Vascular Endothelial Growth Factor Concentrations in Body Cavity Effusions in Dogs

Serum vascular endothelial growth factor in dogs with various proliferative diseases

Angiogenesis plays an important role in the proliferation and metastasis mechanisms of malignant tumors. Vascular endothelial growth factor (VEGF), a group of cytokines that contribute to angiogenesis and vasculogenesis. This study aimed to investigate the serum VEGF-A concentrations in dogs with various proliferative diseases. A total of 202 dogs that were histopathologically diagnosed with proliferative diseases were included in the study. Serum VEGF-A concentrations were measured using enzyme-linked immunosorbent assay. Median serum VEGF-A concentrations in dogs were as follows: healthy dogs, 4 pg/ml [0–21 pg/ml]; hepatocellular carcinoma, 30 pg/ml [0–158 pg/ml, P=<0.001]; hepatocellular adenoma, 32 pg/ml [0–49 pg/ml, P=0.003]; hepatic nodular hyperplasia, 18 pg/ml [0–51 pg/ml, P=0.595]; adrenal pheochromocytoma, 32 pg/ml [0–187 pg/ml, P=<0.001]; adrenocortical carcinoma, 32 pg/ml [3–161 pg/ml, P=0.002]; adrenocortical adenoma, 27 pg/ml [0–106 pg/ml, P=0.005]; colorectal adenocarcinoma, 36 pg/ml [0–75 pg/ml, P=0.002]; colorectal adenoma, 43 pg/ml [0–48 pg/ml, P=0.144]; inflammatory colorectal polyps, 37 pg/ml [0–111 pg/ml, P=<0.001]; pulmonary adenocarcinoma, 35 pg/ml [4–107 pg/ml, P=0.002]; pulmonary histiocytic sarcoma, 35 pg/ml [0–131 pg/ml, P=0.016]; and follicular thyroid carcinoma, 35 pg/ml [0–106 pg/ml, P=0.009]. The serum VEGF-A concentrations were significantly higher in dogs with neoplastic lesions compared to healthy dogs, except for colorectal adenoma. High serum VEGF-A concentrations were observed in dogs with proliferative diseases. The present study suggests that angiogenesis-inhibiting therapy, which targets VEGF-A, may be useful for canine neoplastic diseases.

Canine and feline haemangiosarcoma

INTRODUCTION

Haemangiosarcoma (HSA) is a malignant neoplasm of dogs and cats that is suspected to originate from a pluripotent bone marrow progenitor with a complex and multifactorial pathogenesis.

APPROACH

Pertinent literature was identified, reviewed, and summarized for inclusion in the manuscript.

RESULTS/INTERPRETATION

Dogs are more frequently diagnosed with HSA than cats, and primary sites of this disease include dermal, subcutaneous/intramuscular, and visceral (most commonly the spleen). Dogs and cats with HSA generally have a poor prognosis owing to the rapid and widespread metastasis typically associated with this disease. However, some forms such as cutaneous HSA behave in a less aggressive fashion with improved outcomes. Surgical excision and anthracycline-based chemotherapy remain the mainstays of treatment, although novel treatment modalities are currently under investigation for potential roles in treatment of this disease.

CONCLUSION

This review aims to describe the clinical presentation and progression of the various forms of HSA in dogs and cats as well as to provide a systematic review of the veterinary literature with a focus on the various published treatment options and associated outcomes.

Vascular endothelial growth factor concentrations in the cerebrospinal fluid of dogs with neoplastic or inflammatory central nervous system disorders

Background

Vascular endothelial growth factor (VEGF) is a key molecular driver of angiogenesis and vascular permeability and is expressed by a wide variety of neoplasms. Although blood VEGF concentrations have been quantified in intracranial tumors of dogs, cerebrospinal fluid (CSF) VEGF concentration might be a more sensitive biomarker of disease.

Objective

Concentrations of VEGF in CSF are higher in dogs with central nervous system (CNS) neoplasia compared to those with meningoencephalomyelitis and other neurologic disorders.

Animals

One hundred and twenty‐six client‐owned dogs presented to a veterinary teaching hospital.

Methods

Case‐control study. Cerebrospinal fluid was archived from dogs diagnosed with CNS neoplasia and meningoencephalomyelitis. Control dogs had other neurological disorders or diseases outside of the CNS. A commercially available kit was used to determine VEGF concentrations.

Results

Detectable CSF VEGF concentrations were present in 49/63 (77.8%) neoplastic samples, 22/24 (91.7%) inflammatory samples, and 8/39 (20.5%) control samples. The VEGF concentrations were significantly different between groups (P < .0001), and multiple comparison testing showed that both neoplastic and inflammatory groups had significantly higher concentrations than did controls (P < .05), but did not differ from each other. Gliomas and choroid plexus tumors had significantly higher VEGF concentrations than did the control group (P < .05).

