CHARACTERIZATION OF QUINONE REDUCTASE, GLUTATHIONE AND GLUTATHIONE-S-TRANSFERASE IN HUMAN MYELOID CELL-LINES - INDUCTION BY 1,2-DITHIOLE-3-THIONE AND EFFECTS ON HYDROQUINONE-INDUCED CYTOTOXICITY

In this study, we have characterized quinone reductase (QR), glutathio ne (GSH), glutathione S-transferase (GST) and their induction by a che moprotector, 1,2-dithiole-3-thione (D3T), in the human myeloid cell li nes ML-1 and HL-60. In addition, we also examined the toxicity of hydr oquinone (HQ), a benzene metabolite, to these two cell lines. Both of the cell lines contain a basal level of cellular GSH, which is similar in the two cell lines. Although ML-1 cells contain much higher QR spe cific activity than HL-60 cells, which are relatively QR deficient, th e GST specific activity of ML-1 cells is 1.8 times less than that of H L-60 cells. Immunoblot experiments showed that the GST in these two ce ll lines is GST pi. In addition, HL-60 cells exhibit 4.5 times more my eloperoxidase specific activity than ML-1 cells. Inclusion of D3T in t he cultures could induce significant increases in cellular GSH content and QR activity, but not GST activity in either cell line. Treatment with HQ caused both inhibition of cell proliferation and loss of cell viability in these two myeloid cell lines. HQ treatment also resulted in a significant depletion of cellular GSH, which preceded the loss of cell viability. Pretreatment of both cell lines with buthionine sulfo ximine, an inhibitor of GSH biosynthesis, markedly increased HQ-induce d toxicity. In contrast, the presence of dicumarol, a QR inhibitor, fa iled to potentiate HQ-induced toxicity in ML-1 cells. On the other han d, pretreatment of these two myeloid cell lines with D3T significantly protected against HQ-induced inhibition of cell proliferation and cel l death. Therefore, the above results suggest that GSH but not QR is a n important factor involved in the toxicodynamics of HQ in these myelo id cells.