Induction of murine erythroleukemia differentiation by actinomycin D

Abstract

Mouse friend erythroleukemia cells are induced to differentiate by 0.5-5 ng of actinomycin D per ml. Murine erythroleukemia cells cultured with actinomycin D prolong cell doubling time but achieve the same density after 5 days as cells without inducer. Actinomycin D causes over 95% of the cells to become benzidine-reactive. [3H]Actinomycin D uptake into DNA can be detected withon 2 h and reaches a maximum (approximately 0.1 pmol/106 cells) by 10-12 h. About 1 of 105 dG.cntdot.dC pairs is bound to actinomycin D. Commitment to differentiation, assayed by transfer of cells to culture without inducer, was detected as early as 5 h. Unlike Me2SO [dimethyl sulfoxide], which causes a transient prolongation in G1 at about 15-20 h cells cultured with actinomycin D show a more sustained increase in the proportion of the cells in G1. Globin mRNA accumulation was detectable by 19 h in culture. Alteration in DNA stability in alkaline sucrose gradients was detected by 19 h. Actinomycin D induces synthesis of Hbmaj and Hbmin in approximately equal amounts. A decrease in rates of synthesis of RNA, DNA and total proteins occur in cell cultured with actinomycin D, as well as in cells cultured with Me2SO. No evidence for early action of actinomycin D at the plasma membrane was obtained by measurement of changes in cell volume or 86RbCl uptake. Taken together, the present results indicate that actinomycin D is a potent inducer of differentiation of murine erythroleukemia cells and the target of its effect may be at the level of DNA.