Human glioblastoma cell lines have neuropeptide receptors for bombesin/gastrin-releasing peptide.
Bombesin/gastrin-releasing peptide receptors were characterized in human glioblastoma cell lines. [125I]Gastrin-releasing peptide or ([125I]Tyr4)bombesin bound with high affinity to these cell lines. Binding to cell line U-118 was time dependent, reversible, and specific. ([125I]Tyr4)Bombesin bound with high affinity (Kd = 1.6 nM) to a single class of sites (Bmax = 30,000/cell). The C-terminal of bombesin- or gastrin-releasing peptide was essential for high-affinity binding. Bombesin- or gastrin-releasing peptide elevated the cytosolic Ca2+ levels in a dose-dependent manner. Because gastrin-releasing peptide, but not gastrin-releasing peptide, increased the cytosolic Ca2+ levels, the C-terminal but not the N-terminal of GRP is essential for biological activity. These data indicate that biologically active bombesin receptors are present in human glioblastoma cell lines.