miR-489 is a tumour-suppressive miRNA target PTPN11 in hypopharyngeal squamous cell carcinoma (HSCC).
BACKGROUND
Hypopharyngeal squamous cell carcinoma (HSCC) is an aggressive malignancy with one of the worst prognoses among all head and neck cancers. Greater understanding of the pertinent molecular oncogenic pathways could help improve diagnosis, therapy, and prevention of this disease. The aim of this study was to identify tumour-suppressive microRNAs (miRNAs), based on miRNA expression signatures from clinical HSCC specimens, and to predict their biological target genes.


METHODS
Expression levels of 365 human mature miRNAs from 10 HSCC clinical samples were screened using stem-loop real-time quantitative PCR. Downregulated miRNAs were used in cell proliferation assays to identify a tumour-suppressive miRNA. Genome-wide gene expression analyses were then performed to identify the target genes of the tumour-suppressive miRNA.


RESULTS
Expression analysis identified 11 upregulated and 31 downregulated miRNAs. Gain-of-function analysis of the downregulated miRNAs revealed that miR-489 inhibited cell growth in all head and neck cancer cell lines examined. The gene PTPN11 coding for a cytoplasmic protein tyrosine phosphatase containing two Src Homology 2 domains was identified as a miR-489-targeted gene. Knockdown of PTPN11 resulted in the inhibition of cell proliferation in head and neck SCC cells.


CONCLUSIONS
Identification of the tumour-suppressive miRNA miR-489 and its target, PTPN11, might provide new insights into the underlying molecular mechanisms of HSCC.
Kikkawa
N
N
Department of Functional Genomics, Graduate School of Medicine, Chiba University, Chiba, Japan.
Hanazawa
T
T
Fujimura
L
L
Nohata
N
N
Suzuki
H
H
Chazono
H
H
Sakurai
D
D
Horiguchi
S
S
Okamoto
Y
Y
Seki
N
N
D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000235:genetics*; D045744:Cell Line, Tumor; D015536:Down-Regulation; D005260:Female; D006801:Humans; D007012:Hypopharyngeal Neoplasms / Q000235:genetics*; D008297:Male; D035683:MicroRNAs / Q000235:genetics*; D008875:Middle Aged; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11 / Q000235:genetics*; D034741:RNA, Small Interfering; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection
C552418:MIRN489 microRNA, human; D035683:MicroRNAs; D034741:RNA, Small Interfering; C516724:PTPN11 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11