Vascular endothelial growth factor-C expression correlates with lymph node localization of human melanoma metastases

Antiangiogenic activity of Andrographis paniculata extract and andrographolide

Inhibition of angiogenesis is currently perceived as one of the promising strategies in the treatment of cancer. In this study we analyzed the antiangiogenic activity of Andrographis paniculata extract (APE) and its major component andrographolide (ANDLE) using both in vitro and in vivo models. Intraperitoneal administration of APE and ANDLE significantly inhibited the B16F-10 melanoma cell line induced capillary formation in C57BL/6 mice. Analysis of serum cytokine profile showed a drastic elevation in the proinflammatory cytokines such as IL-1beta, IL-6, TNF-alpha and GM-CSF and the most potent angiogenic factor VEGF in angiogenesis induced animals. Treatment of APE and ANDLE significantly reduced this elevated levels. Moreover, VEGF mRNA level in B16F-10 cell line showed a reduced level of expression in the presence of APE and ANDLE. Serum NO level which was increased in B16F-10 melanoma injected control animals was also found to be significantly lowered by the administration of APE and ANDLE. Antiangiogenic factors such as TIMP-1 and IL-2 level was elevated in APE and ANDLE treated angiogenesis induced animals. In the rat aortic ring assay APE and ANDLE inhibited the microvessel outgrowth at non toxic concentrations. Taken together our results demonstrate that APE and ANDLE inhibit the tumor specific angiogenesis by regulating the production of various pro and antiangiogenic factors such as proinflammatory cytokine, nitric oxide, VEGF, IL-2 and TIMP-1.

Tumor lymphangiogenesis and metastatic spread-new players begin to emerge

The metastatic spread of tumor cells is the most lethal aspect of cancer and can occur via various routes, including the lymphatic vasculature. Studies of tumor models in animals and clinicopathological data have indicated that growth of lymphatic vessels (lymphangiogenesis) in the vicinity of solid tumors may contribute to lymphatic metastasis. Research over the past 5 years has identified a range of lymphangiogenic growth factors that could conceivably play a role in promoting tumor lymphangiogenesis and lymphatic metastasis. The most extensively studied signaling system that promotes lymphangiogenesis in tumors involves the secreted lymphangiogenic proteins vascular endothelial growth factor-C (VEGF-C) and VEGF-D, and their cognate receptor on lymphatic endothelium VEGF receptor-3 (VEGFR-3). More recent studies have identified other signaling molecules that can also promote lymphangiogenesis in vivo, including hepatocyte growth factor and members of the fibroblast growth factor, angiopoietin, platelet-derived growth factor and insulin-like growth factor families of secreted proteins. This article provides an overview of the molecular mechanisms that control lymphangiogenic signaling, emphasizing the more recently identified lymphangiogenic growth factors and the roles they may play in cancer biology. Molecular approaches for inhibiting lymphangiogenic signaling in cancer, designed to restrict tumor metastasis, are also examined.

The clinicopathologic significance of the expression of vascular endothelial growth factor-C in intrahepatic cholangiocarcinoma

OBJECTIVES

Vascular endothelial growth factor-C (VEGF-C) is known to be an important lymphangiogenetic factor. Lymphatic spread is a key prognostic factor in intrahepatic cholangiocarcinoma (ICC). We studied the expression of VEGF-C in ICC tissues to clarify its clinicopathologic significance.

METHODS

The expression of VEGF-C in surgical specimens obtained from 36 patients with ICC who underwent hepatic resection was examined by immunohistochemistry and Western blotting. Strong staining was defined as the presence of VEGF-C immunoreactivity in at least 50% of the tumor cells. Immunoreactivity in approximately 10% to approximately 50% of the tumor cells was considered as weak staining, and less than 10% as no staining.

