Immunohistological Localization of Growth Hormone-Releasing Hormone in Human Tumors*

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Abstract
Two forms of GH-releasing factor (GHRH), which play a role in the regulation of GH secretion, have been isolated from pancreatic endocrine tumors in two patients with acromegaly. We examined formalin-fixed, paraffin-embedded human tissues from autopsies and surgical specimens for the presence of human pancreatic GHRH-40 using the avidin-biotin-peroxidase complex technique to assess the prevalence of tumors containing GHRH, to define their primary sites and cellular derivations, and to correlate clinical and pathological features. Immunopositivity was demonstrated in 4 of 24 pancreatic endocrine tumors, 1 of 5 bronchial and 2 of 15 gut carcinoids, 1 of 2 thymic carcinoids, 2 of 20 medullary carcinomas of the thyroid, 1 of 12 pheochromocytomas, and 5 of 20 small cell carcinomas of the lung. Of the GHRH-containing tumors, only 2 of the pancreatic endocrine tumors and the bronchial carcinoid were associated with acromegaly. No GHRH was found in 35 tumors derived from cells that are not known to produce peptide hormones. Immunoreactivity was not detected in the nontumor-ous tissues from which GHRH-containing tumors were derived. It can be concluded that GHRH may be found in a variety of tumors arising from and composed of peptide hormone-producing endocrine cells. The significance of immunoreactive GHRH detected in tumors unassociated with clinical evidence of acromegaly remains to be established.