Effect of prostaglandin E1 on DNA synthesis in vascular smooth muscle cells

The effect of prostaglandin E1 (PGE1) on DNA synthesis was determined using cultured vascular smooth muscle cells. It was found that when PGE1 was added to synchronous, quiescent (growth-arrested) cells, it enhanced DNA synthesis. This was in contrast to the effects of PGE1 on asynchronous, cycling (growing) cells. In these cells, when PGE1 was added, it functioned as an antiproliferative agent. In both cases the effects of PGE1 could be mimicked by 6 alpha-carbaprostacyclin (stable prostacyclin analogue) or by 8-bromo adenosine 3',5'-cyclic monophosphate [a permeable adenosine 3',5'-cyclic monophosphate (cAMP) analogue]. In addition PGE1 was shown to cause an elevation in cellular cAMP levels. On the basis of these studies it is hypothesized that the ultimate effect of addition of PGE1 to vascular smooth muscle cells is dependent on the phase of the cell cycle in which it is added.