Regulation of rat placental lactogen (rPL)-II secretion: cAMP inhibits rPL-II secretion in vitro.
We examined whether epidermal growth factor (EGF), interleukin (IL)-1, IL-6 and cAMP analogs, which regulate mouse placental lactogen II secretion, affect rat placental lactogen (rPL)-II secretion using a rat choriocarcinoma cell line, Rcho-1. EGF, IL-1 and IL-6 did not affect rPL-II secretion, but 8-bromo-cAMP and forskolin inhibited rPL-II secretion by the 8th day of culture. The effects were dose dependent and the lowest concentrations of 8-bromo-cAMP and forskolin that significantly inhibited rPL-II secretion were 125 and 5 mumol/l, respectively. Cholera toxin also inhibited rPL-II secretion. The reverse hemolytic plaque assay for rPL-II indicated that the cells releasing rPL-II in the culture were giant cells and that 8-bromo-cAMP decreased the number of rPL-II-releasing cells. Western blot analysis of rPL-II yielded a single band at approximately 24.5 K, and 8-bromo-cAMP treatment significantly reduced the band intensity. Northern blot analysis of rPL-II indicated that 8-bromo-cAMP also reduced rPL-II gene expression. These findings suggest that the increase of intracellular cAMP accumulation results in inhibition of rPL-II secretion by decreasing rPL-II gene expression and inhibiting giant cell differentiation.
Yamaguchi
M
M
Department of Obstetrics and Gynecology, Osaka University Medical School, Japan.
Kawai
M
M
Kishi
K
K
Miyake
A
A
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D002772:Cholera Toxin / Q000494:pharmacology; D002822:Choriocarcinoma / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000494:pharmacology*; D004815:Epidermal Growth Factor / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D015850:Interleukin-6 / Q000494:pharmacology; D010928:Placental Lactogen / Q000378:metabolism*; D051381:Rats; D014407:Tumor Cells, Cultured
D007375:Interleukin-1; D015850:Interleukin-6; C062303:placental lactogen II; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D004815:Epidermal Growth Factor; D002772:Cholera Toxin; D010928:Placental Lactogen; D000242:Cyclic AMP