Microvessel count and cerebrospinal fluid basic fibroblast growth factor in children with brain tumours

Hypoxia-inducible factor 1α/vascular endothelial growth factor axis in astrocytomas. Associations with microvessel morphometry, proliferation and prognosis

Hypoxia-inducible factor (HIF)-1alpha is a transcription factor that promotes ischaemia-driven angiogenesis. The aim of this study was to determine the relation of HIF-1alpha to vascular endothelial growth factor (VEGF; an important angiogenic molecule in brain tumours), p53 expression, angiogenesis, proliferative potential and clinical outcome in a large series of diffuse astrocytomas. Expression of HIF-1alpha, VEGF, Ki-67 (a proliferation-associated marker) and p53 was determined immunohistochemically in 83 adult patients with supratentorial diffuse astrocytomas. Microvessels, highlighted by means of anti-CD34 immunohistochemistry, were enumerated with computer-assisted image analysis. Although HIF-1alpha and VEGF were expressed in the majority of cases, their levels increased significantly with increasing grade and proliferative potential. HIF-1alpha positively correlated with microvessel counts and VEGF with total vascular area and the presence of rounder vessel sections. There was a positive correlation of VEGF with p53 expression in astrocytomas and anaplastic astrocytomas. In univariate analysis, both VEGF and HIF-1alpha were associated with shortened survival in the entire cohort, but lost significance when grades II/III and grade IV were analysed separately. Multivariate analysis revealed that the combination of HIF-1alpha with grade was a significant prognostic indicator. HIF-1alpha expression may be used to refine the prognostic information provided by grade in patients with diffuse astrocytomas. Its adverse prognostic effect is most likely mediated by hypoxia, the driving force for HIF-1alpha accumulation.

Histologic measures of angiogenesis in human primary brain tumors

Quantitative determination of the degree of vascularity has been shown to be independently prognostically significant in many human tumor types. In particular, tumor vascularity has known importance in astrocytomas, in which endothelial proliferation is a criterion for anaplasia in many grading schemes. This chapter summarizes the known associations of quantitated microvessel parameters obtained from histologic sections of human brain tumors with clinical outcome, or other pathobiologic factors that have been examined. Among the conclusions are 1) brain tumors have the unique feature of complex "glomeruloid" vessels, as well as heterogeneity of microvascular distribution and caliber; 2) lower-grade astrocytomas incorporate pre-existing vessels, while glioblastomas develop new vessels; 3) quantitation may have additional independent prognostic value over and above routine histologic grade in low-grade astrocytomas with low tumor cell proliferative indices. These findings have implications for the appropriateness of antiangiogenic therapies

Antiangiogenesis: the fifth cancer treatment modality?

PURPOSE/OBJECTIVES

To describe the biologic process of angiogenesis and the potential role of antiangiogenesis therapy in cancer treatment.

DATA SOURCES

Published articles, conference proceedings, and computerized databases.

DATA SYNTHESIS

Angiogenesis is the development of blood vessels. Antiangiogenic agents prevent the development of blood vessels, therefore preventing one mode of cancer metastasis. Clinical trials must be conducted to ascertain the most powerful antiangiogenic therapies. Trials combine chemotherapy, biotherapy, and radiotherapy with antiangiogenic therapy.

CONCLUSIONS

Information from animal studies has revealed that antiangiogenesis is a viable option in treating cancer and preventing metastasis. Although human studies are rare, preliminary results are promising, especially when antiangiogenesis is used in combination with current cancer treatment modalities.

IMPLICATIONS FOR NURSING

Nurses are in a unique position to teach patients about new treatments for cancer. Nurses must be knowledgeable about angiogenesis and the availability of potential antiangiogenesis agents. Nurses will be vital in collecting data in clinical trials, considering the subjective data that will be obtained.

Angiogenic switch during 5T2MM murine myeloma tumorigenesis: role of CD45 heterogeneity

The active role of angiogenesis during disease progression is well recognized in solid tumors. In hematologic malignancies such as multiple myeloma (MM), it is not known whether tumor neovascularization is an epiphenomenon or whether it is actively involved in disease progression. At clinical presentation, myeloma disease and the associated angiogenesis are both well established. Here the 5T2MM murine model was used to analyze angiogenesis during preclinical myeloma stages. Bone marrow (BM) of 5T2MM-inoculated mice was analyzed at weekly intervals until the end stage of the disease. Histologic analysis and assessment of microvessel density (MVD) by CD31 staining demonstrated a preangiogenic stage of small tumor aggregates followed by an angiogenic switch and subsequently an angiogenic stage of progressive tumor growth and large, confluent tumor nodules. Flow cytometric analysis that indicated an increase in percentage CD45- MM cells preceded the angiogenic switch. Real-time polymerase chain reaction (RT-PCR) of sorted CD45+ and CD45- MM cells indicated higher vascular endothelial growth factor 120 (VEGF120) and VEGF164 transcripts in CD45- MM cells. VEGF enzyme-linked immunosorbent assay (ELISA) revealed high secretion by CD45- MM cells but no protein secretion by CD45+ MM cells, indicating angiogenic heterogeneity among the MM cells. These data suggest that, like in solid tumors, angiogenic switch and angiogenic heterogeneity exist in MM.

Serum vascular endothelial growth factor as a tumour marker in soft tissue sarcoma

Background

Vascular endothelial growth factor (VEGF) is a potent tumour-produced angiogenic factor. In this study serum levels of VEGF were measured before treatment and during follow-up in patients undergoing primary treatment for suspected soft tissue sarcoma (STS) to assess the value of serum VEGF as a tumour marker.

Methods

Between April 2001 and September 2002, serum VEGF levels were analysed prospectively in 144 patients undergoing primary treatment (surgery, 123; cytotoxic chemotherapy, ten; oral imatinib, eight; radiotherapy, three) for suspected soft tissue sarcoma. Serum VEGF was measured by immunoassay before treatment, in the immediate postoperative interval in patients undergoing surgery, and during follow-up. Serum VEGF concentrations were also measured in 15 healthy volunteers.

Results

Median pretreatment serum VEGF levels were significantly raised in patients with grade 2 and grade 3 sarcomas compared with concentrations in patients with benign lesions (413 and 467 versus 233 pg/ml respectively; P = 0·007 and P = 0·003 respectively). In patients with tumours that had a high level of VEGF expression before treatment, follow-up measurements reflected disease status after treatment.

Conclusion

Serum VEGF expression correlated with grade in soft tissue sarcoma and reflected response to treatment.

