Prognostic significance of expression of cyclooxygenase-2 and vascular endothelial growth factor in human gastric carcinoma

Cyclooxygenase Inhibitors in Epithelial Ovarian Cancer Treatment

Epithelial ovarian cancer (EOC) is the fifth most common cause of cancer mortality among women. At present, EOC is treated with one or in a combination of treatments, commonly debulking surgery, combining a platinum-based and a taxane-based therapy; however, the patients have a risk of injury to the bowel, bladder, ureter, and vessels during surgery and many of them suffer from severe adverse effects caused by chemotherapy. Pharmaceutical inhibition of cyclooxygenase (COX) might be an important therapeutic tool in cancer treatment, as COX contributes to cancer progression by upregulating the levels of downstream metabolites. In this review article, we have discussed the role of COX in cancer progression and the therapeutic use of COX inhibitors in the treatment of EOC with subsequent clinical studies and future management. Usually, gonadotropins can promote prostaglandin E2 production in EOC cells via COX-1 and -2 upregulations through the PI3K/AKT signaling pathway. Several reports have shown that treatment of EOC cells with COX-1- and COX-2-specific inhibitors exhibits a therapeutic effect on EOC both in vitro and in vivo. However, more clinical investigations are needed to develop therapeutic COX inhibitors for the prevention and treatment of EOC without adverse effects.

Cyclooxygenase-2 in gastrointestinal malignancies

Cyclooxygenase (COX) is an enzyme complex that plays an important role in the conversion of arachidonic acid to prostaglandins. Prostaglandins are essential modulators of signal transduction pathways, which contribute to the metastatic properties of gastrointestinal (GI) malignancies. Although COX-1 is constitutively active, COX-2 is upregulated by cytokines, growth factors, and mitogen. COX-2 is involved in malignant cell proliferation, angiogenesis, migration, invasion, and antiapoptotic activity. Thus, COX-2 inhibitors may represent a promising therapeutic strategy for the treatment of GI cancers. In this review, the role of COX-2 in GI cancers is explored, and its clinical applications as a therapeutic target are discussed.

Current Targeted Therapies in HER2-Positive Gastric Adenocarcinoma

Gastric cancer is one of the most common types of cancer in the world, usually diagnosed at an advanced stage. Despite the advances in specific anticancer agents' development, the survival rates remain modest, even in early stages. In 15%-20% of cases, the human epidermal growth factor receptor 2 (HER2) overexpression was identified. We conducted a general review to summarize the progress that has been made in the targeted treatment of HER2-positive esogastric junction or gastric adenocarcinoma. According to our findings, trastuzumab is the only validated anti-HER2 agent in locally advanced or metastatic disease and its adjuvant effectiveness is assessed in a RTOG phase III study. In a previously treated advanced disease, the maytansine derivate TDM 1 failed to be approved as a second-line regimen, and the tyrosine kinase inhibitor, lapatinib, shows modest results. The antiangiogenics have not been analyzed in specific populations and targeting the mesenchymal-epithelial transition factor (MET) receptor, overexpressed in up to 46% of the advanced disease, seems encouraging. Regarding the checkpoint inhibitors, based on KEYNOTE 059 multilevel ongoing trial, stratified according to the HER2 and programmed death-ligand (PD-L) 1 status, pembrolizumab was approved for third-line treatment of gastric or gastroesophageal junction adenocarcinoma.

Correlation between HGF/c-Met and Notch1 signaling pathways in human gastric cancer cells

In recent decades, research concerning gastric carcinogenesis has rapidly progressed. It is evident that hepatocyte growth factor (HGF) is clinically related to gastric cancer progression and metastasis. In addition, previous studies have found that expression of Notch ligand Jagged1 is correlated with the poor prognosis of gastric cancer. However, the interaction between the HGF/c-Met and Notch1 signaling pathways remains unknown. In the present study, we found that gastric cancer patients with positive c-Met expression exhibited poorer overall survival than patients without c-Met expression (P=0.043) and that Jagged1 expression was significantly correlated with c-Met expression (r=0.301; P=0.004) in human gastric cancer specimens. In addition, Jagged1 activity increased after HGF stimulation, which in turn increased the downstream expression of cyclooxygenase 2 (COX-2) in a time-dependent manner. After knockdown of Notch1 intracellular domain (N1IC), HGF was found to increase the proliferation and migration ability in human gastric cancer cells. However, overexpression of N1IC still had no effect after HGF stimulation. Our study found a feedback loop between HGF/c-Met and Jagged1/Notch1 signaling. Furthermore, both HGF/c-Met and Notch1 signaling triggered COX-2 activity. These results suggest that gastric cancer progression is not associated with a unique signaling pathway and that a feedback loop may exist between the HGF/c-Met and Notch1 signaling pathways, which may result in therapeutic resistance. Therefore, multi-modality therapies should be considered for treating gastric cancer.

Biomarker-driven targeted therapies for gastric/gastro-esophageal junction malignancies

Gastroesophageal malignancies often contain high amounts of genetic and molecular alterations that result in an aggressive disease capable of rapidly metastasizing to distant organs and early development of drug resistance. Most patients in the Western hemisphere present with locally advanced or metastatic disease that is treated with systemic chemotherapy used either in the neoadjuvant or palliative setting, respectively. This article will review the various recent advances in the development of targeted therapies for the treatment of advanced gastric and gastroesophageal cancer.

Correlations between VEGF-A expression and prognosis in patients with gastric adenocarcinoma

Angiogenesis induced by vascular endothelial growth factor A (VEGF-A) plays a critical role in tumor growth and metastasis. The study aimed to evaluate the expression of VEGF-A in gastric adenocarcinoma and investigate its correlations with tumor clinicopathological features and prognostic significance. VEGF-A expression was detected by immunohistochemistry on a tissue microarray containing 90 pairs of human gastric adenocarcinoma and paracancerous tissues. Levels of VEGF-A in gastric adenocarcinoma were significantly higher than those in paracancerous tissues (P=0.018). Furthermore, the result was coincident with that of human gastric adenocarcinoma xenografts in nude-mice (P<0.01). In addition, the VEGF-A expression was positive correlation with TNM stage (P=0.047), tumor size (P=0.028), positive lymph nodes (P=0.002) and lymphovascular invasion (P=0.001). Finally, Kaplan-Meier survival analysis showed that VEGF-A up-regulation indicated a poor prognosis for overall survival (P=0.039). In conclusions, VEGF-A may be used as a biomarker for evaluating both the biological behavior of tumor and the prognosis in patients with gastric adenocarcinoma.

Cyclooxygenase-2 Expression is Associated with Histologic Tumor Type in Canine Mammary Carcinoma

Cyclooxygenase-2 (COX-2) is an inducible member of the family of cyclooxygenase enzymes that has been implicated in the genesis of numerous cancers. The role of COX-2 in canine mammary neoplasia remains to be more clearly elucidated. The goal of the study reported here was to determine whether a direct association between levels of COX-2 expression and tumor histologic subtype exists in canine mammary carcinoma. Immunohistochemical analysis was performed using a polyclonal antiprostaglandin G/H synthase 2 IgG COX-2 antibody. Sections from the kidneys of young dogs, which stain positive for COX-2 in the macula densa, served as positive controls. Slides were reviewed by a single pathologist, and were evaluated for COX-2 expression according to previously established scales. Positive-staining tumors were given a COX-2 staining distribution (on the basis of the percentage of positive staining cells in five 400x fields) and intensity score according to previously established scales. The product of the COX-2 staining distribution and intensity scores was calculated to create a COX-2 staining index. COX-2 expression was detected in 28 of 50 (56%) samples evaluated. Anaplastic carcinomas had a significantly higher COX-2 staining distribution, intensity, and index, compared with those for adenocarcinomas ( P < 0.0001). The overall percentage of positive tumors (56%) was consistent with that of prior studies. To the authors' knowledge, these results indicate, for the first time, a direct association between COX-2 expression and tumor histologic subtype in canine mammary carcinomas. Future research directed at measuring tumor response in canine mammary carcinoma patients treated with a selective COX-2 inhibitor is indicated.

