Diagnostic and Therapeutic Potential of Extracellular Vesicles in B-Cell Malignancies

Extracellular vesicles (EV), comprising microvesicles and exosomes, are particles released by every cell of an organism, found in all biological fluids, and commonly involved in cell-to-cell communication through the transfer of cargo materials such as miRNA, proteins, and immune-related ligands (e.g., FasL and PD-L1). An important characteristic of EV is that their composition, abundance, and roles are tightly related to the parental cells. This translates into a higher release of characteristic pro-tumor EV by cancer cells that leads to harming signals toward healthy microenvironment cells. In line with this, the key role of tumor-derived EV in cancer progression was demonstrated in multiple studies and is considered a hot topic in the field of oncology. Given their characteristics, tumor-derived EV carry important information concerning the state of tumor cells. This can be used to follow the outset, development, and progression of the neoplasia and to evaluate the design of appropriate therapeutic strategies. In keeping with this, the present brief review will focus on B-cell malignancies and how EV can be used as potential biomarkers to follow disease progression and stage. Furthermore, we will explore several proposed strategies aimed at using biologically engineered EV for treatment (e.g., drug delivery mechanisms) as well as for impairing the biogenesis, release, and internalization of cancer-derived EV, with the final objective to disrupt tumor–microenvironment communication.Fil: Gargiulo, Ernesto. Luxembourg Institute of Health; LuxemburgoFil: Morande, Pablo Elías. Luxembourg Institute of Health; Luxemburgo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Largeot, Anne. Luxembourg Institute of Health; LuxemburgoFil: Moussay, Etienne. Luxembourg Institute of Health; LuxemburgoFil: Paggetti, Jérôme. Luxembourg Institute of Health; Luxemburg

Etude du rôle de l'histone acétyltransférase MOZ dans l'hématopoïèse et la leucémogenèse

Ma thèse a porté sur l'étude du rôle de l'histone acétyltransférase MOZ (monocytic leukaemia zinc finger protein) dans l'hématopoïèse et la leucémogenèse. Le gène MOZ est impliqué dans plusieurs translocations chromosomiques retrouvées dans des leucémies aiguës myéloïdes (LAM). Nous avons étudié l interaction potentielle entre MOZ et MLL (mixed lineage leukemia), une histone méthyltransférase dont le gène est très fréquemment réarrangé dans les leucémies aiguës humaines. Nous avons montré que MOZ et MLL interagissent au sein d un même complexe protéique et coopèrent afin d activer la transcription de certains gènes HOX dans une population cellulaire humaine (CD34+) très enrichie en cellules souches hématopoïétiques (CSH). Les gènes HOX codent des facteurs de transcription indispensables à l embryogenèse et à l hématopoïèse (en particulier pour l auto-renouvellement des CSH), et impliqués dans la leucémogenèse. Afin d étudier précisément le rôle de MOZ dans l hématopoïèse murine, nous avons généré des souris déficientes pour Moz uniquement dans les cellules hématopoïétiques. Ces souris sont viables mais présentent des anomalies de l hématopoïèse en particulier au niveau des progéniteurs hématopoïétiques et des CSH. MOZ est donc impliquée dans la régulation de l hématopoïèse murine post-natale. Concernant la leucémogenèse associée à MOZ, nous avons généré des poissons-zèbres transgéniques exprimant une protéine de fusion de MOZ humaine (MOZ-TIF2). Ces poissons développent une LAM démontrant ainsi le très grand pouvoir leucémogène de cette protéine chimérique. Ces poissons constituent le premier modèle de LAM chez le poisson-zèbre.My thesis concerns the study of the role of the histone acetyltransferase MOZ (monocytic leukaemia zinc finger protein) in haematopoiesis and leukaemogenesis. MOZ gene is implicated in several chromosomal translocations found in acute myeloid leukaemia (AML). We studied the potential interaction between MOZ and MLL (mixed lineage leukemia), a histone methyltransferase whose gene is frequently translocated in human acute leukaemia. We showed that MOZ and MLL interact within a same complex and cooperate to activate transcription of HOX genes in a human cell population (CD34+) very enriched in haematopoietic stem cells (HSCs). HOX genes encode transcription factors essential for embryogenesis and haematopoiesis (particularly in HSCs self-renewal), and are involved in leukaemogenesis. To study precisely the role of MOZ in murine haematopoiesis, we generated deficient mice for Moz only in haematopoietic cells. These mice are viable but display abnormalities in haematopoiesis, in particular regarding haematopoietic progenitors and HSCs. Hence, MOZ is implicated in the regulation of adult murine haematopoiesis. Regarding leukaemogenesis associated with MOZ, we generated transgenic zebrafishes expressing a human MOZ fusion protein (MOZ-TIF2). Some fishes develop an AML, thus demonstrating the important leukaemogenic power of this chimeric protein. These fishes represent the first model of AML in zebrafish.DIJON-BU Sciences Economie (212312102) / SudocSudocFranceF

