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Glioblastomas (GBM) are the most lethal central nervous system (CNS) tumors, mainly due to their high heterogeneity, invasiveness, and proliferation rate. These tumors remain a therapeutic challenge, and there are still some gaps in the GBM biology knowledge. Despite the significant amount of knowledge produced by research on cancer metabolism, its implementation in cancer treatment has been limited. Nevertheless, glutamine plays a key role in CNS metabolism, and metabolic adjustments have been reported in several CNS malignancies, including GBM, which are considered glutamine addicted. This suggests glutamine metabolism as a putative target for CNS cancer treatment. Therefore, our goal was to design a glutaminase 1 (GLS1)-based systemic therapy in order to take advantage of GBM reliance on glutamine. Thus, overcoming the blood-brain barrier and making GBM therapy more effective. The effect of GLS1 on GBM cell lines viability was assessed by annexin V / propidium iodide staining and flow cytometry analysis. The effect on cell proliferation was assessed by WST-1 assay. qPCR was used to analyze the gene expression profiles upon GLS1 exposure. NSG (NOD.Cg-Prkdcscid Il2rgtm1Wjl / SzJ)mice were used for an orthotopic xenograft mouse model of GBM, approved by the national ethical committee (Direção Geral de Alimentação e Veterinária, Portugal; ref 8516) performed in accordance with the European Union Directive 2010 / 63 / EU. 1H-NMR was used to analyze the effect of GLS1 on GBM cells metabolic profile and the metabolic profiles of mice sera during the in vivo experiments. The in vitro results showed that GLS1 induces an adjustment of metabolic gene expression in GBM cell lines, mainly increasing fatty acids metabolism-related genes, while decreasing the expression of genes related to glutamine and glutamate uptake, even though the cell lines used showed differences at glycolysis. Preliminary 1H-NMR results also showed differences in metabolites involved in glutaminolysis. Moreover, GLS1 induced increased cell death and decreased cell proliferation. Preliminary results from our orthotopic mouse model of GBM showed an increase in overall survival with the GLS1 treatment. Moreover, multivariate analysis of metabolomics of serum collected from control and GLS1-treated mice groups, during the therapy course, show statistically different metabolic profiles midst treatment. This could help monitoring the therapy-response, making GLS1 an interesting new therapy. Therefore, we propose GLS1 systemic conditioning as a new therapeutic modality in GBM. This is the first attempt to affect GBM cancer cells by targeting GBM metabolic needs for glutamine and taking advantage of their inefficacy of synthesizing glutamine. With this in mind, we have already protected this idea with a patent: Glutaminase, Methods and Uses Thereof; National Patent Nº PT118918, priority date 14 / 09 / 2023. The institutions are funded by Fundação para a Ciência e a Tecnologia / Ministério da Ciência, Tecnologia e Ensino Superior through national funds (PTDC / MEDQUI / 3542 / 2020). Filipa Martins was funded by an FCT individual Ph.D. fellowship (2020.04780.BD). Access to CERMAX, ITQB-NOVA, Oeiras, Portugal with equipment funded by FCT, project AAC 01 / SAICT / 2016.
Martins et al. (Fri,) studied this question.