Clinicopathological significance of vascular endothelial growth factor-C and cyclooxygenase-2 in esophageal squamous cell carcinoma

Diagnostic and therapeutic implications of the vascular endothelial growth factor family in cancer

Cancer progression is attained by uncontrolled cell division and metastasis. Increase in tumor size triggers different vascular channel formation to address cell nutritional demands. These channels are responsible for transferring of nutrients and gaseous to the cancer cells. Cancer vascularization is regulated by numerous factors including vascular endothelial growth factors (VEGFs). These factors play an important role during embryonic development. Members included in this group are VEGFA, VEGFB, VEGFC, PIGF and VEGFD which markedly influence cellular growth and apoptosis. Being freely diffusible these proteins act in both autocrine and paracrine fashions. In this review, genetic characterization these molecules and their putative role in cancer staging has been elaborated. Prognostic significance of these molecules along with different stages of cancer has also been summarized. Brief outline of ongoing efforts to target hot spot target sites against these VEGFs and their cognate limitations for therapeutic implications are also highlighted.

Genetic Variations of Kinase Inserts Domain Receptor (KDR) Gene Are Associated with the Risk of Astrocytomas

Astrocytomas is one of the most common central nervous system (CNS) tumors with high mortality rate. Kinase insert domain receptor (KDR) is involved in the regulation of tumor angiogenesis, migration, and vascular permeability. The aim of the study was to explore the relationship between KDR polymorphisms and risk of astrocytomas. Blood samples were collected from 157 astrocytomas patients and 160 healthy controls. Three tag-SNPs (rs2071559C/T, rs2305948T/C, and rs1870377A/T) were identified from the International HapMap Project Databases and genotyped using the method of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). We evaluated the astrocytomas risk caused by individual SNPs and haplotype using odds ratios (ORs) and their 95 % confidence intervals (CIs). In the overall individual SNP analysis, the C allele of rs2071559 was correlated with an increased risk of astrocytomas. However, individuals with mutant allele A and genotype TA + AA of rs1870377 showed a protective effect against astrocytomas. Subgroup analysis based on WHO tumor grade revealed that the C allele of rs2071559 had more influence with the risk of astrocytomas in the grade III-IV (OR = 1.91) subgroup than the grade I-II (OR = 1.47) group. Genotype TT of rs2305948 was found to be significantly associated with susceptibility of astrocytomas only in the grade III-IV subgroup. The protective effect of rs1870377 did not reveal significant difference between the grade III-IV and grade I-II subgroups. Meanwhile, stratified analysis demonstrated that mutation of rs2071559 and rs2305948 could elevate the risk of astrocytomas more significantly in the subgroup of smokers than the nonsmokers. Interestingly, the protective effect of rs1870377 was more obvious in the nonsmokers than the smokers. Additionally, haplotype-specific analysis showed that haplotype CCT and CTT were related with an increased risk of astrocytomas. We found that individual with variants of rs2071559*C and rs2305948*T might significantly elevate the risk of astrocytomas, while mutants of rs1870377*A was associated with the decreased risk of astrocytomas. Further studies about ethnically diverse populations with larger sample size should be performed to confirm the correlation between KDR gene polymorphisms and risk of astrocytomas.

Vascular endothelial growth factor-C expression as a biomarker of poor prognosis in esophageal squamous cell carcinoma: a meta-analysis

BACKGROUND

Vascular endothelial growth factor C (VEGF-C) is involved in the development and progression of tumor angio-/lymphangiogenesis. The purpose of this study is to evaluate whether VEGF-C expression is an indicator of aggressiveness and poor prognosis of esophageal squamous cell carcinoma (ESCC).

METHOD

A meta-analysis was conducted to investigate the association between VEGF-C expression with clinicopathological characteristics and survival of ESCC patients. The dataset was defined by searching PubMed, Embase, Google Scholar, and the Cochrane database for appropriate articles published until April 2014.

