Cyclooxygenase-2 expression is associated with VEGF-C and lymph node metastases in gastric cancer patients

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.

Augmented Activity of Cyclooxygenase-2 in Tissue and Serum of Patients With Cervical Cancer

BACKGROUND

Cyclooxygenase-2 (Cox-2) is frequently overexpressed in cervical carcinoma, but little is known about its altered serum concentration. Hence, this study evaluates clinical utility of cellular and serum level of Cox-2 enzyme in cervical cancer.

METHODS

The expression of Cox-2 was evaluated in cervical tissues and serum samples collected from normal controls (n = 100; n = 68), cervical intraepithelial neoplasia patients (CIN, n = 67; n = 12), and invasive squamous cell carcinoma patients (SCCs; n = 153; n = 127) by immunohistochemical and enzyme-linked immunosorbent assay (ELISA) analyses.

RESULTS

The significant cytoplasmic overexpression of Cox-2 was noted in 50.7% of CIN and 69.9% of SCCs as compared with normal (P = 0.0001). Serum level of Cox-2 was also found to be elevated both in CIN (median 4.35 ng/ml) and in SCCs (median 19.39 ng/ml) with respect to normal (median 0.44 ng/ml; P = 0.0001), respectively. The ROC analysis revealed the potential of serum Cox-2 over its cellular expression to distinguish CIN and SCCs from normal.

CONCLUSION

Augmented Cox-2 activity is implicated in the pathogenesis of cervical cancer, and its serum level could serve a potential to distinguish this malignancy. Therefore, it is suggested that serum Cox-2 may be useful in monitoring the diagnosis and treatment outcome of patients.

Survivin gene expression increases gastric cancer cell lymphatic metastasis by upregulating vascular endothelial growth factor-C expression levels

The aim of this study was to investigate the correlation between the expression of survivin and vascular endothelial growth factor‑C (VEGF‑C) in gastric cancer and the pathway by which survivin may affect gastric cancer lymphatic metastasis. The study may provide novel targets for treating gastric cancer lymphatic metastasis and distal dissemination. Survivin and VEGF‑C expression in gastric carcinoma and peri‑carcinoma (2 cm away from the carcinoma) tissues, obtained from 195 patients who underwent curative gastrectomy surgery (130 cases presented with lymph node metastasis and 65 cases presented without metastasis), was examined immunohistochemically using a tissue microarray. Plasmids containing survivin and VEGF‑C shRNA were constructed and transfected into SGC‑7901 gastric cancer cells. The expression levels of the two genes were examined using western blot analysis and qPCR, and the results were statistically analyzed. The expression levels of survivin and VEGF‑C were 51.3 and 55.4%, respectively, in gastric carcinoma. Survivin and VEGF‑C were located mainly in the cytoplasm of the tumor cells. The expression levels of survivin and VEGF‑C were significantly higher in patients with lymph node metastasis than in those without metastasis (P=0.008 and 0.001, respectively). Patients with high expression levels of survivin and VEGF‑C showed significantly less favorable survival rates compared with patients with low expression levels of those two genes (P=0.003 and 0.039, respectively). Moreover, patients with co‑expression of the two genes usually had a poorer prognosis (P=0.003). However, multivariate analysis demonstrated that neither of the two genes were an independent prognostic determinant. The levels of VEGF‑C expression may be regulated by survivin expression. Conversely, inhibiting VEGF‑C gene expression by shRNA did not reduce survivin expression at the mRNA or protein levels. Survivin and VEGF‑C were expressed in gastric cancer cells and were significantly associated with lymphatic metastasis. Survivin may be a regulator of VEGF‑C expression in gastric cancer cells, and is essential in invasion and lymphatic metastasis. Moreover, survivin may be able to serve as a chemotherapy target for gastric cancer.

