OR04-3 Genetic Alterations of ARMC5 and KDM1A Are Associated With Different Expression Profiles of Illegitimate Receptors in Primary Bilateral Macronodular Adrenal Hyperplasia

INTRODUCTION: Primary Bilateral Macronodular Adrenal Hyperplasia (PBMAH) is a heterogeneous disease characterized by bilateral adrenal macronodules responsible for adrenal Cushing. To date, two genetic causes of PBMAH are known: germline inactivating variants of the tumor suppressor genes ARMC5 identified in 2013 (Assié, N Eng J Med 2013), responsible for 20 to 25% of index cases, and KDM1A, identified recently (Vaczlavik, GIM 2021; Chasseloup, Lancet D&E 2021), responsible for the rare presentation associated with food-dependent Cushing's syndrome (FDCS) due to aberrant expression of the GIP receptor (GIPR) in adrenocortical cells. Multiple other illegitimate receptors are known to be responsible for abnormal cortisol response to various physiological stimuli in PBMAH. A recent multiomic analysis, identified three distinct molecular PBMAH groups: G1 with ARMC5-mutated tumors, G2 with KDM1A-mutated tumors from FDCS patients, and G3 with no identified genetic cause at present. We aimed to identify specific expression profiles of illegitimate receptors in the three groups. METHODS: Based on the transcriptome data obtained by RNA sequencing (Illumina) of the tumors from 31 patients (G1/ARMC5, 16 patients; G2/KDM1A, 6 patients; G3, 9 patients), expression of the following genes, encoding potential illegitimate receptors, were compared: ADRA1A, ADRA1B, ADRA1D, ADRA2A, ADRA2B, ADRA2C, ADRB1, ADRB2, ADRB3, AVPR1A, AVPR1B, AVPR2, GCGR, GIPR, HTR4, HTR7, LHCGR. Calculations were performed using R statistical software. The Bioconductor limma package was used to analyze mRNA differential expression. RESULTS: G1/ARMC5 tumors showed a relative overexpression of the vasopressin receptors AVPR1A and AVPR1B compared to the two other groups (fold-change [FC] =7.39, p<0.001 and 3.98, p<0.001, respectively) but a lower expression of AVPR2 (FC=0.43, p=0.015). G2/KDM1A tumors showed a dramatic overexpression of GIPR compared to the two other groups (FC=105.02, p<0.001) but also of the adrenergic receptors ADRA1D and ADRA2A (FC=2.93, p=0.027 and 9.99, p<0.001, respectively) and of the LH/hCG receptor (LHCGR) (FC=12.20, p<0.001). G3 tumors showed a slight overexpression of the adrenergic receptor ADRA1B (FC=3.49, p=0.001) and in few tumors ADRA1D, AVPR2 and LHCGR were highly expressed suggesting molecular heterogeneity in G3. CONCLUSION: This study reveals specific expression profiles of illegitimate receptors related to the three molecular groups. ARMC5 tumors are associated with the overexpression of two vasopressin receptors, while, besides GIPR, KDM1A inactivation seems to drive the overexpression of the LH/hCG receptor, as previously suggested in patients with FDCS (Bertherat, JCE&M 2005), potentially responsible for Cushing's syndrome associated with pregnancy and menopause. These molecular patterns need to be corroborated by clinical data with a systematic testing of the aberrant cortisol responses. Additionally, further studies would be needed to investigate the clinical relevance and significance of moderate fold-changes in gene expression (e.g. <4). Presentation: Saturday, June 11, 2022 12:00 p.m. - 12:15 p.m.