Prognostic significance of microvessel density determined by an anti-CD105/endoglin monoclonal antibody in astrocytic tumors: comparison with an anti-CD31 monoclonal antibody

Circulating progenitor cells: a comparison of patients with glioblastoma or meningioma

Blood circulating endothelial cells and circulating hematopoietic progenitor cells (CPCs) are two cell populations that are thought to play important role in angiogenesis. In the present study, we investigated the role of CPCs in patients with brain tumors. We prospectively studied 19 brain tumor patients. Ten healthy individuals were used as controls. Variables that were analyzed included age, sex, Ki-67 index, symptom duration, tumor location, tumor size and preoperative Karnofsky performance status score (KPS). CPCs were determined as CD45(dim)/CD34+/CD133+ in the peripheral blood. Twelve patients had glioblastoma (GBM), 1 patient had a grade II glioma and 6 patients had meningioma. Brain tumor patients had significantly higher CPC levels compared to healthy volunteers. Patients with gliomas had significantly higher CPC levels than patients with meningiomas. In GBM patients no correlation was found between CPC levels and sex, age, Ki-67 index, tumor location, size and KPS. Patients with CPC levels lower than 1,743 cells/ml had a higher progression-free survival but the difference was not statistically significant. Glioma patients had higher CPC levels compared to patients with meningiomas. Larger studies are obviously needed to verify the role of CPC levels in patients with brain tumors.

Nestin: A novel angiogenesis marker and possible target for tumor angiogenesis

Abnormal vasculature, termed tumor vessels, is a hallmark of solid tumors. The degree of angiogenesis is associated with tumor aggressiveness and clinical outcome. Therefore, exact quantification of tumor vessels is useful to evaluate prognosis. Furthermore, selective detection of newly formed tumor vessels within cancer tissues using specific markers raises the possibility of molecular targeted therapy via the inhibition of tumor angiogenesis. Nestin, an intermediate filament protein, is reportedly expressed in repair processes, various neoplasms, and proliferating vascular endothelial cells. Nestin expression is detected in endothelial cells of embryonic capillaries, capillaries of the corpus luteum, which replenishes itself by angiogenesis, and proliferating endothelial progenitor cells, but not in mature endothelial cells. Therefore, expression of nestin is relatively limited to proliferating vascular endothelial cells and endothelial progenitor cells. Nestin expression is also reported in blood vessels within glioblastoma, prostate cancer, colorectal cancer, and pancreatic cancer, and its expression is more specific for newly formed blood vessels than other endothelial cell markers. Nestin-positive blood vessels form smaller vessels with high proliferation activity in tumors. Knockdown of nestin in vascular endothelial cells suppresses endothelial cell growth and tumor formation ability of pancreatic cancers in vivo. Using nestin to more accurately evaluate microvessel density in cancer specimens may be a novel prognostic indicator. Furthermore, nestin-targeted therapy may suppress tumor proliferation via inhibition of angiogenesis in numerous malignancies, including pancreatic cancer. In this review article, we focus on nestin as a novel angiogenesis marker and possible therapeutic target via inhibition of tumor angiogenesis.

Chronic cerebral hypoxia promotes arteriogenic remodeling events that can be identified by reduced endoglin (CD105) expression and a switch in β1 integrins

Chronic cerebral hypoxia leads to a strong vascular remodeling response, though little is known about which part of the vascular tree is modified, or whether this response includes formation of new arterial vessels. In this study, we examined this process in detail, analyzing how hypoxia (8% O(2) for 14 days) alters the size distribution of vessels, number of arteries/arterioles, and expression pattern of endoglin (CD105), a marker of angiogenic endothelial cells in tumors. We found that cerebral hypoxia promoted the biggest increase in the number of medium to large size vessels, and this correlated with increased numbers of alpha smooth muscle actin (α-SMA)-positive arterial vessels. Surprisingly, hypoxia induced a marked reduction in CD105 expression on brain endothelial cells (BECs) within remodeling arterial vessels, and these BECs also displayed an angiogenic switch in β1 integrins (from α6 to α5), previously described for developmental angiogenesis. In vitro, transforming growth factor (TGF)-β1 also promoted this switch of BEC β1 integrins. Together, these results show that cerebral hypoxia promotes arteriogenesis, and identify reduced CD105 expression as a novel marker of arteriogenesis. Furthermore, our data suggest a mechanistic model whereby BECs in remodeling arterial vessels downregulate CD105 expression, which alters TGF-β1 signaling, to promote a switch in β1 integrins and arteriogenic remodeling.

Prognostic importance of markers for inflammation, angiogenesis and apoptosis in high grade glial tumors during temozolomide and radiotherapy

INTRODUCTION

Angiogenesis, inflammation and apoptosis have an important place in the carcinogenesis of high-grade gliomas (HGG). We evaluated the postoperative levels and the prognostic importance of tumor necrosis factor-alpha (TNFα), interleukin 6 (IL6), endoglin (CD105), vascular endothelial growth factor (VEGF), M65 and M30 as markers of inflammation, angiogenesis and apoptosis in patients with HGG.