Lymphovascular and neural regulation of metastasis: shared tumour signalling pathways and novel therapeutic approaches

The progression of cancer is supported by a wide variety of non-neoplastic cell types which make up the tumour stroma, including immune cells, endothelial cells, cancer-associated fibroblasts and nerve fibres. These host cells contribute molecular signals that enhance primary tumour growth and provide physical avenues for metastatic dissemination. This article provides an overview of the role of blood vessels, lymphatic vessels and nerve fibres in the tumour microenvironment and highlights the interconnected molecular signalling pathways that control their development and activation in cancer. Further, this article highlights the known pharmacological agents which target these pathways and discusses the potential therapeutic uses of drugs that target angiogenesis, lymphangiogenesis and stress-response pathways in the different stages of cancer care.

Impact of acetylsalicylic acid on tumor angiogenesis and lymphangiogenesis through inhibition of VEGF signaling in a murine sarcoma model

Aspirin is a salicylate drug that is widely used, and recently it has been shown to influence the development of various types of cancers. Our previous study revealed that aspirin had an inhibitory effect on the growth of S180 sarcoma and 3AO human ovarian cancer cells. The present study utilized a murine S180 sarcoma model to investigate the molecular mechanisms involved in aspirin-induced tumor growth inhibition. Tumor-bearing mice were randomly divided into five groups with 10 mice in each group: i) control; ii) 5-fluorouracil (5-FU); iii) high-dose aspirin (250 mg/kg); iv) low-dose aspirin (50 mg/kg); and v) combination of 5-FU and aspirin (50 mg/kg). The effect of aspirin on tumor growth was observed by measuring tumor volume and evaluating the antitumor effect. Tumor histology and immunohistochemistry were performed to detect the microvessel density (MVD), lymphatic vessel density (LVD), and the expression levels of vascular endothelial growth factor A (VEGF-A) and VEGF-C. The expression of VEGF-A and VEGF-C was also confirmed and quantified by western blotting. We discovered significant growth delay in murine S180 sarcoma as a result of aspirin treatment. The inhibition rate of tumor growth induced by high-dose and low-dose aspirin was 33.5 and 22.2%, respectively (P<0.05). The expression of VEGF-A and VEGF-C in tumor tissues inhibited by aspirin was demonstrated by immunohistochemistry, and the MVD was decreased in a dose-dependent manner (p<0.05). Reduced LVD was particularly apparent in the high-dose aspirin group (p<0.05). Western blot data showed that the expression of both VEGF-A and VEGF-C was reduced after treatment with aspirin. In conclusion, the impact of aspirin-induced tumor growth delay of murine S180 sarcoma may correlate with the inhibition of angiogenesis and lymphangiogenesis by reducing VEGF-A and VEGF-C expression in tumor tissues.

The microRNA-27a: ZBTB10-specificity protein pathway is involved in follicle stimulating hormone-induced VEGF, Cox2 and survivin expression in ovarian epithelial cancer cells

Previously, we demonstrated that follicle stimulating hormone (FSH) enhanced VEGF expression and facilitated ovarian cancer angiogenesis via the PI3K/AKT signaling pathway. In this study, we further investigated the involvement of microRNA-27a: ZBTB10‑specificity protein pathway in the mechanism of FSH-induced VEGF, Cox2 and survivin expression. Treatment with FSH resulted in significant increase in the expression of VEGF, Cox2, survivin, Sp1 proteins and microRNA-27a in a dose-dependent manner, whereas reverse protein expression pattern was observed in ZBTB10. Downregulation of microRNA-27a using antisense microRNA-27a blocked FSH-induced VEGF, Cox2 and survivin expression. Overexpression of ZBTB10 also attenuated the FSH-induced expression of these molecules. The enhanced expression of VEGF, Cox2 and survivin was also abolished by knocking down Sp1 using small interfering RNA. Collectively, these results indicated that stimulation of ovarian cancer cell VEGF, Cox2 and survivin expression by FSH involves the microRNA‑27a: ZBTB10-specificity protein pathway.

