Non-steroidol anti-inflammatory drug effect on crypt cell proliferation and apoptosis during initiation of rat colon carcinogenesis

Macroalgal Proteins: A Review

Population growth is the driving change in the search for new, alternative sources of protein. Macroalgae (otherwise known as seaweeds) do not compete with other food sources for space and resources as they can be sustainably cultivated without the need for arable land. Macroalgae are significantly rich in protein and amino acid content compared to other plant-derived proteins. Herein, physical and chemical protein extraction methods as well as novel techniques including enzyme hydrolysis, microwave-assisted extraction and ultrasound sonication are discussed as strategies for protein extraction with this resource. The generation of high-value, economically important ingredients such as bioactive peptides is explored as well as the application of macroalgal proteins in human foods and animal feed. These bioactive peptides that have been shown to inhibit enzymes such as renin, angiotensin-I-converting enzyme (ACE-1), cyclooxygenases (COX), α-amylase and α-glucosidase associated with hypertensive, diabetic, and inflammation-related activities are explored. This paper discusses the significant uses of seaweeds, which range from utilising their anthelmintic and anti-methane properties in feed additives, to food techno-functional ingredients in the formulation of human foods such as ice creams, to utilising their health beneficial ingredients to reduce high blood pressure and prevent inflammation. This information was collated following a review of 206 publications on the use of seaweeds as foods and feeds and processing methods to extract seaweed proteins.

Protective effect of methanol extract of latex of Calotropis procera in an experimental model of colorectal cancer

ETHNOPHARMACOLOGICAL RELEVANCE

The plant, Calotropis procera, has been used for treating various gastrointestinal disorders and cancer. Some of these medicinal properties have been attributed to the latex produced by the plant.

AIM OF THE STUDY

To evaluate the efficacy of methanol extract of air-dried latex (MeDL) of C. procera in the rat model of colorectal cancer (CRC).

MATERIALS AND METHODS

CRC was induced in the rats by 1,2-dimethylhydrazine (DMH) and the effect of MeDL was evaluated at two doses (50 and 150 mg/kg). MeDL and reference drug aspirin (60 mg/kg) were administered orally starting from 1 h before injecting DMH till 8 weeks after the second dose of DMH. The study also included experimental and normal control groups. Microscopic analysis was carried out to determine the count for aberrant crypt foci (ACF) and histology score whereas enzyme-linked immunosorbent assay and immunohistochemical analyses were performed for markers of carcinogenesis and angiogenesis. Other parameters that were evaluated include deoxyribonucleic acid (DNA) fragmentation, laddering, Bcl₂ and Bax immunoreactivity, and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) positivity.

RESULTS

Subcutaneous injection of DMH induced pre-neoplastic changes in the colon of rats with the appearance of ACF with multiple crypts (1-3, 4-6 or >6). In the experimental control group, total ACF count was 3.49 ± 0.23/cm of the colon length and the median histology score was 2.0 for architectural abnormalities, 2.0 for dilatation of crypts and 1.5 for hyperplasia/dysplasia against 1.0 for all the characteristics in normal rats. Oral administration of MeDL similar to aspirin, led to a reduction in ACF count and histology score of CRC concomitant with a decrease in the levels of markers of carcinogenesis - β-catenin and proliferating cell nuclear antigen (PCNA); markers of angiogenesis - matrix metallopeptidase-9 (MMP-9) and vascular endothelial growth factor (VEGF), and an increase in apoptotic DNA fragmentation.

CONCLUSION

MeDL confers protection in the rat model of CRC and the study suggests its therapeutic potential in this condition.

Antimicrobial, cytotoxicity, molecular modeling and DNA cleavage/binding studies of zinc-naproxen complex: switching DNA binding mode of naproxen by coordination to zinc ion

The intercalation DNA binding mode of the naproxen, a non-steroidal anti-inflammatory drug, has been reported previously. In this study, calf thymus deoxyribonucleic acid (CT-DNA) binding of zinc-naproxen complex, [Zn(naproxen)₂(MeOH)₂], at physiological pH has been investigated by multi-spectroscopic techniques and molecular docking. Zinc-naproxen complex displays significant binding property to the CT-DNA (K_b = 0.2 × 10⁵ L.mol^-1). All of the experimental results; relative increasing in viscosity of CT-DNA and fluorimetric studies using ethidium bromide (EB) and Hoechst 33258 probes, are indicative of groove binding mode of zinc-naproxen complex to CT-DNA. These results show that the coordination of naproxen to zinc metal switches the mode of binding from intercalation to groove. The molecular modeling also shows that the complex binds to the AT-rich region of minor groove of DNA. Structural and topography changes of DNA in interaction with the complex by atomic force microscopy (AFM) indicated that CT-DNA becomes swollen after interaction. The pUC18 plasmid DNA cleavage ability of zinc-naproxen complex by gel electrophoresis experiments revealed that zinc-naproxen complex cleaved supercoiled pUC18 plasmid DNA to nicked DNA. The cytotoxicity of the zinc complex performed by MTT method on HT29 and MCF7 cancer cell lines and on HEK 293 normal cell lines indicates that zinc complex has no cytotoxic effect on both HT29 and MCF7 cell lines but has better cytotoxicity effect on HEK 293 cell lines compared to cisplatin standard drug. The antimicrobial activity of the complex against Staphylococcus aureus and Escherichia coli bacteria revealed the high antimicrobial activity of the complex.Communicated by Ramaswamy H. Sarma.

Prostaglandin-endoperoxide synthase 2 (cyclooxygenase-2), a complex target for colorectal cancer prevention and therapy

A plentiful literature has linked colorectal cancer (CRC) to inflammation and prostaglandin-endoperoxide synthase (PTGS)2 expression. Accordingly, several nonsteroidal antiinflammatory drugs (NSAIDs) have been tested often successfully in CRC chemoprevention despite their different ability to specifically target PTGS2 and the low or null expression of PTGS2 in early colon adenomas. Some observational studies showed an increased survival for patients with CRC assuming NSAIDs after diagnosis, but no clinical trial has yet demonstrated the efficacy of NSAIDs against established CRC, where PTGS2 is expressed at high levels. The major limits for the application of NSAIDs, or specific PTGS2 inhibitors, as adjuvant drugs in CRC are (1) a frequent confusion about the physiological role of PTGS1 and PTGS2, reflecting in CRC pathology and therapy; (2) the presence of unavoidable side effects linked to the intrinsic function of these enzymes; (3) the need of established criteria and markers for patient selection; and (4) the evaluation of the immunomodulatory potential of PTGS2 inhibitors as possible adjuvants for immunotherapy. This review has been written to rediscover the multifaceted potential of PTGS2 targeting, hoping it could act as a starting point for a new and more aware application of NSAIDs against CRC.

Chemoprevention by artesunate in a preclinical model of colorectal cancer involves down regulation of β-catenin, suppression of angiogenesis, cellular proliferation and induction of apoptosis

Use of anti-inflammatory drugs is well known to decrease the risk of colorectal cancer, one of the most common causes of cancer related mortality. In view of anti-inflammatory property of artesunate reported in various experimental models, the present study was carried out to evaluate its efficacy in rat model where colon carcinogenesis was induced by 1, 2 dimethylhydrazine (DMH). A time course study revealed that two injections of DMH given at an interval of one week resulted in appearance of multiple plaque lesions and aberrant crypt foci in the colon with a peak effect occurring at the end of 8 weeks. An efficacy study carried out with daily oral administration of artesunate (50 and 150 mg/kg) and aspirin (60 mg/kg) showed a marked reduction in pre-neoplastic changes with a significant decrease in the number of aberrant crypt foci, crypt multiplicity and restoration of histoarchitecture. Both the drugs down regulated β-catenin signaling, reduced the levels of angiogenic markers like VEGF, MMP-9 and inhibited cellular proliferation. The anti-cancer effect of these drugs was concomitant with the pro-apoptotic effect as revealed by increased DNA fragmentation, TUNEL positivity and Bax/Bcl₂ immunoreactivity. This is the first study to evaluate the inhibitory effect of artesunate on pre-neoplastic changes in colon where its chemopreventive effect was found to be comparable to that of aspirin. Our study strengthens the previous findings and shows that it has a preventive and therapeutic potential in the treatment of colon cancer.

Epigenetic impact of infection on carcinogenesis: mechanisms and applications

Viral and bacterial infections are involved in the development of human cancers, such as liver, nasopharyngeal, cervical, head and neck, and gastric cancers. Aberrant DNA methylation is frequently present in these cancers, and some of the aberrantly methylated genes are causally involved in cancer development and progression. Notably, aberrant DNA methylation can be present even in non-cancerous or precancerous tissues, and its levels correlate with the risk of cancer development, producing a so-called 'epigenetic field for cancerization'. Mechanistically, most viral or bacterial infections induce DNA methylation indirectly via chronic inflammation, but recent studies have indicated that some viruses have direct effects on the epigenetic machinery of host cells. From a translational viewpoint, a recent multicenter prospective cohort study demonstrated that assessment of the extent of alterations in DNA methylation in non-cancerous tissues can be used to predict cancer risk. Furthermore, suppression of aberrant DNA methylation was shown to be a useful strategy for cancer prevention in an animal model. Here, we review the involvement of aberrant DNA methylation in various types of infection-associated cancers, along with individual induction mechanisms, and we discuss the application of these findings for cancer prevention, diagnosis, and therapy.

