Figure 4. Targeted inhibition of RalA attenuates CML malignant progression and sensitizes K562 cells to imatinib treatment.
(A) Inhibition of RalA sensitizes K562 cells to imatinib. K562 cells transfected with control, RalA siRNA or miR-181a were treated with different concentrations of imatinib (0–0.25 μM) for 24 h and the viability of cells was determined by MTT assay. (B) Inhibition of RalA reduces CML cell migration. A total of 6 × 105 K562 cells transfected with control, RalA siRNA or miR-181a were seeded into the upper chambers, counted after 24 h, followed by counting of cell numbers in the lower chambers. (C) Inhibition of RalA reduces CML cell invasion. A total of 3 × 105 cells transfected with control, RalA siRNA, or miR-181a were seeded into the upper chambers coated with Matrigel, stained with hematoxylin and counted after 8 h. (D) Inhibition of RalA reduces K562 cell colony formation. A total of 1000 K562 cells transfected with control, RalA siRNA, or miR-181a were mixed with RPMI-1640 medium containing 0.9% methylcellulose solution and 20% FBS, and seeded onto 24-well plates. Colony numbers were counted after 1 week. Histogram and statistics indicating the relative number of colonies per 1000 plated cells are shown in the lower panel. Statistical significance was assessed by one-way ANOVA (*p < 0.05).