Expression of cyclooxygenase 2 and vascular endothelial growth factor in gastric carcinoma: Relationship with clinicopathological parameters

BACKGROUND

Gastric cancer is one of the most common cancers and the second most common cause of cancer-related death worldwide. Identification of specific prognostic indicators might allow a better prognostic stratification and more effective therapy.

AIM

To assess the expression and relationship between COX-2 and VEGF protein in gastric adenocarcinoma and whether these markers are useful in predicting clinicopathological prognostic parameters.

MATERIALS AND METHODS

The study included 83 formalin-fixed paraffin embedded tissue samples of excised gastric adenocarcinoma and 20 non tumorous tissue controls. The slides were subjected to COX-2 and VEGF immunohistochemical staining using a streptavidin-biotinperoxidase according to the manufacturer's protocol. The results were assessed independently by two pathologists. The relationships among COX-2 and VEGF expression and clinicopathological parameters were statistically analyzed.

RESULTS

COX-2 and VEGF expressions were obviously higher in carcinoma tissues compared to normal mucosae (p<0.001). The expression rate of COX-2 was 54.2% and of VEGF was 68.7%. COX-2 positive tumors were significantly correlated with Lauren classification, tumor depth and Helicobacter pylori infection (p<0.001, p=0.008, p=0.035). VEGF was significantly associated with lymph node metastasis and tumor depth (p<0.001). There was a positive association between VEGF and COX-2 expression in gastric adenocarcinoma (Kappa value=0.55).

CONCLUSION

In gastric adenocarcinoma, COX-2 expression might serve as a powerful indicator for intestinal type carcinoma, locally advanced disease and H. pylori infection, while VEGF was related to loco-regional progression. COX-2 might be involved in the development of angiogenesis in gastric carcinoma through VEGF upregulation.

Current and emerging therapies in unresectable and recurrent gastric cancer

Gastric cancer is one of the most lethal cancers worldwide despite many advances and options in therapy. As it is often diagnosed at an advanced stage, prognosis is poor with a median overall survival of less than twelve months. Chemotherapy remains the mainstay of treatment for these patients but it confers only a moderate survival advantage. There remains a need for new targeted treatment options and a way to better define patient populations who will benefit from these agents. In the past few years, there has been a better understanding of the biology, molecular profiling, and heterogeneity of gastric cancer. Our increased knowledge has led to the identification of gastric cancer subtypes and to the development of new targeted therapeutic agents. There are now two new targeted agents, trastuzumab and ramucirumab, that have recently been approved for the treatment of advanced and metastatic gastric cancer. There are also many other actively investigated targets, including epidermal growth factor receptor, the phosphatadylinositol 3-kinase/protein kinase B/mammalian target of rapamycin pathway, c-Met, poly ADP-ribose polymerase, and immune checkpoint inhibition. In this review, we discuss the current management of advanced gastric cancer as well as emerging targeted therapies and immunotherapy.

Regulation of COX-2 expression and epithelial-to-mesenchymal transition by hypoxia-inducible factor-1α is associated with poor prognosis in hepatocellular carcinoma patients post TACE surgery

Currently, it is not entirely clear whether hypoxia-inducible factor-1α (HIF-1α) is involved in the regulation of COX-2 expression and epithelial-to-mesenchymal transition (EMT), and whether these events affect the prognosis of hepatocellular carcinoma (HCC) patients treated with transcatheter arterial chemoembolization (TACE). In this report the relationship between HIF-1α and COX-2 protein expression, EMT in tumor specimens from HCC patients after TACE surgery and the clinical significance of HIF-1α and COX-2 expression were analyzed using statistical approaches. HepG2 cells treated with CoCl₂ was employed as a hypoxia cell model in vitro to study hypoxia-induced HIF-1α, COX-2 expression, and EMT alteration. The results showed that HIF-1α and COX-2 protein expression increased in HCC tissues after TACE surgery. Moreover, there was positive correlation between upregulation of HIF-1α and COX-2. Elevated expression of HIF-1α increased both Snail and Vimentin protein expression, while it reduced E-cadherin protein expression. It was further verified that hypoxia enhanced protein expression of HIF-1α and COX-2 in HepG2 cells treated with CoCl₂. Upregulation of HIF-1α and COX-2, together with EMT alteration resulted in increased migration and invasion of HepG2 cells under hypoxia. In conclusion, TACE surgery results in aggravated hypoxia status, leading to increased HIF-1α protein expression in HCC tissue. To adapt to hypoxic environment, HIF-1α stimulates COX-2 protein expression and promotes EMT process in hepatocellular cancer cells, which enhances HCC invasion and metastasis, and might contribute to poor prognosis in HCC patients post TACE treatment.

Correlation of 15-prostagladin dehydrogenase expression with clinicopathological factors and survival rate in gastric adenocarcinoma

INTRODUCTION

The prostaglandin (PG) E2 level, which is associated with oncogenesis, progression and metastasis in various types of cancer, is determined by reciprocal regulation of 15-prostaglandin dehydrogenase (15-PGDH) and cyclooxygenase-2. This study investigated 15-PGDH expression in gastric adenocarcinoma, the associations between 15-PGDH expression and clinicopathological factors, and the correlation between 15-PGDH expression and the 5-year gastric-cancer-specific survival rate (5-year GCSS).

METHODS

From 175 patients who underwent gastrectomy, we obtained biopsies of gastric adenocarcinoma tissues and adjacent normal tissues for preparation as formalin-fixed, paraffin-embedded specimens and conducted an immunohistochemical analysis.

RESULTS

15-PGDH expression was low in 65.1% of cases. 15-PGDH expression showed no relationship with age or gender, but was significantly correlated with the pathologic type, T stage, N stage, TNM stage, positive lymph node metastasis, metastasis to a larger quantity of lymph nodes, positive lymphatic invasion, positive vascular invasion, positive perineural invasion, and palliative gastrectomy. The 5-year GCSS of the low-expression group was 77.19% and a lower level of 15-PGDH expression correlated to a lower 5-year GCSS. 15-PGDH expression significantly influenced the 5-year GCSS on univariate but not multivariate analysis.

CONCLUSION

Our findings indicate that 15-PGDH expression was low in gastric adenocarcinoma and was correlated with the clinicopathological factors associated with prognosis and a more advanced stage of gastric adenocarcinoma. Also, 15-PGDH expression was significantly associated with the 5-year GCSS, but was not an independent prognostic factor thereof.

The prognostic value of pSTAT3 in gastric cancer: a meta-analysis

INTRODUCTION

The prognostic value of pSTAT3 in gastric cancer has been assessed for years while the results remain controversial and heterogeneous. Therefore, we conducted this meta-analysis to determine the prognostic effect of pSTAT3 in gastric cancer patients.

METHODS

We searched PubMed, Embase and Web of Science and eight studies comprising 1314 gastric cancer patients were included in our meta-analysis. Hazard ratios (HRs) with 95 % confidence interval (95 % CI) were extracted to perform meta-analysis on the overall survival. Subgroup analysis according to study location, publication year, number of patients and quality score of studies were also investigated.

RESULTS

Our results revealed that pSTAT3-positive patients had a significant increase in mortality risk as compared to pSTAT3-negative patients in the random-effects model (combined HR 1.87, 95 % CI 1.28-2.74). However, our result showed no statistically significant association between pSTAT3 and clinicopathological characteristics (TMN stage, lymph node metastasis, grade of differentiation, Lauren classification and distant metastasis) of gastric cancer.

CONCLUSION

In conclusion, our meta-analysis suggests that positive expression of pSTAT3 is associated with poor prognosis in gastric cancer patients.

Phase I Study of Axitinib in Combination with Cisplatin and Capecitabine in Patients with Previously Untreated Advanced Gastric Cancer

PURPOSE

This phase I trial evaluated the question of whether the standard starting dose of axitinib could be administered in combination with therapeutic doses of cisplatin/capecitabine in patients with previously untreated advanced gastric cancer, and assessed overall safety, pharmacokinetics, and preliminary antitumor activity of this combination.