Effect of allogeneic stem cell transplantation on bone marrow angiogenesis in chronic myelogenous leukemia

Increased bone marrow angiogenesis is a poor prognostic marker in patients with chronic myelogenous leukemia (CML). Allogeneic stem cell transplantation (ASCT) can be curative for patients with CML. Studies in myeloma have shown persistent increased bone marrow microvessel density (MVD) after autologous transplantation. It is not clear if abnormal bone marrow angiogenesis persists following a curative intervention like allogeneic transplantation. We evaluated MVD from bone marrow samples obtained just prior to and at 3-5 months after ASCT in 24 patients with CML. The median MVD pre-transplant was 14 (4-37), with 11 patients having high-grade angiogenesis and 13 having low grade. The median post transplant MVD was 20 (range 5-36), with 12 patients having high-grade angiogenesis and 12 low grade. The median time between biopsies was 4 months (range 1-6 months). The microvessels in the post transplant bone marrow appeared morphologically different with striking dilatation and sinusoidal appearance compared to the pre-transplant marrow. However, there was no significant change in MVD following transplant (P=0.8, paired t-test). Abnormal bone marrow angiogenesis appears to persist in the bone marrow following ASCT for CML, at least in the short term.

Angiogenic factors in the central nervous system

The past decade has seen considerable advances in the understanding of angiogenesis. Blood vessel development and growth in the central nervous system are tightly controlled processes that are regulated by angiogenic factors. Angiogenic factors have been implicated in the pathogenesis of a wide variety of disorders, including primary and metastatic brain tumors, aneurysms, arteriovenous malformations, and cavernous malformations. The potential clinical applications of angiogenesis research include inhibition of angiogenesis to control brain tumors and therapeutic angiogenesis to promote collateral blood vessel formation among patients at risk of ischemia. This article summarizes the processes of blood vessel formation in the brain, examines the angiogenic factors that are prominent in the central nervous system, reviews the clinical use of angiogenesis inhibitors, and identifies areas for future investigation.

Automated tracing and change analysis of angiogenic vasculature from in vivo multiphoton confocal image time series

Automated methods are described for tracing and analysis of changes in angiogenic vasculature imaged by a multiphoton laser-scanning confocal microscope. Utilizing chronic animal window models, time series of in vivo 3-D images were acquired on approximately the same target volume of the same specimen while undergoing angiogenic change (typically every 24 h for 7 days). Objective, precise, 3-D, rapid, and fully automated vessel morphometry was performed using an adaptive tracing algorithm that is based on a generalized irregular cylinder model of the vasculature. This algorithm was found to be not only adaptive enough for tracing angiogenic vasculature, but also very efficient in its use of computer memory, and fast, taking less than 1 min to trace a 768 x 512 x 32, 8-bit/pixel 3-D image stack on a Dell Pentium III 1-GHz computer. The automatically traced centerlines were manually validated on six image stacks and the average spatial error was measured to be 2 pixels, with an average concordance of 81% between manual and automated traces on a voxel basis. The tracing output includes geometrical statistics of traced vasculature and serves as the basis of statistical change analysis. The computer methods described here are designed to be scalable to much larger hypothesis testing studies involving quantitative measurements of tumor angiogenesis, gene expression relative to known vascular structures, and impact of drug delivery.

Distinct role of fibroblast growth factor-2 and vascular endothelial growth factor on tumor growth and angiogenesis

Tumors express more than a single angiogenic growth factor. To investigate the relative impact of fibroblast growth factor-2 (FGF-2) and vascular endothelial growth factor (VEGF) on tumor growth and neovascularization, we generated tumor cell transfectants differing for VEGF and/or FGF-2 expression. Human endometrial adenocarcinoma HEC-1-B-derived Tet-FGF-2 cells that express FGF-2 under the control of the tetracycline-responsive promoter (Tet-off system) were further transfected with a VEGF(121) anti-sense (AS-VEGF) cDNA. Next, Tet-FGF-2 and AS-VEGF/Tet-FGF-2 cells were transplanted subcutaneously in nude mice that received tetracycline or not in the drinking water. Simultaneous expression of FGF-2 and VEGF in Tet-FGF-2 cells resulted in fast-growing lesions characterized by high blood vessel density, patency and permeability, and limited necrosis. Blood vessels were highly heterogeneous in size and frequently associated with pericytes. Inhibition of FGF-2 production by tetracycline caused a significant decrease in tumor burden paralleled by a decrease in blood vessel density and size. AS-VEGF expression resulted in a similar reduction in blood vessel density associated with a significant decrease in pericyte organization, vascular patency, and permeability. The consequent decrease in tumor burden was paralleled by increased tumor hypoxia and necrosis. A limited additional inhibitory effect was exerted by simultaneous down-regulation of FGF-2 and VEGF expression. These findings demonstrate that FGF-2 and VEGF stimulate vascularization synergistically but with distinctive effects on vessel functionality and tumor survival. Blockade of either one of the two growth factors results in a decrease in blood vessel density and, consequently, in tumor burden. However, inhibition of the expression of VEGF, but not of FGF-2, affects also vessel maturation and functionality, leading to tumor hypoxia and necrosis. Our experimental model represents an unique tool to investigate anti-neoplastic therapies in different angiogenic environments.

Intracavitary VEGF, bFGF, IL-8, IL-12 levels in primary and recurrent malignant glioma

Intracavitary levels of VEGF, bFGF, IL-8 and IL- 12 were evaluated by ELISA in 45 patients, 7 with recurrent anaplastic astrocytoma (rAA), 12 with glioblastoma (GBM) and 26 with recurrent glioblastoma (rGBM). In 25 patients plasma levels of the molecules were also quantitated. Twenty-three healthy controls were also studied for plasma concentrations of the same molecules. Plasma levels of VEGF (mean 33.89 +/- 6.71 pg/ml) and bFGF (mean 11.1 +/- 3.24 pg/ml) were higher in patients than in controls (mean 16.78 +/- 3.7 pg/ml for VEGF, mean 0.21 +/- 0.09 pg/ml for bFGF) (p = 0.04 and p = 0.001, respectively) while plasma IL-12 levels were lower (mean 45.6 +/- 1.5 pg/ml in patients, mean 79.7 +/- 1.3 pg/ml in controls) (p = 0.009). Intracavitary VEGF levels were 5-53.307 fold higher (mean 90,900 +/- 24,789 pg/ml) than in the corresponding plasma. Also IL-8 concentrations were higher in intracavitary fluid (mean 6,349.76 +/- 1,460.93 pg/ml) than in plasma (mean 43.44 +/- 24.82 pg/ml). Maximum VEGF levels were found in tumor fluid of recurrent glioblastoma patients (mean 147,678 +/- 39.903 pg/ml), intermediate levels in glioblastoma patients (mean 20,322 +/- 11,892 pg/ml) and lower levels in rAA patients (mean 9,111 +/- 5,789 pg/ml). The data also suggest that higher intracavitary levels of VEGF and IL-8, and lower IL-12 levels, may be correlated with shorter adjunctive survival times, but more data will need to be collected to establish this correlation clearly.

