We describe that galectin-1 (gal-1) is a receptor for the angiogenesis inhibitor anginex, and that the protein is crucial for tumor angiogenesis. gal-1 is overexpressed in endothelial cells of different human tumors. Expression knockdown in cultured endothelial cells inhibits cell proliferation and migration. The importance of gal-1 in angiogenesis is illustrated in the zebrafish model, where expression knockdown results in impaired vascular guidance and growth of dysfunctional vessels. The role of gal-1 in tumor angiogenesis is demonstrated in gal-1-null mice, in which tumor growth is markedly impaired because of insufficient tumor angiogenesis. Furthermore, tumor growth in gal-1-null mice no longer responds to antiangiogenesis treatment by anginex. Thus, gal-1 regulates tumor angiogenesis and is a target for angiostatic cancer therapy.angiostatic therapy ͉ endothelial cell ͉ galectin ͉ tumor models ͉ anginex A n adequate vasculature is a prerequisite for tumors to grow, and the need for neovessel formation (or angiogenesis) provides a target for treatment of cancer (1). Endothelial cells (EC) that line the tumor vasculature are particularly suitable target cells for therapeutic approaches, because they are easily accessible to agents delivered by the blood (2). However, to affect only tumor vasculature, specific targets on angiogenically active EC are essential. To date, only a few targets of tumor vasculature have been identified (3).We recently developed the specific angiostatic peptide anginex, which inhibits tumor growth through specific inhibition of angiogenesis (4-6). Although a broad profile of activities of anginex is known, such as prevention of EC adhesion and induction of apoptosis, the molecular target on tumor EC was never identified. In a receptor-finding study using a yeast twohybrid screening approach, we identified galectin-1 (gal-1) as a target protein of anginex.gal-1 belongs to a family of carbohydrate-binding proteins that share a conserved carbohydrate recognition domain of Ϸ130 aa (7-9). Over a dozen mammalian galectins have been described (10, 11), and members of this family are expressed in a wide range of species, suggesting an important role for galectins in basic cellular mechanisms. Galectins can be secreted and, depending on the cell type or state of differentiation, they have been found in the nucleus, cytoplasm, or extracellular matrix. It has been proposed that gal-1 mediates cell adhesion and migration (12) and is involved in several processes, including proliferation (13), apoptosis (14), and even mRNA splicing (15). The role of gal-1 in EC function or vascular biology has not been extensively studied.Here, we describe the function of gal-1 in angiogenesis. We provide direct functional evidence that gal-1 is required for tumor angiogenesis and outgrowth of tumors. Furthermore, we show that gal-1 is the target for the potent angiogenesis inhibitor anginex, thus establishing gal-1 as an important target for anticancer therapy.Results gal-1 Binds the Angiostatic Peptide Anginex...

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Tumor angiogenesis is a key event in cancer progression. Here, we report that tumors can stimulate tumor angiogenesis by secretion of galectin-1. Tumor growth and tumor angiogenesis of different tumor models are hampered in galectin-1-null (gal-1 −/− ) mice. However, tumor angiogenesis is less affected when tumor cells express and secrete high levels of galectin-1. Furthermore, tumor endothelial cells in gal-1 −/− mice take up galectin-1 that is secreted by tumor cells. Uptake of galectin-1 by cultured endothelial cells specifically promotes H-Ras signaling to the Raf/mitogen-activated protein kinase/extracellular signal-regulated kinase (Erk) kinase (Mek)/Erk cascade and stimulates endothelial cell proliferation and migration. Moreover, the activation can be blocked by galectin-1 inhibition as evidenced by hampered membrane translocation of H-Ras.GTP and impaired Raf/Mek/Erk phosphorylation after treatment with the galectin-1-targeting angiogenesis inhibitor anginex. Altogether, these data identify galectin-1 as a proangiogenic factor. These findings have direct implications for current efforts on galectin-1-targeted cancer therapies. Cancer Res; 70(15); 6216-24. ©2010 AACR.