MATERIALS AND METHODS

Patients in dose level (DL) 1 received axitinib 5 mg twice a day (days 1 to 21) with cisplatin 80 mg/m(2) (day 1) and capecitabine 1,000 mg/m(2) twice a day (days 1 to 14) in 21-day cycles. Maximum tolerated dose (MTD) was the highest dose at which ≤ 30% of the first 12 patients experienced a dose-limiting toxicity (DLT) during cycle 1. Ten additional patients were enrolled and treated at the MTD in order to obtain additional safety and pharmacokinetic data.

RESULTS

Three DLTs occurred during cycle 1 in three (25%) of the first 12 patients: ruptured abdominal aortic aneurysm, acute renal failure, and > 5 consecutive days of missed axitinib due to thrombocytopenia. DL1 was established as the MTD, since higher DL cohorts were not planned. Common grade 3/4 non-hematologic adverse events in 22 patients treated at DL1 included hypertension (36.4%) and decreased appetite and stomatitis (18.2% each). Cisplatin/capecitabine slightly increased axitinib exposure; axitinib decreased capecitabine and 5-fluorouracil exposure. Eight patients (36.4%) each had partial response or stable disease. Median response duration was 9.1 months; median progression-free survival was 3.8 months.

CONCLUSION

In patients with advanced gastric cancer, standard doses of axitinib plus therapeutic doses of cisplatin and capecitabine could be administered in combination. Adverse events were manageable.

COX-2 Inhibitors and Gastric Cancer

The evidence that cyclooxygenase-2 (COX-2) is upregulated and plays an important role in carcinogenesis of gastric cancer has triggered the topic of COX-2 inhibitors as chemopreventive agents for gastric cancer. Studies find that COX-2 inhibitors are associated not only with chemoprophylactic effects, but also with chemotherapeutic potentials in gastric cancer. Both COX-dependent and COX-independent pathways have a role in the anticancer efficiency of COX-2 inhibitors. However, enthusiasm is thwarted by the potential toxicity, that is, gastrointestinal toxicity of nonselective COX-2 inhibitors and cardiovascular risk of selective COX-2 inhibitors. Therefore, more studies are needed to develop new targeted antitumor agents (such as prostaglandin E receptor antagonist) and to define fundamental questions such as optimal treatment regimens, integration of cotherapy, and careful selection of candidates.

Prognostic value of vascular endothelial growth factor A expression in gastric cancer: a meta-analysis

Vascular endothelial growth factor A (VEGF-A) is considered as a prime mediator of angiogenesis and has been implicated in carcinogenesis and metastasis. Various studies examined the relationship between VEGF-A overexpression with the clinical outcome in patients with gastric cancer, but yielded conflicting results. Electronic databases updated to September 2013 were searched to find relevant studies. A meta-analysis was conducted with eligible studies which quantitatively evaluated the relationship between VEGF-A overexpression and survival of patients with gastric cancer. Survival data were aggregated and quantitatively analyzed. We performed a meta-analysis of 20 studies that evaluated the correlation between VEGF-A overexpression and survival in patients with gastric cancer. Combined hazard ratios suggested that VEGF-A overexpression had an unfavorable impact on overall survival (OS) (hazard ratio [HR] = 1.57; 95% confidence interval [CI], 1.30–1.84) and disease-free survival (DFS) (HR = 1.85; 95% CI, 1.39–2.32) in patients with gastric cancer. No significant heterogeneity (P = 0.487) was observed among 16 studies for OS and among 7 studies for DFS (P = 0.435). VEGF-A overexpression indicates a poor prognosis for overall survival and disease-free survival in patients with gastric cancer.

Cyclooxygenase 2 in gastric carcinoma is expressed in doublecortin- and CaM kinase-like-1-positive tuft cells

Background/Aims

Doublecortin and CaM kinase-like-1 (DCAMKL1) is a marker of stem cells expressed predominantly in the crypt base in the intestine. However, DCAMKL1-positive cells have been shown to be differentiated tuft cells rather than quiescent progenitors. Tuft cells are the only epithelial cells that express cyclooxygenase 2 (COX-2) in the normal intestinal epithelium. We previously generated Cdx2-transgenic mice as model mice for intestinal metaplasia and gastric carcinoma. In the current study, we investigated the association between COX-2 and DCAMKL1 in gastric carcinoma.

Methods

We examined the association between COX-2 and DCAMKL1 expression in gastric carcinomas in clinical samples (early gastric well-differentiated adenocarcinoma) and Cdx2-transgenic mice; and the DCAMKL1-transgenic mouse stomach using immunohistochemistry and quantitative real-time polymerase chain reaction.

Results

The COX-2-expressing cells were scattered, not diffusely expressed, in gastric carcinomas from humans and Cdx2-transgenic mice. DCAMKL1-positive cells were also scattered in the gastric carcinomas, indicating that tuft cells could still be present in gastric carcinoma. COX-2 was expressed in DCAMKL1-positive tuft cells in Cdx2- and DCAMKL1-transgenic mouse stomachs, whereas the Sox9 transcription factor was ubiquitously expressed in gastric carcinomas, including COX-2-positive cells.

Conclusions

COX-2 is expressed in DCAMKL1-expressing quiescent tuft cells in gastric carcinoma.

Antitumor effect of a selective COX-2 inhibitor, celecoxib, may be attributed to angiogenesis inhibition through modulating the PTEN/PI3K/Akt/HIF-1 pathway in an H₂₂ murine hepatocarcinoma model

Celecoxib, a selective cyclooxygenase-2 (COX-2) inhibitor, has recently been shown to affect the development of different types of cancer. The present study utilized a murine H22 hepatocarcinoma model to investigate the molecular mechanisms involved in celecoxib-induced inhibition of tumor angiogenesis. Tumor-bearing mice were randomly divided into five groups: i) control; ii) low-dose celecoxib (50 mg/kg); iii) high-dose celecoxib (200 mg/kg); iv) 5-fluorouracil (5-FU), (20 mg/kg) and v) combination of 5-FU and celecoxib (50 mg/kg). The antitumor effect of celecoxib was determined by measuring tumor volume. Tumor angiogenesis was evaluated by microvessel density (MVD). Tumor histology and immunostaining for CD34 in endothelial cells were performed to detect MVD. The expression levels of phosphatase and tensin homologue deleted from chromosome 10 (PTEN), phosphatidylinositol 3-kinase (PI3K), phospho‑Akt (P-Akt), COX-2, hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor-A (VEGF-A) were detected by ELISA, immunohistochemistry and western blotting, respectively. We discovered substantial growth delay in murine H22 hepatoma as a result of celecoxib treatment. The inhibition rate of tumor growth induced by high-dose and low-dose celecoxib was 49.3 and 37.0%, respectively (P<0.05). The expression of PI3K, P-Akt, COX-2, HIF-1α, VEGF-A and PTEN in tumor tissues treated with celecoxib was demonstrated by immunohistochemistry, and the MVD was decreased in a dose-dependent manner (P<0.05). Reduced PI3K and P-Akt was particularly apparent in the high-dose celecoxib group (P<0.05). ELISA and western blotting data showed that the expression of PI3K, P-Akt, COX-2, HIF-1α and VEGF-A were reduced and PTEN was increased after treatment with celecoxib. In conclusion, the impact of celecoxib-induced tumor growth delay of murine H22 hepatocarcinoma may correlate with the inhibition of angiogenesis by reducing PI3K, P-Akt, COX-2, HIF-1α and VEGF-A expression and increasing PTEN expression in tumor tissue.

Gefitinib and celecoxib in advanced metastatic gastrointestinal tumors: a pilot feasibility study

BACKGROUND

This pilot, open-label study examined the safety and tolerability (primary objective) and efficacy (secondary objective) of gefitinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, in combination with celecoxib, a cyclooxygenase-2 (COX-2) inhibitor, in patients with advanced or refractory gastrointestinal (GI) tumors of epithelial origin.

METHODS

Patients were administered gefitinib (250 mg/day) plus celecoxib (400 mg twice daily). In the event of toxicity, dose interruptions were permitted and a single celecoxib dose reduction was allowed.