RESULTS

Of the 36 patients with ICC, 15 patients (41.7%) showed a strong positive result for VEGF-C. Eleven cases (30.6%) were negative and 10 cases (27.8%) showed weak immunoreactivity. VEGF-C expression was significantly correlated with lymph node metastasis (P = 0.032) and positive surgical margin (P = 0.03). Patients who had strong positive staining for VEGF-C showed significantly less favorable survival rates compared with patients who had negative or weak staining (P < 0.01). Other significant prognostic factors by univariate analysis were vascular invasion, lymph node involvement, and positive surgical margin. Multivariate analysis demonstrated that strong VEGF-C expression (P = 0.028) and vascular invasion (P = 0.021) were independent factors indicating poor prognosis.

CONCLUSIONS

Our data suggest that VEGF-C expression serves as an independent and important prognostic factor in ICC patients, and it may play an important role in the lymph node metastasis of ICC.

Histopathologic Characteristics, Recurrence Patterns, and Survival of 129 Patients With Desmoplastic Melanoma

BACKGROUND

Desmoplastic melanoma (DM) has been associated with higher local recurrence rates than other types of cutaneous melanoma. Current controversies regarding locoregional treatment strategies warrant further investigation.

METHODS

Retrospective review of a prospectively maintained melanoma database identified 129 patients with DM out of >12,500 melanoma patients referred for treatment from 1980 to 2003. Clinical and histopathologic characteristics, recurrence, and survival were analyzed.

RESULTS

The median follow-up was 4.0 years. Of the 129 patients identified, 82 (63.6%) were male, and the median age was 55.2 years. American Joint Committee on Cancer staging was I, II, and III in 25.6%, 68.0%, and 6.4% of patients, respectively, and the mean tumor thickness was 4.42 mm. Overall survival was 76% at 5 years and 64% at 10 years; median survival was 13.0 years. A total of 51 patients (39.5%) experienced disease recurrence, with a median time to recurrence of 1.3 years. The first recurrence was local in 18 patients (14.0%), nodal in 18 patients (14.0%), and distant in 15 patients (11.6%), with median survivals of 6.7, 7.8, and 1.8 years, respectively. Statistically significant predictors of recurrence were a final positive margin status and stage, and predictors of overall survival were patient age and stage.

CONCLUSIONS

Compared with other types of melanoma, DMs do demonstrate a tendency toward local recurrence, thus suggesting that narrower excision margins may not be appropriate in this population. Scrutiny of final surgical margins is critical to the local management of DM. In addition, the potential for regional nodal involvement must be considered at the time of diagnosis and during surveillance for disease recurrence.

Tumour lymphangiogenesis is a possible predictor of sentinel lymph node status in cutaneous melanoma: a case-control study

BACKGROUND

Cutaneous melanoma spreads preferentially through the lymphatic route and sentinel lymph node (SLN) status is regarded as the most important predictor of survival.

AIMS

To evaluate whether tumour lymphangiogenesis and the expression of vascular endothelial growth factor C (VEGF-C) is related to the risk of SLN metastasis and to clinical outcome in a case-control series of patients with melanoma.

METHODS

Forty five invasive melanoma specimens (15 cases and 30 matched controls) were investigated by immunostaining for the lymphatic endothelial marker D2-40 and for VEGF-C. Lymphangiogenesis was measured using computer assisted morphometric analysis.

RESULTS

Peritumorous lymphatic vessels were more numerous, had larger average size, and greater relative area than intratumorous lymphatics. The number and area of peritumorous and intratumorous lymphatics was significantly higher in melanomas associated with SLN metastasis than in non-metastatic melanomas. No significant difference in VEGF-C expression by neoplastic cells was shown between metastatic and non-metastatic melanomas. Using logistic regression analysis, intratumorous lymphatic vessel (LV) area was the most significant predictor of SLN metastasis (p = 0.04). Using multivariate analysis, peritumorous LV density was an independent variable affecting overall survival, whereas the intratumorous LV area approached significance (p = 0.07).

CONCLUSIONS

This study provides evidence that the presence of high peritumorous and intratumorous lymphatic microvessel density is associated with SLN metastasis and shorter survival. The intratumorous lymphatic vessel area is the most significant factor predicting SLN metastasis. The tumour associated lymphatic network constitutes a potential criterion in the selection of high risk patients for complementary treatment and a new target for antimelanoma therapeutic strategies.

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.

