title: Inhibition of mitochondrial respiration: a novel strategy to enhance drug-induced apoptosis in human leukemia cells by a reactive oxygen species-mediated mechanism.
abstract: Cancer cells are under intrinsic increased oxidative stress and vulnerable to free radical-induced apoptosis. Here, we report a strategy to hinder mitochondrial electron transport and increase superoxide O2. radical generation in human leukemia cells as a novel mechanism to enhance apoptosis induced by anticancer agents. This strategy was first tested in a proof-of-principle study using rotenone, a specific inhibitor of mitochondrial electron transport complex I. Partial inhibition of mitochondrial respiration enhances electron leakage from the transport chain, leading to an increase in O2. generation and sensitization of the leukemia cells to anticancer agents whose action involve free radical generation. Using leukemia cells with genetic alterations in mitochondrial DNA and biochemical approaches, we further demonstrated that As2O3, a clinically active anti-leukemia agent, inhibits mitochondrial respiratory function, increases free radical generation, and enhances the activity of another O2.-generating agent against cultured leukemia cells and primary leukemia cells isolated from patients. Our study shows that interfering mitochondrial respiration is a novel mechanism by which As2O3 increases generation of free radicals. This novel mechanism of action provides a biochemical basis for developing new drug combination strategies using As2O3 to enhance the activity of anticancer agents by promoting generation of free radicals.
authors.affiliation: Department of Molecular Pathology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: Hélène
authors.initials: H
authors.lastname: Pelicano
authors.forename: Li
authors.initials: L
authors.lastname: Feng
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhou
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Carew
authors.forename: Elizabeth O
authors.initials: EO
authors.lastname: Hileman
authors.forename: William
authors.initials: W
authors.lastname: Plunkett
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Keating
authors.forename: Peng
authors.initials: P
authors.lastname: Huang
mesh_terms: D000077584:2-Methoxyestradiol; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D000077237:Arsenic Trioxide; D001152:Arsenicals / Q000494:pharmacology; D002478:Cells, Cultured; D004958:Estradiol / Q000031:analogs & derivatives*; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D010087:Oxides / Q000494:pharmacology; D010101:Oxygen Consumption / Q000187:drug effects*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012402:Rotenone / Q000494:pharmacology; D013481:Superoxides / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D001152:Arsenicals; D010087:Oxides; D017382:Reactive Oxygen Species; D012402:Rotenone; D013481:Superoxides; D004958:Estradiol; D000077584:2-Methoxyestradiol; D000077237:Arsenic Trioxide