Conclusions and Clinical Importance

Cerebrospinal fluid VEGF concentrations may serve as a marker of neoplastic and inflammatory CNS disorders relative to other conditions.

Vascular Endothelial Growth Factor (VEGF) in Abdominal Fluid in Dogs with Oncological and Non-Oncological Diseases

The vascular endothelial growth factor (VEGF) is a multifunctional cytokine stimulating the growth of vascular endothelial cells, survival and proliferation, inhibiting apoptosis. It is one of the most potent stimulants of vascular permeability. VEGF is found at high levels in inflammatory and tumour-associated pleural and abdominal effusions and is involved in their occurrence. In the present study, the blood plasma and abdominal fluid VEGF levels were assayed in thirty-one client-owned dogs with neoplastic and non-neoplastic diseases by means of enzyme-linked immunosorbent assay (ELISA). The VEGF concentration in abdominal fluid of dogs (n=6) with ascites was 190.70±34.35 pg/ml, in dogs (n=6) with peritonitis: 1449.81±365.42 pg/ml and in dogs (n=9) with tumour-associated effusion: 1993.13±202.56 pg/ml. Blood plasma VEGF of healthy dogs (control group, n=10) was 36.79±5.72 pg/ml, in dogs with ascites: 57.92±2.88 pg/ml, in dogs with peritonitis: 76.98±7.24 pg/ml and in dogs with tumour-associated effusion: 173.50±40.9 pg/ml. There were substantial differences between blood plasma and abdominal fluid VEGF levels.

Does thalidomide prolong survival in dogs with splenic haemangiosarcoma?

OBJECTIVES

To investigate thalidomide as an adjuvant treatment for canine haemangiosarcoma.

MATERIALS AND METHODS

Fifteen dogs with splenic haemangiosarcoma, initially treated by splenectomy, were included. Following recovery from surgery, all dogs received thalidomide continuously until their death. Tumour stage was established using CT scans of the chest and abdomen immediately before starting thalidomide treatment and again three months later. Cause of death was confirmed by post mortem examination.

RESULTS

The median survival time of dogs receiving thalidomide was 172 days (95% confidence interval: 93 to 250 days). Five dogs (33% of the population receiving thalidomide) survived more than 1 year (range 458 to 660 days) after surgery. Dogs with stage 2 disease that received thalidomide also had a longer survival time than dogs with stage 3 disease (median survival time 303 versus 40 days). Of 15 dogs, 13 died from metastatic haemangiosarcoma.

CLINICAL SIGNIFICANCE

Treatment using thalidomide may improve survival of dogs with splenic haemangiosarcoma and should be considered a possible adjuvant therapy.

Serum vascular endothelial growth factor concentration in dogs diagnosed with chronic superficial keratitis

The objective of this study was to measure the vascular endothelial growth factor (VEGF) levels in dogs diagnosed with chronic superficial keratitis (CSK). The study was performed on 25 German shepherds (14 males and 11 females, aged between 3 and 11 years). The VEGF levels were determined in blood serum using commercially available enzyme-linked immunosorbent assay (ELISA; Quantikine Canine VEGF Immunoassay, R&D Systems). The test group of affected German shepherds was subdivided into two subgroups, based on the area of corneal neovascularisation. The first subgroup (9 patients) comprised dogs with neovascularisation observed in 1 to 2 quadrants of the right and left cornea, while the second subgroup (16 patients) comprised dogs with neovascularisation observed in 3 to 4 quadrants of the right and left cornea. The control group comprised 12 clinically healthy German shepherds (7 males and 5 females, aged between 3 and 9 years). The results were then statistically analysed by the Mann-Whitney test. The study indicated that the median serum VEGF concentration in healthy dogs was 14.9 pg/mL. The VEGF level observed in sick German shepherds was elevated (19.5 pg/mL) as compared to the values found in healthy dogs; however, a statistically significant increase in VEGF concentration, as compared to the values observed in healthy dogs, was only noted in the first subgroup, where the median VEGF concentration was 22.0 pg/mL. Elevated serum VEGF concentration was observed in German shepherds diagnosed with CSK. A statistically significant increase in VEGF levels was observed in dogs in the first stage of the disease, i.e. the early stage of neovascularisation.

