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

Prognostic and predictive value of intratumoral microvessels density in operable non-small-cell lung cancer

Experimental evidence suggests that tumor growth and progression depend on angiogenesis. In a retrospective study we evaluated the relationship between tumor angiogenesis and survival in patients with NSCLC treated with potentially curative surgery between 1992 and 1997. The study population consisted of 76 patients. An anti-CD34 monoclonal antibody was used to measure angiogenesis in tumor samples. Angiogenesis was quantified in terms of microvessel count (MVC): in each sample the three most intense regions of neovascularization were identified under low microscopic power. A x250 field in each of the three areas was then counted and the highest count of the three fields was recorded. Disease free (DFS) and overall survival (OS) during follow up were evaluated. Gender, age, stage, histologic type and KI-67 were the other factors considered for analysis. The median MVC in our series was 41.5. Among the clinicopathologic parameters examined the microvessel count was the only one to show a significant association with disease free survival in univariate analysis (P = 0.04). MVC value is a new indicator of tumor aggressiveness in patients with NSCLC who underwent potentially curative surgery and should be taken into consideration in selecting patients for adjuvant treatment.

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.

Vascular endothelial growth factor expression in human neuroblastoma: up-regulation by hypoxia

Enhanced angiogenesis apparently contributes to the poor clinical outcome of human neuroblastoma, but the mechanisms have remained unclear. We report here that cultured human neuroblastoma cells express a bioactive endothelial cell growth factor indistinguishable from the angiogenesis stimulator vascular endothelial growth factor (VEGF). VEGF is present in neuroblastoma but not vascular endothelial cells, whereas the corresponding VEGF receptors (Flt-1 and Flk-1/KDR) are expressed in endothelial but not neuroblastoma cells. Exposure of neuroblastoma cells to hypoxia induces a marked increase in bioactive VEGF. VEGF is also present in human neuroblastoma specimens, with substantial amounts in apparently hypoxic neuroblastoma cells, eventually accumulating in tumor microvessels. Our results indicate that VEGF (i) is present in human neuroblastomas, (ii) is up-regulated by tumor hypoxia and (iii) may stimulate neuroblastoma angiogenesis by paracrine mechanisms, thereby contributing to the progression of human neuroblastomas. We suggest that inhibition of VEGF activity may represent a novel approach for the therapy of human neuroblastoma.

Randomised placebo-controlled trial of use of topical recombinant bovine basic fibroblast growth factor for second-degree burns

BACKGROUND

Wound healing is a dynamic process that could be accelerated by growth factors. We investigated the effect of recombinant bovine basic fibroblast growth factor (rbFGF) on burn healing in a randomised placebo-controlled trial.

METHODS

We recruited 600 patients with superficial or deep second-degree burns. Patients received 150 AU/cm2 daily topical rbFGF (n=300) or placebo (n=300) plus vehicle. We assessed healing by photography, punch-biopsy, and clinical examination.

FINDINGS

All patients treated with rbFGF had faster granulation tissue formation and epidermal regeneration than those in the placebo group. Superficial and deep second-degree burns treated with rbFGF healed in a mean of 9.9 (SD 2.5) days and 17.0 (4.6) days, respectively, compared with 12.4 (2.7) and 21.2 (4.9) days (p=0.0008 and p=0.0003, respectively). No adverse effects were seen locally or systemically with rbFGF.

INTERPRETATION

rbFGF effectively decreased healing time and improved healing quality. Clinical benefits would be shorter hospital stays and the patient's skin quickly becoming available for harvesting and grafting.

Ultrastructural immunolocalization of basic fibroblast growth factor in mast cell secretory granules. Morphological evidence for bfgf release through degranulation

We previously reported that mast cells (MCs) serve as a source of basic fibroblast growth factor (bFGF), a potent angiogenic and mitogenic polypeptide, suggesting that bFGF may mediate MC-related neovascularization and fibroproliferation. Unlike many other growth factors, bFGF lacks a classic peptide sequence for its secretion, and the mechanism(s) for its release remains controversial. Because MCs release a wide spectrum of bioactive products via degranulation, we hypothesized that MC degranulation may be a mechanism of bFGF release and used ultrastructural immunohistochemistry to test the hypothesis. We reasoned that if bFGF is released through degranulation, it should be localized to MC secretory granules. Human tissues with chronic inflammation and rat/mouse tissues with anaphylaxis were studied. In all tissue samples examined, positive staining (or immunogold particle localization) for bFGF in MCs was predominantly in the cytoplasmic granules. Moderate bFGF immunoreactivity was also found in the nucleus, whereas the cytosol and other subcellular organelles exhibited minimal immunogold particle localization. In contrast, no immunogold particle localization for bFGF was observed in lymphocytes or plasma cells. In rat/mouse lingual tissue undergoing anaphylaxis, immunogold particle localization for bFGF was found not only in swollen cytoplasmic granules but also in the extruded granules of MCs. Three different anti-bFGF antibodies gave similar immunogold particle localization patterns, whereas all controls were negative. These results provide morphological evidence suggesting that, despite the lack of a classic secretory peptide in its structure, bFGF is localized to the secretory granules in MCs and may be released through degranulation.

