Effects of arsenite on UROtsa cells: Low-level arsenite causes accumulation of ubiquitinated proteins that is enhanced by reduction in cellular glutathione levels

Tiffany G. Bredfeldt, Micheal J. Kopplin, A. Jay Gandolfi

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

Chronic arsenic exposure increases risk for the development of diabetes, vascular disease, and cancers of the skin, lung, kidney, and bladder. This study investigates the effects of arsenite [As(III)] on human urothelial cells (UROtsa). As(III) toxicity was determined by exposing confluent UROtsa cells to As(III) (0.5-200 μM). Depleting cellular glutathione levels with buthionine sulfoximine (BSO) potentiated the toxicity of As(III). Cell viability was assessed with the (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. UROtsa cell ability to biotransform As(III) was determined by dosing cells with environmentally relevant concentrations of As(III) followed by HPLC/ICP-MS analysis of cell media and lysate. Both pentavalent and trivalent monomethylated products were detected. Although cytotoxicity was observed at high doses of As(III) (approximately 100 μM) in UROtsa cells, perturbations of a variety of molecular processes occurred at much lower doses. Exposure to low-level As(III) (0.5-25 μM) causes an accumulation of ubiquitin (Ub)-conjugated proteins. This effect is enhanced when cellular glutathione levels have been reduced with BSO treatment. Because As(III) has many effects on UROtsa cells, a greater understanding of how As(III) is affecting cellular proteins in a target tissue will lead to a better understanding of the mechanism of toxicity and pathogenesis for low-level As(III).

Original languageEnglish (US)
Pages (from-to)412-418
Number of pages7
JournalToxicology and Applied Pharmacology
Volume198
Issue number3
DOIs
StatePublished - Aug 1 2004

Keywords

  • Arsenic methylation
  • Arsenite
  • As(III)
  • Glutathione
  • UROtsa cells
  • Ubiquitin

ASJC Scopus subject areas

  • Toxicology
  • Pharmacology

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