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 protective role of the microenvironment in hairy cell leukemia treatment: Facts and perspectives

Hairy cell leukemia (HCL) is an incurable, rare lymphoproliferative hematological malignancy of mature B cAlthough first line therapy with purine analogues leads to positive results, almost half of HCL patients relapse after 5-10 years, and standard treatment may not be an option due to intolerance or refractoriness. Proliferation and survival of HCL cells is regulated by surrounding accessory cells and soluble signals present in the tumor microenvironment, which actively contributes to disease progression. In vitro studies show that different therapeutic approaches tested in HCL impact the tumor microenvironment, and that this milieu offers a protection affecting treatment efficacy. Herein we explore the effects of the tumor microenvironment to different approved and experimental therapeutic options for HCL. Dissecting the complex interactions between leukemia cells and their milieu will be essential to develop new targeted therapies for HCL patients.Fil: Gargiulo, Ernesto. Luxembourg Institute Of Health; Luxemburgo. Chronic Lymphocytic Leukemia Laboratory; Dinamarca. PERSIMUNE; DinamarcaFil: Giordano, Mirta Nilda. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Niemann, Carsten U.. Chronic Lymphocytic Leukemia Laboratory; Dinamarca. Universidad de Copenhagen; DinamarcaFil: Moussay, Etienne. Luxembourg Institute Of Health; LuxemburgoFil: Paggetti, Jérôme. Luxembourg Institute Of Health; LuxemburgoFil: Morande, Pablo Elías. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; Argentina. Luxembourg Institute Of Health; Luxemburg

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

Targeting autophagy inhibits melanoma growth by enhancing NK cells infiltration in a CCL5-dependent manner

International audienceWhile blocking tumor growth by targeting autophagy is well established, its role on the infiltration of natural killer (NK) cells into tumors remains unknown. Here, we investigate the impact of targeting autophagy gene Beclin1 (BECN1) on the infiltration of NK cells into melanomas. We show that, in addition to inhibiting tumor growth, targeting BECN1 increased the infiltration of functional NK cells into melanoma tumors. We provide evidence that driving NK cells to the tumor bed relied on the ability of autophagy-defective tumors to transcriptionally overexpress the chemokine gene CCL5 Such infiltration and tumor regression were abrogated by silencing CCL5 in BECN1-defective tumors. Mechanistically, we show that the up-regulated expression of CCL5 occurred through the activation of its transcription factor c-Jun by a mechanism involving the impairment of phosphatase PP2A catalytic activity and the subsequent activation of JNK. Similar to BECN1, targeting other autophagy genes, such as ATG5, p62/SQSTM1, or inhibiting autophagy pharmacologically by chloroquine, also induced the expression of CCL5 in melanoma cells. Clinically, a positive correlation between CCL5 and NK cell marker NKp46 expression was found in melanoma patients, and a high expression level of CCL5 was correlated with a significant improvement of melanoma patients' survival. We believe that this study highlights the impact of targeting autophagy on the tumor infiltration by NK cells and its benefit as a novel therapeutic approach to improve NK-based immunotherapy

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