CDK/CCN and CDKI alterations for cancer prognosis and therapeutic predictivity

The regulation of cell growth and division occurs in an accurate sequential manner. It is dictated by the accumulation of cyclins (CCNs) and cyclin-dependent kinases (CDKs) complexes and degradation of CCNs. In human tumors, instead, the cell cycle is deregulated, causing absence of differentiation and aberrant cell growth. Oncogenic alterations of CCNs, CDKs, and CDKIs have been reported in more than 90% of human cancers, and the most frequent are those related to the G1 phase. Several molecular mechanisms, including gene overexpression, chromosomal translocations, point mutations, insertions and deletions, missense and frame shift mutation, splicing, or methylation, may be responsible for these alterations. The cell cycle regulators are involved in tumor progression given their association with cancers characterized by higher incidence of relapses and chemotherapy resistance. In the last decade anticancer drug researches focused on new compounds, able to target molecules related to changes in genes associated with tumor status. Recently, the studies have focused on the restoration of cell cycle control modulating molecular targets involved in cancer-cell alterations. This paper aims to correlate alterations of cell cycle regulators with human cancers and therapeutic responsivity.

Sulindac modulates secreted protein expression from LIM1215 colon carcinoma cells prior to apoptosis

Colorectal cancer (CRC) is a major cause of mortality in Western populations. Growing evidence from human and rodent studies indicate that nonsteroidal anti-inflammatory drugs (NSAIDs) cause regression of existing colon tumors and act as effective chemopreventive agents in sporadic colon tumor formation. Although much is known about the action of the NSAID sulindac, especially its role in inducing apoptosis, mechanisms underlying these effects is poorly understood. In previous secretome-based proteomic studies using 2D-DIGE/MS and cytokine arrays we identified over 150 proteins released from the CRC cell line LIM1215 whose expression levels were dysregulated by treatment with 1mM sulindac over 16h; many of these proteins are implicated in molecular and cellular functions such as cell proliferation, differentiation, adhesion, angiogenesis and apoptosis (Ji et al., Proteomics Clin. Appl. 2009, 3, 433-451). We have extended these studies and describe here an improved protein/peptide separation strategy that facilitated the identification of 987 proteins and peptides released from LIM1215 cells following 1mM sulindac treatment for 8h preceding the onset of apoptosis. This peptidome separation strategy involved fractional centrifugal ultrafiltration of concentrated cell culture media (CM) using nominal molecular weight membrane filters (NMWL 30K, 3K and 1K). Proteins isolated in the >30K and 3-30K fractions were electrophoretically separated by SDS-PAGE and endogenous peptides in the 1-3K membrane filter were fractioned by RP-HPLC; isolated proteins and peptides were identified by nanoLC-MS-MS. Collectively, our data show that LIM1215 cells treated with 1mM sulindac for 8h secrete decreased levels of proteins associated with extracellular matrix remodeling (e.g., collagens, perlecan, syndecans, filamins, dyneins, metalloproteinases and endopeptidases), cell adhesion (e.g., cadherins, integrins, laminins) and mucosal maintenance (e.g., glycoprotein 340 and mucins 5AC, 6, and 13). A salient finding of this study was the increased proteolysis of cell surface proteins following treatment with sulindac for 8h (40% higher than from untreated LIM1215 cells); several of these endogenous peptides contained C-terminal amino acids from transmembrane domains indicative of regulated intramembrane proteolysis (RIP). Taken together these results indicate that during the early-stage onset of sulindac-induced apoptosis (evidenced by increased annexin V binding, dephosphorylation of focal adhesion kinase (FAK), and cleavage of caspase-3), 1mM sulindac treatment of LIM1215 cells results in decreased expression of secreted proteins implicated in ECM remodeling, mucosal maintenance and cell-cell-adhesion. This article is part of a Special Issue entitled: An Updated Secretome.

Ibuprofen delivered by poly(lactic-co-glycolic acid) (PLGA) nanoparticles to human gastric cancer cells exerts antiproliferative activity at very low concentrations

PURPOSE

Epidemiological, clinical, and laboratory studies have suggested that ibuprofen, a commonly used nonsteroidal anti-inflammatory drug, inhibits the promotion and proliferation of certain tumors. Recently, we demonstrated the antiproliferative effects of ibuprofen on the human gastric cancer cell line MKN-45. However, high doses of ibuprofen were required to elicit these antiproliferative effects in vitro. The present research compared the antiproliferative effects of ibuprofen delivered freely and released by poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) in MKN-45 cells.

METHODS

MKN-45 human gastric adenocarcinoma cells were treated with ibuprofen-loaded PLGA NPs. The proliferation of MKN-45 cells was then assessed by cell counting. The uptake of NPs was imaged by fluorescence microscopy and flow cytometry. The release of ibuprofen from ibuprofen-loaded PLGA NPs in the cells was evaluated by gas chromatography-mass spectrometry.

RESULTS

Dramatic inhibition of cellular proliferation was observed in cells treated with ibuprofen-loaded PLGA NPs versus those treated with free ibuprofen at the same concentration. The localization of NPs was cytoplasmic. The initiation of ibuprofen release was rapid, commencing within 2 hours, and then increased slowly over time, reaching a maximum concentration at 24 hours. The inhibition of proliferation was confirmed to be due to the intracellular release of ibuprofen from the NPs. Using PLGA NPs as carriers, ibuprofen exerted an antiproliferative activity at concentrations > 100 times less than free ibuprofen, suggesting greater efficiency and less cellular toxicity. In addition, when carried by PLGA NPs, ibuprofen more quickly induced the expression of transcripts involved in proliferation and invasiveness processes.

CONCLUSION

Ibuprofen exerted an antiproliferative effect on MKN-45 cells at low concentrations. This effect was achieved using PLGA NPs as carriers of low doses of ibuprofen.

Glucans from the edible mushroom Pleurotus pulmonarius inhibit colitis-associated colon carcinogenesis in mice

BACKGROUND

We have recently demonstrated that polysaccharides from fruiting body extract (FBE) or mycelia extract (ME) of the edible mushroom Pleurotus pulmonarius exert antiproliferative effects in intestinal cells and an anti-inflammatory effect in a dextran sulfate sodium (DSS) mouse model of acute colitis. The aim of this study was to assess the role of fungal FBE and ME in colon carcinogenesis.

METHODS

In vitro, human colorectal cancer cells were treated with FBE and ME and analyzed for inflammation response, for markers of apoptosis, and for cell-cycle progression. In vivo, FBE and ME were tested in a mouse model of colitis-associated colorectal carcinogenesis induced by cyclic treatments with DSS and azoxymethane. Treated mice were fed a daily diet containing 2 or 20 mg FBE or ME per mouse for 80 days.

RESULTS

In vitro, FBE and ME induced apoptosis in a dose-responsive manner and modulated the expression of Bcl-2, Bax, and cytochrome c, and blocked tumor necrosis factor (TNF)-α-induced inhibitor of nuclear factor (NF) (Iκ)-Bα degradation and NF-κB nuclear translocation. In vivo, dietary administration of FBE and ME significantly reduced the formation of aberrant crypt foci, which precedes colorectal cancer, and of microadenomas. The treatments significantly lowered the expression of proliferating cell nuclear antigen and increased the number of cells undergoing apoptosis in the colon. Additionally, FBE and ME inhibited the expression of the proinflammatory cytokine TNF-α in colonic tissue.

CONCLUSIONS

We conclude that P. pulmonarius FBE and ME inhibit colitis-associated colon carcinogenesis induced in mice through the modulation of cell proliferation, induction of apoptosis, and inhibition of inflammation.

Multivitamin and mineral supplementation in 1,2-dimethylhydrazine induced experimental colon carcinogenesis and evaluation of free radical status, antioxidant potential, and incidence of ACF

This study was performed to determine the chemopreventive and antioxidant status of multivitamin and mineral (0.01% in drinking water, ad libitum) supplements in 1,2-dimethylhydrazine (DMH)-induced experimental colon carcinogenesis. Experimental colon carcinogenesis was induced in male albino Wistar rats by injecting DMH (20 mg·(kg body mass)–1) once weekly for 15 consecutive weeks, and administering a multivitamin supplement in 3 regimes (initiation, post-initiation, and entire experimental period) for 32 weeks. We studied lipid peroxidation products (thiobarbituric acid reactive substances, lipid hydroperoxides, conjugated dienes) in the circulation and in the tissues, antioxidant status (superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, and non-enzymatic antioxidant-reduced glutathione) of the tissues, aberrant crypt foci (ACF), and histopathological alterations. DMH-induced rats had an increase in lipid peroxidation products and a lower antioxidant status compared with control animals. Multivitamin and mineral supplementation during the initiation, post-initiation, and the entire study period significantly decreased the levels of lipid peroxidation products in circulation and colonic tissues, significantly elevated the activities of the antioxidant enzymes and reduced glutathione to near normalcy in DMH-induced rats. The incidence of ACF was reduced to 84.1% in rats supplemented with multivitamin and minerals for the entire study and prevented the colonic tissue from histopathological alterations induced by DMH.

