No description available.

Le Lymphome à Cellules du Manteau (LCM) est une entité récemment identifiée qui se caractérise par la translocation génétique t(11 ;14)(q13 ;q32) et compte pour 2 à 10 % de tous les Lymphomes non-Hodgkiniens. Avec une survie médiane entre 3 et 5 ans après le diagnostic, le LCM est une pathologie agressive et malgré les récentes avancées thérapeutiques, peu d’informations sont disponibles concernant ses facteurs pronostiques. Certaines études ont analysé le rôle des caractéristiques clinicopathologiques et des nouvelles stratégies thérapeutiques, mais on connait peut le rôle des facteurs environnementaux et du mode de vie sur le pronostic des patients atteints de LCM. Entre 2008 et 2012, le groupe LYSA a mené en France deux essais cliniques prospectifs multicentriques : LM manteau 2010 SA "RiBVD" (NCI01457144) et Manteau 2007 SJ "LyMa" (NCT00921414). Après une comparaison de ces patients avec les patients de population générale, l’effet de facteurs socioéconomiques et des habitudes de vie sur la survie des patients a été étudié à l’aide d’un questionnaire qualitatif administré à tous les volontaires après le diagnostic. Nos résultats suggèrent qu’un faible niveau d’éducation, un indice de masse corporelle élevé et de la consommation d’alcool sont associés à un risque de décès plus élevé chez les patients atteints de LCM. Toutefois, l’étude de tels facteurs et de leur influence sur un sous-type de LNH aussi rare requiert des échantillons d’étude de taille plus importante. L’élargissement des critères d’inclusion des patients dans les essais cliniques permettrait de sélectionner davantage de patients mais aussi des patients mieux représentatifs de la population générale. Enfin, l’intégration systématique de ce type de questionnaire dans les protocoles d’essais cliniques serait aussi un atout majeur. / Mantle Cell Lymphoma (MCL) is a recently defined entity, typically characterised by the genetic translocation t(11 ;14)(q13 ;q32) and counting for 2 - 10% of all non-Hodgkin Lymphomas. With a median survival between 3 and 5 years after diagnosis, MCL is an agressive disease and despite the recent therapeutic advances little in know about its prognostic factors. Some studies had investigated clinicopathological features and new treatment strategies, but there is a lack of knowledge regarding the impact of lifestyle and environnemental factors on outcome of MCL patients. From 2008 to 2012, the LYSA Group conducted in France two prospective multi center clinical trials on MCL : LM manteau 2010 SA "RiBVD" (NCI01457144) and Manteau 2007 SJ "LyMa" (NCT00921414). After a comparison of these patients with population-based data, socioeconomic factors, lifestyle factors and their influence on survival had been investigated through a qualitative survey administrated to each volunteer after diagnosis. Our findings suggest that low educational attainment, low body body mass index and alcohol consumption are associated with a higher risk of death in MCL. However, to investigate lifestyle factors in this rare NHL subtype, larger studies should be carried out. Clinical trial inclusion criteria must be widen to select more patients and patients more representative of general population. Implementation of these epidemiological studies in clinical practice should be considered.