Lymphangiogenesis in non-Hodgkin's lymphoma and its correlation with cyclooxygenase-2 and vascular endothelial growth factor-C

We aimed to investigate the correlations between lymphangiogenesis, cyclooxygenase (COX)-2 and vascular endothelial growth factor-C (VEGF-C) in non-Hodgkin's lymphoma (NHL) and their associations with the clinical parameters of patients. A total of 75 patients diagnosed with NHL were enrolled in this study. Of the 75 patients, 14 (18.7%) had low-grade and 61 (81.3%) had aggressive lymphoma. We examined the immunohistochemical expression of COX-2 and VEGF-C and estimated lymphangiogenesis by counting lymphatic vessels expressing lymph vessel endothelial hyaluronan receptor-1 (LYVE-1). Our results showed that lymphatic vessel density (LVD) was positive in 59.0% of the cases with aggressive morphology, while the LVD positive rate of indolent lymphoma was only 28.6% (P=0.039). Both COX-2 and VEGF-C were correlated with lymphangiogenesis (P=0.030 and 0.000, respectively). The expression levels of COX-2 and VEGF-C were significantly correlated (P=0.015). LVD, COX-2 and VEGF-C were not correlated with the gender, age, lactate dehydrogenase (LDH) levels, β2 microglobulin (β2M) levels, extranodal involvement, disease stage, B symptoms or international prognostic index of the patients. In conclusion, lymphangiogenesis was correlated with aggressive histology in NHL. COX-2 and VEGF-C are inducers of lymphangiogenesis and their expression levels were correlated in NHL.

Involvement of nuclear factor κB (NF-κB) in the downregulation of cyclooxygenase-2 (COX-2) by genistein in gastric cancer cells

Genistein induces growth inhibition in various human cancer cell lines but its mechanism of action remains unknown. This study determined whether the effect of genistein is mediated via suppression of cyclo-oxygenase (COX)-2 protein, and elucidated the mechanism of action of this effect in the human gastric cancer cell line BGC-823. Genistein treatment inhibited cell proliferation and induced apoptosis in a dose- and time-dependent manner; Western blotting analysis indicated a significant dose-dependent decrease in COX-2 protein levels. Genistein treatment exerted a significant inhibitory effect on activation of the transcription factor nuclear factor κB (NF-κB). Additionally, the NF-κB inhibitor pyrrolidine dithiocarbamate caused a reduction in COX-2 protein levels and NF-κB activation, similar to the effect of genistein. Suppression of COX-2 protein may be important for the antiproliferative and proapoptotic effects of genistein in BGC-823 cells, and these effects may be partly mediated through the NF-κB pathway.

Modulation of lymphangiogenesis: a new target for aspirin and other nonsteroidal anti-inflammatory agents? A systematic review

Recent studies have implicated that lymphangiogenesis plays a role in the development of metastasis in experimental cancer models and in certain types of human tumors. Epidemiological and laboratory data suggest that non steroidal anti-inflammatory agents (NSAIDs) have antitumor activities, although the mechanisms have not been elucidated. This systematic review aimed to synthesize data on the effect of aspirin and other NSAIDs on lymphangiogenesis. In particular, an answer was attempted to be found for the following primary questions: Is there an effect of aspirin and NSAIDs on lymphangiogenesis? If yes, is this effect mediated through COX-II inhibition or through COX-II-independent mechanisms? Electronical databases were searched with the appropriate search terms for the period from 1966 up to and including February 2011. The few identified experimental trials indicated that aspirin and other NSAIDs inhibit lymphangiogenesis, with a potential decrease in metastatic spread, possibly through COX-II-dependent regulation of VEGF-C expression. COX-II-independent mechanisms of inhibition of lymphangiogenesis by salicylates and the other NSAIDs have not been investigated. Although further research validation is needed, this proposed effect of NSAIDs might have therapeutic implications in chemoprevention, adjuvant chemotherapy, and treatment of metastatic disease.

