUTP nick end-labeling assay (TUNEL) and flow cytometric assay. Western blotting was used to analysis the expression of cyclooxygenase (COX-2) protein in SGC-7901 cells and SGC-7901/ADR cells and P-glycoprotein (P-gp) from SGC-7901/ADR cells with variable treatments. Activator protein-1 binding activity was examined by electrophoretic mobility shift assay.

RESULTS

(3)H-thymidine incorporation into SGC-7901/ADR cells treated with celecoxib was significantly lower than that of control group (471.3 +/- 79.7 cpm vs 917.5 +/- 130.8 cpm, P < 0.05). When combined with octreotide, celecoxib presented lower (3)H-thymidine incorporations than its used alone and decreased to 53.3% of that amount original. Either celecoxib or the combination group markedly induced apoptosis in SGC-7901/ADR cells. COX-2 protein in the SGC-7901/ADR cells was higher than in that of the SGC-7901 cells (1.543 +/- 0.052 vs 0.564 +/- 0.021, P < 0.05). The inhibition of P-gp could be achieved with celecoxib alone and combination with octreotide (0.486 +/- 0.012, 0.252 +/- 0.014 vs 0.941 +/- 0.033, P < 0.05). Moreover, AP-1 binding activity could be suppressed by non-cytotoxic drug and showed a synergistic effect.

CONCLUSION

The combination of non-cytotoxic drug significantly improved the inhibitive effects on the growth of multidrug-resistant human gastric cancer cells.

Cyclooxygenase as a target for chemoprevention in colorectal cancer: lost cause or a concept coming of age?

COX-2 is upregulated at an early stage in colorectal carcinogenesis and generates prostaglandins, which promote cancer cell proliferation, impair apoptosis and enhance angiogenesis, promoting tumour growth and metastasis. There are ample data from animal models and human studies to demonstrate enhanced tumour progression associated with COX-2 activity in cancer cells. Conversely, NSAIDs including aspirin inhibit COX-2 and, therefore, have anti-neoplastic properties. There has been sustained interest in COX-2 as a chemopreventive target in colorectal cancer (CRC) and although both aspirin and COX-2 selective NSAIDs have demonstrated efficacy, adverse effects have limited their widespread adoption. In particular, evidence of the cardiovascular effects of COX-2 selective inhibitors has led to questioning of the suitability of COX-2 as a target for chemoprevention. This review examines the basis for targeting COX-2 in CRC chemoprevention, evaluates the efficacy and safety of the approach and examines future strategies in this area.

Neoplasms escape selective COX-2 inhibition in an animal model of breast cancer

BACKGROUND

Cyclo-oxygenase-2 (COX-2) is up-regulated in malignant tumours rendering it an attractive target for cancer therapeutics. However, whether long-term antagonism maintains its initial efficacy on established tumours is unclear.

METHODS

4T1 cells were injected into the mammary fat pad of BALB/c mice (n = 8). Once tumour deposits were established, animals were randomized into two equal groups to receive either a selective COX-2 inhibitor (SC-236) or a drug vehicle. Further animals similarly treated (n = 7) were studied in diuresis cages allowing urine capture and analysis by mass spectrometry to determine Prostaglandin F-1 levels (PGF-1). In addition, both wild-type receiving SC-236 and COX-2 knockout mice receiving either SC 236 or vehicle were subjected to the same studies to determine whether tumour-derived or host-derived (stromal) COX-2 was the critical element. Finally, BALB/c mice with 4T1 tumours (n = 7) were treated with a combination of COX-2 and lipoxygenase (LOX) inhibition to attenuate this escape phenomenon.

RESULTS

While selective COX-2 inhibition initially retarded tumour growth, a rapid increase in tumour growth rate occurred later (day 9). This escape phenomenon correlated with an increase in urinary PGF-1 levels. An identical trend was also observed whether COX-2 knockout mice received SC-236 or not, suggesting that this effect is due to increased tumour-derived COX-2 production rather than recovery of host COX-2 functional capacity. Finally, dual inhibition of COX and LOX pathways attenuated this escape process.

CONCLUSION

The anti-neoplastic effects of selective COX-2 inhibition may not be sustained as tumours demonstrate an escape capacity. However, this phenomenon maybe attenuated by a combination of COX/LOX inhibitors.

