Down-regulation of Wee1 kinase by a specific subset of microRNA in human sporadic pituitary adenomas.
BACKGROUND
The tumorigenic mechanisms involved in pituitary adenomas, especially of nonfunctional pituitary adenomas (NFAs), remains unclear. Various cell cycle inhibitors have been found to be underexpressed in pituitary tumors; however, Wee1 kinase, a nuclear protein that delays mitosis and was recently recognized as a tumor suppressor gene, has not been previously investigated in pituitary tumors.


OBJECTIVE
Our objective was to examine the expression of Wee1 in pituitary tumors and to identify microRNAs (miRs) that can regulate its expression.


METHODS
Expression of Wee1 was examined by immunohistochemistry and quantitative real-time PCR (qRT-PCR). Identification of miRs targeting the Wee1 3'-untranslated region was performed by miR array followed by expression analysis of identified miRs using qRT-PCR. Dual-luciferase assay and transient transfection of miRs into Hela cells followed by immunoblot analysis of Wee1 protein and cell proliferation analysis were carried out.


METHODS
A total of 57 pituitary tissue samples including 27 NFAs, 15 GH-producing adenomas with or without prolactin overproduction, and 15 normal pituitary glands were analyzed.


RESULTS
Wee1 protein expression was decreased in NFAs and GH-producing tumors with or without prolactin production, but no change in mRNA expression was observed with qRT-PCR. A specific subset of five miRNAs revealed by in silico target prediction was significantly overexpressed in NFA samples; three miRs (miR-128a, miR-155, and miR-516a-3p) targeted the 3'-untranslated region of the Wee1 transcript, and exogenous overexpression of these miRs inhibited Wee1 protein expression and HeLa cell proliferation.


CONCLUSIONS
To our knowledge, this is the first report suggesting that regulation of Wee1 kinase by miRs may be linked to pituitary tumorigenesis.
Butz
Henriett
H
Second Department of Medicine, Faculty of Medicine, Semmelweis University, Budapest, Hungary.
Likó
István
I
Czirják
Sándor
S
Igaz
Péter
P
Khan
Mohammed Munayem
MM
Zivkovic
Vladimir
V
Bálint
Katalin
K
Korbonits
Márta
M
Rácz
Károly
K
Patócs
Attila
A
D000236:Adenoma / Q000235:genetics*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D015536:Down-Regulation / Q000187:drug effects; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006367:HeLa Cells; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000235:genetics / Q000494:pharmacology*; D008875:Middle Aged; D009687:Nuclear Proteins / Q000235:genetics*; D020411:Oligonucleotide Array Sequence Analysis; D010911:Pituitary Neoplasms / Q000235:genetics*; D011505:Protein-Tyrosine Kinases / Q000235:genetics*; D013379:Substrate Specificity / Q000187:drug effects
D014408:Biomarkers, Tumor; D018797:Cell Cycle Proteins; D035683:MicroRNAs; D009687:Nuclear Proteins; D011505:Protein-Tyrosine Kinases; C499349:WEE1 protein, human