Non-steroidal anti-inflammatory drugs and colorectal cancer risk in a large, prospective cohort

OBJECTIVES

Use of non-steroidal anti-inflammatory drugs (NSAIDs) has been inversely associated with colorectal cancer; however, the association within colorectal subsites or among higher risk individuals is understudied. We investigated NSAID use and colorectal adenocarcinoma by subsite, and among individuals with a family history of colon cancer in the National Institutes of Health-AARP Diet and Health Study.

METHODS

Using Cox proportional hazards regression, we estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for colorectal cancer incidence among 301,240 men and women (mean age 62.8 years); including 26,994 individuals with a first-degree relative with a history of colon cancer. We accrued 3,894 colorectal cancer cases during 10 years of follow-up; 372 cases had a first-degree relative with colon cancer.

RESULTS

Both aspirin and non-aspirin NSAID use reduced colorectal cancer risk (HR for users compared with non-users=0.91, 95% CI: 0.85, 0.98; HR=0.82, 95% CI: 0.77, 0.87, respectively). Daily aspirin use reduced the risk of cancer in the distal colon (HR=0.84, 95% CI: 0.71, 0.99) and rectum (HR=0.76, 95% CI: 0.64, 0.90); daily non-aspirin NSAID use reduced the risk of both proximal (HR=0.65, 95% CI: 0.54, 0.78) and distal colon cancer (HR=0.69, 95% CI: 0.55, 0.87), but not rectal cancer. Among participants with a first-degree relative with colon cancer, daily use of aspirin was associated with a decreased risk of rectal cancer (HR=0.38, 95% CI: 0.19, 0.78), and daily use of non-aspirin NSAIDs was associated with a decreased risk of colon cancer (HR=0.49, 95% CI: 0.29, 0.82). No protective benefit for daily aspirin use and colon cancer or daily non-aspirin NSAID use and rectal cancer was observed in this higher risk subgroup, although power was limited by small case numbers.

CONCLUSIONS

NSAID use was associated with a reduced colorectal cancer risk; the magnitude of this association differed between aspirin and non-aspirin NSAIDs. Daily aspirin and non-aspirin NSAID use by individuals with a family history of colon cancer significantly reduced the risk of rectal and colon cancer, respectively.

Non-steroidal anti-inflammatory drugs and colorectal cancer risk in a large, prospective cohort

OBJECTIVES

Use of non-steroidal anti-inflammatory drugs (NSAIDs) has been inversely associated with colorectal cancer; however, the association within colorectal subsites or among higher risk individuals is understudied. We investigated NSAID use and colorectal adenocarcinoma by subsite, and among individuals with a family history of colon cancer in the National Institutes of Health-AARP Diet and Health Study.

METHODS

Using Cox proportional hazards regression, we estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for colorectal cancer incidence among 301,240 men and women (mean age 62.8 years); including 26,994 individuals with a first-degree relative with a history of colon cancer. We accrued 3,894 colorectal cancer cases during 10 years of follow-up; 372 cases had a first-degree relative with colon cancer.

RESULTS

Both aspirin and non-aspirin NSAID use reduced colorectal cancer risk (HR for users compared with non-users=0.91, 95% CI: 0.85, 0.98; HR=0.82, 95% CI: 0.77, 0.87, respectively). Daily aspirin use reduced the risk of cancer in the distal colon (HR=0.84, 95% CI: 0.71, 0.99) and rectum (HR=0.76, 95% CI: 0.64, 0.90); daily non-aspirin NSAID use reduced the risk of both proximal (HR=0.65, 95% CI: 0.54, 0.78) and distal colon cancer (HR=0.69, 95% CI: 0.55, 0.87), but not rectal cancer. Among participants with a first-degree relative with colon cancer, daily use of aspirin was associated with a decreased risk of rectal cancer (HR=0.38, 95% CI: 0.19, 0.78), and daily use of non-aspirin NSAIDs was associated with a decreased risk of colon cancer (HR=0.49, 95% CI: 0.29, 0.82). No protective benefit for daily aspirin use and colon cancer or daily non-aspirin NSAID use and rectal cancer was observed in this higher risk subgroup, although power was limited by small case numbers.

CONCLUSIONS

NSAID use was associated with a reduced colorectal cancer risk; the magnitude of this association differed between aspirin and non-aspirin NSAIDs. Daily aspirin and non-aspirin NSAID use by individuals with a family history of colon cancer significantly reduced the risk of rectal and colon cancer, respectively.

Spectroscopic studies of the interaction of aspirin and its important metabolite, salicylate ion, with DNA, A·T and G·C rich sequences

Among different biological effects of acetylsalicylic acid (ASA), its anticancer property is controversial. Since ASA hydrolyzes rapidly to salicylic acid (SA), especially in the blood, interaction of both ASA and SA (as the small molecules) with ctDNA, oligo(dA·dT)15 and oligo(dG·dC)15, as a possible mechanism of their action, is investigated here. The results show that the rate of ASA hydrolysis in the absence and presence of ctDNA is similar. The spectrophotometric results indicate that both ASA and SA cooperatively bind to ctDNA. The binding constants (K) are (1.7±0.7)×10(3) M(-1) and (6.7±0.2)×10(3) M(-1) for ASA and SA, respectively. Both ligands quench the fluorescence emission of ethidium bromide (Et)-ctDNA complex. The Scatchard plots indicate the non-displacement based quenching (non-intercalative binding). The circular dichroism (CD) spectra of ASA- or SA-ctDsNA complexes show the minor distortion of ctDNA structure, with no characteristic peaks for intercalation of ligands. Tm of ctDNA is decreased up to 3°C upon ASA binding. The CD results also indicate more distortions on oligo(dG·dC)15 structure due to the binding of both ASA and SA in comparison with oligo(dA·dT)15. All data indicate the more affinity for SA binding with DNA minor groove in comparison with ASA which has more hydrophobic character.

15-Hydroxyprostaglandin dehydrogenase (15-PGDH) is up-regulated by flurbiprofen and other non-steroidal anti-inflammatory drugs in human colon cancer HT29 cells

Non-steroidal anti-inflammatory drugs (NSAIDs) are known to inhibit prostaglandin synthetic enzyme, cyclooxygenases (COXs), as well as to exhibit anti-tumor activity although at much higher concentrations. 15-Hydroxyprostaglandin dehyrogenase (15-PGDH), a key prostaglandin catabolic enzyme, was recently shown to be a tumor suppressor. Effects of NSAIDs on 15-PGDH expression were therefore examined. Flurbiprofen and several other NSAIDs were found to induce 15-PGDH expression in human colon cancer HT29 cells. Flurbiprofen, the most active one, was also shown to induce 15-PGDH expression in other types of cancer cells. Induction of 15-PGDH expression appeared to occur at the stage of mRNA as levels of 15-PGDH mRNA were increased by flurbiprofen in HT29 cells. Levels of 15-PGDH were also found to be regulated at the stage of protein turnover. MEK inhibitors, PD98059 and U-0126, which inhibited ERK phosphorylation were shown to elevate 15-PGDH levels very significantly. These inhibitors did not appear to alter 15-PGDH mRNA levels but down-regulate matrix metalloproteinase-9 (MMP-9). This protease was shown to degrade and inactivate 15-PGDH suggesting that elevation of 15-PGDH levels could be due to inhibition of MMP-9 expression by these inhibitors. Similarly, flurbiprofen was also demonstrated to inhibit ERK activation and to down-regulate MMP-9 expression. Furthermore, flurbiprofen was shown to induce the expression of tissue inhibitor of metalloproteinase-1 (TIMP-1), an inhibitor of MMP-9. The turnover of 15-PGDH was found to prolong in the presence of flurbiprofen as compared to that in the absence of this drug. Taken together, these results indicate that flurbiprofen up-regulates 15-PGDH by increasing the expression and decreasing the degradation of 15-PGDH in HT29 cells.

