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Characterization of the genotoxicity of nitrilotriacetic acid
Author(s) -
Nesslany Fabrice,
SimarMeintières Sophie,
Watzinger Malene,
Talahari Ismail,
Marzin Daniel
Publication year - 2008
Publication title -
environmental and molecular mutagenesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1
H-Index - 87
eISSN - 1098-2280
pISSN - 0893-6692
DOI - 10.1002/em.20403
Subject(s) - genotoxicity , micronucleus test , comet assay , microbiology and biotechnology , carcinogen , micronucleus , in vivo , apoptosis , dna damage , kidney , mutagen , chemistry , biology , gene mutation , biochemistry , dna , toxicity , mutation , genetics , gene , organic chemistry
The chelating agent nitrilotriacetic acid (NTA), classified as an epigenetic rodent carcinogen, was assessed in the in vivo rodent Comet assay on isolated kidney cells. Unexpected potent increases in DNA damage were obtained in both the short (3–6 hr) and long‐term (22–26 hr) expression times after a single oral treatment at 1,000–2,000 mg/kg bw. NTA was assayed in the Ames test using TA1537, TA98, TA100, and TA102 tester strains, and in the in vitro micronucleus assay on L5178Y mouse lymphoma cells and on CTLL2 and CTLL2/Bcl2 cells coupled to the apoptosis measurement, both with and without metabolic activation by aroclor 1254‐induced liver or kidney rat S9‐mix. Whatever the S9 origin, neither genotoxicity nor apoptosis was detected, while a strong increase in the micronuclei formation was observed without S9 without any apoptosis induction. The direct genotoxicity of NTA was confirmed in the mouse lymphoma tk+/− gene mutation assay and in the chromosomal aberrations test on human lymphocytes. When tested in combination with an excess of Ca 2+ , NTA gave negative results on L5178Y mouse lymphoma cells in the in vitro Comet and micronucleus assays but still induced DNA damage on rat primary kidney cells. The higher sensitivity of renal cells to Ca 2+ variations could explained the positive response observed in vivo. The carcinogenicity of NTA could be a consequence of the survival of kidney cells to intracellular variations of Ca 2+ , leading to a local and indirect genotoxicity. This suggests that threshold dose exists beyond which tumor‐generating events will be displayed. Environ. Mol. Mutagen., 2008. © 2008 Wiley‐Liss, Inc.