„Glioblastoma in a dish“ – Die Etablierung eines Mausmodells für das sekundäre Glioblastom
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Philipps-Universität Marburg
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Abstract
The Glioblastoma multiforme is not only the most common but also the most aggressive brain tumor. The treatment of this desease involves chemotherapy, radiation, radiosurgery, corticosteroids, antiangiogenic therapy, and surgery. Nevertheless the patients´ prognosis is very poor. Although there are some new therapeutic approaches median survival is only about 14 month.
Scientifically there are two different entities – the primary and secondary glioblastoma multiforme, which cannot be distinguished histologically. The tumor shows a rapid diffuse infiltrative growth, polymorphic nuclei, necrosis and angiogenesis. The primary glioblastoma develops de novo. Common mutations seen in primary glioblastomas are loss of heterozygosity of 10q, EGFR-ampilfication and deletion of p16INK4a. There is no evidence of a low-grade neoplasia in diagnostic imaging or histology. In contrast to that the secondary glioblastoma progresses from low-grade or anaplastic astrocytomas into a high-grade lesion. The mutation of the tumor suppressor p53 is often seen in those low-grade lesions.
As already mentioned the glioblastoma multiforme is a very aggressive type of cancer which affects middle-aged people. In order to understand the cancers origin, its metastasis, infiltration and migration good tumor models are needed. Furthermore understanding the tumor biology is also necessary to develop new therapeutic strategies. There have been various approaches in the past to develop a mouse model for the glioblastoma mutiforme. Unfortunately they all were not able to show infiltrative growth in the brain, which is a strong characteristic of that lesion. Besides that there is a deep disagreement in the scientific community whether the glioblastoma multiforme originates from differentiated astrocytes or neural progenitors.
Holland EC et al. were able to create a promising glioblastoma model through gene transfer resulting in an overexpression of K-Ras and Akt in neural progenitors. Furthermore Lassman et al. published a similar tumor model with differentiated astrocytes that showed an undifferentiated phenotype through overexpression of c-Myc.
Following these tumor models this work wanted to create a glioblastoma model from differentiated astrocytes without the overexpression of K-Ras since the mutation of K-Ras is not a common mutation seen in glioblastoma multiforme.
P53 knockout astrocytes from newborn p53 knockout mice were cultured. The cultured astrocytes were infected with a supernatant from cultured Phoenix cells. After transfection with certain plasmids this cell line is capable of producing a retrovirus that is able to infect murine cells. As a result this work was able to create 3 different cell lines: Astrocytes that over expressed Akt, c-Myc or Akt and c-Myc. Through the overexpression of Akt cells were immortalized. In contrast to that c-Myc seemed to be responsible for a rapid growth and an undifferentiated phenotype of the cultures astrocytes. The cultures astrocytes were stained against Ki67, GFAP and against neural progenitor marker like Olig2, Nestin, Musashi-1, CD133 showing a loss of GFAP and a positive immunostaining for the progenitor marker in late cell passages. Using RNA Protection Assay this work was able to proof that our cultures astrocytes did not overexpress neuronal markers like for example neurofilament, synptophysin or calbindin.
Furthermore stereotactic injection was used to place p53 knockout astrocytes that overexpressed Akt and c-Myc in the striatum of Bl6- and RAG2-/- mice. After 21 days animals were sacrificed, cryosections of the brains were made and the resulting tumor was stained with hematoxylin and eosin. To finish tumor sections were stained against CD4, CD8 and Mac-1 showing no infiltration of the immune system in the animals´ brains.
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Created: 2011Issued: 2011-06-28Updated: 2011-08-08
Faculty
Medizin
Publisher
Philipps-Universität Marburg
Language
ger
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DoctoralThesis
Keywords
astrocytomaAktp53glioblastomastereotaxisMyc
DFG-subjects
StereotaxieMycAstrozytomProtein p53Glioblastom
DDC-Numbers
610
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Radke, Josefine: „Glioblastoma in a dish“ – Die Etablierung eines Mausmodells für das sekundäre Glioblastom. : Philipps-Universität Marburg 2011-06-28. DOI: https://doi.org/10.17192/z2011.0430.
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This item has been published with the following license: In Copyright