Glioblastoma is the most common and most aggressive primary brain tumour. Treatment includes surgical removal of the tumour, radiotherapy and chemotherapy with temozolomide. Despite aggressive treatment, the median survival of patients with glioblastoma is only 15 months after diagnosis, and in all cases the disease recurs. Glioblastoma tumour tissue is composed of a heterogeneous population of cells in different stages of differentiation. The low efficacy of glioblastoma treatment is mainly due to the invasion of glioblastoma cells into the brain parenchyma, which makes complete surgical removal of the cancer cells impossible. The MMP-2 and MMP-9 metalloproteases, which degrade components of the extracellular matrix of the brain, play an important role in glioblastoma cell invasion.
The aim of this MSc thesis was to analyse the expression and secretion of MMP-2 and MMP-9 in different glioblastoma cell and organoid models and to determine their role in glioblastoma cell invasion using selective MMP inhibitors. All with the aim to establish in vitro models to study the role of MMP in glioblastoma and test the activity-based probes and inhibitors of MMP-2 and MMP-9.
We found that the two cell lines of differentiated glioblastoma cells and glioblastoma organoids express the metalloproteases MMP-2 and MMP-9, while the cell lines of glioblastoma stem cells do not express MMP-2 and MMP-9. We have shown that MMP-9 is present at a much lower level in the lysate of NIB309 organoids than in the supernatant, whereas MMP-2 is not present in either the lysate or the supernatant of NIB309 organoids. Using gelatin zymography, we found that the pro- and active forms of MMP-2 and MMP-9 are present in the cell lines of the differentiated glioblastoma cells U87 and NIB140, whereas only the pro-forms of MMP-2 and MMP-9 are present in the NIB295 and NIB298 organoids. Using a matrigel spheroid invasion assay, we showed that the broad-spectrum MMP inhibitor batimastat reduces invasion of glioblastoma cells from U87 spheroids and has no effect on invasion of glioblastoma cells from NIB140 spheroids. We also found that the selective inhibitors of MMP-2 and MMP-9, SB-3CT and RXP500.1, do not affect the invasion of glioblastoma cells from U87 and NIB140 spheroids. We were not able to demonstrate the efficacy of activity-based NASA and BBCH probes, which selectively label the active form of MMP-2 and MMP-9, in the U87 glioblastoma cell line.
We have shown that glioblastoma cell lines and organoids express and secrete MMP-2 and MMP-9 at different levels. We have demonstrated the presence of active MMP-2 and MMP-9 in differentiated glioblastoma cells. If MMP-2 and MMP-9 are inhibited in these cells, their activity is likely to be compensated. Using MMP-2 and MMP-9, we have shown that glioblastoma is characterised by intertumor heterogeneity and that personalised treatment is therefore very important. In addition, we have established and characterised in vitro cell models in which new inhibitors and probes for the detection of MMP-2 and MMP-9 can be tested.
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