Erythroid and megakaryocytic differentiation of K562 erythroleukemic cells by monochloramine.

The induction of leukemic cell differentiation is a hopeful therapeutic modality. We studied the effects of monochloramine (NH2Cl) on erythroleukemic K562 cell differentiation, and compared the effects observed with those of U0126 and staurosporine, which are known inducers of erythroid and megakaryocytic differentiation, respectively. CD235 (glycophorin) expression, a marker of erythroid differentiation, was significantly increased by NH2Cl and U0126, along with an increase in cd235 mRNA levels. Other erythroid markers such as γ-globin and CD71 (transferrin receptor) were also increased by NH2Cl and U0126. In contrast, CD61 (integrin β3) and CD42b (GP1bα) expression, markers of megakaryocytic differentiation, was increased by staurosporine, but did not change significantly by NH2Cl and U0126. NH2Cl retarded cell proliferation without a marked loss of viability. When ERK phosphorylation (T202/Y204) and CD235 expression were compared using various chemicals, a strong negative correlation was observed (r = -0.76). Paradoxically, NH2Cl and staurosporine, but not U0126, induced large cells with multiple or lobulated nuclei, which was characteristic to megakaryocytes. NH2Cl increased the mRNA levels of gata1 and scl, decreased that of gata2, and did not change those of pu.1 and klf1. The changes observed in mRNA expression were different from those of U0126 or staurosporine. These results suggest that NH2Cl induces the bidirectional differentiation of K562. Oxidative stress may be effective in inducing leukemic cell differentiation.