Lymphangiogenesis correlates with lymph node metastasis, prognosis, and angiogenic phenotype in human non-small cell lung cancer

PURPOSE

Recent experimental studies have revealed that lymphangiogenesis plays an important role in cancer progression, but its clinical significance in the case of non-small cell lung cancer (NSCLC) remains unclear. Our aim was to assess the lymphangiogenesis of human NSCLC, and to correlate this with angiogenic phenotype (angiogenic versus nonangiogenic growth pattern) and clinical behavior.

EXPERIMENTAL DESIGN

One hundred and three patients with NSCLC and complete follow-up information were included. Tumor samples were immunostained for vascular endothelial growth factor-C (VEGF-C), the lymphatic endothelial markers, LYVE-1 and D2-40/Podoplanin, and the panvascular marker, CD31. Lymphatic vessel density (LVD) and perimeters were evaluated within the tumor and peritumorally.

RESULTS

LVDs at the tumor periphery were significantly higher in lymph node metastatic tumors (P < 0.005) and high LVDs correlated with poor overall survival (P < 0.001). However, this tendency proved to be significant only in the angiogenic tumor group (P < 0.001). Although 68% of the patients with nonangiogenic tumors had lymph node metastasis (P = 0.0048 versus angiogenic tumors), in the patient group with nonangiogenic NSCLCs, there was no information from the LVDs in any investigated tumor area (P > 0.05). In contrast to angiogenic tumors, which had actively sprouting lymphatics in all of the investigated tumor areas, nonangiogenic tumors showed no Ki67 staining intratumorally.

CONCLUSIONS

Our results reveal tumor lymphangiogenesis as a novel prognostic indicator for the risk of lymph node metastasis in NSCLC. Moreover, it also provides the first evidence that nonangiogenic NSCLCs mainly co-opt host tissue lymphatics during their growth, in contrast to most of the angiogenic tumors, which expand with concomitant lymphangiogenesis.

Inhibition of lymphogenous metastasis using adeno-associated virus-mediated gene transfer of a soluble VEGFR-3 decoy receptor

The presence of metastases in regional lymph nodes is a strong indicator of poor patient survival in many types of cancer. It has recently been shown that the lymphangiogenic growth factor, vascular endothelial growth factor-C (VEGF-C), and its receptor, VEGF receptor-3 (VEGFR3), may play a pivotal role in the promotion of metastasis to regional lymph nodes. In this study, human prostate and melanoma tumor models that preferentially metastasize to the lymph nodes following s.c. tumor cell implantation were established from lymph node metastases via in vivo selection. Melanoma tumor cell sublines established from lymph node metastasis express higher amounts of VEGF-C than the parental tumor cells. The inhibition of tumor-derived VEGF-C with a soluble VEGFR3 decoy receptor, sVEGFR3-Fc, expressed via a recombinant adeno-associated viral vector, potently blocks tumor-associated lymphangiogenesis and tumor metastasis to the lymph nodes, when the treatment was initiated before the tumor implantation. In addition, sVEGFR3-Fc serum levels required for efficient blockade of lymph node metastases are strictly dependent on the VEGF-C levels generated by the primary tumor. Recombinant adeno-associated virus-mediated gene transfer of sVEGFR3-Fc may represent a feasible therapeutic strategy for blockade of lymphogenous metastasis.

Impact of vascular endothelial growth factor-C and -D expression in human pancreatic cancer: its relationship to lymph node metastasis

PURPOSE

The aim of this study was to evaluate the expression of vascular endothelial growth factor (VEGF)-C and -D in pancreatic cancer and to reveal its relation to lymph node metastasis.

EXPERIMENTAL DESIGN

Formalin-fixed, paraffin-embedded blocks were obtained from 58 patients with pancreatic head cancer. All of the patients underwent a curative resection. The total number of resected lymph nodes was 1,058. The expressions of VEGF-C and -D were evaluated by immunohistochemical staining. To evaluate the relation to lymph node metastasis, the expressions of VEGF-C and -D between the marginal and central portions in the tumor were compared. When >25% of the tumor cells showed distinct staining, the portion was judged as high expression.

