P01.44.B AMPK INHIBITION SYNERGISTICALLY ENHANCES THE EFFECT OF FATOSTATIN-TREATMENT IN GLIOBLASTOMA CELL MODELS

Abstract BACKGROUND The ability to reprogram the energy metabolism is considered a hallmark of cancer cells to meet the increased energy demands essential for proliferation and cell growth. However, little is known on the effectiveness of targeting key regulators of metabolic disorders in glioblastoma cells. Therefore, we aimed to investigate the impact of AMP-activated protein kinase (AMPK)- and SREBP-inhibition by dorsomorphin and fatostatin on the expression of enzymes controlling de novo fatty acid synthesis (e.g.FASN) in glioblastoma (GB) cells in vitro. MATERIAL AND METHODS Patient derived cell models (n=52) established from freshly resected GB tissue were analysed for FASN expression by qRT-PCR and sensitivity against the SREBP-inhibitor fatostatin. Out of these, three cell models (T98G/BTL761/BTL53) representative for high/medium/low FASN expression were selected for further analysis. Drug-sensitivity against both, the AMPK and SREBP inhibitors dorsomorphin and fatostatin was tested using an MTT-based approach. The effect of lipogenesis inhibition on the expression of AMPK, phospho-AMPK and SREBP effector proteins (e.g. FASN, ACC) was investigated following drug treatment by Western blot. RESULTS In our GB cell models FASN mRNA was found to be expressed at varying levels, but was significantly higher as compared to human normal astrocytes. Additionally, high FASN mRNA expression was significantly associated with higher sensitivity against SREBP inhibition by fatostatin (p=0.0352). With respect to the selected cell models, the FASNlow expressing BTL53 cell model presented with modest response against fatostatin, but high sensitivity against the AMPK-inhibitor dorsomorphin. Interestingly, this was in contrast to the FASNhigh expressing BTL761 and T98G cells, which showed high sensitivity against fatostatin but were distinctly lower susceptible to dorsomorphin treatment. Interestingly, combined drug treatment resulted in a synergistically enhanced effect, which was irrespective of the extent of the initial FASN expression level. CONCLUSION GB cells presenting with high levels of FASN are susceptible to fatostatin treatment, which was indicated by IC50 levels below 20µM. Combined treatment with inhibitors directed against both, the AMPK and SREBP pathway resulted in a synergistically enhanced response. Consequently, lipogenesis inhibition by attacking different axes of metabolism regulation might be a promising novel therapeutic option in glioblastoma. The effect of drug combinations on the expression of proteins involved in de novo lipogenesis will be analysed in further studies.