METHODS AND RESULTS

Postoperative pretreatment sera were collected from 44 newly diagnosed patients with HGG. The control group was also consisted of 44 healthy people. The median age of all patients with HGG was 59 (range: 30-80). Temozolomide concurrent with radiotherapy was given to 37 patients. Thereafter 24 patients received consolidation temozolomide monotherapy. Mean chemotherapy cycle was 4.2. Progression free survival and overall survival were 6 (95% CI; 5.16-6.83) and 16 months (95% CI; 13.07-18.93) respectively in patients treated with concurrent chemoradiotherapy and consolidation chemotherapy. Relative to the control cohort endoglin (p = 0.000) and TNFα (p = 0.000) levels were significantly lower; however VEGF (p = 0.030) levels were higher in the patient group. In contrast, there were no significant change in IL-6 levels and the plasma apoptotic markers M65 (p = 0.085) and M30 (p = 0.292). In separate log rank tests, these biological markers did not correlate with survival.

DISCUSSION AND CONCLUSION

In HGG, a significant decrease in endoglin and TNFα levels was observed, while VEGF levels were significantly increased postoperatively. However, with the power from this patient population, no correlation with survival was observed.

CD105 (Endoglin) exerts prognostic effects via its role in the microvascular niche of paediatric high grade glioma

Paediatric high grade glioma (pHGG) (World Health Organisation astrocytoma grades III and IV) remains poor prognosis tumours, with a median survival of only 15 months following diagnosis. Current investigation of anti-angiogenic strategies has focused on adult glioblastoma multiforme (GBM) with phase III trials targeting vascular endothelial growth factor continuing. In this study we investigated whether the degree of vascularity correlated with prognosis in a large cohort of pHGG (n = 150) and whether different vessel markers carried different prognostic value. We found that CD105 (endoglin) had a strongly significant association with poor prognosis on multivariate analysis (p = <0.001). Supervised hierarchical clustering of genome wide gene expression data identified 13 genes associated with differential degrees of vascularity in the cohort. The novel angiogenesis-associated genes identified in this analysis (including MIPOL-1 and ENPP5) were validated by realtime polymerase chain reaction. We also demonstrate that CD105 positive blood vessels associate with CD133 positive tumour cells and that a proportion of CD105 positive vessel cells demonstrates co-positivity for CD133, suggesting that the recently described phenomenon of vasculogenic mimicry occurs in pHGG. Together, the data suggest that targeting angiogenesis, and in particular CD105, is a valid therapeutic strategy for pHGG.

Neovascularization evaluated by CD105 correlates well with prognostic factors in breast cancers

Angiogenesis is critical for the growth, invasion and metastasis of cancers. Extensive neovascularization and tumor thrombus also correlate with a poor prognosis in breast cancer (BC). Although anti-angiogenic agents have been the therapies of choice for BC, in particular for triple-negative BCs, predictive markers for anti-angiogenic agents are lacking. Microvascular density (MVD) is commonly used to assess the neovascularization in tumors. Compared with pan-endothelial markers such as CD31, CD34 and von Willebrand factor (vWF), CD105 has a higher specificity for MVD in tumor tissues. In this study, we aimed to determine the prognostic value of CD105 in BCs. Paraffin-embedded tissue blocks from 201 BC patients were formed into tissue microarrays. Evaluation of MVD revealed that a median of 11 microvessels determined by CD105 staining correlated significantly with the pathological characteristics of BCs and also with the survival of patients. The expression of CD105 correlated inversely with hormone receptor (HR) expression but positively with Her-2 expression. Univariate analysis indicated that CD105 is a superior predictor of disease-free survival (DFS) in stage I and II diseases; multivariate analysis indicated that only hormone receptors (HRs) are suitable for predicting overall survival (OS) in stage III disease. These findings reveal for the first time that MVD measured by CD105 staining correlates positively with Her-2 expression but negatively with HR expression. The significance of MVD on OS is more apparent in early stage BCs. CD105 has the potential to be used as a predictive marker for anti-angiogenic agents; the targeting of CD105 may also be a potential anticancer strategy.

Assessment of the prognostic significance of endoglin (CD105) in clear cell renal cell carcinoma using automated image analysis

The behavior of clear cell renal cell carcinoma can be difficult to predict. Angiogenesis has proven to be a useful prognostic indicator in different malignancies. Endoglin (CD105) is a new marker of angiogenesis found to have prognostic utility in various tumors. Here, we provide the first automated digital assessment of intratumoral microvascular density in clear cell renal cell carcinoma using endoglin and CD31 and assess their utility as predictors of clinical outcome. Both endoglin and CD31 expression showed association with advanced tumor stage (P = .025 and P = .011, respectively). There was a significant correlation between CD31 and tumor grade (P = .034). Kaplan-Meier survival curves showed that patients with higher endoglin expression had significantly shorter progression-free survival (P = .010). Patients with higher CD31 expression tended to have a worse prognosis, although this was not statistically significant (P = .082). In univariate analysis using endoglin as a continuous variable, increased endoglin was strongly associated with reduced survival (hazard ratio, 1.74; 95% CI, 1.39-2.18; P = <.001). CD31 also correlated with poor outcomes (hazard ratio, 1.52; 95% CI, 1.24-1.86; P = .001). There was no correlation between CD31 and endoglin expression (r = -0.090, P = .541). Receiver operating characteristic analysis showed the area under the curve to be 0.749 for endoglin and 0.550 for CD31. In conclusion, increased endoglin and CD31 expression are associated with a higher tumor stage and decreased progression-free survival. Our automated approach overcomes many limitations of manual quantification. Advances in digital assessment of immunohistochemical markers can be helpful in standardizing the evaluation of tumor biomarkers.

