Cyclooxygenase-2 expression is increased in early intestinal-type gastric cancer and gastric mucosa with intestinal metaplasia

Characteristics of gastric precancerous conditions and Helicobacter pylori infection among dyspeptic patients in north-eastern Iran: is endoscopic biopsy and histopathological assessment necessary?

Background

Early detection and appropriate treatment of precancerous, mucosal changes could significantly decrease the prevalence of life-threatening gastric cancer. Biopsy of the normal-appearing mucosa to detect Helicobacter pylori and these conditions is not routinely obtained. This study assesses the prevalence and characteristics of H. pylori infection and precancerous conditions in a group of patients suffering from chronic dyspepsia who were subjected to gastric endoscopy and biopsy mapping.

Methods

This cross-sectional study included dyspeptic patients, not previously treated for H. pylori, undergoing esophagogastroduodenoscopy (EGD) with their gastric endoscopic biopsies obtained for examination for evidence of H. pylori infection and precancerous conditions. Demographic and clinical data on the gender, smoking, opium addiction, alcohol consumption, medication with aspirin, corticosteroids and non-steroidal anti-inflammatory drugs (NSAIDs) and family history of cancer were collected by interviewing the patients and evaluating their health records. The cohort examined consisted of 585 patients with a mean (SD) age of 48.0 (14.46) years, 397 (67.9%) of whom were women.

Results

H. pylori infection was identified in 469 patients (80.2%) with the highest prevalence (84.2%) in those aged 40–60 years. Opium addiction correlated with a higher a H. pylori infection rate, while alcohol consumption was associated with a lower rate by Odds Ratio 1.98 (95% CI 1.11–3.52) and 0.49 (95% CI 0.26–0.92), respectively. The prevalence of intestinal metaplasia, gastric atrophy and gastric dysplasia was 15.2, 12.6 and 7.9%, respectively. Increased age, positive H. pylori infection, endoscopic abnormal findings and opium addiction showed a statistically significant association with all precancerous conditions, while NSAID consumption was negatively associated with precancerous conditions. For 121 patients (20.7% of all), the EGD examination revealed normal gastric mucosa, however, for more than half (68/121, 56.2%) of these patients, the histological evaluation showed H. pylori infection, and also signs of atrophic mucosa, intestinal metaplasia and dysplasia in 1.7, 4.1 and 1.7%, respectively.

Conclusion

EGD with gastric biopsy mapping should be performed even in the presence of normal-appearing mucosa, especially in dyspeptic patients older than 40 years with opium addiction in north-eastern Iran. Owing to the high prevalence of precancerous conditions and H. pylori infection among patients with dyspepsia in parts of Iran, large-scale national screening in this country should be beneficial.

Gene expression patterns of COX-1, COX-2 and iNOS in H. Pylori infected histopathological conditions

BACKGROUND

Research indicates that Helicobacter pylori can inflict severe histological damage through the modulation of host-related genes. The current study investigated the effect of H. pylori genotypes in the outcome of disease, and the expression of anti-apoptotic related genes, COX-1, COX-2, and iNOS genes in benign, pre-malignant, and malignant lesions of gastric carcinogenesis.

MATERIALS AND METHODS

Tissue samples from H. pylori positive patients were graded based on the genotype of the infected H. pylori strain. Expression of COX-1, COX-2 and iNOS was assessed using a combination of real-time PCR and immunohistochemistry.

RESULTS

Gene expression studies confirmed that COX-2 and iNOS expression was highly and selectively induced in epithelium with premalignant changes such as atrophic conditions, metaplasia and dysplasia, suggesting an important role of these genes in the sequence to gastric carcinoma of the intestinal type. Furthermore, the expression of COX-2 and iNOS was also dependent on the genotype of H. pylori and subjects with genotype-1 exhibited significantly higher expressions of COX-2 and iNOS compared to other genotypes. Comparison of the expression levels among infected and uninfected individuals demonstrated significant difference in the expression pattern of COX-2 gene whereas iNOS expression was found only in subjects infected H. pylori (p < 0.001). Immunohistochemical staining showed 1.5619 folds higher propensity of COX-2 and 3.2941 folds higher intensity of iNOS expression in subjects infected with H. pylori genotype 1.

CONCLUSION

The up-regulation of COX-2 and iNOS was associated with the genotype of the H. pylori strain and the presence of certain genotype may greatly affect early events during carcinogenesis.

Resveratrol Treatment Inhibits Proliferation of and Induces Apoptosis in Human Colon Cancer Cells

Background

Resveratrol, a natural isolate from plant sources, has a long and important history in traditional Chinese medicine. In the present study we investigated the effect of resveratrol on human colon cancer cell lines.

Material/Methods

We used the Cell Counting kit-8 (CCK-8) for determination of colon cancer cell viability. Apoptosis induction was analyzed using the DeadEnd™ Colorimetric TUNEL System (Promega, Madison, WI, USA). The siRNA Transfection Reagent kit (Santa Cruz Biotechnology, Inc.) was used for the administration of COX-2 silencer RNA (siRNA) into the colon cancer cells. Primer Express^® software for Real-Time PCR ver. 3.0 (Applied Biosystems, Foster City, CA, USA) was used to prepare the primers for RT-PCR.