RESULTS

Thirty patients (median age 60 years) with primary colorectal (25 patients), pancreatic (3 patients), esophageal (1 patient), or gall bladder (1 patient) tumors were recruited, 29 of whom had received prior chemotherapy. Adverse events (AEs) were generally mild and consisted mainly of acne, diarrhea, and nausea. Few severe AEs were noted. There were no withdrawals or deaths due to AEs. Dose reductions for celecoxib were reported for five patients, in three cases due to toxicity. Stable disease was confirmed in 12 patients (40%), with progressive disease in 18 patients (60%).

CONCLUSIONS

After study completion, safety issues relating to the long-term use of COX-2 inhibitors have been raised. However, in this pilot study, the combination of gefitinib and celecoxib was generally well tolerated in patients with advanced GI cancer.

Cyclooxygenase-2 expression is associated with poor overall survival of patients with gastric cancer: a meta-analysis

BACKGROUND

Cyclooxygenase-2 (COX-2) is believed to be involved in gastric carcinogenesis. However, it is still controversial whether COX-2 expression can be regarded as a prognostic factor for gastric cancer patients.

AIM

To obtain a more accurate relationship between COX-2 overexpression and prognosis in gastric cancer by meta-analysis.

METHOD

Relevant articles published up to May 2013 were searched by use of several keywords in electronic databases. Separate hazard ratio (HR) estimates and 95 % confidence intervals (95 % CI) for COX-2 overexpression and overall survival (OS) and disease-free survival (DFS) with gastric cancer were extracted. Combined HR with 95 % CI was calculated by use of Stata11.0 software to estimate the size of the effect. Publication bias testing and sensitivity analysis were also performed.

RESULTS

A total of 27 studies which included 3,891 gastric cancer patients were combined in the final analysis. Combined results suggested that COX-2 overexpression was associated with an unfavorable OS (HR 1.58, 95 % CI 1.36-1.84) but not DFS (HR 1.15, 95 % CI 0.93-1.43) among patients with gastric cancer. Publication bias was absent. Sensitivity analysis suggested that the results of this meta-analysis were robust.

CONCLUSIONS

The results of this meta-analysis suggest that high COX-2 expression may be an independent risk factor for poor OS of patients with gastric cancer. More large prospective studies are now needed to further clarify the prognostic value of COX-2 expression for DFS in gastric cancer.

Notch1 silencing inhibits proliferation and invasion in SGC‑7901 gastric cancer cells

Downregulation of Notch1 has been shown to exert antineoplastic effects in vivo and in vitro. However, the role of the Notch1 gene in the proliferative and invasive ability of gastric cancer cells is not clear. In this study, we investigated the effect of Notch1 gene silencing on the proliferation and invasion of gastric cancer SGC‑7901 cells. Small interfering RNA (siRNA) targeting Notch1 was transfected into SGC‑7901 cells using Lipofectamine 2000. Proliferation of SGC‑7901 cells was then determined by the MTT assay. Notch1 mRNA expression was determined by reverse transcription‑polymerase chain reaction (RT‑PCR). Invasion of the SGC‑7901 cells was detected by the Transwell assay. The protein levels of cyclin D1, cyclin A1 and cyclin-dependent kinase 2 (CDK2) were determined by western blotting. The mRNA levels of matrix metalloproteinase‑2 (MMP‑2) and cyclooxygenase‑2 (COX‑2) were determined by RT‑PCR. Compared to the control group, the Notch1 mRNA level was significantly decreased following transfection. The growth and invasion rates of SGC‑7901 cells were significantly reduced after Notch1 silencing. Additionally, the expression of cyclin D1 and cyclin A1 proteins and of the MMP‑2 and COX‑2 mRNAs was markedly attenuated. From these results, it was concluded that Notch1 gene silencing inhibits the proliferation of gastric SGC‑7901 cells by decreasing the expression of cyclins D1 and A1, and reduces the invasive ability of SGC‑7901 cells through the downregulation of MMP‑2 and COX‑2 genes. Thus, silencing of the Notch1 pathway may be a novel approach in the treatment of gastrointestinal cancer.

Association of COX2 gene hypomethylation with intestinal type gastric cancer in samples of patients from northern Brazil

To verify the methylation status of THBS1, GPX3, and COX2 genes and to evaluate their association with Helicobacter pylori in gastric adenocarcinomas. Methylation-sensitive restriction enzyme PCR assay was performed in 16 diffuse type gastric cancer samples, 23 intestinal type, and 15 normal stomach tissue. The presence of H. pylori was performed by amplification of the fragment of the 16S rRNA. Statistical analyses were performed using Fisher's exact test. The hypermethylation of GPX3, THBS1, and COX2 occurred in 18 (n = 7), 5 (n = 2), and 36 % (n = 14) of gastric cancer samples, respectively, whereas in normal samples, it was found in 13, 7, and 67 %. The presence of H. pylori was detected in 67 % of gastric cancer samples and 67 % in normal gastric samples. The methylation of THBS1 and GPX3 was not significantly different between the types of tumors, normal sample, the presence of H. pylori, or clinicopathological variables studied (P > 0.05). However, the methylation status of the gene COX2 is significantly different between normal tissue and intestinal type gastric cancer (P = 0.02). Therefore, our results suggest that the methylation status of the gene COX2 is associated with the intestinal type of gastric cancer.

Expression of COX-2 and E-cadherin in Tunisian patients with colorectal adenocarcinoma

Cyclo-oxygenase 2 (COX-2) and E-cadherin are promising biomarkers for cancer diagnosis and therapy. The aim of this study was to examine the expression of these two proteins in primary colorectal adenocarcinomas and to investigate their association with clinicopathological characteristics including survival of patients. Immunostaining of E-cadherin and COX-2 was assessed in 70 primary colorectal adenocarcinomas from Tunisian patients. Membranous E-cadherin immunostaining and cytoplasmic COX-2 expression were observed in 74.3% and 68.6% of cases respectively. A significant association was found between COX-2 expression and age at diagnosis (P=0.02), and vessel invasion (P=0.037). The expression of E-cadherin correlated with age at diagnosis (P=0.01), and tumor size (P=0.02). In addition, by multivariate analysis, we revealed a significant association with 1-year disease free survival and a tendency with distant metastasis (P=0.017 and P=0.065 respectively). On the other hand, tumors exhibiting COX-2+/E-cadherin-profile were larger (P=0.006), and in an advanced stage (P=0.001). Survival analysis showed that COX-2 over-expression confers a reduced overall survival rate (Plog rank=0.036) and is an independent factor predictive for prognosis.

Prognostic significance of vascular endothelial growth factor immunohistochemical expression in gastric cancer: a meta-analysis

Vascular endothelial growth factor (VEGF) is considered as a prime mediator of angiogenesis, and has been implicated in carcinogenesis and metastasis. Various studies examined the relationship between VEGF protein overexpression with the clinical outcome in patients with gastric cancer, but yielded conflicting results. The prognostic significance of VEGF overexpression in gastric cancer remains controversial. Electronic databases updated to July 2011 were searched to find relevant studies. A meta-analysis was conducted with eligible studies which quantitatively evaluated the relationship between VEGF overexpression and survival of patients with gastric cancer. Survival data were aggregated and quantitatively analyzed. We performed a meta-analysis of 30 studies (n = 3,999 patients) that evaluated the correlation between VEGF overexpression detected by immunohistochemistry and survival in patients with gastric cancer. Combined hazard ratios suggested that VEGF-A overexpression had an unfavorable impact on overall survival (OS) (HR [hazard ratio] = 1.49, 95 % CI [confidence interval]: 1.22-1.77) and disease free survival (DFS) (HR = 1.85, 95 % CI: 1.38-2.32) in patients with gastric cancer. However, VEGF-C overexpression did not significantly correlate with OS (HR = 1.24, 95 % CI: 0.92-1.56) or DFS (HR = 1.15, 95 % CI: 0.78-1.52). VEGF-D is an unfavorable indicator of OS (HR = 1.68, 95 % CI: 1.02-2.34) and DFS (HR = 1.88, 95 % CI: 1.07-2.70) in patients with gastric cancer. VEGF-A and VEGF-D overexpression indicated a poor prognosis for patients with gastric cancer. VEGF-C overexpression was not associated with poor prognosis in patients with gastric cancer. The prognostic value of VEGF on survival still needs further larger prospective trials to be confirmed.

