Adenosine 3',5'-cyclic monophosphate (cAMP) inhibits phorbol ester-induced growth of an IL-2-dependent T cell line.

We previously established a human T cell line, TPA-Mat, which can proliferate in response to not only interleukin-2 (IL-2), but also phorbol esters such as 12-O-tetradecanoylphorbol-13-acetate (TPA) and phorbol-12,13-dibutyrate (PDBu). The present study demonstrated that the PDBu-dependent growth of TPA-Mat cells was inhibited up to 90% by adenosine 3',5'-cyclic monophosphate (cAMP] raising agents such as forskolin, cholera toxin and 1-methyl-3-isobutyl-xanthine, and cAMP analogues, whereas the IL-2-stimulated TPA-Mat growth was slightly inhibited. These findings suggest that the signal transduction pathway of PDBu-induced growth, which should involve activation of protein kinase C, is sensitive to cAMP, and that it cannot be exactly identical to the signal transduction pathway of Il-2-induced growth in TPA-Mat cells.