Inhibition of notch signaling in glioblastoma targets cancer stem cells via an endothelial cell intermediate

Glioblastoma multiforme (GBM) is a highly heterogeneous malignant tumor. Recent data suggests the presence of a hierarchical organization within the GBM cell population that involves cancer cells with stem-like behavior, capable of repopulating the tumor and contributing to its resistance to therapy. Tumor stem cells are thought to reside within a vascular niche that provides structural and functional support. However, most GBM studies involve isolated tumor cells grown under various culture conditions. Here, we use a novel three-dimensional organotypic "explant" system of surgical GBM specimens that preserves cytoarchitecture and tumor stroma along with tumor cells. Notch inhibition in explants results in decreased proliferation and self-renewal of tumor cells but is also associated with a decrease in endothelial cells. When endothelial cells are selectively eliminated from the explants via a toxin conjugate, we also observed a decrease in self-renewal of tumor stem cells. These findings support a critical role for tumor endothelial cells in GBM stem cell maintenance, mediated at least in part by Notch signaling. The explant system further highlighted differences in the response to radiation between explants and isolated tumor neurospheres. Combination treatment with Notch blockade and radiation resulted in a substantial decrease in proliferation and in self-renewal in tumor explants while radiation alone was less effective. This data suggests that the Notch pathway plays a critical role in linking angiogenesis and cancer stem cell self-renewal and is thus a potential therapeutic target. Three-dimensional explant systems provide a novel approach for the study of tumor and microenvironment interactions.

Increased blood vessel density and endothelial cell proliferation in multiple sclerosis cerebral white matter

Multiple sclerosis (MS) is primarily considered an inflammatory demyelinating disease, however the role of vasculature in MS pathogenesis is now receiving much interest. MS lesions often develop along blood vessels and alterations in blood brain barrier structure and function, with associated changes in the basement membrane, are pathological features. Nevertheless, the possibility of angiogenesis occurring in MS has received little attention. In this study we used triple label enzyme immunohistochemistry to investigate blood vessel density and endothelial cell proliferation in MS samples (n=39) compared with control tissue to explore evidence of angiogenesis in MS. The results showed that in all MS samples examined blood vessel density increased compared with controls. The greatest increase was found in subacute lesions where numbers of positively stained vessels increased from 43.9+/-8.5% in controls to 84.2+/-13.3% (P=0.001). Furthermore, using an antibody against endoglin (CD105), a specific marker of proliferating endothelial cells, which are characteristic of angiogenesis, we have shown that vessels containing proliferating endothelial cells were more pronounced in all MS tissue examined (normal-appearing white matter, acute, subacute and chronic lesions, P>or=0.027) compared with control and this was greatest in the MS normal-appearing white matter (68.8+/-19.8% versus 10.58+/-6.4%, P=0.003). These findings suggest that angiogenesis may play a role in lesion progression, failure of repair and scar formation.

ROS production and angiogenic regulation by macrophages in response to heat therapy

PURPOSE

It has been well established that inadequate blood supply combined with high metabolic rates of oxygen consumption results in areas of low oxygen tension (<1%) within malignant tumours and that elevating tumour temperatures above 39 degrees Celsius results in significant improvement in tumour oxygenation. Macrophages play a dual role in tumour initiation and progression having both pro-tumour and anti-tumour effects. However, the response of macrophages to heat within a hypoxic environment has not yet been clearly defined.

METHODS

Raw 264.7 murine macrophages were incubated under normoxia and chronic hypoxia at temperatures ranging from 37-43 degrees Celsius. Under normoxia at 41 degrees Celsius, macrophages start to release significant levels of superoxide. The combination of heat with hypoxia constitutes an additional stimulus leading to increased respiratory burst of macrophages.

RESULTS

The high levels of superoxide were found to be associated with changes in macrophage production of pro-angiogenic cytokines. While hypoxia alone (37 degrees Celsius) increased levels of hypoxia inducible factor-1alpha (HIF-1alpha) in macrophages, the combination of hypoxia and mild hyperthermia (39-41 degrees Celsius) induced a strong reduction in HIF-1alpha expression. The HIF-regulated vascular endothelial growth factor (VEGF) decreased simultaneously, revealing that heat inhibits both HIF-1alpha stabilization and transcriptional activity.

