MicroRNA 145 may play an important role in uveal melanoma cell growth by potentially targeting insulin receptor substrate-1.
BACKGROUND
MicroRNAs (miRNAs) contribute to tumorigenesis by acting as either oncogenes or tumor suppressor genes. In this study, we investigated the role of miR-145 in the pathogenesis of uveal melanoma.


METHODS
Expression profiles of miRNAs in uveal melanoma were performed using Agilent miRNA array. Quantitative real-time polymerase chain reaction was used to screen the expression levels of miR-145 in normal uveal tissue, uveal melanoma tissue, and uveal melanoma cell lines. Lenti-virus expression system was used to construct MUM-2B and OCM-1 cell lines with stable overexpression of miR-145. Cell proliferation, cell cycle, and cell apoptosis of these miR-145 overexpression cell lines were examined by MTT assay and flow cytometry respectively. The target genes of miR-145 were predicted by bioinformatics and confirmed using a luciferase reporter assay. The expression of insulin-like growth factor-1 receptor (IGF-1R), insulin receptor substrate-1 (IRS-1) proteins was determined by Western blotting analysis. IRS-1 was knocked down in OCM-1 cells. TUNEL, BrdU, and flow cytometry assay were performed in IRS-1 knocked down OCM-1 cell lines to analyze its function.


RESULTS
Forty-seven miRNAs were up regulated in uveal melanoma and 61 were down regulated. miR-145 expression was significantly lower in uveal melanoma sample and the cell lines were compared with normal uveal sample. Overexpression of miR-145 suppressed cell proliferation by blocking the G1 phase entering S phase in uveal melanoma cells, and promoted uveal melanoma cell apoptosis. IRS-1 was identified as a potential target of miR-145 by dual luciferase reporter assay. Knocking down of IRS-1 had similar effect as overexpression of miR-145.


CONCLUSIONS
miR-145 might act as a tumor suppressor in uveal melanoma, and downregulation of the target IRS-1 might be a potential mechanism.
Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Key Laboratory of Ophthalmology and Visual Science, Beijing 100730, China.
Yang
Y
Li
Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Key Laboratory of Ophthalmology and Visual Science, Beijing 100730, China.
Qiming
Q
Huang
Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Key Laboratory of Ophthalmology and Visual Science, Beijing 100730, China.
Xuehui
X
Shi
Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Key Laboratory of Ophthalmology and Visual Science, Beijing 100730, China.
Xiang
X
Jin
Department of Cell Biology, Peking University Health Science Center,; Peking University Stem Cell Research Center, Beijing 100191, China.
Li
L
Shen
Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Key Laboratory of Ophthalmology and Visual Science, Beijing 100730, China.
Xiaolin
X
Xu
Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University; Beijing Key Laboratory of Ophthalmology and Visual Science, Beijing 100730, China. Email: weiwenbintr@163.com).
Wenbin
W
Wei
D017209:Apoptosis / Q000235:genetics / Q000502:physiology; D015153:Blotting, Western; D002453:Cell Cycle / Q000235:genetics / Q000502:physiology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000235:genetics / Q000502:physiology; D006801:Humans; D066298:In Vitro Techniques; D055504:Insulin Receptor Substrate Proteins / Q000235:genetics / Q000378:metabolism*; D008545:Melanoma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D014604:Uveal Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D000098943:Uveal Melanoma
D055504:Insulin Receptor Substrate Proteins; D035683:MicroRNAs