Levels of soluble angiogenin in chronic myeloid malignancies: clinical implications

Angiogenic Molecules in Hodgkin's Disease: Results from Sequential Serum Analysis

Increased angiogenic activity has been demonstrated in lymphoproliferative diseases including Hodgkin's disease. In the current study, the levels of circulating angiogenic molecules in 60 Hodgkin's patients were determined prior to and after treatment and correlated to disease stage and prognostic score. Hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF), interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) were increased in Hodgkin's patients in comparison to healthy controls (p<0.001). Angiogenin and angiopoietin-2 levels did not differ from controls. HGF, VEGF, TNF-α and angiogenin decreased significantly in Hodgkin's patients after standard treatment (p<0.001 for HGF, p<0.05 for VEGF, TNF-α and angiogenin). Furthermore, HGF and TNF-α increased with advancing stage of disease (p<0.05). HGF and VEGF correlated significantly with IL-6 (r=0.56, p<0.0005 and r=0.57, p<0.001 respectively). In conclusion, Hodgkin's disease displays an angiogenic activity as depicted by the increased serum levels of a number of angiogenic cytokines. HGF seems to be the prominent molecule in Hodgkin's disease, which may be used to monitor the disease status and the response to treatment.

Fluorescence Sensing Using DNA Aptamers in Cancer Research and Clinical Diagnostics

Among the various advantages of aptamers over antibodies, remarkable is their ability to tolerate a large number of chemical modifications within their backbone or at the termini without losing significant activity. Indeed, aptamers can be easily equipped with a wide variety of reporter groups or coupled to different carriers, nanoparticles, or other biomolecules, thus producing valuable molecular recognition tools effective for diagnostic and therapeutic purposes. This review reports an updated overview on fluorescent DNA aptamers, designed to recognize significant cancer biomarkers both in soluble or membrane-bound form. In many examples, the aptamer secondary structure switches induced by target recognition are suitably translated in a detectable fluorescent signal using either fluorescently-labelled or label-free aptamers. The fluorescence emission changes, producing an enhancement (“signal-on”) or a quenching (“signal-off”) effect, directly reflect the extent of the binding, thereby allowing for quantitative determination of the target in bioanalytical assays. Furthermore, several aptamers conjugated to fluorescent probes proved to be effective for applications in tumour diagnosis and intraoperative surgery, producing tumour-type specific, non-invasive in vivo imaging tools for cancer pre- and post-treatment assessment.

Three decades of research on angiogenin: a review and perspective

As a member of the vertebrate-specific secreted ribonucleases, angiogenin (ANG) was first isolated and identified solely by its ability to induce new blood vessel formation, and now, it has been recognized to play important roles in various physiological and pathological processes through regulating cell proliferation, survival, migration, invasion, and/or differentiation. ANG exhibits very weak ribonucleolytic activity that is critical for its biological functions, and exerts its functions through activating different signaling transduction pathways in different target cells. A series of recent studies have indicated that ANG contributes to cellular nucleic acid metabolism. Here, we comprehensively review the results of studies regarding the structure, mechanism, and function of ANG over the past three decades. Moreover, current problems and future research directions of ANG are discussed. The understanding of the function and mechanism of ANG in a wide context will help to better delineate its roles in diseases, especially in cancer and neurodegenerative diseases.

Serum Angiopoietin Levels are Different in Acute and Chronic Myeloid Neoplasms: Angiopoietins do not only Regulate Tumor Angiogenesis

Molecular balance between Angiopoietin-1 (Ang-1) and Angiopoietin-2 (Ang-2) has important effects in tumor angiogenesis. Ang-2 was shown to be elevated and proved to be a prognostic factor in acute myeloid leukemia (AML). To date studies revealed increased angiogenesis in bone marrows (BMs) of both myeloproliferative neoplasm (MPN) and AML patients. We conducted this study to demonstrate circulating levels of Ang-1 and Ang-2 in MPN patients since no data exists in literature. Thirty-three newly diagnosed MPN, 27 newly diagnosed AML patients and 25 controls (HC) were enrolled and Angiopoietin levels were determined with ELISA. We found that Ang-1 levels were higher whereas Ang-2 levels were lower in MPN and HC when compared to AML. Our results suggest that though angiogenesis is increased in both AML and MPN, angiopoietin serum level profile of the two diseases are different, and MPN patients have similar Ang-1 and Ang-2 levels as HC. We conclude that, according to our results Ang-1 and Ang-2 do not only regulate tumor angiogenesis and the difference between angiopoietin levels of acute and chronic myeloid neoplasms could be a reflection of other effects of these growth factors on tumor malignancy.