NAB2, a corepressor of EGR-1, inhibits vascular endothelial growth factor-mediated gene induction and angiogenic responses of endothelial cells

In this study we have investigated the role of a specific corepressor of EGR-1, NAB2, to down-regulate vascular endothelial growth factor (VEGF)-induced gene expression in endothelial cells and to inhibit angiogenesis. Firstly, we show a reciprocal regulation of EGR-1 and NAB2 following VEGF treatment. During the initial phase EGR-1 is rapidly induced and NAB2 levels are down-regulated. This is followed by a reduction of EGR-1 and a concomitant increase of NAB2. Secondly, using the tissue factor gene as a readout for VEGF-induced and EGR-1-regulated gene expression we demonstrate that NAB2 can completely block VEGF-induced tissue factor reporter gene activity. Thirdly, by adenovirus-mediated expression we show that NAB2 inhibits up-regulation of tissue factor, VEGF receptor-1, and urokinase plasminogen activator mRNAs even when a combination of VEGF and bFGF is used for induction. In addition, NAB2 overexpression significantly reduced tubule and sprout formation in two different in vitro angiogenesis assays and largely prevented the invasion of cells and formation of vessel-like structures in the murine Matrigel model. These data suggest that NAB2 regulation represents a mechanism to guarantee transient EGR-1 activity following exposure of endothelial cells to VEGF and that NAB2 overexpression could be used to inhibit signals involved in the early phase of angiogenesis.

Therapies directed at vascular endothelial growth factor

The inhibition of angiogenesis through vascular endothelial growth factor (VEGF) receptor targeting is a strategy that is relatively tumour selective. The high selectivity achieved with neutralising antibodies, soluble receptors and ribozymes reduces the risk of adverse reactions not related to VEGF inhibition itself. Small-molecule, orally-active protein kinase inhibitors provide an attractive alternative for chronic therapy, although specifically targeting a small subset of protein kinases from the approximately 550 expressed in mammalian cells is a challenge. Current efforts have resulted in promising clinical data for several synthetic VEGF receptor kinase inhibitors, of which PTK787/ZK222584 and ZD6474 are proceeding into large size clinical trials. It seems likely that blockers of the VEGF signalling pathway will be unsuitable for monotherapy, and that their role will be as an adjunct to additional antiangiogenic agents together with directly-acting antitumour agents or radiation therapy. Caution is needed with combinations of anti-VEGF therapies and cytotoxic agents, as coadministration of cytotoxic agents with either the kinase inhibitor SU5416 or the VEGF antibody avastin appears to be associated with bleeding and thrombotic adverse events.

Bone marrow angiogenesis in multiple myeloma: effect of therapy

Recent studies have demonstrated that angiogenesis has a role in haematological malignancies, including multiple myeloma. Multiple myeloma is characterized by inevitable relapse after standard or high-dose chemotherapy. To study the effect of chemotherapy on bone marrow angiogenesis in patients with multiple myeloma, we used two methods to evaluate bone marrow angiogenesis in patients with newly diagnosed multiple myeloma, comparing these findings with those from bone marrow obtained after standard chemotherapy. Before therapy, an increased degree of bone marrow angiogenesis and a high bone marrow plasma cell labelling index (PCLI) were predictive of poorer survival. As estimated by microvessel density (MVD), the median survivals for patients with low-grade, intermediate-grade and high-grade angiogenesis were 77, 30 and 14 months respectively. After therapy, the MVD did not change significantly. However, when patients with at least a partial response were considered separately, they showed a decrease in MVD. Post-therapy PCLI was predictive of survival, but post-therapy MVD was not. There was good correlation between angiogenesis estimated by visual grading and that determined by MVD assessment. We conclude that the degree of bone marrow angiogenesis is a prognostic marker in patients with multiple myeloma and does not decrease significantly after therapy.

Anti-angiogenic agents for the treatment of brain tumors

It is accepted that novel therapeutic approaches are needed for the majority of patients with malignant brain tumors. The vascularity of many primary brain tumors and the encouraging preclinical studies suggest that antiangiogenic agents have the potential to become an important component of multimodality treatment of patients with brain tumors. The understanding of the biology of angiogenesis is improving rapidly, offering the hope for more specific vascular targeting of brain tumor neovasculature. Neuroimaging techniques evaluating the angiogenic process and the impact of antiangiogenic agents will be an important tool for the rapid development of these novel therapeutic agents.

An invasion-independent pathway of blood-borne metastasis: a new murine mammary tumor model

It is generally believed that active invasion by cancer cells is essential to the metastatic process. In this report, we describe a murine mammary tumor (MCH66) model of metastasis that does not require invasion into the vascular wall of both the primary tumor and the target organ, in this case, the lung. The process involves intravasation of tumor nests surrounded by sinusoidal blood vessels, followed by intravascular tumor growth in the lung, without penetration of the vascular wall during the process. Comparative studies using a nonmetastatic MCH66 clone (MCH66C8) and another highly invasive metastatic cell line (MCH416) suggested that high angiogenic activity and sinusoidal remodeling of tumor blood vessels were prerequisites for MCH66 metastasis. Differential cDNA analysis identified several genes that were overexpressed by MCH66, including genes for the angiogenesis factor pleiotrophin, and extracellular matrix-associated molecules that may modulate the microenvironment toward neovascularization. Our analyses suggest that tumor angiogenesis plays a role in the induction of invasion-independent metastasis. This model should prove useful in screening and development of new therapeutic agents for cancer metastasis.

Intra-tumoural microvessel density in human solid tumours

Over the last decade assessment of angiogenesis has emerged as a potentially useful biological prognostic and predictive factor in human solid tumours. With the development of highly specific endothelial markers that can be assessed in histological archival specimens, several quantitative studies have been performed in various solid tumours. The majority of published studies have shown a positive correlation between intra-tumoural microvessel density, a measure of tumour angiogenesis, and prognosis in solid tumours. A minority of studies have not demonstrated an association and this may be attributed to significant differences in the methodologies employed for sample selection, immunostaining techniques, vessel counting and statistical analysis, although a number of biological differences may account for the discrepancy. In this review we evaluate the quantification of angiogenesis by immunohistochemistry, the relationship between tumour vascularity and metastasis, and the clinicopathological studies correlating intra-tumoral microvessel density with prognosis and response to anti-cancer therapy. In view of the extensive nature of this retrospective body of data, comparative studies are needed to identify the optimum technique and endothelial antigens (activated or pan-endothelial antigens) but subsequently prospective studies that allocate treatment on the basis of microvessel density are required.

