Effects of PD98059 and LY294002 on BCR/ABL-induced VEGF gene expression.

(A) Ton.B210-X cells grown in the presence of doxycycline were incubated with MEK inhibitor PD98059 (50 μM), PI3-kinase inhibitor LY294002 (20 μM), dimethyl sulfoxide (DMSO; solvent control), or control medium (control) for 24 hours. After incubation, cells were harvested and subjected to Northern blotting using a VEGF cDNA probe. The β-actin loading control and a densitometric quantification of VEGF mRNA levels (relative to β-actin) are shown below the blot analyses. (B) Primary leukemic peripheral blood cells derived from a patient with chronic-phase BCR/ABL⁺ CML were incubated with PD98059 (10 μM), LY294002 (10 μM), DMSO, or control medium for 12 hours and then subjected to Northern blotting. The β-actin loading control is also shown. (C) Ton.B210-X cells induced to express BCR/ABL by the addition of doxycycline were incubated with PD98059 (50 μM), LY294002 (20 μM), or control medium for 24 hours. Induced and starved Ton.B210-X cells (not expressing BCR/ABL) were examined for VEGF reporter gene activity. Results represent the means ± SD of 3 independent experiments.