Circulating endothelial cells are increased in chronic myeloid leukemia blast crisis

We measured circulating endothelial precursor cells (EPCs), activated circulating endothelial cells (aCECs), and mature circulating endothelial cells (mCECs) using four-color multiparametric flow cytometry in the peripheral blood of 84 chronic myeloid leukemia (CML) patients and 65 healthy controls; and vascular endothelial growth factor (VEGF) by quantitative real-time PCR in 50 CML patients and 32 healthy controls. Because of an increase in mCECs, the median percentage of CECs in CML blast crisis (0.0146%) was significantly higher than in healthy subjects (0.0059%, P<0.01) and in the accelerated phase (0.0059%, P=0.01). There were no significant differences in the percentages of CECs in chronic- or active-phase patients and healthy subjects (P>0.05). In addition, VEGF gene expression was significantly higher in all phases of CML: 0.245 in blast crisis, 0.320 in the active phase, and 0.330 in chronic phase patients than it was in healthy subjects (0.145). In conclusion, CML in blast crisis had increased levels of CECs and VEGF gene expression, which may serve as markers of disease progression and may become targets for the management of CML.

Angiogenic factors in chronic lymphocytic leukaemia (CLL): Where do we stand?

The role of angiogenesis in haematological malignancies such as chronic lymphocytic leukaemia (CLL) is difficult to envision, because leukaemia cells are not dependent on a network of blood vessels to support basic physiological requirements. Regardless, CLL cells secrete high levels of major angiogenic factors, such as vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and platelet derived growth factor (PDGF). Nonetheless, it remains unclear how most angiogenic factors regulate accumulation and delayed apoptosis of CLL cells. Angiogenic factors such as leptin, granulocyte colony-stimulating factor (G-CSF), follistatin, angiopoietin-1 (Ang1), angiogenin (ANG), midkine (MK), pleiotrophin (PTN), progranulin (PGRN), proliferin (PLF), placental growth factor (PIGF), and endothelial locus-1 (Del-1), represent novel therapeutic targets of future CLL research but have remained widely overlooked. This review aims to outline our current understanding of angiogenic growth factors and their relationship with CLL, a still uncured haematopoietic malignancy.

Emerging roles of endoglin/CD105 and angiogenic cytokines for disease development and progression in multiple myeloma patients

Angiogenesis is an essential process for the expansion of multiple myeloma (MM), in which many angiogenic factors participate. Endoglin (CD105) is a transforming growth factor-β co-receptor, being mainly expressed in angiogenic endothelial cells and has been used as a marker of tumor angiogenesis, having prognostic potential. The aim of the study was to evaluate serum levels of soluble CD105 (sCD105) in MM patients, both during diagnosis and after effective conventional chemotherapy, in the plateau phase, and to correlate them with the clinical stage of the disease, as well as with the known angiogenic factors vascular endothelial growth factor, angiogenin and interleukin-18 (IL-18). Serum levels of the aforementioned factors were measured, by enzyme-linked immunosorbent assay, in 56 newly diagnosed MM patients, in 35 of them who entered plateau phase and in 24 healthy controls. Bone marrow aspirations were also performed in all patients to determine plasma cell infiltration. All measured cytokines were higher in MM patients compared with controls and with advancing disease stage (p < 0.001 for all cases). Furthermore, the values of all factors decreased significantly in the plateau phase (p < 0.001 for all cases). Serum levels of sCD105 correlated with the other angiogenic cytokines, whereas only serum levels of angiogenin had prognostic value for the survival. In conclusion, CD105 and the angiogenic cytokines vascular endothelial growth factor, angiogenin and IL-18, seem to have emerging roles both in angiogenesis and tumor growth in MM.