Novel targeted agents for gastric cancer

Contemporary advancements have had little impact on the treatment of gastric cancer (GC), the world’s second highest cause of cancer death. Agents targeting human epidermal growth factor receptor mediated pathways have been a common topic of contemporary cancer research, including monoclonal antibodies (mAbs) and receptor tyrosine kinase inhibitors (TKIs). Trastuzumab is the first target agent evidencing improvements in overall survival in HER2-positive (human epidermal growth factor receptor 2) gastric cancer patients. Agents targeting vascular epithelial growth factor (VEGF), mammalian target of rapamycin (mTOR), and other biological pathways are also undergoing clinical trials, with some marginally positive results. Effective targeted therapy requires patient selection based on predictive molecular biomarkers. Most phase III clinical trials are carried out without patient selection; therefore, it is hard to achieve personalized treatment and to monitor patient outcome individually. The trend for future clinical trials requires patient selection methods based on current understanding of GC biology with the application of biomarkers.

Cyclooxygenase-2 and gastric cancer

Gastric cancer remains a leading cause of cancer-related deaths worldwide, although its incidence has been steadily declining during recent decades. Expression of cyclooxygenase-2 (COX-2) is elevated in gastric carcinomas and in their precursor lesions. COX-2 expression associates with reduced survival in gastric cancer patients, and it has also been shown to be an independent factor of poor prognosis. Several molecular mechanisms are involved in the regulation of COX-2 expression in gastric cancer cell lines, including signal transduction pathways activated by Helicobacter pylori. In gastric tumor models in vivo the role of COX-2 seems to be predominantly to facilitate tumor promotion and growth.

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.

Effects of macrophage metalloelastase on the basic fibroblast growth factor expression and tumor angiogenesis in murine colon cancer

BACKGROUND AND AIM

Previous studies have shown that overexpression of macrophage metalloelastase (MME) suppresses tumor growth in mice. The purpose of this study was to investigate the effects of MME on basic fibroblast growth factor (bFGF) expression and tumor angiogenesis in murine colon cancer.

METHODS

Murine CT-26 colon cancer cells stably transfected with MME were inoculated subcutaneously. Reverse-transcriptase polymerase chain reaction (RT-PCR), immunoblotting, and immunohistochemistry were used to explore the bFGF mRNA and protein expression. Immunohistochemical staining of CD34 was used to measure the microvessel density (MVD).

RESULTS

bFGF mRNA levels in tumor tissues of CT-26-EGFP and nontransfected cells were respectively 2.7-fold (0.56 ± 0.063 vs. 0.21 ± 0.042) and 2.5-fold (0.53 ± 0.066 vs. 0.21 ± 0.042) higher than that in tumors of CT-26-EGFP-MME cells (p < 0.01). bFGF protein levels exhibited a similar trend. Tumors of CT-26-EGFP-MME cells demonstrated a lower microvessel density (9.35 ± 2.79) than control tumors of CT-26-EGFP cells (22.85 ± 3.80) and nontransfected cells (23.45 ± 4.49) (p < 0.001).

CONCLUSIONS

We found that expression of MME inversely correlates with the expression of bFGF and tumor angiogenesis in a model of murine colon cancer. These data indicate that manipulation of MME expression could be a novel modality approach to colon cancer therapy.

Effects of cyclooxygenase-2 on human esophageal squamous cell carcinoma

AIM

To study the relationship between the cyclooxygenase (COX)-2 gene and the proliferation and apoptosis of esophageal squamous carcinoma EC109 cells.

METHODS

The techniques of RNA interference (RNAi) and cell transfection, as well as the levels of oncogenicity in nude mice, were used to study the role of COX-2 in the esophageal squamous carcinoma cell (ESCC) line EC109. Following RNAi and transfection, Western blotting analysis was used to determine the expression of the COX-2 protein. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) reduction assay was used to evaluate cell growth, and flow cytometry was used to detect cell apoptosis.

RESULTS

Western blotting analysis demonstrated that COX-2 expression was significantly reduced in EC109 cells treated with COX-2-specific short interfering RNA (siRNA) but was increased in EC109 cells transfected with COX-2. Furthermore, COX-2 siRNA treatment inhibited cell proliferation (P < 0.01) and induced apoptosis in EC109 cells, as determined by an MTT assay and by flow cytometry, respectively. In contrast, transfected COX-2 led to increased cell proliferation (P < 0.05) and decreased apoptosis in EC109 cells. In addition, combination treatment of cells with COX-2 siRNA and aspirin had a synergistic effect (P < 0.01). For experiments measuring tumorigenicity, xenograft tumors of a greater volume and weight were found in the COX-2 group compared with other groups (P < 0.05). A large dose of aspirin inhibited tumor growth in nude mice effectively (P < 0.05), and the rate of tumor suppression was 51.8% in the high-dose aspirin group.

CONCLUSION

COX-2 plays a very critical role in ESCC carcinogenesis, and COX-2 siRNA combined with aspirin has the potential to be an anticancer therapy for the treatment of ESCC.

Prognostic significance of cyclooxygenase-2, epidermal growth factor receptor 1, and microvascular density in gastric cancer

Gastric cancer remains a significant global health burden with poor treatment outcome. New treatment modalities that target inflammation, proliferation, and angiogenesis have been used in various cancers, including gastric cancer. We sought to study the pattern of expression of two important proteins, cyclooxygenase-2 and epidermal growth factor receptor, and their association with microvascular density, clinicopathological features, and survival in Arab Omani patients with gastric cancer. Formalin-fixed, paraffin-embedded tumors were studied by immunohistochemistry using monoclonal antibodies to cyclooxygenase-2, epidermal growth factor receptor, and CD34. The immunohistochemical results were correlated with clinicopathological features and survival. In our study population, we found a male/female ratio of 72:43, a median age of 59 years, stage III and IV incidence of 66.9%, and a median follow-up of 96 months. Positive expression rates of cyclooxygenase-2 and epidermal growth factor receptor were 89.6 and 23.5%, respectively. The median microvascular density value was 52.5. When this value was determined as the cut-off point, 50% of patients were found to have high microvascular density. Epidermal growth factor receptor over-expression correlated with high microvascular density values, advanced lymph node involvement (N3), and TNM stage presentation (III and IV). Similarly, lymph node involvement was associated with cyclooxygenase-2 over-expression and high microvascular density. Univariate analysis showed that epidermal growth factor receptor over-expression, pathological T3 and T4 disease, and overall stage III and IV disease were adverse prognostic factors. On multivariate analysis using a Cox regression model, expression of epidermal growth factor receptor, and advanced TNM stage were significant adverse prognostic factors for overall survival. Expression of epidermal growth factor receptor in Arab Omani patients with gastric cancer correlates with aggressive tumor characteristics and is an independent prognostic factor. Further clinical studies are needed to evaluate the utility of epidermal growth factor receptor immunohistochemistry as a tool for gastric cancer treatment.

