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

The effect of 17 beta-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 mumol/l estradiol alone to the culture medium. The C cell content of both peptides also increased after d of treatment with the same dose of estrogen. The enhanced CT and CGRP secretions induced by 17 beta-estradiol were not inhibited by the simultaneous addition of 5 mumol/l 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 mumol/l 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 beta-estradiol on both CT and CGRP secretions were modulated by dexamethasone and retinoic acid.