Publicação
Targeting glutamine availability : a new strategy to treat malignant gliomas
| Resumo: | Glioblastoma (GBM), the most aggressive and lethal Central Nervous System (CNS) malignancy, poses significant therapeutic challenges due to its high genetic and metabolic heterogeneity, invasiveness, and the protective nature of the blood-brain barrier (BBB). GBM patients face a median overall survival (OS) of only 8 months following diagnosis, since disease progression and relapse are very common. There are still some gaps in the GBM biology knowledge, and the better understanding of GBM metabolic remodeling can allow the implementation of new therapeutic strategies. Utilizing transcriptomics data from The Cancer Genome Atlas (TCGA) database, we identified metabolism-related patterns that could inform clinical applications, such as the discovery of new biomarkers and putative therapeutic targets for drug development. Our in vitro findings indicate that GBM cell lines U251 and U-87MG adapt to various organic compounds (glucose, lactate, glutamine, and glutamate), demonstrating their metabolic flexibility. These cells fulfill glycolysis in the presence of glucose and are capable of producing and consuming lactate. Importantly, glutamine dependence was highlighted, with glutamine and glutamate availability favoring biosynthesis pathways, as observed by increased expression of genes involved in fatty acid synthesis. These results underscore the informative power of metabolism and the importance of metabolic profiling in personalizing GBM treatment. Glutamine metabolism is essential for GBM cell survival and tumor growth. Indeed, GBM is considered glutamine addicted, since the metabolic remodeling that occurs involves the abrogation of glutamine synthetase (GS) and increased expression of glutamine transporters. Current strategies targeting glutamine metabolism have proven difficult to clinically implement due to adverse effects, the BBB hurdle, and the complexity of brain tumor biology. This study hypothesizes that exploiting GBM glutamine dependence is a viable treatment strategy and proposes two approaches: a systemic glutaminase (GLS1) treatment and a targeted theranostics approach using polyurea dendrimers generation four (PUREG4) functionalized with lactate (to target monocarboxylate transporter 1, MCT1) to deliver small interfering RNAs (siRNAs) anti-GLS1 across the BBB into the tumor. Systemic GLS1 treatment has the advantage that it does not need to cross the BBB, affecting only the GBM cells since the other cells retain the ability to synthetize glutamine. GLS1-therapy can effectively reduce glutamine availability, impairing GBM cell metabolism and survival. This therapy was validated in a GBM orthotopic xenograft murine model, inducing increased OS and delayed cachexia. Metabolomic analysis of serum collected during tumor induction and treatment revealed statistically significant differences in metabolic profiles of GLS1-treated mice, suggesting that these profiles could be used to monitor therapeutic response. Additionally, we explored a theranostics approach using polyurea dendrimers. PUREG4-LA24 dendrimers were able to efficiently deliver cytotoxic drugs (selenium-chrysin – SeChry and temozolomide –TMZ) to GBM cells and induce cell death, with higher impact in U251 cell line, since it has higher MCT1 expression. The viability of b.End3, the cell line used as a BBB model, was also affected by SeChry, suggesting induction of BBB disruption, which can benefit drug delivery. To affect the glutamine metabolism, we tested an anti-GLS1 siRNA. Knockdown of GLS1 with siRNA induced cell death, while affecting the metabolism of GBM cell lines. Therefore, we formed the dendriplexes PUREG4-LA12-siRNA anti-GLS1, which efficiently knockdown GLS1 expression when cells were directly exposed. Moreover, this dendriplex successfully crossed an in vitro BBB model, altering GBM cell lines exometabolome. Further studies are warranted to validate these results in vivo and to explore the combinatory potential of this approach with existing GBM therapies. Our findings highlight the potential of targeting glutamine metabolism in GBM, presenting two different metabolism-based strategies to impair GBM metabolism and survival. This approach offers a novel and promising direction for GBM therapy, emphasizing the importance of personalized metabolic profiling and metabolism-targeted interventions to enhance clinical outcomes. |
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| Autores principais: | Martins, Filipa |
| Assunto: | Glioblastoma (GBM) Cancer metabolism Metabolic remodeling Glutamine reliance Glutaminase (GLS1) Systemic therapy Targeted therapy Blood-brain barrier (BBB) Polyurea dendrimer generation 4 functionalized with lactate (PUREG4-LA12) PUREG4-LA12-siRNA dendriplex Metabolism-based therapy |