The prohibitin-binding compound fluorizoline induces apoptosis in chronic lymphocytic leukemia cells ex vivo but fails to prevent leukemia development in a murine model

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Hypoxic tumor-derived microvesicles negatively regulate NK cell function by a mechanism involving TGF-β and miR23a transfer

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Symplekin, a polyadenylation factor, prevents MOZ and MLL activity on HOXA9 in hematopoietic cells

International audienceMOZ and MLL encoding a histone acetyltransferase and a histone methyltransferase, respectively, are targets for recurrent chromosomal translocations found in acute myeloblastic or lymphoblastic leukemia. We have previously shown that MOZ and MLL cooperate to activate HOXA9 gene expression in hematopoietic stem/progenitors cells. To dissect the mechanism of action of this complex, we decided to identify new proteins interacting with MOZ. We found that the scaffold protein Symplekin that supports the assembly of polyadenylation machinery was identified by mass spectrometry. Symplekin interacts and co-localizes with both MOZ and MLL in immature hematopoietic cells. Its inhibition leads to a decrease of the HOXA9 protein level but not of Hoxa9 mRNA and to an over-recruitment of MOZ and MLL onto the HOXA9 promoter. Altogether, our results highlight the role of Symplekin in transcription repression involving a regulatory network between MOZ, MLL and Symplekin

Transcription intermediary factor 1γ is a tumor suppressor in mouse and human chronic myelomonocytic leukemia

Transcription intermediary factor 1γ (TIF1γ) was suggested to play a role in erythropoiesis. However, how TIF1γ regulates the development of different blood cell lineages and whether TIF1γ is involved in human hematological malignancies remain to be determined. Here we have shown that TIF1γ was a tumor suppressor in mouse and human chronic myelomonocytic leukemia (CMML). Loss of Tif1g in mouse HSCs favored the expansion of the granulo-monocytic progenitor compartment. Furthermore, Tif1g deletion induced the age-dependent appearance of a cell-autonomous myeloproliferative disorder in mice that recapitulated essential characteristics of human CMML. TIF1γ was almost undetectable in leukemic cells of 35% of CMML patients. This downregulation was related to the hypermethylation of CpG sequences and specific histone modifications in the gene promoter. A demethylating agent restored the normal epigenetic status of the TIF1G promoter in human cells, which correlated with a reestablishment of TIF1γ expression. Together, these results demonstrate that TIF1G is an epigenetically regulated tumor suppressor gene in hematopoietic cells and suggest that changes in TIF1γ expression may be a biomarker of response to demethylating agents in CMML

Formate overflow drives toxic folate trapping in MTHFD1 inhibited cancer cells

Cancer cells fuel their increased need for nucleotide supply by upregulating one-carbon (1C) metabolism, including the enzymes methylenetetrahydrofolate dehydrogenase–cyclohydrolase 1 and 2 (MTHFD1 and MTHFD2). TH9619 is a potent inhibitor of dehydrogenase and cyclohydrolase activities in both MTHFD1 and MTHFD2, and selectively kills cancer cells. Here, we reveal that, in cells, TH9619 targets nuclear MTHFD2 but does not inhibit mitochondrial MTHFD2. Hence, overflow of formate from mitochondria continues in the presence of TH9619. TH9619 inhibits the activity of MTHFD1 occurring downstream of mitochondrial formate release, leading to the accumulation of 10-formyl-tetrahydrofolate, which we term a ‘folate trap’. This results in thymidylate depletion and death of MTHFD2-expressing cancer cells. This previously uncharacterized folate trapping mechanism is exacerbated by physiological hypoxanthine levels that block the de novo purine synthesis pathway, and additionally prevent 10-formyl-tetrahydrofolate consumption for purine synthesis. The folate trapping mechanism described here for TH9619 differs from other MTHFD1/2 inhibitors and antifolates. Thus, our findings uncover an approach to attack cancer and reveal a regulatory mechanism in 1C metabolism