Inhibition of angiogenesis: treatment options for patients with metastatic prostate cancer

Prostate cancer is the most frequently diagnosed malignancy and the second most common cause of cancer-related death in men in the United States. Unfortunately, at the current time, no curative treatments are available for metastatic prostate cancer. As is the case for most solid tumors, the recruitment of blood vessels (angiogenesis) is key for the progression and metastasis of prostate cancer. Inhibition of this process is an attractive approach to treatment. Many antiangiogenic agents are currently in clinical development. The following discussion will outline the importance of angiogenesis in the metastasis and progression of prostate cancer, summarize the current surrogate markers of angiogenesis available for the drug development of antiangiogenic agents, and review examples of investigational agents that target tumor angiogenesis (e.g., TNP-470, Thalidomide, CC5013, Carboxyamido-triazole (CAI), Endostatin. SU5416, SU6668, Bevacizumab (Anti-VEGFrhuMAb), and 2-Methoxyestradiol).

In vivo quantitation of tumour vascularisation assessed by Doppler sonography in rat mammary tumours

This study was designed to evaluate high-frequency power Doppler (PDS) and to quantify treatment-induced changes in an experimental autochthonous mammary tumour model in rats. A total of 13 rats with N-methyl, N-nitroso urea-induced mammary tumours were split into three courses; 6 rats were treated with epirubicin, 3 received a placebo injection and 4 had irradiation of their tumour with a direct electron beam using a single dose of 18 Gy. In all groups, treatment began when the tumour area reached at least 1 cm(2) and was preceded by the first power Doppler sonography study of the tumour (Echo #1). Echo #2 was carried out in the middle of the placebo or epirubicin treatment (after 3 weeks) or 7 days after irradiation in the irradiated group. Echo #3 was carried out at the end of placebo or epirubicin treatment or 28 days after irradiation. Then colour pixel density (CPD) and vascularity index (VI) were quantitated. Intraobserver and interobserver variability of the CPD and VI quantitation was low (r = 0.99 and 0.97, respectively, for intraobserver and interobserver variability of the CPD values). The monitoring of CPD and VI showed an increase with time during the observation period. No increase in CPD or VI was observed in treated mammary tumours (p < 0.01). Power Doppler sonography quantitation of angiogenesis is reproducible, noninvasive and feasible in this in vivo breast cancer model. The monitoring of angiogenesis according to different treatments is feasible in real-time. Further studies are needed to investigate the predictive value of CPD and VI on sensitivity of mammary tumours to anticancer treatment.

Aberrant p53 expression correlates with expression of vascular endothelial growth factor mRNA and interleukin-8 mRNA and neoangiogenesis in non-small-cell lung cancer

PURPOSE

To evaluate interactions between expressions of tumor suppressor gene p53 and angiogenic factors vascular endothelial cell growth factor (VEGF) and interleukin-8 (IL-8) and their effect on tumor angiogenesis and patient prognosis in non--small-cell lung cancer (NSCLC).

PATIENTS AND METHODS

p53, VEGF, IL-8, and the microvessel endothelium were immunostained, and VEGF and IL-8 mRNA expression were quantified using the real-time quantitative reverse-transcription polymerase chain reaction in 65 NSCLC surgical specimens. Aberrant p53 expression was correlated with VEGF and IL-8 mRNA expression, microvessel count (MVC), other clinical-pathologic variables, and patients' survival.

RESULTS

Tumors with high aberrant p53 expression showed significantly higher VEGF and IL-8 mRNA expression and MVC than those with low aberrant p53 expression (P <.001). When tested as a continuous variable, aberrant p53 expression correlated strongly and positively with VEGF and IL-8 mRNA expression and MVC (P <.0001). Tumors with high aberrant p53 expression were associated with mediastinal or distant lymph node metastasis (P =.006). Survival and postoperative relapse time were significantly shorter in patients with high aberrant p53 expression tumors than in those with low aberrant expression tumors (P <.0001). A significant difference in survival was also seen between patients with high and low tumoral VEGF mRNA expression and between those with high and low tumoral IL-8 mRNA expression (P <.0001).

CONCLUSION

We report here for the first time that aberrant p53 expression is strongly positively correlated with VEGF mRNA and IL-8 mRNA expression in NSCLC. This result indicates that aberrant p53 expression may play a significant role in regulation of VEGF and IL-8 expression and be involved in controlling angiogenesis and explains the adverse prognosis of cancers with high aberrant p53 expression.

New Directions in the Treatment of Cancer: Inhibition of Signal Transduction

In recent years, it has become increasingly apparent that proteins regulated by activated oncogenes or mutated tumor suppressor genes are responsible for the transformation of normal cells to malignant cells as well as for malignant characteristics such as uncontrolled cellular proliferation and the development of metastases. These proteins may be soluble factors, receptors on cell surfaces, or intracellular enzymes that produce signals that stimulate cellular development or proliferation. This process is called signal transduction .In many cases, increased amounts of these proteins have been demonstrated in cancer cells (over normal cells) and have been found to carry prognostic significance. New approaches in cancer treatment are being designed to block such proteins; this approach is termed signal transduction inhibition. !Specific protein targets that anticancer therapies have been developed to inhibit include epidermal growth factor receptors, tyrosine kinase, farnesyl transferase, and various promoters of angiogenesis.

Clinical significance of urinary vascular endothelial growth factor and microvessel density in patients with renal cell carcinoma

OBJECTIVES

To investigate the urinary vascular endothelial growth factor (VEGF) levels from patients with renal cell carcinoma (RCC). Neovascularization, an essential event for the growth of solid tumors, is regulated by a number of angiogenic factors. VEGF is thought to exert potent angiogenic activity.

METHODS

Urine samples were obtained before radical nephrectomy from 27 patients with RCC and 10 control subjects with no evidence of cancer or inflammatory disease. VEGF was measured by enzyme-linked immunosorbent assay in the urine and corrected according to the 24-hour urine concentration of creatinine. The microvessel density was measured by immunohistochemical staining with CD31 monoclonal antibody. Nuclear morphometry was performed by photomicroscopy.

RESULTS

The corrected urinary VEGF levels in patients with RCC were much higher than those in the normal control group (P = 0.039) and were more elevated in patients with higher stages of RCC (Stages III and IV versus Stages I and II; P = 0.024). A tendency was also noted for the VEGF levels to be higher according to cell grade. However, no statistical correlation was found between the corrected urinary VEGF and age, sex, tumor size, cell type, microvessel density, platelet count, or hemoglobin. The nuclear area was higher with more advanced-stage tumors (P = 0.043) and tended to increase according to the tumor cell grade.

CONCLUSIONS

The results of this study indicate that urinary VEGF levels are increased in patients with RCC. However, they may not reflect the underlying angiogenic activity, and it may be that other angiogenic factors play a more prominent role.

Thalidomide as an anti-angiogenic agent in relapsed gliomas

BACKGROUND

Thalidomide (alpha-phthalimidoglutarimide), a synthetic sedative drug, has anti-angiogenic properties due to inhibition of growth-factor mediated neovascularisation and has been shown to inhibit tumour growth in experimental solid tumour models.

AIM

To assess response of recurrent malignant gliomas to thalidomide.