Influence of intratumoral basic fibroblast growth factor concentration on survival in ovarian cancer patients

Since basic fibroblast growth factor (bFGF) is considered as a potent mitogen that stimulates the growth of ovarian cancer cells, we evaluated the role of bFGF as a prognostic marker in patients with epithelial ovarian cancer. bFGF was quantified from the tumor cytoplasm of 76 patients with FIGO stage I-III ovarian cancer by a human FGF basic immunoassay (R&D Systems). After a mean follow-up period of 42 months, 50 patients were found to be free of tumor while 26 patients had died of the disease. The median bFGF concentration was 352.9 pg/mg (range 27.4-26600 pg/mg). After dichotomization cytoplasmic expression of bFGF was found to be low in 44 tumors (< or =500 pg/mg) and high in 32 tumors (>500 pg/mg). The probability of overall survival was 38.8 and 58.5% in the low bFGF and high bFGF groups, respectively (log-rank P = 0.0066). In multivariate analysis, residual tumor after initial surgery and bFGF, but not histologic grade or stage of the disease, independently influenced the overall survival probability. Furthermore, tumors with high cytoplasmic expression of bFGF revealed a much greater stromal content. Therefore, we hypothesize that bFGF may induce a fibroblastic response which causes tumors with a high bFGF to be less aggressive than those with less stromal tissue.

Tumoural vascularity as a prognostic factor in cancer patients: the evidence continues to grow

Accurate prognostic indicators would help in identifying patients at high risk for recurrence and death. Recent and previous studies indicate that intratumoural microvessel density (iMVD) of invasive breast carcinoma (a measure of tumour angiogenesis) is associated with aggressive tumour growth; iMVD may thus be a valuable prognostic indicator. Moreover, the bulk of accumulating data indicates that microvessel density in the area of most intense neovascularization in invasive breast carcinoma is an independent, significant and accurate prognostic indicator in predicting poorer survival. Such an indicator would be useful in the selection of high-risk patients with breast carcinoma for systemic adjuvant therapy.

Quantitative analysis of microvascular changes in diffuse astrocytic neoplasms with increasing grade of malignancy

Because glioblastoma multiforme (GBM) frequently shows striking, glomeruloid microvascular proliferation (MVP), this tumor has become a strong candidate for anti-angiogenic therapy. However, the efficacy of anti-angiogenic treatment may rather be determined by the extent of classic angiogenesis with the formation of delicate microvascular sprouts. Therefore, this study differentially quantifies the microvascular changes in supratentorial diffuse astrocytic neoplasms by computerized image analysis of histological sections in which the microvessels were highlighted by a combined anti-collagen IV/MIB-1 staining. Four microvascular parameters (number, area, perimeter, diameter), the cellularity of the glial tissue, and the MIB-1 labeling index were assessed in biopsies of astrocytoma (A, n = 13), anaplastic astrocytoma (AA, n = 14), and GBM (n = 20), and in normal cerebral cortex (n = 7) and white matter (n = 7). In As and AAs, the microvascular parameters were not significantly different from each other, and the microvascular changes were generally limited compared with WM and CX. In contrast, in GBMs the microvascular parameters were highly variable, and their overall mean value was significantly increased compared with As and AAs (ranging from 1.3x for vessel diameter to 3.3x for vessel area). Our study indicates that not only glomeruloid MVP, but also classic angiogenesis, occurs mainly and only locally in GBMs. Thus, this study provides evidence that As and AAs are not good candidates for anti-angiogenic therapy. The efficacy of such therapy for GBMs awaits further evaluation.

Immunohistochemical determination of tumor angiogenesis measured by the maximal microvessel density in human prostate cancer

Tumor growth beyond a certain size requires angiogenesis. Experimental evidence shows that once tumors leave the pre-angiogenic phenotype to become angiogenic, metastases often start to evolve. The aim of this study was to develop a reproducible immunohistochemical technique and method to characterize the neovascularization in archival prostate cancer tissue by quantifying the microvessel density (MVD). Archival tumor specimens from 64 consecutively diagnosed prostate cancer patients were immunostained for von Willebrand Factor (vWF), endothelial antigen and for CD31 combined with the use of different digestive enzymes (trypsin and pronase) and heating in a microwave oven. Both the mean and the maximal MVD, and the reproducibility of the method were estimated. Finally, the mean MVD, the maximal MVD, and clinical characteristics were correlated with the crude survival of the patient population. The immunohistochemical staining for vWF to measure the maximal MVD was found to be a reproducible method of characterizing the individual tumor. Both a univariate and a multivariate analysis demonstrated that the maximal MVD, in contrast to the mean MVD, was significantly associated with survival in prostate cancer patients. We conclude that evaluation of angiogenesis by immunostaining the endothelial cells for vWF measured by the MVD in the most vascularized areas of the tumor is a reproducible method of characterizing the individual prostate tumor. Maximal MVD proved to be an independent prognostic parameter useful in conjunction with other known prognostic markers in human prostate cancer.

Vascular endothelial growth factor expression and vascular density as prognostic markers of survival in patients with low-grade astrocytoma

It has long been recognized that some patients with low-grade astrocytoma may survive for many years, whereas in others the disease follows a more malignant course resulting in a short survival time, usually due to malignant transformation into higher-grade tumors.

OBJECT

The aim of this study was to investigate angiogenesis in the initial biopsy specimen of tumor tissue as a biological marker to identify patients with low-grade astrocytoma who are at high risk of malignant tumor transformation or death.

