The Role of EZH2 Inhibitor, GSK-126, in Seizure Susceptibility.

GSK-126 is recognized as an inhibitor of enhancer of zeste homolog-2 (EZH2) activity. Because of its inhibition of EZH2 activation, GSK-126 is considered a potential anti-tumor drug. EZH2 is a histone methyltransferase that catalyzes histone 3 tri-methylation at lysine 27 (H3K27me3), resulting in gene silencing. A previous report showed that decreased H3K27me3 levels in the hippocampus may promote seizure susceptibility, possibly restricting the clinical application of GSK-126. The role of GSK-126 in seizure susceptibility was investigated in this study. We first determined a critical concentration of pentamethazol (PTZ) under which mice exhibit no seizures. We then found that mice pretreated with GSK-126 and injected with the same concentration of PTZ experienced marked convulsions. Peripheral injections of GSK-126 decreased H3K27me3 levels in the hippocampus of mice, while some seizure-related genes (Oasl1, Sox7, armcx5, Ncx3, etc.) were found to be differentially expressed in the hippocampus of those mice . These differences in the expression levels might reflect the crucial role of these genes and related pathways in the promotion of seizure susceptibility. Our results suggest that GSK-126 promotes seizure susceptibility due to its role as an EZH2 inhibitor. These findings may provide evidence to support the development of GSK-126 as a clinical drug.