The role of vascular endothelial growth factor (VEGF) in oral dysplasia and oral squamous cell carcinoma

A better understanding of oral cancer pathogenesis is essential to improving patient prognosis and treatment modalities. Research has shown a significant increase in vascularity during the transition from normal oral mucosa, through differing degrees of dysplasia, to invasive carcinoma. A close association between tumour angiogenesis and tumour progression to late oral squamous cell carcinoma has also been reported. Vascular endothelial growth factor (VEGF) acts to induce endothelial proliferation, migration and specialisation in new and developing vascular beds. VEGF is also a promoter of angiogenesis in many tumour types, and has therefore been subject to numerous studies in oral dysplasia and squamous cell carcinomas. The contribution of VEGF to the development of oral dysplasia and invasive carcinomas is currently disputed due to conflicting results within the literature. More research is required before VEGF technology can be used to improve the diagnosis, prognosis and treatment of sufferers.     

Serum vascular endothelial growth factor (VEGF), a prognostic indicator in sarcoma and carcinoma patients

Tumor growth and the development of metastases are dependent on the local formation of new blood vessels. A major role in the induction of angiogenesis has been assigned to vascular endothelial growth factor (VEGF), a tumor cell-derived endothelium-specific mitogen. We studied whether blood levels of VEGF are increased in sarcoma and carcinoma patients. In addition, we tested whether data from measurements of serum VEGF are of prognostic value with respect to tumor remission during chemotherapy courses of sarcoma patients. First, we measured the concentration of VEGF in the sera of 60 normal volunteers and of 25 untreated patients suffering from solid tumors (13 sarcomas, 12 carcinomas). Second, we studied the level of serum VEGF in 9 tumor patients during 4 courses of ICE-chemotherapy (ifosfamide, carboplatin, etoposide). VEGF was measured by enzyme-linked immunoassay. The concentrations of serum VEGF were significantly higher (P <0.0001) in untreated sarcoma (933+/-132 pg/ml) and carcinoma (1,257+/-169 pg/ml) patients compared to those of normal subjects (239+/-21 pg/ml). The concentration of VEGF was roughly proportional to the tumor mass. A significant fall in serum VEGF occurred in the 6 patients who responded to chemotherapy with tumor remission but not in the patient who were resistant. The concentration of serum VEGF is an indicator of tumor growth in sarcoma and carcinoma patients and thus of prognostic value. Serum VEGF measurements may be clinically useful for monitoring tumor regression in sarcoma patients undergoing chemotherapy.     

Blockage of vascular endothelial growth factor (VEGF) reduces experimental pleurodesis

Background and objective

Chemical pleurodesis controls recurrent malignant pleural effusion. The mechanism that determines pleural symphysis involves the action of vascular endothelial growth factor (VEGF). We assessed the influence of the anti-VEGF antibody (bevacizumab) on pleurodesis induced by talc or silver nitrate and analyzed the temporal development of pleural angiogenesis.

Methods

Sixty New Zealand rabbits received intrapleural injection (2 mL) of talc (400 mg/kg) or 0.5% silver nitrate. In each group, half of the animals received an intravenous injection of bevacizumab 30 min before the sclerosing agent. Five animals from each group were euthanized 7, 14, or 28 days after the procedure. Adhesions and inflammation (scores: 0-4), thickness (μm), vascular density (vessels/field), and collagen fibers (μm²) were evaluated in the visceral pleura.

Results

Antibody anti-VEGF interferes in pleurodesis induced by talc or silver nitrate. Pleural inflammation was discreet with no difference between the groups, regardless the anti-VEGF treatment. Concerning the vascular density of the visceral pleura, a smaller number of neoformed vessels was noted in the animals that received bevacizumab. In the animals receiving silver nitrate, the decrement in adhesions and vascular density was associated with reduced thick and thin collagen fibers, resulting in less pleural thickness.

Conclusion

The anti-VEGF antibody inhibits adhesions between pleural layers. Despite being an experimental study in animals with normal pleura, the results call attention to a likely lack of success in pleurodesis when VEGF blockers are used.     

