Synergistic combination of perphenazine and temozolomide suppresses patient-derived glioblastoma tumorspheres

Abstract

Background. Glioblastoma (GBM), a primary malignant brain tumor, has a poor prognosis, even with standard treatments such as radiotherapy and chemotherapy. In this study, we explored the anticancer effects of the synergistic combination of perphenazine (PER), a dopamine receptor D2/3 (DRD2/3) antagonist, and temozolomide (TMZ), a standard treatment for GBM, in patient-derived human GBM tumorspheres (TSs). Methods. The biological effects of the combination of PER and TMZ in GBMTSs were assessed by measuring cell viability, ATP, stemness, invasiveness, and apoptosis. Changes in protein and mRNA expression were analyzed using western blotting and RNA sequencing. Co-administration of PER and TMZ was evaluated in vivo using a mouse orthotopic xenograft model. Results. The Severance dataset showed that DRD2 and DRD3 expressions were higher in tumor tissues than in the tumor-free cortex of patients with GBM. DRD2/3 knockout by CRISPR/Cas9 in patient-derived human GBMTSs inhibited cell growth and ATP production.The combined treatment with PER andTMZ resulted in superior effects on cell viability and ATP assays compared to those in single treatment groups. Flow cytometry, western blotting, and RNA sequencing confirmed elevated apoptosis in GBMTSs following combination treatment. Additionally, the combination of PER andTMZ downregulated the expression of protein and mRNA associated with stemness and invasiveness. In vivo evaluation showed that combining PER andTMZ extended the survival period of the mouse orthotopic xenograft model. Conclusions. The synergistic combination of PER andTMZ has potential as a novel combination treatment strategy for GBM.