Oxidative Phosphorylation Fueled by Fatty Acid Oxidation Sensitizes Leukemic Stem Cells to Cold

Dependency on mitochondrial oxidative phosphorylation (OxPhos) is a potential weakness for leukemic stem cells (LSC) that can be exploited for therapeutic purposes. Fatty acid oxidation (FAO) is a crucial OxPhos-fueling catabolic pathway for some acute myeloid leukemia (AML) cells, particularly chemotherapy-resistant AML cells. Here, we identified cold sensitivity at 4◦C (cold killing challenge; CKC4), commonly used for sample storage, as a novel vulnerability that selectively kills AML LSCs with active FAO-supported OxPhos while sparing normal hematopoietic stem cells. Cell death of OxPhos-positive leukemic cells was induced by membrane permeabilization at 4◦C; by sharp contrast, leukemic cells relying on glycolysis were resistant. Forcing glycolytic cells to activate OxPhos metabolism sensitized them to CKC4. Lipidomic and proteomic analyses showed that OxPhos shapes the composition of the plasma membrane and introduces variation of 22 lipid subfamilies between cold-sensitive and cold-resistant cells. Together, these findings indicate that steady-state energy metabolism at body temperature predetermines the sensitivity of AML LSCs to cold temperature, suggesting that cold sensitivity could be a potential OxPhos biomarker. These results could have important implications for designing experiments for AML research to avoid cell storage at 4◦C.</p

Characterization of human DNGR-1+ BDCA3+ leukocytes as putative equivalents of mouse CD8α+ dendritic cells

In mouse, a subset of dendritic cells (DCs) known as CD8α+ DCs has emerged as an important player in the regulation of T cell responses and a promising target in vaccination strategies. However, translation into clinical protocols has been hampered by the failure to identify CD8α+ DCs in humans. Here, we characterize a population of human DCs that expresses DNGR-1 (CLEC9A) and high levels of BDCA3 and resembles mouse CD8α+ DCs in phenotype and function. We describe the presence of such cells in the spleens of humans and humanized mice and report on a protocol to generate them in vitro. Like mouse CD8α+ DCs, human DNGR-1+ BDCA3hi DCs express Necl2, CD207, BATF3, IRF8, and TLR3, but not CD11b, IRF4, TLR7, or (unlike CD8α+ DCs) TLR9. DNGR-1+ BDCA3hi DCs respond to poly I:C and agonists of TLR8, but not of TLR7, and produce interleukin (IL)-12 when given innate and T cell–derived signals. Notably, DNGR-1+ BDCA3+ DCs from in vitro cultures efficiently internalize material from dead cells and can cross-present exogenous antigens to CD8+ T cells upon treatment with poly I:C. The characterization of human DNGR-1+ BDCA3hi DCs and the ability to grow them in vitro opens the door for exploiting this subset in immunotherapy

Évaluation préclinique du potentiel thérapeutique d'un inhibiteur de IKK2 et de FLT3 dans le traitement des leucémies aiguës myéloïdes

Fms Like Tyrosine Kinase 3 (FLT3) est le gène le plus fréquemment muté de la Leucémie Aiguë Myéloïde. Ces mutations entraînent une activation constitutive de FLT3. A l aide de lignées porteuses des formes sauvages ou mutantes de FLT3, nous avons montré que l activation normale ou oncogénique de FLT3 activait la voie NF-kB. De façon inattendue, nous avons découvert au cours de cette étude que l inhibiteur de IKK2 AS602868 puisqu il cible deux kinases cruciales pour la pathogénèse de la LAM. Dans le but d évaluer le potentiel thérapeutique de AS602868, nous avons comparé l effet de la molécule dans différentes étapes des processus hématopoïétiques et leucémiques. Au cours d expériences in vitro et in vivo nous avons mis en évidence un ciblage pharmacologique préférentiel de la population souche-progénitrice leucémique. Un traitement identique à celui administré aux échantillons de patients a peu ou pas d effets délétères sur l hématopoïèse normale. Nous montrons pour la première fois le ciblage préférentiel in vivo des CSL par un inhibiteur de IKK2. Les résultats de notre recherche permettent d établir que la signalisation normale ou oncogénique de FLT3 peut être la cause de l activation constitutive anormale de la voie de transcription NF-kB observée dans la LAM. Notre étude identifie une nouvelle cible de l inhibiteur de IKK2 et renforce la perspective d utilisation de AS602868 en essai clinique. Pour finir, ce travail de thèse suggère que le ciblage pharmacologique in vivo de cellules souches leucémiques doit être le but recherché des nouvelles thérapies de la LAM.Fms Like Tyrosine Kinase 3 (FLT3) is the most frequently mutated gene in LAM. Its mutations lead to a constitutive activation of FLT3 which constitute a proliferation and survival advantage for leukemic cells. Using cell lines carrying wild type or mutated forms of FLT3, we have shown that both physiological and oncological activation of FLT3 lead to the NF-kB pathway activation. Surprisingly, we have discovered during this study that the IKK2 inhibitor AS602868 directly interferes with the FLT3 kinase activity. This discovery encourages the therapeutic testing of AS602868, as it is targeting two kinases that play major roles for the pathogenesis of AML. To evaluate the therapeutic potential of AS602868, we have compared its effect on different steps of both the hematopoietic and leukemic process, in different types of experiments. In vitre and in vivo experiments have all demonstrated the existence of a pharmacological targeting of the stem-progenitor leukemic population by AS602868. The identical treatment in the control conditions had no or very few side effects on the normal haematopoiesis. We show for the first time the preferential targeting of the LSCs in vivo with an IKK2 inhibitor. Our results show that both normal and oncogenic activation of FLT3 can lead to the abnormal constitutive activation of the NF-kB pathway, present in AML. Our study identifies a new target of the IKK2 inhibitor AS602868 and reinforces the perspects of its use in the clinic. Finally, this work suggests that the pharmacological targeting of the leukemic stem cells in vivo has to be the main objective of the new therapies of AML.NICE-BU Sciences (060882101) / SudocSudocFranceF