Immunohistochemical evaluation of vascular endothelial growth factor (VEGF) in colorectal carcinoma

BACKGROUND: Vascular endothelial growth factor (VEGF) is one of the most important proangiogenic factors over-expressed in many human cancers and is usually associated with an unfavorable outcome. This work was planned to assess VEGF and microvessel density (MVD) in colorectal carcinoma (CRC) and to correlate them with the available clinicopathological parameters. MATERIAL AND METHODS: Ten normal colonic mucosa, 21 adenoma and 70 CRC cases were examined by immunohistochemical staining using anti-VEGF antibody. RESULTS: Eighty-one percent (81%) of adenoma and 78.6% of CRC cases showed VEGF immunoreactivity; however, the intensity of staining was significantly in favour of malignant cases (p=0.032). VEGF immunostaining in CRC was correlated with low grade (p=0.009), early stage either by Dukes' system (p=0.03) or TNM stage (p=0.03), negative nodal status (p=0.04) and high mast cell count (p=0.04). MVD assessed by Haematoxylin and Eosin staining was associated with dense inflammatory response (p=0.003) and high mast cell count (p=0.006). CONCLUSIONS: VEGF could be an early carcinogenic factor in CRC that declines with its progression. Inflammatory cells including mast cells could play a role in CRC angiogenesis.     

The significance of circulating vascular endothelial growth factor (VEGF) protein in gastric cancer

We examined the vascular endothelial growth factor (VEGF) levels in peripheral blood and drainage vein (plasma and serum), and then these were compared with local VEGF expression from gastric cancer. Peripheral blood plasma VEGF levels was increased in the patients with venous invasion, and moderately correlated with the number and ratio of lymph nodes with metastasis. Local VEGF expression was correlated significantly with tumor size, advanced stage and lymph node metastasis, but not correlated with peripheral VEGF levels. The level of plasma VEGF in peripheral veins is one of the sensitive markers of the status of gastric cancer.     

The clinical toxicity profile of vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor (VEGFR) targeting angiogenesis inhibitors; a review

Clinical experience with vascular endothelial growth factor (VEGF) and vascular endothelial growth factor receptor (VEGFR) targeting angiogenesis inhibitors is rapidly increasing, and some compounds have already been approved for regular anticancer treatment.Apart from their activity, much attention has been focussed on the clinical toxicity profile of these compounds.This review describes the most frequently occurring side-effects of both antibodies and tyrosine kinase inhibitors and discusses some of the underlying mechanisms. Some practical guidelines for treatment of the side-effects are given.     

Treatment of AIDS-related Kaposi's sarcoma

Kaposi's sarcoma (KS) is the most common malignancy seen in association with AIDS. Important epidemiologic trends in the occurrence of AIDS-associated Kaposi's sarcoma (AIDS-KS) have been identified, and the molecular processes associated with the development of KS are being studied intensively. It is hoped that these studies will ultimately lead to an understanding of the etiology of the disease and to a rational approach to therapy. Treatment with conventional chemotherapy, radiation therapy, biologic therapy, and various local treatment modalities is effective for palliation of clinical problems associated with AIDS-KS, although the toxicities of these approaches may be problematic. Therapy for AIDS-KS must be individualized, with appropriate consideration given to the patient's overall clinical and immunologic status.     

Use of soluble recombinant decoy receptor vascular endothelial growth factor trap (VEGF Trap) to inhibit vascular endothelial growth factor activity

Primary tumors and metastases require blood vessel formation to support their continued growth and eventual metastasis. They use existing vasculature during initial growth but eventually must orchestrate the development and maintenance of new vessels--a process termed angiogenesis--to grow beyond a small size and spread. Angiogenesis is regulated by a number of soluble factors, the relative proportions of which can exacerbate or inhibit the process. Vascular endothelial growth factor (VEGF) is a potent stimulator of angiogenesis, produced by the majority of human solid tumors. Inhibitors of VEGF might have an impact on the growth and metastasis of these cancers. The relevance of this strategy to the treatment of colorectal cancer was first successfully demonstrated in human clinical trials using a monoclonal antibody against VEGF. A potent antiangiogenic soluble recombinant decoy, VEGF Trap is a protein constructed from VEGF receptor-binding domains linked to an immunoglobulin G(1) constant region. It possesses an affinity for VEGF that is significantly higher than that of the monoclonal antibody. VEGF Trap has demonstrated marked efficacy in halting angiogenesis and shrinking tumors in preclinical animal models and is currently being studied in phase I clinical trials in humans with advanced solid malignancies.     

