Chronic alcohol consumption stimulates VEGF expression, tumor angiogenesis and progression of melanoma in mice

The mechanisms of alcohol-induced cancer in humans are unclear. We used the immunocompetent mice implanted with B16F10 cells to evaluate the effects of physiologically relevant EtOH intake on tumor growth and angiogenesis of melanoma. Six-wk-old male mice (C57BL/6J) were given 1% EtOH in drinking water for 12-hrs during the night which was then replaced with regular water during the remaining 12-hrs each day for 4 wks (n = 10). The control mice received regular drinking water only. In the second week, all mice were inoculated subcutaneously on the right proximal dorsal with 5 x 10(5) B16F10 cells. In the end, the tumors were isolated for measuring tumor size, average microvascular density (AMVD) using CD31 immunohistochemistry, and the expression of VEGF and its receptor (Flt-1) using Northern blot, ELISA, and immunohistochemistry. EtOH intake caused a 2.16-fold increase in tumor weight over the control (4.81 +/- 0.39 vs. 2.23 +/- 0.48 g; n = 10; p = 0.003), a 2.02-fold increase in AMVD (60.63 +/- 5.56 vs. 30.01 +/- 7.41/mm(2); p = 0.0014), and a significant increase in VEGF mRNA and protein expression plus Flt-1 protein levels in melanoma compared to the control group (p < 0.01). These results suggest that progression of melanoma growth and angiogenesis may be mediated by upregulation of VEGF and Flt-1, especially under the influence of EtOH.     

VEGF,bFGF and EGF in the angiogenesis of human melanoma xenografts

Vascular endothelial growth factor (VEGF) is a major inducer of angiogenesis in tumors. Basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) have both been shown to interact with VEGF. The involvement of VEGF, bFGF and EGF in melanoma angiogenesis was investigated here. Four human melanoma cell lines (A-07, D-12, R-18, U-25) were included in the study. Angiogenesis was quantified by scoring of tumor-oriented capillaries following intradermal cell inoculation in BALB/c nu/nu mice. VEGF, bFGF and EGF expression and secretion were investigated by Western blotting and enzyme-linked immunosorbent assay, respectively. Immunohistochemistry of xenografts grown intradermally was used to reveal VEGF and bFGF localization in vivo. The rate of angiogenesis differed substantially among the melanoma lines; the sequence from a high to low rate of angiogenesis was: A-07, D-12, R-18, U-25. A-07, which induced the highest rate of angiogenesis, showed a higher rate of VEGF secretion, stronger VEGF staining by immunohistochemistry and higher bFGF expression than the other lines. U-25, which induced the lowest rate of angiogenesis, showed a higher rate of VEGF secretion than D-12 and R-18. A-07 was the only line that showed detectable bFGF secretion, and R-18 was the only line that showed detectable EGF secretion. VEGF is probably important in the angiogenesis of melanomas. However, heterogeneity in rate of angiogenesis among melanomas cannot be attributed to heterogeneity in rate of secretion of VEGF, bFGF and/or EGF only. Int. J. Cancer 76:836–841, 1998.© 1998 Wiley-Liss, Inc.     

Myeloid-derived suppressor cells contribute to A2B adenosine receptor-induced VEGF production and angiogenesis in a mouse melanoma model

Vascular endothelial growth factor (VEGF) is an angiogenic factor critically involved in tumor progression. Adenosine A2B receptor plays a pivotal role in promoting tumor growth. The aim of this study was to investigate the role of myeloid-derived suppressor cells (MDSCs) in the pro-angiogenic effects of A2B and to determine whether A2B blockade could enhance the effectiveness of anti-VEGF treatment. Mice treated with Bay60-6583, a selective A2B receptor agonist, showed enhanced tumor VEGF-A expression and vessel density. This effect was associated with accelerated tumor growth, which could be reversed with anti-VEGF treatment. Bay60-6583 increased the accumulation of tumor CD11b+Gr1+ cells. Depletion of MDSCs in mice significantly reduced A2B-induced VEGF production. However, A2B receptor stimulation did not directly regulate VEGF expression in isolated tumor myeloid cells. Mechanistically, Bay60-6583-treated melanoma tissues showed increased STAT3 activation. Inhibition of STAT3 significantly decreased the pro-tumor activity of Bay60-6583 and reduced tumor VEGF expression.Pharmacological blockade of A2B receptor with PSB1115 significantly reduced tumor growth by inhibiting tumor angiogenesis and increasing T cells numbers within the tumor microenvironment. These effects are, at least in part, dependent on impaired tumor accumulation of Gr1+ cells upon A2B receptor blockade. PSB1115 increased the effectiveness of anti-VEGF treatment.     