Suppression of implanted MDA-MB 231 human breast cancer growth in nude mice by dietary walnut

Walnuts contain components that may slow cancer growth including omega 3 fatty acids, phytosterols, polyphenols, carotenoids, and melatonin. A pilot study was performed to determine whether consumption of walnuts could affect growth of MDA-MB 231 human breast cancers implanted into nude mice. Tumor cells were injected into nude mice that were consuming an AIN-76A diet slightly modified to contain 10% corn oil. After the tumors reached 3 to 5 mm diameter, the diet of one group of mice was changed to include ground walnuts, equivalent to 56 g (2 oz) per day in humans. The tumor growth rate from Day 10, when tumor sizes began to diverge, until the end of the study of the group that consumed walnuts (2.9 +/- 1.1 mm(3)/day; mean +/- standard error of the mean) was significantly less (P > 0.05, t-test of the growth rates) than that of the group that did not consume walnuts (14.6 +/- 1.3 mm(3)/day). The eicosapentaenoic and docosahexaenoic acid fractions of the livers of the group that consumed walnuts were significantly higher than that of the group that did not consume walnuts. Tumor cell proliferation was decreased, but apoptosis was not altered due to walnut consumption. Further work is merited to investigate applications to cancer in humans.

Nonsteroidal anti-inflammatory drug use after 3 years of aspirin use and colorectal adenoma risk: observational follow-up of a randomized study

BACKGROUND

Frequent use of nonsteroidal anti-inflammatory drugs (NSAIDs) has been shown to reduce the risk of colorectal adenomas in randomized trials. We examined the persistence of the protective effect after the cessation of randomized aspirin treatment and whether it is affected by the duration and frequency of subsequent NSAID use.

METHODS

We used data from the Aspirin/Folate Polyp Prevention Study (AFPPS), in which 1121 subjects were randomly assigned to receive placebo or aspirin (81 or 325 mg/d) for 3 years. After the end of treatment and a follow-up colonoscopy, AFPPS participants were invited to remain under follow-up until their next surveillance colonoscopies, scheduled 3-5 years later. Information regarding use of NSAIDs during posttreatment follow-up was gathered periodically via questionnaires. Average weekly NSAID use was classified as sporadic (<2 days per week), moderate (2 to <4 days per week), or frequent (>or=4 days per week). The analysis was stratified according to randomized aspirin groups and posttreatment NSAID use; placebo subjects who later were sporadic NSAID users formed the reference group. The primary outcomes were all adenomas and advanced lesions. Adjusted relative risks and 95% confidence intervals were computed with generalized linear models. All statistical tests were two-sided.

RESULTS

A total of 850 subjects underwent a posttreatment colonoscopy, on average 4 years after the end of study treatment. The protective effect of 81 mg of aspirin for colorectal adenomas persisted with continued posttreatment NSAID use. The risk of any adenoma among frequent NSAID users was 26.8% vs 39.9% among placebo subjects who later used NSAIDs sporadically (adjusted relative risk = 0.62, 95% confidence interval [CI] = 0.39 to 0.98; P(trend) with NSAID use frequency = .03). The unadjusted absolute risk reduction was 13.1 percentage points (95% CI = -0.3 to 26.5 percentage points) (P = .07). Results for 325 mg of aspirin were similar, although not statistically significant. For advanced lesions, small numbers of endpoints limited the analysis, but findings among subjects randomly assigned to 81 mg of aspirin suggested a protective association regardless of posttreatment NSAID use.

CONCLUSION

Long-term and frequent use of NSAIDs may enhance the chemopreventive effect of aspirin against colorectal neoplasia.

Intrinsic resistance to apoptosis of colon epithelial cells is a potential determining factor in the susceptibility of the A/J mouse strain to dimethylhydrazine-induced colon tumorigenesis

Alterations in the delicate balance between cell proliferation and cell death disrupt colon homeostasis and serve as determining factors in colon tumorigenesis. The two mouse strains, AKR/J (resistant) and A/J (susceptible), have been widely used as models for dimethylhydrazine-induced colon tumorigenesis. This study examined whether the differential susceptibilities of the two mouse strains to the tumorigenic effect of dimethylhydrazine were associated with intrinsic differences in the apoptotic machinery of the colon epithelial cells. While acute exposure to dimethylhydrazine caused massive apoptosis of colon epithelial cells in AKR/J mice, the effect was considerably less in A/J mice. Apoptosis in AKR/J mice occurred not only in the luminal side of the mucosa but also deep in the colonic crypts. In addition, this apoptosis appeared to involve caspase-3. The increased sensitivity of AKR/J to dimethylhydrazine was associated with a persistent expression of tumor necrosis factor (TNF) but not of its receptors. After establishing a new method for isolating primary colon epithelial cells, we determined that cells derived from A/J mice were substantially more resistant to apoptosis in response to dimethylhydrazine or to a combination of TNF, cyclohexamide, and butyrate compared to cells from AKR/J mice. These results strongly suggest that a higher intrinsic resistance to apoptosis of colon epithelial cells may be an important determinant of predisposition to colon tumorigenesis in the A/J mouse strain.

Nicotine induces cyclooxygenase-2 and vascular endothelial growth factor receptor-2 in association with tumor-associated invasion and angiogenesis in gastric cancer

Blockade of angiogenesis is a promising strategy to suppress tumor growth, invasion, and metastasis. Vascular endothelial growth factor (VEGF), which binds to tyrosine kinase receptors [VEGF receptors (VEGFR) 1 and 2], is the mediator of angiogenesis and mitogen for endothelial cells. Cyclooxygenase-2 (COX-2) plays an important role in the promoting action of nicotine on gastric cancer growth. However, the action of nicotine and the relationship between COX-2 and VEGF/VEGFR system in tumorigenesis remain undefined. In this study, the effects of nicotine in tumor angiogenesis, invasiveness, and metastasis were studied with sponge implantation and Matrigel membrane models. Nicotine (200 microg/mL) stimulated gastric cancer cell proliferation, which was blocked by SC-236 (a highly selective COX-2 inhibitor) and CBO-P11 (a VEGFR inhibitor). This was associated with decreased VEGF levels as well as VEGFR-2 but not VEGFR-1 expression. Topical injection of nicotine enhanced tumor-associated vascularization, with a concomitant increase in VEGF levels in sponge implants. Again, application of SC-236 (2 mg/kg) and CBO-P11 (0.4 mg/kg) partially attenuated vascularization by approximately 30%. Furthermore, nicotine enhanced tumor cell invasion through the Matrigel membrane by 4-fold and promoted migration of human umbilical vein endothelial cells in a cocultured system with gastric cancer cells. The activity of matrix metalloproteinases 2 and 9 and protein expressions of plasminogen activators (urokinase-type plasminogen activator and its receptor), which are the indicators of invasion and migration processes, were increased by nicotine but blocked by COX-2 and VEGFR inhibitors. Taken together, our results reveal that the promoting action of nicotine on angiogenesis, tumor invasion, and metastasis is COX-2/VEGF/VEGFR dependent.

Relation between Cyclooxygenase-2 Expression and Clinicopathologic Parameters with Patient Prognosis in Transitional Cell Carcinoma of the Bladder

OBJECTIVE

To evaluate the correlation between cyclooxygenase-2 (Cox-2) expression and clinicopathologic findings with the effect of these variables on prognosis of bladder cancer.

METHODS

Cox-2 expression was examined immunohistochemically in paraffin blocks of 99 patients. Correlations between Cox-2 expression and variables like cancer stage and grade, number of mitoses, angiolymphatic invasion, number and size of the lesions were determined.

RESULTS

Cox-2 expression was detected in 52 (52.5%) patients. Univariate regression analysis between Cox-2 expression and clinicopathologic findings showed a significant correlation only in the pathologic stage of the patients (p = 0.048) (OR =2.64, CI = 0.97-7.81). Multivariate regression analysis in stage T1 revealed an increasing number of mitoses as an independent prognostic factor for recurrence (p = 0.002) (OR = 1.5, CI = 1.16-1.92) and progression (p = 0.030) (OR = 8.23, CI = 1.22-55.27) although a prognostic factor was not found for progression in stage T2.

CONCLUSION

Univariate analysis showed that only the pathologic stage correlated significantly with Cox-2 expression. Cox-2 expression revealed a significant relation with patient prognosis in stage T2 but not in stage T1. These results support the fact that Cox-2 inhibitors may play a role in progression of invasive bladder tumors.

Interaction of Calcium Supplementation and Nonsteroidal Anti-inflammatory Drugs and the Risk of Colorectal Adenomas

BACKGROUND

Calcium and aspirin have both been found to be chemopreventive against colorectal neoplasia. However, the joint effect of the two agents has not been well investigated.

METHODS

To explore the separate and joint effects of calcium and aspirin/nonsteroidal anti-inflammatory drugs (NSAID), we used data from two large randomized clinical trials among patients with a recent history of colorectal adenomas. In the Calcium Polyp Prevention Study, 930 eligible subjects were randomized to receive placebo or 1,200 mg of elemental calcium daily for 4 years. In the Aspirin/Folate Polyp Prevention Study, 1,121 eligible subjects were assigned to take placebo, 81 mg of aspirin, or 325 mg of aspirin daily for 3 years. In each study, subjects completed a validated food frequency questionnaire at enrollment and were asked periodically about medications and supplements used. Recurrent adenomas and advanced adenomas were the end points considered. We used generalized linear models to assess the separate and combined effects of aspirin (or NSAIDs) and calcium supplementation (or dietary calcium) and the interactions between these exposures.

