Effects of 17β-estradiol on calcitonin and calcitonin-gene-related peptide secretions and contents in a murine medullary thyroid carcinoma C-cell line (CA-77)

Abstract

Summary ― The effect of 17!-estradiol on calcitonin (CT) and calcitonin-gene-related peptide (CGRP) secretions in the murine CA-77 C cell line was studied after 1, 3, 5 and 6 d of treatment. The release of both CT and CGRP significantly increased 1, 3, 5 and 6 d after addition of 0.1 Ilmol/l estradiol alone to the culture medium. The C cell content of both peptides also increased after 6 d of treatment with the same dose of estrogen. The enhanced CT and CGRP secretions induced by 17(3-estradiol were not inhibited by the simultaneous addition of 5 wmol/I of all-trans-retinoic acid. Dexamethasone alone increased the release of both peptides within 6 d. However, when cells were treated simultaneously with estradiol and 1 pmol/I dexamethasone, the addition of retinoic acid blunted both the CT and CGRP secretions induced by dexamethasone. These results showed that the positive effects of 17(3-estradiol on both CT and CGRP secretions were modulated by dexamethasone and retinoic acid.CT secretion / CGRP secretion / CA-77 C cell / 17(3-estradiol / dexamethasone / retinoic acid Résumé ― Le 17p-oestradiol à la dose de 100 nmolll augmente la sécrétion et le contenu cellulaire de CT et de CGRP par la lignée de cellules C (CA-77) d'origine murine. Les effets de /'œsfrad/o/ sur la libération de CT et de CGRP dans le milieu de culture sont observés 1, 3, 5 et 6 j après addition du stéroïde. Le contenu cellulaire en hormones est également légèrement augmenté sous cestradiol. L'acide rétinoi'que all-trans 5 wmolll ne diminue la sécrétion des 2 peptides qu'au bout de 6 j, alors que la dexaméthasone 1 pmolll, seule, stimule la sécrétion de CT et CGRP tout au long du traitement (de 1 à 6 j). Si l'acide rétinoïque n affecte pas le contenu cellulaire en CT et CGRP, la dexaméthasone, en revanche, l'augmente. Le co-traitement par l'c!stradiol et l'acide rétinoique n'inhibe pas l'effet du sté-roïde sur la sécrétion de CT et de CGRP. Dans le cas d'un co-traitement par la dexaméthasone et l'oestradiol, un effet additif n'est observé qu'après 3 j de traitement. Le traitement simultané des cellules C par les 3 molécules montre à chaque fois (1, 3, 5 et

Decrease in CGRP and CT levels either contained in or released by CA-77 C cells after combined treatments with 1,25-dihydroxyvitamin D 3 analogues and 9-cis retinoic acid

“…Co-treatment of CA-77 C cells by dexamethasone and 9-cis retinoic acid reduced the usual increase in the release of both CT (Lamari et al, 1994). A slight decrease in the release of both hormones in the culture medium was observed with a lower dose (5 pM) after 6 days of exposure to all-tran.s retinoic acid (Lamari et al, 1995). The present results demonstrated that CA-77 cells are also sensitive to 9-cis retinoic acid since the release of both CT and CGRP were decreased with a half-effective dose of 10 nM.…”

“…Intra-assay variations for the CT RIA were 5% and inter-assay variations were 10%. For the CGRP, the RIA used has been described previously (Maubras et al, 1993;Lamari et al, 1995 The bound to free fractions were separated by adding 0.15 mL of dextran charcoal suspension buffer to each assay tube (0.5 mL). After centrifugation at 2 000 g for 20 min, the supernatant was discarded.…”

Expression of glucagon‐like peptide 1 receptor in a murine C cell line Regulation of calcitonin gene by glucagon‐like peptide 1

“…Intra-assay variations for the CT RIA were 5°/,, and inter-assay variations were 10%. For the CGRP RIA already described [14,15], we have used synthetic human CGRP (Sigma) as standard, a sheep antibody raised against synthetic human CGRP diluted 1 : 100 000, and [125I]iodohistidyl human CGRP from Amersham (Les Ulis, France). The tubes were preincubated for 4 days at 4°C and then incubated for 3 days at 4°C in the presence of labeled CGRP.…”