Les lymphomes B non-Hodgkiniens (LNHB) représentent le type d’hémopathie maligne le plus fréquent. Ces pathologies sont traitées par l’association de chimiothérapies conventionnelles et d’immunothérapies dirigées contre le CD20. Bien qu’efficace, 40% des patients résistent ou rechutent après le traitement. Deux raisons peuvent expliquer ces échecs thérapeutiques : 1) l’absence de cibles thérapeutiques impliquées dans plusieurs processus oncogéniques et 2) l’absence de modèles pré-cliniques de LNHB pertinents pour le test de molécules thérapeutiques et la compréhension de la lymphomagenèse. Le calcium est un messager ubiquitaire qui est impliqué dans de nombreux processus cellulaires en condition physiologique et pathologique. La principale voie d’entrée de calcium dans les lymphocytes B est l’entrée capacitive de calcium médiée par Orai1 et STIM1. Ces deux protéines ont été largement décrites pour être impliquées dans les processus tumoraux de nombreux cancers, cependant leurs rôles dans la lymphomagenèse restait à élucider. Nos travaux ont révélé l'implication de la signalisation calcique dans la mort induite par le GA101, un anti CD20 de nouvelle génération actuellement en essai clinique. De plus, nous avons mis en évidence l’implication des protéines Orai1 et STIM1 dans la migration des cellules cancéreuses de LNHB. De manière intéressante, l’implication de ces deux protéines dans la migration cellulaire est calcium indépendante, suggérant donc un nouveau rôle de ces protéines. Enfin, grâce à la technologie des capsules cellulaires nous avons établi un nouveau modèle 3D de lymphome mimant la niche tumorale en incluant des cellules du microenvironnement et de la matrice extracellulaire. Ce modèle semble particulièrement pertinent pour le screening de molécules et la compréhension des mécanismes de la lymphomagenèse. Ce travail de thèse révèle ainsi le ciblage de Orai1 et STIM1 comme potentiellement intéressant dans le traitement du LNHB. / B-cell non-Hodgkin lymphomas (BNHL) are the most common hematological malignancies, usually treated with a combination of chemotherapy and anti CD20 immunothérapie. However, 40% of patients are resistant or relapse after treatment. These therapeutic failures could be due to 1) lack of therapeutic targets implicated in several oncogenic processes, 2) lack of relevant preclinical BNHL models for drug screening and lymphomagenesis studies. Calcium is an essential second messenger involved in various cell functions. In B cells, calcium entry is mainly due to Orai1 and STIM1 proteins, both of which have been associated with oncogenesis on solid tumors. However, their role in lymphomagenesis still remains to be elucidated. Our work shows that calcium signaling in BNHL cells participates in cell death induced by GA101, a novel anti-CD20 monoclonal antibody. We also demonstrate that Orai1 and STIM1 play a role in BNHL cell migration. Interestingly, both proteins controlled cell migration in a calcium-independent manner, suggesting a new role for these proteins. Finally, using cellular capsule technology, we established a new BNHL 3D model mimicking tumoral niche by including extracellular matrix and stromal cells. This new model could be used for drug screening and understanding lymphomagenesis. In summary, this work suggests that targeting of Orai1 and STIM1 is promising for BNHL treatment.

Wachstumsfaktor bedingte Aktivierung des PI3K/Akt/mTOR Signalweg wirkt positiv auf Vermehrung und Überleben. Konstitutive Aktivierung des Signalweges in NHL ist jedoch an Tumorprogression und Therapieresistenz beteiligt. Am Zelllinienmodell wurden zwei mögliche Therapiestrategien der PI3K/Akt/mTOR Inhibition erprobt, PI3K Inhibition mit BKM120 und horizontale Kombination von Zytostatika mit PI3K/Akt/mTOR Inhibitoren Erstens, BKM120 hat Antitumoraktivität in NHL und induziert Zelltod. Auf molekularer Ebene führt BKM120 vermittelte Dephosphorylierung von CDK1 an Y15 zur Aktivierung des M-Phase Komplex CDK1/Zyklin B und Eintritt in die Mitose. Parallel erlaubt die Degradation von Zyklin A und Hochregulation von Zyklin B Progression bis zur Metaphase, hemmt jedoch die Transition in die Anaphase. Anhaltender Metaphasearrest bewirkt programmierten Zelltod über den intrinsischen Signalweg der Apoptose durch Hochregulation der BH3-onlys Puma und Hrk, Aktivierung von Bax/Bak und proteolytische Spaltung von Caspase 9. Verlust von Bax/Bak oder Caspase Inhibition schützt vor BKM120 vermitteltem Zelltod. Bax/Bak defiziente Zellen, welche zusätzlich p53 Mutationen aufweisen, werden polyploid. Die Polyploidie ist ATM-MEK1/2 abhängig und kann mit Caffeine oder U0126blockiert werden. Zur Vermeidung