CYCLIC ADENOSINE-MONOPHOSPHATE PROMOTES CELL-SURVIVAL AND RETARDS APOPTOSIS IN A FACTOR-DEPENDENT BONE-MARROW-DERIVED CELL-LINE

Hemopoietic growth factors promote cell survival, proliferation and di fferentiation, but whether these processes, which often occur in conce rt, are mediated through the same or different receptor signaling mech anisms is not known. Using the bone marrow-derived IL-3-dependent cell line, 32D, we show that dibutyryl cyclic adenosine monophosphate (dbc AMP) retards the rapid loss of viable cells seen in the absence of IL- 3. This effect is shown to be concentration-dependent and detectable w ithin 16 hours of culture and is not associated with cell differentiat ion. At earlier times (2 to 7 hours), when no significant changes in c ell numbers were observed, dbcAMP stimulated the reduction of dimethyl thiazoldiphenyl tetrazolium bromide (MTT), and this effect was indisti nguishable from that seen with IL-3. In contrast, control cells depriv ed of growth factor showed a decline in MTT response over this period. The effect of dbcAMP in maintaining cell viability and MTT responsive ness was associated with a concentration-dependent inhibition of H-3-t hymidine incorporation into DNA, and retardation of the intranucleosom al cleavage of DNA that is associated with apoptosis. These results su ggest that in 32D cells, cAMP can act to promote cell survival and ret ard apoptosis, quite independently of cell proliferation, by stimulati ng the activity of mitochondrial enzymes involved in MTT reduction.