RESULTS

In the Calcium Trial, subjects randomized to calcium who also were frequent users of NSAIDs had a reduction of risk for advanced adenomas of 65% [adjusted risk ratio (RR), 0.35; 95% confidence interval (95% CI), 0.13-0.96], and there was a highly significant statistical interaction between calcium treatment and frequent NSAID use (P(interaction) = 0.01). Similarly, in the Aspirin Trial, 81 mg aspirin and calcium supplement use together conferred a risk reduction of 80% for advanced adenomas (adjusted RR, 0.20; 95% CI, 0.05-0.81); there was a borderline significant statistical interaction between the two treatments (P(interaction) = 0.09). In this trial, we found similar trends when we considered baseline dietary calcium intake instead of calcium supplements. For all adenomas considered together, the interactive patterns were not consistent.

CONCLUSION

Data from two different randomized clinical trials suggest that calcium and NSAIDs may act synergistically to lower the risk of advanced colorectal neoplastic polyps.

Absence of acute apoptotic response to genotoxic carcinogens in p53-deficient mice is associated with increased susceptibility to azoxymethane-induced colon tumours

Acute apoptotic response to genotoxic carcinogens (AARGC) might be important for controlling the consequences of mutational load in the colon. It has been shown to occur in parallel with activation of DNA repair mechanisms. Inadequate AARGC might allow development of mutated clones with the potential to progress to cancer. In this study, we tested if p53 levels were important for AARGC in the colon and whether defective AARGC was associated with increased risk for colorectal oncogenesis. Apoptosis was measured in colonic epithelium of mice from each p53 genotype (p53-/-, p53+/-, wild-type) without and 8 hr following a single injection of azoxymethane (AOM). To determine risk for carcinogen-induced colorectal cancer (CRC), groups of mice from each p53 genotype received 3 weekly injections of AOM and colons were examined for tumour 20 weeks later. Rates of spontaneous apoptosis in colon were not affected by p53 level. However, AARGC was absent in p53-/- mice and reduced by 50% in p53+/- mice (both p < 0.01) compared to wild-type mice. AOM induced tumours in 30% of wild-type mice (average multiplicity 1.0 tumours/mouse) compared to 72% of p53+/- mice (2.0 tumours/mouse, p < 0.01) and 100% of p53-/- mice (2.8 tumours/mouse, p < 0.01). Without AOM, significantly fewer mice in all groups had tumours. Rates of apoptosis in tumours were independent of p53 status. p53 dysfunction puts intestinal epithelia at increased risk of genotoxin-induced oncogenesis due to impairment of apoptotic response mechanisms. p53 levels do not appear, however, to be important for spontaneous apoptosis in normal epithelium or apoptosis in tumours. Subsequent studies are now warranted to test the converse, namely, that enhanced apoptotic response to carcinogen reduces risk for colorectal oncogenesis.

Helicobacter pylori promote gastric cancer cells invasion through a NF-kB and COX-2-mediated pathway

AIM: To examine the effects of Helicobacter pylori (H pylori) infection on the invasiveness of gastric cancer cells, and to elucidate its mechanism.

METHODS: Gastric carcinoma cells, MKN-45, were incubated with CagA-positive H pylori, and cell invasion was determined by Matrigel analysis. The expression of matrix metallopr-oteinase-9 (MMP-9), vascular endothelial growth factor (VEGF), and cyclooxygenase-2 (COX-2) were assessed by Western-blot analysis, and transcriptional activation of the COX-2 promoter was examined by measuring luciferase and β-galactosidase activities. Lastly, the protein-DNA interaction was confirmed by an electrophoretic mobility shift assay.

RESULTS: The current studies showed that: (1) incubation of CagA-positive H pylori with MKN-45 cells significantly promotes gastric cancer cells invasion, and this effect is attenuated by pre-treatment with NS-398, a COX-2 inhibitor, or PDTC, a nuclear factor κB (NF-κB) inhibitor; (2) the induction of MKN-45 cells invasion by H pylori is associated with increases in COX-2, MMP-9, and VEGF protein expression, and co-incubation of NS-398 or PDTC significantly reduces these effects; (3) H pylori infection transactivates COX-2 promoter activity and increases the binding of NF-κB to this promoter.

CONCLUSION: Our data demonstrate that H pylori infection promotes gastric epithelial cells invasion by activating MMP-9 and VEGF expression. These effects appear to be mediated through a NF-κB and COX-2 mediated pathway, as COX-2 or NF-κB inhibitor significantly attenuate the invasiveness of gastric cancer cells and the expressions of MMP-9 and VEGF protein.

Suppression of colitis-related mouse colon carcinogenesis by a COX-2 inhibitor and PPAR ligands

Background

It is generally assumed that inflammatory bowel disease (IBD)-related carcinogenesis occurs as a result of chronic inflammation. We previously developed a novel colitis-related mouse colon carcinogenesis model initiated with azoxymethane (AOM) and followed by dextran sodium sulfate (DSS). In the present study we investigated whether a cyclooxygenase (COX)-2 inhibitor nimesulide and ligands for peroxisome proliferator-activated receptors (PPARs), troglitazone (a PPARγ ligand) and bezafibrate (a PPARα ligand) inhibit colitis-related colon carcinogenesis using our model to evaluate the efficacy of these drugs in prevention of IBD-related colon carcinogenesis.

Methods

Female CD-1 (ICR) mice were given a single intraperitoneal administration of AOM (10 mg/kg body weight) and followed by one-week oral exposure of 2% (w/v) DSS in drinking water, and then maintained on the basal diets mixed with or without nimesulide (0.04%, w/w), troglitazone (0.05%, w/w), and bezafibrate (0.05%, w/w) for 14 weeks. The inhibitory effects of dietary administration of these compounds were determined by histopathological and immunohistochemical analyses.

Results

Feeding with nimesulide and troglitazone significantly inhibited both the incidence and multiplicity of colonic adenocarcinoma induced by AOM/DSS in mice. Bezafibrate feeding significantly reduced the incidence of colonic adenocarcinoma, but did not significantly lower the multiplicity. Feeding with nimesulide and troglitazone decreased the proliferating cell nuclear antigen (PCNA)-labeling index and expression of β-catenin, COX-2, inducible nitric oxide synthase (iNOS) and nitrotyrosine. The treatments increased the apoptosis index in the colonic adenocarcinoma. Feeding with bezafibrate also affected these parameters except for β-catenin expression in the colonic malignancy.

Conclusion

Dietary administration of nimesulide, troglitazone and bezafibrate effectively suppressed the development of colonic epithelial malignancy induced by AOM/DSS in female ICR mice. The results suggest that COX-2 inhibitor and PPAR ligands could serve as an effective agent against colitis-related colon cancer development.

Cyclooxygenase-2 parallels invasive depth and increased MVD in transitional cell carcinoma

To investigate the relationship between the expression of cyclooxygenase-2 (COX-2), and invasive depth and angiogenesis in human transitional cell carcinoma (TCC), the expression of COX-2 and von Willebrand factor (vWF) was detected in paraffin-embedded transitional cell carcinoma specimens from 50 patients with histologically confirmed bladder transitional cell carcinoma. Microvessels were counted and microvessel density (MVD) was calculated. The correlation between COX-2 and invasive depth, MVD and invasive depth, COX-2 and MVD were analyzed. COX-2 expression was significantly related to the invasive depth of tumors; it solely expressed in invasive TCC. The ratio of COX-2 positively stained samples in each stage correlated to the invasive stages; so did the proportion of COX-2 (+) cells in whole tumor cells. Also, MVD increased with the invasive stages of tumors and positively correlated to the invasive depth. The COX-2-positive TCC samples were highly vascular, their microvessel density was significantly higher than that of the COX-2-negative TCC samples. There was a positive correlation between MVD and COX-2 (+) cells proportion. Our findings suggested that COX-2 was positively correlated with the invasive depth and involved in the process of angiogenesis in human transitional cell carcinoma.

Xanthorrhizol, a natural sesquiterpenoid from Curcuma xanthorrhiza, has an anti-metastatic potential in experimental mouse lung metastasis model

Xanthorrhizol is a sesquiterpenoid compound isolated from the rhizome of Curcuma xanthorrhiza. In this study, the anti-metastatic activity of xanthorrhizol was evaluated by using an in vivo mouse lung metastasis model and a tumor mass formation assay. Interestingly, xanthorrhizol dramatically inhibited the formation of tumor nodules in the lung tissue and the intra-abdominal tumor mass formation. Next, to examine the mechanism of the anti-metastatic action of xanthorrhizol in the mouse lung metastasis, expression patterns of the several intracellular signaling molecules were evaluated using the lung tissues with tumor nodules. Higher expression levels of cyclooxygenase-2 (COX-2), matrix metalloproteinase-9 (MMP-9), and phosphorylated extracellular signal-regulated kinase (ERK) were observed in the metastatic group compared with control, but these were attenuated by the treatment of xanthorrhizol. In conclusion, xanthorrhizol exerts anti-metastatic activity in vivo and this effect could be highly linked to the metastasis-related multiplex signal pathway including ERK, COX-2, and MMP-9.

