Glioblastoma (GBM) is a malignant brain tumor. The purpose of this study is to estimate the potential effects and underlying mechanisms of a ubiquitin-specific protease 8 (USP8) small-molecule inhibitor on the phenotypic characteristics of GBM cells. The growth, migration, invasion, and stemness of GBM LN229 and T98G cells were evaluated by conducting cell proliferation, colony formation, wound healing, transwell, Ki-67 staining, spheroid formation, and ionizing radiation assays, and the results collectively showed the suppressive effects of USP8 inhibition on GBM cells. Furthermore, transcriptomic profiling of GBM cells treated with the USP8 inhibitor deubiquitinase (DUB)-IN-1 revealed significantly altered mRNA expression induced by pharmacological USP8 inhibition, from which we confirmed downregulated Aurora kinase A (AURKA) protein levels using immunoblotting assays. Our findings indicated that the proliferation, invasion, and stemness of LN229 and T98G cells were markedly suppressed by USP8 inhibition. Pharmacological USP8 suppression elicits multiple tumor-inhibitory effects, likely through dysregulating various mRNA expression events, including that of the key cell cycle regulator and oncogenic protein AURKA. Therefore, our observations corroborate the GBM-supportive roles of USP8 and suggest pharmacological USP8 inhibition is a viable therapeutic approach to target GBM. The purpose of this study was to investigate the effect and mechanism of action of the USP8 inhibitor DUB-IN-1 on GBM.

Tanshinone IIA (TanIIA) has neuroprotective effects against cerebral ischemia reperfusion injury (CIRI), but its clinical application is limited due to poor water solubility and robust first pass elimination property. In this study, we developed microemulsion loaded with TanIIA (TanIIA ME) to break through these limitations, and explored the neuroprotective effect of TanIIA ME against CIRI and the epigenetic regulation mechanism of this neuroprotection. In vivo, middle cerebral artery occlusion (MCAO) models were treated with TanIIA ME and TanIIA solution or sodium valproate as a control. The effect of TanIIA ME on HDAC activity was determined by ELISA assay. In addition, we used primary hippocampal neurons to establish oxygen-glucose deprivation and reoxygenation (OGD/R) models. Lactate dehydrogenase (LDH) assay and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay were performed to investigate the neuroprotective efficacy of TanIIA ME. Subsequently, the expression of H3K18ac, H4K8ac, NMDAR1, caspase-3, and MAP-2 were investigated in MCAO or OGD/R models treated with TanIIA ME, TanIIA solution or sodium valproate. In vivo experimental results indicated that TanIIA ME significantly reduced neurological scores, infarction volume, and HDAC activity compared with TanIIA solution and MCAO group, accompanied by upregulation of H3K18ac, H4K8ac, and MAP-2 expression and downregulation of NMDAR1 and caspase-3 expression. Additionally, in OGD/R models, the results demonstrated that TanIIA ME treatment had a better neuroprotective effect along with increased H3K18ac, H4K8ac, and MAP-2 expression and decreased NMDAR1 and caspase-3 expression, compared with the other treatments except sodium valproate. Overall, TanIIA ME treatment exhibited superior efficacy in protecting against CIRI through mechanisms that might involve the inhibition of NMDAR1 and caspase-3 expression and the enhancement of MAP-2 expression by regulating histone H3K18 and H4K8 acetylation. Thus, TanIIA ME could be potentially used to develop a promising drug for the treatment of ischemic stroke.