Cell adhesion receptor expression during melanoma progression and metastasis

Summary Many steps in melanoma metastasis involve cell-cell or cell-matrix adhesive interactions. The surface molecules which mediate these processes therefore play an important role in regulating melanoma dissemination and their level of expression may alter during the course of tumor progression. Human melanocyte strains and melanoma cell lines have been characterised with regard to levels of cell surface receptors of the integrin family. Increased amounts of at least two integrins, VLA-4 (₄₁) and VnR (_V3), appeared to correlate with progression in this tumor, type. A novel VnR composed of an _V1 association has been observed in one melanoma cell line and there is the possibility that heterogeneity of integrin composition could affect biological behavior of these tumors.CD44, a cell surface glycoprotein which functions as the major receptor for hyaluronate, is another molecule whose expression increases in transformed cells of the melanocytic lineage. Iterative sorting on the FACS for stable variants, of both human and murine melanomas, expressing low and high levels of CD44 established that lack of expression of this molecule correlated with impaired ability to form pulmonary tumor nodules subsequent to i.v. injection into appropriate recipient mice. These findings illustrate that an understanding of the regulation of melanoma adhesion receptors could provide insights into the process of tumor spread.     

Up-regulation of ephrin-A1 during melanoma progression.

Ephrin-A1, formerly called B61, is a new melanoma growth factor; it is angiogenic and chemoattractant for endothelial cells. EPH-A2, or ECK (a receptor for ephrin-A1), is ectopically expressed in most melanoma cell lines; the pathology where this expression is first manifested and the possible role of the receptor in tumor progression are unknown. To determine these, we studied the expression of this ligand and receptor in biopsies of benign and malignant melanocytic lesions. EPH-A2 was not detected in normal melanocytes, benign compound nevi or advanced melanomas, though it was found in 2 of 9 biopsies of malignant melanoma in situ. Ephrin-A1 was present in occasional early lesions and in advanced primary melanomas (43%) and metastatic melanomas (67%). Expression of ephrin-A1 was induced in melanoma cells by pro-inflammatory cytokines. Our findings are consistent with 2 possible roles for ephrin-A1 in melanoma development: it may promote melanocytic cell growth or survival and induce vascularization in advanced melanomas. Both effects may be potentiated by inflammatory responses. Our data are consistent with earlier observations that an inflammatory infiltrate is associated with poor prognosis in thin primary melanomas.     

Oct-3/4 promotes tumor angiogenesis through VEGF production in glioblastoma

Brain Tumor Pathology - Accumulating evidence shows that the expression level of Oct-3/4, a self-renewal regulator in stem cells, is positively correlated with the progression of various solid...     

Tumor progression and angiogenesis]

Vascular endothelial growth factor (VEGF) plays a central role in angiogenesis, which underlies tumor progressions such as metastasis. A unique biological feature is that VEGF, mainly produced by malignant cells, hits seemingly non-malignant endothelial cells of host origin. The expression level of VEGF or its receptors appears to be regulated by intrinsic factors such as genetic alterations as well as by extrinsic factors such as pO2 and cytokines. Receptor signals result in coordinated regulation of molecules responsible for growth, differentiation, matrix degradation, migration, adhesion, coagulation, permeability and so forth.     

Administration of VEGF receptor tyrosine kinase inhibitor increases VEGF production causing angiogenesis in human small-cell lung cancer xenografts

