Astrocytes: A Driving Force in Tumor and Substance Abuse Disorders

Astrocytes were historically considered passive supporters of neuronal cell architecture and function, lacking excitability, and having no role in signal integration. Recent literature has progressively challenged this, showcasing active participation of astrocytes for critical functions in the brain, including blood-brain-barrier manipulation, neurogenesis, and ionic homeostasis maintenance. This dissertation presents evidence for the major contribution of astrocytes in two different but significant brain disorders—Glioblastoma (GBM) and Substance Abuse Disorders. Firstly, we explored the role of astrocytes in glioblastoma growth, patient survival, and metabolic reprogramming through in silico and in vitro studies. We developed a novel technology enabling us to engineer patterned co-culture of astrocytes and GBM cells. Using layer-by-layer assembly and microcapillary force driven in vitro patterning, we demonstrated physical contact with astrocytes results in significant upregulation in energy utilization of glioblastoma cells when grown in co-culture with astrocytes compared to both transwell co-culture and monoculture glioma cells. We also observed a significant change in metabolism-related and signaling-related proteins and significant upregulation of the transcription of genes involved in energy metabolism. Overall, we demonstrated astrocytes drive metabolic reprogramming and growth in GBM. Secondly, we investigated the effects of sub-toxic levels of methamphetamine (METH) on primary cortical astrocytes. After 24-hour treatment with 1 and 5 mM METH, we observed an increase in the accumulation of autophagy-related vesicles and an increase in the relative expression of ER stress genes. Concurrent treatment with, FDA approved antioxidant, BG-12 was able to reverse METH-induced cell death in astrocytes. Additionally, we observed an increase in glycolytic activity and glycolytic capacity in response to METH when astrocytes were cultured in healthy brain stiffness (2 kPa), but not in diseased brain stiffness (8 kPa). Taken together, this highlights the critical role of astrocytes with dynamic changes in brain microenvironment as a possible driver of metabolic dysfunction in substance abuse disorders. Overall, my thesis spotlights key roles of astrocytes in tumor and substance abuse disorders and may have important therapeutic implications in the future