A 29-gene signature associated with NOX2 discriminates acute myeloid leukemia prognosis and survival

Fuente editorial: Wiley [Commercial Publisher] (American Journal of Hematology)[EN] The molecular complexity displayed in acute myeloid leukemia (AML) hinders patient stratification and treatment decisions. Previous studies support the utility of using specific gene panels for this purpose. Focusing on two salient features of AML, the production of reactive oxygen species (ROS) by NADPH oxidases (NOX) and metabolism, we aimed to identify a gene panel that could improve patient stratification. A pairwise comparison of AML versus healthy gene expression revealed the downregulation of four members of the NOX2 complex including CYBB (coding for NOX2) in AML patients. We analyzed the expression of 941 genes related to metabolism and found 28 genes with expression correlated to CYBB. This panel of 29 genes (29G) effectively divides AML samples according to their prognostic group. The robustness of 29G was confirmed by 6 AML cohort datasets with a total of 1821 patients (overall accuracies of 85%, 78%, 80%, 75%, 59% and 83%). An expression index (EI) was developed according to the expression of the selected discriminatory genes. Overall Survival (OS) was higher for low 29G expression index patients than for the high 29G expression index group, which was confirmed in three different datasets with a total of 1069 patients. Moreover, 29G can dissect intermediate-prognosis patients in four clusters with different OS, which could improve the current AML stratification scheme. In summary, we have found a gene signature (29G) that can be used for AML classification and for OS prediction. Our results confirm NOX and metabolism as suitable therapeutic targets in AML.This work was supported by the Regional Government of Castile & Leon (SA077P20) and by the Spanish Government (PID2020-117692RB-I00) grants received by Dr Hernández-Hernández. Carla Ijurko was the recipient of pre-doctoral fellowships from the Regional Government of Castile and Leon, Spain and ERDF funds

Reactive oxygen species in haematopoiesis: leukaemic cells take a walk on the wild side

[EN]Oxidative stress is related to ageing and degenerative diseases, including cancer. However, a moderate amount of reactive oxygen species (ROS) is required for the regulation of cellular signalling and gene expression. A low level of ROS is important for maintaining quiescence and the differentiation potential of haematopoietic stem cells (HSCs), whereas the level of ROS increases during haematopoietic differentiation; thus, suggesting the importance of redox signalling in haematopoiesis. Here, we will analyse the importance of ROS for haematopoiesis and include evidence showing that cells from leukaemia patients live under oxidative stress. The potential sources of ROS will be described. Finally, the level of oxidative stress in leukaemic cells can also be harnessed for therapeutic purposes. In this regard, the reliance of front-line anti-leukaemia chemotherapeutics on increased levels of ROS for their mechanism of action, as well as the active search for novel compounds that modulate the redox state of leukaemic cells, will be analysed

NOX2 and its effect on metabolism, new targets for prognosis and treatment of acute myeloid leukemia

