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Keywords:

  • MCM7;
  • medulloblastoma;
  • microRNA;
  • miR-106b;
  • PTEN

Aims

MicroRNAs (miRNAs) are an abundant group of small non-coding RNAs that have been implicated in tumorigenesis. They regulate expression of target genes by complementary base pairing. The purposes of this study were to delineate miR-106b expression in medulloblastoma (MB) and to explore its functional contributions to MB pathogenesis.

Methods

We analysed expression of miR-106b in 32 MB samples by quantitative RT-PCR. We applied gain- and loss-of-function strategies to delineate the functional roles of miR-106b in MB. Luciferase reporter assay was conducted to confirm target gene of miR-106b.

Results

Expression of miR-106b was overexpressed in MB, and was significantly associated with its host gene MCM7 (P = 0.020). Transfection of miR-106b inhibitor in MB cell lines markedly reduced cell proliferation, migration and invasion potential, and tumour sphere formation. Cell cycle analysis indicated that miR-106b inhibition induced G1 arrest and apoptosis. The cell cycle regulators, p21 and cyclin D1, and apoptotic marker cleaved PARP were differentially expressed in miR-106b inhibitor-transfected cells. PTEN was identified as a direct target gene of miR-106b. Luciferase reporter assay confirmed miR-106b directly interacted with the 3′ UTR of PTEN. We found miR-106b directly targeted PTEN at transcriptional and translational levels. Immunohistochemistry revealed a trend between PTEN and miR-106b in MB tumours (P = 0.07).

Conclusions

These data suggested the upregulation of miR-106b in MB and the involvement of miR-106b in MB biology.