Effect of synthetic retinoids and tyrosine kinase inhibitors on the granulocytic differentiation and growth of NB4 cells.
NB4 cells were seeded at an initial concentration of 2 × 105/mL and treated for 4 days (A and B) or 3 days (C and D) with the indicated compounds. (A) NBT-reducing activity in NB4 cells treated with the indicated concentrations of the RARα agonist AM580 in the absence (○) or presence of STI571 (●, 5 × 10−6 M). (B) NBT-reducing activity in cells treated with vehicle (control), STI571 (5 × 10−6 M), the RXR agonist CD2915 (10−6 M), 8-CPT-cAMP (1 × 10−4 M; cAMP), ATRA (10−7 M), and the indicated combinations. (C) and (D) NBT-reducing activity and growth of cells treated with vehicle (control), STI571 (5 × 10−6M), ATRA (10−7 M), the tyrosine kinase inhibitors AG957 (1 × 10−6 M), NSC68 410 (1 × 10−6 M), and NSC676448 (1 × 10−6 M) or the indicated combinations. Results are the mean ± SD of 3 separate culture dishes and are representative of at least 2 independent experiments. *, significantly higher or lower than the corresponding group treated with medium alone (P < .01 according to the Studentt test). °, significantly higher than the sum of the effects observed in the corresponding STI571- and ATRA-treated groups, following 2-way analysis of variance and measurement of the F of interaction (P < .01 according to Tukey test).
