Regulation of aryl hydrocarbon receptor interacting protein (AIP) protein expression by MiR-34a in sporadic somatotropinomas.

Abstract

INTRODUCTION:

Patients with germline AIP mutations or low AIP protein expression have large, invasive somatotroph adenomas and poor response to somatostatin analogues (SSA).

METHODS:

To study the mechanism of low AIP protein expression 31 sporadic somatotropinomas with low (n = 13) or high (n = 18) AIP protein expression were analyzed for expression of AIP messenger RNA (mRNA) and 11 microRNAs (miRNAs) predicted to bind the 3'UTR of AIP. Luciferase reporter assays of wild-type and deletion constructs of AIP-3'UTR were used to study the effect of the selected miRNAs in GH3 cells. Endogenous AIP protein and mRNA levels were measured after miRNA over- and underexpression in HEK293 and GH3 cells.

RESULTS:

No significant difference was observed in AIP mRNA expression between tumors with low or high AIP protein expression suggesting post-transcriptional regulation. miR-34a was highly expressed in low AIP protein samples compared high AIP protein adenomas and miR-34a levels were inversely correlated with response to SSA therapy. miR-34a inhibited the luciferase-AIP-3'UTR construct, suggesting that miR-34a binds to AIP-3'UTR. Deletion mutants of the 3 different predicted binding sites in AIP-3'UTR identified the c.*6-30 site to be involved in miR-34a's activity. miR-34a overexpression in HEK293 and GH3 cells resulted in inhibition of endogenous AIP protein expression.

CONCLUSION:

Low AIP protein expression is associated with high miR-34a expression. miR-34a can down-regulate AIP-protein but not RNA expression in vitro. miR-34a is a negative regulator of AIP-protein expression and could be responsible for the low AIP expression observed in somatotropinomas with an invasive phenotype and resistance to SSA.

• Authors: Judit Dénes, Leandro Kasuki, Giampaolo Trivellin, Leandro M Colli, Christina M Takiya, Craig E Stiles, Sayka Barry, Margaret de Castro, Mônica R Gadelha, Márta Korbonits
• Journal: PloS one (PLoS One) Vol. 10 Issue 2 Pg. e0117107 ( 2015) ISSN: 1932-6203 [Electronic] United States
• PMID: 25658813 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Intracellular Signaling Peptides and Proteins
• MIRN34 microRNA, human
• MicroRNAs
• RNA, Messenger
• aryl hydrocarbon receptor-interacting protein
• Keratins

Topics

• Adult
• Animals
• Base Sequence
• Binding Sites
• Cell Line, Tumor
• Female
• Gene Expression Regulation, Neoplastic
• Growth Hormone-Secreting Pituitary Adenoma (genetics, pathology)
• HEK293 Cells
• Humans
• Intracellular Signaling Peptides and Proteins (chemistry, genetics, metabolism)
• Keratins (metabolism)
• Male
• MicroRNAs (chemistry, metabolism)
• Middle Aged
• Neoplasm Invasiveness
• Pituitary Neoplasms (genetics, pathology)
• RNA, Messenger (metabolism)
• Rats
• Sequence Alignment