Characterisation of a GNAS variant linked to cortisol-producing adrenocortical adenoma

• Published in: Endocrine oncology Vol. 5; no. 1; p. e250009
• Main Authors: Jamaluddin, Aqfan, Wyatt, Rachael, Pasaliu, Andreea, Ruggles, Oliver, Calebiro, Davide, Gorvin, Caroline M, Ronchi, Cristina L
• Format: Journal Article
• Language: English
• Published: England Bioscientifica Ltd 01.01.2025
• Subjects: cAMP/PKA signalling; ACTH receptor; somatic mutation; cortisol-producing adenomas; G protein
• ISSN: 2634-4793; 2634-4793
• DOI: 10.1530/EO-25-0009

Adrenocortical adenomas are frequent in the general population and can be associated with autonomous cortisol excess, increasing morbidity and mortality. Altered cAMP/PKA signalling is common in sporadic cortisol-producing adenomas, typically due to somatic activating mutations in the catalytic subunit α of PKA ( ) or the G-protein α subunit, Gα ( ), which activate cAMP signalling. We previously identified a novel p.Lys58Gln somatic variant in a patient with a 5.3 cm adenoma and overt Cushing's syndrome. This novel mutation was not charactersised before but provided enough evidence to warrant further investigation. Using HEK293 cells depleted of , we established wild-type (WT) Gα and Gα -Lys58Gln stable cell lines and evaluated adrenocorticotropic hormone (ACTH) receptor signalling using a cAMP GloSensor assay, measured CREB transcription factor phosphorylation (pCREB) by AlphaLISA and assessed luciferase reporter activity. Cell viability and apoptosis were also assessed over 5 days. The Gα -Lys58Gln variant showed a significantly higher basal cAMP, pCREB and luciferase reporter concentration and a greater response to ACTH (0-10 nM, < 0.001) compared to WT Gα . The variant had no effect on ligand potency. There was also significantly enhanced cell viability and apoptosis in cells with the Gα -Lys58Gln variant. In conclusion, our study demonstrated that the Gα -Lys58Gln variant is associated with constitutive activation of GNAS signalling, similar to Arg201 mutations previously reported in adrenocortical adenomas, potentially representing a new pathogenic mechanism in a subset of patients with adrenal Cushing syndrome. This variant may also affect cell proliferation and requires further study.