von Polyploidie bedingter Tumorprogression, sollte BKM120 nur in Verbindung mit MAPK/ATM Inhibitoren verwendet werden. Zweitens. Horizontale Kombination PI3K/Akt/mTOR Inhibitoren mit cytotoxischen Substanzen schützt vor Apoptose. Der Schutzeffekt tritt auschließlich bei niedrigen Konzentration auf und ist unabhängig von der Art des Inhibitors bzw. Ebene der Inhibition. Das Onkogen und NFkB Target Pim-2 ist möglicherweise am Schutzmechanismus beteiligt. Durch die PI3K/Akt/mTOR vermittelte Pim-2 Regulation ergibt sich eine neue Rückkopplungsschleife. Im Fazit erschwert die Komplexizität des PI3K/Akt/mTOR Signalweges die Etablierung von Therapien. / Growth factor mediated activation of the PI3K/Akt/mTOR pathway positively regulates proliferation and survival. Constitutive activation in NHL, however, is correlated with tumor progression and therapeutic resistance. Therefore, two possible strategies were tested in a cell line model system, Inhibition of PI3K with BKM120 and PI3K/Akt/mTOR Inhibition in addition to cytostatic drug administration. First, it is demonstrated that the pan PI3K inhibitor BKM120 has antitumor activity in NHL and induces cell death. On molecular level, BKM120 mediated dephosphorylation of CDK1 on Y15 causes activation of the M-phase complex CDK1/Cyclin B and entry into mitosis. In parallel, degradation of Cyclin A and Upregulation of Cyclin B enables progression into metaphase but inhibits transition into anaphase. Prolonged metaphase arrest induces programmed cell death via the intrinsic apoptosis pathway by upregulation of the BH3-onlys Puma and Hrk, activation of Bax/Bak and proteolytic cleavage of caspase-9. Loss of Bax/Bak or caspase inhibition protects from BKM120 induced apoptosis. Bax/Bak deficient cells with additional p53 mutation become polyploid. This polyploidy is ATM-MEK1/2 dependent and can be blocked with Caffeine or U0126. To prevent polyploidy related tumor progression, BKM120 should administered only in combination with ATM or MEK inhibitors. Second, combination of PI3K/Akt/mTOR inhibitors with cytotoxic agents protects from apoptosis. The protective effect is only detectable with low PI3K/Akt/mTOR inhibitor concentrations and independent of inhibitor type or cascade level. The oncogene and NFkB target is possibly involved in apoptosis protection and inhibition of NFkB neutralizes the protective effect. PI3K/Akt/mTOR mediated Pim-2 regulation reveals a new feedback loop within the pathway. In conclusion, the complexity of the PI3K/Akt/mTOR pathway impedes therapeutic targeting.

Die aberrante Aktivierung des NOTCH Signalweges trägt entscheidend zu verschiedensten malignen Erkrankungen im Menschen bei. Basierend auf der Analyse von hochdimensionalen Microarray-Datensätzen von klassischen Hodgkin Lymphoma Fällen und nicht-Hodgkin Fällen, haben wir eine Hodgkin Lymphoma-spezifische NOTCH Signatur identifiziert. Diese wird von dem essentiellen NOTCH-Koaktivator Mastermindlike 2 (MAML2) signifikant dominiert. Auf der Grundlage dieses Resultates haben wir die Rolle von MAML2 im Kontext des Hodgkin Lymphoma-spezifischen, aberrant regulierten NOTCH Signalweges weiter untersucht. Die signifikante Überexpression von MAML2 im Hodgkin Lymphom konnte in verschiedenen Hodgkin Lymphom Zelllinien und auch durch die immunhistochemische Analyse von primären Hodgkin Lymphom Fällen verifiziert werden. Mit Hilfe des Knockdowns von MAML2 bzw. der Inhibition des NOTCH Signalweges durch die Verwendung einer kompetitiv, dominant-negativ wirkenden, trunkierten Variante von MAML1 konnte daraufhin gezeigt werden, dass die Überexpression von MAML2 der limitierende Faktor für die Hodgkin Lymphomaspezifische, pathologische Deregulation des NOTCH Signalweges ist. Die MAML2- vermittelte Überaktivierung des NOTCH Signalweges ist darüber hinaus essentiell für die Proliferation von Hodgkin Lymphom Zelllinien und die aberrante Expression der NOTCH Zielgene HES7 und HEY1. Das konstitutive Vorhandensein von aktiviertem, intrazellulären NOTCH1 in Hodgkin Lymphom Zelllinien impliziert darüber hinaus,dass der Signalweg im Hodgkin Lymphom zellautonom aktiviert ist. In dieser Arbeit wird damit ein neuer, pathologisch hochwirksamer Mechanismus der NOTCH Signalweg-Deregulation aufgedeckt. / Inappropriate activation of the NOTCH signaling pathway, e.g. by activating mutations, contributes to the pathogenesis of various human malignancies. Using a bottom up approach based on the acquisition of high–dimensional microarray data of classical Hodgkin lymphoma (cHL) and non-Hodgkin B cell lymphomas as control, we identify a cHL specific NOTCH gene-expression signature dominated by the NOTCH co-activator Mastermind-like 