RNA profiling of human growth hormone-secreting and non-functioning pituitary adenomas reveals novel and differentially expressed immune related genes

Pituitary neuroendocrine tumours (PitNETs) are broadly classified as non-functioning pituitary adenomas (NFPAs) and functional pituitary adenomas (FPAs) which include growth hormone secreting adenomas (GHPAs). Since the role of the immune system in PitNET pathogenesis is still poorly understood, we employed RNA-sequencing technology to unravel differentially expressed genes in GHPAs and NFPAs. Here we present an RNA-sequencing workflow of GHPAs (n=3) and NFPAs (n=7) which revealed a total of 7945 differentially expressed genes. Reactome, Gene Ontology and KEGG pathway analysis further revealed 57 genes involved in immune regulation. These genes fell into functional categories of chemokines, cytokines, interleukins, signal transduction and adhesion molecules. 6 immune genes including GATA3, CCL3, and CXCL9 were selected for further validation by qRT-PCR in 14 additional PitNET samples. A number of possible pathways implicated in PitNET functioning were also highlighted. The most significant were ‘T 1 and T 2 cell differentiation’, ‘cytokine-cytokine receptor pathway’, and ‘chemokine receptors bind chemokines’. Through our findings, we highlight distinct gene expression profiles in NFPAs and GHPAs and suggest that some of these genes could be considered as novel PitNET diagnostic markers for these two subtypes. We are currently validating these novel markers by immunohistochemistry in an array of PitNET subtypes.peer-reviewe