Specific binding sites for epidermal growth factor and its effect on human chorionic gonadotrophin secretion by cultured tumour cell lines: comparison between trophoblastic and non-trophoblastic cells.
Using human trophoblastic (SCH) and nontrophoblastic (HeLa S3) tumour cell lines, specific binding sites for epidermal growth factor (EGF), a potent stimulator of growth in many tissues, and its effect on secretion of human chorionic gonadotrophin (hCG) and/or its subunits were compared between these two tumour cells. Both SCH and HeLa S3 cells possessed two populations of specific binding sites for 125I-labelled EGF: the high affinity (Kd approximately 10(-10) M) and the low affinity (Kd approximately 7 x 10(-10) M) system. Tetradecanoyl phorbol acetate (TPA), a tumour promotor, showed a potent competitor of labelled tracer binding to its receptor sites in both cell lines. EGF stimulated both hCG-alpha and hCG and/or hCG-beta secretion in a dose-responsive manner from SCH cells, whereas it had no effect on hCG-alpha secretion from HeLa S3 cells. In contrast, dibutyryl cyclic AMP plus theophylline, a phosphodiesterase inhibitor, enhanced hCG-alpha secretion from both cells, while TPA had no effect in either cells. These data suggest that EGF may play a physiological role in hCG secretion from trophoblastic tissues and that the mechanism by which hCG and/or its subunits are secreted may differ between trophoblastic and non-trophoblastic tumour cells.
D003994:Bucladesine / Q000494:pharmacology; D002460:Cell Line; D006063:Chorionic Gonadotropin / Q000378:metabolism*; D004815:Epidermal Growth Factor / Q000378:metabolism* / Q000494:pharmacology; D066246:ErbB Receptors; D005260:Female; D006367:HeLa Cells / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D011247:Pregnancy; D011956:Receptors, Cell Surface / Q000378:metabolism*; D013806:Theophylline / Q000494:pharmacology; D014328:Trophoblastic Neoplasms / Q000378:metabolism*; D014594:Uterine Neoplasms / Q000378:metabolism*
D006063:Chorionic Gonadotropin; D011956:Receptors, Cell Surface; D004815:Epidermal Growth Factor; D003994:Bucladesine; D013806:Theophylline; D066246:ErbB Receptors