CONCLUSION

The data suggest that temperatures which are readily achievable in the clinic (39-41 degrees Celsius) might be optimal for maximizing hyperthermic response. At higher temperatures, these effects are reversed, thereby limiting the therapeutic benefits of more severe hyperthermic exposure.

Blood vessel maturation in human uveal melanoma: spatial distribution of neovessels and mature vasculature

PURPOSE

The aims of this study are (1) to evaluate the spatial distribution of neovessels and mature vessels in human uveal melanoma tumors and (2) to determine whether vessel maturation is associated with the major indicators for poor prognosis.

METHODS

Immunohistochemical analyses were performed on human tissue specimens from enucleated eyes (n = 14) to assess total vessels, neovessels, mature vessels, and cell proliferation. Tumor morphology was analyzed by hematoxylin and eosin and modified periodic acid-Schiff (PAS) staining.The spatial distribution of neovessels and mature vessels was analyzed by immunohistochemistry, and correlated with major indicators of poor prognosis (i.e., aggressive PAS patterns, epithelioid cytology, mitotic figures, extraocular extension, anterior tumor location, ciliary body involvement, large tumor size, cell proliferation, and angiogenic activity).

RESULTS

Neovesseldensity was greater than mature vessel density in apical (p = 0.17), central (p = 0.036), and peripheral (p = 0.31) regions of the tumors, while mature vessel density was greater than neovessel density in basal areas of the tumor (p = 0.47). This pattern indicated that vessel maturation begins at the base of the tumor and later extends to the peripheral and apical regions. The difference between mature and neovessel densities for the apical (-0.8 +/- 1.9) and central areas (-0.8 +/- 1.3) of the tumor was significantly higher than the difference obtained for the basal area (0.3 +/- 1.6; p = 0.014 and p = 0.012, respectively), indicating a higher density of mature vessels compared to neovessels at the base. Statistical correlations were found between mature vessel density and tumor size (r = 0.48, p = 0.084), cell proliferation (r = 0.62, p = 0.042), and mitotic figures (r = 0.76, p = 0.001).

CONCLUSIONS

Significant differences exist in the spatial distribution of mature versus neovessels in human uveal melanoma. Vessel maturation is associated with known clinical and pathologic indicators of poor prognosis (e.g., cell proliferation). Antiangiogenic therapy should be considered for the treatment of ocular malignancies; however, the results of this study indicate that blood vessel maturation heterogeneity may limit the efficacy of vessel targeting agents.

Independent prognostic relevance of microvessel density in advanced epithelial ovarian cancer and associations between CD31, CD105, p53 status, and angiogenic marker expression: A Gynecologic Oncology Group study

OBJECTIVES

The aims of this study were to examine prognostic significance of microvessel density (MVD) in previously-untreated, advanced epithelial ovarian cancer (EOC) and explore associations between MVD and factors that affect angiogenesis.

METHODS

MVD was determined by immunohistochemical expression of CD31 or CD105 in tumor sections from 106 women treated on GOG randomized phase III trials. Average MVD hotspots were quantified by light microscopy at high power (x400) and categorized as low (<upper quartile) or high (>or=upper quartile). Immunoblot expression of MASPIN, THBS-1, bFGF, VEGF, VEGFR-1 and p53 status (mutation and overexpression) was previously determined.

RESULTS

Of 106 evaluable cases, 25% exhibited high CD31-MVD (>24.25 vessels/high power field [HPF]) or high CD105-MVD (>19.25 vessels/HPF). After adjusting for age and stratifying by GOG performance status, stage, cell type, grade, debulking status and treatment regimen, high versus low CD105-MVD was associated with increased risk of disease progression (hazard ratio [HR]=1.873; 95% confidence interval [CI]: 1.102-3.184; p=0.020), but not death (HR=1.125; 95% CI: 0.654-1.935; p=0.670) whereas CD31-MVD was not associated with risk of disease progression (HR=1.578; 95% CI=0.918-2.711; p=0.099) or death (HR=1.678; 95% CI=0.957-2.943; p=0.071). CD31-MVD was correlated with CD105-MVD (p=0.001) and MASPIN (p=0.016). Neither CD31-MVD nor CD105-MVD was associated with p53 status, THBS-1, bFGF, VEGF or VEGFR-1.

CONCLUSIONS

High MVD assessed using CD105, a marker of proliferating endothelial cells and neoangiogenesis, but not CD31 a pan-endothelial marker, appeared to be an independent prognostic factor for worse progression-free survival in women with advanced EOC after adjusting for prognostic clinical covariates.

Specific expression of endoglin (CD105) in endothelial cells of intratumoral blood and lymphatic vessels in pancreatic cancer

Endoglin, a component of the transforming growth factor beta receptor expressed in embryonic vascular endothelial cells, is expressed in vascular endothelial cells in several types of cancer tissues and is involved in tumor angiogenesis. The aim of this study was to analyze the expression pattern of endoglin in pancreatic cancer and assess the involvement of this molecule in cancer progression.

METHODS

Pancreatic cancer and adjacent normal tissues obtained from 36 patients were subjected to immunostaining with anti-endoglin antibody, and the microvessel density (MVD) was assessed based on the number of endoglin-positive vessels.

