ucn-1028-c and Pheochromocytoma

Our purpose was to determine the role of protein kinases in the mediation of the stimulatory effects of lead on catecholamine secretion. Pheochromocytoma cells were incubated for 90 minutes with W-7 (calmodulin antagonist), calphostin C (protein kinase C inhibitor), Sp-cAMPS (cAMP agonist), Rp-cAMPS (cAMP antagonist), forskolin (activator of adenylyl cyclase), or lead nitrate. Catecholamines were measured by liquid chromatography. Lead had a stimulatory effect on catecholamine secretion, whereas W-7 was inhibitory. In the presence of both lead and W-7, the response was markedly decreased compared to that seen with lead alone. Calphostin C suppressed the secretion of catecholamines; however, in the presence of lead and calphostin C, the secretion was similar to that seen with lead alone. Compared to control, Sp-cAMPS was stimulatory. Co-incubation of Sp-cAMPS and lead had a slight synergistic effect. Rp-cAMPS decreased catecholamine secretion, but co-incubation of Rp-cAMPS and lead resulted in a slight reduction compared to lead alone. Forskolin markedly increased the secretion of catecholamines, and co-incubation of lead and forskolin resulted in a synergistic increase. In the absence of calcium, lead had no effect. We conclude that lead stimulates catecholamine secretion by acting through the calcium/calmodulin-dependent protein kinase II system and not through the protein kinase C or protein kinase A system, and requires the presence of calcium for its action.

Topics: Adenylyl Cyclases; Animals; Calmodulin; Catecholamines; Colforsin; Cyclic AMP; Enzyme Activation; Enzyme Inhibitors; Lead; Models, Biological; Naphthalenes; Nitrates; Pheochromocytoma; Protein Kinase C; Rats; Sulfonamides; Thionucleotides; Tumor Cells, Cultured

Topics: Adenylyl Cyclases; Adrenal Gland Neoplasms; Animals; Chloramphenicol O-Acetyltransferase; Colforsin; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Enzyme Activation; Gene Expression; Isoquinolines; Kinetics; Naphthalenes; Neuropeptide Y; PC12 Cells; Pheochromocytoma; Polycyclic Compounds; Promoter Regions, Genetic; Protein Kinase C; Rats; Sulfonamides; Transcription, Genetic

Exposure of PC12-VG cells to an extremely low frequency magnetic field (ELFMF) enhanced the beta-galactosidase gene expression stimulated by treatment of the cells with forskolin. The enhancing effect of the ELFMF was inhibited by treatment of the cells with a specific inhibitor of PKC, calphostin C, as well as with the Ca2+ entry blockers nifedipin and dantrolen. Enhancement appeared within the first hour of a 4h forskolin treatment when the ELFMF was given at different times during culture. We speculate that exposure of PC12-VG cells to an ELFMF during the early response to forskolin treatment affects cell signal transduction, resulting in enhanced gene expression.

Topics: Adrenal Gland Neoplasms; Animals; beta-Galactosidase; Colforsin; Dantrolene; Escherichia coli; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Neoplastic; Humans; Kinetics; Magnetics; Naphthalenes; Nifedipine; PC12 Cells; Pheochromocytoma; Promoter Regions, Genetic; Protein Kinase C; Rats; Recombinant Proteins; Tetradecanoylphorbol Acetate; Transfection; Vasoactive Intestinal Peptide