Biosynthesis and storage of catecholamines in pheochromocytoma and neuroblastoma cells.

Abstract

Abstract The catecholamine contents of tumors from 11 patients with pheochromocytoma and 4 patients with neuroblastoma were estimated spectrofluorophotometrically and compared with the amounts of catecholamines and their metabolites excreted in the urine of these patients. Pheochromocytomas were found to contain much catecholamine and in correspondence with this, increased excretion of norepinephrine or epinephrine, and their metabolites, metanephrines, and vanillyl mandelic acid, were observed in patients with these tumors. Neuroblastomas contained little catecholamine, but patients with these tumors excreted increased amounts of dopamine, homovanillic acid, and vanillyl mandelic acid. Therefore, the ratio of norepinephrine plus epinephrine to vanillyl mandelic acid in the urine of patients with neuroblastoma seemed to be less than that in urine of patients with pheochromocytoma. Electron microscopy showed many dense-cored granules containing catecholamine in pheochromocytomas, but few in neuroblastomas. Tyrosine hydroxylase, dopa decarboxylase, and dopamine β-hydroxylase activities were found in both types of tumors. These findings strongly suggest that neuroblastomas lack a catecholamine storing mechanism so that catecholamine is released from the tumor cells and inactivated soon after its formation. This may be one reason why patients with neuroblastomas exhibit very few symptoms associated with stimulation of the sympathetic nervous system.