Introduction: Primary bilateral macronodular adrenal hyperplasia (PBMAH) are benign adrenocortical disease responsible for benign tumors and cortisol autonomous secretion. There is a broad spectrum of clinical, imaging and hormonal presentations. Aberrant membrane receptor expression is frequent, the most characteristic example being the food dependent Cushing syndrome due to ectopic expression of the GIP receptor (GIP-R). In 20 to 25 % of these patients, inactivating heterozygous germline mutation of ARCMC5 explains the development of the disease. The aim of this study was to characterize the molecular alterations in PBMAH and to see whether integrated genomics could identify molecular groups explaining this disease heterogeneity.
Methods: Nucleic acids were extracted from macronodules of adrenal frozen tissue collected in the COMETE tumor bank for 36 PBMAH operated patients. 15/36 patients had a germline ARMC5 mutation. RNA and micro RNA have been sequenced using Illumina technology/Genomic platform, Cochin Institute. We used Illumina HumanCore BeadChips (306,702 SNPs) to analyze copy-number alterations in these samples, and Illumina MethylationEPIC BeadChip array (866,895probes) to profile DNA methylation.
Results: Half of the tumor samples did not show any chromosomal alterations. A copy neutral LOH of 16p (ARMC5 locus) was observed in 6 patients who carried an ARMC5 mutation. Gain at 1q was observed in 5 patients and gain at 9q21.11–9q34.3 (SF1 locus) in 3 patients. Using the 5000 more differentially methylated positions (SD based classification), we identified two clusters including one corresponding to the ARMC5 mutated PBMAH. Similarly a specific miRNome profile is observed in the ARCM5 PBMAH. Transcriptome analysis showed two main clusters: one containing the ARMC5 mutated PBMAH and one with the WT PBMAH. Interestingly two sub-groups with different gene expression profiles were observed in the WT cluster, suggesting molecular heterogeneity in WT PBMAH. The GIP-R was over expressed in one of these two sub-group (fold change 5.8, P = 5.7E-09) suggesting a specific molecular profile for food-dependent Cushing PBMAH.
Conclusion: This is the first integrated genomic analysis of PBMAH. It demonstrates molecular heterogeneity of this disease. Three molecular classes of PBMAH determined by gene expression profile, methylome and miRNome are identified: one driven by ARMC5 mutation and one characterized by GIP-R overexpression. The third one needs to be further investigated. This clusterisation will help to better understand PBMAH pathophysiology and to improve its classification.
05 Sep 2020 - 09 Sep 2020