RESULTS

Endoglin was expressed in endothelial cells of small capillary-like vessels in pancreatic cancer tissues from all 36 patients, and lymphatic endothelial cells in the tumors also expressed endoglin. In contrast, endothelial cells of vascular and lymphatic vessels in normal pancreatic tissue did not express endoglin. Patients with a higher MVD of endoglin-positive vessels had shorter disease-free and overall survival.

CONCLUSIONS

Endoglin is specifically expressed in endothelial cells of small vascular and lymphatic vessels in cancer tissues. The MVD of endoglin-positive vessels may also be a useful prognostic marker in pancreatic cancer patients.

Hypoxia-regulated protein expression, patient characteristics, and preoperative imaging as predictors of survival in adults with glioblastoma multiforme

BACKGROUND

Regions of hypoxia within glioblastoma multiforme (GBM) are common and may influence a tumor's aggressiveness, response to treatment, and the patient's overall survival. In this study, the authors examined 4 markers of hypoxia (hypoxia-inducible factor 1 [HIF-1alpha], glucose transporter 1 [GLUT-1], vascular endothelial growth factor [VEGF], and carbonic anhydrase 9 [CA IX]), cellular proliferation and microvascular density (MVD) indices, extent of surgical resection, and preoperative imaging characteristics and compared them with the overall survival rates of adults with GBM.

METHODS

In this retrospective cohort study, patients who had lower grade astrocytomas were compared with patients who had GBM to verify that the methods used could establish differences between tumor grades. By using preoperative imaging, the amount of necrosis was established versus the overall tumor area. The authors also compared preoperative images with postoperative images to define the amount of tumor resected; and they compared molecular markers, proliferation, MVD, and imaging studies with survival among patients who had GBM.

RESULTS

The hypoxia-regulated molecules (HRMs) and indices for MVD and cellular proliferation were associated significantly with tumor grade. Survival was improved when >or=95% of the tumor was resected. Although the total tumor area was associated with overall survival, no differences were observed when the amount of necrosis or a tumor necrosis index (area of necrosis/area of tumor) was compared with survival. The findings indicated that GLUT-1 and VEGF were correlated with survival after controlling for age.

CONCLUSIONS

Tumor grade was differentiated with HRMs, MVD, and proliferation, but only GLUT-1 predicted survival in this group of patients with GBM. The results suggested that GLUT-1 may be an important independent prognostic indicator.

Endoglin (CD105): a marker of tumor vasculature and potential target for therapy

Endoglin (CD105) is an accessory protein of the transforming growth factor-beta receptor system expressed on vascular endothelial cells. Mutation of the endoglin gene is associated with hereditary hemorrhagic telangiectasias, or Osler-Weber-Rendu syndrome, and has been studied extensively in the context of this disease. The expression of endoglin is elevated on the endothelial cells of healing wounds, developing embryos, inflammatory tissues, and solid tumors. Endoglin is a marker of activated endothelium, and its vascular expression is limited to proliferating cells. Recent studies identified endoglin expression in several solid tumor types, with the level of expression correlating with various clinicopathologic factors including decreased survival and presence of metastases. Attempts to target endoglin and the cells that express this protein in tumor-bearing mice have yielded promising results.

MR imaging of tumor angiogenesis using sterically stabilized Gd-DTPA liposomes targeted to CD105

AIM

To depict tumor angiogenesis via the expression of CD105 in tumor-bearing rats using Gd-DTPA liposomes targeted to CD105 (CD105-Gd-SLs) on MR imaging.

MATERIALS AND METHODS

Three Gd-DTPA liposomal nanoparticles were prepared in our trial: liposomes entrapping Gd-DTPA (Gd-SLs), Gd-SLs conjugated to immunoglobulins (IgG-Gd-SLs) and CD105-Gd-SLs. Forty glioma-bearing rats were randomized into four groups: (a) Gd-DTPA; (b) Gd-SLs; (c) IgG-Gd-SLs; (d) CD105-Gd-SLs. Axial T1WI MRI images were collected at baseline and repeated at 5, 30, 60 and 120 min post-intravenous injection of Gd-DTPA or liposome. Enhancement features and contrast-to-noise ratio of each group were analyzed. After imaging, tumors were resected for immunohistochemistry and immunofluorescence staining to assess vascularity and angiogenesis.

RESULTS

The four groups showed different enhancement features. The enhancement area was restricted for group CD105-Gd-SLs, while diffused for the other three. The degree of enhancement over time varied: group Gd-DTPA showed an early contrast enhancement at instant after injection with a peak at 30 min and a decline to baseline values at 60 min. In group CD105-Gd-SLs, the signal intensity (SI) continuously increased over 120 min. In groups IgG-Gd-SLs and Gd-SLs the SI peaked at 60 min, followed by a minor decrease for IgG-Gd-SLs and a rapid decrease for Gd-SLs almost to baseline. Immunohistochemistry and immunofluorescence showed that the enhancement in the CD105-Gd-SLs group resulted mainly from new microvessels. While in the other three groups, mature microvessels and new microvasculature resulted in the enhancement of the tumor.