RESULTS

The two groups with high expression of VEGF-C (P = 0.015) and VEGF-D (P = 0.020) in the marginal portion had a significantly higher incidence of lymph node metastasis compared with the groups with low expression, respectively. Furthermore, the group with high expression of both VEGF-C and -D in the marginal portion had a higher incidence of lymph node metastasis compared with the group with low expression (P = 0.007). The 5-year survival rate of patients with high expression of both VEGF-C and -D in the marginal portion was significantly lower than that of patients with low expression of both VEGF-C and -D (P = 0.017).

CONCLUSIONS

VEGF-C and -D expression in tumor cells in the marginal portion of the tumor significantly associated with lymphatic metastasis and prognosis in patients with pancreatic head cancer.

Tumor lymphangiogenesis predicts melanoma metastasis to sentinel lymph nodes

Cutaneous melanoma is a common melanocytic neoplasm that can quickly metastasize to regional lymph nodes. Currently, prognosis is determined by measuring tumor thickness but more reliable markers for metastatic spread are urgently needed. We investigated whether the extent of tumor lymphangiogenesis can predict melanoma metastasis to sentinel lymph nodes. We quantified the extent of tumor lymphangiogenesis, as well as other factors, in excised primary tumors and in sentinel lymph node biopsy samples from 45 patients with primary cutaneous melanoma. The results were correlated with histological and clinical outcome. Primary melanomas from patients whose tumors had metastasized to the sentinel lymph nodes contained prominent 'hot spots' of increased lymphatic vessel density, compared to nonmetastatic tumors. Multivariate risk analysis revealed that the lymphatic vascular area of primary melanomas, an index of tumor lymphangiogenesis, was the most sensitive prognostic marker for sentinel lymph node metastasis, and was even able to more accurately predict which tumors were metastatic to sentinel lymph nodes than the currently used method of measuring tumor thickness. Highly lymphangiogenic melanomas maintained their lymphangiogenic activity after metastasis to the sentinel lymph node. The extent of tumor lymphangiogenesis is a highly sensitive (83%) and specific (89%) prognostic marker of lymph node metastasis. Assessment of lymphangiogenesis in primary melanomas may be a more effective approach than the currently used technique of measuring tumor thickness in selecting patients with early metastatic disease for aggressive therapy.

ZD6474--a novel inhibitor of VEGFR and EGFR tyrosine kinase activity

Angiogenesis is crucial for maintaining the supply of oxygen and nutrients required to support solid tumour growth. Inhibitors of tumour blood vessel formation are therefore being sought, in particular, inhibitors of vascular endothelial growth factor-A (VEGF)-signalling, which has a pivotal role in stimulating neovascular growth and survival. ZD6474 is an orally bioavailable inhibitor of VEGF receptor-2 tyrosine kinase activity that in preclinical studies has been shown to inhibit both VEGF-induced signalling in endothelial cells and tumour-induced angiogenesis. Consistent with inhibition of angiogenesis, once-daily oral dosing of ZD6474 produced significant broad-spectrum antitumour activity in a panel of histologically diverse human tumour xenografts. In addition to its antiangiogenic properties, ZD6474 also has activity against the epidermal growth factor receptor (EGFR) tyrosine kinase, which could impart a direct inhibitory effect on tumour cell growth and survival. This may be particularly relevant in tumours with a dependency upon EGFR signalling, for example in certain tumours harbouring activating mutations in EGFR. RET kinase has also been identified as a third target for ZD6474. This review summarises preclinical studies with this unique agent and considers its future direction in cancer treatment.

Lymphangiogenic growth factors as markers of tumor metastasis

Understanding the complex process of tumor metastasis is a problem which has challenged both clinician and scientist for well over 100 years. Defining molecular markers which reflect the metastatic potential of a tumor has also proved elusive. Recently, members of the vascular endothelial growth factor (VEGF) family of glycoproteins have been demonstrated to be potent mediators of both blood vessel and lymphatic vessel formation in the context of tumor biology. Experimental studies in animal models combined with extensive clinicopathological data provide a compelling case indicating that members of the VEGF family play a key role in the formation of metastases in a broad range of solid tumors. The question of whether VEGF signaling pathways can now serve as therapeutic targets alone, or in combination with other forms of anti-cancer agents, needs to be addressed.

