[Effect of all trans retinoid acid (ATRA) on differentiation and apoptosis of HL-60 cell]

Treatment of premyeloid leukemia with all trans retinoid acid (ATRA) is a milestone in the history of chemotherapy of malignant tumor. Previous studies suggested that the mechanism of treating premyeloid leukemia with ATRA is inducing premyeloid leukemia cells to differentiate along myelocyte lineage, but the fate of differentiated tumor cells is not clear. This study was designed to investigate the relationship between the differentiation of HL-60 induced by ATRA and apoptosis.

HL-60 cells influenced by ATRA (10 micromol/L) capable of inducing differentiation for different time were used as the subject. The differentiation marker on the cell surface and cell cycle were analyzed using flow cytometry. The differentiated cells were identified by confocal microscope after having been stained with propidium iodide (PI). Meanwhile,the changes of the apoptosis of the cells induced by ATRA at different time were analyzed using flow cytometry.

(1)With drug-inducing time increasing, the volume of the differentiated cells was enlarged gradually. After 72 hours, the differentiated cells began to express differentiating marker CD11b and the nuclei morphology of the differentiated cells was changed. (2)After 96 hours of drug-inducing, the induced cells began to show apoptosis peak, but when the cells was washed once after 72 hours of drug-inducing with RPMI 1640 medium and resuspended in RPMI 1640 medium supplemented with 10% fetal calf serum and then cultured in 5%CO2, 37 centigrade for 8 hours,the cells began to show apoptosis peak,and the apoptosis peak was higher than that of the cells after 96 hours of drug-inducing.

ATRA cannot induce HL-60 to achieve terminal differentiation,but the differentiation of HL-60 can be induced by ATRA and the differentiated leukemia cells are easy to apoptosis.