Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0017638 (glioma)
 30,880 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Tumor microvessels differ in structure and metabolic function from normal vasculature, and neoangiogenesis is associated with quantitative and qualitative changes in expression of endothelial proteins. Such molecules could serve as molecular addresses differentiating the tumor vasculature from those of the normal brain. We have applied Systematic Evolution of Ligands by EXponential enrichment (SELEX) against transformed endothelial cells as a complex target to select single-stranded DNA-ligands (aptamers) that function as histological markers to detect microvessels of rat experimental glioma, a fatal brain tumor that is highly vascularized. Both the SELEX selection procedure as well as subsequent deconvolution-SELEX were analyzed by fluorescence based methods (flow cytometry and fluorescence microscopy). Of 25 aptamers analyzed, one aptamer was selected that selectively bound microvessels of rat brain glioblastoma but not the vasculature of the normal rat brain including peritumoral areas. The molecular target protein of aptamer III.1 was isolated from endothelial cells by ligand-mediated magnetic DNA affinity purification. This protein was identified by mass spectrometry as rat homologue of mouse pigpen, a not widely known endothelial protein the expression of which parallels the transition from quiescent to angiogenic phenotypes in vitro. Because neoangiogenesis, the formation of new blood vessels, is a key feature of tumor development, the presented aptamer can be used as a probe to analyze pathological angiogenesis of glioblastoma. The presented data show that pigpen is highly expressed in tumor microvessels of experimental rat brain glioblastoma and may play an important role in warranting blood supply, thus growth of brain tumors.
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PMID:Systematic evolution of a DNA aptamer binding to rat brain tumor microvessels. selective targeting of endothelial regulatory protein pigpen. 1127 54

Scatter factor/hepatocyte growth factor (SF/HGF) is a pleiotropic cytokine that has been implicated in glioma invasion and angiogenesis. The SF/HGF receptor, MET, has been found to be expressed in neoplastic astrocytes as well as in endothelial cells of the tumor vasculature. Both SF/HGF and MET expression have also been described to correlate with the malignancy grade of human gliomas. However, most glioblastoma cell lines lack SF/HGF expression, raising the question of the cellular origin of SF/HGF in vivo. Using in situ hybridization, we analyzed glioblastomas, anaplastic astrocytomas, diffuse astrocytomas, pilocytic astrocytomas, and normal brain for the expression of SF/HGF mRNA. We detected strong SF/HGF expression by the majority of the tumor cells and by vascular endothelial cells in all glioblastoma specimens analyzed. Combined use of in situ hybridization with fluorescence immunohistochemistry confirmed the astrocytic origin of the SF/HGF-expressiong cells. In contrast, CD68-immunoreactive microglia/macrophages, as well as vascular smooth muscle cells reactive to alpha-smooth muscle actin, lacked SF/HGF expression. In anaplastic, diffuse, and pilocytic astrocytomas, SF/HGF expression was confined to a subset of tumor cells, and signals were less intense than in glioblastomas. In addition, we detected SF/HGF mRNA in cortical neurons. SF/HGF expression was not up regulated around necroses or at tumor margins. MET immunoreactivity was observed in GFAP-expressing astrocytic tumor cells and endothelial cells as well as in a subset of microglia/macrophages. We conclude that in vivo, both autocrine and paracrine stimulation of tumor cells and endothelium through the SF/HGF-MET system are likely to contribute to tumor invasion and angiogenesis. Lack of SF/HGF expression by most cultured glioblastoma cells is not representative of the in vivo situation and most likely represents a culture artifact.
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PMID:Expression and localization of scatter factor/hepatocyte growth factor in human astrocytomas. 1129 84