CONCLUSION

CD105-Gd-SLs can be used to detect early tumor angiogenesis on MR images. This might provide a means to non-invasively reveal a malignant phenotype of extracerebral F98 tumor and evaluate its progression.

Expression of vascular endothelial growth factor-A and mRNA stability factor HuR in human astrocytic tumors

High-grade astrocytic tumors, such as glioblastoma, possess rich vascular components, which are necessary for their growth. VEGF-A is considered to be the major mediator of angiogenesis in malignant neoplasms including high-grade astrocytic tumors. The upregulation of VEGF-A expression in tumor cells is induced by two mechanisms: the transcriptional activation and the post-transcriptional stabilization of VEGF-A mRNA. While the former mechanism mediated by hypoxia inducible factor-1 alpha (HIF-1alpha) has been revealed, the latter mediated by mRNA stability factor HuR remains unclear in astrocytic tumors. In the present study, we investigated the expression of VEGF-A and mRNA stability factor HuR in supratentorial astrocytic tumors of 27 adults using RT-PCR, ELISA, and immunohistochemistry. Furthermore, we studied the involvement of HuR in the upregulation of VEGF-A expression using malignant astrocytoma cell lines. In higher-grade astrocytic tumors, the level of VEGF-A and microvascular density were elevated, cytoplasmic expression of HuR, which potentially means the protection of VEGF-A mRNA from degradation by ribonucleases, appeared, and they were correlated positively. In in vitro experiments, the inhibition of the cytoplasmic translocation of HuR protein by leptomycin B (LMB) reduced the upregulation of VEGF-A expression in malignant astrocytic tumor cells under hypoxic conditions. These findings suggest that the expression of VEGF-A and cytoplasmic translocation of HuR relates to the histological grade, and that HuR is involved in the upregulation of VEGF-A expression, in human astrocytic tumors.

Immunohistochemical evaluation of the microvascular density through the expression of TGF-beta (CD 105/endoglin) and CD 34 receptors and expression of the vascular endothelial growth factor (VEGF) in oligodendrogliomas

Angiogenesis has been proposed as essential for the growth of solid tumors. The determinants of this process, the growth factors and the vascular endothelial receptors have brought a potential in the tumor prognostic determination as well as perspectives of "targets" for antiangiogenic therapy. In oligodendrogliomas (OL), angiogenesis is little known and/or has generated conflicting results. In order to clarify angiogenesis in OL, we have evaluated the immunohistochemical expression of vascular endothelial growth factor (VEGF) and the microvascular density (MVD) through the expression of TGF-beta (CD105/endoglin) (MVD-CD105) and CD34 (MVD-CD34) receptors using the Chalkley point method in 30 OL. No significant immune reaction was found for the VEGF. There was expression in <10% of tumor cells and/or staining of weak intensity in 15 (50.0%), >10% of cells and moderate intensity staining in 1 (3.33%), and negative expression in 14 (46.67%). If present, the expression was restricted to tumor and endothelial cells. Our findings suggest that VEGF has little influence on OL angiogenesis. All specimens showed CD105 and CD34 expression in the intratumor vascular endothelium, suggesting involvement of CD105 in OL angiogenesis. The mean +/- SD MVD-CD105 and MVD-CD34 were 10.83 +/- 2.24 and 11.00 +/- 2.76 in OL (P = 0.086; r = 0.319); 10.00 +/- 2.00 and 10.40 +/- 3.02 in OL grade II (n = 15) (P = 0.547; r = 0.105), and 11.67 +/- 2.22 and 11.53 +/- 2.45 in OL grade III (n = 15) (P = 0.817; r = 0.551), respectively. The absence of correlation between DMV-CD105, DMV-CD34 and tumor grades suggests that anti-CD105 and anti-CD34 antibodies have different vascular specificities. MVD-CD105 was greater in OL grade III than in OL grade II (P = 0.0032), indicating an increase in the vascular neoformation, something which must be evaluated as a possible prognostic factor in OL. Both TGF-beta and CD105 bring perspectives as "targets" for antiangiogenic treatments in OL.

Correlative evidence that tumor cell-derived caveolin-1 mediates angiogenesis in meningiomas

Since it has recently been reported that caveolin-1 (cav-1) may favor the progression of prostatic and renal cancers by stimulating tumor neoangiogenesis, we thought it of interest to analyze the correlation between cav-1 expression and tumor microvessel density (MVD) in meningiomas. In the present study we quantified cav-1 expression by immunohistochemistry and used CD105 immunohistochemical staining to measure MVD. Sixty-two formalin-fixed, paraffin-embedded, surgically resected meningiomas were submitted to the analysis. On the basis of cav-1 immuno-expression, cases were subdivided into meningiomas displaying a low (n = 34) and a high (n = 28) cav-1 immuno-expression, respectively. Mann-Whitney test showed that a significantly higher MVD was present in the cases with a high cav-1 expression than in those with a low expression (mean 24.44 vs. 41.28 microvessels/mm(2)) (P = 0.0001). Moreover, Spearman test revealed a significant positive correlation between cav-1 rate of expression and MVD counts in the meningiomas of our series (r = 0.390; P = 0.0023). Therefore, our study demonstrates the existence of an association between cav-1 expression and neoangiogenesis in meningiomas, suggesting that cav-1 may mediate the progression of these tumors by stimulating the angiogenic process. Besides, it is known that the progression of meningiomas is paralleled by an increase in MVD. The clarification of cav-1 role in the neoangiogensis of meningiomas may open new insights about the possibility of novel therapeutic strategies in these neoplasias.

