Bombesin-Like Peptides in Human Endocrine Tumors: Quantitation, Biochemical Characterization, and Secretion

Bombesin-like immunoreactivity (BLI) in 20 human endocrine tumors was studied using an antiserum directed toward the C-terminal region of bombesin. Additionally, plasma BLI was assayed in normal subjects and patients with known BLI-containing tumors. In 7 tumors (medullary carcinoma of the thyroid, n = 2; carcinoid of the lung, n = 3; hepatic carcinoid, n = 1; pheochromocytoma, n = 1), the BLI content ranged from 6–2000 pg/mg wet wt of tissue. Sephadex G-50 gel chromatography of tumor extracts under acid-dissociating conditions revealed 2 peaks of BLI: 1 coeluting with porcine gastrinreleasing peptide (GRP) and 1 with bombesin. Reverse phase ODS silica HPLC analysis of the G-50 peaks using a methanoltrifluoroacetic acid gradient showed that human tumor BLI more closely resembled porcine GRP and its C-terminal fragment GRP-(14–27) than bombesin itself. Partial tryptic digestion of the tumor GRP-like peptide generated a product which, on HPLC, was similar to GRP-(14–27). Elevated plasma BLI was detected in ...