METHODS

Tumor tissue was studied in 74 consecutively treated adult patients in whom a diagnosis of diffuse supratentorial hemispheric histologically proven fibrillary low-grade astrocytoma was made and who underwent surgery between January 1972 and January 1994. Studies were conducted using monoclonal antibodies to the antigens of the proliferation-associated Ki-67 (MIB-1), factor VIII, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and epidermal growth factor (EGF). The overall 5-year survival rate for the entire patient population was 65%, with a median survival time of 7.5 years. The total mean follow-up period was 6.1 years. All tumors showed a low proliferative potential at the time of the initial operation, as demonstrated by an MIB-1 labeling index of less than 1.5%. Patients with more than seven microvessels in tumor tissue (29 cases) had a shorter survival time (mean 3.8 years) than those with seven or fewer microvessels (mean survival 11.2 years). This difference in survival times was significant by univariate (p = 0.001) and stepwise multivariate analyses (p < 0.001). Tumors with a larger number of microvessels also had a greater chance of undergoing malignant transformation (p = 0.001). Similarly, significant staining for VEGF was correlated with shorter survival times when using univariate (p = 0.003) and multivariate (p = 0.008) analyses and with a greater chance of malignant transformation (p = 0.002). Patients with tumors staining positive for VEGF (39 individuals) had a median survival time of 5.3 years, and those with tumors negative for VEGF (35 patients) had a median survival time of 11.2 years. No association was observed between bFGF, EGF, and survival or malignant transformation. The stepwise multivariate analysis included histological and clinical variables simultaneously.

CONCLUSIONS

The authors have shown that microvessel density and VEGF levels are independent prognostic markers of survival in fibrillary low-grade astrocytoma. This finding leads them to propose that fibrillary diffuse low-grade astrocytoma is not a single pathological entity but is composed of a spectrum of tumors with differing propensities to undergo malignant transformation that is at least partly based on their inherent angiogenic potential.

Tumoural vascularity as a prognostic factor in cancer patients: the evidence continues to grow

Accurate prognostic indicators would help in identifying patients at high risk for recurrence and death. Recent and previous studies indicate that intratumoural microvessel density (iMVD) of invasive breast carcinoma (a measure of tumour angiogenesis) is associated with aggressive tumour growth; iMVD may thus be a valuable prognostic indicator. Moreover, the bulk of accumulating data indicates that microvessel density in the area of most intense neovascularization in invasive breast carcinoma is an independent, significant and accurate prognostic indicator in predicting poorer survival. Such an indicator would be useful in the selection of high-risk patients with breast carcinoma for systemic adjuvant therapy.

The inhibition of fibroblast growth factor-2 export by cardenolides implies a novel function for the catalytic subunit of Na+,K+-ATPase

Basic fibroblast growth factor (FGF-2) is one of a select group of proteins that can exit cells through an alternate, endoplasmic reticulum/Golgi apparatus independent exocytic pathway. This alternate pathway has been termed protein export. In an attempt to better understand this process, we have identified a family of related compounds, "cardenolides," that inhibit FGF-2 export. The cardenolides inhibit FGF-2 export in a time and concentration dependent fashion. Inhibition of FGF-2 export is specific in that the cardenolides have no effect on conventional protein secretion as measured by their inability to block release of the secreted protein human chorionic gonadotropin-alpha. Because cardenolides are known to inhibit ion transport activity mediated by Na+,K+-ATPase, we investigated whether there are functional interactions between FGF-2 and their only known molecular target: the alpha-subunit of Na+, K+-ATPase. Export of FGF-2 from COS-1 cells is selectively inhibited when co-transfected with expression vectors encoding the alpha-subunit and FGF-2. Moreover, antibodies to the alpha-subunit specifically co-immunoprecipitate FGF-2 along with the alpha-subunit while conversely, antibodies to FGF-2 specifically co-immunoprecipitate the alpha-subunit along with FGF-2. Finally, the ion transporting activities of the Na+,K+-ATPase can be uncoupled from protein export. Varying the external concentration of K+ has little effect on export of FGF-2. Taken together, these data: 1) identify a novel activity for cardenolides; 2) suggest a previously unknown role for the alpha-subunit of Na+, K+-ATPase in FGF-2 export; and 3) raise the possibility that the alpha-subunit itself may be an integral component of this alternate exocytic pathway mediating translocation of cytosolic FGF-2 to the cell surface.

Tenascin-C expression in the cyst wall and fluid of human brain tumors correlates with angiogenesis

OBJECTIVE

Tenascin-C (TN) is an extracellular matrix glycoprotein with a characteristic six-armed structure. The aim of this study was to determine whether the concentration of TN in the cyst fluid of brain tumors can be used as a marker for angiogenesis and glioma grade.

METHODS

We investigated the expression of TN in the cyst wall and cyst fluid of human brain tumors by immunohistochemistry, immunoprecipitation, and immunoblotting. The tumors included 12 astrocytomas (5 glioblastoma multiforme tumors, 1 anaplastic astrocytoma, 1 low-grade astrocytoma, 4 juvenile pilocytic astrocytomas, and 1 mixed glioma), 2 dysembryoplastic neuroepithelial tumors, 3 craniopharyngiomas, 2 ependymomas, 2 metastatic carcinomas, 3 arachnoid cysts, 1 glial ependymal cyst, and 1 inflammatory cyst.

