Abstract 126: Characterization of microRNA-10b in human glioblastoma

Abstract

Abstract Glioblastoma is the most common and deadly malignant brain tumor. One main reason of resistance of glioblastoma to therapy is the ability of the tumor cells to migrate and invade the surrounding brain, rendering total surgical removal of the tumor practically impossible. MicroRNAs are recently discovered small noncoding regulatory RNA molecules with emerging critical roles in cancer. MicroRNAs modulate protein expression by binding to the 3′-untranslated region of mRNA and promoting RNA degradation or inhibiting transcription. By acting on oncogenes and tumor suppressors, microRNAs can behave as tumor suppressors or oncogenes, respectively. In this study, we show that microRNA-10b (miR-10b) is deregulated in glioblastoma where it regulates tumor cell migration and invasion. While analyzing The Cancer Genome Atlas (TCGA) data, we noticed that miR-10b is associated with poor prognosis of glioblastoma patients. We therefore embarked on a comprehensive characterization of miR-10b in glioblastoma. We first assessed the expression of miR-10b in human glioblastoma cells and cancer stem cells using quantitative RT-PCR. We found that miR-10b expression is up-regulated in all human glioblastoma cell lines and glioblastoma stem cells tested as compared to normal human astrocytes. We then tested the effects of miR-10b inhibition on cell cycle status, cell proliferation, cell invasion, cell migration, clonogenicity and apoptosis by propidium iodide flow cytometry, cell counting, transwell invasion assay, scratch assay, soft agar assay and annexin V flow cytometry, respectively. Glioblastoma cells, stem cells or normal human astrocytes were transfected with a specific anti-miR-10b antagomir and assessed for the above functional endpoints. Inhibition of miR-10b had variable effects on cell proliferation. It only mildly decreased the proliferation of established glioblastoma cell lines but exhibited greater inhibition on the proliferation of glioblastoma stem cells. Inhibition of miR-10b did not affect apoptosis or death of any of the tested cells. Importantly, inhibition of miR-10b strongly inhibited cell invasion, cell migration and anchorage-independent growth in glioblastoma cells and stem cells. Conversely, overexpression of miR-10b by transfection of pre-miR-10b in glioblastoma cells promoted tumor cell invasion and migration in vitro. We are currently in the process of researching potential targets of miR-10b that mediate its effects on glioblastoma cell migration and invasion. We are also studying the potential correlation between the levels of miR-10b in human glioblastoma tissues and tumor grade. Altogether, our findings suggest that miR-10b is a tumor promoter that is upregulated in glioblastoma where it induces tumor cell migration and invasion. These preliminary results suggest that targeting miR-10b could be a promising new strategy for glioblastoma therapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 126. doi:10.1158/1538-7445.AM2011-126