Results

The results revealed that exposure of colon cancer cells to resveratrol inhibited cell viability. Resveratrol exhibited a significant inhibitory effect on cell viability at 30 μM concentration after 48 h of exposure. We observed that 30-μM doses of resveratrol for 72 h led to 18, 29, and 34% reduction in the viability of HCA-17, SW480, and HT29 cells, respectively. It also significantly induced apoptosis in both of the tested carcinoma cell lines. The population of apoptotic cells in HCA-17 and SW480 cell lines after 48 h of resveratrol treatment was 59.8±4 and 67.2±4%, respectively, compared to 2.3±1% in the control cells. The colon cancer cells exposed to resveratrol showed significantly lower cyclooxygenase-2 and prostaglandin receptor expression. Treatment of colon cancer cells with the inhibitor of cyclooxygenase-2, indomethacin, and administration of silencer RNA for cyclooxygenase-2 also produced similar results.

Conclusions

These findings suggest that resveratrol treatment can be a promising strategy for the treatment of colon cancer.

Helicobacter pylori, cyclooxygenase-2 and evolution of gastric lesions: results from an intervention trial in China

To investigate the role of cyclooxygenase (COX)-2/prostaglandin E2 (PGE2) in the process of Helicobacter pylori-induced gastric carcinogenesis, a prospective study based on an intervention trial was conducted in Linqu County, China. A total of 1401 subjects with histopathologic diagnosis were investigated at baseline, among those, 919 completed subsequent interventions (anti-H.pylori and/or celecoxib treatment). Expressions of COX-2 and Ki-67 were assessed by immunohistochemistry, and PGE2 levels were measured by enzyme immunoassay before and after interventions, respectively. We found a grade-response relationship between COX-2 expression level and risk of advanced gastric lesions at baseline. Stratified analysis indicated an additive interaction between COX-2 expression and H.pylori infection on the elevated risk of advanced gastric lesions. The odds ratios (ORs) for both factors combined were 9.31 [95% confidence interval (CI): 4.13-20.95] for chronic atrophic gastritis, 16.26 (95% CI: 7.29-36.24) for intestinal metaplasia and 21.13 (95% CI: 7.87-56.75) for dysplasia, respectively. After interventions, COX-2 expression and Ki-67 labeling index (LI) were decreased in anti-H.pylori group (OR: 1.65, 95% CI: 1.36-1.99 for COX-2; OR: 1.78, 95% CI: 1.49-2.12 for Ki-67) or anti-H.pylori followed by celecoxib group (OR: 1.41, 95% CI: 1.17-1.70 for COX-2; OR: 1.63, 95% CI: 1.37-1.94 for Ki-67). PGE2 levels were decreased in all treatment groups. Furthermore, the regression of gastric lesions was associated with the decrease of COX-2 expression or Ki-67 LI after interventions. Our findings indicate that H.pylori-induced COX-2/PGE2 pathways play an important role on the progression of precancerous gastric lesions in a Chinese population.

Inflammation and cancer

There is evidence supporting the hypothesis that inflammation participates in providing conditions that lead to cancer. An unresolved inflammation due to any failure in the precise control of the immune response can continue to perturb the cellular microenvironment, thereby leading to alterations in cancer-related genes and posttranslational modification in crucial cellular proteins involved in the cell cycle, DNA repair and apoptosis. In addition, there are data indicating that inflammatory cells and immunomodulatory mediators present in the tumor microenvironment influence tumor progression and metastasis. Historically, tumor-infiltrating leukocytes have been considered to be manifestations of an intrinsic defence mechanism against developing tumors. However, increasing evidence indicates that leukocyte infiltration can promote tumor phenotypes, such as angiogenesis, growth and invasion. This may be due to inflammatory cells that probably can influence cancer promotion by secreting cytokines, growth factors, chemokines and proteases, which stimulate proliferation and invasiveness of cancer cells. Consequently, events and molecules implicated in this cross talk between the tumor microenvironment and inflammatory process may emerge as attractive targets in anticancer therapeutic interventions with significant clinical impact.

Immunoexpression of cyclooxygenase-2 in primary gastric carcinomas and lymph node metastases

AIM

To evaluate immunoexpression of cyclooxygenase-2 (COX-2) in primary gastric carcinomas and respective lymph node metastases.

METHODS

Immunohistochemistry to analyze COX-2 expression was performed on tissue microarray slices obtained from 36 specimens of gastrectomy and satellite lymph nodes from patients with gastric carcinoma.

RESULTS

Immunostaining was seen in most cases, and COX-2 expression was higher in lymph node metastases than in corresponding primary gastric tumors of intestinal, diffuse and mixed carcinomas, with a statistically significant difference in the diffuse histotype (P = 0.0108).

CONCLUSION

COX-2 immunoexpression occurs frequently in primary gastric carcinomas, but higher expression of this enzyme is observed in lymph node metastases of the diffuse histotype.

