title: Metabolic adaptation to chronic inhibition of mitochondrial protein synthesis in acute myeloid leukemia cells.
abstract: Recently, we demonstrated that the anti-bacterial agent tigecycline preferentially induces death in leukemia cells through the inhibition of mitochondrial protein synthesis. Here, we sought to understand mechanisms of resistance to tigecycline by establishing a leukemia cell line resistant to the drug. TEX leukemia cells were treated with increasing concentrations of tigecycline over 4 months and a population of cells resistant to tigecycline (RTEX+TIG) was selected. Compared to wild type cells, RTEX+TIG cells had undetectable levels of mitochondrially translated proteins Cox-1 and Cox-2, reduced oxygen consumption and increased rates of glycolysis. Moreover, RTEX+TIG cells were more sensitive to inhibitors of glycolysis and more resistant to hypoxia. By electron microscopy, RTEX+TIG cells had abnormally swollen mitochondria with irregular cristae structures. RNA sequencing demonstrated a significant over-representation of genes with binding sites for the HIF1α:HIF1β transcription factor complex in their promoters. Upregulation of HIF1α mRNA and protein in RTEX+TIG cells was confirmed by Q-RTPCR and immunoblotting. Strikingly, upon removal of tigecycline from RTEX+TIG cells, the cells re-established aerobic metabolism. Levels of Cox-1 and Cox-2, oxygen consumption, glycolysis, mitochondrial mass and mitochondrial membrane potential returned to wild type levels, but HIF1α remained elevated. However, upon re-treatment with tigecycline for 72 hours, the glycolytic phenotype was re-established. Thus, we have generated cells with a reversible metabolic phenotype by chronic treatment with an inhibitor of mitochondrial protein synthesis. These cells will provide insight into cellular adaptations used to cope with metabolic stress.
authors.affiliation: The Princess Margaret Hospital and The Ontario Cancer Institute, University Health Network, Toronto, Canada.
authors.forename: Bozhena
authors.initials: B
authors.lastname: Jhas
authors.forename: Shrivani
authors.initials: S
authors.lastname: Sriskanthadevan
authors.forename: Marko
authors.initials: M
authors.lastname: Skrtic
authors.forename: Mahadeo A
authors.initials: MA
authors.lastname: Sukhai
authors.forename: Veronique
authors.initials: V
authors.lastname: Voisin
authors.forename: Yulia
authors.initials: Y
authors.lastname: Jitkova
authors.forename: Marcela
authors.initials: M
authors.lastname: Gronda
authors.forename: Rose
authors.initials: R
authors.lastname: Hurren
authors.forename: Rob C
authors.initials: RC
authors.lastname: Laister
authors.forename: Gary D
authors.initials: GD
authors.lastname: Bader
authors.forename: Mark D
authors.initials: MD
authors.lastname: Minden
authors.forename: Aaron D
authors.initials: AD
authors.lastname: Schimmer
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D003576:Electron Transport Complex IV / Q000096:biosynthesis* / Q000235:genetics; D015973:Gene Expression Regulation, Leukemic / Q000187:drug effects / Q000235:genetics; D006019:Glycolysis / Q000187:drug effects / Q000235:genetics; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000096:biosynthesis / Q000235:genetics; D015470:Leukemia, Myeloid, Acute / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008911:Minocycline / Q000031:analogs & derivatives / Q000494:pharmacology; D024101:Mitochondrial Proteins / Q000096:biosynthesis* / Q000235:genetics; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics; D010101:Oxygen Consumption / Q000187:drug effects / Q000235:genetics; D014176:Protein Biosynthesis; D000078304:Tigecycline
chemical_list: D000900:Anti-Bacterial Agents; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D024101:Mitochondrial Proteins; D009363:Neoplasm Proteins; D000078304:Tigecycline; D003576:Electron Transport Complex IV; D008911:Minocycline