The synergistic effect of radiation and inhibition of SPAK/OSR1 in the reduction of cell proliferation and clonogenic potential in patient-derived GBM cells in vitro
Glioblastoma (GBM) is the most aggressive brain tumor in adults. Cell invasion, migration and proliferation into the heathy brain parenchyma it’s one of the most important challenges in the treatment of this deadly tumor. One potential mechanism that GBM cells can utilize to enhance cell migration and evade pro-apoptotic signals is the tight regulation of cell volume by the STE20/SPS1-Related Proline-Alanine-Rich Protein Kinase (SPAK) and (Oxidative Stress Responsive Kinase 1) OSR1 kinases. Dynamic changes in cell volume can be used by GBM cells to disseminate through the narrow perivascular spaces of the brain. In addition, cancer cells could counteract pro-apoptotic reduction of cell volume by increasing the activity of these kinases. The objective of this project is to test the efficacy of SPAK and OSR1 inhibition alone or in combination with radiotherapy. For this purpose we evaluated the impact of this novel therapy on the proliferation, clonogenicity and apoptosis of primary patient-derived GBM cells in vitro. To achieve our goal we tested a novel SPAK/OSR1 inhibitor (a small molecule called YU566) in two patient derived GBM lines. Cell proliferation and colony formation were determined after treatment using 1uM YU566 alone or in combination with radiotherapy (at different doses 2, 4 Gray (Gy)). We found that radiation and inhibition of SPAK/OSR1 could act in a synergistic fashion, decreasing cell proliferation and clonogenic potential. The next steps in our research will be to determine the mechanisms of cell death and the implications of this therapy in vivo