The gene for the major angiogenic factor, vascular endothelial growth factor (VEGF), encodes several spliced isoforms. We reported previously that overexpression of two VEGF isoforms, VEGF(121) and VEGF(165), by human glioma U87 MG cells induced tumor-associated intracerebral hemorrhage, whereas expression of a third form, VEGF(189), did not cause vessel rupture. Here, we test whether these VEGF isoforms have distinct activities for enhancing vascularization and growth of gliomas in mice. U87 MG cells that overexpressed VEGF(165) or VEGF(189) grew more rapidly than the parental cells in both s.c. and intracranial (i.c.) locations. However, cells that overexpressed VEGF(121) only showed enhancement of i.c. tumor growth but had a minimal effect on s.c. glioma progression. At both anatomical sties, VEGF(165) and VEGF(189) strongly augmented neovascularization, whereas VEGF(121) only increased vessel density in brain tumors. In each type of glioma, expression of VEGF receptors -1 and -2 largely phenocopied the tumor vasculature, because increased VEGF/VEGF receptor-activated microvessel densities were strongly correlated with the angiogenicity and tumorigenicity elicited by the VEGF isoforms at both anatomical sites. One notable difference between the sites was the expression of vitronectin, a prototypic ligand of alpha(v)beta(3) and alpha(v)beta(5) integrins, detected in i.c. but not in s.c., gliomas. Endothelial cell migration stimulated by VEGF(121) was potentiated by vitronectin to a greater extent than that stimulated by VEGF(165). This data demonstrates that VEGF isoforms have distinct activities at different anatomical sites and suggest that the microenvironment of different tissues affects the function of VEGF isoforms.
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PMID:Vascular endothelial growth factor isoforms display distinct activities in promoting tumor angiogenesis at different anatomic sites. 1173 44

Photodynamic therapy (PDT), locally applied to solid C6 rat glioma tumors in the foot of CD1 nude mice, eradicated the primary tumor and also decreased the rate of groin and lung metastases. Pd-Bacteriopheophorbide (Pd-Bpheid), a novel photosensitizer synthesized in our laboratory, was used in our study. The primary lesion in the hind leg was treated by an i.v. injection of 5 mg/kg of Pd-Bpheid and immediate illumination (650-800 nm, 360 J/cm(2)). This protocol and the surgical amputation of the leg were compared for local and metastasis responses. Following PDT, hemorrhage, inflammation with tumor necrosis and flattening were observed and histologically verified in the photodynamically treated tumor. Whereas local tumor control rates were up to 64% following PDT, in surgically treated animals, local tumor control was absolute. The rates of metastases in the groin and the lungs were at least 12-fold lower in the photodynamically treated animals compared with untreated or surgery-treated groups. The overall cure rates after PDT or surgery were 36% and 6%, respectively, at 8 weeks. These findings suggest that local PDT with Pd-Bpheid, which acts primarily on the tumor vasculature, efficiently eradicates the solid C6 tumors. In addition, the local PDT of the primary lesion has beneficial therapeutic effects on remote C6 metastasis, which is not obtained with surgery. It is therefore suggested, that although surgery is highly efficient for the immediate removal of the primary tumor, it lacks such systemic, therapeutic effects on distant metastases. Pd-Bpheid-PDT may thus offer a potentially superior curative therapy for C6 glioma tumors in the limb by eradicating the target tumor and by reducing the rate of metastasis in the groin and lung, possibly due to innate immunity.
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PMID:Local photodynamic therapy (PDT) of rat C6 glioma xenografts with Pd-bacteriopheophorbide leads to decreased metastases and increase of animal cure compared with surgery. 1197 45

Diagnosis and therapy for malignant gliomas represents one of the most challenging problems in clinical oncology. Current treatment of malignant glioma is multimodal, involving surgical resection, radiotherapy and chemotherapy. Even with these combined therapies, patients usually die within 1 to 2 years after onset of symptoms. Clearly, improved strategies for selective delivery of therapeutic agents to gliomas are needed to combat these devastating and usually fatal cancers. This review summarizes current knowledge concerning targetable molecular markers on the surface of glial tumor cells and tumor vasculature. Such markers are altered or up-regulated in gliomas compared to normal tissues, or they might be glioma-restricted. These markers include growth factor receptors, cell-surface adhesion molecules, and membrane-type matrix metalloproteinases. Current approaches that utilize growth factor peptides and peptide/antibodies identified via phage display technology as carrier ligands for targeting malignant gliomas are discussed.
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PMID:Molecular markers of glial tumors: current targeting strategies. 1267 86