Effects of basic fibroblast growth factor on angiogenin expression and cell proliferation in H7402 human hepatoma cells

Hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. Basic fibroblast growth factor (bFGF), which is highly expressed in developing tissues and malignant cells, regulates cell growth, differentiation, and migration. Its expression is essential for the progression and metastasis of HCC. This study aims to investigate the effects of bFGF on the expression of angiogenin, another growth factor, which plays an important role in tumor angiogenesis, and on cell proliferation in H7402 human hepatoma cells. The bFGF sense cDNA or antisense cDNA was stably transfected into H7402 cells. Genomic DNA PCR analysis demonstrated that human bFGF sense cDNA or antisense cDNA was inserted into the genome. Furthermore, the expression of bFGF and angiogenin was examined by RT-PCR and Western blot assays. MTT and colony formation assays were employed to determine cell proliferation. Stable bFGF over-expressing and under-expressing transfectants were successfully established. Expression of angiogenin was decreased in the over-expressing bFGF cells (sense transfectants) and was increased in the under-expressing bFGF cells (antisense transfectants). Cell proliferation increased in the bFGF sense transfectants and decreased in the bFGF antisense transfectants. These results demonstrated that the endogenous bFGF may not only negatively regulate the angiogenin expression but also contribute to the overall cell proliferation in H7402 human hepatoma cells. This study may be helpful in finding a potential therapeutic approach to HCC.

Serum angiogenin levels predict treatment response in patients with stage IV melanoma

This work was conducted to find out new potential serum markers and study their role as predictive factors in patients with metastatic melanoma. Serum samples from 68 patients with stage IV malignant melanoma were collected just before current treatment and screened for 79 different cytokines by using a multi-cytokine array. Angiogenin, which is a protein capable of promoting angiogenesis, was found to be markedly elevated among a sub-group of patients with progressive disease (PD) and thus was subjected to further analysis. The mean serum angiogenin level was 270 ng/ml and the median 236 ng/ml (STD 163 ng/ml). Concentrations were significantly higher among men than in women (P = 0.031), whereas patient's age, site of the primary tumour, Clark's or Breslow's classifications were not associated with angiogenin levels. Patients with only lymph node metastases had markedly lower angiogenin levels than those with metastases at other sites (P = 0.05). High angiogenin levels were significantly (P = 0.015; Kruskal-Wallis) associated with poor treatment response with chemoimmunotherapy. Treatment-related survival (TRS) was shorter (10 months) in patients with above-median values than in those with below-median levels (19 months, P = NS). Cox multivariate regression model was used to control for the confounding by the classical prognostic factors of melanoma (age, sex, disease burden, performance score, site of metastases). Disease burden was the only variable that remained in the model as a significant independent predictor of TRS (P = 0.044). These data suggest that serum angiogenin levels might be of predictive value in the evaluation of treatment response for patients with stage IV melanoma.

Angiogenin: a review of the pathophysiology and potential clinical applications

Angiogenin is a member of the ribonuclease (RNase) superfamily: enzymes of innate substrate specificity, but divergent functional capacities. Angiogenin is a normal constituent of the circulation and contained in a vasculature that rarely undergoes proliferation, but in some physiological and pathological conditions its levels increase in blood, promoting neovascularization. Hence, angiogenesis is a common pathophysiological attribute of angiogenin. In malignant disease, the most studied pathological state in regard to angionenin, abnormally high levels are seen, which may be of prognostic significance. Angiogenin has also been studied in other non-malignant pathological states. The aim of this review article is to provide an overview of the biochemistry and physiology of angiogenin, specifically in relation to the human pathological states where angiogenin has been implicated and finally, its potential clinical applications.

Influence of angiogenin on the growth of A375 human melanoma cells and the expression of basic fibroblast growth factor

Angiogenin was isolated as a tumor angiogenic factor solely on the basis of its angiogenic activity. Its expression is essential for melanoma progression and metastasis. Many studies have mainly focused on how it induces angiogenesis, which allows further melanoma growth and metastasis. Here, we investigated the effects of angiogenin on melanoma cell growth and studied its influence on the expression and function of the basic fibroblast growth factor. We transfected the angiogenin gene in the sense and antisense orientation into A375 cells, and obtained stable angiogenin under-expressing and over-expressing transfectants. We found that in the angiogenin antisense transfectants, the cell proliferation was decreased and the basic fibroblast growth factor-induced cell proliferation was inhibited, but the expression of basic fibroblast growth factor was increased. In contrast, in the angiogenin sense transfectants, the cell proliferation was increased, and the basic fibroblast growth factor-induced cell proliferation was also increased. The expression of basic fibroblast growth factor, however, was decreased. In conclusion, we demonstrated that, besides its angiogenic activity, angiogenin also directly contributes to A375 cell proliferation and is required for the basic fibroblast growth factor to induce cell proliferation. We also demonstrated that the endogenous angiogenin expression levels affect the expression of basic fibroblast growth factor in A375 cells. By targeting angiogenin, therefore, one may find a potential therapeutic approach to human malignant melanoma.

