Downregulation of miR-196b Promotes Glioma Cell Sensitivity to Temozolomide Chemotherapy and Radiotherapy.

Human glioma is the most common type of primary brain tumor. The survival rate of people with a malignant glioma is extremely low, primarily due to a lack of effective treatments. We previously reported that miR-196b expression is upregulated in glioblastoma tissues and overexpression of miR-196b is associated with poor prognosis. miR-196b acts as an oncogene by enhancing cellular proliferation and increasing the expression of E2F1, which plays an important role in the PI3K/AKT signaling pathway. In the present study, we explored the effects of miR-196b expression on glioma cells and characterized the relationship between miR-196b expression and the PI3K/AKT signaling pathway. We found that downregulation of miR-196b decreased the proliferation of U87 and U251 glioma cells. When anti-miR-196b and radiotherapy were used together, cellular proliferation decreased, whereas apoptosis and caspase 3/7activity, an indicator of apoptosis, increased. Meanwhile, downregulation of miR-196b remarkably inhibited glioma cell growth and colony formation when concurrent with temozolomide administration. Further studies demonstrated that neither upregulation nor downregulation of miR-196b markedly changed the protein expression levels of downstream molecules in the PI3K/AKT signaling pathway in cellular experiments. Therefore, whether miR-196b plays a role by activating the PI3K/AKT signaling pathway has not yet been determined. Together, our findings indicate that downregulation of miR-196b increased glioma cell sensitivity to temozolomide chemotherapy and radiotherapy and may be a valuable target when treating malignant gliomas. However, further studies are required to accurately characterize the mechanism by which miR-196b elicits its pivotal role.