Production of differentiation-stimulating factor in cultured mouse myeloid leukemia cells treated by glucocorticoids

Abstract

Mouse myeloid leukemic cells (Ml) could be induced by glucocorticoids to produce a factor(s) stimulating their own differentiation to macrophage- and granulocyte-like cells. The differentiation-stimulating factor(s) (DSF) was not due to a contaminating steroid, although glucocorticoids were effective to induce differentiation of the cells. DSF seemed to be a glycoprotein(s) with a molecular weight of 20 000–40 000 D, since it was susceptible to a treatment of proteases of glycosidases. The inducing ability of corticoids to produce DSF was correlated with their glucocorticoid activity, which was in parallel with the inducing activity of cell differentiation. Moreover, glucocorticoids were unable to stimulate the production of DSF in a dexamethasoneresistant Ml cells which could not differentiate even in a high concentration of dexamethasone. These results suggest that production of DSF in Ml cells was closely associated with differentiation of the cells. Differentiation of Ml cells by DSF was confirmed by morphological, functional and biochemical evidences.