Whole‐exome sequencing was performed using NimbleGen MedExome capture (Roche NimbleGen, Madison, WI, USA) from 1 μg of high quality genomic DNA, followed by sequencing of libraries using paired-end mode (2x 75bp) on a Nextseq 500 platform (Illumina, San Diego, CA, USA), at the Genomics Platform of the Cochin Institute. Reads were aligned on hg19 (GRCh37) using BWA V0.7.17.
Small RNA (<100 bases in length) were purified from total RNA using miRNeasy kit (Qiagen), then sequenced. Libraries were prepared at the Genomics Platform of the Cochin Institute, following the TruSeq small RNA protocol (Illumina), starting from 1 µg of high quality total RNA. Single read (1 × 75 bp) sequencing was performed on a Nextseq 500 platform (Illumina). FASTQ sequences were aligned on miRBase v.2052, then counted with STAR (v.2.5.2a).
Total RNA was extracted using RNAble (Eurobio), cleaned-up with RNeasy columns (Qiagen) and sequenced. The libraries were prepared at the Genomics Platform of the Cochin Institute, following the TruSeq Stranded mRNA protocol (Illumina), starting from 1 µg of high quality total RNA. Paired end (2 × 75 bp) sequencing was performed on a Nextseq 500 platform (Illumina). FASTQ sequences were aligned on hg19 (GRCh37) human reference genome with STAR (v.2.5.2a)
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.
