Mitochondrial Dynamics Participate in an Early Metabolic Adaptation of Glioblastoma Multiforme T98G Cells to Doxorubicin-Induced Chemotherapeutic Stress.

Chemotherapy-induced metabolic reprogramming of glioblastoma multiforme (GBM) cells increases intracellular levels of reductive and energetic carriers, thereby fueling drug-relocation and retention systems and enhancing GBM drug-resistance. We have previously shown the role of this process in the adaptation of poly(morpho)nuclear "giant" cells (PGCs) in T98G populations to doxorubicin (DOX)-induced stress. Here, we addressed the role of a "resistance triad", which coordinates metabolic T98G reprogramming with the activation of the drug-relocation and drug-retention axis, in the recovery of GBM populations from chemotherapeutic stress. A combination of proteomic analyses with metabolic and phenotypic profiling of pulse DOX-treated T98G cells revealed the significance of mitochondrial dynamics for the efficiency of the T98G "resistance triad". DOX-induced mobilization of ATP-generating systems and ATP-dependent anabolic pathways was accompanied by the formation of DOX-negative, "mosaic" mitochondrial networks and the upregulation of mitofusin-2 (MFN2) in T98G PGCs. Transient MFN2 down-regulation correlated with the respiratory capacity of T98G cells, while impairing cell welfare in the absence and presence of DOX. However, minute fractions of PGCs, which withstood combined MFN2 down-regulation and pulse DOX treatment, retained mitochondrial networks and displayed efficient ABC transporter-/V-type channel-dependent lysosomal DOX retention. Collectively, a "triad" of mitochondrial activation, ABC transporter-dependent perinuclear redistribution and V-type channel-mediated lysosomal DOX compartmentalization determines DOX resistance of T98G cells. Whereas MFN2-dependent mitochondrial rearrangements may contribute to these processes, complementary adaptative mechanisms can compensate MFN2 dysfunction, limiting its potential as a therapeutic target.