title: ECTO-NOX target for the anticancer isoflavene phenoxodiol.
abstract: Phenoxodiol, a synthetic isoflavene with clinical efficacy in the management of ovarian and other forms of human cancer, blocked the activity of a cancer-specific and growth-related cell surface ECTO-NOX protein with both oxidative (hydroquinone) and protein disulfide-thiol interchange activity designated tNOX. Purified recombinant tNOX bound phenoxodiol with high affinity (Kd of 50 nM). The tNOX protein appeared to be both necessary and sufficient for the cancer-specific cytotoxicity of phenoxodiol. Growth inhibition of fibroblasts from embryos of mice expressing a tNOX transgene, but not from wild-type mice, was inhibited by phenoxodiol followed by apoptosis. Both the oxidative and protein disulfide-thiol interchange activities that alternate to generate the complex set of oscillations with a period length of 22 min (24 min for the constitutive counterpart CNOX) that characterize ECTO-NOX proteins respond to phenoxodiol. Oxidation of NADH or reduced coenzyme Q10 was rapidly blocked by phenoxodiol. In contrast, the protein disulfidethiol interchange activity measured either by the restoration of activity to scrambled and inactive RNase or from the cleavage of dithiodipyridine (EC50 of 50 nM) was inhibited progressively over an interval of 60 min that spanned three cycles of activity. Inhibition of the latter paralleled the inhibition of cell enlargement and the consequent inability of inhibited cells to initiate traverse of the cell cycle. Activities of constitutive ECTO-NOX (CNOX) forms of either cancer or noncancer cells were unaffected by phenoxodiol to help explain how the cytotoxic effects of phenoxodiol may be restricted to cancer cells.
authors.affiliation: Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA. morre@pharmacy.purdue.edu
authors.forename: D James
authors.initials: DJ
authors.lastname: Morré
authors.forename: P J
authors.initials: PJ
authors.lastname: Chueh
authors.forename: Kader
authors.initials: K
authors.lastname: Yagiz
authors.forename: Andrew
authors.initials: A
authors.lastname: Balicki
authors.forename: Chinpal
authors.initials: C
authors.lastname: Kim
authors.forename: Dorothy M
authors.initials: DM
authors.lastname: Morré
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D019556:COS Cells; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002522:Chlorocebus aethiops; D003067:Coenzymes / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D020128:Inhibitory Concentration 50; D007529:Isoflavones / Q000378:metabolism / Q000494:pharmacology*; D051379:Mice; D008815:Mice, Inbred Strains; D008822:Mice, Transgenic; D009243:NAD / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000235:genetics; D013438:Sulfhydryl Compounds / Q000378:metabolism; D014162:Transfection; D014451:Ubiquinone / Q000031:analogs & derivatives / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D003067:Coenzymes; D004220:Disulfides; D007529:Isoflavones; D034741:RNA, Small Interfering; D013438:Sulfhydryl Compounds; D009243:NAD; D014451:Ubiquinone; C471183:phenoxodiol; D009247:NADH, NADPH Oxidoreductases; C431909:tumor-associated NADH oxidase; C024989:coenzyme Q10