Expression of c-myc proto-oncogene during podophyllotoxin induced IW32 erythroleukemia cell differentiation.

The effect of hemin or podophyllotoxin on the differentiation of the erythropoietin (epo)-producing IW32 erythroleukemia cells was investigated. Podophyllotoxin induced IW32 cells to differentiate, and hemin potentiated the differentiation. Hemin had no effect on cell proliferation whereas podophyllotoxin inhibited cell growth. c-myc mRNA levels decreased biphasically by hemin or podophyllotoxin, while the combined treatment of hemin plus podophyllotoxin did not result in the initial decrease in c-myc mRNA level. Our data suggested that down-regulation of c-myc expression was not a prerequisite of IW32 cell differentiation induced by hemin and podophyllotoxin combined.