The systemic administration of endogenous inhibitors significantly reduced the growth of human glioma in vivo, but required the production of a large amount of biologically active protein. In this study we reduced the amount of protein needed and optimized the therapeutical response by delivering the endogenous inhibitors locally into the brain by osmotic minipumps. Human hemopexin fragment of MMP-2 or COOH-terminal fragment of platelet factor-4 were delivered locally and continuously into the brain of mice implanted intracranially with glioma cells, by osmotic minipumps connected to an intracranial catheter. Local delivery of human hemopexin fragment of MMP-2 and COOH-terminal fragment of platelet factor-4 significantly inhibited the growth of well-established malignant glioma in nude and BALB/C mice. When the inhibitors were given at the same concentration, the efficacy of the local delivery was much higher than that reached with the systemic administration, both when the inhibitor was administered daily or continuously by s.c. minipumps. Moreover, the local delivery reduced the amount of protein needed to reach a significant therapeutic response. Intracerebral delivery maintained a long-term control of glioma growth and inhibited glioma recurrence in a surgical resection model. Treatment showed no side effects. Histochemical analysis of tumors showed that the tumor growth inhibition was the result of a decrease in tumor vasculature and a change in tumor vessel morphology. Our data demonstrate that local intracerebral delivery of endogenous inhibitors effectively inhibits malignant glioma growth and reduces the amount of protein needed to reach a therapeutical response.
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PMID:Local intracerebral delivery of endogenous inhibitors by osmotic minipumps effectively suppresses glioma growth in vivo. 1275 Feb 72

Despite aggressive surgery and post-operative radiation and chemotherapy, the prognosis is poor for glioblastoma patients. Anti-angiogenic therapy with compounds such as endostatin could delay the onset of relapse. However, the short systemic half-life of this proteins as well as the blood-brain barrier makes the use of this therapy difficult for brain cancer patients. The aim of this project is to develop and implant genetically engineered producer cells secreting endostatin that are encapsulated in calcium cross-linked alginate gel beads. Encapsulation of cells within alginate gels has a potential as a sustained release system in addition to the fact that the encapsulation technology protects the cells from rejection by the immune system. Human embryonal kidney 293 cells have been transfected with the gene for endostatin. These cells have been encapsulated in calcium cross-linked alginate gels and optimized for the secretion of endostatin. Alginate gel beads implanted into rat brain have shown only a moderate loss in cell viability but extended endostatin release for periods of up to 12 months. Visualization of the anti-angiogenic effect on C6 rat glioma growth, tumor vasculature and microhemodynamics has been demonstrated by using intravital video microscopy. The data indicates that endostatin greatly affects tumor-associated microcirculation but does not appear to affect normal microcirculation. The local delivery of endostatin seems to specifically affect tumor-associated microvessels by reduction of the vessel density, diameter and functionality. Tumor cell migration and invasion was greatly reduced in the endostatin treated animals.
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PMID:Cell therapy using encapsulated cells producing endostatin. 1453 71