Sulindac corrects defective apoptosis and suppresses azoxymethane-induced colonic oncogenesis inp53 knockout mice

The acute apoptotic response to genotoxic carcinogens (AARGC) might be important for controlling the subsequent colonic mutational load and progression through oncogenesis. We have found previously that AARGC is p53-dependent with a gene-dosage effect, and that decreased AARGC in p53(+/-) and p53(-/-) mice is associated with increased susceptibility to carcinogen-induced oncogenesis. We tested the ability of sulindac to reverse these defects. The effect of sulindac on azoxymethane (AOM)-induced apoptosis was measured in colonic epithelium in wild-type, p53(+/-) and p53(-/-) mice, 8 hr after a single AOM injection. Sulindac supplementation (0.5 +/- 0.1 mg/day) restored defective AARGC in p53(+/-) but not in p53(-/-) mice. For effect on colon tumor development, sulindac treatment was started at age 4 weeks in wild-type, p53(+/-) and p53(-/-) mice; three weekly AOM injections were commenced at 6 weeks of age to induce tumors. Sulindac reduced significantly tumor incidence and multiplicity in wild-type mice (17% and 0.3 tumors/mouse compared to 36% and 0.8 respectively without drug), in p53(+/-)mice (38% and 0.8 compared to 64% and 1.63) and in p53(-/-) mice (63% and 1.0 compared to 90% and 1.74). Although loss of p53 function impairs the apoptotic response to AOM-induced DNA damage, sulindac is capable of partly restoring this defect. As sulindac also reverses the increased risk of oncogenesis due to p53 dysfunction, its enhancement of the apoptotic response to initiating mutations might act to reduce mutational load driving oncogenesis. Sulindac is an effective chemopreventive agent in the presence of p53 dysfunction.

Ibuprofen Inhibits Survival of Bladder Cancer Cells by Induced Expression of the p75NTR Tumor Suppressor Protein

Nonsteroidal anti-inflammatory drugs (NSAIDs) are used to reduce inflammation and as analgesics by inhibition of cyclooxygenase-2. At higher concentrations, some NSAIDs inhibit proliferation and induce apoptosis of cancer cells. Although several molecular mechanisms have been postulated to explain the anticancer effects of NSAIDs, they do not involve merely the inhibition of cyclooxygenase-2, and a more proximate initiator molecule may be regulated by NSAIDs to inhibit growth. The p75 neurotrophin receptor (p75NTR) is a proximate cell membrane receptor glycoprotein that has been identified as a tumor and metastasis suppressor. We observed that NSAID treatment of cell lines from bladder and other organs induced expression of the p75NTR protein. Of the different types of NSAIDs examined, ibuprofen was more efficacious than aspirin and acetaminophen and comparable with (R)-flurbiprofen and indomethacin in induction of p75NTR protein expression. This rank order NSAID induction of the p75NTR protein correlated with the ability of these NSAIDs to reduce cancer cell survival. To examine a mechanistic relationship between ibuprofen induction of p75NTR protein and inhibition of survival, bladder cancer cells were transfected with ponasterone A-inducible vectors that expressed a death domain-deleted (DeltaDD) or intracellular domain-deleted (DeltaICD) p75NTR product that acts as a dominant negative antagonist of the intact p75NTR protein. Expression of DeltaDD and DeltaICD rescued cells from ibuprofen inhibition of growth. These observations suggest that p75NTR is an important upstream modulator of the anticancer effects of NSAIDs and that ibuprofen induction of the p75NTR protein establishes an alternate mechanism by which ibuprofen may exert an anticancer effect.

Glutathione-S-transferase P1-1 protects aberrant crypt foci from apoptosis induced by deoxycholic acid

BACKGROUND & AIMS

Aberrant crypt foci, precursors of colonic adenoma, are frequently positive for glutathione-S-transferase P1-1. Because deoxycholic acid is an apoptosis-inducing xenobiotic in the colon, we examined the possibility that aberrant crypt foci, through the cytoprotecting function of glutathione-S-transferase P1-1, resist deoxycholic acid-induced apoptosis, thereby surviving to become adenomas and subsequently cancer.

METHODS

Glutathione-S-transferase P1-1 or cyclooxygenase-2 expression and the percentage of apoptotic cells in aberrant crypt foci were examined by immunohistochemistry and by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling, respectively. Glutathione-S-transferase P1-1 was transfected into colon cancer cells (M7609) and human lung fibroblasts, and deoxycholic acid-induced apoptosis was evaluated by a dye-uptake assay and flow cytometry. Binding of deoxycholic acid to glutathione-S-transferase P1-1 was analyzed by circular dichroism and immunoprecipitation. Caspase activities were determined by colorimetric protease assay, and sulindac binding to glutathione-S-transferase P1-1 was determined by inhibition assay of glutathione-S-transferase P1-1 activity.

RESULTS

Aberrant crypt foci showed positive immunostaining for glutathione-S-transferase P1-1 but negative staining for cyclooxygenase-2. The percentage of apoptotic cells in aberrant crypt foci was significantly lower than in healthy epithelium, and the difference became more apparent with deoxycholic acid treatment. The impaired sensitivity of aberrant crypt foci to deoxycholic acid was restored by the glutathione-S-transferase P1-1-specific inhibitor gamma-glutamyl-S-(benzyl)cysteinyl-R-phenylglycine diethylester. By transfection of glutathione-S-transferase P1-1, M7609 cells became more resistant to deoxycholic acid-induced apoptosis than mock transfectants. Direct binding of glutathione-S-transferase P1-1 to deoxycholic acid was proven by circular dichroism and by immunoprecipitation. The aberrant crypt foci in adenoma patients treated with sulindac, which was shown to bind to glutathione-S-transferase P1-1, underwent apoptosis in 4 days and mostly regressed in 2-3 months.

CONCLUSIONS

Glutathione-S-transferase P1-1 protects aberrant crypt foci from deoxycholic acid-induced apoptosis and may play a pivotal role in early colon carcinogenesis.

Antiproliferative crude soy saponin extract modulates the expression of IkappaBalpha, protein kinase C, and cyclooxygenase-2 in human colon cancer cells

Frequent consumption of soy and soy-based products is associated with reduced cancer incidence particularly for breast, colon, and prostate cancer. In this study, we examined the effect of crude soy saponin extract on PMA (phorbol 12-myristate 13-acetate)-induced inflammatory responses. Human adenocarcinoma cells (HT-29) were treated with various concentrations of saponin extract for 72 h. Cell growth was measured at 24, 48 and 72 h of incubation, and the PMA-induced expressions of cyclooxygenase-2 (COX-2), protein kinase C (PKC), and IkappaBalpha were determined. The results indicate that crude saponin extract decreased cell growth in a dose- and time-dependent manner. Crude soy saponin extract suppressed the degradation of IkappaBalpha in PMA-stimulated cells, while COX-2 and PKC expressions were significantly down-regulated. These findings support the hypothesis that the soy saponins reduce the risk of colon tumorigenesis possibly by suppressing inflammatory responses.

Effects of low dose aspirin (81 mg) on proliferating cell nuclear antigen and Amaranthus caudatus labeling in normal-risk and high-risk human subjects for colorectal cancer

Epidemiological, experimental, and clinical observations provide support for a colorectal cancer chemopreventive role for aspirin. We have evaluated the effects of aspirin on proliferation biomarkers in normal-risk and high-risk human subjects for colorectal cancer. Colorectal biopsies were obtained at baseline and at 24h after 28 daily doses of 81 mg of aspirin from 13 high-risk and 15 normal-risk subjects for colorectal cancer. We evaluated aspirin's effects on proliferating cell nuclear antigen (PCNA) immunohistochemistry and epithelial mucin histochemistry using the lectin, Amaranthus caudatus agglutinin (ACA) in crypt sections from rectal biopsies. The baseline whole crypt PCNA LIs differed significantly between normal-risk and high-risk subjects. PCNA LIs are not affected by 28 days of aspirin at 81 mg daily. ACA LIs are decreased by 28 days of aspirin at 81 mg daily in both normal-risk and high-risk subjects. Aspirin's effects on ACA LIs may have mechanistic and biological implications that deserve further attention. PCNA and ACA LIs are not useful as proliferation biomarkers for aspirin's chemopreventive activity in morphologically normal human colorectal mucosa.

Cyclooxygenase-2 inhibitor (SC-236) suppresses activator protein-1 through c-Jun NH2-terminal kinase

BACKGROUND AND AIMS

Aspirin exerts antitumor effect partly through blocking tumor promoter-induced activator protein-1 (AP-1) activation. The aim of this study is to determine how specific COX-2 inhibitor SC-236 mediates antitumor effect by modulation of AP-1-signaling pathway.

