[Retinoic acid intensifies the suppression of the proliferation of K562 cells by phorbol ester].

The effect of forbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA) on the growth of cultured human chronic promyelocytic leukemia (K562) cells has been studied using cells growing in a medium consisting of RPMI 1640 supplemented with 10% fetal serum and with or without retinoic acid. All the used concentrations of TPA (100.0, 10.0, 1.0 and 0.1 ng/ml) cause the expected inhibition of proliferation of these cells. Moreover, a block of proliferation of K562 cells became stronger after cotreatment with TPA and retinoic acid, although this acid itself did not have any effect on proliferation and differentiation of K562 cells.