2 (MAML2). This set the basis for demonstrating that aberrant expression of the essential NOTCH co-activator MAML2 provides an alternative mechanism to activate NOTCH signaling in human lymphoma cells. Using immunohistochemistry we detected high-level MAML2 expression in several B cell-derived lymphoma types, including cHL cells, whereas in normal B cells no staining for MAML2 was detectable. Inhibition of MAML protein activity by a dominant negative form of MAML or by shRNAs targeting MAML2 in cHL cells resulted in down-regulation of the NOTCH target genes HES7 and HEY1, which we identified as overexpressed in cHL cells, and in reduced proliferation. In order to target the NOTCH transcriptional complex directly we developed short peptide constructs that competitively inhibit NOTCH dependent transcriptional activity as demonstrated by NOTCH reporter assays and EMSA analyses. We conclude that NOTCH signaling is aberrantly activated in a cell autonomous manner in cHL. This is mediated by high-level expression of the essential NOTCH coactivator MAML2, a protein that is only weakly expressed in B cells from healthy donors. Using short peptide constructs we moreover show, that this approach is promising in regard to the development of NOTCH pathway inhibitors that will also work in NOTCH associated malignancies that are resistant to -secretase inhibition.

INTRODUÇÃO. Os genes da família paraoxonase (PON1, PON2 e PON3) apresentam grande homologia estrutural. PON1 está associada à molécula de HDL e possui funções fisiológicas, sendo a principal a de lactonase. PON1 também pode proteger as moléculas de LDL de modificações oxidativas. Embora o papel biológico mais conhecido das paraoxonases seja a prevenção da aterosclerose, elas também atuam sobre o estresse oxidativo envolvido na patogênese de outras condições como doenças inflamatórias, infecções e neoplasias. Toda a família PON parece estar implicada no desenvolvimento de linfomas. O polimorfismo L55M de PON1 foi relacionado a um maior risco para linfomas em indivíduos da população geral, enquanto PON3 e PON2 foram relacionadas à sobrevida de células tumorais. A Imunodeficiencia comum variável (ICV) é uma doença heterogênea caracterizada pela redução dos niveis de IgG, IgA e/ou IgM e da função de anticorpo. As manifestações clínicas incluem a presença de infecções recorrentes ou crônicas, doenças inflamatórias/autoimunes e incidência aumentada de malignidades como linfomas não-Hodgkin (LNH) e câncer gástrico. OBJETIVO: estudar os polimorfismos de PON1 e PON2 bem como a atividade arilesterase de PON1 e sua relação com o perfil lipídico, morbidade, mortalidade e presença de fatores de risco para linfoma LNH em pacientes com ICV. MÉTODOS/RESULTADOS: Foram avaliadas as frequências alélicas dos polimorfismos de PON1 e PON2, o perfil lipídico e a atividade arilesterase da PON1 em 63 pacientes com ICV e 130 controles saudáveis. No grupo de pacientes foi analisada a presença de fatores de risco para LNH e parâmetros de morbidade e gravidade da doença. O polimorfismo Q192R da PON1 e os polimorfismos de PON2 (S311C e A148G) não diferiram entre os grupos e não apresentaram relação com os parâmetros analisados. O genótipo 55MM e o alelo 55M foram mais frequentes no grupo ICV em relação ao grupo controle. A atividade arilesterase foi similar em pacientes e controles apresentando correlação positiva com os níveis de HDL. Pacientes com o genótipo 55MM apresentaram menor atividade de PON1 associada a maior morbidade da doença representada pela maior frequência de infecções de vias aéreas e maior taxa de internações. O genótipo 55MM também apresentou relação com a presença de fatores de risco para LNH como hiperplasia nodular linfoide (HNL) e linfonodomegalias. Por outro lado, a análise dos alelos demonstrou que a menor morbidade da doença foi associada à presença do alelo 55L, que apresentou relação com menor frequência de HNL e linfonodomegalia e menor ocorrência de óbitos. O alelo 55M apresentou relação com história familiar de imunodeficiências e neoplasias hematológicas. CONCLUSÃO: Este constitui o primeiro relato demonstrando maior frequência do genótipo 55MM e do alelo 55M em pacientes com ICV. Nossos resultados são sugestivos de que a presença do alelo 55L possa estar associado a um melhor prognóstico da doença. Inversamente, sugerem que pacientes com o genótipo 55MM apresentem maior morbidade e, possivelmente, maior risco para LNH / INTRO: The paraoxonase gene family (PON1, PON2 and PON3) has great structural homology. PON1 is associated with the HDL molecule and possess many physiological roles, the major one being of a lactonase. PON1 also protects LDL