Toxicity and metabolism of subcytotoxic inorganic arsenic in human renal proximal tubule epithelial cells (HK-2)

M. A. Peraza, D. E. Carter, A. Jay Gandolfi

Research output: Contribution to journalArticlepeer-review

40 Scopus citations

Abstract

Arsenic is an environmental toxicant and a human carcinogen. The kidney, a known target organ of arsenic toxicity, is critical for both in vivo arsenic biotransformation and elimination. This study investigates the potential of an immortalized human proximal tubular epithelial cell line, HK-2, to serve as a representative model for low level exposures of the human kidney to arsenic. Subcytotoxic concentrations of arsenite (≥10 μmol/L) and arsenate (< 100 μmol/L) were determined by leakage of LDH from cells exposed for 24 h. Threshold concentrations of arsenite (between 1 and 10 μmol/L) and arsenate (between 10 and 25 μmol/L) were found to affect MTT processing by mitochondria. Biotransformation of subcytotoxic arsenite or arsenate was determined using HPLC-ICP-MS to detect metabolites in cell culture media and cell lysates. Following 24 h, analysis of media revealed that arsenite was minimally oxidized to arsenate and arsenate was reduced to arsenite. Only arsenite was detected in cell lysates. Pentavalent methylated arsenicals were not detected in media or lysates following exposure to either inorganic arsenical. The activities of key arsenic biotransformation enzymes - MMA V reductase and AsIII methyltransferase - were evaluated to determine whether HK-2 cells could reduce and methylate arsenicals. When compared to the activities of these enzymes in other animal tissues, the specific activities of HK-2 cells were indicative of a robust capacity to metabolize arsenic. It appears this human renal cell line is capable of biotransforming inorganic arsenic compounds, primarily reducing arsenate to arsenite. In addition, even at low concentrations, the mitochondria are a primary target for toxicity.

Original languageEnglish (US)
Pages (from-to)253-264
Number of pages12
JournalCell Biology and Toxicology
Volume19
Issue number4
DOIs
StatePublished - Aug 2003

Keywords

  • Arsenic
  • Biotransformation
  • Human kidney cell line
  • Nephrotoxicity

ASJC Scopus subject areas

  • Toxicology
  • Cell Biology
  • Health, Toxicology and Mutagenesis

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