Hemoglobin induction by Ara-C in human erythroleukemic cells (K562) is cell-cycle dependent

This study was undertaken to answer the question of whether chemical induction of hemoglobin in the human erythroleukemic line K562 is cell-cycle dependent. Cells were synchronized with respect to the cell cycle by manipulation of culture conditions. S phase was detected microscopically by immunofluorescent staining. Hemin and arabinofuranosylcytosine (Ara-C) were used to induce hemoglobin synthesis in K562 cells. The action of hemin causes induction without specificity in regard to cell cycle phase, while Ara-C is dependent upon cell cycle phase, with cells within late G1 and early S phases being sensitive to the effect of the agent. These studies also confirm the results that the action of hemin is reversible but the induction caused by Ara-C is irreversible. The synergistic effects of these two inducing agents resulted in a sharper rise in the percentage of induced cells.