molecules against oxidative modifications. Although the best known biological role of PONs is the prevention of atherosclerosis, they also act on the oxidative stress involved in the pathogenesis of different conditions such as inflammatory diseases, infections and malignancies. The whole PON family appears to be implicated in the development of lymphomas. The L55M polymorphism of PON1 was related with a higher risk for lymphoma in the general population while PON3 and PON2 were related to survival of tumor cells. The Common Variable Immunodeficiency (ICV) is a heterogeneous disease characterized by reduced levels of IgG, IgA and/or IgM and antibody function. Clinical manifestations include the presence of chronic or recurrent infections, inflammatory/autoimmune diseases and increased incidence of malignancies such as non-Hodgkin lymphoma (NHL) and gastric cancer. OBJECTIVE: to study the PON1 and PON2 polymorphisms and the arylesterase activity of PON1 and its correlation with the lipid profile, morbidity, mortality and the presence of risk factors for NHL in CVID patients. METHODS/RESULTS: We evaluated the allele frequencies of polymorphisms of PON1 and PON2, lipid profile and arylesterase activity of PON1 in 63 patients with CVID and 130 healthy controls. In the group of patients we analyzed the presence of risk factors for NHL and parameters of morbidity and disease severity. The Q192R polymorphism of the PON1 and PON2 polymorphisms (A148G and S311C) did not differ between groups and did not correlate with the parameters analyzed. The 55MM genotype and the 55M allele were more frequent in the CVID group than in control group. The arylesterase activity was similar in patients and controls showing a positive correlation with HDL levels. Patients with genotype 55MM had lower PON1 activity, associated with increased morbidity of the disease represented by the higher frequency of respiratory infections and a higher rate of hospitalization. The 55MM genotype also was correlated with the presence of risk factors for NHL, such as lymphoid nodular hyperplasia (HNL) and lymphadenopathy. Moreover, analysis of the alleles showed that less morbidity of the disease was associated with the presence of the allele 55L, which was correlated with a lower frequency of HNL and lymphadenopathies and fewer deaths. The 55M allele was correlated with a family history of immunodeficiency and hematological malignancies. CONCLUSION: This is the first report showing a greater frequency of 55MM genotype and 55M allele in patients with CVID. Our results suggest that the presence of 55L allele may be associated with a better prognosis. Conversely, these results suggest that patients with the 55MM genotype show higher morbidity and, possibly, higher risk for NHL

Le syndrome de Williams-Beuren (SWB} est une maladie génétique rare causée par une microdélétion de la région 7q11.23. A la suite de l'observation clinique d'une jeune fille atteinte du SWB ayant développé un lymphome de Burkitt à l'âge de 7 ans, nous nous sommes intéressé au lien génétique entre SWB et cancer. L'étude d'une série de cas de cancers survenus chez des enfants atteints de SWB a montré que les lymphomes non-hodgkiniens de type B étaient surreprésentés dans cette population puisque 73% des cancers chez les enfants atteints du SWB étaient des LNH-B. La région critique du SWB a été explorée par CGH-array et séquencage haut-débit dans les échantillons sains et tumoraux de 2 patients atteints de SWB. Aucune perte d'hétérozygotie de la région 7q11.23 n'a été trouvé. En outre, une délétion somatique de la région 7q11.23 a été identifiée dans un lymphome de Burkitt sporadique (Guenat D et al., J Hematol Oncol, 2014). Nous avons ensuite exploré les mécanismes de réponses aux dommages à l'ADN dans des lignées de fibroblastes primaires dérivées de patients atteints du SWB ainsi que dans des lignées 293T traitées avec des siRNA ciblant RFC2, BAZ1B et GTF2/, 3 gènes localisés en 7q11.23 et codant des protéines de réparation de l'ADN. Les cellules dérivées de patients SWB ont montré un défaut de signalisation dans les voies ATM/ATR-dépendantes en réponse aux dommages à l'ADN (Guenat D et al., DNA repair, article soumis). L'haploinsuffisance de la région 7q11.23 associée au SWB pourrait donc jouer un rôle dans la lymphomagenèse B par l'altération de voies de réponse aux dommages à l'ADN ATM/ATR-dépendantes. Cependant, ces résultats mériteraient d'être confirmés dans des modèles murins reproduisant le génotype complet du SWB. Enfin, des données épidémiologiques exhaustives sur l'incidence des pathologies tumorales chez les individus atteints du SWB sont indispensables pour