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)

Celastrol, a compound purified from Tripterygium wilfordii whose preparations have been used for clinical treatment for rheumatoid arthritis, has been demonstrated to have antiangiogenic activity, and be inhibitory against mice tumor growth by a few recent studies. However, whether its antiangiogenic activity plays a role in the celastrol-mediated suppression of tumor growth and the molecular basis of anti-tumor activity are poorly understood. In this study, we found that celastrol inhibited the growth of human glioma xenografts in mice, which concurred with the suppression of angiogenesis. Interestingly, while celastrol had no effect on either the expression of VEGF or its mRNA levels, celastrol treatment lowered the expression levels of its receptors (VEGFR-1 and VEGFR-2) and their mRNA levels. These findings suggest that celastrol have potential to be used as an antiangiogenesis drug through its role in suppressing VEGF receptors expression that might consequently reduce the signal transduction between VEGF and VEGFR.
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PMID:Celastrol inhibits the growth of human glioma xenografts in nude mice through suppressing VEGFR expression. 1834 27

Glioblastomas are heterogeneous tumors displaying regions of necrosis, proliferation, angiogenesis, apoptosis and invasion. SPARC, a matricellular protein that negatively regulates angiogenesis and cell proliferation, but enhances cell deadhesion from matrix, is upregulated in gliomas (Grades II-IV). We previously demonstrated that SPARC promotes invasion while concomitantly decreasing tumor growth, in part by decreasing proliferation of the tumor cells. In other cancer types, SPARC has been shown to influence tumor growth by altering matrix production, and by decreasing angiogenesis via interfering with the VEGF-VEGFR1 signaling pathway. We therefore examined whether the SPARC-induced decrease in glioma tumor growth was also, in part, due to alterations in matrix and/or decreased vascularity, and assessed SPARC-VEGF interactions. The data demonstrate that SPARC upregulates glioma matrix, collagen I is a constituent of the matrix and SPARC promotes collagen fibrillogenesis. Furthermore, SPARC suppressed glioma vascularity, and this was accompanied by decreased VEGF expression and secretion, which was, in part, due to reduced VEGF165 transcript abundance. These data indicate that SPARC modulates glioma growth by altering the tumor microenvironment and by suppressing tumor vascularity through suppression of VEGF expression and secretion. These experiments implicate a novel mechanism, whereby SPARC regulates VEGF function by limiting the available growth factor. Because SPARC is considered to be a therapeutic target for gliomas, a further understanding of its complex signaling mechanisms is important, as targeting SPARC to decrease invasion could undesirably lead to the growth of more vascular and proliferative tumors.
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PMID:SPARC-induced increase in glioma matrix and decrease in vascularity are associated with reduced VEGF expression and secretion. 1835 May 69

Aggressive human brain tumours (gliomas) often express a truncated and oncogenic form of the epidermal growth factor receptor, known as EGFRvIII. Within each tumour only a small percentage of glioma cells may actually express EGFRvIII; however, most of the cells exhibit a transformed phenotype. Here we show that EGFRvIII can be 'shared' between glioma cells by intercellular transfer of membrane-derived microvesicles ('oncosomes'). EGFRvIII expression in indolent glioma cells stimulates formation of lipid-raft related microvesicles containing EGFRvIII. Microvesicles containing this receptor are then released to cellular surroundings and blood of tumour-bearing mice, and can merge with the plasma membranes of cancer cells lacking EGFRvIII. This event leads to the transfer of oncogenic activity, including activation of transforming signalling pathways (MAPK and Akt), changes in expression of EGFRvIII-regulated genes (VEGF, Bcl-x(L), p27), morphological transformation and increase in anchorage-independent growth capacity. Thus, membrane microvesicles of cancer cells can contribute to a horizontal propagation of oncogenes and their associated transforming phenotype among subsets of cancer cells.
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PMID:Intercellular transfer of the oncogenic receptor EGFRvIII by microvesicles derived from tumour cells. 1842 14

Human gliomas, including astrocytomas, consist of highly heterogeneous populations of cells that represent different stages of malignancy. Glioblastoma multiforme is the most highly vascularised class of solid tumour. In order to develop efficacious adjuvant therapies for gliomas the growth pathway(s) targeted must be common to all of these tumours. As angiogenesis is a requirement for all solid tumour growth, we have targeted this process in order to suppress glioma growth in vivo. We have applied antisense VEGF gene expression to disrupt the VEGF/VEGF receptor paracrine pathway in C6 glioma cells and, thereby, inhibit tumour angiogenesis. C6 glioma cells which constitutively express antisense VEGF sequences were demonstrated to have significantly inhibited growth rates when implanted intracranially. Antisense VEGF expressing tumours had a markedly lower level of vascularisation which was accompanied by an increased level of necrosis compared to control tumours. Furthermore, these data support the notion that VEGF is the sole factor required for tumour angiogenesis as other potentially angiogenic factors could not compensate for the reduced level of VEGF expression in the antisense-VEGF expressing tumours. Our findings also suggest that the inhibition of angiogenesis is sufficient to significantly suppress tumour growth and is thus an effective point for therapeutic intervention for gliomas and all solid tumours.
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PMID:The expression of antisense vascular endothelial growth factor (VEGF) sequences inhibits intracranial C6 glioma growth in vivo by suppressing tumour angiogenesis. 1863 4