| Ano: | 2024 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso embargado |
| Instituição associada: | Universidade Nova de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório Institucional da UNL |
| Resumo: | Glioblastoma (GBM), the most aggressive and lethal Central Nervous System (CNS) malignancy, poses significant therapeutic challenges due to its high genetic and metabolic heterogeneity, invasiveness, and the protective nature of the blood-brain barrier (BBB). GBM patients face a median overall survival (OS) of only 8 months following diagnosis, since disease progression and relapse are very common. There are still some gaps in the GBM biology knowledge, and the better understanding of GBM metabolic remodeling can allow the implementation of new therapeutic strategies. Utilizing transcriptomics data from The Cancer Genome Atlas (TCGA) database, we identified metabolism-related patterns that could inform clinical applications, such as the discovery of new biomarkers and putative therapeutic targets for drug development. Our in vitro findings indicate that GBM cell lines U251 and U-87MG adapt to various organic compounds (glucose, lactate, glutamine, and glutamate), demonstrating their metabolic flexibility. These cells fulfill glycolysis in the presence of glucose and are capable of producing and consuming lactate. Importantly, glutamine dependence was highlighted, with glutamine and glutamate availability favoring biosynthesis pathways, as observed by increased expression of genes involved in fatty acid synthesis. These results underscore the informative power of metabolism and the importance of metabolic profiling in personalizing GBM treatment. Glutamine metabolism is essential for GBM cell survival and tumor growth. Indeed, GBM is considered glutamine addicted, since the metabolic remodeling that occurs involves the abrogation of glutamine synthetase (GS) and increased expression of glutamine transporters. Current strategies targeting glutamine metabolism have proven difficult to clinically implement due to adverse effects, the BBB hurdle, and the complexity of brain tumor biology. This study hypothesizes that exploiting GBM glutamine dependence is a viable treatment strategy and proposes two approaches: a systemic glutaminase (GLS1) treatment and a targeted theranostics approach using polyurea dendrimers generation four (PUREG4) functionalized with lactate (to target monocarboxylate transporter 1, MCT1) to deliver small interfering RNAs (siRNAs) anti-GLS1 across the BBB into the tumor. Systemic GLS1 treatment has the advantage that it does not need to cross the BBB, affecting only the GBM cells since the other cells retain the ability to synthetize glutamine. GLS1-therapy can effectively reduce glutamine availability, impairing GBM cell metabolism and survival. This therapy was validated in a GBM orthotopic xenograft murine model, inducing increased OS and delayed cachexia. Metabolomic analysis of serum collected during tumor induction and treatment revealed statistically significant differences in metabolic profiles of GLS1-treated mice, suggesting that these profiles could be used to monitor therapeutic response. Additionally, we explored a theranostics approach using polyurea dendrimers. PUREG4-LA24 dendrimers were able to efficiently deliver cytotoxic drugs (selenium-chrysin – SeChry and temozolomide –TMZ) to GBM cells and induce cell death, with higher impact in U251 cell line, since it has higher MCT1 expression. The viability of b.End3, the cell line used as a BBB model, was also affected by SeChry, suggesting induction of BBB disruption, which can benefit drug delivery. To affect the glutamine metabolism, we tested an anti-GLS1 siRNA. Knockdown of GLS1 with siRNA induced cell death, while affecting the metabolism of GBM cell lines. Therefore, we formed the dendriplexes PUREG4-LA12-siRNA anti-GLS1, which efficiently knockdown GLS1 expression when cells were directly exposed. Moreover, this dendriplex successfully crossed an in vitro BBB model, altering GBM cell lines exometabolome. Further studies are warranted to validate these results in vivo and to explore the combinatory potential of this approach with existing GBM therapies. Our findings highlight the potential of targeting glutamine metabolism in GBM, presenting two different metabolism-based strategies to impair GBM metabolism and survival. This approach offers a novel and promising direction for GBM therapy, emphasizing the importance of personalized metabolic profiling and metabolism-targeted interventions to enhance clinical outcomes. |
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