| 1. |
- Karlsson, Christine, et al.
(författare)
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Genetic intratumour heterogeneity in high-grade brain tumours is associated with telomere-dependent mitotic instability.
- 2007
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Ingår i: Neuropathology & Applied Neurobiology. - : Wiley. - 1365-2990 .- 0305-1846. ; 33:4, s. 440-454
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Tidskriftsartikel (refereegranskat)abstract
- Glioblastoma multiforme (GBM) and other high-grade brain tumours are typically characterized by complex chromosome abnormalities and extensive intratumour cytogenetic heterogeneity. The mechanisms behind this diversity have been little explored. In this study, we analysed the pattern of chromosome segregation at mitosis in 20 brain tumours. We found an abnormal segregation of chromatids at mitosis through anaphase bridging (10-25% of anaphase cells) in all 10 GBMs. Anaphase bridging was also found in two medulloblastomas (7-15%), one anaplastic astrocytoma (17%) and one oligodendroglioma (6%). These tumours showed a relatively high degree of cytogenetic complexity and heterogeneity. In contrast, cell division abnormalities were not found in low-grade brain tumours with less complex karyotypes, including two pilocytic astrocytomas and two ependymomas. Further analysis of two GBMs by fluorescence in situ hybridization with telomeric repeat probes revealed excessive shortening of TTAGGG repeats, indicating dysfunctional protection of chromosome ends. In xenografts established from these GBMs, there was a gradual reduction in cytogenetic heterogeneity through successive passages as the proportion of abnormally short telomeres was reduced and the frequency of anaphase bridges decreased from >25% to 0. However, bridging could be reintroduced in late-passage xenograft cells by pharmacological induction of telomere shortening, using a small-molecule telomerase inhibitor. Telomere-dependent abnormal segregation of chromosomes at mitosis is thus a common phenomenon in high-grade brain tumours and may be one important factor behind cytogenetic intratumour diversity in GBM.
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| 2. |
- Persson, Annette, et al.
(författare)
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Cell type- and region- dependent coxsackie adenovirus receptor expression in the central nervous system.
- 2006
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Ingår i: Journal of Neuro-Oncology. - : Springer Science and Business Media LLC. - 1573-7373 .- 0167-594X. ; 78:1, s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- Model systems have shown that adenoviral vector mediated transient gene expression can potentially be applied for the treatment of brain tumours, neurodegenerative diseases and brain injuries. Most studies utilized adenovirus serotype 5 (Ad5) based vectors, which as adhesion molecules require the coxsackie adenovirus receptor (CAR) as a critical determinant for cellular infection. In this report, we have systematically characterized CAR expression in the adult human central nervous system (CNS) by using immunohistochemistry. A total of 85 specimens from various CNS regions were investigated for CAR expression in a cell type-dependent context. The most marked staining positivity was found in the choroid plexus and the pituitary gland. The neocortex had scattered positive neurons, while the white matter was mainly negative. We need to consider the possible adverse effects and the possible damage caused by adenoviral gene therapy if the virus-vector also binds to normal brain cells.
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| 3. |
- Persson, Annette, et al.
(författare)
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Neuroblastomas and medulloblastomas exhibit more Coxsackie adenovirus receptor expression than gliomas and other brain tumors.
- 2007
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Ingår i: Neuropathology. - : Wiley. - 0919-6544 .- 1440-1789. ; 27:3, s. 233-236
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Tidskriftsartikel (refereegranskat)abstract
- Adenoviral vector-mediated treatment is a potential therapy for tumors of the central nervous system. To obtain a significant therapeutic effect by adenoviral vectors, a sufficient infection is required, the power of which depends predominantly on the level of Coxsackie adenovirus receptors. We stained surgical biopsies of central nervous system tumors and neuroblastomas for Coxsackie adenovirus receptors. For gliomas, the level of the receptor was low and markedly variable among individual tumors. By contrast, neuroblastomas and medulloblastomas exhibited a higher degree of Coxsackie adenovirus receptor expression than gliomas and other brain tumors. We conclude that neuroblastomas and medulloblastomas could be suitable for adenovirus-mediated gene therapy. Adverse effects of the treatment, however, must be considered because neurons and reactive astrocytes also express a significant amount of the receptor.
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| 4. |
- Persson, Oscar, et al.