Preferential up-regulation of heparanase and cyclooxygenase-2 in carcinogenesis of Barrett's oesophagus and intestinal-type gastric carcinoma

AIMS

Metaplastic changes secondary to chronic inflammation at the gastro-oesophageal junction and at the pyloric antrum are recognized as the premalignant conditions of Barrett's oesophageal adenocarcinoma and intestinal-type gastric carcinoma (GC), respectively. Heparanase (HPSE) and cyclooxygenase (COX)-2 have been proved to play critical roles in inflammation as well as in cancer. The aim was to examine the meaning of their expression in inflammation-related carcinogenesis.

METHODS AND RESULTS

First, expression of HPSE and COX-2 in 78 clinical tissues of Barrett's oesophagus was examined by immunohistochemistry and in situ hybridization. Their expression was increased during the metaplasia-dysplasia sequence with increased neovascularization. Successively, their expression in Barrett's dysplasia was compared with that of GC (22 cases of diffuse-type and 10 of intestinal-type). Interestingly, the expression pattern in Barrett's dysplasia was similar to that in intestinal-type GC, which mainly arises from chronic inflammation. Furthermore, cultured cell lines isolated from differentiated GC tissues, which are often found to be of intestinal-type, revealed up-regulated mRNA expression of HPSE and COX-2.

CONCLUSIONS

HPSE and COX-2 are preferentially up-regulated in Barrett's oesophagus and intestinal-type GC. These molecules may play an important role during the development of inflammation-related adenocarcinoma of the upper gastrointestinal tract.

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.

Mouse gastric tumor models with prostaglandin E2 pathway activation show similar gene expression profiles to intestinal-type human gastric cancer

Background

Gastric cancers are generally classified into better differentiated intestinal-type tumor and poorly differentiated diffuse-type one according to Lauren's histological categorization. Although induction of prostaglandin E₂ pathway promotes gastric tumors in mice in cooperation with deregulated Wnt or BMP signalings, it has remained unresolved whether the gastric tumor mouse models recapitulate either of human gastric cancer type. This study assessed the similarity in expression profiling between gastric tumors of transgenic mice and various tissues of human cancers to find best-fit human tumors for the transgenic mice models.

Results

Global expression profiling initially found gastric tumors from COX-2/mPGES-1 (C2mE)-related transgenic mice (K19-C2mE, K19-Wnt1/C2mE, and K19-Nog/C2mE) resembled gastric cancers among the several tissues of human cancers including colon, breast, lung and gastric tumors. Next, classification of the C2mE-related transgenic mice by a gene signature to distinguish human intestinal- and diffuse-type tumors showed C2mE-related transgenic mice were more similar to intestinal-type compared with diffuse one. We finally revealed that induction of Wnt pathway cooperating with the prostaglandin E₂ pathway in mice (K19-Wnt1/C2mE mice) further reproduce features of human gastric intestinal-type tumors.

Conclusion

We demonstrated that C2mE-related transgenic mice show significant similarity to intestinal-type gastric cancer when analyzed by global expression profiling. These results suggest that the C2mE-related transgenic mice, especially K19-Wnt1/C2mE mice, serve as a best-fit model to study molecular mechanism underlying the tumorigenesis of human gastric intestinal-type cancers.

Inflammation and cancer: how friendly is the relationship for cancer patients?

Evidence has emerged in the last two decades that at the molecular level most chronic diseases, including cancer, are caused by a dysregulated inflammatory response. The identification of transcription factors such as NF-kappaB, AP-1 and STAT3 and their gene products such as tumor necrosis factor, interleukin-1, interleukin-6, chemokines, cyclooxygenase-2, 5 lipooxygenase, matrix metalloproteases, and vascular endothelial growth factor, adhesion molecules and others have provided the molecular basis for the role of inflammation in cancer. These inflammatory pathways are activated by tobacco, stress, dietary agents, obesity, alcohol, infectious agents, irradiation, and environmental stimuli, which together account for as much as 95% of all cancers. These pathways have been implicated in transformation, survival, proliferation, invasion, angiogenesis, metastasis, chemoresistance, and radioresistance of cancer, so much so that survival and proliferation of most types of cancer stem cells themselves appear to be dependent on the activation of these inflammatory pathways. Most of this evidence, however, is from preclinical studies. Whether these pathways have any role in prevention, progression, diagnosis, prognosis, recurrence or treatment of cancer in patients, is the topic of discussion of this review. We present evidence that inhibitors of inflammatory biomarkers may have a role in both prevention and treatment of cancer.

Cyclooxygenase-2 is an independent prognostic factor in gastric carcinoma patients receiving adjuvant chemotherapy and is not associated with EBV infection

PURPOSE

Cyclooxygenase-2 (COX-2) is believed to be involved in carcinogenesis in patients with chronic gastritis with Helicobacter pylori infection. EBV is detected in approximately 10% of gastric carcinomas and H. pylori induces EBV reactivation in the gastric epithelium. We aimed to evaluate significance of COX-2 in gastric carcinoma occurred in EBV and H. pylori prevalent area.

EXPERIMENTAL DESIGN

Tissue microarray samples from 457 gastric carcinoma patients who underwent gastrectomy and adjuvant chemotherapy were studied with EBER1 in situ hybridization for EBV and immunohistochemistry for COX-2 and other gastric carcinoma-related proteins (hMLH1, E-cadherin, c-erbB, and cyclin D1).