METHODS

AP-1 transcriptional activity and DNA-binding activity were detected by luciferase reporter assay and gel shift assay, separately. Mitogen-activated protein kinase (MAPK) activation was determined by Western blot and in vitro kinase assay. Antisense oligonucleotide against c-Jun-N-terminal kinase (JNK) was used to suppress JNK expression.

RESULTS

We showed that SC-236 inhibited 12-O-tetradecanoylphorbol-13-acetate (PMA)-induced cell transformation in a dose-dependent manner in JB6 cells. At a dose range (12.5-50 micromol/L) that inhibited cell transformation, SC-236 also inhibited anchorage-independent cell growth and AP-1-activation in 3 gastric cancer cells, independent of COX-prostaglandin synthesis. SC-236 down-regulated c-Jun-NH2-terminal kinase phosphorylation and activity. Suppression of JNK activity reversed the inhibitory effect on AP-1 activity by SC-236 and suppressed gastric cancer cell growth, indicating that the inhibitory effect of SC-236 on AP-1 activation and cell growth was through interaction with JNK.

CONCLUSIONS

The inhibitory effect on JNK-c-Jun/AP-1 activation contributes to the antitumor effect of COX-2-specific inhibitor, and inhibition of JNK activation may have a therapeutic benefit against gastric cancer.

Role of cyclooxygenase-2 in the angiogenesis of colorectal cancer

BACKGROUND

Cyclooxygenase (COX) is the rate-limiting enzyme in the synthesis of prostaglandins. It exists in two isoforms: COX-1 which is constitutively expressed and COX-2 which is an inducible form activated by a variety of cytokines during inflammation.

DISCUSSION

Interest in this enzyme arose in the early 1990s when, following epidemiological studies, aspirin (which is a COX inhibitor) was found to reduce the risk of colorectal cancer. Since then various studies to decipher the mechanisms by which COX reduces the development of colorectal cancer have been undertaken. One of the mechanisms being studied is its role in the angiogenesis of colorectal cancer. Angiogenesis of its own has been well established as a key factor in the development of tumours. Agents that specifically inhibit COX-2 are now in clinical development and have been licensed to be used in patients with familial adenomatosis polyposis.

CONCLUSION

What needs to be determined is whether the antiangiogenic effects of COX-2 inhibitors can be used in the prevention and/or treatment of colorectal cancer and its metastases.

Gastrin and EGF synergistically induce cyclooxygenase-2 expression in Swiss 3T3 fibroblasts that express the CCK2 receptor

Over-expression of cyclooxygenase-2 (COX-2) has been demonstrated to be tumorigenic in transgenic mice. Chronic treatment with NSAIDs is chemoprotective for colorectal cancer. Gastrin is a growth factor for gastric mucosa and has been shown to promote proliferation of colorectal cells. Recent studies suggest that COX-2 expression levels could mediate the growth effects of gastrin. Here, we report that gastrin increased PGE2 secretion in Swiss 3T3 cells expressing the CCK2 receptor. Gastrin dose dependently induced COX-2 protein levels in a time dependent manner. COX-2 mRNA levels were rapidly induced by a dose dependent increase in gastrin. Prior treatment of the cells with the CCK2 receptor specific antagonist, L365,260, inhibited gastrin-induced COX-2 protein and mRNA expression. Pretreatment with L364,714, the CCK1 receptor specific antagonist did not block COX-2 induction by gastrin. Inhibition of de novo protein synthesis by cycloheximide did not block COX-2 mRNA induction by gastrin. Also, gastrin-dependent COX-2 expression did not require PKC activity, activation of ERK, or transactivation of EGFR. However, co-stimulation with EGF and gastrin synergistically induced COX-2 protein and mRNA expression and PGE2 secretion. Measurements of COX-2 mRNA stability and COX-2 gene transcription reveal that EGF significantly increased the half-life of COX-2 mRNA with only a slight increase in the COX-2 transcription rate. Conversely, gastrin significantly increased COX-2 gene transcription rates but did not enhance COX-2 mRNA stability.

Activity of the non-steroidal anti-inflammatory drug indomethacin against colorectal cancer

A substantial body of evidence from rodent colon carcinogenesis models, in vitro experiments with human colorectal cancer cells and limited clinical observations in humans suggest that the non-steroidal anti-inflammatory drug indomethacin has anti-colorectal cancer activity. However, although many mechanisms of the anti-neoplastic activity of indomethacin have been suggested, e.g., cyclooxygenase inhibition and peroxisome proliferator-activated receptor gamma activation, the precise relevance of the majority of in vitro pharmacological observations to the in vivo anti-neoplastic activity of indomethacin remains unclear. Herein, we review the existing literature describing the chemopreventative and chemotherapeutic efficacy of indomethacin against colorectal cancer, and draw together the disparate literature describing potential mechanisms of action of indomethacin in human colorectal cancer cells in vitro. Although indomethacin itself has significant adverse effects, including serious upper gastrointestinal toxicity, the development of novel derivatives that may have an improved safety profile means that further investigation of the anti-colorectal cancer activity of indomethacin is warranted.

Non-steroidal anti-inflammatory drugs inhibit nitric oxide-induced apoptosis and dedifferentiation of articular chondrocytes independent of cyclooxygenase activity

Nitric oxide (NO) causes apoptosis and dedifferentiation of articular chondrocytes by the modulation of extracellular signal-regulated kinase (ERK), p38 kinase, and protein kinase C (PKC) alpha and -zeta. In this study, we investigated the effects and mechanisms of non-steroidal anti-inflammatory drugs (NSAIDs), such as indomethacin, ketoprofen, ibuprofen, sulindac sulfide, and flurbiprofen, in NO-induced apoptosis and dedifferentiation of articular chondrocytes. We found that all of the examined NSAIDs inhibited apoptosis and dedifferentiation. NO production in chondrocytes caused activation of ERK-1/2 and p38 kinase, which oppositely regulate apoptosis and dedifferentiation. NO production also caused inhibition of PKCalpha and -zeta independent of and dependent on, respectively, p38 kinase, which is required for apoptosis and dedifferentiation. Among the signaling molecules modulated by NO, NSAIDs blocked NO-induced activation of p38 kinase, potentiated ERK activation, and blocked inhibition of PKCalpha and -zeta. NSAIDs also inhibited some of the apoptotic signaling that is downstream of p38 kinase and PKC, such as NFkappaB activation, p53 accumulation, and caspase-3 activation. The inhibitory effects of NSAIDs on apoptosis and dedifferentiation were independent of the inhibition of cyclooxygenase (COX)-2 and prostaglandin E(2) (PGE(2)) production, as evidenced by the observation that specific inhibition of COX-2 activity and PGE(2) production or exogenous PGE(2) did not affect NO-induced apoptosis and dedifferentiation. Taken together, our results indicate that NSAIDs block NO-induced apoptosis and dedifferentiation of articular chondrocytes by the modulation of ERK, p38 kinase, and PKCalpha and -zeta in a manner independent of their ability to inhibit COX-2 and PGE(2) production.

Cyclooxygenase-2 increased the angiogenic and metastatic potential of tumor cells

It seems certain that COX-2 is related to tumor and some data suggested that COX-2 might have relation to tumor malignance and angiogenesis. In order to elucidate the relationship between COX-2 and tumor invasive and angiogenic ability, we transfected human transitional cell carcinoma (TCC) cell line, EJ, permanently with a COX-2 expression vector or the mock vector. The EJ-COX(2) cells, which overexpressed COX-2, acquired increased invasiveness and angiogenic ability by activation of VEGF, uPA, and MMP-2. Increased invasiveness and angiogenic ability were reversed by treatment with either selective COX-2 inhibitor, NS-398, or dual COX inhibitor, indomethacin. These results demonstrate that overexpression of COX-2 can lead to phenotypic changes that alter the metastatic and angiogenic potential of TCC cancer cells.

The combination of 1alpha,25(OH2)-vitamin D3, calcium and acetylsalicylic acid affects azoxymethane-induced aberrant crypt foci and colorectal tumours in rats

Effects of 1alpha,25(OH)(2)-vitamin D(3) and acetylsalicylic acid at various dietary levels of calcium (CaCO(3)) on development of aberrant crypt foci (ACF) and tumours in colon were examined in groups of 16 male F344 rats initiated with azoxymethane and observed for 16 weeks. Calcium was the most potent modulator of ACF development. The total number of ACF increased with low calcium and decreased with high calcium. The number of large ACF decreased with any addition of calcium, acetylsalicylic acid and 1alpha,25(OH)(2)-vitamin D(3). High levels of calcium alone or in combination with 1alpha,25(OH)(2)-vitamin D(3) increased the incidence of tumour-bearing animals. 1alpha,25(OH)(2)-vitamin D(3) and acetylsalicylic acid at 5,000 ppm calcium increased the incidence as well.