Tunneling Nanotubes (TNTs): Intratumoral Cell-to-Cell Communication and Mitochondria Trafficking Through Connections by Tunneling Nanotubes—Effects on Cell Metabolism and Response to Therapy

International audience

Intercellular mitochondria trafficking highlighting the dual role of mesenchymal stem cells as both sensors and rescuers of tissue injury

International audienceMitochondria are crucial organelles that not only regulate the energy metabolism, but also the survival and fate of eukaryotic cells. Mitochondria were recently discovered to be able to translocate from one cell to the other. This phenomenon was observed in vitro and in vivo, both in physiological and pathophysiological conditions including tissue injury and cancer. Mitochondria trafficking was found to exert prominent biological functions. In particular, several studies pointed out that this process governs some of the therapeutic effects of mesenchymal stem cells (MSCs). In this review, we give an overview of the current knowledge on MSC-dependent intercellular mitochondria trafficking and further discuss the recent findings on the intercellular mitochondria transfer between differentiated and mesenchymal stem cells, their biological significance and the mechanisms underlying this process

The Typology of the Literary Character in E. Adamson’s Prose

Bakalaura darba „Tēlu tipoloģija E.Ādamsona prozā” pamatā ir Erika Ādamsona īsprozas un romāna „Sava ceļa gājējs” tēlu tipoloģijas analīze. Pētītas tēlu raksturīgākās īpatnības, tai skaitā arī kompleksi. Analizētas tās varoņu īpašības, kas nonākot saskarsmē ar dažādiem apstākļiem, maina cilvēka dzīves principus un pat turpmāko likteni, tēlu psiholoģija, personību raksturu veidošanās pamatprincipi. Aplūkoti jautājumi, kuriem bijusi tieša ietekme uz rakstnieka radošo procesu, atsevišķās nodaļās un apakšnodaļās analizēti cilvēku tipi E.Ādamsona novelēs, gadījuma un iedomu akcents cilvēka psihes tēlojumā, kā arī pētīti cilvēku tipi E.Ādamsona romānā „Sava ceļa gājējs”. Vērtēta E.Ādamsona oriģinalitāte prozā un prozas žanriskās piederības problēma. Atslēgas vārdi: Eriks Ādamsons, proza, tēlu tipoloģija, cilvēka psiholoģija, kompleksi.The Bachelor Paper “Typology of Personages in the Prose of E. Ādamsons” is based on the typology analysis of personages of the short prose and the novel “Sava ceļa gājējs” of Eriks Ādamsons. There are studied the most characteristic peculiarities of personages, including their complexes. There are analysed those qualities of the personages, which in different circumstances change the principles of life of a persons and even his/her further fate, psychology of personages, main principles of formation of character of personalities. There are discussed the issues which have had a great impact on the creative process of the author, in separate chapters and subchapters there are analysed the types of persons in the novels of E. Ādamsos, the accent of a chance and illusions in depiction of human psyche, as well as investigated the types of persons in the novel of E. Ādamsons „Sava ceļa gājējs”. There is assessed the originality of E. Ādamsons in prose and the problem of genre belonging of the prose. Key words: Eriks Ādamsons, prose, typology of personages, human psychology, complexes

β-Catenin mediates the establishment and drug resistance of MLL leukemic stem cells

SummaryIdentification of molecular pathways essential for cancer stem cells is critical for understanding the underlying biology and designing effective cancer therapeutics. Here, we demonstrated that β-catenin was activated during development of MLL leukemic stem cells (LSCs). Suppression of β-catenin reversed LSCs to a pre-LSC-like stage and significantly reduced the growth of human MLL leukemic cells. Conditional deletion of β-catenin completely abolished the oncogenic potential of MLL-transformed cells. In addition, established MLL LSCs that have acquired resistance against GSK3 inhibitors could be resensitized by suppression of β-catenin expression. These results unveil previously unrecognized multifaceted functions of β-catenin in the establishment and drug-resistant properties of MLL stem cells, highlighting it as a potential therapeutic target for an important subset of AMLs

Oxidative Phosphorylation Fueled by Fatty Acid Oxidation Sensitizes Leukemic Stem Cells to Cold

Dependency on mitochondrial oxidative phosphorylation (OxPhos) is a potential weakness for leukemic stem cells (LSC) that can be exploited for therapeutic purposes. Fatty acid oxidation (FAO) is a crucial OxPhos-fueling catabolic pathway for some acute myeloid leukemia (AML) cells, particularly chemotherapy-resistant AML cells. Here, we identified cold sensitivity at 4◦C (cold killing challenge; CKC4), commonly used for sample storage, as a novel vulnerability that selectively kills AML LSCs with active FAO-supported OxPhos while sparing normal hematopoietic stem cells. Cell death of OxPhos-positive leukemic cells was induced by membrane permeabilization at 4◦C; by sharp contrast, leukemic cells relying on glycolysis were resistant. Forcing glycolytic cells to activate OxPhos metabolism sensitized them to CKC4. Lipidomic and proteomic analyses showed that OxPhos shapes the composition of the plasma membrane and introduces variation of 22 lipid subfamilies between cold-sensitive and cold-resistant cells. Together, these findings indicate that steady-state energy metabolism at body temperature predetermines the sensitivity of AML LSCs to cold temperature, suggesting that cold sensitivity could be a potential OxPhos biomarker. These results could have important implications for designing experiments for AML research to avoid cell storage at 4◦C.</p