Abstract
Glioblastoma (GBM) is the most aggressive of all the brain tumors with a median patient survival less than 15 months. Despite of surgical resection, radiotherapy, and chemotherapy, recurrence rate is almost 100%. A great percentage of GBM tumors (~60%) infiltrate and contact the ventricular-subventricular zone (V-SVZ). Interestingly, these tumors are the most aggressive, and invariably lead to higher distal recurrence rates, shorter time to tumor progression, and lower overall survival of the patient. The reason for this role of V-SVZ-proximity on the outcome of GBM patients is unknown. We suggest that a potential explanation is the interaction of GBM with the V-SVZ. This region is the largest neurogenic niche in the adult brain where neural stem cells (NSCs) give rise to newborn neuroblasts that migrate toward the olfactory bulb. In GBM there is a cell subpopulation called brain tumor stem cells (BTSCs) with NSCs-like characteristics, but with added potential for tumor initiation, recurrence and invasiveness. Tumor microenvironment plays an important role in migration and invasion process. In the present work, we used the total exosome isolation kit to purify Extracellular Vesicles (EVs) from human primary cultures of BTSCs. We determined that BTSCs-derived EVs contain specific information that is transfer to primary cultures of human Neural Progenitors Cells (NPCs) modulating their proliferation rate, cell viability, and migration. In addition, we identify that NPCs taken up BTSCs-derived EVs and significantly increase the expression levels of stemness-related genes such as Nestin, Nanog, and Sox2, suggesting that a phenotypic transdifferentiation is being carry out. These results support our hypothesis that GBM modulate the tumor microenvironment close to the V-SVZ by releasing EVs that target cellular components in this region and promote their phenotypic transformation, highlighting that NPCs biology changes in the context of tumor environment.
STEM-21. INVESTIGATING DOT1L AS AN EPIGENETIC VULNERABILITY IN BRAIN TUMOR STEM CELLS
