Genome wide analysis of circulating miRNAs in growth hormone secreting pituitary neuroendocrine tumor patients' plasma

Objective Circulating plasma miRNAs have been increasingly studied in the field of pituitary neuroendocrine tumor (PitNET) research. Our aim was to discover circulating plasma miRNAs species associated with growth hormone (GH) secreting PitNETs and assess how the plasma levels of discovered miRNA candidates are impacted by SSA therapy and whether there is a difference in their levels between GH secreting PitNETs and other PitNET types. Methods miRNA candidates were discovered using the whole miRNA sequencing approach and differential expression analysis. Selected miRNAs were then analyzed using real-time polymerase chain reaction (qPCR). Results Whole miRNA sequencing discovered a total of 19 differentially expressed miRNAs (DEMs) in GH secreting PitNET patients' plasma 24 hours after surgery and 19 DEMs between GH secreting PitNET patients' plasma and non-functioning (NF) PitNET patients' plasma. Seven miRNAs were selected for further testing of which miR-625-5p, miR-503-5p miR-181a-2-3p and miR-130b-3p showed a significant downregulation in plasma after 1 month of SSA treatment. miR-181a-5p and mir-625-5p were also found to be significantly downregulated in plasma of GH secreting PitNET patients vs. NF PitNET patients. Conclusions Our study suggests that expression of plasma miRNAs miR-625-5p, miR-503-5p miR-181a-2-3p and miR-130b-3p in GH secreting PitNETs is affected by SSA treatment. Additionally, miR-625-5p and miR-181a-5p can distinguish GH secreting PitNETs from other PitNET types warranting further research on these miRNAs for treatment efficacy. Overall design: We compared plasma miRNA content and levels before (*-x) and after surgery (*-24h) focusing on GH secreting PitNET patients. Selected miRNA candidates from our data and literature were then tested in a longitudinal manner in somatostatin analogues (SSA) treatment group. Additionally, we validated selected targets in an independent GH secreting PitNET group. Please note that the samples PitNET44-24h and PitNET44-x were determined to be outliers and excluded from the further analysis.