OR08-01 Expression of Gonadal Differentiation Markers in Bilateral Macronodular Adrenocortical Disease

Disclosure: K. De Sousa: None. V. Pautasso: None. C. Duparc: None. S. Renouf: None. B. Ragazzon: None. F. Violon: None. L. Bouys: None. F. Bonnet-Serrano: None. M. Sibony: None. N. Driessens: None. S. Espiard: None. G. Raverot: None. J.Y. Bertherat: None. E. Louiset: None. H. Lefebvre: None. Context: Bilateral macronodular adrenocortical disease (BMAD) is a rare cause of primary Cushing syndrome, occurring mostly in women. ARMC5 and KDM1A mutations are responsible for distinct forms of BMAD. In particular, KDM1A mutations are associated with food-dependent Cushing syndrome. In addition, BMAD tissues can express illegitimate receptors, including LH receptor, that lead to aberrant control of cortisol secretion by various factors. Moreover, steroidogenic cells are able to abnormally produce bioactive factors, such as ACTH and the Leydig cell hormone INSL3. Since LH receptor, ACTH and INSL3 are known to be produced in gonads, we speculated on a gonadal-like differentiation of adrenocortical cells in BMAD tissues. Aim: The aim of our study was to investigate the presence of different gonadal markers in a series of BMAD tissues, and to search for secretion of adrenal and gonadal hormones by BMAD cells. Methodology: Gene expression of gonadal markers were evaluated by RNAseq. Immunohistochemical studies were performed on 41 BMAD and 9 normal adrenal samples to examine the presence of hormones (ACTH, INSL3, anti-Mullerian hormone [AMH]), the estrogen synthetizing enzyme aromatase, and transcription factors (GATA4, SOX9, FOXL2, MAGEA4) known to be expressed in testis or ovary. Perifusion experiments, coupled to immunoassays or liquid chromatography/mass spectrometry, were conducted to quantify hormone secretion by 2 adrenal explants. Results: BMAD tissues were collected from patients (60% women) without or with ARMC5 (32%) or KDM1A (13%) mutations. ARMC5-mutated tissues overexpressed FOXL2 and CYP19A1 (encoding aromatase) in comparison with other BMAD samples. In normal adrenals, cortisol-producing cells, located in the zona fasciculata, were immunonegative for INSL3, AMH, aromatase, GATA4 and SOX9, whereas FOXL2 and MAGEA4 immunostainings were detected in the cortex. In BMAH tissues, the presence of positive cells for ACTH (100% of BMAD), INSL3 (90%), AMH (50%), aromatase (77%), SOX9 (92%), GATA4 (97%), FOXL2 (100%) and MAGEA4 (100%) were observed in most of the samples regardless of the gender or mutational status. FOXL2 and MAGEA4 immunostainings were detected throughout BMAD tissues. Distribution of other gonadal markers was heterogenous in tissue sections with clusters of cells positive for ACTH, aromatase and GATA4 or ACTH and SOX9. Functional studies revealed pulsatile secretion of different glucocorticoids and INSL3 by BMAD explants. ACTH and hCG stimulated steroid production but were without effect on INSL3 release. Conclusion: These data show that steroidogenic cells in BMAD tissues exhibit a gonadal-type phenotype and abnormally secrete INSL3. They suggest that BMAD may result from a genetically driven defect occurring during early embryogenesis and affecting differentiation and development of adrenal tissues. Presentation: Friday, June 16, 2023