Differentiation of mouse myeloid leukemia cells is inhibited by a factor from non-differentiating leukemia cells.
Mouse myeloid leukemia cells (MI) were induced to differentiate by a factor(s) (D-factor) in ascitic fluid. An inhibitory activity (I-activity) for the induction of differentiation was present in conditioned medium and lysate of MI cells resistant to the D-factor. The I-activity was non-dialyzable, heat-labile and protease-sensitive. Most of the activity was recovered in the fraction precipitated with 30-50% saturated ammonium sulfate. The fraction inhibited induction of phagocytic activity, migrating activity and morphological changes in MI cells, which are typical properties of differentiated MI cells. Low levels of I-activity were detected in conditioned medium or lysate of MI cells sensitive to the D-factor. The resistant MI cells were sensitized to the D-factor by treatment with a low concentration (5-10 ng/ml) of actinomycin D. The I-activity in conditioned medium of actinomycin D-treated resistant cells decreased with development of sensitivity to the D-factor. These results suggest that production of the I-activity in the resistant cells is closely associated with resistance of the MI cells to the D-factor.
D000818:Animals; D001202:Ascitic Fluid / Q000032:analysis*; D002460:Cell Line; D002999:Clone Cells; D003470:Culture Media; D003609:Dactinomycin / Q000494:pharmacology; D004351:Drug Resistance; D005467:Floxuridine; D006131:Growth Inhibitors; D006410:Hematopoiesis / Q000187:drug effects*; D007942:Leukemia, Experimental; D007951:Leukemia, Myeloid; D007962:Leukocytes / Q000187:drug effects*; D051379:Mice; D010447:Peptide Hydrolases / Q000494:pharmacology; D010587:Phagocytosis; D051381:Rats
D003470:Culture Media; D006131:Growth Inhibitors; D005467:Floxuridine; D003609:Dactinomycin; D010447:Peptide Hydrolases