Objective: To investigate the effects of arsenic trioxide (ATO) on the expressions of vascular endothelial growth factor (VEGF) and P-glycoprotein (P-gp) in K562/A02 cells and to explore the correlation between VEGF and P-gp.Methods: The inhibition rate of K562/A02 cell proliferation was detected by using methyl thiazolyl tetrazolium assay (MTT); the level of VEGF was detected by enzyme-linked immunosorbent assay (ELISA) and the expression rate of P-gp was determined by flow cytometry (FCM).Results: 0.05 μmol/L ATO had no influences on the cell proliferation and the expression of VEGF in K562/A02 cells; 0.4 and 3.2 μmol/L ATO could significantly inhibit the K562/A02 cell proliferation and down-regulate the expression of VEGF in K562/A02 cells (P<0.05). The expression of P-gp did not changed after being exposed to 0.05 and 0.4 μmol/L ATO for 24, 48 and 72 hours (P>0.05). 3.2 μmol/L ATO could remarkably reduce the expression of P-gp in K562/A02 cells after 48- and 72-hour incubation with ATO (P<0.05).Conclusions: The down-regulation of P-gp and VEGF after being exposed to ATO probably contributes to the reversion of multidrug resistance in K562/A02 cells. The level of VEGF may be related to the expression rate of P-gp in K562/A02 cells.

Key words: vascular endothelium, endothelial growth factors, arsenic compounds, leukemia