affirmer qu'une prédisposition au cancer existe chez ces patients / Williams-Beuren syndrome (WBS) is a genetic disorder caused by a microdeletion at 7q11.23. The case of a young girl with WBS who developed a Burkitt lymphoma at the age of 7 leads us to explore the genetic link between WBS and cancer. The study of a series of cancers occurred in WBS patients during childhood have shown that B-cell non hodgkin lymphoma are over-represented in this population since 73% cancer cases in WBS were B-NHL. The critical region of WBS was explored by array-CGH and high-throughput sequencing in normal and tumor samples from WBS patients. No loss of heterozygosity at 7q11.23 was found. ln addition, a somatic deletion at 7q11.23 was observed in a sporadic case of Burkitt lymphoma (Guenat D et al., J Hematol Oncol, 2014). DNA damage response mechanisms were then explored in primary fibroblast cell lines derived from WBS patients as well as in 293T cell line treated with siRNA targeting RFC2, GTF2/ and BAZ1 B, 3 genes mapping at 7q11.23 that encode proteins involved in DNA damage response. WBS patients cell lines have shown a defect in ATM/ ATR-dependent DNA damage response pathways (Guenat D et al., DNA Repair, article submitted). Haploinsufficiency of the 7q11.23 region associated with WBS might play a role in B-cell lymphomagenesis through the alteration of ATM/ATR-dependent DNA damage response pathways. However, these results deserve to be confirmed in mouse models that reproduce the complete genotype of human WBS. Finally, strong epidemiological data would be required to confirm the predisposition to cancer in WBS patients.

Les lymphomes non hodgkiniens (LNH) regroupent un panel hétérogène de pathologies originaires de cellules lymphatiques. Parmi les LNH à cellules B matures, la leucémie lymphoïde chronique (LLC) constitue la forme de leucémie de l’adulte la plus fréquente en Occident. La physiopathologie des LNH à cellules B matures est marquée par l’inhibition des mécanismes de la mort cellulaire, notamment via la surexpression de la protéine MCL-1. Une première partie de ce travail de thèse a été de déterminer quelles pouvaient être les enzymes de déubiquitination (DUBs) impliquées dans la survie des LNH à cellules B matures et la stabilisation de MCL-1. Notre étude a permis d’identifier la DUB USP14, qui est liée au système ubiquitine-protéasome, comme capable de réguler MCL-1 et la survie cellulaire. Nos travaux montrent également pour la première fois que l’activité DUB des cellules, ainsi que l’activité d’USP14, sont directement régulées par la signalisation du BCR via l'activité de la tyrosine kinase SYK. Le FTY720, un analogue de la sphingosine utilisé comme immunosuppresseur dans la sclérose en plaques, a montré un effet cytotoxique dans des hémopathies malignes sans toutefois que son mécanisme d’action soit clairement expliqué. Une deuxième partie de ce travail de thèse a été de caractériser la mort induite par le FTY720. Notre étude montre que la caractérisation de la morphologie cellulaire et des marqueurs induits par la mort due au FTY720 dans les LLC correspond en fait à une nécrose cellulaire programmée indépendante de RIPK1, mais dépendante d'une enzyme régulatrice de la fission mitochondriale, DRP1. / Non-Hodgkin lymphoma (NHL) include a diverse range of pathologies originate from the lymphatic cells. Among the mature B-cell NHL, chronic lymphocytic leukemia (CLL) is the most common adult leukemia in the western countries. The pathophysiology of mature B-cell NHL is marked by the inhibition of cell death mechanisms, particularly through the overexpression of MCL-1 protein. The first part of this thesis was to determine which deubiquitinating enzymes (DUBs) are involved in the survival of mature B-cell NHL and in the stabilization of MCL-1. Our study identified the DUB USP14, which is linked to the ubiquitin-proteasome system, as able to regulate MCL-1 and cell survival. Our work also shows for the first time that the DUB activity of the cells and the activity of USP14 are directly regulated by BCR signaling through the activity of the SYK tyrosine kinase. FTY720, a sphingosine analog used as an immunosuppressive drug in multiple sclerosis, showed a cytotoxic effect in hematological malignancies but its mechanism of action is not well understood. A second part of this thesis was to characterize the death induced by FTY720. Our study shows that the characterization of the cellular morphology and markers induced by death due to FTY720 in the LLC corresponds in fact to a programmed RIPK1-independent necrosis cell death, but dependent on DRP1, a regulatory enzyme of the mitochondrial fission.