METHODS

Eighteen patients with recurrent gliomas were enrolled to an open, non-randomised phase II trial between October 1997 and December 1999. All patients had failed following treatment with radiotherapy and chemotherapy with PCV and/or temozolomide regimens. Eleven patients had high-grade gliomas de novo and 7 high-grade gliomas following transformation of low-grade gliomas. Thalidomide was prescribed at 100 mg/day p.o. continuously. Response was assessed at 4-weekly intervals. Disease progression was defined as neurological deterioration and/or radiological evidence of increased tumour size. Treatment was discontinued at the time of disease progression, or if toxicity occurred, or at patients' request.

RESULTS

Thalidomide was prescribed for a median of 42 days (range 7-244). Treatment was discontinued due to toxicity (peripheral sensory neuropathy) in 1 patient. Six patients died before response could be fully assessed and are classified as non-responders. Of 12 who continued treatment for more than 4 weeks, 1 patient had clinical and radiological response (PR), 2 patients had stable disease for 2 and 4 months respectively and 9 patients had disease progression. The median survival from the start of thalidomide was 2.5 months.

CONCLUSION

The efficacy of thalidomide in terms of response in recurrent gliomas is low, with a partial response rate of only 6%. Future studies should investigate thalidomide in combination with other agents and at an earlier stage of disease. Methods to assess anti-angiogenic properties such as changes in tumour vasculature could be employed as initial surrogate end-points in the investigation of efficacy.

Clinical importance of serum vascular endothelial and basic fibroblast growth factors in children with acute lymphoblastic leukemia

The aim of this study is to evaluate, for the first time serum levels of vascular endothelial growth factor (s-VEGF), and basic fibroblast growth factor (s-b FGF) in children with acute lymphoblastic leukemia (ALL), and its relation to clinical manifestations of the disease. Although VEGF and b FGF have been suggested to be reliable prognostic indicators and important tools for treatment approach in malignant haematopoietic and solid tumours, experience in childhood ALL has been limited to only one study on angiogenesis and urine b FGF. All 31 ALL patients included in the present study at the time of diagnosis and in remission, and all 10 control children had detectable serum levels of VEGF and b FGF. The median level of s-VEGF at the time of diagnosis was significantly lower than in the control group and at the time of remission (respectively p = 0.005, p = 0.0001). Twenty six of 31 patients had an increasing trend of s-VEGF levels in remission reaching control values compared with the levels obtained at diagnosis. S-b FGF median levels at the time of diagnosis were the same as those of the control group, significantly lower than the median s-b FGF values in remission (p = 0.001). In patients with lower platelet counts (< 50 x 10(9)/L) growth factors (VEGF and b FGF) were lower than in patients with higher platelet counts (p = 0.0009 and p = 0.002 respectively). In patients with hepatosplenomegaly (longitudinal size > 3 cm) b FGF levels were higher than patients without hepatosplenomegaly (P = 0.003). We concluded that the increment in both s-VEGF and s-b FGF in patients in remission may be related to the renewal of normal haematopoiesis. The increase in s-VEGF values in 26 out of 31 patients in remission compared to normal control values, may also suggest that there is clinical significance in ALL patients.

Examining new models for the study of autocrine and paracrine mechanisms of angiogenesis through FGF2-transfected endothelial and tumour cells

Angiogenesis is the process of generating new capillary blood vessels. Uncontrolled endothelial cell proliferation is observed in tumour neovascularization. Several growth factors and cytokines have been shown to stimulate endothelial cell proliferation in vitro and in vivo and among them FGF2 was one of the first to be characterised. FGF2 is a Mr 18,000 heparin-binding cationic polypeptide that induces proliferation, migration, and protease production in endothelial cells in culture and neovascularization in vivo. FGF2 interacts with endothelial cells through two distinct classes of receptors, the high affinity tyrosine-kinase receptors (FGFRs) and low affinity heparan sulfate proteoglycans (HSPGs) present on the cell surface and in the extracellular matrix. Besides experimental evidence for paracrine mode of action for FGF2, some observations raise the hypothesis that FGF2 may also play an autocrine role in endothelial cells. FGF2 may therefore represent a target for anti-angiogenic therapies. In order to assess the angiostatic potential of different classes of compounds, novel experimental models have been developed based on the autocrine and/or the paracrine capacity of FGF2.

Preferential susceptibility of brain tumors to the antiangiogenic effects of an alpha(v) integrin antagonist

OBJECTIVE

Brain tumors are highly angiogenic, and their growth and spread depend on the generation of new blood vessels. We examined the effect of the cyclic peptide antagonist pentapeptide EMD 121974, an antiangiogenic agent, on orthotopic and heterotopic brain tumor growth.

METHODS

The human brain tumor cell lines DAOY (medulloblastoma) and U87 MG (glioblastoma) were injected into either the forebrain (orthotopic) or the subcutis (heterotopic) of nude mice, and daily systemic treatment with the active peptide was initiated after tumors were established.

RESULTS

All control animals with orthotopic brain tumors and that received the inactive peptide EMD 135981 daily died as a result of tumor progression within 4 to 6 weeks; tumors measured 3 to 5 mm in diameter. In contrast, mice with orthotopic tumors that were treated daily with the active peptide survived for more than 16 weeks, and histological examination of the brains after 4, 8, and 12 weeks showed either no tumors or microscopic residual tumors. The growth of these brain tumor cells injected simultaneously or separately into the subcutis of nude mice (heterotopic model) was not affected by the active peptide, suggesting that the brain environment is a critical determinant of brain tumor susceptibility to growth inhibition by this pentapeptide.

CONCLUSION

The cyclic pentapeptide EMD 121974 may become a treatment option specific to brain tumors. Because of its antiangiogenic effect, its use may be especially indicated after tumors are removed surgically.

Angiogenesis and p53 protein expression in breast cancer: prognostic roles and interrelationships

The authors have analyzed, on the one hand, the prognostic impact of microvessel density (MVD) and p53 protein expression in patients with breast cancer, and on the other hand, the correlation between the microvascular pattern and the p53 protein expression. Tumors from 120 patients whose paraffin-embedded tissue blocks were available were analyzed using the immunohistochemical method. MVD and p53 protein expression were correlated with histologic grade and tumor size, respectively. The patients with highly vascularized tumor (high MVD) had decreased overall survival (p = 0.04), whereas overexpressed p53 patients did not. In multivariate analysis, axillary lymph node status (p = 0.007), tumor size (p = 0.01), and MVD (p = 0.02) showed important prognostic influence on overall survival. When the simultaneous influence of MVD and p53 protein expression on survival were analyzed, no interrelationship was detected. The results demonstrate the prognostic impact of MVD on overall survival in breast cancer and no association between MVD and p53 protein expression.