Antiangiogenic therapy and surgical practice

Background

Antiangiogenic therapy has become a reality with the recent introduction of bevacizumab, a monoclonal antibody against vascular endothelial growth factor.

Methods

Relevant medical literature from PubMed, National Institute for Health and Clinical Excellence and National Institutes of Health websites to August 2007 was reviewed.

Results and conclusions

Although often described as the fourth modality of treatment after surgery, radiotherapy and chemotherapy, many antiangiogenic drugs have failed to live up to expectations. Nevertheless, research continues and there are reasons to believe that antiangiogenic therapy may yet have a future in the clinical setting.

Transforming growth factor-beta binding receptor endoglin (CD105) expression in esophageal cancer and in adjacent nontumorous esophagus as prognostic predictor of recurrence

BACKGROUND

We hypothesized that the potent neovascularization marker endoglin (CD105), by differentially highlighting a subset of microvessels (MV) in esophageal cancer (EC), could provide better prognostic/therapeutic information than the panendothelial marker CD34, which also highlights MV.

METHODS

Endoglin messenger ribonucleic acid (mRNA) expression in normal, malignant, and adjacent nontumorous esophagus tissue was quantified by real-time reverse-transcription polymerase chain reaction (RT-PCR). Sections of formalin-fixed, paraffin-embedded tissues were analyzed immunohistochemically for CD105 and CD34. MV density was counted following a standard protocol. Circulating soluble endoglin levels were determined in patient and control sera, and compared with clinical outcome.

RESULTS

CD105 mRNA was upregulated by a median factor of 2.89 in ECs versus controls. In 28% of patients, CD105 mRNA was upregulated by a median factor of 2.65 in adjacent non-tumorous versus normal tissue. In tumor tissues, CD105 was stained negatively or positively only in a subset of MV. CD34 always showed positive extensive MV staining. In adjacent nontumorous esophagus, CD105 rarely showed diffuse MV staining, while CD34 stained blood-vessel endothelial cells in all non-neoplastic tissue. CD105 expression was high in residual highly dysplastic Barrett's-type mucosa associated with some adenocarcinomas. No statistically significant difference in endoglin serum levels appeared between patients and normal subjects. Correlation with clinicopathological data showed higher intra-tumor MV-CD105+ scores at more-advanced clinical stages. High-scoring MV-CD105+ patients had significantly shorter disease-free and overall survival; MV-CD34+ density was not survival related. Diffuse CD105 expression in adjacent nontumorous esophagus predicted poorer disease-free and overall survival.

CONCLUSIONS

Our findings could help identify EC patients who may benefit from targeted anti-angiogenic therapies.

Density of microvessels positive for CD105 (endoglin) is related to prognosis in meningiomas

Microvessel density (MVD) is considered to be a prognostic marker in many tumours. Nevertheless, conflicting results were achieved regarding its prognostic role in meningiomas when it was quantified through pan-endothelial markers such as CD34, CD31 or Factor VIII. In the present study, MVD was assessed in meningiomas through the specific marker for neo-angiogenesis CD105. Fifty-four formalin fixed, paraffin embedded, surgical cases of meningiomas (WHO 28 grade I and 26 grade II) as well as ten normal leptomeningeal samples were submitted to immunohistochemical analysis for CD105. CD34 immuno-expression was also evaluated on consecutive parallel sections. For each case, MVD was estimated in terms of number of vessels/mm(2). CD105 was not evidenced in normal samples, whereas it was demonstrated in the vessels within 14/28 WHO grade I cases and within 24/26 WHO grade II meningiomas. On the contrary, CD34 antibody stained blood vessels in both normal and neoplastic samples; moreover, in each case, it stained more microvessels than CD105 antibody (25.33 +/- 21.16 vs. 50.72 +/- 26.75). Higher CD105 counts were significantly correlated with higher histological grade and Ki-67 LI > 4%. No statistical significant correlations were encountered between MVD measured by either CD105 and CD34 and sex, age, site of tumour or extent of surgical resection. CD105-MVD, but not CD34-MVD, showed an inverse significant correlation with overall survival and recurrence-free survival. In conclusion, our study suggests the higher specificity of CD105 in comparison to pan-endothelial markers in the evaluation of meningioma neo-angiogenesis, and its higher prognostic significance. CD105 might serve as a target for therapeutic approaches blocking blood supply in meningiomas.