RESULT

The final analysis was made from 9 studies, including 656 ESCC patients. Positive VEGF-C expression was defined by immunohistochemistry (IHC) or mRNA expression analysis. The results demonstrated that VEGF-C expression was significantly associated with advanced-stage disease (odds ratio (OR) = 2.29, 95% confidence interval (CI) = 1.37-3.84, P = 0.002), deeper tumor invasion, lymph node metastasis, and lymphatic invasion. The 5-year survival of VEGF-C expression-negative patients was found to be better than that of VEGF-C expression-positive patients (OR = 0.35, 95% CI = 0.21-0.58, P < 0.0001). However, there was no significant association between the VEGF-C expression levels and either poorer tumor differentiation or vascular invasion.

CONCLUSION

The results of the meta-analysis strongly indicate that VEGF-C expression could function as a marker for predicting the aggressiveness and prognosis of ESCC.

Cytokines association with clinical and pathological changes in esophageal squamous cell carcinoma

Carcinogenic transformation of cells in esophageal squamous cell carcinoma (ESCC) is characterized on molecular level by, among other things, changes in protein expression. Among all proteins related to inflammation, cytokines may be implicated as possible biological markers of esophageal cancer. These biomarkers, near imaging techniques, may be helpful in diagnosis and monitoring therapy in ESCC patients. This review demonstrates findings of researches on dysregulation of cytokines in ESCC and their clinical and pathological implications. Articles on cytokines were selected according to the following criteria: (i) the study was performed at protein level, (ii) the differences in cytokines expression or concentration were detected in tissues or serum from ESCC patients, (iii) the alterations of cytokines levels were detected by: immunohistochemistry (IHC), western blot (WB) and enzyme-linked immunosorbent assay (ELISA). Members of VEGF family seem to play an essential role as potential markers in ESCC. The results of all cytokines researches are promising but further studies are necessary to establish the biological significance of these peptydes in ESCC, their potential usefulness for early diagnosis, pre- and postoperative prognosis and monitoring of the respond to chemo- and radiotherapy of cancer patients.

Double-positive expression of high-mobility group box 1 and vascular endothelial growth factor C indicates a poorer prognosis in gastric cancer patients

Background

Although many studies have indicated that high-mobility group box 1 protein (HMGB1) is associated with oncogenesis and a worse prognosis, the prognostic value of HMGB1 in gastric cancer (GC) remains unclear. In the present work, we aimed to evaluate the role of HMGB1 in GC and examined whether aberrant expression of both HMGB1 and vascular endothelial growth factor C (VEGF-C) increased the malignant potential of GC.

Methods

A total of 166 GC patients and 32 normal subjects were enrolled. HMGB1 and VEGF-C expression was detected by tissue microarrays (TMAs) and immunohistochemical staining. The correlation between HMGB1 and VEGF-C expression and their relationships with clinicopathological GC variables were examined. Univariate and multivariate analyses were performed using the Cox proportional hazard model to predict the factors related to the patients‘ overall survival rates.

Results

HMGB1 and VEGF-C expression were observed in 81 (48.80%) and 88 (53.01%) tumors, respectively, significantly higher than the rates among the corresponding controls. In addition, HMGB1 and VEGF-C expression were positively correlated (R² = 0.972). HMGB1 expression was also closely associated with tumor size, pT stage, nodal status, metastasis status, TNM stage, and poor prognosis. Multivariate survival analysis indicated that patients with HMGB1 and VEGF-C coexpression had the worst prognoses and survival rates (hazard ratio, 2.78; log rank P<0.001).

Conclusions

HMGB1 is commonly expressed in GC. Combined evaluation of HMGB1 and VEGF-C may serve as a valuable independent prognostic factor for GC patients.

Expression and significance of vascular endothelial growth factor C from multiple specimen sources in esophageal squamous cell carcinoma

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is a common malignancy with a very poor prognosis. Vascular endothelial growth factor C (VEGF-C) plays an important role in angiogenesis and lymphangiogenesis. This study was designed to analyze the correlation of VEGF-C expression with clinicopathological features and survival in multiple specimen sources from patients with ESCC.