Until recently, it was generally accepted that the vascularization of solid tumors occurred exclusively through the sprouting and co-option from pre-existing blood vessels. Growing evidence now suggests that bone marrow-derived endothelial progenitor cells (EP) circulate in the blood and may play an important role in the formation of new blood vessels in certain tumors. Whether endothelial progenitors participate in the vascularization of brain tumors has not yet been evaluated. In this study, we examined the contribution of EP to tumor angiogenesis in a murine glioma tumor model. Donor bone marrow cells obtained from transgenic mice constitutively expressing beta-galactosidase or GFP either ubiquitously or transcriptionally regulated by an endothelial specific promotor Tie-2 were injected into lethally irradiated adult mice. After bone marrow reconstitution by donor cells, mice were implanted with syngeneic GL261 murine glioma cells. Morphological and confocal 3-dimensional analysis showed that the majority of the engrafted donor marrow cells were expressing hematopoietic and/or microglia markers, but did not appreciably contribute to the tumor vasculature. Implantation of glioma cells genetically engineered to overexpress VEGF produced highly vascularized tumors. However, the number of endothelial progenitors incorporated in the tumor vasculature did not increase. These data strongly suggest that neovascularization in the brain might fundamentally be regulated by the sprouting of pre-existing vessels and implicate that circulating endothelial progenitors do not play a significant role in this process.
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PMID:Minor contribution of bone marrow-derived endothelial progenitors to the vascularization of murine gliomas. 1465 62

Multidisciplinary treatment strategies for patients with malignant brain tumors have resulted in only small gains in terms of prognosis in spite of the use of aggressive therapy. There is a growing realization that a paradigm shift is needed in the conceptual approaches to glioma therapy. Such approaches will rely on identification and modification of key cellular targets that define the biological behavior of these tumors. Among the targets for such treatment approaches, tumor angiogenesis has captured the attention of not only the medical field but also of the lay public because of its conceptual departure from traditional methods of cancer therapy. Angiogenesis and vascular proliferation are particularly important in the growth and progression of malignant gliomas and are used as indicators of the degree of malignancy. Recent studies have helped us gain a better understanding of the molecular mediators of this process. It is now evident that after the initial formation of malignancy the continued growth of a glioma is critically dependent on its angiogenic potential. Hence, several approaches to control angiogenesis are being developed and tested. Preliminary results from clinical studies have shown that angiogenesis inhibition is a valid approach as a therapeutic strategy against gliomas but it is also becoming evident that inhibition of individual modulators of this process may not yield the expected impact on prognosis. To fully realize the potential of antiangiogenic therapy, a deeper understanding of the interplay between the tumor vasculature and its environment is needed. Angiogenesis inhibitors have made the transition from preclinical studies to the clinical arena; it remains for ongoing human trials of such agents to fully explore the feasibility and efficacy of these agents in order to exploit the potential of this approach.
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PMID:Inhibition of angiogenesis as a therapeutic strategy against brain tumors. 1501 67

Bone marrow-derived endothelial precursor cells incorporate into neovasculature and have been successfully used as vehicles for gene delivery to brain tumors. To determine whether systemically administered Sca1+ bone marrow cells labeled with superparamagnetic iron oxide nanoparticles can be detected by in vivo magnetic resonance imaging in a mouse brain tumor model, mouse Sca1+ cells were labeled in vitro with ferumoxides-poly-L-lysine complexes. Labeled or control cells were administered intravenously to glioma-bearing severe combined immunodeficient (SCID) mice. Magnetic resonance imaging (MRI) was performed during tumor growth. Mice that received labeled cells demonstrated hypointense regions within the tumor that evolved over time and developed a continuous dark hypointense ring at a consistent time point. This effect was not cleared by administration of a gadolinium contrast agent. Histology showed iron-labeled cells around the tumor rim in labeled mice, which expressed CD31 and von Willebrand factor, indicating the transplanted cells detected in the tumor have differentiated into endothelial-like cells. These results demonstrate that MRI can detect the incorporation of magnetically labeled bone marrow-derived precursor cells into tumor vasculature as part of ongoing angiogenesis and neovascularization. This technique can be used to directly identify neovasculature in vivo and to facilitate gene therapy by noninvasively monitoring these cells as gene delivery vectors.
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PMID:Noninvasive MR imaging of magnetically labeled stem cells to directly identify neovasculature in a glioma model. 1533 44


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