[Mechanism for clofarabine inducing autophagic death of acute myelocytic leukemia cell U937]

To explore the mechanism of autophagic death of acute myelocytic leukemia cell U937 induced by clofarabine, the MTT bioassay was used to analyze the growth inhibitory effect and half inhibition concentration on U937 incubated in vitro with different concentrations of clofarabine for 24 and 48 hours, and the flow cytometry was used to detect the autophagy rate of U937. The expression of Beclin 1 in U937 treated by clofarabine for 48h was measured by Western blot. The results indicated that when U937 cells were treated with 0.01 µmol/L and 0.15 µmol/L clofarabine for 48 hours, the proliferation inhibition rate was 46.92% ± 4.24% and 86.10% ± 1.16%, and the half inhibition concentration of clofarabine was 0.022 µmol/L. With 0.01 µmol/L and 0.1 µmol/L clofarabine on U937 for 48 hours, the autophagy rate was 11.0033% ± 1.4387% and 59.4133% ± 3.5409%, and increased in dose-dependent manner (r = 0.99). Meanwhile the Beclin 1 was upregulated along with increase of clofarabine concentration, as compared with control group, the difference was statistically significant (P < 0.05). It is concluded that the different concentrations of clofarabine can significantly inhibit the proliferation of U937 in dose-dependent manner, and the mechanism of autophagic cell death in U937 may be associated with the upregulation of Beclin 1 expression.