Novel target for induction of apoptosis by cyclo-oxygenase-2 inhibitor SC-236 through a protein kinase C-beta(1)-dependent pathway

Nonsteroidal anti-inflammatory drugs (NSAIDs) reduce the risk of gastrointestinal cancers. Recently, a similar protective effect has been demonstrated by the specific cyclo-oxygenase-2 (COX-2) inhibitors. However, the exact mechanism that accounts for the anti-proliferative effect of specific COX-2 inhibitors is still not fully understood, and it is still controversial whether these protective effects are predominantly mediated through the inhibition of COX-2 activity and prostaglandin synthesis. Identification of molecular targets regulated by COX-2 inhibitors could lead to a better understanding of their pro-apoptotic and anti-neoplastic activities. In the present study, we investigated the effect and the possible molecular target of a COX-2-specific inhibitor SC-236 on gastric cancer. We showed that SC-236 induced apoptosis in gastric cancer cells. However, this effect was not dependent on COX-2 inhibition. SC-236 down-regulated the protein expression and kinase activity of PKC-beta(1), increased the expression of PKCdelta and PKCeta, but did not alter the expression of other PKC isoforms in AGS cells. Moreover, exogenous prostaglandins or PGE(2) receptor antagonists could not reverse the inhibition effect on PKCbeta(1) by SC-236, which suggested that this effect occurred through a mechanism independent of cyclo-oxygenase activity and prostaglandin synthesis. Overexpression of PKCbeta(1) attenuated the apoptotic response of AGS cells to SC-236 and was associated with overexpression of p21(waf1/cip1). Inhibition of PKCbeta(1)-mediated overexpression of p21(waf1/cip1) partially reduced the anti-apoptotic effect of PKCbeta(1). The down-regulation of PKCbeta(1) provides an explanation for COX-independent apoptotic effects of specific COX-2 inhibitor in cultured gastric cancer cells. We also suggest that PKCbeta(1) act as survival mediator in gastric cancer, and its down-regulation by COX-2 inhibitor SC-236 may provide new target for future treatment of gastric cancer.

COX-2 selective inhibition reverses the trophic properties of gastrin in colorectal cancer

Gastrin is a gastrointestinal peptide that possesses potent trophic properties on both normal and neoplastic cells of gastrointestinal origin. Previous studies have indicated that chronic hypergastrinaemia increases the risk of colorectal cancer and cancer growth and that interruption of the effects of gastrin could be a potential target in the treatment of colorectal cancer. Here we demonstrate that gastrin leads to a dose-dependent increase in colon cancer cell proliferation and tumour growth in vitro and in vivo, and that this increment is progressively reversed by pretreatment with the cyclo-oxygenase-2 inhibitor NS-398. Gastrin was able to induce cyclo-oxygenase-2 protein expression, as well as the synthesis of prostaglandin E2, the major product of cyclo-oxygenase. Moreover, gastrin leads to approximately a two-fold induction of cyclo-oxygenase-2 promoter activity in transiently transfected cells. The results of these studies demonstrate that cyclo-oxygenase-2 appears to represent one of the downstream targets of gastrin and that selective cyclo-oxygenase-2 inhibition is capable of reversing the trophic properties of gastrin and presumably might prevent the growth of colorectal cancer induced by hypergastrinaemia.

The MEK/ERK pathway mediates COX-2-selective NSAID-induced apoptosis and induced COX-2 protein expression in colorectal carcinoma cells

Nonsteroidal antiinflammatory drugs (NSAIDs) can prevent colorectal tumorigenesis in humans and in rodents. In vitro and in vivo studies indicate that one of their principal antineoplastic avenues is the induction of apoptosis. We have shown previously that NS-398, which selectively inhibits cyclooxygenase-2 (COX-2) over cyclooxygenase-1, induces apoptosis of colorectal tumour cells and elevates COX-2 protein expression. Here, we have determined that the extracellular signal-regulated kinase kinase (MEK)/extracellular signal-regulated kinase (ERK) pathway mediates these effects of NS-398. Treatment of HT29 colorectal carcinoma cells with 75 microM NS-398 caused activation of ERK-1/-2 but not of the p38 and c-Jun N-terminal kinase (JNK) mitogen-activated protein kinases. This was apparent at 24 hr and maintained at 72 hr. U0126, a specific inhibitor of the ERK-activating kinases MEK-1/-2, prevented the activation of ERK induced by NS-398 and blocked the increase in COX-2 protein expression seen when HT29 cells were treated with NS-398 alone. The activation of ERK by NS-398 preceded and accompanied a decrease in attached cell yield and an increase in apoptosis. U0126 dose-dependently protected HT29 cells from these antiproliferative effects of NS-398, indicating an antiproliferative role for sustained ERK-1/-2 activation in response to this NSAID. These results point to a key role for the MEK/ERK signalling pathway in mediating the effects of a COX-2-selective NSAID on colorectal carcinoma cells.

Effect of Helicobacter pylori-induced cyclooxygenase-2 on gastric epithelial cell kinetics: implication for gastric carcinogenesis

BACKGROUND

Cyclooxygenase (COX)-2 induced by Helicobacter pylori is thought to enhance gastric carcinogenesis by affecting the maintenance of epithelial homeostasis.

MATERIALS AND METHODS

Gastric biopsies from 160 subjects, 97 with nonulcer dyspepsia (47 H. pylori negative, 50 H. pylori positive) and 63 with gastric cancer were examined immunohistochemically for COX-2 expression, cell proliferation and apoptotic indices.

RESULTS

COX-2 expression in corpus was significantly higher in H. pylori positive than in negative non-ulcer dyspepsia (NUD) (p <.05). Regardless of site, gastric cancer subjects had higher COX-2 expression in both antrum and corpus compared with H. pylori negative and positive NUD (p <.005). Proliferation was higher in cancer and H. pylori positive than in negative NUD (p <.0001). Moreover, cancer had enhanced proliferation than H. pylori positive NUD in corpus greater (p =.0454) and antrum lesser (p =.0215) curvatures. Apoptosis was higher in H. pylori positive than in negative NUD (p <.05). However, both had a higher index than the cancer subjects (p <.0001). Apoptosis : proliferation ratio was higher in corpus of H. pylori negative than in positive NUD in greater (p =.0122) and lesser (p =.0009) curvatures. However, both had a higher A:P ratio than cancer cases (p =.0001). A negative correlation between COX-2 expression and A:P ratio was found in corpus greater (r = -.176, p =.0437) and lesser (r = -.188, p =.0312) curvatures.

CONCLUSION

The expression of COX-2 is associated with disruption in gastric epithelial kinetics and hence may play a role in gastric carcinogenesis.

Aberrant crypt foci in colorectal carcinogenesis. Cell and crypt dynamics

Aberrant crypt foci (ACF) have been identified on the colonic mucosal surface of rodents treated with colon carcinogens and of humans after methylene-blue staining and observation under a light microscope. Several lines of evidence strongly suggest that ACF with certain morphological, histological, cell kinetics, and genetic features are precursor lesions of colon cancer both in rodents and in humans. Thus, ACF represent the earliest step in colorectal carcinogenesis. This paper has the main purpose of reviewing the evidence supporting this view, with particular emphasis on cell and crypt dynamics in ACF. ACF have been used as intermediate biomarkers of cancer development in animal studies aimed at the identification of colon carcinogens and chemopreventive agents. Recently, evidence has also shown that ACF can be effectively employed in chemopreventive studies also in humans.

Cyclooxygenase-independent actions of cyclooxygenase inhibitors

Several studies have demonstrated unequivocally that certain nonsteroidal anti-inflammatory drugs (NSAIDs) such as sodium salicylate, sulindac, ibuprofen, and flurbiprofen cause anti-inflammatory and antiproliferative effects independent of cyclooxygenase activity and prostaglandin synthesis inhibition. These effects are mediated through inhibition of certain transcription factors such as NF-kappaB and AP-1. The respective NSAIDs might interfere directly with the transcription factors, but their effects are probably mediated predominantly through alterations of the activity of cellular kinases such as IKKbeta, Erk, p38 MAPK, or Cdks. These effects apparently are not shared by all NSAIDs, since indomethacin failed to inhibit NF-kappaB and AP-1 activation as well as Erk and Cdk activity. In contrast, indomethacin was able to activate PPARgamma, which was not affected by sodium salicylate or aspirin. The differences in cyclooxygenase-independent mechanisms may have consequences for the specific use of these drugs in individual patients because additional effects may either enhance the efficacy or reduce the toxicity of the respective compounds.

Apoptosis: implications for inflammatory bowel disease

Cells of the intestinal mucosa live in a harsh environment and therefore rely heavily on the highly regulated process of cell death, apoptosis, to maintain tissue integrity. Imbalance in the intracellular events that modulate apoptosis may contribute to the pathogenesis of inflammatory bowel disease.