| Abstract: | The inhibition of cell replication in two human carcinoma cell lines by various cyclic AMP analogs was explored. In all instances, the addition of the cyclic nucleotide phosphodiesterase inhibitor 1-methyl-3-isoburylxanthine resulted in synergistic growth inhibition by the analogs. A correlation was found between an analog's ability to inhibit growth and its ability to activate protein kinase. A differential effect of the breakdown product 8-bromo-AMP (8-BrAMP) on cell replication in the two cell lines was observed; i.e., one cell type was extremely sensitive to inhibition by 8-BrAMP and the growth inhibition could not be reversed by uridine, whereas the other cell type was less sensitive to 8-BrAMP and the growth inhibition was significantly reversed by uridine. |