MATERIAL AND METHODS

The expression of VEGF-C in tissues (tVEGF-C), serum (sVEGF-C), and lymph fluid (lVEGF-C) from 48 patients with ESCC was detected by different methods.

RESULTS

There were significant correlations between a high level of tVEGF-C expression and tumor differentiation, tumor depth, lymph node metastasis, TNM stage and metastasis. sVEGF-C was only significantly related to lymph node metastasis, TNM stage and metastasis. The results of lVEGF-C expression were similar to those of tVEGG-C expression, but no relationship to tumor depth was found. High expression levels of tVEGF-C, sVEGF-C and lVEGF-C were significantly associated with shorter overall survival times in univariate analysis (log-rank test).

CONCLUSIONS

The expression of VEGF-C in multiple specimen sources from patients with ESCC was associated with certain clinicopathological parameters. High expression of VEGF-C may be an important factor related to a poor prognosis of ESCC.

The relationship between GLUT-1 and vascular endothelial growth factor expression and 18F-FDG uptake in esophageal squamous cell cancer patients

PURPOSE

To examine the relationship between glucose transporter-1 (GLUT-1) and vascular endothelial growth factor (VEGF) expression and (18)F-FDG uptake in esophageal squamous cell cancer patients.

MATERIALS AND METHODS

Fifty-seven patients (52 male and 5 female) were included in this study. (18)F-FDG PET/CT was performed prior to the surgery. Immunohistochemistry was performed using postoperative histopathological specimens. The estimation of immunohistochemistry was conducted using scoring analysis. We investigated the correlations between maximum standardized uptake value (SUV(max)) and GLUT-1/VEGF expressions/pathologic tumor length (p-tumor length), and the relationships between pathologic T (p-T) stage and GLUT-1/VEGF expressions/SUV(max) and between lymph node metastasis (p-N) stage and GLUT-1/VEGF expressions/SUV(max).

RESULTS

SUV(max) significantly correlated with GLUT-1 expressions and p-tumor length (GLUT-1: r = 0.475, P < 0.001; p-tumor length: r = 0.475, P < 0.001). SUV(max) of the primary tumor had a significant relationship with p-T stage, p-N stage, and VEGF expression (p-T stage: P < 0.001; p-N stage: P = 0.037; VEGF expression: P = 0.009). There was a statistically significant difference between GLUT-1 expression and p-T stage/VEGF expression, but not p-N stage (p-T stage: P = 0.012; VEGF expression: P = 0.01; p-N stage: P = 0.572). VEGF expression had a significant relationship with p-T stage, but not with p-N stage (p-T stage: P = 0.032; p-N stage: P = 0.763).

CONCLUSION

(18)F-FDG uptake can be determined by GLUT-1 and VEGF. SUV(max) would have a connection with the tumor progression and lymph node metastasis.

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.

Vascular endothelial growth factor receptor 2 (VEGFR-2) signalling activity in paediatric pilocytic astrocytoma is restricted to tumour endothelial cells

AIMS

Tumours depend on angiogenesis for enhanced tumour cell survival and progression. Vascular endothelial growth factor receptor (VEGFR) signalling plays a major part in this process. Previously, we evaluated tyrosine kinase activity in paediatric brain tumour tissue lysates using a peptide microarray containing 144 different tyrosine kinase peptide substrates. When applied to paediatric pilocytic astrocytoma tissue, this analysis revealed extensive phosphorylation of VEGFR-derived peptides. The aim of the current study was to validate this result and determine the presence of VEGFR-2 activity in paediatric pilocytic astrocytoma as the main VEGFR in terms of mitogenic signalling. In addition, the localization of VEGFR1-3 mRNA expression was assessed.

METHODS

VEGFR-2 phosphorylation was determined by adopting a proximity ligation assay approach. Enrichment of endothelial markers and VEGFRs in tumour endothelium was determined by quantitative polymerase chain reaction (qPCR) analysis of laser-microdissected blood vessels.

