CROCIDOLITE ASBESTOS INCREASED 8-HYDROXYDEOXYGUANOSINE LEVELS IN CELLULAR DNA OF A HUMAN PROMYELOCYTIC LEUKEMIA-CELL LINE, HL-60

Crocidolite, one of the most carcinogenic asbestos fibers, induces the release of reactive oxygen species (ROS) from neutrophils and macrophages. Using HPLC combined with electrochemical detection, we determined that and hydroxy-deoxyguanosine (80HdG), a molecule typical of mutagenic oxidative DNA damage, was induced in the cellular DNA of a human promyelocytic leukemia cell line, HL60, incubated with crocidolite. Crocidolite increased 80HdG in the cellular DNA of phorbol myristate acetate (PMA)-differentiated HL60, which phagocytosed crocidolite. PMA-differentiated HL60 released ROS spontaneously, as determined by ESR with 5,5-dimethylpyrrolone-N-oxide as a spin trap. However, the release of ROS from the cell line did not increase after the addition of crocidolite. The addition of superoxide dismutase at a sufficient concentration to scavenge ROS released from the cell did not inhibit the 80HdG increase induced by crocidolite. Cytochalasin B, which inhibited phagocytosis, did not inhibit the release of ROS. However, it inhibited the crocidolite-induced 80HdG increase by 48.3%. Contrary to PMA-differentiated HL60, undifferentiated HL60 neither phagocytosed crocidolite nor showed a crocidolite-induced increase in 80HdG formation. The 80HdG increase induced by cracidolite was not correlated with ROS release, but with the internalization of crocidolite, suggesting that the increase was not due to an increase in ROS release from the cell but was due to the conversion of relatively inert ROS to highly reactive ROS, such as hydroxyl radicals, by crocidolite that was internalized and close to DNA.