RESULTS

We detected no expression of TN in the cyst fluids of the ependymomas, craniopharyngiomas, and nonpilocytic low-grade astrocytoma. By contrast, TN was detected in the cyst fluids of all the other tumors. Results of quantitative immunoblotting using a PhosphorImager unit (Molecular Dynamics, Sunnyvale, CA) revealed that, on average, a 5-fold higher signal was observed in the glioblastoma multiforme tumors as compared with the anaplastic astrocytoma, and a 10-fold higher signal as compared with the mixed glioma, juvenile pilocytic astrocytomas, and dysembryoplastic neuroepithelial tumors. Results of TN immunohistochemistry in the astrocytomas correlated with glioma grade, with stronger staining of the hyperplastic vessels and tumor cells being observed in higher grade gliomas. No TN immunoreactivity was detected in the walls of the ependymomas, arachnoid cysts, and glial ependymal cyst that lack hyperplastic vessels, and minimal TN immunoreactivity was observed in the perivascular gliotic rim of the craniopharyngiomas. No TN was detected in the cyst fluid of these cystic processes.

CONCLUSION

The presence of TN in and around the hyperplastic vessels and tumor cells present in the cyst walls of astrocytomas and its deposition in the intratumoral cyst fluid in which angiogenic factors have been detected further suggests a role for TN as an angiogenic modulator. These preliminary results suggest that immunodetection of TN in the tumor cyst fluid may indicate tumor type and grade.

Molecular aspects of neuro-oncology

Detailed understanding of molecular events responsible for brain tumor growth is a prerequisite for the development of effective therapeutic modalities leading to improved prognosis and cure. Advances in molecular biology in the past decades have revolutionized our understanding of cancer, including brain tumors. We have learned that abnormal proliferation, inability of the cells to die and their potential to modify their tissue environment result from accumulation of genetic aberrations. This article reviews genetic mechanisms implicated in the pathogenesis of nervous system tumors, such as unactivation of tumor suppressor and replication error genes, generation of abnormal growth factor loops, alterations of apoptotic pathways and angiogenesis.

Angiogenesis in brain tumors; pathobiological and clinical aspects

Angiogenesis is the outgrowth of new blood vessels from the preexistent vasculature. In 1971, Folkman hypothesized that solid tumors are dependent on angiogenesis for sustained growth and that anti-angiogenic treatment is a potential antineoplastic therapy. Because glioblastoma multiforma (GBM) frequently shows florid microvascular proliferation (MVP), this tumor has been considered since then as a suitable candidate for such treatment that attempts to eradicate or control a neoplasm by interfering with its blood supply. Indeed, in animal models the growth of glioma xenografts can be inhibited by targeting the angiogenic process. However, unlike many glioma xenografts, human infiltrating gliomas such as GBMs have a diffuse infiltrative growth pattern, and preexistent vessels may suffice to provide many tumor cells with much of their blood supply, particularly in the critical peripheral infiltrative margins. Thus, while attractive in concept, anti-angiogenic therapy of GBM must address the anatomic vascular realities of this neoplasm. Even if anti-angiogenic therapy ultimately has a role in infiltrative neoplasms, there are a host of other intracranial neoplasms whose discrete architecture might make them attractive candidates for anti-angiogenic therapy. This review summarizes the angiogenic process in GBM and suggests other types of tumors for which the efficacy of anti-angiogenic therapy might be studied.

Manipulating angiogenesis. From basic science to the bedside

Considerable progress has been made recently in understanding the molecular mechanisms of angiogenesis, which like most other biological processes is the result of subtle and often complex interactions between molecules that have regulatory (eg, cytokines and their receptors) and effector (eg, extracellular matrix, integrins, and proteases) functions. The title of this review was chosen to reflect a recent trend in which knowledge acquired through a molecular/cell biological approach is being rapidly transferred to the clinical setting. As a result, by manipulating angiogenesis either positively or negatively, considerable therapeutic benefit can now be envisaged in physiological and pathological settings in which neovascularization is a prominent component.

The effects of porosity on endothelialization of ePTFE implanted in subcutaneous and adipose tissue

Healing of biomaterial implants varies depending on the type and structure of material and the tissue surrounding the implant. In this study we examined structural differences of 30 microm, 60 microm, and 100 microm expanded polytetrafluoroethylene (ePTFE) using scanning electron microscopy, and we also investigated differences in healing for these three different porosity ePTFE grafts implanted within subcutaneous tissue and adipose tissue. Scanning electron microscopic examination of 30 microm, 60 microm, and 100 microm ePTFE revealed structural differences and differences in fiber density within the internodal space. Circular patches (6 mm in diameter) of 30 microm ePTFE were implanted within subcutaneous tissue and epididymal fat pads of male Sprague-Dawley rats. After 5 weeks, the implants were removed and analyzed for fibrous capsule formation, endothelialization, and for activated monocytes and macrophages in association with the material. Histological evaluation revealed dense fibrous capsule formation surrounding only the 30 microm ePTFE subcutaneous implants. From immunohistochemistry data obtained, we generated an Endothelialization Index (measure of neovascularization) and a Monocyte/Macrophage Index (measure of inflammatory response) for each sample. Consistently, 60 microm ePTFE had the greatest Endothelialization Index at both implant sites while 100 microm ePTFE generally had the largest values for the Monocyte/Macrophage Index. These data indicate that both the structure of the material and the site of implant influence the healing characteristics of ePTFE and suggest that activated monocytes and/or macrophages associated with the implant may inhibit endothelialization of ePTFE.

