title: NAD(P)H:quinone oxidoreductase-1-dependent and -independent cytotoxicity of potent quinone Cdc25 phosphatase inhibitors.
abstract: Cdc25 dual-specificity phosphatases coordinate cell cycle progression and cellular signaling. Consequently, Cdc25 inhibitors represent potential anticancer agents. We evaluated >10,000 compounds for inhibition of human Cdc25 phosphatases and identified many potent and selective inhibitors, which all contained a quinone. Bioreductive enzymes frequently detoxify or activate quinones. Therefore, we evaluated the effect of NAD(P)H:quinone oxidoreductase-1 (NQO1) and reductase-rich microsomes on the activity of three quinone-containing Cdc25 inhibitors: 2-(2-hydroxyethylsulfanyl)-3-methyl-1,4-naphthoquinone (Cpd 5, compound 5; NSC 672121), 2,3-bis-(2-hydroxyethylsulfanyl)-1,4-naphthoquinone (NSC 95397), and 6-chloro-7-(2-morpholin-4-yl-ethylamino)quinoline-5,8-dione (NSC 663284). Each inhibitor was reduced by human NQO1 (K(m) of 0.3-0.5 microM) but none by microsomes. Compounds were evaluated with six cancer cell lines containing different amounts of NQO1: HT-29 (1056 nmol/mg/min), HCT116 (660 nmol/mg/min), sublines HCT116-R30A (28 nmol/mg/min) and HCT-116R30A/NQ5 (934 nmol/mg/min), MDA-MB-231/Q2 (null NQO1), and subline MDA-MB-231/Q6 (124 nmol/mg/min) but containing similar amounts of microsomal cytochrome P450 reductase and cytochrome b(5) reductase. Growth inhibition and G2/M arrest by Cpd 5 was proportional to NQO1 levels, requiring 4- to 5-fold more Cpd 5 to inhibit HCT-116 or HCT-116R30A/NQ5 compared with HCT-116R30A. In contrast, in all tested cell lines irrespective of NQO1 level, growth inhibition and G2/M arrest by NSC 95375 and NSC 663284 were similar (average IC(50) of 1.3 +/- 0.3 and 2.6 +/- 0.4 microM, respectively). NSC 95375 and NSC 663284 also caused similar Cdk1 hyperphosphorylation, indicating similar Cdc25 inhibition. However, lower Cpd 5 concentrations were needed to produce Cdk1 hyperphosphorylation in sublines with minimal NQO1. Thus, NQO1 detoxified Cpd 5, probably by reducing it to a less active hydroquinone, whereas NSC 95397- and NSC 663284-generated cytotoxicity was unaffected by NQO1.
authors.affiliation: Department of Pharmacology, Hillman Cancer Center, University of Pittsburgh Cancer Institute, 5117 Centre Avenue, Pittsburgh, PA 15213, USA.
authors.forename: Yusheng
authors.initials: Y
authors.lastname: Han
authors.forename: Hongmei
authors.initials: H
authors.lastname: Shen
authors.forename: Brian I
authors.initials: BI
authors.lastname: Carr
authors.forename: Peter
authors.initials: P
authors.lastname: Wipf
authors.forename: John S
authors.initials: JS
authors.lastname: Lazo
authors.forename: Su-shu
authors.initials: SS
authors.lastname: Pan
mesh_terms: D016203:CDC2 Protein Kinase / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002458:Cell Fractionation; D002460:Cell Line; D001728:Dicumarol / Q000494:pharmacology; D016195:G2 Phase / Q000187:drug effects; D019073:HT29 Cells; D006801:Humans; D008861:Microsomes / Q000378:metabolism; D008938:Mitosis / Q000187:drug effects; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000378:metabolism / Q000502:physiology*; D009285:Naphthoquinones / Q000494:pharmacology; D010766:Phosphorylation; D015363:Quinolones / Q000494:pharmacology*; D011809:Quinones / Q000494:pharmacology*; D011994:Recombinant Proteins / Q000378:metabolism; D014407:Tumor Cells, Cultured; D020687:cdc25 Phosphatases / Q000037:antagonists & inhibitors*
chemical_list: C451261:2,3-bis(2-hydroxyethylsulfanyl)-(1,4)naphthoquinone; C440614:NSC 663284; D009285:Naphthoquinones; D015363:Quinolones; D011809:Quinones; D011994:Recombinant Proteins; D001728:Dicumarol; D016660:NAD(P)H Dehydrogenase (Quinone); C447479:NQO1 protein, human; D016203:CDC2 Protein Kinase; D020687:cdc25 Phosphatases