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Toxicity of Trp-P-2 to cultured human and rat keratinocytes

Keratinocytes cultured from human and rat epidermis exhibited strongly divergent sensitivities to toxicity from the heterocyclic amine food mutagen Trp-P-2. To find a biochemical basis for this difference, the cultured cells were compared in their expression of phase 1 and 2 biotransformation activi...

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Bibliographic Details
Published in:Chemico-biological interactions 2000-07, Vol.127 (3), p.237-253
Main Authors: Chun, Hyang-Sook, Kuzmicky, Paul A., Kado, Norman Y., Rice, Robert H.
Format: Article
Language:English
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Summary:Keratinocytes cultured from human and rat epidermis exhibited strongly divergent sensitivities to toxicity from the heterocyclic amine food mutagen Trp-P-2. To find a biochemical basis for this difference, the cultured cells were compared in their expression of phase 1 and 2 biotransformation activities, mutagenic activation and macromolecular adducts. The human and early passage rat cells expressed similar levels of ethoxyresorufin O-deethylase and N-acetyl transferase activities, their microsomes were similarly active in inducing bacterial mutagenesis when incubated with Trp-P-2, and the keratinocytes accumulated similar levels of DNA adducts over a 4-day treatment period. However, the human cells expressed an order of magnitude higher cytosolic glutathione S-transferase activity than the rat cells, likely providing enhanced protection. Late passage rat epidermal cells were insensitive to Trp-P-2 toxicity, attributable to their rapid loss of measured cytochrome P450 activity. Rat esophageal and fore-stomach epithelial cells resembled late passage rat epidermal cells in their lack of sensitivity to Trp-P-2 toxicity and lack of P450 activity. Human esophageal epithelial cells expressed substantial P450 activity but, in contrast to human epidermal cells, were sensitive to Trp-P-2 toxicity. Thus keratinocytes provide a valuable system in which to examine the basis for species- and tissue-specific differences in toxicity from this carcinogenic heterocyclic amine.
ISSN:0009-2797
1872-7786
DOI:10.1016/S0009-2797(00)00182-4