RESULTS

Proximity ligation assays on tumour cryosections showed the presence of phosphorylation of VEGFR-2, which primarily localized to vascular endothelium. qPCR analysis of endothelial markers and VEGFRs showed a 13.6-fold average enrichment of VEGFR-2 expression in the laser-microdissected endothelium compared to whole tumour. Also the expression of VEGFR-1 and -3 was highly enriched in the endothelium fraction with an average fold-enrichment of 16.5 and 50.8 respectively.

CONCLUSIONS

Phosphorylated VEGFR-2 is detected on endothelial cells in paediatric pilocytic astrocytoma. Furthermore, endothelial cells are the main source of VEGFR1-3 mRNA expression. This suggests a crucial role for VEGF/VEGFR-induced angiogenesis in the progression and maintenance of these tumours.

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.

Coexpression of VEGF-C and COX-2 and its association with lymphangiogenesis in human breast cancer

Background

Lymphangiogenesis has become a new research frontier in tumor metastasis since the discovery of reliable lymphatic markers that have allowed observation and isolation of lymphatic endothelium. Cyclooxygenase-2 (COX-2) has been reported to be involved in the critical steps in carcinogenesis. However, possible role of COX-2 in lymphangiogenesis and lymphatic metastasis is still poorly understood. In present study, we aimed to investigate the relationship between vascular endothelial growth factor-C (VEGF-C) and COX-2 in human breast cancer, and correlations with lymphangiogenesis and prognosis.

Methods

Tissue samples of primary tumors from 70 patients undergoing intentionally curative surgical resections for breast cancer were immunohistochemically examined for VEGF-C, COX-2, and D2-40 expressions. The association between COX-2 and VEGF-C expressions and clinicopathological parameters as well as prognosis were analysised. To demonstrate the presence of proliferating lymphatic endothelial cells, 10 random cases with high LVD counts were selected for D2-40/Ki-67 double immunostaining.

Results

A significant correlation was found between the expression of VEGF-C and COX-2 (r = 0.529, P < 0.001), and both elevated VEGF-C expression and elevated COX-2 expression were associated with higher lymph vessel density (LVD), lymph node metastasis and D2-40 positive lymphatic invasion (LVI) as well as worse disease free survival (DFS) and overall survival (OS) in a univariate analysis. In the double immunostain for the lymph vessel marker D2-40 and the proliferation marker Ki-67, the results confirmed Ki-67-positive nuclei in a proportion of lymph vessel endothelial cells.

Conclusion

There is indeed lymphangiogenesis in breast cancer, the most compelling evidence being the presence of proliferating lymphatic endothelial cells. VEGF-C and COX-2 are coexpressed and significantly associated with lymphangiogenesis and prognosis in invasive breast cancer. Suggesting COX-2 may up-regulate VEGF-C expression and thus promote lymph node metastasis via lymphangiogenesis pathway in human breast cancer.

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.

Expressions of p53, VEGF C, p21: could they be used in preoperative evaluation of lymph node metastasis of esophageal squamous cell carcinoma?

The prognosis of esophageal squamous cell carcinoma is primarily determined by staging. Although radiological methods have revealed lymph node metastasis preoperatively, these radiological findings cannot be correlated with pathological staging. The aim of this study was to compare the expressions of p53, vascular endothelial growth factor C (VEGF C) and p21 with lymph node metastasis in preoperative endoscopic biopsy and postoperative resection material. Tissue samples were taken from 40 patients who had undergone endoscopic biopsies and radical esophagectomies. The expressions of p53, VEGF C and p21 proteins in these sections were immunohistochemically examined. The expression of each antibody was characterized as a negative or positive reaction according to the pattern and intensity of semiquantitative immunostaining. The staining pattern of antibodies was divided into three groups: < 10% cancer cells were accepted to be (-), 10-50% were (+), heterogenous and > 50% were (+ +), homogenous. For each antibody, statistical correlation with conventional prognostic parameters such as localization, microscopic grade, stage, pathological lymph node metastasis and survival, were investigated. p53 expression was observed in 65.5% (19/29) of lymph node positive cases, whereas p53 was in 50% (20/40) of cases. VEGF C was in 65% (26/40) and p21 was in 15% (6/40) of cases. p53 has the specificity of 90.9% and sensitivity rate of 65.5% in detecting lymph node metastasis and positive predictive value was 95%. Expression of p53 was significantly correlated with stage and lymph node metastasis (P = 0.02 and P = 0.03, respectively). Prediction of lymph node metastasis by p53 was correlated independently and in coexpression with VEGF C (P < 0.01). There was no relation detected between p21 and other parameters. In esophageal squamous cell carcinoma (SCC), p53 and VEGF C expressions were correlated with pathologically positive lymph nodes. When preoperative staging has been insufficient in esophageal carcinoma cases, immunohistochemical analysis of p53 and VEGF C staining in tissues could be an aid to clinicians regarding lymph node metastasis.

