VITAMIN-D-3 EFFECTS ON BASAL AND CAMP MODULATED EXPRESSION OF CHOLECYSTOKININ AND SOMATOSTATIN GENES IN A RAT MEDULLARY-THYROID CARCINOMA CELL-LINE [CA-77]

The regulation of cholecystokinin and somatostatin expression by vitamin D and cyclic AMP in the rat medullary thyroid carcinoma cell line CA-77 was investigated. Treatment with 100 nmol/l vitamin D did not affect cholecystokinin mRNA and peptide concentrations significantly; somatostatin mRNA level increased 6 times and the somatostatin peptide concentration increased 2-fold after 5 days of drug treatment. Under the same experimental conditions cyclic AMP increased cholecystokinin mRNA level 4.5 times and the cellular cholecystokinin-peptide concentration 2-fold; somatostatin mRNA and peptide concentrations were not significantly changed. Cyclic AMP stimulated peptide secretion from the cells were not affected by vitamin D, but cyclic AMP mediated increase in CCK peptide concentration was significantly inhibited by vitamin D (p < 0.05).