血管内皮生长因子抗体对肿瘤转移的抑制作用

目的探讨阻断血管内皮生长因子（ｖａｓｃｕｌａｒｅｎｄｏｔｈｅｌｉａｌｇｒｏｗｔｈｆａｃｔｏｒ,ＶＥＧＦ）是否可以抑制肿瘤的转移。方法应用ＩＶＴＡ２ＭＡ－８９１津白Ⅱ小鼠自发乳腺癌模型进行抗肿瘤转移的研究,此模型伴有高自发肺转移。结果Ｎｏｒｔｈｅｒｎ杂交及免疫组化证实,该乳腺癌原发灶及肺转移灶均可表达ＶＥＧＦ,且以后者为高。接种肿瘤后第９天,以ＶＥＧＦ抗体处理荷瘤小鼠,可明显抑制原发肿瘤的生长（４４．０％,Ｐ＜０．０５）,而对肺转移灶数目及转移灶大小的抑制率分别达７３．０％和８３．７％。结论ＶＥＧＦ抗体对肿瘤转移的抑制有潜在的应用价值。     

Management of AIDS-related Kaposi's sarcoma

The advent of highly active antiretroviral therapy (HAART) has lead to a substantial reduction in the prevalence, morbidity, and mortality associated with AIDS-related Kaposi's sarcoma. Similarly, concomitant advances in chemotherapy and supportive-care protocols have allowed for Kaposi's sarcoma to be managed more effectively in comparison with the pre-HAART era. Furthermore, developments in our understanding of the pathogenesis of Kaposi's sarcoma have identified several molecular targets that can potentially provide new therapeutic strategies. This Review discusses the role of conventional chemotherapeutic and immunomodulatory agents in the treatment of Kaposi's sarcoma and summarises the current status and future prospects of novel molecularly targeted agents in the treatment of this disease.     

Expression of vascular endothelial growth factor (VEGF) and VEGF receptors in tumor angiogenesis and malignancies

Angiogenesis is a process by which new blood vessels are formed from preexisting vessels. New blood vessel formation by angiogenesis involves the degradation of extra-cellular matrix combined with sprouting and migration of endothelial cells from preexisting capillaries. Solid tumors consist of several components, including normal and stromal cells, extracellular matrix, and vasculature. To grow and metastasize, tumors must stimulate the development of new vasculature through angiogenesis. Vascular endothelial growth factor (VEGF) is a potent angiogenic peptide with biologic effects that include regulation of hematopoietic stem cell development, extracellular matrix remodeling, and inflammatory cytokine regeneration. VEGF is both a vascular growth factor and a vascular permeability factor. Its expression can upregulate several proangiogenic and prometa-static molecules. As a central mediator of angiogenesis, VEGF has emerged as an important target for antiangiogenic therapy. In this review, the authors describe the essential characteristics of VEGF and the VEGF family of ligands and their receptors. They also provide an overview of the central role of VEGF in physiologic and pathologic angiogenesis, directly or indirectly. This review sheds light on the importance of VEGF-targeted antiangiogenic therapy based on the monoclonal antibodies against VEGF, small interfering RNA, and therapy directed against VEGF-VEGFR kinase. It also gives a brief overview of the natural products or dietary compounds that could be used as antiangiogenic agents. Therapeutic inhibition of vessel formation could be best suited to preventive strategies aimed at the suppression of angiogenesis in primary tumors in subjects at risk or of micrometastases after surgical removal of primary tumor.     

Elevated vascular endothelial growth factor (VEGF) serum levels in idiopathic myelofibrosis.