Relationship between VEGF-C expression and lymph node metastasis and prognosis in large intestinal carcinoma

AIM: To explore the expression of endothelial growth factors C (VEGF-C) in large intestine carcinoma, and its relationship to clinicopathological features and prognosis.

METHODS: The expression of VEGF-C in 96 cases of large intestine carcinoma was detected by SP immunohistochemical technique and its relationship to clinicopathological features and prognosis were analysed.

RESULTS: The expression of VEGF-C was significantly higher in intratumoral tissue than that in normal mucosa(42/96 vs 19/96, P < 0.01). VEGF-C positive expression was significantly correlated with tumor differentiation, Dukes' stage, lymph node metastasis and prognosis in 96 cases of large intestine carcinoma (P < 0.01 or P < 0.05), but its relationship to age and gender of patient, size, site and depth of invasion of tumour and organ metastasis was not found (P>0.05). The expression of VEGF-C in metastatic lymph nodes was fairly consistent with that in the primary tumour (P < 0.01).

CONCLUSION: The overexpression of VEGF-C in large intestine carcinoma can develop lymph node metastasis by inducing lymphangiogenesis, and it may serve as one prognostic factor and guide the treatment.

Crosstalk between angiogenesis and lymphangiogenesis in tumor progression

Extensive studies have identified reliable markers of lymphatic endothelial cells, and mechanisms and molecules that regulate development and growth of the lymphatic vessels. Vascular endothelial growth factors (VEGF)-C and VEGF-D, and their cognate receptor tyrosine kinase, VEGF receptor-3 (VEGFR-3), are critical regulators of lymphangiogenesis. By binding to its endothelial cell surface receptors VEGFR-1 and VEGFR-2, VEGF-A mediates vascular leakage, endothelial proliferation and migration. Angiopoietin-2 (Ang-2) is expressed at sites of blood vessel remodeling and invasion, and factors that induce angiogenesis in vivo, such as VEGF-A, upregulate Ang-2 in endothelial cells. In this review, we summarize the literature concerning the crosstalk between angiogenesis and lymphangiogenesis in tumor progression, that is, involvement of VEGF-C, VEGF-D and VEGFR-3 in angiogenesis, and the role played by VEGF-A and Ang-2 in lymphangiogenesis, respectively.

Lymphatic density and metastatic spread in human malignant melanoma

Malignant melanoma (MM), the most common cause of skin cancer deaths, metastasises to regional lymph nodes. In animal models of other cancers, lymphatic growth is associated with metastasis. To assess if lymphatic density (LD) was increased in human MM, and its association with metastasis, we measured LD inside and around archival MM samples (MM, n=21), and compared them with normal dermis (n=11), basal cell carcinoma (BCC, n=6) and Merkel cell carcinoma (MCC), a skin tumour thought to metastasise through a vascular route (MCC, n=6). Lymphatic capillary density (mm⁻²), as determined by immunohistochemical staining with the lymphatic specific marker LYVE-1, was significantly increased around MM (10.0±2.5 mm⁻²) compared with normal dermis (2.4±0.9 mm⁻²), BCC (3.0±0.9 mm⁻²) and MCC (2.4±1.4 mm⁻²) (P<0.0001). There was a small decrease in LD inside MM (1.1±0.7 mm⁻²) compared with normal dermis, but a highly significant decrease in BCC (0.14±0.13) and MCC (0.12±2.4) (P<0.01 Kruskal–Wallis). Astonishingly, LD discriminated between melanomas that subsequently metastasised (12.8±1.6 mm⁻²) and those that did not (5.4±1.1 mm⁻², P<0.01, Mann–Whitney). Lymphatic invasion by tumour cells was seen mainly in MM that metastasised (70% compared with 12% not metastasising, P<0.05 Fisher's Exact test). The results show that LD was increased around MMs, and that LD and tumour cell invasion of lymphatics may help to predict metastasis. To this end, a prognostic index was calculated using LD, lymphatic invasion and thickness that clearly discriminated metastatic from nonmetastatic tumours.