RESULTS

EBV infection was observed in 10.9% of gastric carcinomas and was associated with proximal tumor location, increased numbers of lymph node, and E-cadherin expression (P < 0.01). COX-2 overexpression was closely associated with intestinal histologic type and lower tumor stage (P = 0.01). Univariate analysis showed that pT, pN, lymph node ratio, American Joint Committee on Cancer stage, numbers of negative lymph nodes, and resection margin <1 cm were significant prognostic factors. The Cox proportional hazards regression analysis indicated that lack of COX-2 expression and resection margin <1 cm were independent prognostic factors for disease-free survival (P = 0.008 and 0.03, respectively) and overall survival (P = 0.01 and 0.007, respectively).

CONCLUSIONS

EBV infection is not associated with COX-2 expression or survival in gastric carcinoma. Lack of COX-2 expression is an independent prognostic factor in both overall and disease-free survival in gastric carcinoma. Our results indicate that COX-2 may play a role in the progression of gastric carcinoma regardless of EBV infection and is closely associated with histologic differentiation and prognosis.

Expression of COX-2 in stomach carcinogenesis

BACKGROUND

Gastric cancer is a frequent cause of cancer in Brazil. The understanding of gastric carcinogenesis is not completely known but the progress of the molecular biology has provided that the initiation and progression of gastric cancer process is a consequence of a cumulative series of multiple gene alterations.

AIM

The aim of the study is to investigate the relationship among cytoplasmatic COX-1 and COX-2, Bcl-2 and nuclear P53 in chronic gastritis, metaplasia, and intestinal and gastric cancer.

PATIENTS AND METHODS

COX-1, COX-2, P53, and Bcl-2 were evaluated by immunohistochemistry in 34 gastric adenocarcinoma (GA) tissues obtained from gastric resection, 21 tissues of patients with chronic gastritis (CG), and 34 with intestinal metaplasia (IM) obtained from endoscopic biopsies.

RESULTS

COX-1 and COX-2 were expressed in more than 85% of the tissues. A correlation between COX-1 and COX-2 were observed (r = 0.66). P53 was positive in 29% CG, 20% of IM and in 59 % of GA. Bcl-2 was negative in all the CG, in 88% of IM, and in 85% of GA. P53 staining was expressed more frequently in gastric cancer when compared to CG (p = 0.05) or IM (p = 0.003). The expression of Bcl-2 was also higher in gastric cancer (p = 0.002) and in intestinal metaplasia (p = 0.04) when compared to CG. There were no difference between metaplasia and chronic gastritis for P53 or Bcl-2. The immunoreactivity of COX-2 in gastric cancer was higher in the intestinal type (58%) than in diffuse type. A higher expression of COX-2 was found in advanced gastric cancer (p = 0.019). P53 was also more frequent in node positive cancer (p = 0.04).

CONCLUSION

COX-2 is probably involved in gastric carcinogenesis, being an early alteration in cancer. Although we observed in this study a correlation between COX-2 and depth of cancer, this association as a prognostic marker is not well defined. P53 and Bcl-2 was expressed mainly in gastric cancer, being probably a latest alteration in gastric development.

Phenotypic differences between esophageal and gastric intestinal metaplasia

Intestinal metaplasia is a cancer precursor in the esophagus and the stomach. Marked differences exist between the carcinogenic processes in the two locations in terms of natural history and clinical significance. We investigated biopsies from 52 patients with Barrett's esophagus and from 50 patients with gastric intestinal metaplasia in an attempt to throw light on their pathogenic processes. Morphologic characteristics, presence of Helicobacter pylori (H. pylori), and markers of differentiation, inflammation, and proliferation were evaluated by histochemical and immunohistochemical techniques. The area covered by incomplete type of intestinal metaplasia and the proportion of sulfomucins were significantly higher in the esophagus than in the stomach. Immunoreactivity with MUC1, MUC2, MUC5AC, Das-1, cytokeratins 7 and 20, inducible nitric oxide synthase and cyclooxygenase-2 antibodies was also significantly greater in Barrett's esophagus than in gastric intestinal metaplasia. In gastric intestinal metaplasia, the presence of MUC1, MUC5AC, Das-1 and cytokeratin 7 was restricted to areas with the incomplete type of metaplasia. Cell proliferation (Ki-67) was significantly higher in Barrett's esophagus than in gastric intestinal metaplasia. H. pylori was absent in all of the patients with Barrett's esophagus, while it was present in 70% of the patients with gastric intestinal metaplasia. Our observations made clear that Barrett's esophagus shares some phenotypic characteristics with gastric intestinal metaplasia, leading us to suggest that both could arise in response to injuries with eventual carcinogenic potential. However, the progression to more advanced lesions could be modulated by the nature of the carcinogenic insult.