Breed-predispositions to cancer in pedigree dogs

Cancer is a common problem in dogs and although all breeds of dog and crossbred dogs may be affected, it is notable that some breeds of pedigree dogs appear to be at increased risk of certain types of cancer suggesting underlying genetic predisposition to cancer susceptibility. Although the aetiology of most cancers is likely to be multifactorial, the limited genetic diversity seen in purebred dogs facilitates genetic linkage or association studies on relatively small populations as compared to humans, and by using newly developed resources, genome-wide association studies in dog breeds are proving to be a powerful tool for unravelling complex disorders. This paper will review the literature on canine breed susceptibility to histiocytic sarcoma, osteosarcoma, haemangiosarcoma, mast cell tumours, lymphoma, melanoma, and mammary tumours including the recent advances in knowledge through molecular genetic, cytogenetic, and genome wide association studies.

A review of the pathophysiology, classification, and analysis of canine and feline cavitary effusions

Effusion is the abnormal accumulation of fluid within a body cavity that can result from a variety of disease processes. This article reviews the normal production and resorption of body cavity fluid and the pathophysiology of abnormal fluid accumulation. In addition, classification schemes, differential diagnoses, and currently available diagnostic tests for evaluation of effusions are reviewed.

Expression of vascular endothelial growth factor in tumors and plasma from dogs with primary intracranial neoplasms

OBJECTIVE

To quantitatively evaluate expression of vascular endothelial growth factor (VEGF) in intracranial tumors in dogs and determine whether relationships exist between circulating and intratumoral VEGF concentrations and tumor type and grade.

ANIMALS

27 dogs with primary intracranial neoplasms and 4 unaffected control dogs.

PROCEDURES

Plasma and brain tumor samples were obtained from each dog, and plasma and intratumoral concentrations of VEGF were measured by use of an ELISA.

RESULTS

Dogs with meningiomas (n = 11) were significantly older than dogs with oligodendrogliomas (7) or astrocytomas (9). Measurable VEGF was detected in all tumors, and a significant negative correlation between age and intratumoral VEGF concentration was detected. Age-adjusted comparisons identified significant differences in intratumoral VEGF concentrations among all tumor types; the highest VEGF concentrations were associated with astrocytomas. Within each tumor type, increasing tumor grade was significantly associated with increasing VEGF expression. Plasma VEGF concentrations were detectable in 9 of 27 dogs; the proportion of dogs with astrocytomas and a detectable circulating VEGF concentration (7/9 dogs) was significantly higher than the proportion of dogs with meningiomas (1/11 dogs) or oligodendrogliomas (1/7 dogs) with a detectable circulating VEGF concentration.

CONCLUSIONS AND CLINICAL RELEVANCE

Overexpression of VEGF appears common in canine astrocytomas, oligodendrogliomas, and meningiomas. In the neoplasms examined, intratumoral VEGF concentrations correlated well with tumor malignancy. The VEGF expression patterns paralleled those of analogous human tumors, providing evidence that dogs are a suitable species in which to study angiogenesis and intracranial neoplasia for human application.

Liposome-DNA complexes infused intravenously inhibit tumor angiogenesis and elicit antitumor activity in dogs with soft tissue sarcoma

Intravenous gene delivery using liposome-DNA complexes (LDC) has previously been shown to elicit antitumor activity, but only in rodent tumor models. Therefore, we conducted a study to determine in a large animal spontaneous tumor model whether intravenous infusions of LDC could target gene expression to cutaneous tumor tissues and whether repeated treatments had an effect on tumor growth or angiogenesis. A total of 13 dogs with cutaneous soft tissue sarcomas were enrolled in the study and were randomized to receive a series of 6 weekly infusions of LDC containing either canine endostatin DNA or DNA encoding an irrelevant gene (luciferase). Serial tumor biopsies were obtained to assess transgene expression, tumor microvessel density (MVD), and intratumoral leukocyte inflammatory responses. We found that intravenous infusion of LDC did not result in detectable gene expression in cutaneous tumor tissues. However, two of 13 treated dogs had objective tumor responses and eight dogs had stable disease during the treatment period. In addition, a significant decrease in tumor MVD was noted in six of 12 treated dogs at the completion of six treatments. These results suggest that intravenous infusions of LDC may elicit nonspecific antitumor activity and inhibit tumor angiogenesis.

The influence of fractionated radiation therapy on plasma vascular endothelial growth factor (VEGF) concentration in dogs with spontaneous tumors and its impact on outcome

BACKGROUND AND PURPOSE

Vascular endothelial growth factor (VEGF), a specific pro-angiogenic factor is proposed to be involved in cancer progression and resistance to radiation therapy by promoting angiogenesis and by protecting endothelial cells from radiation induced apoptosis. The aim of this study, was first to assess the influence of ionizing radiation on plasma VEGF concentration in spontaneous canine tumors during fractionated radiation therapy with curative or palliative intent and second to analyze plasma VEGF concentration as predictor for treatment outcome.