Notch2-induced COX-2 expression enhancing gastric cancer progression

Gastric carcinoma is one of the most common and mortal types of malignancy worldwide. To date, the mechanisms controlling its aggressiveness are not yet fully understood. Notch signal pathway can function as either an oncogene or a tumor suppressor in tumorigenesis. Four members (Notch1-4) of Notch receptors were found in mammals and each exhibits distinct roles in tumor progression. Previous study showed that the activated Notch1 receptor promoted gastric cancer progression through cyclooxygenase-2 (COX-2). This study addressed whether Notch2 signal pathway is also involved in gastric cancer progression. Constitutive expression of Notch2 intracellular domain (N2IC), the activated form of Notch2 receptor, promoted both cell proliferation and xenografted tumor growth of human stomach adenocarcinoma SC-M1 cells. The colony formation, migration, invasion, and wound-healing abilities of SC-M1 cells were enhanced by N2IC expression, whereas these abilities were suppressed by Notch2 knockdown. Similarly, Notch2 knockdown inhibited cancer progressions of AGS and AZ521 gastric cancer cells. Expression of N2IC also caused epithelial-mesenchymal transition in SC-M1 cells. Furthermore, N2IC bound to COX-2 promoter and induced COX-2 expression through a CBF1-dependent manner in SC-M1 cells. The ability of N2IC to enhance tumor progression in SC-M1 cells was suppressed by knockdown of COX-2 or treatment with NS-398, a COX-2 inhibitor. Moreover, the suppression of tumor progression by Notch2 knockdown in SC-M1 cells was reversed by exogenous COX-2 or its major enzymatic product PGE(2) . Taken together, this study is the first to demonstrate that the Notch2-COX-2 signaling axis plays an important role in controlling gastric cancer progression.

Prognostic significance of vascular endothelial growth factor expression in gastric carcinoma: a meta-analysis

PURPOSE

The purpose of this study was to comprehensively and quantitatively summarize available evidences for the use of VEGF protein to evaluate the clinicopathological and prognostic role of VEGF expression in Asian patients with gastric cancer.

METHOD

Searches were applied to MEDLINE, EMBASE, and the Cochrane Library databases until June 2010, without language restrictions. A meta-analysis was performed to clarify the impact of VEGF expression on clinicopathological parameters or over survival (OS) in gastric cancer.

RESULTS

Our combined results showed that VEGF expression in Asian patients with gastric cancer was significantly higher in the case-control studies (1,194 patients and 1,618 controls) (odds ratio [OR] = 112.41, 95% confidence interval [CI] = 64.12-197.06). All the analyses estimated favored a stronger link between the high VEGF expression and the poor 5-year overall survival (1,236 patients) (risk ratio [RR] = 2.45, 95% CI = 2.11-2.83, P = 0.000). When stratifying the studies by the pathological variables, the depth of invasion (3,094 patients) (OR = 1.95, 95% CI = 1.40-2.71, P = 0.000), lymph node metastasis (3,240 patients) (OR = 1.82, 95% CI = 1.29-2.57, P = 0.001), distant metastasis (1,980 patients) (OR = 2.76, 95% CI = 1.22-6.25, P = 0.015), vascular invasion (1,803 patients) (OR = 2.61, 95% CI = 2.09-3.27, P = 0.000), and TNM stage (1,819 patients) (OR = 1.92, 95% CI = 1.57-2.36, P = 0.000) provided significant prognostic information.

CONCLUSION

Our results indicate that VEGF can potently predict the overall survival in Asian patients with gastric cancer. Importantly, VEGF may be converted from candidate to the routine clinical setting for clinicians to predict the outcome of single patient with gastric carcinoma.

Genomic and genetic alterations influence the progression of gastric cancer

Gastric cancer is one of the leading causes of cancer-related deaths worldwide, although the incidence has gradually decreased in many Western countries. Two main gastric cancer histotypes, intestinal and diffuse, are recognised. Although most of the described genetic alterations have been observed in both types, different genetic pathways have been hypothesized. Genetic and epigenetic events, including 1q loss of heterozygosity (LOH), microsatellite instability and hypermethylation, have mostly been reported in intestinal-type gastric carcinoma and its precursor lesions, whereas 17p LOH, mutation or loss of E-cadherin are more often implicated in the development of diffuse-type gastric cancer. In this review, we summarize the sometimes contradictory findings regarding those markers which influence the progression of gastric adenocarcinoma.

Prognostic significance of serum vascular endothelial growth factor per platelet count in unresectable advanced gastric cancer patients

OBJECTIVE

Angiogenesis is one of the crucial steps in various solid tumor growth and metastasis. However, there are limited data regarding the clinical and prognostic significance of serum vascular endothelial growth factor levels per platelet count in unresectable advanced gastric cancer compared with early gastric cancer and healthy volunteers.

METHODS

A total of 181 gastric cancer patients were included and control serum samples were acquired from 113 healthy volunteers. The levels of serum vascular endothelial growth factor were measured using human vascular endothelial growth factor quantitative enzyme-linked immunosorbent assay. Survival curves were calculated using the Kaplan-Meier method and survival comparisons were made by the log-rank test in metastatic gastric cancer.

RESULTS

There was a significant correlation between serum vascular endothelial growth factor levels and differentiation of tumor (P = 0.014), stage (P = 0.036). The overall survival (P = 0.0432) and the progression-free survival (P = 0.0116) were significantly shorter in patients with high serum vascular endothelial growth factor per platelet count (≥1.626 pg/10(6)). In the multivariate analysis, the presence of peritoneal carcinomatosis (P = 0.039), serum vascular endothelial growth factor per platelet (P = 0.005) were found to be significantly associated with poor progression-free survival.

CONCLUSIONS

This study demonstrates that serum vascular endothelial growth factor per platelet count is correlated with poor overall survival and progression-free survival in patients with advanced gastric cancer.

Vascular endothelial growth factor and not cyclooxygenase 2 promotes endothelial cell viability in the pancreatic tumor microenvironment

OBJECTIVES

Cyclooxygenase 2 (COX-2) and vascular endothelial growth factor (VEGF), often coexpressed in cancer, are associated with poor prognosis. However, results from pancreatic cancer trials of their inhibitors were disappointing. This study delineated the role of COX-2 and nonsteroidal anti-inflammatory drugs in angiogenesis and VEGF regulation.

METHODS

AsPC-1 and BxPC-3 pancreatic cancer cells were cocultured with human umbilical vein endothelial cells (HUVECs). NS398 or VEGF-neutralizing antibody was added, and HUVEC viability assayed. Prostaglandin E2 and VEGF were quantified. Tumor cells were treated with NS398 or celecoxib, and VEGF quantified.

RESULTS

In cocultures, HUVEC viability in AsPC-1 was 60% that of BxPC-3 controls (P < 0.05). Prostaglandin E2 and VEGF from BxPC-3 were double that of AsPC-1 (P < 0.05). NS398 reduced prostaglandin E2 to undetectable levels (P < 0.05) but had no effect on HUVEC viability. Vascular endothelial growth factor-neutralizing antibody reduced HUVEC viability in BxPC-3 wells to that of AsPC-1 (P < 0.05). NS398 had no effect on VEGF. Celecoxib increased VEGF in a concentration-dependent manner in each cell line up to 4-fold (P < 0.05).

CONCLUSIONS

Cyclooxygenase 2 does not regulate VEGF in pancreatic cancer, and celecoxib upregulates VEGF in pancreatic cancer. It is VEGF, and not COX-2, inhibitors that reduce tumor-stimulated endothelial cell viability. Future pancreatic cancer trials should consider lower-dose nonsteroidal anti-inflammatory drugs in combination with VEGF inhibitors.

Comparative analysis of clinicopathological correlations of cyclooxygenase-2 expression in resectable pancreatic cancer

AIM: To perform a comparative analysis of clinicopathological correlations of cyclooxygenase-2 (COX-2) expression in pancreatic cancer, examined by monoclonal and polyclonal antibodies.

METHODS: The COX-2 expression in 85 resection specimens of pancreatic ductal adenocarcinoma was immunohistochemically examined using both monoclonal and polyclonal antibodies. The final immunoscores were obtained by multiplying the percentage of positive cells with the numeric score reflecting the staining intensity. COX-2 expression levels were classified into three categories (0, 1+, and 2+) and the clinicopathological correlations were statistically evaluated and analyzed.