Genetic and environmental determinants of circulating levels of angiogenin in community-based sample

BACKGROUND

Measurement of angiogenin in plasma provides important prognostic and diagnostic information in variety of malignancies and may even correlate with cancer's progression. Nevertheless, nowadays, specific physiological mechanisms of this protein action as well as major factors regulating its circulating levels normally and in pathology are still poorly understood. The main objectives of this study were to examine the contribution of a number of endogenous factors, such as sex, age, body size and genetic effects on the production of angiogenin in apparently healthy individuals, and to assess the correlations in circulating levels between angiogenin and other molecules involved in angiogenesis.

METHODS

The plasma levels of angiogenin and each of the additional cytokines [interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-alpha), transforming growth factor-beta (TGF-beta), macrophage-colony stimulating factor (M-CSF), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), soluble intercellular adhesion molecule-1 (sICAM)] were determined by enzyme-linked immunoassay in a large family based sample.

RESULTS

Angiogenin levels were significantly higher in man than in women (360.64 +/- 104.04 ng/ml vs. 322.15 +/- 100.34 ng/ml, P < 0.01) and significantly correlated with age (P < 0.01) in both sexes. Genetic analysis showed that adjusted for potential covariates, 37.4 +/- 7.1% of angiogenin variation was attributable to putative genetic factors. The results of our study revealed that angiogenin concentrations were positively and significantly (P < 0.05) associated with sICAM, IL-6, TNF-alpha and M-CSF levels in the female cohort.

CONCLUSIONS

Our data provide reliable evidence for the substantial role of genetic factors in the determination of the phenotypic variability of angiogenin plasma levels. These findings of our study, including circulating angiogenin reference limits in healthy population and its correlation with angiogenic cytokines, may be of importance in determination of early stages of pathological angiogenesis.

Clinical correlation of bone marrow microvessel density in essential thrombocythemia

The aim of this study was to investigate the prognostic relevance of angiogenesis expressed as bone marrow microvessel density (MVD) in 40 patients with essential thrombocythemia (ET). Bone marrow MVD was visualized in paraffin tissue sections using immunohistochemical staining for CD34 protein. Increased MVD of bone marrow specimens was not significantly correlated with clinical (sex, age, microvascular disturbances, liver and spleen size, complications, treatment or no before biopsy), laboratory (peripheral blood count), bone marrow histopathological parameters (cellularity, megakaryocyte clumping and reticulin fibrosis) and overall survival. These preliminary findings suggest that angiogenesis has no prognostic value in patients with ET.

Alpha-actinin-2, a cytoskeletal protein, binds to angiogenin

Angiogenin is an angiogenic factor which is involved in tumorigenesis. However, no particular intracellular protein is known to interact directly with angiogenin. In the present study, we reported the identification of alpha-actinin-2, an actin-crosslinking protein, as a potential angiogenin-interacting partner by yeast two-hybrid screening. This interaction was confirmed by different approaches. First, angiogenin was pulled down together with His-tagged alpha-actinin-2 by Ni(2+)-agarose resins. Second, alpha-actinin-2 was coimmunoprecipitated with angiogenin by anti-angiogenin monoclonal antibody. Third, the in vivo interaction of these two proteins was revealed by fluorescence resonance energy transfer analysis. Since members of alpha-actinin family play pivotal roles in cell proliferation, migration, and invasion, the interaction between alpha-actinin-2 and angiogenin may underline one possible mechanism of angiogenin in angiogenesis. Our finding presents the first evidence of an interaction of a cytosolic protein with angiogenin, which might be a novel interference target for anti-angiogenesis and anti-tumor therapy.