Prostaglandin-induced changes in calcium uptake and cAMP production in osteoblast-like cells: role of protein kinase C.
Phorbol esters were used to evaluate the putative effect of protein kinase C (PKC) activation on prostaglandin E2 (PGE2)-induced increases in calcium uptake and cAMP production in the human osteoblastic osteosarcoma cell line, Saos-2. The cells were pretreated for 15 min with phorbol myristate acetate (PMA) followed by a 5 min incubation with PGE2. Calcium uptake was measured with 45Ca and cAMP by radioimmunoassay. A significant increase in calcium uptake was noted in the PGE-treated cells compared with controls and preincubation with the PMA caused a significant decrease in this response. Preincubation with PMA also inhibited the PGE2-induced increase in cAMP under identical conditions. The effect of PMA on the cAMP response was not influenced by the addition of a phosphodiesterase inhibitor. PMA had no effect on the basal levels of either calcium uptake or cAMP production. Likewise, the inactive phorbol esters, phorbol 12,13-didecanoate (PDD) and 4 alpha-phorbol 12-myristate, 13-acetate (4 alpha), had no effect on either basal levels of these parameters or on the PGE2-induced increases. These results suggest that PKC is involved in the down-regulation of PGE2-induced increases in calcium uptake and cAMP production in the Saos-2 osteoblastic cell line.
Hagel-Bradway
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S
Department of Endodontics, School of Dental Medicine, State University of New York, Buffalo 14214.
Tatakis
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DN
Dziak
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R
D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D000242:Cyclic AMP / Q000096:biosynthesis*; D015232:Dinoprostone / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D006801:Humans; D010006:Osteoblasts / Q000378:metabolism*; D012516:Osteosarcoma / Q000378:metabolism; D010703:Phorbol Esters / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D011863:Radioimmunoassay; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D010703:Phorbol Esters; C008876:phorbol-12,13-didecanoate; D000242:Cyclic AMP; D011493:Protein Kinase C; D015232:Dinoprostone; D013755:Tetradecanoylphorbol Acetate; D002118:Calcium