RESULTS: The positive tumor expression rates of COX-2 were 80.5% using monoclonal antibody and 69.4% using polyclonal antibody. In the Kaplan-Meier analysis, no significant correlations were found between levels of COX-2 expression and overall survival (OS), but trends to longer OS were found in COX-2 negative cases using monoclonal antibody. Significantly longer disease free survival was revealed in COX-2 negative cases using monoclonal antibody (P = 0.019). No correlations between COX-2 expression levels and grade (G), tumor (T) status and nodal (N) status were demonstrated. Low histological grade showed a strong association with a longer OS (P < 0.001). Correlation of survival and T status revealed a shorter OS in T3 tumors, but the results reached only marginal statistical significance (P = 0.070). In the multivariate Cox proportional hazards regression model, histological grade, T and N status remained valuable predictors of a worse survival with borderline significance for T [hazards ratio (HR) = 4.18 for G (if G = 3, P < 0.001); HR = 1.64 for T (if T = 3, P = 0.065); HR = 2.53 for N (if N = 1, P = 0.006)]. Higher grade, T or N status was associated with a worse OS.

CONCLUSION: The immunohistochemically assessed level of COX-2 expression does not seem to represent a valuable independent prognostic factor and is not superior to the conventional prognostic factors.

Clinical significance of Cox-2, Survivin and Bcl-2 expression in hepatocellular carcinoma (HCC)

Cox-2, Survivin and Bcl-2 are frequently overexpressed in numerous types of cancers. They are known to be the important regulators of apoptosis. This study was designed to investigate the correlation between the clinical characteristics and the expression of Cox-2, Survivin and Bcl-2 in hepatocellular carcinoma. A total of 63 postoperative hepatocellular carcinoma (HCC) samples, 10 adjacent non-tumor samples and 10 normal liver samples were immunochemically detected for the expression of Cox-2, Survivin and Bcl-2. A median follow-up of 4 years for the 63 HCC patients was conducted. Univariate tests and multivariate Cox regression were performed for statistical analysis. The Kaplan-Meier method was used to analyze the survival. Positive expression of Cox-2 (84.3%) and Survivin (77.8%) was detected significantly more frequently in the HCC samples than in the normal liver tissues (30% and 0, respectively). Bcl-2 was highly expressed in the adjacent non-tumor tissue. Cox-2 was positively correlative to Survivin. Survivin and Bcl-2 were significantly associated with the pathological grade of HCC (P<0.05). Expression of both Cox-2 and Survivin was significantly associated with the poor overall survival (OS) (P=0.0141, P=0.0039). Furthermore, multivariate analysis confirmed the independent prognostic value of Survivin expression, along with tumor size and hepatic function. Cox-2 and Survivin were highly expressed in the HCC tissue. Survivin and Bcl-2 were significantly associated with the pathological grade of HCC. The expression of Survivin was an independent prognostic factor for HCC after a hepatectomy. Treatment that inhibits Survivin may be a promising targeted approach in HCC.

MBP-1 suppresses growth and metastasis of gastric cancer cells through COX-2

The c-Myc promoter binding protein 1 (MBP-1) is a transcriptional suppressor of c-myc expression and involved in control of tumorigenesis. Gastric cancer is one of the most frequent neoplasms and lethal malignancies worldwide. So far, the regulatory mechanism of its aggressiveness has not been clearly characterized. Here we studied roles of MBP-1 in gastric cancer progression. We found that cell proliferation was inhibited by MBP-1 overexpression in human stomach adenocarcinoma SC-M1 cells. Colony formation, migration, and invasion abilities of SC-M1 cells were suppressed by MBP-1 overexpression but promoted by MBP-1 knockdown. Furthermore, the xenografted tumor growth of SC-M1 cells was suppressed by MBP-1 overexpression. Metastasis in lungs of mice was inhibited by MBP-1 after tail vein injection with SC-M1 cells. MBP-1 also suppressed epithelial-mesenchymal transition in SC-M1 cells. Additionally, MBP-1 bound on cyclooxygenase 2 (COX-2) promoter and downregulated COX-2 expression. The MBP-1-suppressed tumor progression in SC-M1 cells were through inhibition of COX-2 expression. MBP-1 also exerted a suppressive effect on tumor progression of other gastric cancer cells such as AGS and NUGC-3 cells. Taken together, these results suggest that MBP-1-suppressed COX-2 expression plays an important role in the inhibition of growth and progression of gastric cancer.

Chemoprevention by celecoxib in reflux-induced gastric adenocarcinoma in Wistar rats that underwent gastrojejunostomy

PURPOSE

To evaluate chemoprevention by celecoxib in cases of reflux-induced gastric adenocarcinoma, in Wistar rats that underwent gastrojejunostomy.

METHODS

Sixty male Wistar rats of average age three months underwent surgery and were distributed into three groups: group 1, exploratory laparotomy; group 2, gastrojejunostomy; and group 3, gastrojejunostomy and daily celecoxib administration. After 53 weeks, the animals were sacrificed. Changes in the mucosa of the gastric body of group 1 and in the gastrojejunal anastomosis of groups 2 and 3, observed in histopathological and immunohistochemical examinations, were compared. All statistical analyses were performed using Epi-Info, version 3.4.3.

RESULTS

Comparison between groups 2 and 3 relative to the presence of adenocarcinoma showed a statistically significant difference (p=0.0023). Analysis of the association between groups 2 and 3 relative to COX-2 expression also showed a statistically significant difference (p=0.0018).

CONCLUSION

Celecoxib had an inhibiting effect on gastric carcinogenesis induced by enterogastric reflux in an animal model.

COX-2, VEGF and tumour angiogenesis

Epidemiological evidence suggests a protective effective of regular NSAID use against developing cancer. Cyclooxygenase-2, a target of NSAIDs, is upregulated in many cancers and has been associated with increased VEGF production and angiogenesis. Angiogenesis is the formation of new vessels from existing vasculature and as an essential process for tumour development represents an important therapeutic target. Following an extensive review of the literature this article details the current knowledge on the role of COX-2 in tumorigenesis focusing on its relationship to angiogenesis and VEGF production by tumour cells. While COX-2 is clearly detrimental to prognosis and NSAIDs have a beneficial effect, the possibility of COX-2 independent effects being partly or wholly responsible for this benefit cannot be excluded.

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.

The activated Notch1 signal pathway is associated with gastric cancer progression through cyclooxygenase-2

Gastric carcinoma is one of the most common cancers and lethal malignancies worldwide. Thus far, the regulatory mechanisms of its aggressiveness are still poorly understood. To understand the pathogenesis and to develop new therapeutic strategies, it is essential to dissect the molecular mechanisms that regulate progression of gastric cancer. Herein, we sought to address whether Notch1 signal pathway is involved in the control of progression in gastric cancer. We found that expression of Notch ligand Jagged1 was correlated with aggressiveness of human gastric cancer. Patients with Jagged1 expression in gastric cancer tissues had a poor survival rate compared with those without Jagged1 expression. The Notch1 receptor intracellular domain (N1IC), the activated form of Notch1 receptor, promoted the colony-forming ability and xenografted tumor growth of human stomach adenocarcinoma SC-M1 cells. Migration and invasion abilities of SC-M1 cells were enhanced by N1IC. Furthermore, N1IC and C promoter-binding factor 1 (CBF1) bound to cyclooxygenase-2 (COX-2) promoter and elevated COX-2 expression in SC-M1 cells through a CBF1-dependent manner. The colony-forming, migration, and invasion abilities enhanced by N1IC were suppressed in SC-M1 cells after treatment with the COX-2 inhibitor NS-398 or knockdown of COX-2. These cellular processes inhibited by Notch1 knockdown were restored by prostaglandin E(2) or exogenous COX-2. Taken together, these results suggest that activation of Notch1 signal pathway promotes progression of gastric cancer, at least in part through COX-2.

Overexpression of phosphorylated mammalian target of rapamycin predicts lymph node metastasis and prognosis of chinese patients with gastric cancer

PURPOSE

We determined the expression of mammalian target of rapamycin (mTOR) and its activated form, p-mTOR, in Chinese patients with gastric cancer and its clinical effects and underlying mechanisms.

EXPERIMENTAL DESIGN

Tissue microarray blocks containing gastric cancer tissue and matched noncancer gastric tissue specimens obtained from 1,072 patients were constructed. Expression of total mTOR and p-mTOR in these specimens was analyzed using immunohistochemical studies and confirmed by Western blotting.