Clinical significance of cyclooxygenase-2 expression in extranodal natural killer (NK)/T-cell lymphoma, nasal type

PURPOSE

To determine whether there are any differences in therapeutic response, patterns of systemic recurrence, and prognosis of patients with extranodal natural killer (NK)/T-cell lymphoma, nasal type, by the cyclooxygenase-2 (COX-2) expression.

PATIENTS AND METHODS

Thirty-four patients with Ann Arbor Stage I and II extranodal NK/T-cell lymphoma who underwent chemotherapy or radiotherapy, or both, were retrospectively reviewed. These patients were divided into two groups according to their immunohistochemical staining for COX-2 expressions: a COX-2-negative group (n = 10 patients) and a COX-2-positive group (n = 24 patients). The treatment response, patterns of treatment failure, and survival data for the patients were compared between the COX-2-positive and negative groups.

RESULTS

There was no significant difference in the clinical profiles between the COX-2-negative and COX-2-positive groups. All patients (100%) in the COX-2-negative group achieved complete response after initial treatment, whereas only 14 patients (58%) in the COX-2-positive group achieved complete response (p = 0.03). Compared with the patients in the COX-2-negative group, those in the COX-2-positive group had a significantly lower 2-year systemic recurrence-free survival rate (100% for the COX-2-negative group vs. 54% for the COX-2-positive group) (p = 0.02) and a decreased 5-year overall survival rate (70% for the COX-2-negative group vs. 32% for the COX-2-positive group) (p = 0.06).

CONCLUSION

Cyclooxygenase-2 expression can serve as a predictive factor for poor treatment response, higher systemic recurrence, and unfavorable prognosis in patients with extranodal NK/T-cell lymphoma, nasal type.

Expression of VEGFR3 in glioma endothelium correlates with tumor grade

Angiogenic processes are regulated by vascular endothelial growth factors (VEGFs) and their receptors VEGFR1 (Flt-1), 2 (Flk-1) and 3 (Flt-4). While VEGFR2 is thought to play a central role in tumor angiogenesis, anti-angiogenic therapies targeting VEGFR2 in glioma models can show escape phenomena with secondary onset of angiogenesis. The purpose of this study was to find explanations for these processes by searching for alternative pathways regulating glioma angiogenesis and reveal a correlation with tumor grade. Thus, VEGFR3, which is not expressed in normal brain, and its ligands VEGF-C and -D, were assessed in high grade (WHO degrees IV, glioblastomas, GBM) and low grade gliomas [WHO degrees II astrocytomas (AII)]. In all GBM, a strong protein expression of VEGFR3 was found on tumor endothelium, VEGF-C and -D expression was found on numerous cells in areas of high vascularization. On RNA level, a significant up-regulation of VEGFR3 was detected in GBM compared to AII and non-neoplastic brain. In AII, only very moderate VEGFR3, VEGF-C and -D expression was found on protein and RNA level indicating a correlation of VEGFR3 expression with tumor grade. VEGFR3 signal in both grades was found predominantly on endothelial cells, confirmed by VEGFR3 expression on isolated CD31 positive cells and the expression of various endothelial markers on VEGFR3-positive cells isolated from GBM. The demonstration of a complete angiogenic signaling system that is dependent on tumor grade may influence the traditional paradigm of glioma angiogenesis and may provide a basis for more effective anti-angiogenic treatment strategies.

