PRODUCTION OF BIOACTIVE SALMON-CALCITONIN FROM THE NONENDOCRINE CELL-LINES COS-7 AND CHO

To produce bioactive salmon calcitonin from the conventional nonendocr ine cell lines, COS-7 and CHO, we devised a salmon calcitonin expressi on Vector by combining the amino-terminus of human calcitonin precurso r with a salmon calcitonin sequence, inserting the efficient furin-cle avable processing sequence Arg-X-Arg-X-Lys-Arg before salmon calcitoni n, and deleting the carboxyl-terminal extension peptide. This chimeric calcitonin precursor terminates at glycine to easily receive an amida tion reaction. COS-7 and CHO produced a high level of bioactive calcit onin by the resorption pit formation assay. Although amidating activit y is highly expressed in CHO, but only a little in COS-7 cells, both c ells produced a similar level of bioactive calcitonin. Thus, the engin eered salmon calcitonin expression Vector enables nonendocrine cells e ven with low amidation activity to produce bioactive calcitonin. (C) 1 997 Elsevier Science Inc.