Cyclooxygenase-2 expression and its association with angiogenesis, Helicobacter pylori, and clinicopathologic characteristics of gastric carcinoma

Cyclooxygenase-2 (COX-2) is upregulated in gastric carcinoma, and its increased levels were found to have a prognostic significance in some studies. Both angiogenesis and Helicobacter pylori infection have been reported to be associated with COX-2 expression of gastric cancer in recent studies. In this study, COX-2 expression and its association with CD31 staining, H.-pylori infection, and well-known clinicopathological factors were investigated in 65 gastric cancer patients. COX-2 and CD31 expression assessment was done by immunohistochemical methods. Whartin Starry stain was performed for H.-pylori infection. Of 65 patients, 32 (49%) revealed intense COX-2 immunostaining. Among various clinicopathologic characteristics, COX-2 expression was inversely correlated with tumor size, TNM stage, and lymph node status. Thirty-two (49%) patients revealed intense CD31 immunostaining. Among various clinicopathologic characteristics, CD31 expression was associated only with lymph node metastasis. COX-2 expression was not correlated with CD31 staining and H.-pylori infection. Both COX-2 and CD31 staining had no prognostic significance. In conclusion, we found that COX-2 expression was significantly higher in earlier stages of gastric cancer. It can be suggested that COX-2 expression may be important in the initial development of gastric cancer but not in progression of the disease. Other factors which may be associated with COX-2 in gastric cancer, including angiogenesis and H.-pylori infection, should be investigated in further studies.

Gastric adenomas: relationship between clinicopathological findings, Helicobacter pylori infection, APC mutations and COX-2 expression

Gastric adenomas are rare neoplastic growths characterized by localized polypoid proliferations of dysplastic epithelium that tend to progress to infiltrating adenocarcinoma. Therefore, the identification of molecular markers that could reliably recognize adenomas at risk of progression is advocated in the clinical management. In this study we investigated, in a series of gastric adenoma specimens from an area at high risk of gastric cancer, the relationship between clinicopathological characteristics of adenoma and Helicobacter pylori infection, APC mutational status, and COX-2 and the down-stream enzyme mPGES1 expression. Helicobacter pylori infection, detected in 24%, and 33% by histology and PCR analyses, respectively, did not show any relationship with growth pattern, localization, size, dysplasia grade and presence of synchronous cancer. Pathogenetic mutations of MCR region (codons 1269-1589) of the APC gene were detected only in one case corresponding to a single, small size, low grade, H. pylori-negative adenoma. The expression of COX-2 largely matched that of mPGES(1). Both were overexpressed in 79% of cases showing a relationship with high-grade dysplasia, size >10 mm and presence of a synchronous carcinoma. In conclusion, COX-2 may play a key role in the development and progression of gastric adenoma and could be an attractive target in the management of gastric adenoma at major risk of cancer development.

Function and recruitment of mucosal regulatory T cells in human chronic Helicobacter pylori infection and gastric adenocarcinoma

CD4(+)CD25(high) FOXP3-expressing regulatory T cells (Treg) can suppress immune responses to infections and tumors, thereby promoting microbial persistence and tumor progression. However, little is known about the phenotype and function of human mucosal Treg. Therefore, we analyzed the suppressive activity and homing phenotype of Treg in gastric mucosa of Helicobacter pylori-infected gastric adenocarcinoma patients. We found increased numbers of CD4(+)FOXP3(+) Treg in the tumor compared to tumor-free gastric mucosa. Gastric Treg cells were able to suppress H. pylori-induced T cell proliferation and IFN-gamma production. Furthermore, gastric Treg expressed increased levels of l-selectin and CCR4, compared to non-Treg cells, suggesting that these receptors contribute to Treg recruitment. The presence of functional antigen-specific Treg in H. pylori-infected gastric mucosa supports an important role for these cells in suppression of mucosal effector T cell responses, which probably contribute to bacterial persistence and possibly also to gastric tumor progression.

Non-steroidal anti-inflammatory drugs in prevention of gastric cancer

Non-steroidal anti-inflammatory drugs (NSAIDs) including cyclooxygenase 2 (COX-2) selective inhibitors, are potential agents for the chemoprevention of gastric cancer. Epidemiological and experimental studies have shown that NSAID use is associated with a reduced risk of gastric cancer although many questions remain unanswered such as the optimal dose and duration of treatment. The possible mechanisms for the suppressor effect of NSAIDs on carcinogenesis are the ability to induce apoptosis in epithelial cells and regulation of angiogenesis. Both COX-dependent and COX-independent pathways have a role in the biological activity of NSAIDs. Knowledge of how NSAIDs prevent neoplastic growth will greatly aid the design of better chemopreventive drugs and novel treatments for gastric cancer.

Role of cyclooxygenase-2 in the carcinogenesis of gastrointestinal tract cancers: A review and report of personal experience

Selective cyclooxygenase (COX)-2 inhibitors (coxibs) were developed as one of the anti-inflammatory drugs to avoid the various side effects of non-steroidal anti-inflammatory drugs (NSAIDs). However, coxibs also have an ability to inhibit tumor development of various kinds the same way that NSAIDs do. Many experimental studies using cell lines and animal models demonstrated an ability to prevent tumor proliferation of COX-2 inhibitors. After performing a randomized study for polyp chemoprevention study in patients with familial adenomatous polyposis (FAP), which showed that the treatment with celecoxib, one of the coxibs, significantly reduced the number of colorectal polyps in 2000, the U.S. Food and Drug Administration (FDA) immediately approved the clinical use of celecoxib for FAP patients. However, some coxibs were recently reported to increase the risk of serious cardiovascular events including heart attack and stroke. In this article we review a role of COX-2 in carcinogenesis of gastrointestinal tract, such as the esophagus, stomach and colorectum, and also analyze the prospect of coxibs for chemoprevention of gastrointestinal tract tumors.

