Effect on proliferation and apoptosis and regulation on nucleoporin Nup88 in acute leukemic cell U937 by gambogic acid

Abstract

Objective: To investigate the effect on proliferation and apoptosis and the regulation on nucleoporin Nup88 in acute leukemic cell U937 by gambogic acid (GA) in vitro. To study the relationship between the effect and the regulation. Methods: The effect of GA on the growth of U937 cells was studied by MTT assay. Apoptosis was detected through Annexin-V FITC/PI double-labeled cytometry and Hoechst 33258 staining. The influence on cell cycle was studied by a propidium iodide method. Both flow cytometry (FCM) and RT-PCR technologies were applied to assessing the expression of Nup88, whereas, the cell localization of Nup88 was determined by using confocal microscopy method. Results: GA presented striking proliferation inhibition, as well as apoptosis induction potency on U937 cells in vitro in a time-and dose-dependent manner. The IC50 value for 24 h was (1. 019±0. 134) mg/L. Moreover, cells treated with GA showed accumulation in G0/G1 phase and reduction in the percentage of cells in S phase. The expression of Nup88 was down-regulated in U937 cells by GA in a dose-dependent manner, and the disposition of Nup88 was also switched from widely dispersed in both nucleus and cytoplasm to situate only at the cytoplasmic side of nuclear rim, occasionally in cytoplasm sporadically. Conclusion: GA exhibits the potent proliferation inhibition, apoptosis induction, and cell-cycle arrest in leukemia cells, which might correspond to the down-regulation of the expression, as well as the disposition, of nucleoporin Nup88.