Downregulation of Glutamine Synthetase, not glutaminolysis, is responsible for glutamine addiction in Notch1-driven acute lymphoblastic leukemia

The cellular receptor Notch1 is a central regulator of T-cell development, and as a consequence, Notch1 pathway appears upregulated in > 65% of the cases of T-cell acute lymphoblastic leukemia (T-ALL). However, strategies targeting Notch1 signaling render only modest results in the clinic due to treatment resistance and severe side effects. While many investigations reported the different aspects of tumor cell growth and leukemia progression controlled by Notch1, less is known regarding the modifications of cellular metabolism induced by Notch1 upregulation in T-ALL. Previously, glutaminolysis inhibition has been proposed to synergize with anti-Notch therapies in T-ALL models. In this work, we report that Notch1 upregulation in T-ALL induced a change in the metabolism of the important amino acid glutamine, preventing glutamine synthesis through the downregulation of glutamine synthetase (GS). Downregulation of GS was responsible for glutamine addiction in Notch1-driven T-ALL both in vitro and in vivo. Our results also confirmed an increase in glutaminolysis mediated by Notch1. Increased glutaminolysis resulted in the activation of the mammalian target of rapamycin complex 1 (mTORC1) pathway, a central controller of cell growth. However, glutaminolysis did not play any role in Notch1-induced glutamine addiction. Finally, the combined treatment targeting mTORC1 and limiting glutamine availability had a synergistic effect to induce apoptosis and to prevent Notch1-driven leukemia progression. Our results placed glutamine limitation and mTORC1 inhibition as a potential therapy against Notch1-driven leukemia.This work was supported by funds from the followinginstitutions: Agencia Estatal de Investigacion/Euro-pean Regional Development Fund, European Union(PGC2018-096244-B-I00, SAF2016-75442-R), Ministryof Science, Innovation and Universities of Spain,Spanish National Research Council—CSIC, InstitutNational de la Sante et de la Recherche Medicale—INSERM, Ligue Contre le Cancer—Gironde, Univer-site de Bordeaux, Fondation pour la Recherche Medi-cale, the Conseil Regional d’Aquitaine, SIRIC-BRIO,Fondation ARC and Institut Europeen de Chimie etBiologie. MJN was supported by a bourse d’excellencede la Federation Wallonie-Bruxelles (WBI) and a post-doctoral fellowship from Fondation ARC. We thankVincent Pitard (Flow Cytometry Platform, Universitede Bordeaux, France) for technical assistance in flowcytometry experiments. We thank Diana Cabrera(Metabolomics Platform, CIC bioGUNE, Spain) fortechnical assistance in metabolomics analysi

Downregulation of Glutamine Synthetase, not glutaminolysis, is responsible for glutamine addiction in Notch1-driven acute lymphoblastic leukemia

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Orientational Effects and Random Mixing in 1-Alkanol + Alkanone Mixtures

1-Alkanol + alkanone systems have been investigated through the data analysis of molar excess functions, enthalpies, isobaric heat capacities, volumes and entropies, and using the Flory model and the formalism of the concentrationconcentration structure factor (SCC(0)). The enthalpy of the hydroxyl-carbonyl interactions has been evaluated. These interactions are stronger in mixtures with shorter alcohols (methanol-1-butanol) and 2-propanone or 2-butanone. However, effects related to the self-association of alcohols and to solvation between unlike molecules are of minor importance when compared with those which arise from dipolar interactions. Physical interactions are more relevant in mixtures with longer 1-alkanols. The studied systems are characterized by large structural effects. The variation of the molar excess enthalpy with the alcohol size along systems with a given ketone or with the alkanone size in solutions with a given alcohol are discussed in terms of the different contributions to this excess function. Mixtures with methanol show rather large orientational effects. The random mixing hypothesis is attained to a large extent for mixtures with 1-alkanols ≠ methanol and 2-alkanones. Steric effects and cyclization lead to stronger orientational effects in mixtures with 3-pentanone, 4-heptanone, or cyclohexanone. The increase of temperature weakens orientational effects. Results from SCC(0) calculations show that homocoordination is predominant and support conclusions obtained from the Flory model.Ministerio de Ciencia e Innovación, under Project FIS2010-1695

Downregulation of Glutamine Synthetase, not glutaminolysis, is responsible for glutamine addiction in Notch1-driven acute lymphoblastic leukemia

The cellular receptor Notch1 is a central regulator of T-cell development, and as a consequence, Notch1 pathway appears upregulated in > 65% of the cases of T-cell acute lymphoblastic leukemia (T-ALL). However, strategies targeting Notch1 signaling render only modest results in the clinic due to treatment resistance and severe side effects. While many investigations reported the different aspects of tumor cell growth and leukemia progression controlled by Notch1, less is known regarding the modifications of cellular metabolism induced by Notch1 upregulation in T-ALL. Previously, glutaminolysis inhibition has been proposed to synergize with anti-Notch therapies in T-ALL models. In this work, we report that Notch1 upregulation in T-ALL induced a change in the metabolism of the important amino acid glutamine, preventing glutamine synthesis through the downregulation of glutamine synthetase (GS). Downregulation of GS was responsible for glutamine addiction in Notch1-driven T-ALL both in vitro and in vivo. Our results also confirmed an increase in glutaminolysis mediated by Notch1. Increased glutaminolysis resulted in the activation of the mammalian target of rapamycin complex 1 (mTORC1) pathway, a central controller of cell growth. However, glutaminolysis did not play any role in Notch1-induced glutamine addiction. Finally, the combined treatment targeting mTORC1 and limiting glutamine availability had a synergistic effect to induce apoptosis and to prevent Notch1-driven leukemia progression. Our results placed glutamine limitation and mTORC1 inhibition as a potential therapy against Notch1-driven leukemia.This work was supported by funds from the following institutions: Agencia Estatal de Investigación/European Regional Development Fund, European Union (PGC2018-096244-B-I00, SAF2016-75442-R), Ministry of Science, Innovation and Universities of Spain, Spanish National Research Council—CSIC, Institut National de la Santé et de la Recherche Médicale—INSERM, Ligue Contre le Cancer—Gironde, Université de Bordeaux, Fondation pour la Recherche Médicale, the Conseil Régional d'Aquitaine, SIRIC-BRIO, Fondation ARC and Institut Européen de Chimie et Biologie. MJN was supported by a bourse d’excellence de la Fédération Wallonie-Bruxelles (WBI) and a postdoctoral fellowship from Fondation ARC. We thank Vincent Pitard (Flow Cytometry Platform, Université de Bordeaux, France) for technical assistance in flow cytometry experiments. We thank Diana Cabrera (Metabolomics Platform, CIC bioGUNE, Spain) for technical assistance in metabolomics analysis.Ye