Expression of c-myc changes during differentiation of mouse erythroleukaemia cells

The transforming gene of avian myelocytomatosis virus MC29, v-myc, causes a variety of malignancies in chickens¹. A cellular homologue ², c-myc, has been implicated in B-cell malignancies in mice and humans^3-6 but is also expressed in many normal cell types⁷ and may be important in the control of normal cell proliferation⁸, c-myc is highly conserved in vertebrates⁹. We have been investigating the relationship between c-myc expression and the terminal differentiation of cultured mouse erythroleukaemia (MEL) cells. We find that the level of c-myc messenger RNA shows a rapid biphasic change in MEL cells induced to differentiate by dimethyl sulphoxide or hypoxanthine. The changes occur during the first few hours of the differentiation programme and require active protein synthesis. These data suggest that changes in c-myc expression may be important in the irreversible commitment of MEL cells to terminal erythroid differentiation.