Up-regulation of VEGF-C secreted by cancer cells and not VEGF-A correlates with clinical evaluation of lymph node metastasis in esophageal squamous cell carcinoma (ESCC)

Tissue expression of VEGF-C correlates with lymph node involvement (LNI) in ESCC and serum VEGF-C (sVEGF-C) in a non-small cell lung cancer has been more accurate marker of LNI than chest CT. Despite LNI importance in ESCC, the usefulness of serum VEGF-C (sVEGF-C) as a disease and LNI marker in ESCC has not been investigated yet. We found elevated sVEGF-C in ESCC (17.40 vs. 10.57 ng/ml in controls, p<0.001). It proved to be a better ESCC marker than described elsewhere: CEA, CA19-9 and SCC-Ag, with: sensitivity--70%, specificity--81%, accuracy--83.7%. Analysis of sVEGF-C correlation with clinico-pathological cancer features revealed relation to LNI (N0: 15.77 vs. N1: 21.78 ng/ml, p=0.02), especially in advanced cancers. Serum VEGF-C as a marker of LNI was characterized by: sensitivity--76%, specificity--58%, accuracy--64.4%. No relation was observed between LNI and sVEGF-A or sVEGF-A/platelets (PLT). Because sVEGF-C was higher in N0 cancers (p<0.01), the tumor presence also up-regulates sVEGF-C. We found sVEGF-C correlation with PLT and WBC: R=0.36 and R=0.32 (p<0.01). Nevertheless, analysis of PLT and WBC dependence on cancer features implies that elevation of sVEGF-C in N1 cancers is not related to them.

COX-2-mediated stimulation of the lymphangiogenic factor VEGF-C in human breast cancer

Increased expression of COX-2 or VEGF-C has been correlated with progressive disease in certain cancers. Present study utilized several human breast cancer cell lines (MCF-7, T-47D, Hs578T and MDA-MB-231, varying in COX-2 expression) as well as 10 human breast cancer specimens to examine the roles of COX-2 and prostaglandin E (EP) receptors in VEGF-C expression or secretion, and the relationship of COX-2 or VEGF-C expression to lymphangiogenesis. We found a strong correlation between COX-2 mRNA expression and VEGF-C expression or secretion levels in breast cancer cell lines and VEGF-C expression in breast cancer tissues. Expression of LYVE-1, a selective marker for lymphatic endothelium, was also positively correlated with COX-2 or VEGF-C expression in breast cancer tissues. Inhibition of VEGF-C expression and secretion in the presence of COX-1/2 or COX-2 inhibitors or following downregulation of COX-2 with COX-2 siRNA established a stimulatory role COX-2 in VEGF-C synthesis by breast cancer cells. EP1 as well as EP4 receptor antagonists inhibited VEGF-C production indicating the roles of EP1 and EP4 in VEGF-C upregulation by endogenous PGE₂. Finally, VEGF-C secretion by MDA-MB-231 cells was inhibited in the presence of kinase inhibitors for Her-2/neu, Src and p38 MAPK, indicating a requirement of these kinases for VEGF-C synthesis. These results, for the first time, demonstrate a regulatory role of COX-2 in VEGF-C synthesis (and thereby lymphangiogenesis) in human breast cancer, which is mediated at least in part by EP1/EP4 receptors.

