Gene expression profiling in human corticotroph tumours reveals distinct, neuroendocrine profiles

Adrenocorticotrophic hormone (ACTH)‐secreting pituitary adenomas give rise to a severe endocrinological disorder, comprising Cushing's disease, with multifaceted clinical presentation and treatment outcomes. Experimental studies suggest that the disease variability is inherent to the pituitary tumour, thus indicating the need for further studies into tumour biology. The present study evaluated transcriptome expression pattern in a large series of ACTH‐secreting pituitary adenoma specimens in order to identify molecular signatures of these tumours. Gene expression profiling of formalin‐fixed, paraffin‐embedded specimens from 40 human ACTH‐secreting pituitary adenomas revealed the significant expression of genes involved in protein biosynthesis and ribosomal function, in keeping with the neuroendocrine cell profile. Unsupervised cluster analysis identified 3 distinct gene profile clusters and several genes were uniquely overexpressed in a given cluster, accounting for different molecular signatures. Of note, gene expression profiles were associated with clinical features, such as the age and size of the tumour. Altogether, the findings of the present study show that corticotroph tumours are characterised by a neuroendocrine gene expression profile and present subgroup‐specific molecular features.