Involvement of down-regulation-resistant protein kinase C in teleocidin inhibition of cell proliferation and calcium mobilization induced by epidermal growth factor and vasopressin in human hepatoma cells.
Teleocidin, a phorbol ester-type tumor promoter, inhibits cell proliferation and calcium mobilization induced by epidermal growth factor and vasopressin in PLC/PRF/5 hepatoma cells. These inhibitory effects of teleocidin were observed even after a prolonged exposure of the hepatoma cells to this promoter, suggesting the presence of down-regulation-resistant protein kinase C in this hepatoma cell line. Column chromatography of cytosolic fractions showed three separate peaks of protein kinase C activity, two being down-regulation-sensitive while one was down-regulation-resistant. This down-regulation-resistant PKC is suggested to be responsible for the inhibitory effect of teleocidin on cell proliferation and calcium mobilization induced by epidermal growth factor and vasopressin.
Kaneko
Y
Y
First Department of Medicine, University of Tokyo, Faculty of Medicine, Japan.
Tsukamoto
A
A
Kurokawa
K
K
D002118:Calcium / Q000378:metabolism*; D006528:Carcinoma, Hepatocellular; D002452:Cell Count; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D004815:Epidermal Growth Factor / Q000037:antagonists & inhibitors*; D006801:Humans; D008235:Lyngbya Toxins / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014407:Tumor Cells, Cultured / Q000187:drug effects; D014667:Vasopressins / Q000037:antagonists & inhibitors*
D008235:Lyngbya Toxins; D014667:Vasopressins; C022176:teleocidins; D004815:Epidermal Growth Factor; D011493:Protein Kinase C; D002118:Calcium