THE HUMAN GALANIN RECEPTOR - LIGAND-BINDING AND FUNCTIONAL-CHARACTERISTICS IN THE BOWES MELANOMA CELL-LINE

The human galanin receptor has been characterized pharmacologically from the Bowes melanoma cell line. Using porcine [I-125]galanin as the radioligand, a single population of non-interacting high-affinity binding sites (K-D = 0.05 +/- 0.01 nM; B-max = 135 +/- 7 fmol/mg protein) was demonstrated. Human galanin peptide competitively inhibited the specific binding of [I-125]galanin (IC50 = 0.35 +/- 0.13 nM) and decreased the forskolin-stimulated cAMP production (EC(50) = 0.46 +/- 0.05 nM) with a maximal inhibition of 63 +/- 2% at 10(-7) M. Rat and porcine galanin peptides and the chimeric peptides M15, M35, M32, M40 and C7 also dose-dependently inhibited the forskolin-stimulated cAMP production, while the fragment porcine galanin-(3-29) and [D-Trp(2)]galanin were found to be inactive. The specific binding of [I-125]galanin was decreased in a dose-dependent manner by GTP and the cAMP response was inhibited by the pertussis toxin, suggesting the activation of a G-protein dependent process. The Bowes cell line thus appears to be a relevant tool for the study of human galanin receptor.