title: Effects of co-administration of dietary sodium arsenite and an NADPH oxidase inhibitor on the rat bladder epithelium.
abstract: Arsenite (As(III)), an inorganic arsenical, is a known human carcinogen, inducing tumors of the skin, urinary bladder and lung. It is metabolized to organic methylated arsenicals. Oxidative stress has been suggested as a mechanism for arsenic-induced carcinogenesis. Reactive oxygen species (ROS) can be important factors for carcinogenesis and tumor progression. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is known to produce intracellular ROS, therefore, we investigated the ability of apocynin (acetovanillone), an NADPH oxidase inhibitor, to inhibit the cytotoxicity and regenerative cell proliferation of arsenic in vitro and in vivo. Apocynin had similar effects in reducing the cytotoxicity of As(III) and dimethylarsinous acid (DMA(III)) in rat urothelial cells in vitro. When tested at the same concentrations as apocynin, other antioxidants, such as l-ascorbate and N-acetylcysteine, did not inhibit As(III)-induced cytotoxicity but they were more effective at inhibiting DMA(III)-induced cytotoxicity compared with apocynin. In vivo, female rats were treated for 3 weeks with 100ppm As(III). Immunohistochemical staining for 8-hydroxy-2'-deoxyguanosine (8-OHdG) showed that apocynin reduced oxidative stress partially induced by As(III) treatment on rat urothelium, and significantly reduced the cytotoxicity of superficial cells detected by scanning electron microscopy (SEM). However, based on the incidence of simple hyperplasia and the bromodeoxyuridine (BrdU) labeling index, apocynin did not inhibit As(III)-induced urothelial cell proliferation. These data suggest that the NADPH oxidase inhibitor, apocynin, may have the ability to partially inhibit arsenic-induced oxidative stress and cytotoxicity of the rat bladder epithelium in vitro and in vivo. However, apocynin did not inhibit the regenerative cell proliferation induced by arsenite in a short-term study.
authors.affiliation: Department of Pathology and Microbiology and the Eppley Institute for Cancer Research, University of Nebraska Medical Center, Omaha, NE 68198-3135, USA.
authors.forename: Shugo
authors.initials: S
authors.lastname: Suzuki
authors.forename: Lora L
authors.initials: LL
authors.lastname: Arnold
authors.forename: Karen L
authors.initials: KL
authors.lastname: Pennington
authors.forename: Satoko
authors.initials: S
authors.lastname: Kakiuchi-Kiyota
authors.forename: Samuel M
authors.initials: SM
authors.lastname: Cohen
mesh_terms: D000080242:8-Hydroxy-2'-Deoxyguanosine; D000098:Acetophenones / Q000008:administration & dosage / Q000494:pharmacology*; D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000008:administration & dosage / Q000494:pharmacology*; D018053:Arsenites / Q000008:administration & dosage / Q000633:toxicity*; D001205:Ascorbic Acid / Q000494:pharmacology; D002101:Cacodylic Acid / Q000031:analogs & derivatives / Q000633:toxicity; D002273:Carcinogens / Q000008:administration & dosage / Q000633:toxicity*; D002460:Cell Line; D049109:Cell Proliferation; D019610:Cytoprotection; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000378:metabolism; D004032:Diet; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006965:Hyperplasia; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D051381:Rats; D011916:Rats, Inbred F344; D017670:Sodium Compounds / Q000008:administration & dosage / Q000633:toxicity*; D001743:Urinary Bladder / Q000187:drug effects* / Q000201:enzymology / Q000648:ultrastructure; D019459:Urothelium / Q000187:drug effects / Q000201:enzymology
chemical_list: D000098:Acetophenones; D000975:Antioxidants; D018053:Arsenites; D002273:Carcinogens; D004791:Enzyme Inhibitors; D017670:Sodium Compounds; C472511:dimethylarsinous acid; C017947:sodium arsenite; D000080242:8-Hydroxy-2'-Deoxyguanosine; D002101:Cacodylic Acid; C056165:acetovanillone; D019255:NADPH Oxidases; D003849:Deoxyguanosine; D001205:Ascorbic Acid; D000111:Acetylcysteine