BH3 Profiling Identifies Apoptotic Priming by SREBP-1/-2 Inhibition and Synergistic Anti-Glioblastoma Activity When Combined with ABT-263 In Vitro

Background/Objectives: Glioblastoma exhibits profound therapy resistance driven in part by complex pro-survival signaling. We hypothesized that targeting lipid metabolism via SREBP-1/2 inhibition (fatostatin) might alter the apoptotic phenotype and facilitate an apoptotic response driven by BH3 mimetics (ABT-263) in glioblastoma in vitro. Methods: Dynamic BH3 profiling was performed to detect apoptotic priming. The combined inhibition of SREBP-1/2 and Bcl-xL/Bcl-2 was evaluated across 2- and 3-dimensional culture models. The cell lines used included established cell lines as well as primary cultures and glioma stem-like cells. Extracellular flux analysis was used to assess metabolic effects. Changes in migration were evaluated through time-lapse analysis, scratch, and Transwell assays. Results: BH3 profiling showed that treatment with fatostatin increased Bcl-xL/Bcl-2 reliance, while ABT-263 increased Mcl-1 dependence. The combination showed potent synergy in inhibiting viability and spheroid growth, driven at least in part by enhanced caspase-dependent apoptosis. Mechanistically, fatostatin induced dose-dependent Mcl-1 downregulation, sensitizing cells to ABT-263. Dual treatment suppressed oxidative phosphorylation and impaired cell migration, while exhibiting low toxicity in non-pathological cells. Conclusions: This study indicates that combined inhibition of SREBP-1/2 and Bcl-xL/Bcl-2 represents a promising therapeutic strategy for the treatment of glioblastoma. The efficacy of this dual approach potentially lies in the downregulation of Mcl-1 induced by fatostatin and suppression of oxidative phosphorylation. Further studies are warranted.