Action of calcitonin gene-related peptide at the calcitonin receptor of the T47D cell line

Abstract

Some effects of calcitonin (CT) can also be produced by calcitonin gene-related peptide (CGRP), an alternative product of the calcitonin gene. This might be mediated by interaction of CGRP at the CT-receptor site. The human breast cancer cell line T47D possesses well characterized CT-receptors (KD = 2.3 x 10(-10) M for 125I salmon CT). 50% inhibition of 125I-sCT binding was achieved with 10(-9) M sCT, 5 x 10(-6) M rat CGRP and 10(-5) M human CGRP. Half maximal cAMP production in T47D cells was seen with 6 x 10(-10) M sCT, 5 x 10(-6) M rCGRP and 10(-5) M hCGRP. Binding and displacement capacity as well as the biological activity of CT and CGRP seems to correlate well. These findings suggest that CGRP in pharmacological doses acts via the CT-receptor. This could be explained by the homology and conformational similarities between CT and CGRP.