Angiogenesis as a biologic and prognostic indicator in human breast carcinoma

In this review we describe angiogenesis pathways involved in the development of breast carcinoma. Different assessment techniques for angiogenesis and their optimisation are discussed. Angiogenesis is an important factor for prognosis and will be increasingly important in therapeutic decisions.

Angiogenic factors as tumor markers

The process of angiogenesis plays a critical role in tumor growth and metastasis. Recently, there has been much interest in the possible use of angiogenic growth factors as tumor markers. This paper will review the results thus far of attempts at measuring various angiogenic factors in bodily fluids. In the future, angiogenic factors will most likely be useful as a monitor of therapy and/or a predictor of outcome after cancer has been diagnosed.

Neoangiogenesis and p53 protein in lung cancer: their prognostic role and their relation with vascular endothelial growth factor (VEGF) expression

Following up-regulation of an angiogenesis inhibitor by the wild-type p53 protein proven recently, we have analysed on the one hand the prognostic impact of microvessel count (MC) and p53 protein overexpression in non-small-cell lung carcinoma (NSCLC) progression and, on the other hand, the inter-relation between the microvascular pattern and the p53 protein expression. Moreover, we assessed the expression of vascular endothelial growth factor (VEGF), one of the pivotal mediators of tumour angiogenesis, in order to investigate its relation to p53 protein expression and MC. Tumours from 73 patients resected for NSCLC between March 1991 and April 1992 (median follow-up 47 months, range 32-51 months) were analysed using an immunohistochemical method. In univariate analysis, MC and p53 accumulation were shown to affect metastatic nodal involvement, recurrence and death significantly. Multiple logistic regression analysis showed an important prognostic influence of MC and nodal status on overall (P = 0.0009; P = 0.01) and disease-free survival (P = 0.0001; P = 0.03). Interestingly, a strong statistical association was observed between p53 nuclear accumulation and MC (P = 0.0003). The same inter-relationship was found in non-squamous histotype (P = 0.002). When we analysed the concomitant influence of MC and p53 expression on overall survival, we were able to confirm a real predominant role of MC in comparison with p53. With regard to VEGF expression, p53-negative and lowly vascularized tumours showed a mean VEGF expression significantly lower than p53-positive and highly vascularized cancers (P = 0.02). These results underline the prognostic impact of MC and p53 protein accumulation in NSCLC and their reciprocal inter-relationship, supporting the hypothesis of a wild-type p53 regulation on the angiogenetic process through a VEGF up-regulation.

Influence of investigator experience and microscopic field size on microvessel density in node-negative breast carcinoma

In this study on the determination of intratumoral microvessel density (MVD) in breast cancer, we have investigated the influence of the observer experience and the microscopic field size. We have used the sample set reported on earlier in the J Natl Cancer Inst 87: 1797-1798, 1995. This case-control study has shown a positive association of high MVD and unfavorable outcome when comparing node-negative pT1-2 breast carcinoma (NNBC) patients with a disease-free period of over ten years with those with an early distant relapse. Tumor sections of both outcome groups (favorable: n = 19; unfavorable: n = 19) were immunostained for factor VIII related-antigen (FVIII r-Ag). Microvessels were counted in the areas of most intense vascularization ('hot spots'), both at magnification x 200 (field size of 0.61 square mm) and x 400 (field size of 0.15 square mm), by one inexperienced and three experienced observers. Microphotographs of individual vascular hot spots were analyzed using overlays resembling the two field sizes. The main results obtained are: i) a confirmation of the prognostic value of microvessel density in the case-control sample set (n = 38) was established by all experienced but not by the unexperienced investigator; ii) both at x 200 and x 400 magnification, angiogenesis quantification in vascular hot spots contained prognostic information. The results of this study indicate that the selection of vascular hot spots in tumor sections immunostained for an antigen expressed on endothelial cells is more prone to inter-observer variability and more dependent on training than the counting of the microvessels within predefined hot spots itself. The microscopic magnification and resulting field size do not influence the prognostic significance of MVD in NNBC. This information validates the development of more objective methods of measuring the amount of angiogenesis within malignant tissue. This will allow more accurate implementation of the angiogenesis parameter in multiparametric and prospective prognostic factor studies in NNBC.

Angiogenesis in Endocrine Neoplasms

Angiogenesis promotes the growth of tumors, because it both facilitates oxygenation and nutrient flow, and removes metabolic waste. During the past two decades, as the importance of tumor vascularity became recognized, angiogenesis and the relationship between blood vessels and tumor progression received increasing attention. It was found that isolated tumor tissues failed to expand beyond few millimeters unless vascularized, whereupon vascularization they exhibited a rapid growth. Extensive research focusing on the relationship between tumor proliferation and the formation of new vessels has initially been undertaken to assess the role of angiogenesis in the progression of breast carcinomas. Significant results emerged from these investigations, and similar studies were extended to other tumor types, such as melanomas, cervical and pulmonary carcinomas, and so on. It is of note that angiogenesis as it relates to endocrine tumors has so far been limited to pituitary neoplasms, thyroid carcinomas, and pheochromocytomas. The purpose of the article is to provide a brief review of angiogenesis and to summarize available data regarding its role in the growth off endocrine neoplasms.