Genes that regulate metastasis and angiogenesis

Genetic instability and an accumulation of genetic and epigenetic changes during tumor progression lead to an increasingly aggressive and treatment-resistant phenotype, and ultimately metastasis. In recent years it has become well established that angiogenesis, the process by which new vasculature is formed from pre-existing vessels, is an essential component to primary tumor growth and distant metastasis. A greater understanding of the complex multitude of factors involved in tumor angiogenesis and metastasis is fundamental to the development of potential therapeutics to treat malignant disease. As highlighted throughout this review, angiogenesis and metastasis share many common cellular and molecular features. We will briefly discuss the pertinent genes involved in the regulation of angiogenesis and metastasis.

Descriptive analysis and quantification of angiogenesis in human brain tumors

Quantitative determination of the degree of vascularity has been shown to be independently prognostically significant in many human tumor types. In particular, tumor vascularity has known importance in astrocytomas, in which endothelial proliferation is a criterion for anaplasia in many grading schemes. This review analyzes reports of microvessel quantification performed on histologic sections of human brain tumors, and in which correlations with clinical outcome, or other pathobiologic factors have been made. Among the conclusions are: (1) brain tumors have the unique feature of complex 'glomeruloid' vessels, as well as heterogeneity of microvascular distribution and caliber; (2) lower-grade astrocytomas may incorporate pre-existing vessels, while glioblastomas may develop new vessels; (3) quantification may have additional independent prognostic value over and above routine histologic grade in low-grade astrocytomas with low tumor cell proliferative indices. These findings have implications for the appropriateness of antiangiogenic therapies.

Local anti-angiogenic brain tumor therapies

The critical role of angiogenesis in the growth of solid tumors, including neoplasms of the central nervous system, has provided the impetus for research leading to the discovery of inhibitors of tumor neovascularization. The therapeutic potential of systemically administered antiangiogenic drugs for brain tumors, however, is limited by a variety of anatomic and physiologic barriers to drug delivery. Implantable controlled-release polymers for local drug administration directly into the tumor parenchyma have therefore been developed to achieve therapeutic concentrations of these drugs within the brain while minimizing systemic toxicity. With use of these polymers, successful antiangiogenic therapy for treatment of experimental intracranial malignancies has been achieved. This has been demonstrated with a variety of otherwise unrelated drugs -- including the angiostatic steroids, tetracycline derivatives, and amiloride -- which modulate collagenase activity, and thus, basement membrane and interstitial matrix metabolism. Controlled-release polymers provide a clinically practicable method of achieving sustained antiangiogenic therapy which can be readily used in combination with other treatment modalities such as cytoreductive surgery, radiation, and cytotoxic chemotherapy.

Growth factors in glioma angiogenesis: FGFs, PDGF, EGF, and TGFs

It has become well accepted that solid tumors must create a vascular system for nutrient delivery and waste removal in order to grow appreciably. This process, angiogenesis, is critical to the progression of gliomas, with vascular changes accompanying the advancement of these tumors. The cascade of events in this process of blood vessel formation involves a complex interplay between tumor cells, endothelial cells, and their surrounding basement membranes in which enzymatic degradation of surrounding ground substance and subsequent endothelial cell migration, proliferation, and tube formation occurs. It is likely that a host of growth factors is responsible for mediating these key events. To date, a role for Vascular Endothelial Growth Factor (VEGF) in glioma angiogenesis has been convincingly demonstrated. This review explores the contribution of other growth factors--Fibroblast Growth Factors (FGFs), Platelet-Derived Growth Factor (PDGF), Epidermal Growth Factor (EGF), and Transforming Growth Factors (TGFs)--to glioma angiogenesis. These growth factors may influence glioma angiogenesis by directly stimulating endothelial cell proliferation, by mediating the expression of key proteases on endothelial cells necessary for angiogenesis, or by regulating the expression of VEGF and of each other.

Angiogenesis in head and neck squamous cell carcinoma

Tumour angiogenesis has recently attracted a great deal of attention as a critical part of oncogenesis and a necessary prerequisite for a malignant phenotype. Research into this process not only offers new insights into tumour biology but is also leading to the development of realistic novel and minimally toxic anti-tumour therapies. Various pro-angiogenic and anti-angiogenic cytokines and pathways have been characterized and their interrelationships are becoming increasingly complex as new findings are made. This article reviews the current understanding of tumour angiogenesis, the basic mechanisms involved and the more important and investigated pathways and proteins involved.

Pediatric medulloblastoma: prognostic value of p53, bcl-2, Mib-1, and microvessel density

The aim of this study was to retrospectively assess the prognostic value of p53 and bcl-2 protein expression, cell proliferation index (Mib-1 index), and tumor microvessel density (factor VIII-related antigen) in pediatric medulloblastoma patients. Tumor specimens of 55 patients (age 2-18 years) with medulloblastoma treated with a curative intent between 1972 and 1991 were studied. Slides of paraffin embedded tissue were stained with monoclonal antibodies (mAb) and examined under high power light microscopy for the presence of immunoreactivity. Microvessel density was scored both in the area of most intense staining ('Angio-max') and in 3 additional randomly selected areas. The sum of these 4 scores was termed 'Angio-total'. 'Angio-max' and 'Angio-total' were evaluated separately by two independent investigators to assess reproducibility. None of the parameters studied, i.e. p53 or bcl-2 expression, Mib-1 index or microvessel density scores were associated with patient survival. Microvessel scores between observers were significantly but weakly correlated, with correlation coefficients (r) < 0.5 for both 'Angio-max' and 'Angio-total'. Leptomeningeal spread at diagnosis was the only independent factor associated with a poor survival (p = 0.003). There was no association of leptomeningeal metastasis with any of the biological markers tested in this study.

Regulation of vascular growth and regression by matrix metalloproteinases in the rat aorta model of angiogenesis

Matrix metalloproteinases (MMPs) have been implicated in the formation of microvessels during angiogenesis, but their role in vascular regression is poorly understood. The rat aorta model of angiogenesis was used to study the function of MMPs at different stages of the angiogenic process. Gelatin zymography and Western analysis demonstrated production of MMP-2 and MMP-9 by aortic outgrowths in serum-free collagen gel culture. MMP-2 was found in both culture medium and collagen gel, whereas MMP-9 was predominantly associated with the gel. MMP expression increased gradually during the angiogenic growth phase and stayed high when vessels regressed and collagen lysed around the aortic rings. The MMP inhibitors, batimastat and marimastat, blocked formation of microvessels when added to the culture medium at the beginning of the experiment. They, however, stabilized the microvessels and prevented vascular regression after the angiogenic growth phase. This effect was observed also under conditions of angiogenic stimulation by basic fibroblast growth factor. MMP inhibitor-mediated stabilization of microvessels was associated with inhibition of collagen lysis and accumulation of collagen fibrils in the subendothelial space. This study demonstrates that MMPs promote microvessel formation during the early stages of angiogenesis, but also contribute to the reabsorption of the neovasculature in the later stages of this process. The time-dependent divergent effects of MMPs on microvessel growth and survival may influence the in vivo activity of MMP inhibitors used to treat angiogenesis-dependent disorders.

