TMIC-69. MITOCHONDRIAL TRANSFER FROM ASTROCYTES ENHANCES METABOLISM AND DRIVES PROLIFERATION OF GLIOBLASTOMA

Abstract

Abstract Mitochondrial transfer occurs both in stroke (central nervous system) and inflammatory pain (peripheral nerves). However, its role in glioblastoma (GBM) remains poorly understood. We hypothesized that mitochondrial transfer from non-malignant to GBM cells supports tumor metabolism and growth. Using transgenic mice expressing fluorophore-tagged mitochondria, we found that ~50% of orthotopically-implanted mouse GBM cells acquire mitochondria. Brain-resident cells, especially astrocytes, were the primary mitochondrial donors in vitro and in vivo. Mitochondrial transfer also occurred from immortalized human astrocytes to patient-derived xenograft (PDX) models in vitro at rates of 15-35%. GBM cells that acquired mitochondria expressed higher levels of the ATP-synthase subunit ATP5A and produced more ATP, while metabolomics revealed multiple upregulated pathways in recipient cells. These data point to increased metabolic activity in recipient cells. In vivo, mouse GBM cells that acquired mitochondria were more likely to be in S/G2/M cell cycle phases. We observed a similar effect in PDX that acquired astrocyte mitochondria in vitro, suggesting that transfer drives GBM proliferation. Using sorted mouse and human GBM cells with/without in vitro astrocyte mitochondrial acquisition, we found that mitochondrial transfer promoted in vitro self-renewal and in vivo tumorigenicity, leading to significant reduction in survival and increased penetrance in orthotopic GBM models. Transfer in mouse and human systems was contact-dependent and was abrogated by physical separation of donor and recipient cells by transwell inserts. Pharmacologic inhibition of cytoskeleton and gap junctions did not affect transfer rate, while blocking growth-associated protein 43 (GAP43) function by c-Jun N-terminus kinase inhibition decreased transfer rate by 15-30%, suggesting a potential role of GAP43. Taken together, mitochondrial transfer comprises a fundamental, protumorigenic mechanism of GBM, enhancing metabolic activity and driving tumor cell proliferation. Elucidating the molecular machinery regulating astrocyte mitochondrial transfer and its downstream protumorigenic effects will lead to therapeutic opportunities targeting this understudied tumor microenvironment interaction.