[Effects of differentiation status on apoptosis of human leukemia HL60 cells]

The effects of differentiation of human leukemia HL60 cells on harringtonine(Har) and camptothecin(Cam) induced apoptosis(in these cells) were studied. When treated with phorbol 12-myriate, 13-acetate 16 nmol.L-1 for 24 h, the HL60 cells differentiated into monocyte/macrophage cells and were arrested at G1 phase. The differentiated cells were shown to be resistant to the Har and Cam induced apoptosis, but showed no change of expression of c-myc gene. HL60 cells incubated in 1.4% dimethyl sulfoxide for 48 h differentiated into granulocyte cells and were also gene arrested at G1 phase. The differentiated cells became resistant to the apoptosis induced by Cam, but not that by Har, and expression of c-myc decreased drastically in the differentiated cells. The results indicate that the differentiated status of human leukemia HL60 cells apparently affected the apoptosis induced by harringtonine and camptothecin, but it was irrelevant to the change of the expression of c-myc gene.