Proadrenomedullin NH 2-terminal 20 peptide (PAMP) and adrenomedullin bind to teratocarcinoma cells☆

Abstract

Proadrenomedullin NH 2-terminal 20 peptide (PAMP) and adrenomedullin (ADM) bind to teratocarcinoma cells. The effects of PAMP and ADM on teratocarcinoma cells were investigated. 125I-PAMP bound to PA1 cells with moderate affinity ( K d = 110 nM) to a single class of sites ( B max = 110 000/cell). Specific 125I-PAMP binding was inhibited by PAMP (IC 50 of 100 nM) but not ADM, calcitonin gene-related peptide (CGRP), or amylin. Specific 125I-ADM binding was inhibited with high affinity by ADM, CGRP, and CGRP(8–37) (IC 50 values of 10, 10, and 15 nM respectively) but not PAMP or amylin. ADM elevated cAMP (ED 50 value of 100 nM), whereas PAMP had no effect on basal cAMP but inhibited the increase in cAMP caused by 10 nM ADM. Also, the increase in cAMP caused by ADM was inhibited CGRP(8–37), suggesting that ADM is binding to CGRP receptors. ADM (100 nM) stimulated transiently c-fos mRNA, whereas PAMP (1000 nM) had little effect; however, PAMP inhibited the increase in c-fos mRNA caused by ADM. ADM stimulated [ 3H]thymidine uptake into PA1 cells, whereas PAMP inhibited the increase in thymidine uptake caused by ADM. These results indicate that ADM and PAMP are both biologically active in teratocarcinoma cells.