(författare)
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Microarray analysis of gliomas reveals chromosomal position-associated gene expression patterns and identifies potential immunotherapy targets.
- 2007
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Ingår i: Journal of Neuro-Oncology. - : Springer Science and Business Media LLC. - 1573-7373 .- 0167-594X. ; 85:J1, s. 11-24
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Tidskriftsartikel (refereegranskat)abstract
- Gliomas are among the most aggressive malignant tumors and the most refractory to therapy, in part due to the propensity for malignant cells to disseminate diffusely throughout the brain. Here, we have used 27 K cDNA microarrays to investigate global gene expression changes between normal brain and high-grade glioma (glioblastoma multiforme) to try and better understand gliomagenesis and to identify new therapeutic targets. We have also included smaller groups of grade II and grade III tumors of mixed astrocytic and oligodendroglial origin as comparison. We found that the expression of hundreds of genes was significantly correlated to each group, and employed a naive Bayesian classifier with leave-one-out cross-validation to accurately classify the samples. We developed a novel algorithm to analyze the gene expression data from the perspective of chromosomal position, and identified distinct regions of the genome that displayed coordinated expression patterns that correlated significantly to tumor grade. The regions identified corresponded to previously known genetic copy number changes in glioma (e.g. 10q23, 10q25, 7q, 7p) as well as regions not previously associated significantly with glioma (e.g. 1p13, 6p22). Furthermore, to enrich for more suitable targets for therapy, we took a bioinformatics approach and annotated our signatures with two published datasets that identified membrane/secreted genes from cytosolic genes. The resulting focused list of 31 genes included interesting novel potential targets as well as several proteins already being investigated for immunotherapy (e.g. CD44 and tenascin-C). Software for the chromosome analysis was developed and is freely available at http://base.thep.lu.se.
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| 5. |
- Rebetz, Johan, et al.
(författare)
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Glial Progenitor-Like Phenotype in Low-Grade Glioma and Enhanced CD133-Expression and Neuronal Lineage Differentiation Potential in High-Grade Glioma
- 2008
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:6, s. 1107-1107
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Tidskriftsartikel (refereegranskat)abstract
- Background: While neurosphere-as well as xenograft tumor-initiating cells have been identified in gliomas, the resemblance between glioma cells and neural stem/progenitor cells as well as the prognostic value of stem/progenitor cell marker expression in glioma are poorly clarified. Methodology/Principal Findings: Viable glioma cells were characterized for surface marker expression along the glial genesis hierarchy. Six low-grade and 17 high-grade glioma specimens were flow-cytometrically analyzed for markers characteristics of stem cells (CD133); glial progenitors (PDGFR alpha, A2B5, O4, and CD44); and late oligodendrocyte progenitors (O1). In parallel, the expression of glial fibrillary acidic protein (GFAP), synaptophysin and neuron-specific enolase (NSE) was immunohistochemically analyzed in fixed tissue specimens. Irrespective of the grade and morphological diagnosis of gliomas, glioma cells concomitantly expressed PDGFRa, A2B5, O4, CD44 and GFAP. In contrast, O1 was weakly expressed in all low-grade and the majority of high-grade glioma specimens analyzed. Co-expression of neuronal markers was observed in all high-grade, but not low-grade, glioma specimens analyzed. The rare CD133 expressing cells in low-grade glioma specimens typically co-expressed vessel endothelial marker CD31. In contrast, distinct CD133 expression profiles in up to 90% of CD45-negative glioma cells were observed in 12 of the 17 high-grade glioma specimens and the majority of these CD133 expressing cells were CD31 negative. The CD133 expression correlates inversely with length of patient survival. Surprisingly, cytogenetic analysis showed that gliomas contained normal and abnormal cell karyotypes with hitherto indistinguishable phenotype. Conclusions/Significance: This study constitutes an important step towards clarification of lineage commitment and differentiation blockage of glioma cells. Our data suggest that glioma cells may resemble expansion of glial lineage progenitor cells with compromised differentiation capacity downstream of A2B5 and O4 expression. The concurrent expression of neuronal markers demonstrates that high-grade glioma cells are endowed with multi-lineage differentiation potential in vivo. Importantly, enhanced CD133 expression marks a poor prognosis in gliomas.
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