Tumor escape from immunity, as well as the failure of several anti-cancer vaccination and cellular immunotherapy approaches, is suggested to be due to the angiogenesis-mediated suppression of endothelial cell (EC) adhesion molecules involved in leukocyte-vessel wall interactions. We hypothesized that inhibition of angiogenesis would overcome this escape from immunity. We investigated this in vivo by means of intravital microscopy and ex vivo by immunohistochemistry in two mouse tumor models. Angiogenesis inhibitors anginex, endostatin, and angiostatin, and the chemotherapeutic agent paclitaxel were found to significantly stimulate leukocyte-vessel wall interactions by circumvention of EC anergy in vivo, i.e., by the up-regulation of endothelial adhesion molecules in tumor vessels. This was confirmed by in vitro studies of cultured EC at the protein and mRNA levels. The new angiostatic designer peptide anginex was most potent at overcoming EC anergy; the enhanced leukocyte-vessel interactions led to an increase in the numbers of tumor infiltrating leukocytes. While anginex inhibited tumor growth and microvessel density significantly, the amount of infiltrated leukocytes (CD45), as well as the number of CD8+ cytotoxic T lymphocytes, was enhanced markedly. The current results suggest that immunotherapy strategies can be improved by combination with anti-angiogenesis.

It is known that angiogenesis is of pivotal importance for the development of endometriosis. However, in the treatment of endometriosis patients, prevention of endometriosis lesion development only will not be sufficient as a therapy. Treatment options, aimed at interfering with established lesions, have to be developed. In this study we evaluated whether inhibition of angiogenesis by angiostatic therapy is also effective in antagonizing the sustentation of endometriosis. We evaluated the effect of the angiostatic compounds antihuman vascular endothelial growth factor, TNP-470, endostatin, and anginex on the growth of established endometriosis lesions in the nude mouse model. We show that human endometrium in the proliferative endometrium is highly angiogenic and that vascular endothelial growth factor-A is the most important angiogenesis promotory factor. The angiostatic compounds significantly decreased microvessel densities and the number of established endometriosis lesions. In the remaining lesions, the number of pericyte-protected vessels is not different in control and treated mice; however, the number of unprotected vessels was significantly reduced in the groups treated with the angiostatic agents. Our data demonstrate that inhibitors of angiogenesis effectively interfere with the maintenance and growth of endometriosis by inhibiting angiogenesis. This suggests that the use of angiostatic agents may be promising as a therapy for endometriosis.

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Antibody detection is of fundamental importance in many diagnostic and bioanalytical assays, yet current detection techniques tend to be laborious and/or expensive. We present a new sensor platform (LUMABS) based on bioluminescence resonance energy transfer (BRET) that allows detection of antibodies directly in solution using a smartphone as the sole piece of equipment. LUMABS are single-protein sensors that consist of the blue-light emitting luciferase NanoLuc connected via a semiflexible linker to the green fluorescent acceptor protein mNeonGreen, which are kept close together using helper domains. Binding of an antibody to epitope sequences flanking the linker disrupts the interaction between the helper domains, resulting in a large decrease in BRET efficiency. The resulting change in color of the emitted light from green-blue to blue can be detected directly in blood plasma, even at picomolar concentrations of antibody. Moreover, the modular architecture of LUMABS allows changing of target specificity by simple exchange of epitope sequences, as demonstrated here for antibodies against HIV1-p17, hemagglutinin (HA), and dengue virus type I. The combination of sensitive ratiometric bioluminescent detection and the intrinsic modularity of the LUMABS design provides an attractive generic platform for point-of-care antibody detection that avoids the complex liquid handling steps associated with conventional immunoassays.

Nanoparticle applications in medicine have seen a tremendous growth in the last decade. In addition to their drug targeting application and their ability to improve bioavailability of drugs, nanoparticles can be designed to allow their detection with a variety of imaging methodologies. In the current study we developed a multimodal nanoparticle platform to enable imaging guided therapy, which was evaluated in a colon cancer mouse model. This “theranostic” platform, is based on oil-in-water nanoemulsions and carries iron oxide nanocrystals for MRI, the fluorescent dye Cy7 for NIRF imaging and the hydrophobic glucocorticoid prednisolone acetate valerate (PAV) for therapeutic purposes. Angiogenesis targeted nanoemulsions functionalized with αvβ3-specific RGD-peptides were evaluated as well. When subcutaneous tumor were palpable the nanoemulsions were administered at a dose of 30 mg FeO/kg and 10 mg PAV/kg. MRI and NIRF imaging showed significant nanoparticle accumulation in the tumors, while tumor growth profiles revealed a potent inhibitory effect in all the PAV-nanoemulsions treated animals as compared to the ones treated with control nanoemulsions, the free drug or saline. In conclusion, this study demonstrated that our nanoemulsions, when loaded with PAV, iron oxide nanocrystals and Cy7, represent a flexible and unique theranostic nanoparticle platform that can be applied for imaging guided therapy of cancer.