Synthesis of α- and β-calcitonin gene-related peptide by a human pheochromocytoma

One histologically verified human pheochromocytoma, out of a total of nine such tumors examined, contained calcitonin gene-related peptide (CGRP)-like immunoreactivity (151 pmol/g wet weight) that was localized to a scattered population of tumor cells. The immunoreactivity was resolved by high performance ion-exchange chromatography into two components with the retention times of human α-CGRP and β-CGRP in the approximate ration 1:2. No pheochromocytoma in this series contained calcitonin-like immunoreactivity. In contrast, two neuroendocrine tumors of the pancreas contained calcitonin-like immunoreactivity (190 pmol/g and 125 pmol/g) but no CGRP-like immunoreactivity was detected. These results indicate a degree of tissue selectivity in the processing of the primary transcripts of the calcitonin/CGRP genes in human tumors.