Effects of celecoxib on cell proliferation and ERK2 expression of ERK2 in gastric cancer cells

AIM: To explore the role of celecoxib, a selective COX-2 inhibitor, in the proliferation of human gastric carcinoma cells SGC7901, and to investigate the relationship between cell proliferation and the expression of extracellular signal-regulated kinase 2 (ERK2).

METHODS: The cell proliferation of SGC7901 cells was measured by MTT assay, and the apoptoticsis rate of the cells was examined by TUNEL staining method and flow cytometry. The expression of phosphated ERK2 was detected by immunohistochemistry and quantified measured by image analysis systems.

RESULTS: Celecoxib inhibited the proliferation of SGC7901 gastric carcinoma cells and the expression of phosphated ERK2, as well as induced the apoptosis of the SGC-7901 cells in a dose-dependent manner. The growth inhibitory rates of SGC-7901 cells treated with 10, 20, 40, 80 and, 160 μmol/L celecoxib for 48 h were 9.8%, 30%, 58.9%, 76.3%, and 88.3%, respectively. The SGC7901 cells presented typical morphological features of apoptosis by TUNEL staining. By flow cytometry, the apoptosistic rates of SGC-7901 cells (4.23 ± 0.81%, 15.50 ± 2.10%, 24.35 ± 2.32%, 31.52±3.64%, and 45.82±5.92% for 10, 20, 40, 80 and 160 μmol/L celecoxib, respectively) were significantly higher than those inof the control group(1.85 ±0.31%, P < 0.01). The optical density value of ERK2 of SGC7901 cells (10, 20, 40, 80 and 160 μmol/L celecoxib: 2.96 ± 0.24, P >0.05; 2.56 ± 0.24, P<0.05; 2.04 ± 0.20, P < 0.01; 1.68 ± 0.16, P < 0.01; 1.52 ± 0.09, P < 0.01) were significantly lower than that ofin the control group (3.32 ± 0.28).

CONCLUSION: Celecoxib can inhibit the growth and induce the apoptosis of SGC7901 cells, and its mechanism may and induce the cell apoptosis. This effect may relate to the inhibition of ERK2 kinase signaling pathway.

Expression of cyclooxygenase-2 in gastric cancer and its relation to liver metastasis and long-term prognosis

AIM: To investigate the expression of cyclooxygenase-2 (COX-2) in gastric cancer and its relation with the liver metastasis and prognosis.

METHODS: Expression of COX-2 mRNA and protein was examined in gastric cancer and its paired substantial normal tissue by semi-quantitative reverse transcription-polymerase chain reaction and immunohistochemistry. The relation between COX-2 expression and prognosis was investigated in 195 cases.

RESULTS: The expression of COX-2 mRNA in gastric cancer tissue was significantly higher than that in normal tissue in 47 cases (w = 792, P<0.01). The COX-2 mRNA in pT3-4 tissue expressed higher than that in pT1-2 tissue (w = 204, P<0.05). The positive expression rate of COX-2 protein was 57.9% (113/195). The COX-2 expression was significantly related to histological type, lymphnode metastasis, venous invasion and liver metastasis (P<0.05). No relation was found between COX-2 expression and invasion depth, peritoneal metastasis and International Union against Cancer TNM stage. The multiple regression analysis showed that the COX-2 expression and venous invasion were obviously associated with liver metastasis (P<0.05). However, there was no significant correlation between COX-2 immunoreactivity and prognosis.

CONCLUSION: COX-2 may play an important role in the development of gastric cancer, and the over-expression of COX-2 protein may be a high risk factor for liver metastasis.

Correlation of platelet-derived endothelial cell growth factor/ thymidine phosphorylase and Cox-2 expression to angiogenesis and apoptosis in gastric carcinoma

AIM: To investigate the relationship of the expression of platelet-derived endothelial cell growth factor/thymidine phosphorylase (PD-ECGF/TP) and Cox-2 to angiogenesis and apoptosis in gastric carcinoma.

METHODS: The expression of PD-ECGF and Cox-2 and the microvascular density (MVD) level were examined by immunohistochemical staining, and apoptotic index (AI) was examined by flow cytometry in 67 cases of gastric carcinoma.

RESULTS: There was a close correlation between PD-ECGF expression and several clinicopathological factors including lymph node metastasis (P < 0.05), histology (P < 0.05) and histological type (P < 0.05). The expression of Cox-2 was closely related to lymph node metastasis (P < 0.05); The expression of PD-ECGF or Cox-2 in gastric cancer tissues was positively correlated with MVD (P < 0.01) and negatively correlated with AI (P < 0.01). Combined analysis of PD-ECGF and Cox-2 showed that tumors with positive expression of both factors had a significantly lower AI and a significantly higher MVD than tumors with negative expression of both factors (P < 0.01).