Elevated levels of the angiogenic cytokines basic fibroblast growth factor and vascular endothelial growth factor in sera of cancer patients

The concentration of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) was determined in the serum of 90 untreated and 42 treated metastatic cancer patients, including patients with colorectal, breast, ovarian and renal carcinomas, with an enzyme-linked immunosorbent assay (ELISA). Levels higher than the 95th percentile of the concentrations of a control group, i.e. 7.5 pg ml(-1) for bFGF and 500 pg ml(-1) for VEGF, were identified as 'elevated'. One measurement during follow-up was included into the analysis per patient. For 19 treated patients, consecutive serum samples were analysed. Fifty-seven per cent of all untreated patients had elevated serum levels of one or both angiogenic factors. The fraction of patients with elevated serum levels of bFGF and/or VEGF was similar in the different tumour types. Agreement of bFGF levels and VEGF levels, classified in relation to their respective cut-off values, was present in 67% of all patients. Fifty-eight per cent of the patients with progressive disease during treatment compared with 15% of the patients showing response to treatment (chi-squared test P < 0.05) had elevated bFGF and/or VEGF serum levels. When consecutive serum samples were analysed, two-thirds of the patients showing progressive disease had increasing serum levels of the angiogenic factors compared with less than one-tenth of the patients showing response (chi-squared test P < 0.05). The lack of association between the serum bFGF and VEGF levels and the tumour type may suggest an aspecific host reaction responsible for solid tumour-related angiogenesis. The main determinants of the serum bFGF and VEGF concentration are the progression kinetics of the metastatic carcinomas.

Regulation of angiogenesis in malignant gliomas

Gliomas are highly resistant to conventional therapeutic measures, requiring the development of novel treatments. Since gliomas are particularly vascular tumors, one approach involves treatments directed at inhibiting angiogenic mechanisms. Although multiple factors contribute to the ultimate vascularization of any tumor, some are especially relevant to gliomas. Early experimental work directed at inhibiting angiogenic pathways has shown promise toward achieving control of tumor growth. This article focuses on the evidence that angiogenesis and related vascular cell responses play important roles in glioma biology, and reviews those biochemical pathways known through experimentation to be involved in the vascular response to gliomas. Finally, contemporary vessel-targeted approaches that have been used to inhibit glioma growth are discussed.

Markers of tumor angiogenesis: clinical applications in prognosis and anti-angiogenic therapy

Numerous studies in many tumor types have demonstrated that quantitation by microvessel as a measure of angiogenesis is a powerful prognostic tool. However, the ability to exploit tumor angiogenesis as a prognostic marker is limited by the methods currently used for capillary identification and quantitation. This report critically evaluates all aspects of the techniques and their associated problems used for assessing tumor angiogenesis in tissue sections including the area of tumor assessed, the vascular parameter measured, the method of quantitation, the stratification of patients and the practical utility of computer image analysis systems. The potential of angiogenic factors assays, proteolytic enzymes, and cell adhesion molecules as surrogate endpoints for quantifying tumor angiogenesis are discussed and other methods for quantifying tumor angiogenesis are described. The potential clinical applications of these angiogenic markers in prognosis, stratification for adjuvant treatments (both cytotoxic and anti-angiogenic/vascular targeting) and other aspects of patient management is also discussed, particularly design of phase I and II trials.

Elevated levels of basic fibroblast growth factor in patients with limb ischemia

Basic fibroblast growth factor (bFGF), a prototypic member of a family of heparin-binding growth factors, is angiogenic both in vitro and in vivo. Increased levels and activity of bFGF have been documented in a variety of diseases, including tumors. We sought to determine whether bFGF might be similarly elevated in patients with clinical evidence of limb ischemia. Serum was obtained at the time of percutaneous revascularization from patients with symptomatic peripheral vascular disease (46 procedures were performed on 40 patients). An enzyme-linked immunoassay specific for bFGF was used (limit of detection, 1 pg/ml; range in normal subjects, 0 to 5 pg/ml). Among the 40 patients (28 men, 12 women, mean age 70 years) studied, elevated circulating bFGF (> or = 10 pg/ml) was detected in 36 samples (78%); levels ranged from 10 to 310 pg/ml (mean +/- SEM = 62 +/- 12). In 16 (89%) of 18 patients with both rest pain and nonhealing ischemic ulcers, serum bFGF levels were elevated up to 30 times normal values. In conclusion, circulating levels of bFGF are elevated in patients with vascular insufficiency and may reflect a physiologic response to limb ischemia.

Serum basic fibroblast growth factor and vascular endothelial growth factor and tumour growth kinetics in advanced colorectal cancer

BACKGROUND

The development of new microvessels in the surrounding stroma is a prerequisite for tumour progression. Basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) are angiogenic factors expressed in a broad range of human tumours. We have measured the concentrations of both cytokines in the serum of patients with advanced colorectal cancer. We questioned whether these levels are related to the number of tumour sites, the volume of liver and/or lung involvement and the growth kinetics.

PATIENTS AND METHODS

44 untreated colorectal adenocarcinoma patients who had developed metastatic and/or recurrent disease were evaluated. Serum levels of bFGF and VEGF were repeatedly measured using ELISA. The extent of target organ involvement and the kinetics of tumour volume growth were determined on consecutive computer tomography (CT) images.

