Bombesin in human neuroendocrine (NE) neoplasms

Bombesin is a 14 amino acid peptide isolated from amphibian skin which was found to have stimulatory effects upon gastric and pancreatic secretions, release of gastrointestinal Hormones, gallbladder contraction and bronchoconstriction. It is present in amphibian gastric endocrine cells, avian proventriculus endocrine cells and avian brain. In mammals it is present mainly in nerve cells and fibers. The only mammalian endocrine cell shown to date to have bombesin is the P-cell in fetal lung. Bombesin is also found in mammalian brain, with its highest concentration in the hypothalamus. We examined several groups of human neuroendocrine neoplasms for the presence of bombesin by immunohistochemistry. Our findings indicate that bombesin is present 68% of bronchial carcinoids, 65% of pulmonary neuroendocrine carcinomas, 62% of neuroendocrine carcinomas of the skin, 5-10% of pheochromocytomas and extraadrenal paragangliomas and 35% of gastrointestinal carcinoids and neuroendocrine carcinomas. Parallel studies in a wide variety of non neuroendocrine neoplasms failed to reveal the presence of bombesin. We conclude that bombesin is a highly specific marker of neuroendocrine differentiation and thus a valuable tumor marker. Furthermore, its specificity compares favorably with another neuroendocrine marker, neuron specific Enolase, an Enzyme thought to be present only in neural tissues and neuroendocrine cells but recently found in non neural human tissues and non neuroendocrine neoplasms.