Genetic variations associated with hyperplasias, adenomas of adrenal cortex
Genetic variations of the catalytic subunit of cyclic protein kinase A, or PKA, were linked to the development of bilateral adrenal hyperplasias and unilateral cortisol-producing adrenal adenomas. These effects may activate corticotropin-independent Cushing’s syndrome, according to data published in The New England Journal of Medicine.
“The current study suggests that more than one-third of cortisol-producing adenomas associated with overt Cushing’s syndrome have unique somatic mutations in PRKACA (which encodes the main catalytic subunit of PKA), resulting in constitutive PKA activation,” Felix Beuschlein, MD, of the University of Munich, and colleagues wrote.
The researchers performed an exome sequencing of tumor-tissue specimens from 10 patients with cortisol-producing adrenal adenomas and evaluated their recurrent mutations in candidate genes in 171 additional patients with adrenocortical tumors, according to data.
Somatic mutations in PRKACA were discovered in eight of 10 adenomas. These somatic mutations also were identified in 22 of 59 unilateral adenomas (37%) from patients with overt Cushing’s syndrome; mutations were not detectable in 40 patients with subclinical hypercortisolism or in 82 patients with other adrenal tumors, according to data.
Five of the 35 patients with cortisol-producing hyperplasias appeared to be carriers of the germline duplication of the genomic region on chromosome 19 that includes PRKACA, researchers wrote.
In vitro study data indicated that PKA catalytic subunit genetic mutations impaired inhibition by the PKA regulatory subunit, and cells from patients with germline chromosomal gains appeared to increase the protein levels of the subunit.
“Because PRKACA mediates most of the effects of inactivating PRKAR1A mutations and because mutations of PRKAR1 are associated with a variety of tumors in humans and mice, we would speculate that somatic PRKACA defects might also play a role in other forms of endocrine and nonendocrine tumors,” researchers wrote.
Disclosure: Beuschlein reports financial ties with the European Community, HRA Pharma, Novartis, Viropharma, and Wilhelm-Sander Stiftung.