Inhibition of tumor growth by a truncated and soluble form of melanotransferrin

Melanotransferrin is a glycoprotein expressed at the cell membrane and secreted in the extracellular environment. Recombinant truncated form of membrane-bound melanotransferrin (sMTf) was reported to exert in vitro anti-angiogenic properties. Here we show that sMTf treatment leads to a 50% inhibition of neovascularization in Matrigel implants when stimulated by growth factors. Using a glioblastoma xenograft model, we demonstrate that sMTf delivery at 2.5 and 10 mg/kg/day by micro-osmotic pump inhibits tumor growth by 73% and 91%, respectively. In a lung carcinoma xenograft model, sMTf treatment at 2.5 and 10 mg/kg/day impeded tumor growth by 87% and 97%. Furthermore, subcutaneous glioblastoma and lung carcinoma tumors from mice treated with 10 mg/kg/day of sMTf present insignificant growth toward the study. In association with a reduction in endoglin mRNA expression, the hemoglobin content decreased by half in sMTf-treated glioblastoma tumors. In vitro experiments revealed that NCI-H460 cells treated with sMTf display an inhibition in their invasive capabilities with a concomitant reduction in the expression of the low-density lipoprotein receptor protein and urokinase plasminogen activator receptor. Altogether, our results demonstrate that sMTf exerts anti-cancer and anti-angiogenic activities, suggesting that its administration may provide novel therapeutic strategies for the treatment of cancer.

Significance of neo-angiogenesis and immuno-surveillance cells in squamous cell carcinoma of the tongue

Background

Neo-angiogenesis is an essential process in physiological and pathological conditions. However, it is a complex process. Several studies demonstrated that intra-tumoural microvessel number is a significant predictor of metastasis and clinical outcome in many tumours, including oral malignancies. The immuno-surveillance cells, mast cells and eosinophils are implicated in the biological behaviour of tumours. Nevertheless, their function in tissues is uncertain. Mast cells are involved in homeostatic regulation of blood vessels as well as host defence. In some malignancies, high mast cell density has been found to correlate with favourable prognosis. However, others reported unfavourable associations. Tumour associated tissue eosinophilia is a well-known phenomena. It has been associated with good and poor prognosis. However, the role of eosinophils in tumours remains controversial. Therefore, this study was designed to investigate the prognostic value of microvessel, mast cell and eosinophil densities in the context of clinico-pathological parameters and survival in squamous cell carcinoma of the tongue.

Materials and Methods

Anti-CD105 and anti-tryptase monoclonal antibodies were utilized to highlight and count microvessels and mast cells respectively in 81 cases of tongue squamous cell carcinoma. Eosinophils were demonstrated using carbol chromotrope histochemical stain. The densities were counted per mm2 and correlated with patients’ outcome and other clinico-pathological parameters using non-parametric tests and student's t-test. Clinically, the cases were divided into 4 main groups depending on survival time, lymph-node or distant metastasis.

Results

The 5 year survival was significantly lower in patients with a low mast cell density than those with a high density (p=0.006, Kruskal-Wallis test). The survival group-A demonstrated significantly higher mast cell and microvessel numbers than group-D (p=0.007, student's t-test) respectively. Patients with well- differentiated squamous cell carcinoma had significantly higher numbers of mast cells when compared to patients with poorly differentiated squamous cell carcinoma (p<0.05, student's t-test). The lymph node involvement correlation between the survival group-A and survival group-D was also significant (p=0.001, Mann-Whitney U test).

Conclusion

Data from this study indicates that accumulating mast cells in tumours play a part in inhibiting tumour progression and is potentially angiogenic in tumours.

Endoglin (CD 105) is expressed on endothelial cells in the primary central nervous system lymphomas and correlates with survival

Endoglin (CD105) is predominantly expressed on the cellular lineages within the vascular system and it is overexpressed on proliferating endothelial cells that participate in neoangiogenesis, with a weak or negative expression in the vascular endothelium of normal tissues. To investigate the correlation between the CD105 expression and possible prognostic markers or progression in the primary central nervous system lymphomas (PCNSLs), the present study assessed 26 cases of PCNSL by immunostaining for CD105 and CD34. Intratumoral microvessel density (IMVD) was determined in the hotspots and interfaces at a magnification of x200. According to the mean value, the patients were classified into lower-IMVD and higher-IMVD groups. When CD34 was used as a marker of angiogenesis, the survival rates of these two groups demonstrated no significant difference. In contrast, when CD105 was used as a marker of angiogenesis, the survival rate of the lower-IMVD group was significantly higher than that for the higher-IMVD group (P < 0.01). In the group of CD34-immunostained vessels, no difference was observed in IMVD between the hotspots and interfaces (P = 0.31). In the group with CD105-immunostained vessels, a greater IMVD was observed in the hotspots than in the interfaces (P < 0.01). These results suggested that the growth of PCNSLs was dependent on angiogenesis, that IMVD as determined by anti-CD105 monoclonal antibody was a reliable prognostic marker in PCNSLs, and that PCNSLs may therefore not require sufficient neoangiogenesis at the start of PCNSLs, however, it may instead require a higher rate of neoangiogenesis as they infiltrate and destroy the brain parenchyma.