Changes in Cu,Zn-superoxide dismutase gene during induced erythroid and myeloid differentiation

We investigated the alteration of Cu,Zn-superoxide dismutase during erythroid and myeloid differentiation in order to elucidate its physiological significance in different types of cells. We measured enzyme activity and mRNA levels of superoxide dismutase in the process of differentiation to erythroid cells or myeloid cells. When human leukemia K562 cells are incubated in the presence of 80 microM hemin, benzidine-positive cells appear on day 1 and 80% of the cells become positive on day 5. During hemin-induced erythroid differentiation, Cu,Zn-superoxide dismutase activity increases 3.5-fold of the initial value and mRNA for Cu,Zn-superoxide dismutase increases prior to the activity to the same extent. On the other hand, when human promyelocytic leukemia HL-60 cells are incubated in the presence of 1.3% dimethyl sulfoxide, nitroblue tetrazolium-positive cells reach approximately 90% on day 5. During dimethyl sulfoxide-induced myeloid differentiation, the activity of Cu,Zn-superoxide dismutase decreases below 15% of the initial value on day 5 and mRNA for Cu,Zn-superoxide dismutase decreases as well. The results indicate that the synthesis of superoxide dismutase is linked with either the erythroid or myeloid differentiation program.