RESULTS

The overall rates of total mTOR and p-mTOR overexpression were 50.8% (545 of 1,072) and 46.5% (499 of 1,072), respectively. The p-mTOR overexpression was significantly correlated with total mTOR overexpression. Overexpression of total mTOR protein was significantly correlated with tumor differentiation, T1/T2 tumors, and stage I/II/III disease, whereas p-mTOR overexpression was significantly correlated with lymph node metastasis and all stage disease. The Cox proportional hazards model revealed that the overexpression of p-mTOR, but not total mTOR, was an independent prognostic factor for gastric cancer. The overexpression of p-mTOR also predicted the angiogenic phenotype of human gastric cancer and regulated angiogenesis of gastric cancer cells.

CONCLUSIONS

Increased activation of mTOR is frequent in human gastric cancer and overexpression of p-mTOR is an independent prognostic factor, suggesting that mTOR pathway could be a potential target for therapy of this malignancy.

Cyclooxygenase-2 expression: does it have a probable role in tumorigenesis mechanisms of renal cell carcinoma?

OBJECTIVES

The purpose of this study was to evaluate the correlation between the levels of cyclooxygenase-2 (COX-2) expression with clinicopathologic features and determine the impact on prognosis in patients with renal cell carcinoma (RCC).

METHODS

Expression of COX-2 was evaluated immunohistochemically in RCC tissues from 62 patients who underwent radical nephrectomy between 1996 and 2004. Percentage of COX-2 staining was scored as 0 (negative), 1 (1-24%), 2 (25-49%), 3 (50-74%), and 4 (75-100%). Immunohistochemical COX-2 staining score (ISS) was defined as summation of intensity and percentage of COX-2 staining.

RESULTS

Twenty-seven patients (43.5%) with a median follow-up of 47.8 (25-115) months stained positively for COX-2. COX-2 expression was positive in 37.1%, 50%, and 66.7% of patients with stages 1, 2, and 3, respectively (P = 0.46). Correlation between ISS and pathological stage was statistically significant (P = 0.005). Multivariate regression analysis revealed no clinicopathologic parameter as independent predictors of progression. Kaplan-Meier analysis revealed statistically significant different survival rates in tumor stage, grade, and ISS.

CONCLUSION

Although COX-2 expression is not an independent predictor of progression in patients with RCC, patients with higher ISS values have significantly shorter progression-free survival rates. These results might be important to the clinician because positive COX-2 expression of a certain RCC might necessitate early adjuvant systemic therapy to delay the progression of RCC. For this reason, there is a need for innovative, prospective, and randomized studies in patients with positive COX-2 expression that will display the impact of systemic therapies in these patients.

Lactobacillus acidophilus 74-2 and butyrate induce cyclooxygenase (COX)-1 expression in gastric cancer cells

Cyclo-oxygenase (COX) profile predicts prognosis of gastric cancer; COX-2 positive tumors are more often aggressive, and COX-2 suppression is protective against gastric cancer. In contrast, COX-1 suppression is harmful to the intestinal mucosa. The COX-1, COX-2, and COX-1ir expression profiles were measured with real-time PCR in primary (AGS) and metastatic (NCI-N87) gastric adenocarcinoma cell lines treated with butyrate, hyperosmolar medium, and, in the case of NCI-N87, cell-free supernatants of probiotic bacteria Lactobacillus acidophilus 74-2 and Bifidobacterium lactis 420. The cell lines showed differences in the profile when treated with either hyperosmolar medium or butyrate. In NCI-N87 COX-2 expression was higher but only COX-1 expression was significantly upregulated by butyrate. Similarly to butyrate, the cell-free supernatant of L. acidophilus 74-2 upregulated COX-1, while COX-2 expression remained unchanged. COX-1ir, including COX-3, was upregulated by probiotics and osmotic stress. In conclusion, consumption of L. acidophilus 74-2 could be beneficial for the expression of cytoprotective COX-1.

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.

Vascular endothelial growth factor, hypoxia-inducible factor 1 alpha and CD34 expressions in early-stage gastric tumors: relationship with pathological factors and prognostic impact on survival

BACKGROUND

Angiogenesis is one of the key steps in solid tumor growth and metastasis. We planned to investigate the prognostic significance of vascular endothelial growth factor (VEGF), hypoxia-inducible factor 1alpha (HIF-1alpha) and CD34 expressions as markers of angiogenesis in gastric cancer.

PATIENTS AND METHODS

We retrospectively reviewed the medical records of 51 gastric cancer patients who had total or subtotal gastrectomy at Marmara University Hospital from 1990 to 2004 and evaluated the expression of VEGF, HIF-1alpha and CD34 by immunohistochemistry in their archival tumor tissues. We recorded the clinical and pathological characteristics of these patients and analyzed their survival outcome.

RESULTS

Thirty out of 51 patients were males. The median age was 63 years (range 34-81). The median follow-up was 17 months. Thirty-six patients had node-positive disease. The majority of patients (n = 43) had T2 and T3 disease. Vascular and lymphatic invasions were present in 57 and 77% of tumors, respectively. VEGF and HIF-1alpha were positive in 65 and 71% of tumors. The median CD34 staining score was 19 (3-68). VEGF, HIF-1alpha and CD34 expressions were more frequent in tumors without serosal invasion (p = 0.01, p = 0.01 and p = 0.003, respectively). CD34 expression was significantly more frequent in tumors with VEGF and HIF-1alpha expression (p = 0.00, p = 0.00). HIF-1alpha expression was more frequent in tumors with VEGF expression (p = 0.00). The 5-year overall survival was 45%. VEGF, HIF-1alpha, CD34 expressions and other pathological characteristics were found to have no impact on survival.

CONCLUSION

VEGF, HIF-1alpha and CD34 expressions were more common in tumors without serosal invasion. As a future perspective, biological agents targeting VEGF and HIF-1alpha might be more effective at earlier stages of gastric cancer.

mRNA stability and cancer: an emerging link?

Many oncogenes, growth factor, cytokine and cell-cycle genes are regulated post-transcriptionally. The major mechanism is by controlling the rate of mRNA turnover for transcripts bearing destabilizing cis-elements. To date, only a handful of regulatory factors have been identified that appear to control a large pool of target mRNAs, suggesting that a slight perturbation in the control mechanism may generate wide-ranging effects that could contribute to the development of a complex disorder such as cancer. In support of this view, mRNA turnover responds to signalling pathways that are often overactive in cancer, suggesting a post-transcriptional component in addition to the well-recognised transcriptional aspect of oncogenesis. Here the authors review examples of deregulated post-transcriptional control in oncogenesis, discuss post-transcriptionally regulated transcripts of oncologic significance, and consider the key role of signalling pathways in linking both processes and as an enticing therapeutic prospect.

Cyclooxygenase in the treatment of glioma: its complex role in signal transduction

BACKGROUND

High-grade glioma remains one of the most difficult cancers to treat. Recent studies in oncology have identified a role of the ubiquitous enzyme, cyclooxygenase (Cox), especially cyclooxygenase-2 (COX-2) in cell proliferation, and its inhibition in cancer control, apoptosis, as well as synergy with other forms of therapy. The inhibitors of the Cox enzyme are well known as members of the nonsteroidal anti-inflammatory drug (NSAID) class of pharmaceuticals.

METHODS

In vitro and in vivo studies of different cancers expressing COX-2, including glioma studies, along with the few clinical trials that have been reported are reviewed to specifically identify the actions of these agents.

RESULTS

The anticancer effect of the COX-2 inhibitors may occur irrelevant of COX-2 expression, and it appears to be drug-specific, as well as dose-specific in different cancers. In combination with chemotherapeutic agents, the COX-2 inhibitors may have an additive, synergistic, or inhibitory effect on tumor growth.

CONCLUSIONS

As evaluations of this class of drugs begin in glioma, in vitro and in vivo data should be acquired to accurately predict which compounds will have an effect in controlling tumor growth and at which doses these should be used. The actual expression and inhibition of COX-2 may not always be relevant to the effects on tumor growth.