Effect of medroxyprogesterone acetate and of some antiinflammatory agents on mouse erythroleukemia cell differentiation.

The effects of medroxyprogesterone acetate (MPA) on differentiation were examined using mouse erythroleukemia (MEL) cells and compared with those of antiinflammatory agents. MPA at low doses (10(-6) - 10(-7)M) induced 10-15% cells to differentiate, whereas high doses (10(-4) - 10(-5)M) caused a 30% inhibition of dimethylsulfoxide (DMSO)-induced differentiation. Dexamethasone (10(-4) - 10(-8)M), a steroid antiinflammatory agent, significantly inhibited (77-70%) DMSO-induced differentiation, whereas indomethacin, aspirin, flurbiprofen and BW755c (non steroid antiinflammatory agents) at the same concentrations had no effect. If added 24 h before DMSO, the inhibitory effects of MPA and dexamethasone increased to 65% and 95%, respectively, whereas indomethacin (10(-5)M) caused only a 30% inhibition and the other drugs were inactive. None of these antiinflammatory agents affected differentiation when used without DMSO. MPA and dexamethasone inhibitory effects on DMSO-induced differentiation did not seem to be mediated through the inhibition of the synthesis of prostaglandins, since non-steroid prostaglandin inhibitors were slightly active only when added 24 h before DMSO.