Expressions of COX-2 and VEGF-C in gastric cancer: correlations with lymphangiogenesis and prognostic implications

Background

Cyclooxygenase-2 (COX-2) has recently been considered to promote lymphangiogenesis by up-regulating vascular endothelial growth factor-C (VEGF-C) in breast and lung cancer. However, the impact of COX-2 on lymphangiogenesis of gastric cancer remains unclear. This study aims to test the expression of COX-2 and VEGF-C in human gastric cancer, and to analyze the correlation with lymphatic vessel density (LVD), clinicopathologic features and survival prognosis.

Methods

Using immunohistochemistry, COX-2, VEGF-C and level of LVD were analyzed in 56 R0-resected primary gastric adenocarcinomas, while paracancerous normal mucosal tissues were also collected as control from 25 concurrent patients. The relationships among COX-2 and VEGF-C expression, LVD, and clinicopathologic parameters were analyzed. The correlations of COX-2, VEGF-C and level of LVD with patient prognosis were also evaluated by univariate tests and multivariate Cox regression.

Results

The expression rates of COX-2 and VEGF-C were 69.64% and 55.36%, respectively, in gastric carcinoma. Peritumoral LVD was significantly higher than that in both normal and intratumoral tissue (P < 0.05). It was significantly correlated with lymph node metastasis and invasion depth (P = 0.003, P = 0.05). VEGF-C was significantly associated with peritumoral LVD (r = 0.308, P = 0.021). However, COX-2 was not correlated with VEGF-C (r = 0.110, P = 0.419) or LVD (r = 0.042, P = 0.758). Univariate analysis showed that survival time was impaired by higher COX-2 expression and higher peritumoral LVD. Multivariate survival analysis showed that age, COX-2 expression and peritumoral LVD were independent prognostic factors.

Conclusions

Although COX-2 expression was associated with survival time, it was not correlated with VEGF-C and peritumoral LVD. Our data did not show that overexpression of COX-2 promotes tumor lymphangiogenesis through an up-regulation of VEGF-C expression in gastric carcinoma. Age, COX-2 and peritumoral LVD were independent prognostic factors for human gastric carcinoma.

Tumor lymphangiogenesis and melanoma metastasis

Malignant melanomas of the skin primarily metastasize to lymph nodes, and the detection of sentinel lymph node metastases serves as an important prognostic parameter. There is now compelling evidence that melanomas can induce lymphangiogenesis (growth of lymphatic vessels), mainly at the tumor-stroma interface, and that the level of tumor lymphangiogenesis is correlated with the incidence of sentinel lymph node metastases and with disease-free survival. Thus, tumor lymphangiogenesis can serve as a novel prognostic predictor in melanoma. Vascular endothelial growth factor (VEGF)-C, released by melanoma cells and by tumor-associated macrophages, likely represents the major lymphangiogenic factor in melanoma, although other members of the VEGF family might also be involved. The recent discovery that tumors can induce a premetastatic niche, by inducing lymphatic vessel growth in sentinel lymph nodes even before metastasis, and that lymph node lymphangiogenesis enhances metastatic spread, indicates that activated lymphatic vessels represent novel targets for the detection and/or therapy of melanoma metastases.

Inhibition of cyclooxygenase-2 suppresses lymph node metastasis via reduction of lymphangiogenesis

