Mitofusin-2 mediates doxorubicin sensitivity and acute resistance in Jurkat leukemia cells

Abstract

Mitochondria oscillate along a morphological continuum from fragmented individual units to hyperfused tubular networks. Their position at the junction of catabolic and anabolic metabolism couples this morphological plasticity, called mitochondrial dynamics, to larger cellular metabolic programs, which in turn implicate mitochondria in a number of disease states. In many cancers, fragmented mitochondria engage the cell with the biosynthetic capacity of aerobic glycolysis in service of proliferation and progression. Chemo-resistant cancers, however, favor remodeling dynamics that yield fused mitochondrial assemblies utilizing oxidative phosphorylation (OXPHOS) through the electron transport chain (ETC). In this study, expression of Mitofusin-2 (MFN-2), a GTPase protein mediator of mitochondrial fusion, was found to closely correlate to Jurkat leukemia cell survival post doxorubicin (DxR) assault. Moreover, this was accompanied by dramatically increased expression of OXPHOS respiratory complexes and ATP Synthase, as well as a commensurate escalation of state III respiration and respiratory control ratio (RCR). Importantly, CRISPR knockout of MFN-2 resulted in a considerable decrease of doxorubicin (DxR) median lethal dose compared to a treated wildtype control, suggesting an important role of mitochondrial fusion in chemotherapy sensitivity and acute resistance.