asbestos--crocidolite and Leukemia--Promyelocytic--Acute

By ESR using 5,5-dimethyl-1-pyrroline-1-oxide as a spin trap, superoxide (O2-) production was proved upon stimulation of dimethyl sulfoxide-differentiated HL60 by crocidolite opsonized with fresh or refrigerated serum, as well as by phorbol myristate acetate (PMA). Crocidolite, unopsonized or opsonized with frozen-thawed or heat-inactivated serum, did not induce O2- release. Addition of iron chelators or superoxide dismutase inhibited O2- release completely. Neither undifferentiated nor PMA-differentiated HL60 released O2- upon stimulation with opsonized crocidolite.

Topics: Asbestos; Asbestos, Crocidolite; Cell Differentiation; Cyclic N-Oxides; Deferoxamine; Dimethyl Sulfoxide; Electron Spin Resonance Spectroscopy; Humans; Kinetics; Leukemia, Promyelocytic, Acute; Pentetic Acid; Spin Labels; Superoxides; Tetradecanoylphorbol Acetate; Time Factors; Tumor Cells, Cultured

It was confirmed that the function of DMSO as an inducer of cell differentiation was suppressed by co-culture of crocidolite asbestos, using the activity of protein kinase C as indicator, because DMSO reacted with .OH radical released by stimulation with crocidolite and wasted itself. SOD inhibited the effect of crocidolite, because SOD reacted with .O2- released by stimulation with crocidolite and inhibited the subsequent development of .OH.

Topics: Asbestos; Asbestos, Crocidolite; Cell Division; Dimethyl Sulfoxide; Free Radicals; Humans; Leukemia, Promyelocytic, Acute; Oxygen; Protein Kinase C; Tumor Cells, Cultured

HL-60 cells were derived from a patient with myelocytic leukemia, and are known to be in the promyelocytic stage and to differentiate into myelocytes or granulocytes after induction with several materials, e.g., DMSO, retinoic acid, and interferons. The authors intended in this report to determine whether asbestos fibers have any effect on the differentiation processes of HL-60 cells induced with DMSO. The cells were induced to differentiate by incubation with 1.25% DMSO for 4 days. A decrease in the percentage of c-myc-protein-positive cells and an increase in the number of C3bi receptor (CD11b) positive cells were observed after differentiation. When crocidolite (50 micrograms/ml) was added to the culture dishes at the beginning of the experiments, the differentiation was inhibited. An increase in the percentage of c-myc-protein-positive cells and a decrease in that of C3bi-receptor-positive cells were observed compared with the cells induced with DMSO alone. It has been reported that DMSO activates phospholipid- and Ca2(+)-dependent protein kinase and induces the differentiation of HL-60 cells. The mechanisms of inhibition by crocidolite fibers of the effects of DMSO remain to be clarified, but the strength of activation of phospholipid- and Ca2(+)-dependent protein kinase may play an important role in the following induction of cell differentiation.

Topics: Asbestos; Asbestos, Crocidolite; Cell Differentiation; Cell Line; Dimethyl Sulfoxide; Humans; In Vitro Techniques; Leukemia, Promyelocytic, Acute