Inhibition of 11beta-hydroxysteroid dehydrogenase type II selectively blocks the tumor COX-2 pathway and suppresses colon carcinogenesis in mice and humans

Colorectal cancer (CRC) is a leading cause of cancer death, yet primary prevention remains the best approach to reducing overall morbidity and mortality. Studies have shown that COX-2-derived PGE2 promotes CRC progression, and both nonselective COX inhibitors (NSAIDs) and selective COX-2 inhibitors (such as glucocorticoids) reduce the number and size of colonic adenomas. However, increased gastrointestinal side effects of NSAIDs and increased cardiovascular risks of selective COX-2 inhibitors limit their use in chemoprevention of CRC. We found that expression of 11beta-hydroxysteroid dehydrogenase type II (11betaHSD2), which converts active glucocorticoids to inactive keto-forms, increased in human colonic and Apc+/min mouse intestinal adenomas and correlated with increased COX-2 expression and activity. Furthermore, pharmacologic inhibition or gene silencing of 11betaHSD2 inhibited COX-2-mediated PGE2 production in tumors and prevented adenoma formation, tumor growth, and metastasis in mice. Inhibition of 11betaHSD2 did not reduce systemic prostacyclin production or accelerate atherosclerosis in mice, thereby avoiding the major cardiovascular side effects seen with systemic COX-2 inhibitors. Therefore, 11betaHSD2 inhibition represents what we believe to be a novel approach for CRC chemoprevention and therapy by increasing tumor glucocorticoid activity, which in turn selectively blocks local COX-2 activity.

PLA2 (group IIA phospholipase A2) as a prognostic determinant in stage II colorectal carcinoma

BACKGROUND

Approximately 30% of all colorectal cancer (CRC) patients are diagnosed with stage II disease. Adjuvant therapy is not widely recommended. However, it is well established that a subgroup of patients with stage II are at high risk for recurrence within their lifetime and should be considered for adjuvant chemotherapy. The present work was designed to assess the value of group IIA phospholipase A2 (PLA2) as a predictor of disease outcome in stage II CRC patients with long-term follow-up.

PATIENTS AND METHODS

The present study comprises a series of 116 patients who underwent bowel resection for stage II CRC during 1981-1990 at Turku University Hospital. Archival paraffin-embedded CRC tissue samples were used to prepare tissue microarray blocks for immunohistochemical staining with PLA2.

RESULTS

Fifty-five percent of all tumors were positive for PLA2. There was no significant correlation between PLA2 expression and age, sex, depth of invasion and lymph node status. In Kaplan-Meier survival analysis, there was a significant (P = 0.010) difference in disease-free survival (DFS) between patients with negative tumors (longer DFS) and those with positive tumors. The same was true with disease-specific survival (DSS), patients with PLA2-negative tumors living significantly longer (P = 0.025). In multivariate (Cox) survival analysis, however, PLA2 was not an independent predictor of DFS or DSS. In subgroup analysis, the right-sided tumors with negative PLA2 staining had remarkably better prognosis (P = 0.010) than PLA2-positive left-sided tumors.

CONCLUSIONS

Quantification of PLA2 expression seems to provide valuable prognostic information in stage II CRC, particularly in selecting the patients at high risk for recurrent disease who might benefit from adjuvant therapy.

A phase II study of celecoxib in combination with paclitaxel, carboplatin, and radiotherapy for patients with inoperable stage IIIA/B non-small cell lung cancer

PURPOSE

Cyclooxygenase (COX)-2 up-regulation plays an important role in the pathogenesis of lung cancer. Selective COX-2 inhibitors have promoted chemosensitivity and radiosensitivity of tumor cells in preclinical trials.

EXPERIMENTAL DESIGN

In a single-institution phase II study, we sought to determine the effectiveness of concurrent chemoradiation given with celecoxib and examined biomarkers to predict response to COX-2 inhibition.

RESULTS

Seventeen patients with stage IIIA or IIIB non-small cell lung cancer (NSCLC) were enrolled in the study. All received 400 mg celecoxib twice daily continuously while on trial in addition to concurrent chemoradiation therapy with paclitaxel and carboplatin. Celecoxib was continued until disease progression. The overall objective response rate was 42.9%, and the median overall survival time was 203 days. In contrast to nonresponders, those patients with complete and partial responses had a significant decrease in the level of urinary 11alpha-hydroxy-9,15-dioxo-2,3,4,5-tetranor-prostane-1,20-dioic acid (PGE-M), the major metabolite of prostaglandin E(2), after 1 week of celecoxib administration. Patients with very high levels of PGE-M before initiation of therapy also responded poorly to therapy. Serum vascular endothelial growth factor levels did not predict response or survival.

CONCLUSION

The trial was terminated because it did not meet the predetermined goal of 80% overall response rate. In unselected patients, the addition of celecoxib to concurrent chemoradiotherapy with inoperable stage IIIA/B NSCLC does not improve survival. Urinary PGE-M is a promising biomarker for predicting response to COX-2 inhibition in NSCLC.