An increase of angiogenesis has been shown in idiopathic myelofibrosis with myeloid metaplasia (MMM) by microvessel density count method but evaluation of circulating angiogenic factors is still incomplete. In 31 patients affected by MMM and in 12 healthy subjects we evaluated the serum levels of VEGF (vascular endothelial growth factor) and correlated VEGF with clinical and laboratory features of disease. We found that MMM patients had circulating VEGF concentrations much higher than controls (Median 1208 ng/ml vs 138 ng/ml, P < 0.0001). No correlation was found between VEGF and Hb, WBC, PLT, LDH, creatinine, bone marrow cellularity, fibrosis, splenomegaly, hepatomegaly, and therapy. However, in the subgroup of patients with a normal or low VEGF concentration, a direct correlation between VEGF and platelet count (r = 0.90, P = 0.002) was detected. Moreover, patients with a platelet count < 300 x 10(9)/l had VEGF serum levels lower than patients with a higher PLT count (median VEGF 864 vs 1557 pg/ml, P = 0.001). In six patients and in eight controls we also had the opportunity to measure VEGF in the plasma and we calculated that VEGF concentration was much higher in platelet-rich than in platelet-poor plasma and that platetets of MMM patients contained four times more VEGF than those of healthy controls. These results indicate that VEGF is overproduced in MMM, thus confirming an increased angiogenic activity. Platelets are probably a major source of VEGF in MMM but not the only one.     

The role of vascular endothelial growth factor (VEGF) in tumor angiogenesis and early clinical development of VEGF-receptor kinase inhibitors

Angiogenesis, or the formation of new blood vessels from preexisting vasculature, plays a major role in tumor growth and metastasis formation. Therefore, inhibiting tumor angiogenesis may be a promising therapeutic strategy. Paracrine stimuli from tumor cells are the main promoters of angiogenesis. They activate endothelial cells to proliferate and migrate, subsequently resulting in new tube formation and blood flow. This complex process involves numerous biological activities. Vascular endothelial growth factor (VEGF) is a potent and specific angiogenic factor. Originally identified for its ability to induce vascular permeability and stimulate endothelial cell growth, VEGF is now known to be a key requirement for tumor growth. Currently, three high-affinity tyrosine kinase receptors for VEGF have been identified, of which VEGF receptor (VEGFR)-Flk-1/KDR (VEGFR-2) is exclusively expressed in vascular endothelial cells. Because the VEGFR-2 system is a dominant signal-transduction pathway in regulating tumor angiogenesis, specific inhibitors of this pathway inhibit metastases, microvessel formation, and tumor-cell proliferation. Induction of apoptosis in tumor cells and endothelial cells has also been observed. The clinical importance of VEGF for tumor growth is supported by the fact that most tumors produce VEGF and that the inhibition of VEGF-induced angiogenesis significantly inhibits tumor growth in vivo. In this review, we discuss the biologic role of VEGF and the therapeutic options for inhibiting VEGF in cancer patients.     

血管内皮生长因子在子宫颈癌组织中的表达及意义

目的　探讨血管内皮生长因子 (VEGF ,VEGFmRNA)在子宫颈癌组织中的表达及意义。方法　采用免疫组织化学技术SP法及原位杂交方法检测 33例宫颈癌 ,其中鳞癌 2 0例 ,腺癌 13例及 10例正常宫颈组织中VEGF及VEGFmRNA的表达情况。结果　宫颈癌组织切片中VEGF及VEGFmRNA皆有活跃表达。正常宫颈组织中VEGFmRNA呈阴性表达 ,VEGF蛋白可见弱阳性表达 ,两组比较差异有显著性 (P <0 .0 5 ) ;宫颈癌组织切片中的VEGFmRNA的表达与宫颈癌病理类型比较差异有显著性 (P <0 .0 5 ) ;而与宫颈癌临床分期及病理分化程度比较差异无显著性 (P >0 .0 5 )。结论　VEGF及VEGFmRNA的阳性表达在子宫颈癌的发生 ,发展中可能有着重要的意义。VEGF的检测对判断宫颈癌的病理类型有一定的临床价值。