title: NAD(P)H:Quinone oxidoreductase activity is the principal determinant of beta-lapachone cytotoxicity.
abstract: beta-Lapachone activates a novel apoptotic response in a number of cell lines. We demonstrate that the enzyme NAD(P)H:quinone oxidoreductase (NQO1) substantially enhances the toxicity of beta-lapachone. NQO1 expression directly correlated with sensitivity to a 4-h pulse of beta-lapachone in a panel of breast cancer cell lines, and the NQO1 inhibitor, dicoumarol, significantly protected NQO1-expressing cells from all aspects of beta-lapachone toxicity. Stable transfection of the NQO1-deficient cell line, MDA-MB-468, with an NQO1 expression plasmid increased apoptotic responses and lethality after beta-lapachone exposure. Dicoumarol blocked both the apoptotic responses and lethality. Biochemical studies suggest that reduction of beta-lapachone by NQO1 leads to a futile cycling between the quinone and hydroquinone forms, with a concomitant loss of reduced NAD(P)H. In addition, the activation of a cysteine protease, which has characteristics consistent with the neutral calcium-dependent protease, calpain, is observed after beta-lapachone treatment. This is the first definitive elucidation of an intracellular target for beta-lapachone in tumor cells. NQO1 could be exploited for gene therapy, radiotherapy, and/or chemopreventive interventions, since the enzyme is elevated in a number of tumor types (i.e. breast and lung) and during neoplastic transformation.
authors.affiliation: Department of Radiation Oncology, Laboratory of Molecular Stress Responses, Ireland Comprehensive Cancer Center, Case Western Reserve University, Cleveland, Ohio 44106-4942, USA.
authors.forename: J J
authors.initials: JJ
authors.lastname: Pink
authors.forename: S M
authors.initials: SM
authors.lastname: Planchon
authors.forename: C
authors.initials: C
authors.lastname: Tagliarino
authors.forename: M E
authors.initials: ME
authors.lastname: Varnes
authors.forename: D
authors.initials: D
authors.lastname: Siegel
authors.forename: D A
authors.initials: DA
authors.lastname: Boothman
mesh_terms: D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000188:drug therapy / Q000201:enzymology*; D002455:Cell Division / Q000187:drug effects*; D003579:Cytochrome Reductases / Q000378:metabolism; D042966:Cytochrome-B(5) Reductase; D001728:Dicumarol / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D008954:Models, Biological; D009243:NAD / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D009251:NADPH-Ferrihemoprotein Reductase; D009285:Naphthoquinones / Q000494:pharmacology*; D011506:Proteins / Q000378:metabolism; D011808:Quinone Reductases / Q000378:metabolism*; D014162:Transfection; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D014812:Vitamin K / Q000494:pharmacology
chemical_list: D000903:Antibiotics, Antineoplastic; D004791:Enzyme Inhibitors; D009285:Naphthoquinones; D011506:Proteins; D016159:Tumor Suppressor Protein p53; D009243:NAD; D014812:Vitamin K; C014638:beta-lapachone; D001728:Dicumarol; D009247:NADH, NADPH Oxidoreductases; D003579:Cytochrome Reductases; D042966:Cytochrome-B(5) Reductase; D009251:NADPH-Ferrihemoprotein Reductase; C041831:NADH dehydrogenase (quinone); D011808:Quinone Reductases