miR-133b acts as a tumor suppressor and negatively regulates EMP2 in glioma

Qiang Zhang, Xiangyun Fan, Baoquan Xu, Qi Pang,  Liangzhu Teng

Abstract:

In recent years, the incidence of neuroglioma (glioma) has trended towards a younger age-group. Gene therapy has been widely implemented and a growing number of microRNAs associated with glioma have been identified. Herein, we detected the expression of micro RNA- miR-133b- in glioma by qPCR and also its effect on cell viability, survival and apoptosis of in vitro U87 and A172 cells. The binding effect of miR-133b on epithelial membrane protein-2 (EMP2) was verified and we then investigated the effect of EMP2 on in vitro glioma cells and tested the expression of apoptosis related factors after administration of altered miR-133b and EMP2 expressions. We found that miR-133b was down-regulated in glioma compared to adjacent non-tumorous tissue and also that its over-expression inhibits cell viability and survival and enhances apoptosis in the U87 and A-172 cells. Moreover, miR-133b effectively binds to EMP2, down-regulates its expression and negates its normal function. EMP2 normally promotes cell apoptosis and reduces cell viability and survival while miR-133b over-expression regulates the expression of apoptotic-associated protein and activates the apoptotic pathway, thus counteracting EMP2 regulation of opposite expression effects. Further, miR-133b can be considered a tumor suppressor because of its low expression and effects on cell apoptosis via down-regulating EMP2 expression and activating the apoptotic cell pathway in glioma. EMP2 is a risk factor for glioma, and miR-133b should prove a potential target for glioma clinical prevention and treatment.