PATIENTS AND METHODS

For plasma VEGF analysis a human VEGF enzyme linked immunosorbent assay was used. Sixty dogs with various tumor types were included in this study. Dogs were irradiated with either low dose per fx (3-3.5 Gy per fraction, total dose: 42-49 Gy, group A: curative intent) or high dose per fx (6-8 Gy per fraction, total dose: 24-30 Gy, group B: palliative intent). Blood samples were taken before and after dose application at certain time points during therapy. Follow-up evaluation was performed for analysis of time to treatment failure and survival.

RESULTS

Repeated measures analysis showed no increase of plasma VEGF in dogs treated with fractionated radiation therapy (group A and B). Dichotomizing baseline plasma VEGF into two groups with high and low plasma VEGF, resulted in shorter time to treatment failure in dogs with high plasma VEGF levels (TTF, group A: P=0.038, group B: P=0.041).

CONCLUSIONS

This study demonstrated that dogs with a plasma VEGF level higher than 5 pg/ml had a poorer outcome after radiation therapy. It is therefore, suggested, to use plasma VEGF as predictor for treatment outcome in radiation therapy.

Gene expressions of canine angiopoietin-1 and -2 in normal tissues and spontaneous tumours

The angiopoietin (Ang) family of proteins are central to the regulation of angiogenesis. The purposes of this study were to determine cDNA sequences of canine Ang-1 and Ang-2 and investigate their expressions in normal tissues and spontaneous tumours. The cDNA sequences of canine Ang-1 and Ang-2 were 1,494 and 1,488 bp, and the deduced amino acid sequences were 497 and 495 residues, respectively. The cDNA sequences of canine Ang-1 and Ang-2 showed high homology with those of the other mammalian species. Canine Ang-1 and Ang-2 mRNA were detectable in all 22 normal tissues and spontaneous tumours. Higher mRNA expression level of canine Ang-2 was demonstrated in mammary simple carcinomas, haemangiosarcoma and hepatocellular carcinoma in comparison with normal tissues.

Preliminary study of plasma vascular endothelial growth factor (VEGF) during low- and high-dose radiation therapy of dogs with spontaneous tumors

High plasma vascular endothelial growth factor (VEGF) concentrations are associated with radiation resistance and poor prognosis. After an exposure to ionizing radiation in cell culture an early phase and a late phase of increased VEGF have been documented. The activation was dependent on the radiation dose. Therefore, the purpose of this study was to measure baseline plasma VEGF and changes in VEGF over the course of fractionated radiation therapy in dogs with spontaneous tumors. Dogs with tumors had a significantly higher pretreatment plasma VEGF than did dogs without tumors. Immediately after irradiation no increased plasma VEGF was observed. Over the course of radiation therapy there was an increased plasma VEGF in dogs treated with low doses per fraction/high total dose, whereas plasma VEGF remained stable in dogs irradiated with high doses per fraction/low total dose. The regulatory mechanisms are very complex, and therefore the value of plasma VEGF measurements as an indirect marker of angiogenesis induced by radiotherapy is limited.

Canine malignant hemangiosarcoma as a model of primitive angiogenic endothelium

Hemangiosarcoma (HSA) is a common untreatable cancer of dogs that resembles human angiosarcoma. Detailed studies of these diseases have been historically hindered by the paucity of suitable reagents. Here, we show that expression of CD117 (c-Kit) can distinguish primitive (malignant) from mature (benign) proliferative endothelial lesions, and we describe eight independent cell lines derived from canine HSA explants. Endothelial origin was confirmed by sustained expression of surface CD105 (endoglin), CD146 (MUC18), and CD51/CD61 (alpha(v)beta(3) integrin). The cell lines showed anchorage-independent growth and were motile and invasive when cultured on a basement membrane matrix. They required endothelial growth factors for growth and survival, and they could be induced to form tubular structures resembling blood vessels when cultured under low calcium conditions. The formation of vessel-like structures was blocked by nicotine, and restored by FK506, suggesting that 'nuclear factor of activated T cells' activity prevents differentiation of these cells. In summary, these cell lines represent a unique and novel resource to improve our understanding of endothelial cell biology in general and canine HSA in particular.

Hemangiosarcoma in dogs and cats

Hemangiosarcoma (HSA, including angiosarcoma and malignant hemangioendothelioma) is a highly malignant tumor derived from the endothelial cell line and is characterized by early and aggressive metastasis. HAS is a common tumor type in dogs, but is rare in other species. Treatment options include surgery, chemotherapy, and possibly radiation, but survival times are invariably short (usually < 1 year), except for patients with superficial dermal HSAs. Further options to treat this tumor type are currently being investigated.