EFFECTS OF SMALL MOLECULE INHIBITORS ON MOTILITY AND PROLIFERATION OF UNDIFFERENTIATED, DIFFERENTIATED, AND IRRADIATED GLIOBLASTOMA STEM CELLS

Abstract

Glioblastoma (GBM) is an aggressive and incurable form of brain cancer. Glioblastoma stem cells (GSCs) make GBM treatment difficult as they invade surrounding brain tissue and are resistant to radiation and chemotherapy. Decreased motility and proliferation of GBM cells from established glioblastoma cell lines was previously observed when using small-molecule inhibitors fibroblast growth factor receptor inhibitor PD173074, focal adhesion kinase inhibitors PF431396 and Y15, and αvβ3/αvβ5 integrin inhibitor cilengitide. In this research it was found these inhibitors were similarly effective at decreasing the motility of patient-derived GSCs. These results were expanded to test the hypothesis that motility and proliferation of “differentiated” and irradiated GSCs would be similarly inhibited. GSCs were cultured in high-serum media to induce a differentiated state. Some of these “differentiated” GSCs were later cultured in stem cell media. A “super scratch” assay measured the velocity of migrating cells exposed to the inhibitors using time-lapse microscopy. A proliferation assay was then performed to determine the percentage of cells in S phase of the cell cycle. All cell lines exhibited similar decreases in motility following inhibitor treatment. The “differentiated” GSCs exhibited slower overall motility, but “differentiated” GSCs put back into stem-cell media exhibited similar motility as regular GSCs pre-differentiation. The proliferation assay showed that “differentiated” GSCs exhibited increased proliferation rates overall. The irradiated GSCs exhibited similar responses to the inhibitors compared to non-irradiated GSCs in the motility and proliferation assays. These results suggest the small molecule inhibitors tested may be effective against both GSCs and differentiated GBM cells and provide evidence that GSCs can enter in and out of a differentiated state depending on the extracellular environment. Radiation also did not change the response to drug treatments, which indicates radiation may not impact the efficacy of chemotherapeutics during glioblastoma treatment.