The pheochromocytomas on the two sides exhibited negative ACTH staining, but the ACTH concentration was markedly higher in the tumor tissue homogenates than in those tumors of another 3 patients with non-ACTH secretion pheochromocytoma.
After metyrapone administration, not only serum cortisol but also plasma ACTH levels were exponentially decreased almost in parallel, suggesting a glucocorticoid-driven positive-feedback regulation in this rapidly exacerbated ectopic ACTH-producing pheochromocytoma.
The clinical presentation of adrenocorticotropic hormone-secreting pheochromocytoma and adrenal medullary hyperplasia can be anything from mild to dramatic.
We conclude that pheochromocytomas express the POMC gene and that the long POMC-like mRNAs in these tumors and, probably, those in normal adrenal and testis arise from transcription initiating at sites upstream from the normal site used in pituitary.
Immunoreactive (IR) POMC peptides have been detected in several human nonpituitary tissues and most pheochromocytomas and lung cancers, including those not associated with ectopic ACTH syndrome.
The quantities of preproenkephalin A mRNA in nine pheochromocytoma tissues significantly correlated with those of immunoreactive Met-Enk in these tissues (r = 0.94, P less than 0.01).
Different opioid peptides, related to the enkephalins, dynorphins and beta-endorphin have also been detected in tissues outside the CNS including the adrenal medulla and in pheochromocytomas.
The length of POMC mRNA in MTCs (present in all 4 metastases investigated but not in 7 primary tumors) and pheochromocytomas is about 100 nucleotides more than pituitary POMC RNA.
This probe hybridizes specifically to a species of poly(A)-RNA from adrenal medulla and human pheochromocytoma, (1400--1450 bases), and also to [Met]enkephalin-containing pro-opiomelanocortin mRNAs from bovine pituitary (1200 bases) and from mouse pituitary tumor cell (1100 bases).