Plasma levels of soluble CD105 correlate with metastasis in patients with breast cancer

CD105 (endoglin), a receptor for transforming growth factor (TGF) beta1 and beta3 in vascular endothelial cells, is highly up-regulated in blood vessels of tissues where neovascularisation occurs. It modulates endothelial-mesenchymal signalling and is essential for angiogenesis. Indeed, CD105 knock-out mice die from malvascularisation by 11.5 day p.c. In the present study CD105, TGFbeta1 and CD105/TGFbeta1 complexes were quantified in plasma samples from 77 healthy individuals and 92 patients with early stage breast cancer prior to any treatment. When compared with normal controls, both CD105 and CD105/TGFbeta1 complex levels were significantly elevated in breast cancer patients, whereas TGFbeta1 levels were lower in cancer patients. The most important finding to emerge was that CD105 levels were significantly increased in patients who developed distant metastasis compared with disease-free patients. While there was no significant difference between CD105 levels in controls compared to disease-free patients, it was significantly higher in patients with metastatic disease. Thus patients who had died following local relapse or distant metastases possessed the highest levels of CD105. Neither CD105/TGFbeta1 complex nor TGFbeta1 levels correlated with tumour progression. Our data indicate that CD105 might be a valuable novel angiogenic marker for identifying breast cancer patients who are at high risk of developing metastasis.

Inhibition of tumor growth and metastasis by targeting tumor-associated angiogenesis with antagonists to the receptors of vascular endothelial growth factor

Angiogenesis, the formation of new blood vessels, is essential for both tumor growth and metastasis. Recent advances in our understanding of the molecular mechanisms underlying the angiogenesis process and its regulation have led to the discovery of a variety of pharmaceutical agents with anti-angiogenic activity. The potential application of these angiogenesis inhibitors is currently under intense clinical and pre-clinical investigation. Compelling evidence suggests that vascular endothelial growth factor (VEGF) and its receptors play critical roles in tumor-associated angiogenesis, and that they represent good targets for therapeutic intervention. This has been demonstrated in a variety of animal tumor models in which disabling the function of VEGF and its receptors was shown to inhibit both tumor growth and metastasis. We have produced a panel of antibodies directed against the VEGF receptor 2, KDR/F1k-1. These antibodies potently block VEGF/KDR/F1k-1 interaction, and inhibit VEGF-stimulated activation of the receptor and proliferation of human endothelial cells. Further, the antibodies significantly inhibited tumor-associated angiogenesis in several animal models. Antagonists of VEGF and/or its receptors may offer higher specificity towards tumors with reduced side effects, and may be less likely to elicit drug resistance compared to conventional therapy. Anti-angiogenesis therapy represents a novel strategy for the treatment of cancer and other human disorders where pathological angiogenesis is involved.

The clinical manipulation of angiogenesis: pathology, side-effects, surprises, and opportunities with novel human therapies

The first phase of angiogenesis research has provided knowledge of the basic pathobiology of angiogenesis and its manipulation in models, mouse, and man. The first line of therapeutic substances has been devised and is now in clinical trials. New lessons are being learned from clinical observations. Unexpected side-effects are being noted, particularly affecting the nervous system. Other side-effects may be anticipated from a sound knowledge of clinical pathology and recognition of the commonality of angiogenesis to multiple disease mechanisms, but these may be tolerable or avoidable. Angiogenesis researchers await further feedback and ideas from the clinic to stimulate the next phase of basic and applied research.

Angiogenesis in neuroblastoma: relationship to survival and other prognostic factors in a cohort of neuroblastoma patients

PURPOSE

To study angiogenesis in neuroblastoma, using morphometric and computerized image analysis, and correlate the results with survival and other prognostic factors.

PATIENTS AND METHODS

Sixty-nine patients from the Spanish Cooperative Study for Neuroblastoma were studied. Tumoral angiogenesis was studied using an avidin-biotin immunoperoxidase technique with an anti-CD34 antibody. Vascular parameters (VPs) were analyzed by a computerized system. Statistical analysis was also performed.

RESULTS

Sixty-six samples had adequate tumoral tissue, and their tumoral vessels were counted. Endothelial cells were more prominent in pure neuroblastomas than in maturing and more mature tumors. VPs showed no statistical difference between the groups of patients as defined by the levels of the other prognostic factors in neuroblastoma: age, stage, histopathology, TRK-A, P-glycoprotein expression, or MYCN copy number. In patients who relapsed, tumors did not show statistically significant difference in VPs when compared with tumors from patients who did not relapse. There was also no difference in VPs in tumors from living patients when compared with tumors from deceased patients. Overall survival was 75%, and event-free survival was 55% at 50 months.

CONCLUSION

VPs could be adequately determined by a computerized system in neuroblastoma; however, VPs were not predictive of survival for our patients. In our patients, neither disseminated nor local relapses were influenced by the angiogenic characteristics of the tumors.

Increased serum levels of vascular endothelial growth factor predict risk of progression in early B-cell chronic lymphocytic leukaemia

The present study is the first to evaluate serum levels of vascular endothelial growth factor (VEGF) in B-cell chronic lymphocytic leukaemia (CLL). All 68 B-cell CLL patients and 31 control subjects analysed had detectable serum levels of VEGF, with no statistically significant difference between two proups. An aberrant increase of circulating levels of VEGF was found in only 17.6% of cases. B-cell CLL patients whose serum VEGF levels were higher than the median (i.e. 194.8 pg/ml) or 75th percentile (i.e. 288.5 pg/ml) values were more frequently at an advanced clinical stage. In contrast, no correlation with other clinico-biological features representative of either tumour mass [bone marrow (BM) histology, peripheral blood (PB) lymphocytosis, beta-2 microglobulin (beta-2m), LDH, interleukin-6 (IL-6)] or disease-progression (DP) [lymphocyte doubling time (LDT)] was found. Serum levels of VEGF predicted the risk of DP in early CLL. Among 41 patients in Binet stage A, progression-free survival (PFS) was significantly shorter in those patients whose VEGF serum concentrations were above the median value. Interestingly, characteristics of stage A patients stratified according to the median value of VEGF were similar with respect to many clinico-biological features, thus suggesting a possible independent prognostic role for such a marker. Finally, when added to the Rai subclassification, VEGF serum levels identified two groups with different PFS within stages I-II. We conclude that increased serum levels of VEGF can be considered useful for predicting the risk of DP and add prognostic information to the Rai subclassification of stage A CLL.