ESE-1/EGR-1 pathway plays a role in tolfenamic acid-induced apoptosis in colorectal cancer cells

Nonsteroidal anti-inflammatory drugs (NSAIDs) are known to prevent colorectal tumorigenesis. Although antitumor effects of NSAIDs are mainly due to inhibition of cyclooxygenase activity, there is increasing evidence that cyclooxygenase-independent mechanisms may also play an important role. The early growth response-1 (EGR-1) gene is a member of the immediate-early gene family and has been identified as a tumor suppressor gene. Tolfenamic acid is a NSAID that exhibits anticancer activity in a pancreatic cancer model. In the present study, we investigated the anticancer activity of tolfenamic acid in human colorectal cancer cells. Tolfenamic acid treatment inhibited cell growth and induced apoptosis as measured by caspase activity and bioelectric impedance. Tolfenamic acid induced EGR-1 expression at the transcription level, and analysis of the EGR-1 promoter showed that a putative ETS-binding site, located at -400 and -394 bp, was required for activation by tolfenamic acid. The electrophoretic mobility shift assay and chromatin immunoprecipitation assay confirmed that this sequence specifically bound to the ETS family protein epithelial-specific ETS-1 (ESE-1) transcription factor. Tolfenamic acid also facilitated translocation of endogenous and exogenous ESE-1 to the nucleus in colorectal cancer cells, and gene silencing using ESE-1 small interfering RNA attenuated tolfenamic acid-induced EGR-1 expression and apoptosis. Overexpression of EGR-1 increased apoptosis and decreased bioelectrical impedance, and silencing of endogenous EGR-1 prevented tolfenamic acid-induced apoptosis. These results show that activation of ESE-1 via enhanced nuclear translocation mediates tolfenamic acid-induced EGR-1 expression, which plays a critical role in the activation of apoptosis.

Alternative medicine products as a novel treatment strategy for inflammatory bowel disease

Inflammatory bowel disease (IBD) affects the mucosal lining of the gastrointestinal tract; the etiology is unknown and treatment is directed at systemic immunosuppression. Natural products, including medicinal herbs, have provided approximately half of the drugs developed for clinical use over the past 20 years. The purpose of our current study was to determine the effects of a novel combination of herbal extracts on intestinal inflammation using a murine model of IBD. Female Swiss-Webster mice were randomized to receive normal water or 5% dextran sulfate sodium (DSS) drinking water to induce colitis. Mice were treated with either a novel combination of herbal aqueous extracts or vehicle control per os (po) or per rectum (pr) every 24 hours for 7-8 days. Disease activity index score (DAI) was determined daily; mice were sacrificed and colons were analyzed by H & E staining, MPO assay, and cytokine (TNF-alpha, IL-6) ELISAs. Mice treated with the combination of herbal extracts, either po or pr, had significantly less rectal bleeding and lower DAI scores compared to the vehicle-treated group. Moreover, colonic ulceration, leukocytic infiltration, and cytokine levels (TNF-alpha and IL-6) were also decreased in the colons of herbal-treated mice, reflected by H & E staining, MPO assay, and cytokine ELISA. Treatment with the combination of medicinal herbs decreases leukocyte infiltration and mucosal ulceration, ameliorating the course of acute colonic inflammation. This herbal remedy may prove to be a novel and safe therapeutic alternative in the treatment of IBD.

Role of cycloxygenase-2 in ulcerative colitis

Cycloxygenase-2 (COX-2) plays an important role in the development and prognosis of ulcerative colitis. First, it may initiate inflammatory process. Many studies show that expression of COX-2 is significantly increased in the lesion of ulcerative colitis. During regenerative phase, inhibition of COX-2 may hinder the healing process, and thereafter exacerbate symptoms. COX-2-induced regeneration is monitored under delicate systems. If the balance of this system is disturbed by unknown factors, dysplasia or even carcinoma may develop.

Anticancer activities of cranberry phytochemicals: an update

Studies employing mainly in vitro tumor models show that extracts and compounds isolated from cranberry fruit (Vaccinium macrocarpon) inhibit the growth and proliferation of several types of tumor including breast, colon, prostate, and lung. Proanthocyanidin oligomers, flavonol and anthocyanin glycosides and triterpenoids are all likely contributors to the observed anticancer properties and may act in a complementary fashion to limit carcinogenesis. Possible chemopreventive mechanisms of action by cranberry phytochemicals include induction of apoptosis in tumor cells, reduced ornithine decarboxylase activity, decreased expression of matrix metalloproteinases associated with prostate tumor metastasis, and anti-inflammatory activities including inhibition of cyclooxygenases. A review of recent studies suggests a potential role for cranberry as a dietary chemopreventive and provides direction for future research.