CONCLUSION: Up-regulation of PD-ECGF and Cox-2 may facilitate tumor angiogenesis and inhibit apoptosis in gastric carcinoma, indicating cooperation between PD-ECGF and Cox-2 in gastric cancer, and therefore promote tumor growth and metastasis.

Expression of COX-2 proteins in gastric mucosal lesions

AIM: To investigate the expression of COX-2 proteins in gastric mucosal lesions and to assess the relationship between COX-2 expression and type, pathologic stage, differentiation, or lymph node metastasis in gastric cancer and the relationship between COX-2 expression and H pylori infection in gastric mucosal lesions.

METHODS: Thirty patients with gastric carcinoma underwent surgical resection. Samples were taken from tumor site and paracancerous tissues, and ABC immunohistochemical staining was used to detect the expression of COX-2 proteins. H pylori was determined by rapid urea test combined with pathological stating/¹⁴C urea breath test.

RESULTS: The positive rate and staining intensity of mutant COX-2 gene expression in gastric cancer were significantly higher than those in paracancerous tissues (66.7% vs 26.7%) (P < 0.01, P < 0.001). There was a significant correlation between COX-2 and pathologic stage or lymph node metastasis type of gastric carcinoma (76.0% vs 20.0%, 79.2% vs 16.7%) (P < 0.05). No correlation was found between COX-2 expression and type or grade of differentiation (P > 0.05). COX-2 expression of intestinal metaplasia (IM) or dysplasia (DYS) with positive H pylori was significantly higher than that with negative H pylori (50.6% vs 18.1%, 60.0% vs 33.3%) (P < 0.05).

CONCLUSION: COX-2 overexpression was found in a large proportion of gastric cancer tissues compared with matched non-cancerous tissues and was significantly associated with advanced tumor stage and lymph node metastasis. Overexpression of COX-2 plays an important role in tumor progression of gastric cancer. COX-2 may also play a role in the early development/promotion of gastric carcinoma and is associated with H pylori infection.

Chemoprevention of gastric cancer: role of COX-2 inhibitors and other agents

Despite the decrease in incidence, gastric cancer remains the second leading cause of cancer-related death worldwide. Prevention is likely to be the most effective means of not only reducing the incidence but also mortality from this disease. The term 'chemoprevention' has been referred to the prevention of cancer using specific agents to suppress or reverse the carcinogenic process. In recent years, attention has been focused on the anticancer properties of non-steroidal anti-inflammatory drugs (NSAIDs), Helicobacter pylori eradication therapy and diet life-style. In vitro and in vivo studies show that widespread and long-term use of NSAIDs may be adopted in the healthy population for gastric chemoprevention. Albeit, enthusiasm has been thwarted by the potential toxic effects, i.e., risk of peptic ulcer disease. The new NSAIDs, selective cyclooxygenase-2 inhibitors, causing less injury to the mucosa of the upper gastrointestinal tract may be a valid alternative. However, fundamental questions such as safety, efficacy, mechanisms of actions, and optimal treatment regimens need to be defined. H. pylori triggers gastric carcinogenesis, however, cost-effect analyses suggest that only a subgroup of H. pylori-infected subjects present beneficial changes following eradication therapy. Diet plays an important role in the pathogenesis of gastric cancer either increasing the risks of or protecting against, cancer development. Thus, a reasonable suggestion for the general population is a natural chemoprevention based on life-style 'eat to live, not live to eat'.

Cyclooxygenase-2 and gastric carcinogenesis

Epidemiological studies have shown that the use of nonsteroid anti-inflammatory drugs (NSAIDs) is associated with reduced risk of gastric cancer. The best-known target of NSAIDs is the cyclooxygenase (Cox) enzyme. Two Cox genes have been cloned, of which Cox-2 has been connected with gastric carcinogenesis. Expression of Cox-2 is elevated in gastric adenocarcinomas, which correlates with several clinicopathological parameters, including depth of invasion and lymph node metastasis. This suggests that Cox-2-derived prostanoids promote aggressive behavior of adenocarcinomas of the stomach. Cox-2 expression is especially prominent in intestinal-type gastric carcinoma and it is already present in dysplastic precursor lesions of this disease, which suggests that Cox-2 contributes to gastric carcinogenesis already at the preinvasive stage. Our most recent data show that Cox-2 is expressed in gastric adenomas of trefoil factor 1 deficient mice. Treatment of these mice with a Cox-2 selective inhibitor, celecoxib, reduced the size of the adenomas. Taken together these data support efforts to initiate clinical studies to investigate the effect of Cox-2 inhibitors as chemotherapeutic agents and as adjuvant treatment modalities against gastric neoplasias.