RESULTS

Patients with a tumour volume doubling time of less than 6 months showed a higher bFGF and VEGF serum level than others, independent of the number of sites involved and the extent of the metastatic disease.

CONCLUSIONS

The data suggest a predictive value of serum bFGF and VEGF levels for the progression of disease in patients with untreated metastatic colorectal cancer. The results corroborate the importance of angiogenesis in the process of tumour growth. The serum levels might prove a useful tool in the quantification of angiogenesis and might be of valuable information in the decision process of initiating palliative chemotherapy. It will be of considerable importance to investigate whether the serum bFGF and VEGF levels have a predictive value on the probability of response to cytotoxic therapy.

Clinical implications of tumor-associated neovascularization and current antiangiogenic strategies for the treatment of malignancies of pancreas

There is now a substantial body of evidence that tumor growth is angiogenesis-dependent, and that neovascularization is also necessary for tumor invasion and metastasis. In addition, the assessment of microvessel count or density in a primary tumor may ultimately prove to be significant and independent prognostic parameter for clinical outcome with respect to tumor recurrence, metastasis, and ultimately, overall patient survival. As our knowledge of the pathways, steps, and factors involved in the underlying pathogenesis of tumor-associate angiogenesis increases, therapeutic agents and modalities aimed at inhibiting angiogenesis by blocking one or more of these steps or factors may be devised and evaluated for their potential to inhibit cancer growth and spread. Ultimately, the inhibition of tumor-associated angiogenesis and associated processes could conceivably form the foundation upon which the treatment of aggressive malignancies is based.

In situ detection of tissue factor in vascular endothelial cells: correlation with the malignant phenotype of human breast disease

Expression of tissue factor (TF) in the endothelium has been observed only rarely in human disease and has been thought to be elaborated on the surface of vascular endothelial cells (VECs) in vitro as an artifact of tissue culture. Using monoclonal antibodies and a novel probe for functional TF, we have localized TF to the VECs (and tumor cells) within the tumors of seven patients with invasive breast cancer but not in the VECs (or tumor cells) of benign tumors from ten patients with fibrocystic disease of the breast. The potent procoagulant TF was shown to be a marker of the initiation of angiogenesis in human breast cancer. Further evidence that the TF was the demonstration of a similar distribution of cross-linked fibrin only in the VECs of the malignant tumors. We interpret these data as further support for the concept that tumor cells can activate nearby VECs and regulate blood vessel growth in vivo. Large clinical pathologic studies will be necessary to determine whether TF is a useful marker for the "switch" to the angiogenic phenotype" in human breast disease and/or correlates with the thromboembolic complications of breast cancer.

Reversion of phenotype of endothelial cells in brain tissue around glioblastomas

With the aim of studying the putative involvement of peritumoral microvessels in the formation of brain edema, small pieces of peritumoral brain tissue were removed from six patients with glioblastoma multiforme submitted to surgery. All patients had cerebral edema, as shown by preoperative C.T. and N.M.R. Control specimens were obtained from four patients undergoing ventriculo-peritoneal shunt. The tissue fragments were fixed in glutaraldehyde-osmium and embedded in Epon. In semi-thin sections observed under light microscopy peritumoral endothelial cells exhibited voluminous cytoplasm and nucleus. Under the electron microscope, capillary cells from glioblastoma patients differed from controls mainly by showing nuclei rich in euchromatin, cytoplasm rich in pinocytotic vesicles and with occasional fenestrations. All these morphological characteristics are compatible with a process of reversion of phenotype of capillaries around glioblastomas to that of periphery as well as an increase in permeability. Both events may be due to diffusion of a tumoral vascular permeability/endothelial growth factor. This peripheral vessel phenotype of peritumoral microvessels supports their participation in the formation of brain edema and may provide a new clue for therapeutic intervention: for example it fits quite well to the known increase in permeability by leukotrienes and decrease in permeability by corticosteroids in tumoral edema.

Microvessel density is a prognostic indicator for patients with astroglial brain tumors

BACKGROUND

Microvessel density in tumors, a measure of angiogenesis, has been shown to be a prognostic indicator that correlates with an increased risk of metastasis in various epithelial cancers and with overall and relapse free survival in patients with breast cancer. Astrocytic brain tumors, particularly malignant astrocytomas, are recognized to be highly vascular tumors with potent angiogenic activity. However, the prognostic significance of microvessel density in these tumors is not known.

METHODS

Sections from formalin fixed paraffin embedded tumor tissue from 93 unselected adult patients with supratentorial astrocytic brain tumors were immunostained for factor VIII-related antigen in order to highlight microvessel endothelial cells. Microvessels were counted at 200x and 400x magnification. Microvessel density was graded as 1+ to 4+ on 1 low power field, without knowledge of clinical outcome. Microvessel count and microvessel grade were correlated with postoperative survival using the Cox proportional hazards regression model. The prognostic significance of microvessel count and grade were also compared with established prognostic indicators, including patient age, Karnofsky performance status, and tumor histology using multivariate analyses.

