Characterization Of Adrenocorticotropic Hormone-Secreting Pituitary Adenomas By Whole-Genome Sequencing

Objective:Pituitary adrenocorticotropic hormone adenoma are one kind of the common functional pituitary adenomas. Pituitary ACTH adenoma causes a variety of symptoms and compressions like truncal obesity, hyperglycemia and hyperlipidemia, due to disturbance of cortisol metabolism resulting from excessive ACTH secretion. The study was carried out to provide more data of molecular mechanism of the pathogenesis of adrenocorticotropic hormone-secreting pituitary adenomas.Patients and design:Whole-genome sequencing was performed to analyze single nucleotide variation, insertions and deletions (indels), copy number variation, structure variation of the genomic sequences of pituitary adenoma tissues derived from Cushing’s disease patients.48 newly diagnosed patients with pituitary ACTH adenomas, who accepted transsphenoidal surgery then, were recruited and consent obtained for excised adenoma tissues.Results:For the sake of reliability of whole-genome analysis, sequencing qualities, depth and coverage were well evaluated. The main results are as follows. USP8 hotspot mutations were identified in 24 of 48 (50.0%) patiets by sequence alignments for single nucleotide variation and indels. And these mutations were grouped into 6 types. Copy number variation of USP8 was found in one patient. Plasma ACTH levels were higher in patients of USP8-mutant group than those of USP8-wild type group. Mutations of cancer driver genes, such as TP53, ATR, KMT2C and NF1, were identified in 2 of 9 patients. Chromosomes loss was found in 1 of 9 patients indicated by copy number variation analysis. Structural variations were detected in patients’adenoma tissues and future research is needed. However, there was no variation found 2 of 9 patients, which means the molecular pathogenesis of pituitary adenomas of the 2 patients was not clear yet.Conclusions:The present study reports the validation of USP8 hotspot mutations in adrenocorticotropic-secreting pituitary hormone adenoma patients which were also identified by earlier studies. And the mutations and CNV lead to excessive secretion of ACTH, resulting in pituitary ACTH adenomas. Furthermore, whole-genome sequencing was first introduced to analysis of pituitary ACTH adenomas. The analysis identified SNVs or indels of tumor suppressor genes and variations of chromosomes in other patiens, offering another potential genetic mechanism of pituitary ACTH adenomas.