Valproic acid regulates the miR-155/Jarid2 axis by affecting miR-155 promoter methylation in glioma.

The most frequent primary brain tumor in adults is glioma, yet no effective curative treatments are currently available. Our previous study demonstrated the enhancing effects of JARID2 on glioma sensitivity to TMZ treatment. In this study, miR-155 is predicted to target JARID2. miR-155 is overexpressed in clinical glioma specimens and cell lines. miR-155 overexpression in glioma cells enhances cell viability and represses cell apoptosis. Through targeting, miR-155 inhibits JARID2 expression. miR-155 inhibition inhibits glioma cell viability and enhances cell apoptosis, whereas JARID2 knockdown enhances cell viability and inhibits cell apoptosis; JARID2 knockdown partially reverses miR-155 inhibition effects on glioma phenotypes. miR-155 inhibition reduces but knockdown of JARID2 promotes the tumor formation ability of glioma cells in vivo. Valproic acid (VPA) upregulates JARID2 expression, inhibits glioma cell viability and enhances cell apoptosis. VPA downregulates the expression level of miR-155 by increasing the methylation level of the miR-155 promoter, suggesting that the miR-155/JARID2 axis is implicated in VPA inhibition of glioma cell viability and enhancement of glioma cell apoptosis. This study demonstrates a new mechanism of VPA treatment of gliomas by affecting the miR-155/JARID2 axis, which could be regarded as a new strategy for the prevention and treatment of glioma.