Elevation of cyclic adenosine 3', 5'-monophosphate potentiates activation of mitogen-activated protein kinase by growth factors in LNCaP prostate cancer cells

• Published in: Cancer research (Chicago, Ill.) Ill.), 1999, Vol.59 (1), p.213-218
• Main Authors: TAOSHENG CHEN, CHO, R. W, STORK, P. J. S, WEBER, M. J
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Blood Proteins - pharmacology; Calcium-Calmodulin-Dependent Protein Kinases - metabolism; Cyclic AMP - metabolism; Enzyme Activation - drug effects; Epidermal Growth Factor - pharmacology; Humans; Interleukin-6 - pharmacology; Male; Medical sciences; Nephrology. Urinary tract diseases; Prostatic Neoplasms - metabolism; Signal Transduction - drug effects; Tumor Cells, Cultured; Tumors of the urinary system; Urinary tract. Prostate gland
• ISSN: 0008-5472; 1538-7445

Prostate cells are simultaneously exposed to a variety of peptide growth factors and neuropeptides that elevate cAMP. Both the growth factors and cAMP have large effects on the growth, differentiation, and movement of many cell types. Because mitogen-activated protein kinase (MAPK) is central to these effects, we analyzed the ways in which these agonists interact in regulating MAPK in prostate cancer cells. We show that, in LNCaP prostate cancer cells, elevation of intracellular cAMP can potentiate the ability of epidermal growth factor (EGF), interleukin 6, and serum to activate MAPK and that this potentiation depends on protein kinase A and Rap1. The response to cAMP is different in the androgen-independent prostate cancer cell line PC-3, where elevation of cAMP slightly inhibits MAPK activation by EGF. We also show that treatment of LNCaP with the calcium ionophore A23187 or the phorbol ester phorbol 12-myristate 13-acetate activates MAPK, but the activation of MAPK by these agonists is inhibited rather than potentiated by increasing cAMP. Finally, we show that phorbol 12-myristate 13-acetate and interleukin 6 can potentiate the signaling activity of EGF. We conclude that neuroendocrine factors that elevate cAMP sensitize LNCaP prostate cancer cells to signaling by peptide growth factors and that low levels of mixtures of growth factors can activate intracellular signaling to a greater degree than would be predicted from the activity of the individual agonists.