Angiogenesis is mediated mainly by vascular endothelial growth factor (VEGF), and VEGF causes rapid growth in cancers, including human small-cell lung cancer (SCLC). The anti-angiogenic strategy of treating cancer using VEGF receptor (VEGFR) inhibition is currently of great interest. We tested the effects of the VEGFR2 tyrosine kinase inhibitor (TKI) vandetanib on the proliferation of two kinds of SCLC cell lines: SBC-1 cells, with detectable VEGFR2 expression and MS-1-L cells, without detectable VEGFR2 expression. To evaluate the anti-tumor and anti-angiogenic effects of vandetanib in vivo, we grafted SBC-1 and MS-1-L cells into mice. After a 3-week treatment, we measured the tumor size and histologically evaluated necrosis and apoptosis using H&E and TUNEL staining, respectively. The microvessels in the xenografts were also quantified by immunostaining of CD31. Vandetanib did not affect the proliferation of SBC-1 cells, but stimulated the growth of MS-1-L cells. In the SCLC xenograft model, vandetanib inhibited growth and tumor angiogenesis in a dose-dependent manner in SBC-1 xenografts. Vandetanib inhibited the growth of MS-1-L xenografts at a low dose (<12.5 mg/kg/day), but it did not affect tumor size or change microvessel counts at a higher dose. Interestingly, secretion of VEGF increased significantly in the MS-1-L cell line in the presence of a high dose of vandetanib in vitro. The effects of vandetanib on tumor angiogenesis were different in SBC-1 and MS-1-L cell lines. Production of angiogenic factors such as VEGF by the tumor potentially stimulates tumor angiogenesis and results in the acquisition of resistance to VEGFR TKI.     

血管内皮生长因子和Notch信号通路与肿瘤血管生成

血管内皮生长因子(VEGF)和Notch信号通路是血管发育及肿瘤血管生成的重要机制.阻断VEGF可抑制肿瘤生长和血管生成.Notch能抑制内皮形成尖端细胞,减少血管生成.实验证明,两条通路相互作用,联合阻断VEGF和Notch信号通路可协同抑制肿瘤生长.对VEGF和Notch通路的研究,将为肿瘤临床治疗提供新的方法.     

WNT5A expression increases during melanoma progression and correlates with outcome

PURPOSE: Wnt ligands play a major role in development and are important in cancer. Expression microarray analysis correlates one member of this family, WNT5A, to a subclass of melanomas with increased motility and invasion. There are no large studies of clinical samples primarily addressing the importance of WNT5A in melanoma progression or outcome. Therefore, this study aimed to assess the protein expression of WNT5A during melanoma progression and its effect on outcome. EXPERIMENTAL DESIGN: Expression of WNT5A was determined in a series of 59 primary melanomas with matched metastases. To provide a benchmark of progression against which to assess WNT5A, expression of p16(ink4a) was analyzed, as this has been previously well documented in melanoma. The effect of WNT5A protein expression on outcome was assessed in 102 melanomas. RESULTS: Cytoplasmic WNT5A showed a trend of increasing expression with melanoma progression (P = 0.013), whereas there was diminishing p16(ink4a) expression (P = 0.006). Nevi showed relatively strong WNT5A expression. Strong cytoplasmic WNT5A was an independent risk factor for reduced metastasis-free and overall survival in multivariate analysis (P = 0.001 and 0.003, respectively). CONCLUSION: Cytoplasmic WNT5A increases with melanoma progression and strong expression is associated with poor outcome.     

p73 Overexpression increases VEGF and reduces thrombospondin-1 production: implications for tumor angiogenesis.

Tumor neovascularization is controlled by a balance between positive and negative effectors, whose production can be regulated by oncogenes and tumor suppressor genes. The aim of this study was to investigate whether the angiogenic potential of tumors could also be controlled by p73, a gene homologous to the tumor suppressor p53, whose involvement in tumor angiogenesis is known. We have studied the production of proangiogenic (VEGF, FGF-2, PIGF and PDGF) and antiangiogenic (TSP-1) factors in two p73 overexpressing clones obtained from the human ovarian carcinoma cells A2780. TSP-1 was downregulated in both clones compared to mock transfected cells, both at mRNA and protein level. Conversely, both clones showed an increased production of VEGF mRNA and protein. For both TSP-1 and VEGF, regulation of expression was partially due to modulation of the promoter activity, and was dependent on p53 status. Production of the other angiogenic factors FGF-2, PIGF and PDGF-B was also increased in p73 overexpressing clones. The two clones were more angiogenic than parental cells, as shown in vitro by their increased chemotactic activity for endothelial cells, and in vivo by the generation of more vascularized tumors. These findings suggest a potential role of p73 in tumor angiogenesis.     

VEGF and the quest for tumour angiogenesis factors

The ability of tumours to induce new blood-vessel formation has been a major focus of cancer research over the past few decades, and vascular endothelial growth factor (VEGF) is now known to be central to this process. The quest for VEGF and other factors that promote tumour angiogenesis was initiated many decades ago, and a long and complicated path has led to the development of inhibitors of these molecules as anticancer agents. How did this field begin, and how have we arrived at our present understanding of the role of VEGF in tumour progression.     

