Pangenomic classification of pituitary adenomas

Pituitary neuroendocrine tumors (PitNETs) are common. They are classified in five main histological types: PitNETs of POU1F1 (Pit1) lineage -lactotroph, somatotroph and thyrotroph -, gonadotroph, and corticotroph PitNETs. Pituitary tumorigenesis is poorly understood. We report here a pangenomic characterization of 134 PitNETs from all types, based on exome, genome, transcriptome, miRnome and methylome. Pit1 lineage was associated with a specific epigenetic signature of diffuse DNA hypomethylation, and correlated with expression of Pit1 markers and chromosomal instability. 45% of somatotroph PitNETs showed GNAS mutations. GNAS-wild type somatotroph showed a distinct transcriptome profile, expressing gonadotroph transcription factor NR5A1 (SF1). Sparsely granulated somatotroph PitNETs was classified apart from somatotroph, owing to a thyrotroph transcriptome signature. 43% of corticotroph PitNETs showed USP8 mutations, sharing a low epithelial-mesenchimal transition (EMT) transcriptome signature. Silent corticotroph PitNETs showed a gonadotroph transcriptome signature evoking transdifferentiation, and lost somatostatin target SSTR5 expression.EGA study EGAS00001003642