The role of the vascular phase in solid tumor growth: a historical review

Angiogenesis is a biological process by which new capillaries are formed from pre-existing vessels. It occurs in both physiological conditions such as embryo development, cyclically in the female genital system and during wound repair, and pathological conditions, such as arthritis, diabetic retinopathy and tumors. In solid tumor growth, a specific critical turning point is the transition from the avascular to the vascular phase. Having developed an intrinsic vascular network, the neoplastic mass is able to grow indefinitely (unlike all the other forms, tumor angiogenesis is not limited in time) both in situ and at distant sites (metastasis) in so far as an intrinsic vascular network enables its cells to enter the vascular bed and colonize other organs. Tumor angiogenesis depends mainly on the release by neoplastic cells of growth factors specific for endothelial cells and able to stimulate growth of the host's blood vessels. This review describes its history as traced by the main contributions to the international medical literature and their contents. The specific new paradigm discussed here has been gaining general approval and considerable confirmation, thanks to its possible applications, as recently highlighted by the introduction of anti-angiogenic substances in adjuvant tumor management.

Inhibitory effect of full-length human endostatin on in vitro angiogenesis

Endostatin, a C-terminal product of collagen XVIII, is a very powerful angiogenesis inhibitor. In vivo experiments in mice indicate that endostatin dramatically reduces tumor mass without causing the onset of any resistance to the treatment. Recently, a 12-aa shorter human endostatin has been purified from plasma, but is ineffective in in vitro angiogenesis assays. Here we report that the full-length human recombinant endostatin has a potent inhibitory activity in in vitro angiogenesis assays. Two powerful angiogenic factors were used to stimulate endothelial cells: FGF-2 and VEGF-165. Endostatin prevented cell growth both in the basal condition and after stimulation with FGF-2 or VEGF-165. Migration of microvascular endothelial cells toward FGF-2 or VEGF-165 was impaired, both when cells were pretreated with the inhibitor and when endostatin was added together with the growth factors. Furthermore, experiments of inhibition of proliferation performed on nonmicroendothelial cells showed that endostatin was ineffective. This study indicates that human endostatin is a potent angiogenesis inhibitor and suggests its use in human anticancer therapy.

Increased serum levels of vascular endothelial growth factor in patients with renal cell carcinoma

Neovascularization, an essential event for the growth of solid tumors, is regulated by a number of angiogenic factors. One such factor, vascular endothelial growth factor (VEGF), is considered to exert a potent angiogenic activity, as indicated by immunohistochemical and molecular evidence. In this study we investigated the serum VEGF level (s-VEGF) in patients with renal cell carcinoma (RCC). s-VEGF in peripheral blood samples was analyzed in 40 RCC patients and 40 patients without cancer (controls) using a sandwich enzyme-linked immunoassay. In 20 RCC patients, serum samples were obtained separately from the bilateral renal veins. s-VEGF was also measured before, 4 and 8 weeks after nephrectomy in 11 patients. There were significant differences in s-VEGF between the RCC patients and the controls (207.3+/-32.9 vs. 71.5+/-9.1 pg/ml, mean+/-SE) (P<0.005), between the tumor-bearing renal veins and the contralateral ones (P<0.01), between the pre- and post-nephrectomy situations (P<0.01) and among the various parameters of tumor status such as tumor extent (P<0.001) and existence of metastasis (P<0.001). s-VEGF significantly correlated with the tumor volume obtained by a three-dimensional measurement (r=0.802, P<0.0001). The sensitivity and specificity of s-VEGF at the cut-off level of 100 pg/ml, as determined by the receiver-operating-characteristics curve, were 80.0% and 72.5%, respectively. The results indicate that tumor tissue of RCC liberates VEGF into the systemic blood flow and that s-VEGF is a possible marker for RCC.

Altered formation and bulk absorption of cerebrospinal fluid in FGF-2-induced hydrocephalus

Upregulation of certain growth factors in the central nervous system can alter brain fluid dynamics. Hydrocephalus was produced in adult Sprague-Dawley rats by infusing recombinant basic fibroblast growth factor (FGF-2) at 1 microg/day into a lateral ventricle for 2, 3, 5, or 10-12 days. Lateral and third ventricular enlargement progressively increased from 2 to 10 days. Ventriculomegaly was also induced by a 75% reduced dose of FGF-2. At 10-12 days, there was a 29% attenuation in cerebrospinal fluid (CSF) formation rate, from 2. 5 to 1.8 microliter/min (P < 0.01). Choroid plexus, the main site of CSF secretion, had an augmented number of dark epithelial cells, which have previously been associated with decreased choroidal fluid formation. The twofold elevated resistance to CSF absorption, i.e., 0.8 to 1.7 mmHg. min(-1). microliter(-1), was attributable, at least in part, to enhanced fibrosis and collagen deposits in the arachnoid villi, a major site for CSF absorption. Normal CSF pressure (2-3 mmHg) was consistent with a patent cerebral aqueduct and reduced CSF formation rate. The FGF-2-induced ventriculomegaly is interpreted as an ex vacuuo hydrocephalus brought about by an altered neuropil and interstitium of the brain.

Endothelial nitric oxide synthase expression in tumor vasculature is correlated with malignancy in human supratentorial astrocytic tumors

OBJECTIVE

Endothelial nitric oxide synthase (eNOS) may play an important role in the regulation of tumor blood flow and vascular permeability. However, there have been no reports describing alterations of eNOS expression in relation to malignant progression in human astrocytic tumors. We immunohistochemically studied the relationship between eNOS expression in tumor vasculature and malignancy in supratentorial astrocytic tumors.

METHODS

Tissue samples were obtained from 12 patients with low-grade astrocytomas, 10 with anaplastic astrocytomas, and 17 with glioblastomas. Normal brain tissue samples were obtained from four patients with other brain diseases. Immunohistochemical staining was performed using the avidin-biotin complex method, with polyclonal anti-eNOS antibody, and the levels of eNOS expression in endothelial cells were evaluated as slight, moderate, or intense on the basis of eNOS immunoreactivity. The proliferative potential was assessed as the MIB-1 staining index for tumor cells.

RESULTS

The expression of eNOS was slight in all specimens of normal brain tissue, slight in 7 and moderate in 5 specimens of low-grade astrocytoma, slight in 2, moderate in 6, and intense in 2 specimens of anaplastic astrocytoma, and moderate in 5 and intense in 12 specimens of glioblastoma. The MIB-1 staining index (mean+/-standard deviation) was 0.2+/-0.2% for normal specimens, 1.8+/-0.6% for low-grade astrocytomas, 9.6+/-6.9% for anaplastic astrocytomas, and 18.5+/-7.7% for glioblastomas. The MIB-1 staining indices for slight, moderate, and intense eNOS expression were 2.0+/-2.3%, 10.8+/-9.8%, and 16.9+/-7.7%, respectively.

CONCLUSION

Expression of eNOS in tumor vessels was significantly correlated with histological grade and proliferative potential. These findings suggest that astrocytic tumor vessels possess higher activity for nitric oxide production than do normal vessels.