Transforming growth factor-beta and Ras regulate the VEGF/VEGF-receptor system during tumor angiogenesis.

The formation of new microvasculature by capillary sprouting, or angiogenesis, is a prerequisite for solid tumor growth. The genetic alterations required to activate the angiogenic program in tumor angiogenesis are still only vaguely known, but dominantly acting oncoproteins may have a much greater impact than previously realized. Here we have studied the consequences of oncogenic transformation on tumor angiogenesis in a mouse mammary carcinoma model. We provide evidence that the expression of vascular endothelial growth factor (VEGF) and of the VEGF receptor-2 (Flk-1), a signaling system centrally involved in tumor angiogenesis, occurs efficiently in tumors formed by Ras-transformed mammary epithelial cells and that both TGF-beta1 and hypoxia are potent inducers of VEGF expression in these cells. VEGF induction in the tumor periphery is mainly triggered by TGF-beta1, whereas VEGF expression in perinecrotic areas is regulated by both hypoxia and TGF-beta1. As the Ras-transformed tumor cells convert into migrating, fibroblastoid cells that start to produce TGF-beta during tumor progression, the TGF-beta effect on VEGF expression becomes propagated throughout the tumor tissue. Thus, in progressed tumors, areas of TGF-beta1 activation and hypoxia may overlap and hence cooperate to induce VEGF expression and angiogenesis. Nevertheless, the overexpression of VEGF in non-Ras-transformed mouse mammary epithelial cells was not sufficient to promote vascularization in vivo. Based on these findings, we conclude that amongst the multiple mutations that render a normal cell tumorigenic, oncogenic Ras is a major player that in conjunction with the tumor's micro-environment sets the stage for tumor cell invasion and angiogenesis.     

Human melanoma: Development and progression

Clinical and histopathological evidence suggests that melanoma develops in a sequence of steps, progressing from benign proliferative lesions, to primary melanomas that do not show evidence for metastasis, to invasive primary lesions, and to metastases. This review focuses on the experimental studies examining the phenotypic characteristics of cultured primary melanoma cells as they relate to cells from non-malignant nevi and metastases. Genetic, biologic, and immunologic criteria have been established to distinguish melanocytes from different steps of tumor development. These include non-random chromosomal abnormalities, expression of melanocyte-and melanoma-specific antigens, requirements for exogenous growth factors, production of endogenous growth factors, and expression of receptors for growth factors. The transformation of melanocytes and nevus cells with viral oncogenes has facilitated studies on the malignant phenotype. Variants have been developed through successive selections from primary melanoma cell populations that have one or several characteristics of metastatic cells. The study of melanocytes isolated from various stages of tumor development and the generation of cell variants with specific properties should enable a long-term search for the molecular mechanisms of melanoma development and progression.     

Tissue factor,angiogenesis and tumour progression

Tissue factor, the primary initiator of the coagulation cascade, maintains vascular integrity in response to injury. It is now recognised that, in addition to the role as a procoagulant activator, tissue factor participates in many tumour-related processes that contribute to malignant disease progression. The present review details the recent evidence supporting a role for tissue factor in tumour haemostasis, angiogenesis, metastasis and malignant cell survival. Furthermore, future research directions are discussed that may enhance our understanding of the role and regulation of this protein, which could ultimately lead to the innovative design and development of new anticancer therapies.     

The elastin connection and melanoma progression

Matrikines, i.e. matrix fragments with cytokine-like properties, have been ascribed a major role in regulating tumour progression. The invasive front of melanoma is characterised by intense fragmentation of dermal elastic fibres. Elastase-mediated elastolysis liberates elastin fragments, i.e. elastokines, that stimulate several aspects of melanoma progression such as to enhance melanoma cell invasion through type I collagen or increase angiogenesis. Induced-membrane-type 1 metalloprotease (MT1-MMP) expression following elastin receptor (S-Gal) occupancy by elastokines is responsible for those biological activities. Several matrix-derived peptides with a GXXPG consensus sequence adopting a type VIII beta-turn conformation were as potent as elastokines in promoting angiogenesis in a Matrigel assay, and galectin-3 also contains several similar repeats within its N-terminal domain. We propose that S-Gal might constitute a novel therapeutic target for controlling melanoma progression.