Characterization of microRNA‐10b in human Glioblastoma

Glioblastoma is a common, very deadly and highly invasive malignant brain tumor. MicroRNAs are small noncoding regulatory RNA molecules that modulate protein expression by binding to the 3′‐untranslated region of mRNA, promoting RNA degradation and inhibiting transcription. In this study, we show that microRNA‐10b (miR‐10b) is deregulated in glioblastoma where it regulates tumor cell migration and invasion. We assessed the expression of miR‐10b in human glioblastoma cells and stem cells using quantitative RT‐PCR. We found that miR‐10b expression is up‐regulated in all human glioblastoma cell lines and stem cells. We then tested the effects of miR‐10b inhibition on cell cycle status, cell proliferation, invasion, migration, clonogenicity and apoptosis. Inhibition of miR‐10b only mildly decreased the proliferation of established glioblastoma cell lines but exhibited greater inhibition on the proliferation of stem cells. Importantly, inhibition of miR‐10b strongly inhibited cell invasion, migration and anchorage‐independent growth in glioblastoma cells and stem cells. Based on microRNA target prediction programs, miR‐10b is expected to bind to the 3′‐UTR of various genes including the tumor suppressor PTEN. We used western blotting to determine that miR‐10b has no effect on the regulation of PTEN. We are currently researching potential targets of miR‐10b that mediate its effects on glioblastoma cell migration and invasion. Our findings suggest that miR‐10b is a tumor promoter that is upregulated in glioblastoma where it induces tumor cell migration and invasion. Consequently, miR‐10b inhibition could be a promising new strategy for glioblastoma therapy.