Cyclooxygenase-2-derived prostaglandin E2 stimulates Id-1 transcription

Cyclooxygenase-2 (COX-2) and Id-1 are overexpressed in a variety of human malignancies. Recently, each of these genes was found to play a role in mediating breast cancer metastasis to the lungs, but their potential interdependence was not evaluated. Hence, the main objective of the current study was to determine whether COX-2-derived prostaglandin (PGE(2)) activated Id-1 transcription, leading in turn to increased invasiveness of mammary epithelial cells. In MDA-MB-231 cells, treatment with PGE(2) induced Id-1, an effect that was mimicked by an EP(4) agonist. PGE(2) via EP(4) activated the epidermal growth factor receptor (EGFR) --> ERK1/2 pathway, which led to increased expression of Egr-1. PGE(2) stimulated EGFR signaling by inducing the release of amphiregulin, an EGFR ligand. The ability of PGE(2) to activate Id-1 transcription was mediated by enhanced binding of Egr-1 to the Id-1 promoter. Silencing of COX-2 or pharmacological inhibition of COX-2 led to reduced PGE(2) production, decreased Id-1 expression, and reduced migration of cells through extracellular matrix. A similar decrease in cell migration was found when Id-1 was silenced. The interrelationship between COX-2, PGE(2), Id-1, and cell invasiveness was also compared in nontumorigenic SCp2 and tumorigenic SCg6 mammary epithelial cells. Consistent with the findings in MDA-MB-231 cells, COX-2-derived PGE(2) induced Id-1, leading in turn to increased cell invasiveness. Taken together, these results suggest that PGE(2) via EP(4) activated the EGFR --> ERK1/2 --> Egr-1 pathway, leading to increased Id-1 transcription and cell invasion. These findings provide new insights into the relationship between COX-2 and Id-1 and their potential role in metastasis.

Gene expression profiling of liver metastases from colorectal cancer as potential basis for treatment choice

At present no reports on gene expression profiling of liver metastases from colorectal cancer are available. We identified two different signatures using Affymetrix platform: epidermal growth factor receptor pathway was upregulated in metachronous lesions, whereas the pathway mainly related to angiogenesis was in synchronous lesions. Synchronous or metachronous liver metastases could be treated differently on the basis of different molecular pathways.

Angiotensin II bi-directionally regulates cyclooxygenase-2 expression in intestinal epithelial cells

We previously demonstrated that angiotensin II (Ang II) receptor signaling is involved in azoxymethane-induced mouse colon tumorigenesis. In order to clarify the role of Ang II in COX-2 expression in the intestinal epithelium, the receptor subtype-specific effect on COX-2 expression in a rat intestinal epithelial cell line (RIE-1) has been investigated. Ang II dose- and time-dependently increased the expression of COX-2, but not COX-1 mRNA and protein. This stimulation was completely blocked by the AT(1) receptor antagonist but not the AT(2) receptor antagonist. Ang II and lipopolysaccharide (LPS) additively induced COX-2 protein in RIE-1 cells, whereas the LPS-induced COX-2 expression was significantly attenuated by low concentrations of Ang II or the AT(2) agonistic peptide CGP-42112A only in AT(2) over-expressed cells. These data indicate that Ang II bi-directionally regulates COX-2 expression via both AT(1) and AT(2) receptors. Control of COX-2 expression through Ang II signaling may have significance in cytokine-induced COX-2 induction and colon tumorigenesis.

Enhanced functionality of CD4+CD25(high)FoxP3+ regulatory T cells in the peripheral blood of patients with prostate cancer

PURPOSE

CD4+CD25(high)FoxP3+ regulatory T cells (Treg) have been shown to inhibit the activation and function of T cells that participate in antigen-specific immune responses. Higher levels of Tregs have been reported in the peripheral blood of patients with several types of tumors. In this study, we investigated the number and functionality of CD4+CD25(high)FoxP3+ Tregs in patients with prostate cancer (PCa), and their potential role in inhibiting antitumor immune responses.

EXPERIMENTAL DESIGN

Levels of Tregs in the peripheral blood of healthy donors and patients with biochemically progressive, localized, and metastatic PCa were each measured by flow cytometry. The functional activity of Tregs was determined by their ability to suppress the proliferation of CD4+CD25- T cells. Data were analyzed using Wilcoxon rank sum test and unpaired Student's t test.

RESULTS

Although levels of Tregs in the peripheral blood of patients with PCa were not significantly higher than those in healthy donors, Tregs in patients with PCa had significantly greater suppressive functionality than Tregs from healthy donors (P < 0.05). Additionally, there was a direct correlation between the serum levels of prostaglandin E(2) and Treg functionality in patients with localized PCa, using Pearson's product-moment correlation coefficient (R).

CONCLUSIONS

These findings further show the potential importance of Tregs in modifying immune responses in patients with PCa. Although longer studies are necessary to confirm these findings, these studies also show for the first time the differences in Treg populations in patients with various stages of PCa, and thus, provide a basis for determining which PCa patient populations are best suited for immunotherapy trials involving the inhibition of Tregs.