Identification of anti-cancer activities of ixazomib citrate and betulinic acid on glioblastoma cells

Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults. Due to the rapid development of resistance to standard treatment approaches in GBM tumors, it is crucial to identify new therapeutic targets. This study examined the therapeutic potential of the ubiquitin-proteasome mechanism (UPM) in GBM cells. Then, ixazomib citrate (IXaC) and betulinic acid (BA) were selected as potential inhibitory agents that could target this mechanism. The anti-cancer effects of these agents, administered alone or in combination, were assessed in U87MG and T98G GBM cells. Anti-proliferative activity was evaluated using the Cell Viability Detection Kit (CVDK-8). The effects of the agents on the mRNA expression levels of target genes were determined using Real-Time quantitative PCR (RT-qPCR). The impact of IXaC and/or BA on apoptosis and cell cycle profiles of GBM cells was analyzed by flow cytometry. Following IXaC and/or BA treatment, changes in the malignant behavior of GBM cells were determined using clonogenic, wound healing, and soft agar tests. IXaC and/or BA showed anti-proliferative activity in GBM cells. When both agents were combined, an additive effect was found in GBM cells. Treatment with IXaC and/or BA induced apoptosis in GBM cells. The indicated agents were found to induce cell cycle arrest at different phases in GBM cells. IXaC and/or BA significantly reduced the invasion and colony-forming capacities of GBM cells. The findings indicate that targeting the UPM in GBM has anti-cancer potential and could serve as an alternative treatment approach in the context of limited available therapies.