Activating Mutations of GNAS in Canine Cortisol‐Secreting Adrenocortical Tumors

• Published in: Journal of veterinary internal medicine Vol. 27; no. 6; pp. 1486 - 1492
• Main Authors: Kool, M.M.J., Galac, S., Spandauw, C.G., Kooistra, H.S., Mol, J.A.
• Format: Journal Article
• Language: English
• Published: United States J.B. Lippincott 01.11.2013; Blackwell Publishing Ltd; John Wiley & Sons, Inc
• Subjects: Adenoma - genetics; Adenoma - metabolism; Adenoma - veterinary; Adrenal; Adrenal Cortex Neoplasms - genetics; Adrenal Cortex Neoplasms - metabolism; Adrenal Cortex Neoplasms - veterinary; Animals; Base Sequence; Cancer; Collaboration; Cushing syndrome; Cushing Syndrome - genetics; Cushing Syndrome - metabolism; Cushing Syndrome - veterinary; Cushing's syndrome; Cyclic AMP-Dependent Protein Kinase RIalpha Subunit - genetics; Cyclic AMP-Dependent Protein Kinase RIalpha Subunit - metabolism; DNA Mutational Analysis - veterinary; Dog; Dog Diseases - genetics; Dog Diseases - metabolism; Dogs; Female; Genes; Genomics; Gs alpha; GTP-Binding Protein alpha Subunits - genetics; GTP-Binding Protein alpha Subunits - metabolism; Histocytochemistry - veterinary; Hormones; Hydrocortisone - secretion; Kinases; Male; Molecular Sequence Data; Mutation; Mutation, Missense - genetics; Pathogenesis; Proteins; Receptors, Melanocortin - genetics; Receptors, Melanocortin - metabolism; Reverse Transcriptase Polymerase Chain Reaction - veterinary; RNA - chemistry; RNA - genetics; Sequence Analysis, DNA; Signal transduction; Thyroid gland; Tumors; United States > US; Cushing's syndrome; Adrenal; Dog; Gs alpha
• ISSN: 0891-6640; 1939-1676
• DOI: 10.1111/jvim.12194

BACKGROUND: Cushing's syndrome or hypercortisolism is a common endocrinopathy in dogs. In approximately 15% of cases, the disorder is caused by adrenocorticotropin (ACTH)‐independent hypersecretion of cortisol by an adrenocortical tumor (AT). Without other explanation, the cortisol hypersecretion has been referred to as autonomous. OBJECTIVES: To investigate whether ACTH‐independent hypersecretion of cortisol may be associated with aberrant activation of the melanocortin 2 receptor (MC2R)‐cyclic AMP (cAMP)‐protein kinase A (PKA) pathway. ANIMALS: All analyses were performed on 44 cortisol‐secreting ATs (14 adenomas and 30 carcinomas) derived from dogs diagnosed with ACTH‐independent hypercortisolism. METHODS: Mutation analysis was performed of genes encoding the stimulatory G protein alpha subunit (GNAS), MC2R, and PKA regulatory subunit 1A (PRKAR1A) in all ATs. RESULTS: Approximately one‐third of all ATs harbored an activating mutation of GNAS. Missense mutations, known to result in constitutive activation, were present in codon 201 in 11 ATs, in codon 203 (1 AT), and in codon 227 (3 ATs). No functional mutations were found in MC2R and PRKAR1A. CONCLUSIONS AND CLINICAL IMPORTANCE: Activation of cAMP signaling is a frequent event in canine cortisol‐secreting ATs and may play a crucial role in both ACTH‐independent cortisol production and tumor formation. To the best of our knowledge, this is the first report of potentially causative mutations in canine cortisol‐secreting ATs.