Susceptibility and biomarker knowledge for improvement of environmental health

At the international level, environmental health problems are usually most serious in countries that have the least resources to deal with the problems. Therefore, international efforts have been initiated to achieve equitable environmental health globally. One approach is to conduct international collaborative studies. This approach has been successful in the building of scientific infrastructure in these countries so that they can address their own environmental health concerns and to sustain the environmental health programs. Using liver and oral cancers as models for discussion, examples of success in the identification of etiology and the mechanisms for the diseases are provided. For example, biomarkers are used to provide early warning signals for the disease. In addition, the application of the collected information for developing disease prevention and intervention programs is presented. Expertise in genetic susceptibility is used to provide a more precise understanding of the cancer process. With the precise knowledge, the information can potentially be used to screen for high-risk individuals and to develop "designer" intervention procedures against specific biochemical defects. Success in disease prevention is dependent upon multidisciplinary collaborations at the local and international levels.

Cyclooxygenase-2 expression is associated with well-differentiated and intestinal-type pathways in gastric carcinogenesis

BACKGROUND/AIMS

Cyclooxygenase-2 (COX-2) expression appears to be increased in several different types of human cancers, suggesting that the presence of COX-2 is associated with carcinogenesis. Recently, increased expression of COX-2 has been frequently detected in gastric cancer, and this may have prognostic significance. In the present study, we aimed to analyze the expression of COX-2 in a much larger sample to determine whether COX-2 expression is related to the clinicopathological features and survival rates of patients with gastric cancer.

METHODS

We investigated 140 patients with gastric cancer who underwent surgery between January 1992 and December 1993 and examined the expression of COX-2 in human gastric cancer tissue by immunohistochemistry.

RESULTS

COX-2 expression was present in the cytoplasm of tumor cells but not in normal gastric epithelia. Positive expression of COX-2 was detected in 86 of 140 gastric cancers analyzed (61.4%). Positive expression of COX-2 correlated with the depth of tumor invasion (p = 0.015). However, there was no association between COX-2 expression and tumor stage or status of lymph node or distant metastasis. Furthermore, COX-2 expression was not associated with patient survival (p = 0.816). Positive expression of COX-2 occurred more frequently in intestinal than in diffuse or mixed types of cancer and correlated with tumor differentiation (p < 0.001, p = 0.001, respectively).

CONCLUSION

These results suggest that COX-2 may play an important role in the evolution of gastric carcinogenesis and be associated with well-differentiated and intestinal type pathways in gastric carcinogenesis. However, COX-2 expression seems to be less useful for establishing prognosis for gastric cancer.

Association of cyclooxygenase-2 expression with Hp-cagA infection in gastric cancer

AIM: To observe the expression of cyclooxygenase-2 (COX-2) and to investigate the association between COX-2 expression and infection with cytotoxic-associated gene A (cagA) positive strain Helicobacter pylori (Hp) in human gastric cancer, and subsequently to provide fresh ideas for the early prevention of gastric cancer.

METHODS: 32 Specimens of gastric cancer and corresponding adjacent normal gastric mucosa were obtained from patients who had undergone surgical operations of gastric cancer. All the samples including 1 case of stomach malignant lymphoma and 31 cases of gastric adenocarcinoma were confirmed by pathology diagnosis. The expression of COX-2 in 32 specimens of gastric cancer and corresponding adjacent normal gastric mucosa was quantitatively determined and analyzed with Flow Cytometry, and the levels of COX-2 protein were compared between specimens with cagA⁺Hp infection and those without cagA⁺Hp infection. The cagA gene in 32 specimens of gastric cancer was detected by polymerase chain reaction (PCR) method.

RESULTS: Twenty-seven of 32 (84%) specimens of gastric cancer showed over-expression of COX-2, compared with the adjacent normal gastric mucosa. cagA⁺ gene were detected from 19 specimens of gastric cancer, but not from the other 13 specimens. The levels of COX-2 protein in 19 specimens of gastric cancer with cagA⁺Hp infection (the number of positive cells was 73.82 ± 18.2) were significantly higher than those in the 13 specimens without cagA⁺Hp infection (the number of positive cells was 35.92 ± 22.1).

CONCLUSION: COX-2 is overexpressed in gastric cancer and cagA⁺Hp infection could up-regulate the expression of COX-2 in gastric cancer in human. There may also exist another way or channel to regulate the expression of COX-2 in gastric cancer in addition to cagA⁺Hp infection. Therefore, applying COX-2 selective inhibitors could be an effective and promising way to prevent gastric cancer.

Cyclooxygenase-2 expression in early gastric cancer, intestinal metaplasia and Helicobacter pylori infection

Cyclooxygenase (COX) is the crucial enzyme for synthesis of prostaglandins and occurs in two isoforms COX-1 and COX-2. Whilst COX-1 is constantly expressed in the gastrointestinal tract in large quantities and probably maintains mucosal integrity through constant generation of prostaglandins, COX-2 is induced principally during inflammation. In early gastric cancer and in intestinal metaplasia the expression of COX-2 in patients infected by Helicobacter pylori is increased in intestinal type compared to diffuse type gastric cancer and in intestinal metaplasia. In tumours of mixed type, COX-2 is also increased in the intestinal component compared to the diffuse component. Whilst there has been success of COX-2 inhibition for chemoprevention in colon cancer, a similar role in gastric cancer needs to be carefully assessed in the light of reported adverse effects and whether the precancerous condition, intestinal metaplasia, can truly regress.