[ES] La leucemia mieloide aguda (LMA) es la leucemia más diagnosticada en adultos. Su abordaje clínico es complejo debido, principalmente, a su gran heterogeneidad. Esto ha ocasionado que durante más de 50 años apenas se hayan introducido mejoras en su diagnóstico y tratamiento. Sin embargo, la revolución de las ciencias ómicas ha provocado que en los últimos 4 años el protocolo médico de diagnóstico, pronóstico y tratamiento de la enfermedad se haya visto notablemente modificado. La reciente inclusión de varias mutaciones en la determinación pronóstica y la aprobación de hasta nueve nuevos agentes terapéuticos denota que la gestión clínica de la LMA está cambiando y que este tema es de actualidad. Pese a ello, la supervivencia a 5 años de la enfermedad sigue siendo inferior al 30%. Dos mecanismos moleculares, el metabolismo y la señalización redox, han demostrado estar involucrados en la hematopoyesis normal y en su versión tumorigénica, la leucemogénesis. Además, estos dos procesos se encuentran interconectados. Las especies reactivas del oxígeno (ROS), principales ejecutoras de la señalización redox, regulan el metabolismo; y este es el mayor productor de ROS. Con todo, los mecanismos que gobiernan esta relación redox-metabolismo requieren una investigación más profunda. En este sentido, destacan las NADPH oxidasas (NOX) por ser el único sistema celular cuya funcionalidad principal es la producción de ROS y, por tanto, tentativamente ser las enzimas clave para regular la señalización redox. En esta tesis estudiamos el papel de NOX2 en la LMA. NOX2 es el miembro de la familia de las NOX mayoritariamente expresado en células mieloides. Hemos descubierto que NOX2 tiene un papel importante regulando el metabolismo de la glucosa de células leucémicas, de modo que el descenso de los niveles de NOX2 provoca un metabolismo mitocondrial deficiente (ciclo de los ácidos tricarboxílicos y fosforilación oxidativa disminuidos), que puede ser compensado por un incremento glucolítico en células metabólicamente flexibles. Además, hemos visto que NOX2 también tiene un rol importante en la regulación del sistema glutation, donde bajos niveles de NOX2 se ven acompañados de un descenso en los niveles de glutation y una capacidad antioxidante comprometida. Así pues, NOX2 resulta fundamental para mantener un metabolismo mitocondrial activo y permitir la reposición de los depósitos de glutation en células de LMA. Conocer estas interacciones moleculares, nos permite proponer un tratamiento de inhibición de las NOX (iNOX) en combinación con inhibidores del metabolismo de la glucosa como estrategia terapéutica frente a la LMA. Esta combinación ha resultado eficaz en líneas celulares y células procedentes de pacientes con distinto fondo genético molecular. De entre las alternativas testadas, la inhibición de NOX junto con el tratamiento con oxamato (Ox) ha resultado la opción más atractiva por su alta efectividad y su moderada toxicidad en células sanas de médula ósea. La efectividad de iNOX+Ox es mayor cuanto más alta es la expresión de NOX2. Por ello, iNOX+Ox se muestra una alternativa interesante para pacientes con altos niveles de NOX2 como aquellos con fenotipo diferenciado, grupos FAB (clasificación French-American-British) M4 o M5, y quimiorresistentes. La adición de citarabina (Ara-C) a la combinación iNOX+Ox aumenta la potencia de la combinación induciendo más fuertemente la muerte celular. Según nuestros datos, la efectividad de la combinación parece deberse a la modulación que ejerce sobre el metabolismo energético y a una potente supresión de la capacidad antioxidante de la célula. Por último, en esta tesis presentamos un panel de 29 genes correlacionados (29G) con implicación en el metabolismo, entre los que se encuentra NOX2. Este panel tiene capacidad de clasificar a nivel pronóstico a los pacientes de LMA. Un paso más allá, la expresión de estos 29 genes nos ha permitido computar un índice que podría predecir la supervivencia de los pacientes en base a 29G. 29G también discrimina 4 grupos con distinta supervivencia dentro del grupo de pacientes con pronóstico intermedio. 29G podría mejorar la clasificación de un grupo tan heterogéneo como es el de pronóstico intermedio, que actualmente concentra a todos aquellos casos con alteraciones que no han sido catalogadas como favorables o adversas. Todos estos resultados coinciden en NOX2 y su influencia sobre el metabolismo como piezas angulares de la LMA. [EN] AML is the most commonly diagnosed leukemia in adults. Its clinical management is complex, mainly due to its great heterogeneity. Consequently, for more than 50 years there has been little improvement in its diagnosis and treatment. However, in the last 4 years the medical protocol for diagnosis, prognosis and treatment of the disease has been significantly modified owing to the revolution in the omics sciences. The recent inclusion of several mutations in the prognostic determination and the approval of nine new therapeutic agents indicate that the clinical management of AML is changing and that AML is a hot topic. Notwithstanding, the 5-year survival of the disease is still less than 30%. Two molecular mechanisms, metabolism and redox signaling, have been shown to be involved in normal hematopoiesis and its tumorigenic version, leukemogenesis. Moreover, these two processes are interconnected. Reactive oxygen species (ROS), the main executors of redox signaling, are involved in metabolic regulation and metabolism is the major producer of ROS. However, the mechanisms governing this redox metabolism relationship require further investigation. In this sense, NOX stand out as the only cellular system whose main functionality is the production of ROS and, therefore, tentatively as the key enzymes to regulate redox signaling and, further, its influence on metabolism. In this thesis we study the role of NOX2 in AML. NOX2 is the NOX family member mostly expressed in myeloid cells. We have found that NOX2 plays an important role in regulating glucose metabolism of leukemic cells. Decreased NOX2 levels lead to impaired mitochondrial metabolism (decreased tricarboxylic acid cycle and oxidative phosphorylation), which can be compensated by a glycolytic increase in metabolically flexible cells. In addition, we have shown that NOX2 also plays an important role in the regulation of the glutathione system, where low NOX2 levels are accompanied by decreased glutathione levels and compromised antioxidant capacity. Thus, NOX2 is critical for maintaining active mitochondrial metabolism and allowing replenishment of glutathione stores in AML cells. Knowledge of these molecular interactions allows us to propose a NOX inhibition (iNOX) treatment in combination with glucose metabolism inhibition as a therapeutic strategy against AML. This combination has been effective in cell lines and patients’ bone marrow mononuclear cells with different molecular-genetic backgrounds. Among the alternatives tested, NOX inhibition together with oxamate (Ox) treatment has proved to be the most attractive option due to its high effectiveness against tumoral cells and moderate toxicity in healthy bone marrow cells. iNOX+Ox shows greater effectiveness the higher the NOX2 expression. Thus, iNOX+Ox is an interesting alternative for FAB group patients with a differentiated phenotype, M4 or M5, and chemoresistant patients who have demonstrated high NOX2 expression. The addition of cytarabine (Ara-C) to the iNOX+Ox combination increases the potency of the combination by more strongly inducing cell death. Furthermore, according to our data, the effectiveness of the combination seems to be due to the modulation on energy metabolism and a potent suppression of antioxidant capacity exerted on cells. Finally, in this thesis we present a panel of 29 correlated genes (29G), including NOX2 and involved in metabolism, with the ability to prognostically classify AML patients. One step further, the expression of these 29 genes has allowed us to compute an index that could predict patient survival based on 29G. 29G also discriminates 4 groups with different survival rates within the group of patients with intermediate prognosis. 29G could improve the classification of such a heterogeneous group as the intermediate prognosis group, which currently concentrates all those cases with alterations that have not been classified as favorable or adverse. All these results coincide in NOX2 and its influence on metabolism as cornerstones of AML