Alvocidib (Flavopiridol) suppresses tumor growth in SCID mice with human esophageal cancer xenografts without inducing apoptosis

Alvocidib (Flavopiridol, HMR1275) is a potent inhibitor of multiple cyclin-dependent kinases and has been identified recently as an antitumor agent in several cancers. Previous studies have shown that alvocidib could potentially treat esophageal cancer in vitro. This study evaluates alvocidib for its ability to suppress tumor growth in severe combined immunodeficiency (SCID) mice bearing TE8 human esophageal squamous cell carcinoma (SCC) xenografts. Alvocidib treatment of 10mg/kg body weight reduced tumor volume significantly. Immunohistochemistry analysis of alvocidib-treated tumor sections showed significant reductions in cyclin D1, VEGF, and Rb levels. Alvocidib treatment did not cause a marked increase in apoptotic tumor cells by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) analysis, yet hematoxylin and eosin staining revealed tumor necrosis. In vivo investigation of alvocidib treatment confirmed antitumor activity in TE8 esophageal xenografts. These findings suggest that alvocidib could be a useful anti-cancer agent for esophageal cancer.

Coexpression of VEGF-C and Cox-2 in human colorectal cancer and its association with lymph node metastasis

PURPOSE

Several lines of experimental evidence indicated that over-expression of vascular endothelial growth factor-C and cyclooxygenase-2 genes promotes angiogenesis and lymphangiogenesis, both of which are essential for the growth and spreading of tumor cells. This study was designed to evaluate the coexpression of vascular endothelial growth factor-C and cyclooxygenase-2 in human colorectal carcinoma to determine their relationships and correlations with lymph node metastasis and prognosis.

METHODS

Tissue samples of primary tumors and metastatic lymph nodes from 150 patients undergoing intentionally curative surgical resections for colorectal adenocarcinoma were immunohistochemically examined for vascular endothelial growth factor-C, cyclooxygenase-2, and CD34 expressions. Then, we analyzed their relationships and correlations with clinicopathologic findings and patients' survival time.

RESULTS

The positivity rate of vascular endothelial growth factor-C and cyclooxygenase-2 in the primary tumor was 68 and 72.7 percent, respectively, and in the metastatic lymph nodes was 93.3 and 80 percent, respectively. A significant correlation was found between the expression scores of vascular endothelial growth factor-C and cyclooxygenase-2 (P < 0.0001), and both also were correlated to microvessels density and several clinicopathologic parameters, including primary tumor size, lymph node metastasis, lymphatic invasion, and TNM stage. Patients with vascular endothelial growth factor-C-positive and/or cyclooxygenase-2-positive tumors had a significant shorter survival time than those with negative tumors did. However, in a multivariate analysis, only cyclooxygenase-2 expression was recognized as an independent prognostic factor (P = 0.0412; relative risk ratio, 3.067; 95 percent confidence interval, 1.046-8.994).

CONCLUSIONS

These data show that in human colorectal carcinoma, vascular endothelial growth factor-C and cyclooxygenase-2 are coexpressed and significantly associated with lymph node metastasis and prognosis.

Tumor-induced lymphangiogenesis: a target for cancer therapy?

Recent advances in understanding the biology of lymphangiogenesis, the new growth of lymphatic vessels, have cast new light on the molecular basis of metastasis to regional lymph nodes. The receptor tyrosine kinase VEGFR-3 is virtually exclusively expressed on lymphatic but not blood endothelium in the adult, and activation of VEGFR-3 by its ligands VEGF-C and VEGF-D is sufficient to induce lymphangiogenesis. Correlative studies with human tumors and functional studies using animal tumor models show that increased levels of VEGF-C or VEGF-D in tumors lead to enhanced numbers of lymphatic vessels in the vicinity of tumors, which in turn promotes metastasis to regional lymph nodes by providing a greater number of entry sites into the lymphatic system for invading tumor cells. These findings have prompted studies to investigate whether inhibitors of VEGFR-3 activation might represent novel therapeutic agents for the suppression of metastasis. However, a number of points regarding the therapeutic potential of anti-lymphangiogenic treatments in the context of cancer remain to be addressed. The spectrum and relative importance of molecules that induce lymphangiogenesis and the regulation of their expression during tumor progression, the reversibility of tumor-induced lymphangiogenesis, and possible side-effects of anti-lymphangiogenesis-based therapies all need to be investigated. Most importantly, the extent to which lymph node metastases contribute to the formation of metastases in other organs remains to be elucidated. These aspects are the focus of this review, and their investigation should serve as a roadmap to possible translational application.