Cyclooxygenase-2 (COX-2) inhibitor has been reported to suppress tumor progression. However, it is unclear whether this inhibitor can also prevent lymphatic metastasis. To determine the effects of COX-2 inhibitor on lymphatic metastasis, etodolac, a COX-2 inhibitor, was given p.o. to mice bearing orthotopic xenografts or with carcinomatous peritonitis induced with a highly metastatic human diffuse-type gastric carcinoma cell line, OCUM-2MLN. Tumor lymphangiogenesis was significantly decreased in etodolac-treated mice compared with control mice. Consistent with this decrease in lymphangiogenesis, the total weight of metastatic lymph nodes was less in etodolac-treated mice than in control mice. Immunohistochemical analysis revealed that the major source of vascular endothelial growth factor-C (VEGF-C) and VEGF-D was F4/80-positive macrophages in our models. The mRNA levels of VEGF-C in mouse macrophage-like RAW264.7 cells, as well as those in tumor tissues, were suppressed by etodolac. The growth of human dermal lymphatic microvascular endothelial cells was also suppressed by etodolac. Supporting these findings, etodolac also inhibited lymphangiogenesis in a model of chronic aseptic peritonitis, suggesting that COX-2 can enhance lymphangiogenesis in the absence of cancer cells. Our findings suggest that COX-2 inhibitor may be useful for prophylaxis of lymph node metastasis by reducing macrophage-mediated tumor lymphangiogenesis.

Expression of cyclooxygenase-2 and vascular endothelial growth factor-C correlates with lymphangiogenesis and lymphatic invasion in human gastric cancer

BACKGROUND

Recent observations have suggested that overexpression of cyclooxygenase-2 (COX-2) promotes tumor lymphangiogenesis through an upregulation of vascular endothelial growth factor-C (VEGF-C) expression. It is unclear whether this mechanism also acts in gastric cancer. The aim of this study was to determine the relationship between COX-2 and VEGF-C expression in human gastric cancer, as well as to correlate with lymph node involvement, prognosis, and other clinicopathologic parameters.

METHODS

Sixty-eight primary gastric cancers were immunohistochemically examined for COX-2, VEGF-C, vascular endothelial growth factor receptor-3 (VEGFR-3, also known as Flt-4), and CD34 expressions. Assessment of Flt-4-positive vessel density (FVD) and microvessel density (MVD) was performed. Then we analyzed their relationships and correlations with clinicopathologic findings and patients' survival time.

RESULTS

The positivity rate of COX-2 and VEGF-C in the primary tumor was 67.7 and 54.4 percent, respectively. A significant correlation was found between the expression of VEGF-C and COX-2, and both were also correlated to MVD, FVD, lymphatic invasion, and TNM stage (p<0.05). COX-2 immunoreactivity was also associated with lymph node metastasis and serosa invasion. Increased MVD was significantly associated with lymph node metastasis and TNM stage. Both COX-2 and VEGF-C expression significantly correlated with poorer prognosis.

CONCLUSIONS

Our data suggest that the expression of COX-2 correlates with VEGF-C expression and both of them correlate with the presence of lymphatic invasion and prognosis in gastric cancer. COX-2-mediated VEGF-C overexpression might promote lymphatic invasion via lymphangiogenesis pathway in patients with gastric cancer.

Potential therapeutic strategies for lymphatic metastasis

Physiologically, the lymphatic system regulates fluid volume in the interstitium and provides a conduit for immune cells to travel to lymph nodes, but pathologically, the lymphatic system serves as a primary escape route for cancer cells. Lymphatic capillaries have a thin discontinuous basement membrane, lack pericyte coverage and often contain endothelial cell gaps that can be invaded by immune cells (or tumor cells). In addition, tumor cells and stromal cells in the tumor microenvironment secrete factors that stimulate lymphangiogenesis, the growth of lymphatic endothelial cells and the sprouting of lymphatic capillaries. As a result, many tumors are surrounded by large, hyperplastic, peri-tumoral lymphatic vessels and less frequently are invaded by intra-tumoral lymphatic vessels. Carcinoma cells commonly metastasize through these lymphatic vessels to regional lymph nodes. The presence of metastatic cells in the sentinel lymph node is a prognostic indicator for many types of cancer, and the degree of dissemination determines the therapeutic course of action. Lymphangiogenesis is currently at the frontier of metastasis research. Recent strides in this field have uncovered numerous signaling pathways specific for lymphatic endothelial cells and vascular endothelial cells. This review will provide an overview of tumor lymphangiogenesis and current strategies aimed at inhibiting lymphatic metastasis. Novel therapeutic approaches that target the tumor cells as well as the vascular and lymphatic endothelial compartments are discussed.

