Die membrangebundenen Matrixmetalloproteinasen und ihre Bedeutung für die Astrozytenmigration

Despite all therapeutical progress glial tumors still bear a poor prognosis due to the diffuse infiltration of glioma cells into the surrounding brain – a fact that prevents total resection of the tumor. Furthermore chemotherapy and radiotherapy have only low impact on the growth of the tumour, so new therapy strategies are desperately needed in order to improve the overall survival of patients. Membrane-bound matrix metalloproteinases (MT-MMPs) are a family of 6 endopeptidases that have the potential to increase the invasion and migration of cells. MT-MMPs are overexpressed in astrocytomas, the effect of these proteins, however, is not fully understood. The aim of this study was to further explore the role of MT-MMPs in the pathophysiology of gliomas. To evaluate the effect of the different MT-MMPs, primary murine Tp53 deficient astrocytes (Tp53-/-) were retrovirally transduced with one of the six human MT-MMP genes and the expression of the respective mRNA and protein was determined. Then, the effect of MT-MMP expression on the migratory potential of the transduced cells was evaluated in Scratch and Matrigel Invasion assays. Furthermore, a novel organotypic migration- and invasion assay (OPoSSM (organotypic porcine spinal slice migration) assay) was developed for measuring the migration ability of the astrocytes in porcine spinal cord. In the Scratch-assay all MT-MMPs strongly enhanced the migration of the astrocytes. In contrat to this, the Matrigel Invasion assay was not capable to measure the migration of the astrocytes, because the astrocytes died above the matrigel membrane. Lastly, the OPoSSM assay was an effective, cheap and physiological assay for the investigation of cell migration in CNS white matter. The OPoSSM assay revealed that all MT-MMPs increase the migration of transduced astrocytes and MT4- and MT6-MMP were the most potent mediators of astrocyte migration in porcine spinal cord.