Rasagiline suppresses glioblastoma cell survival through oxidative stress-mediated modulation of TLR4/NF-Κb signaling and apoptosis

Glioblastoma (GBM) is the most aggressive primary brain tumor in adults and remains associated with poor prognosis despite multimodal treatment. The identification of clinically approved drugs with novel antitumor activities has emerged as a promising strategy for accelerating therapeutic development. Rasagiline, an irreversible monoamine oxidase-B inhibitor widely used for the treatment of Parkinson’s disease, has demonstrated neuroprotective properties; however, its effects on glioblastoma biology remain largely unknown.

The present study investigated the concentration-dependent effects of rasagiline on oxidative stress, inflammatory signaling, and apoptotic responses in two human glioblastoma cell lines, U87-MG and T98G. Cells were treated with 2.5, 5, 10, 20, and 40 µM rasagiline for 24 h. Cell viability was evaluated using the MTT assay, while membrane integrity was assessed by lactate dehydrogenase (LDH) protein concentration.

Oxidative stress biomarkers (superoxide dismutase, reduced glutathione, and malondialdehyde), inflammatory mediators (IL-1β, IL-6, and TNF-α), TLR4, NF-κB, and caspase-3 levels were determined by ELISA. Immunofluorescence staining was performed to assess TLR4 and NF-κB expression. Rasagiline produced concentration-dependent effects on glioblastoma cell viability and cellular injury, with more pronounced responses observed at intermediate-to-high concentrations.

Treatment with rasagiline disrupted intracellular redox homeostasis, as evidenced by increased SOD protein concentration and MDA levels together with depletion of GSH. At intermediate concentrations, particularly around 10 µM, rasagiline produced coordinated alterations in oxidative stress-related and inflammatory parameters, accompanied by modulation of TLR4/NF-κB-related responses. IL-1β and TNF-α levels increased at selected intermediate concentrations, whereas IL-6 levels progressively decreased with increasing rasagiline concentrations.

Caspase-3 protein levels increased particularly at higher concentrations, suggesting an association between rasagiline-induced cellular stress and apoptotic signaling. Immunofluorescence findings further supported the concentration-dependent modulation of TLR4 and NF-κB. Although the magnitude of the responses differed between U87-MG and T98G cells, both models demonstrated broadly similar concentration-dependent response patterns, with 10 µM representing a biologically active intermediate concentration for mechanistic interpretation.

In conclusion, rasagiline produced concentration-dependent cytotoxic effects in glioblastoma cells, accompanied by alterations in redox homeostasis, inflammatory signaling, and caspase-3-associated apoptotic responses. These findings provide a basis for further investigation of rasagiline as a potential drug-repurposing candidate in glioblastoma, particularly through mechanistic and in vivo studies. This work was supported by Coordination Unit of Scientific Research Projects of Hitit University (Project number: FEF19004.25.003).