Effects of prostaglandin E2 on expression of vascular endothelial growth factor in human gastric cancer cell line MKN28

AIM: To investigate the expression of vascular endothelial growth factor (VEGF) in human gastric cell line MKN28 in vitro, and identify whether exogenous prostaglandin E₂ (PGE₂) can increase the expression of VEGF.

METHODS: Human gastric cell line MKN28 was culture in vitro and then treated with 0.1, 1, 5, and 10 μmol/L PGE₂ for 3 h. Real-time polymerase chain reaction (PCR) and Western blot were used to detect the expression of VEGF mRNA and protein, respectively.

RESULTS: The transcription of VEGF mRNA increased in a dose-dependent manner after PGE₂ treatment, and the difference between the groups of 0.1, 1, 5, 10 μmol/L PGE₂ treatment and the control group had statistical significances (0.67 ± 0.093, 0.74 ± 0.13, 0.87 ± 0.07, 1.49 ± 0.15 vs 0.42 ± 0.10, P < 0.05 or P < 0.01). PGE₂ also up-regulated the expression of VEGF protein in a dose-dependent manner, and except 0.1 μmol/L PGE₂ treatment group, the difference between the groups of 1, 5, 10 μmol/L PGE₂ treatment and the control group had statistical significances (51.02 ± 2.16, 66.69 ± 9.85, 136.49 ± 6.89 vs 26.87 ± 3.98, P < 0.05 or P < 0.01).

CONCLUSION: PGE₂ can promote VEGF mRNA transcription and protein expression in human gastric cancer cell line MKN28.

Effect of Ezhu on expression of cyclooxygenase, vascular endothelial growth factor and prostaglandin E2 in human gastric cancer cell line SGC7901

AIM: To investigate the effect of Ezhu on the expression of cyclooxygenase-1 (COX-1), cyclooxygenase-2 (COX-2), vascular endothelial growth factor (VEGF) and prostaglandin E₂ (PGE₂) in human gastric cancer cell line SGC7901.

METHODS: The MTT method was used to observe the suppression of the human gastric cancer (SGC7901) cells treated with Ezhu. By drawing the suppression rate curves, we selected the appropriate Ezhu concentration at the 25% proliferation suppression rate as experimental concentration. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blot were adopted, respectively, to examine the expression of COX gene and protein. Furthermore, ELISA method was used to detect the variation of the VEGF and PEG₂ expression in culture medium.

RESULTS: Ezhu definitely inhibited the proliferation of human gastric cancer cells in a concentration dependent manner. Electrophoresis of the RT-PCR products demonstrated the expression of COX-1 and COX-2 gene in the human gastric cancer cells. Gray scale analysis showed that both Ezhu and celecoxib inhibited the expression of COX-1 and COX-2 gene, and the inhibitory action of Ezhu was greater than celecoxib. However, Western blot clearly showed that a specific protein strip was observed in COX-1 group at the 70 kDa, while in COX-2 group at the 80 kDa. Gray scale analysis confirmed than both Ezhu and celecoxib had apparent suppression on COX-2 protein, but had no effect on COX-1. Moreover, the suppression function of Ezhu surpassed celecoxib. Ezhu and celecoxib obviously degraded the content of VEGF in gastric cancer cells. In comparison with those in the control group, the results are statistically significant (91.0 ± 18.2, 127.8 ± 12.1 ng/L vs 162.0 ± 15.1 ng/L, P < 0.01). The level of PGE₂ in the cells treated with celecoxib was lower than the control group with no statistical significance. Nevertheless, Ezhu decreased the level of PGE₂ significantly (67.5 ± 6.9 ng/L vs 78.7 ± 5.6 ng/L, P < 0.01).

CONCLUSION: Ezhu can inhibit COX-2 and its downstream expression of PGE₂, and down-regulates VEGF expression, so as to suppress the proliferation of gastric cancer cells.