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.
First Department of Medicine, University of Tokyo, Faculty of Medicine, Japan.
Y
Y
Kaneko
A
A
Tsukamoto
K
K
Kurokawa
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