Involvement of polyamines in apoptosis. Facts and controversies: effectorsor protectors?

The natural polyamines (putrescine, spermidine and spermine) are ubiquitous low-molecular aliphatic amines that play multifunctional roles in cell gro wth and differentiation Recently, evidence has merging that polyamines are actively involved in cell death. Changes in polyamine homeostasis have been reported during cell death of nerve cells, in programmed cell death of emb ryonic cells and in various in vitro models of apoptosis. Polyamines and ma ny oft heir structural analogs exert cytotoxic effects in vitro as well in vivo. Futhermore, polyamine analogs and inhibitors of the polyamine anaboli c/catabolic pathways modulate processes of cell death in a cell-type specif ic way. Much ambiguity exists in the working mechanisms by which polyamines mediate apoptosis since they have been shown to act as promoting; modulati ng or protective agents in apoptosis. Nevertheless, from the studies review ed here it can be concluded that polyamines are critically involved in cell ular survival which makes them suitable targets for therapeutic interventio n that is specifically directed to cell death pathways.