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Tumor cells with stem cell-like properties can be cultured from human glioblastomas by using conditions that select for the expansion of neural stem cells. We generated cell lines from glioblastoma specimens with the goal to obtain model systems for glioma stem cell biology. Unsupervised analysis of the expression profiles of nine cell lines established under neural stem cell conditions yielded two distinct clusters. Four cell lines were characterized by the expression of neurodevelopmental genes. They showed a multipotent differentiation profile along neuronal, astroglial and oligodendroglial lineages, grew spherically in vitro, expressed CD133 and formed highly invasive tumors in vivo. The other five cell lines shared expression signatures enriched for extracellular matrix-related genes, had a more restricted differentiation capacity, contained no or fewer CD133+ cells, grew semiadherent or adherent in vitro and displayed reduced tumorigenicity and invasion in vivo. Our findings show that stable, multipotent glioblastoma cell lines with a full stem-like phenotype express neurodevelopmental genes as a distinctive feature, which may offer therapeutic targeting opportunities. The generation of another distinct cluster of cell lines showing similarly homogeneous profiling but restricted stem cell properties suggests that different phenotypes exist, each of which may lead to the typical appearance of glioblastoma.

The neural stem cell marker CD133 is reported to identify cells within glioblastoma (GBM) that can initiate neurosphere growth and tumor formation; however, instances of CD133(-) cells exhibiting similar properties have also been reported. Here, we show that some PTEN-deficient GBM tumors produce a series of CD133(+) and CD133(-) self-renewing tumor-initiating cell types and provide evidence that these cell types constitute a lineage hierarchy. Our results show that the capacities for self-renewal and tumor initiation in GBM need not be restricted to a uniform population of stemlike cells, but can be shared by a lineage of self-renewing cell types expressing a range of markers of forebrain lineage.

Purpose Mutation in isocitrate dehydrogenase 1 (IDH1) at R132 (IDH1R132MUT) is frequent in low-grade diffuse gliomas and, within glioblastoma (GBM), has been proposed as a marker for GBMs that arise by transformation from lower-grade gliomas, regardless of clinical history. To determine how GBMs arising with IDH1R132MUT differ from other GBMs, we undertook a comprehensive comparison of patients presenting clinically with primary GBM as a function of IDH1R132 mutation status. Patients and Methods In all, 618 treatment-naive primary GBMs and 235 lower-grade diffuse gliomas were sequenced for IDH1R132 and analyzed for demographic, radiographic, anatomic, histologic, genomic, epigenetic, and transcriptional characteristics. Results Investigation revealed a constellation of features that distinguishes IDH1R132MUT GBMs from other GBMs (including frontal location and lesser extent of contrast enhancement and necrosis), relates them to lower-grade IDH1R132MUT gliomas, and supports the concept that IDH1R132MUT gliomas arise from a neural precursor population that is spatially and temporally restricted in the brain. The observed patterns of DNA sequence, methylation, and copy number alterations support a model of ordered molecular evolution of IDH1R132MUT GBM in which the appearance of mutant IDH1 protein is an initial event, followed by production of p53 mutant protein, and finally by copy number alterations of PTEN and EGFR. Conclusion Although histologically similar, GBMs arising with and without IDH1R132MUT appear to represent distinct disease entities that arise from separate cell types of origin as the result of largely nonoverlapping sets of molecular events. Optimal clinical management should account for the distinction between these GBM disease subtypes.

Glioblastoma can suppress immunity by using surface PD-L1 on extracellular vesicles to block T cell receptor–mediated T cell activation.

Glioblastoma multiforme (GBM) is the most frequent and aggressive brain tumor in adults. The dogma that GBM spread is restricted to the brain was challenged by reports on extracranial metastases after organ transplantation from GBM donors. We identified circulating tumor cells (CTCs) in peripheral blood (PB) from 29 of 141 (20.6%) GBM patients by immunostaining of enriched mononuclear cells with antibodies directed against glial fibrillary acidic protein (GFAP). Tumor cell spread was not significantly enhanced by surgical intervention. The tumor nature of GFAP-positive cells was supported by the absence of those cells in healthy volunteers and the presence of tumor-specific aberrations such as EGFR gene amplification and gains and losses in genomic regions of chromosomes 7 and 10. Release of CTCs was associated with EGFR gene amplification, suggesting a growth potential of these cells. We demonstrate that hematogenous GBM spread is an intrinsic feature of GBM biology.

The World Health Organization (WHO) classification and grading system attempts to predict the clinical course of meningiomas based on morphological parameters. However, because of high interobserver variation of some criteria, more reliable prognostic markers are required. Here, we assessed the TERT promoter for mutations in the hotspot regions C228T and C250T in meningioma samples from 252 patients. Mutations were detected in 16 samples (6.4% across the cohort, 1.7%, 5.7%, and 20.0% of WHO grade I, II, and III cases, respectively). Data were analyzed by t test, Fisher's exact test, log-rank test, and Cox proportional hazard model. All statistical tests were two-sided. Within a mean follow-up time in surviving patients of 68.1 months, TERT promoter mutations were statistically significantly associated with shorter time to progression (P < .001). Median time to progression among mutant cases was 10.1 months compared with 179.0 months among wild-type cases. Our results indicate that the inclusion of molecular data (ie, analysis of TERT promoter status) into a histologically and genetically integrated classification and grading system for meningiomas increases prognostic power. Consequently, we propose to incorporate the assessment of TERT promoter status in upcoming grading schemes for meningioma.

Purpose: Expression of the receptor tyrosine kinase c-Met and its ligand scatter factor/ hepatocyte growth factor (SF/HGF) are strongly increased in glioblastomas, where they promote tumor proliferation, migration, invasion, and angiogenesis.We used a novel one-armed anti-c-Met antibody to inhibit glioblastoma growth in vivo. Experimental Design: U87 glioblastoma cells (c-Met and SF/HGF positive) or G55 glioblastoma cells (c-Met positive and SF/HGF negative) were used to generate intracranial orthotopic xenografts in nude mice. The one-armed 5D5 (OA-5D5) anti-c-Met antibody was infused intratumorally using osmotic minipumps. Following treatment, tumor volumes were measured and tumors were analyzed histologically for extracellular matrix (ECM) components and proteases relevant to tumor invasion. Microarray analyses were done to determine the effect of the antibody on invasion-related genes.Results: U87 tumor growth, strongly driven by SF/HGF, was inhibited >95% with OA-5D5 treatment. In contrast, G55 tumors, which are not SF/HGF driven, did not respond to OA-5D5, suggesting that the antibody can have efficacy in SF/HGF-activated tumors. In OA-5D5-treated U87 tumors, cell proliferation was reduced >75%, microvessel density was reduced >90%, and apoptosis was increased >60%. Furthermore, OA-5D5 treatment decreased tumor cell density >2-fold, with a consequent increase in ECM deposition and increased immunoreactivity for laminin, fibronectin, and tenascin. Microarray studies showed no incresae in these ECM factors, rather down-regulation of urokinase-type plasminogen activator and matrix metalloproteinase 16 in glioblastoma cells treated with OA-5D5. Conclusions: Local treatment with OA-5D5 can almost completely inhibit intracerebral glioblastoma growth when SF/HGF is driving tumor growth. The mechanisms of tumor inhibition include antiproliferative, antiangiogenic, and proapoptotic effects.