OBJECTIVETo investigate the effect of AMPK agonist 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) on proliferation, differentiation and apoptosis of U937 cells and explore its possible mechanism.

METHODSU937 cells were cultured with different concentrations of AICAR for 24 h and 48 h. Cell proliferation was evaluated. Cell growth curve was analyzed by CCK-8; cell apoptosis was analyzed by cell morphology, Annexin V/7-AAD double labeling. The differentiation of U937 cells was evaluated by expression of CD11b. The Bcl-xL, Bax, Bim, caspase-3 mRNA expressions of U937 cells were determined by real time PCR.

RESULTSAICAR significantly inhibited the growth of U937 cells in a time-and dose-dependent manner, with a 24 h IC50 value of 1.1 mmol/L and 48 h of 0.9 mmol/L. 1.0 mmol/L AICAR didn't induce differentiation of U937 cells with the increase of CD11b expression for 24 h (P > 0.05). The U937 cells apoptosis was confirmed by cell morphology and Annexin V/7-AAD labeling. AICAR induced apoptosis of U937 cells and the apoptosis rate was (6.81 ± 1.16)% at 1 mmol/L AICAR higher than control group (2.74 ± 0.32)% without AICAR for 24 h treatment (P < 0.05). The real time PCR assay revealed that as compared with control group, the expression of Bim and caspase-3 mRNA were increased, while Bcl-xL and Bax were unchanged on the AICAR treatment.

CONCLUSIONAICAR can effectively inhibit proliferation and induce apoptosis of U937 cells. However, it has no significant effect on differentiation of U937 cells. The mechanism may be related with up-regulating Bim and Caspase-3.