The recombinant kringle domain (UK1) of urokinase-type plasminogen activator (uPA) has been shown to possess anti-angiogenic activity in vitro and in vivo. It has also been found to inhibit in vivo malignant glioma growth. In contrast, direct interaction of the kringle domain of uPA and integrin alphavbeta3 has been reported to be involved in plasminogen and leukocyte activation by uPA. Since integrin alphavbeta3 is involved in tumor angiogenesis, we investigated whether integrin alphavbeta3 is involved in the inhibitory function of UK1 in angiogenesis, by examining its anti-migratory activity. In a modified Boyden chamber assay, the Pichia-expressed UK1 dose-dependently inhibited the VEGF-induced migration of human umbilical vein endothelial cells (HUVECs). However, in the absence of growth factor stimulation, soluble UK1 alone did not induce or inhibit HUVEC migration. In cell adhesion, immobilized UK1 promoted HUVEC adhesion and spreading which were compared to BSA. Pretreatment of the anti-alphavbeta3 integrin antibody, significantly inhibited HUVEC binding to immobilized UK1, whereas neither anti-alpha2beta1 nor anti-alpha5beta1 integrin antibody had any effect, although pre-treatment of the soluble UK1 showed no marked alteration of the binding level of anti-alphavbeta3 antibody to HUVECs in FACS analysis. In a modified Boyden chamber assay, the function blocking antibodies against integrins alphavbeta3, alpha2beta1 and alpha5beta1 did not completely prevent the inhibitory effect of UK1 in HUVEC migration. These results suggest that UK1 interacts with integrin alphavbeta3, but its anti-migratory activity on endothelial cells is not significantly mediated by integrin alphavbeta3.
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PMID:Integrin alphavbeta3 is not significantly implicated in the anti-migratory effect of anti-angiogenic urokinase kringle domain. 1869 16

Gliomas are characterised by local infiltration, migration of tumour cells across long distances and sustained angiogenesis; therefore, proteins involved in these processes are most likely important. Such candidates are semaphorins involved in axon guidance and cell migration. In addition, semaphorins regulate tumour progression and angiogenesis. For cell signalling, class-4 semaphorins bind directly to plexins, whereas class-3 semaphorins require additional neuropilin (NRP) receptors that also bind VEGF(165). The anti-angiogenic activity of class-3 semaphorins can be explained by competition with VEGF(165) for NRP binding. In this study, we analysed the expressions of seven semaphorins of class-3, SEMA4D, VEGF and the NRP1 and NRP2 receptors in 38 adult glial tumours. In these tumours, SEMA3B, SEMA3G and NRP2 expressions were related to prolonged survival. In addition, SEMA3D expression was reduced in high-grade as compared with low-grade gliomas. In contrast, VEGF correlated with higher grade and poor survival. Thus, our data suggest a function for a subset of class-3 semaphorins as inhibitors of tumour progression, and the prognostic value of the VEGF/SEMA3 balance in adult gliomas. Moreover, in multivariate analysis, SEMA3G was found to be the only significant prognostic marker.
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PMID:Semaphorin, neuropilin and VEGF expression in glial tumours: SEMA3G, a prognostic marker? 1878 Nov 79

CCN proteins are key regulators of signaling pathways that are essential for the control of normal life, from birth to death. As such, they make use of their unique mosaic structure to interact with several other regulatory proteins and ligands that control the fate of living cells. The various functions attributed to the CCN proteins may sometimes appear contradictory, but this situation reflects the complexity of the multimolecular scaffolds in which CCN proteins are engaged and the critical impact of the microenvironment that dictates the bioavailability of the elementary building blocks. CCN3 is one of the best examples of a CCN protein showing biological properties which may at first glance appear opposite or contradictory. Indeed, CCN3 acts both as a tumor suppressor and is associated with higher metastatic potential. Furthermore, the physical interaction of CCN3 with VEGF and its potential antiangionenic activity in glioma cells are in apparent contradiction with its proangiogenic activity in rabbit cornea. In this communication, I am revisiting the observations that led us to these apparent contradictions. After pointing out how the methodologies that were employed might have contributed to the confusion, I briefly discuss the dual biological activities of CCN3 in the context of tumor cell engineering and survival prognosis.
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PMID:CCN3: Doctor Jekyll and Mister Hyde. 1878 88

