Article
Combined inhibition of Bcl-xL/Bcl-2 and SREBP-1 results in a synergistic anti-neoplastic activity in glioblastoma cells in vitro
Die kombinierte Hemmung von Bcl-xL/Bcl-2 und SREBP-1 führt zu einer synergistischen anti-neoplastischen Aktivität im Glioblastom in vitro
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Published: | May 25, 2022 |
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Objective: A cellular homeostasis that is shifted away from apoptosis and a reprogramming of the lipid metabolism are both, features that are frequently encountered in glioblastoma. This study aimed at investigating whether a combined reprogramming of the apoptotic machinery and the lipid metabolism results in a synergistic anti-glioblastoma activity in vitro.
Methods: Established (U251) and primary-cultured glioblastoma cells (PC38, PC40 and PC128) as well as glioblastoma stem-like cells (SC38 and SC40) were treated with the Bcl-xL/Bcl-2 inhibitor ABT-263 (navitoclax) and/or the SREBP-1 inhibitor Fatostatin. MTT-assays were performed to assess effects of the combination therapy on the cell viability. Isobolograms were calculated to characterize the nature of the drug-drug interaction. Spheroids were used to determine anti-proliferative effects in a 3-dimensional setting. Staining with annexin V/propidium iodide and flowcytometric analysis were performed to assess pro-apoptotic effects. For molecular analyses, Western blots and specific knock-down experiments with siRNA were performed.
Results: A simultaneous treatment with ABT-263 and Fatostatin resulted in a synergistic anti-proliferative effect on established, primary-cultured and glioblastoma stem-like cells as well as spheroids. The prevailing form of cell death after combined treatment with ABT-263 and Fatostatin was shown to be apoptosis, which occurred in a caspase-dependent manner. On the molecular level, treatment with increasing concentrations of Fatostatin led to a downregulation of Mcl-1 in a dose-dependent manner.
Conclusion: Our study indicates that combined inhibition of Bcl-xL/Bcl-2 and interference with the lipid metabolism targeting SREBP-1 synergistically induces caspase-dependent apoptosis in glioblastoma cells. This effect can also be observed in more complex 3-dimensional glioblastoma cell formations. Further studies will focus on deciphering the drug-induced alterations of the metabolic pathways that are responsible for the synergistic effect of this therapeutic strategy.