Aberrant expression of hormone receptors in adrenal Cushing's syndrome

Abstract

In recent years, a novel understanding of the pathophysiology of adrenal Cushing's syndrome has emerged. The ectopic or aberrant expression of G-protein-coupled hormone receptors in the adrenal cortex was found to play a central role in the regulation of cortisol secretion in ACTH-independent macronodular adrenal hyperplasia (AIMAH) and in some unilateral adrenal adenomas. Various aberrant receptors, functionally coupled to steroidogenesis, have been reported: GIP, vasopressin, beta-adrenergic, LH/hCG, and serotonin receptors have been best characterized, but angiotensin, leptin, glucagon, IL-1 and TSH receptors have also been described. The molecular mechanisms responsible for the aberrant expression of these receptors are currently unknown. One or many of these aberrant receptors are present in most cases of AIMAH and in some cases of adrenal adenomas with overt or sub-clinical secretion of cortisol. Clinical protocols to screen for such aberrant receptors have been developed and should be performed in all patients with AIMAH. The identification of such aberrant regulation of steroidogenesis in AIMAH provides the novel opportunity to treat some of these patients with pharmacological agents that either suppress the endogenous ligand or block the aberrant receptor, thus avoiding bilateral adrenalectomy.