Glioblastoma multiforme (GBM) is one of the most highly vascularized of all human tumors. Our objective was to characterize a 3-dimensional (3-D) in vitro angiogenesis model by co-culturing HUVEC and GBM cells, and to study the role of VEGF in mediating capillary tubule formation in this model. HUVEC-coated dextran beads were suspended in fibrin gel with human glioma cells on top. The number of sprouts and the length of the processes were measured. HUVEC can be induced to form sprouts and longer processes with lumens, in co-culture with glioma cells that secrete VEGF. Addition of exogenous VEGF enhances this effect. In the absence of glioma cells, many single HUVEC migrate away from the beads, without significant tubule formation. Hypoxia further stimulated sprout formation by 50-100%. Anti-VEGF neutralizing antibody suppressed HUVEC sprouting by 75% in co-culture with glioma cells. This 3-D in vitro co-culture system provides a robust and useful model for analysis of the major steps of glioma-induced angiogenesis.
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PMID:In vitro angiogenesis by human umbilical vein endothelial cells (HUVEC) induced by three-dimensional co-culture with glioblastoma cells. 1903 23

SU5416 is a novel small molecule tyrosine kinase inhibitor of the VEGF receptors 1 and 2. A phase I dose escalation study stratified by concurrent use (stratum II) or absence (stratum I) of enzyme-inducing anticonvulsant drugs was undertaken to estimate the maximum-tolerated dose (MTD) and to describe the toxicity profile of SU5416 in pediatric patients with refractory brain tumors. Dose escalations were conducted independently for stratum I starting at 110 mg/m(2) while stratum II started at 48 mg/m(2). Thirty-three eligible patients were treated on stratum I (n = 23) and stratum II (n = 10). Tumor types included 23 glial tumors, 4 neural tumors, 4 ependymomas, and 2 choroid plexus carcinomas. The MTD in stratum I was initially estimated to be 110 mg/m(2). The protocol was amended to determine the MTD after excluding transient AST elevation. Re-estimation of the MTD began at the 145 mg/m(2) dose level but due to development of SU5416 being stopped by the sponsor, the trial was closed before completion. The most serious drug-related toxicities were grade 3 liver enzyme abnormalities, arthralgia, and hallucinations. The plasma pharmacokinetics of SU5416 was not significantly affected by the concurrent administration of enzyme-inducing anticonvulsant drugs. Mean values of the total body clearance, apparent volume of distribution, and terminal phase half-life of SU5416 for the 19 patients in stratum I were 26.1 +/- 12.5 l/hr/m(2), 41.9 +/- 21.4 l/m(2), and 1.11 +/- 0.41 hr, respectively. The plasma pharmacokinetics of SU5416 in children was similar to previously reported findings in adult cancer patients. Prolonged disease stabilization was observed in 4 of 16 stratum I patients.
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PMID:Phase I study of SU5416, a small molecule inhibitor of the vascular endothelial growth factor receptor (VEGFR) in refractory pediatric central nervous system tumors. 1906 67

Hypoxia is a critical aspect of the microenvironment in glioma and generally signifies unfavorable clinical outcome. Effective targeting of hypoxic areas in gliomas remains a significant therapeutic challenge. New therapeutic platforms using neural stem cells (NSC) for tumor-targeted drug delivery show promise in treatment of cancers that are refractory to traditional therapies. However, the molecular mechanisms of NSC targeting to hypoxic tumor areas are not well understood. Therefore, we investigated the role of hypoxia in directed migration of NSCs to glioma and identified the specific signaling molecules involved. Our data showed that hypoxia caused increased migration of human HB1.F3 NSCs to U251 human glioma-conditioned medium in vitro. In HB1.F3 NSCs, hypoxia led to up-regulation of CXCR4, urokinase-type plasminogen activator receptor (uPAR), vascular endothelial growth factor receptor 2 (VEGFR2), and c-Met receptors. Function-inhibiting antibodies to these receptors inhibited the migration of HB1.F3 cells to glioma-conditioned medium. Small interfering RNA knockdown of hypoxia-inducible factor-1alpha in glioma cells blocked the hypoxia-induced migration of NSCs, which was due to decreased expression of stromal cell-derived factor-1 (SDF-1), uPA, and VEGF in glioma cells. Our in vivo data provided direct evidence that NSCs preferentially distributed to hypoxic areas inside intracranial glioma xenografts, as detected by pimonidazole hypoxia probe, as well as to the tumor edge, and that both areas displayed high SDF-1 expression. These observations indicate that hypoxia is a key factor in determining NSC tropism to glioma and that SDF-1/CXCR4, uPA/uPAR, VEGF/VEGFR2, and hepatocyte growth factor/c-Met signaling pathways mediate increased NSC-to-glioma tropism under hypoxia. These results have significant implications for development of stem cell-mediated tumor-selective gene therapies.
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PMID:Neural stem cell tropism to glioma: critical role of tumor hypoxia. 1907 27


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