ABSTRACT
To investigate the possible mechanisms of nitric oxide (NO)-induced apoptosis in leukemia cell line HL-60, HL-60 cells in vitro were incubated with sodium nitroprusside (SNP), the in situ cell apoptosis quantitatively was assayed by TdT-mediated dUTP nick end labeling (TUNEL), the cell cycle DNA and proteins expression of Bcl-2, Bax, mitochondrial membrane protein (APO2.7) were analyzed by flow cytometry. The results showed that SNP induced HL-60 cell apoptosis in a dosage- and time-dependent manner. After exposure to SNP at the concentration of 1.0 mmol/L for 48 hours, the percentage of apoptosis HL-60 was (42.2 +/- 3.5)% for subG1 and (52.5 +/- 7.6)% for TUNEL respectively, and they are significantly higher than those in control and potassium ferricyanide (PFC) groups as same concentration. During the apoptosis process, it showed a decrease of Bcl-2 protein and an increase of Bax protein and mitochondrial membrane protein in HL-60 cell, proteins of Bcl-2, Bax and mitochondrial membrane were expressed in a dosage- and time-dependent manner too. In conclusion, during the process of SNP induced apoptosis in HL-60 cell, the expression of mitochondrial membrane protein was increased, Bcl-2 and Bax proteins may be important regulators.