RESULTS

Both microvessel grade and microvessel count correlated significantly with postoperative survival by univariate analysis in both previously untreated and treated patients. Patients with tumors containing a microvessel Grade of 3+ or 4+ had significantly shorter survival time than patients with a microvessel Grade of 1+ or 2+ (P = 0.0022). Likewise, patients with microvessel counts of 70 or greater had significantly shorter survival than those with microvessel counts of fewer than 70 (P = 0.041). Patient age, Karnofsky performance status, tumor histology, and extent of resection were also correlated with survival by univariate analysis. Microvessel count was further shown to be an independent prognostic indicator by multivariate analyses. There were correlations between microvessel density and patient age and between microvessel density and astrocytic tumor grade.

CONCLUSIONS

These findings support the importance of microvessel density as a prognostic indicator of postoperative survival of patients with astroglial brain tumors. Regional tumor heterogeneity may limit the use of these techniques for routine pathologic examination.

Quantitation and prognostic value of breast cancer angiogenesis: comparison of microvessel density, Chalkley count, and computer image analysis

In some studies of breast cancer, quantitation of immunohistochemically highlighted microvessel 'hot spots' has been shown to be a powerful prognostic tool. However, the antibody used, the number and size of the 'hot spots' assessed, and the stratification of patients into high and low vascular groups vary between studies. Furthermore, little is known about the relationship between microvessel density and other vascular parameters. These uncertainties and the laborious nature of the technique make it unsuitable for diagnostic practice. Both manual and computerized image analysis techniques were used in this study to examine the relationship between microvessel density and the vascular parameters in different sized microscopic fields in a pilot series of 30 invasive breast carcinomas. Automated pixel analysis of immunohistochemical staining, Chalkley point counting, and observer subjective vascular grading were also assessed as more rapid methods of measuring tumour vascularity. A Chalkley count was also performed on a further 211 invasive breast carcinomas. Significant correlations were observed between manual microvessel density and luminal perimeter (r = 0.6, P = 0.0004), luminal area (r = 0.56, P = 0.002), and microvessel number (r = 0.57, P = 0.0009) by computerized analysis. There were also significant correlations between the microscopic hot spots of 0.155 mm2 and 0.848 mm2 for microvessel number (r = 0.81, P < 0.00005), luminal perimeter (r = 0.78, P < 0.00005), and luminal area (r = 0.65, P = 0.0001). In addition, a significant correlation was observed between microvessel density and both subjective vascular grade (P = 0.002) and Chalkley count (P = 0.0001). A significant reduction in overall survival was observed between patients stratified by Chalkley count in both a univariate (P = 0.02) and a multivariate (P = 0.05) analysis in the 211 invasive breast carcinomas. These findings show that Chalkley counting is a rapid method of quantifying tumour angiogenesis and gives independent prognostic information which might be useful in diagnostic practice.

Expression of basic fibroblast growth factor and its receptor in human pancreatic carcinomas

We examined the expression of basic fibroblast growth factor (FGF) and FGF receptor by immunohistochemistry in 32 human pancreatic ductal adenocarcinomas. Mild to marked basic FGF immunoreactivity was noted in 19 (59.4%) of the 32 tumours examined, and 30 (93.3%) of the tumours exhibited a cytoplasmic staining pattern against FGF receptor. The tumours were divided into two groups according to the proportion of positively stained tumour cells: a low expression group (positive cells < 25%) and a high expression group (positive cells > or = 25%). No statistically significant difference in tumour size, differentiation, metastases or stage was found between the low and high basic FGF expression groups. However, a significant correlation was found between FGF receptor expression level and the presence of retroperitoneal invasion, lymph node metastasis, and tumour stage. In addition, low FGF receptor expression was significantly associated with a longer post-operative survival as compared with high FGF receptor expression, whereas there was no significant difference in post-operative survival between the low and high basic FGF expression groups. Increased expression of FGF receptor is correlated with the extent of malignancy and post-operative survival in human pancreatic ductal adenocarcinomas. Thus, overexpression of FGF receptor may prove to be a more useful prognostic marker than basic FGF expression level in pancreatic cancer patients.

The potential role of basic fibroblast growth factor in the transformation of cultured primary human fetal astrocytes and the proliferation of human glioma (U-87) cells

Basic fibroblast growth factor (bFGF) is a potent stimulator of angiogenesis, proliferation, and invasion in human gliomas. To test the hypothesis that bFGF is important in the development of the malignant phenotype of human gliomas, bFGF expression was prospectively modulated in primary human fetal astrocytes and in an established human glioma cell line. Fetal astrocytes were transfected with a vector expressing bFGF modified by the addition of a secretory signal peptide sequence. Two of these bFGF astrocyte clones examined in vitro demonstrated anchorage-independent growth, loss of contact inhibition, and decreased glial fibrillary acidic protein immunoreactivity, changes consistent with cellular transformation. To analyze the inhibition of bFGF expression, phosphorothioated bFGF antisense oligodeoxynucleotides were added to cultures of the U-87 human glioma cell line. The U-87 cell proliferation was inhibited to 70.6 +/- 0.4% of control at 10 mumol/L and to 53.2 +/- 5.6% of control at 20 mumol/L (P < 0.05). Both the 7.0- and 4.0-kilobase bFGF messenger ribonucleic acid transcripts were reduced after exposure to the antisense oligodeoxynucleotide, and cell-associated bFGF protein was reduced by 44%. The sense oligodeoxynucleotide, a negative control, failed to inhibit U-87 proliferation. These data support the concept that bFGF expression could be a key event in glial tumorigenesis that may be necessary for the sustained growth of human gliomas.