Calcium chelator Quin-2 prevents crocidolite-induced DNA strand breakage in human white blood cells.
Exposure of human white blood cells to UICC crocidolite asbestos in vitro resulted in the formation of DNA strand breakage in a dose-dependent manner up to a fibre concentration of 100 micrograms/ml. Subsequent incubations with the iron chelator desferrioxamine or the intracellular Ca2+ chelator Quin-2 prevented DNA strand break formation above control incubations. Addition of aurintricarboxylic acid, an endonuclease inhibitor, similarly abolished crocidolite-induced DNA strand breaks in these cells. These results suggest that crocidolite-derived hydroxyl radicals do not directly induce DNA strand breakage in mammalian white blood cells. In order to assess Ca2+ mobilisation from intracellular stores in control and crocidolite-treated cells, the fullness of these stores was measured by treating with thapsigargin, a specific inhibitor of the endoplasmic reticulum Ca(2+)-ATPase. On addition of thapsigargin to fura-2AM-loaded cells treated with crocidolite we demonstrated that the endoplasmic reticulum stores had been depleted as no further Ca2+ was released, unlike control cells. We suggest that strand breakage is caused by a complex set of events involving oxygen free radicals that may disturb intracellular Ca2+ homoeostasis and the breaks are produced by secondary reactions, involving Ca(2+)-mediated enzymes.
Faux
S P
SP
Institute of Occupational Health, University of Birmingham, Edgbaston.
Michelangeli
F
F
Levy
L S
LS
D000634:Aminoquinolines / Q000494:pharmacology*; D016587:Antimutagenic Agents / Q000494:pharmacology; D017638:Asbestos, Crocidolite / Q000633:toxicity*; D001312:Aurintricarboxylic Acid / Q000494:pharmacology; D002118:Calcium / Q000819:agonists / Q000378:metabolism*; D002614:Chelating Agents / Q000494:pharmacology*; D004249:DNA Damage; D003676:Deferoxamine / Q000494:pharmacology; D005609:Free Radicals / Q000378:metabolism; D006801:Humans; D007962:Leukocytes / Q000187:drug effects; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism
D000634:Aminoquinolines; D016587:Antimutagenic Agents; D002614:Chelating Agents; D005609:Free Radicals; D017382:Reactive Oxygen Species; D017638:Asbestos, Crocidolite; D001312:Aurintricarboxylic Acid; D003676:Deferoxamine; C035739:Quin2; D002118:Calcium