No description available.

INTRODUÇÃO. Os genes da família paraoxonase (PON1, PON2 e PON3) apresentam grande homologia estrutural. PON1 está associada à molécula de HDL e possui funções fisiológicas, sendo a principal a de lactonase. PON1 também pode proteger as moléculas de LDL de modificações oxidativas. Embora o papel biológico mais conhecido das paraoxonases seja a prevenção da aterosclerose, elas também atuam sobre o estresse oxidativo envolvido na patogênese de outras condições como doenças inflamatórias, infecções e neoplasias. Toda a família PON parece estar implicada no desenvolvimento de linfomas. O polimorfismo L55M de PON1 foi relacionado a um maior risco para linfomas em indivíduos da população geral, enquanto PON3 e PON2 foram relacionadas à sobrevida de células tumorais. A Imunodeficiencia comum variável (ICV) é uma doença heterogênea caracterizada pela redução dos niveis de IgG, IgA e/ou IgM e da função de anticorpo. As manifestações clínicas incluem a presença de infecções recorrentes ou crônicas, doenças inflamatórias/autoimunes e incidência aumentada de malignidades como linfomas não-Hodgkin (LNH) e câncer gástrico. OBJETIVO: estudar os polimorfismos de PON1 e PON2 bem como a atividade arilesterase de PON1 e sua relação com o perfil lipídico, morbidade, mortalidade e presença de fatores de risco para linfoma LNH em pacientes com ICV. MÉTODOS/RESULTADOS: Foram avaliadas as frequências alélicas dos polimorfismos de PON1 e PON2, o perfil lipídico e a atividade arilesterase da PON1 em 63 pacientes com ICV e 130 controles saudáveis. No grupo de pacientes foi analisada a presença de fatores de risco para LNH e parâmetros de morbidade e gravidade da doença. O polimorfismo Q192R da PON1 e os polimorfismos de PON2 (S311C e A148G) não diferiram entre os grupos e não apresentaram relação com os parâmetros analisados. O genótipo 55MM e o alelo 55M foram mais frequentes no grupo ICV em relação ao grupo controle. A atividade arilesterase foi similar em pacientes e controles apresentando correlação positiva com os níveis de HDL. Pacientes com o genótipo 55MM apresentaram menor atividade de PON1 associada a maior morbidade da doença representada pela maior frequência de infecções de vias aéreas e maior taxa de internações. O genótipo 55MM também apresentou relação com a presença de fatores de risco para LNH como hiperplasia nodular linfoide (HNL) e linfonodomegalias. Por outro lado, a análise dos alelos demonstrou que a menor morbidade da doença foi associada à presença do alelo 55L, que apresentou relação com menor frequência de HNL e linfonodomegalia e menor ocorrência de óbitos. O alelo 55M apresentou relação com história familiar de imunodeficiências e neoplasias hematológicas. CONCLUSÃO: Este constitui o primeiro relato demonstrando maior frequência do genótipo 55MM e do alelo 55M em pacientes com ICV. Nossos resultados são sugestivos de que a presença do alelo 55L possa estar associado a um melhor prognóstico da doença. Inversamente, sugerem que pacientes com o genótipo 55MM apresentem maior morbidade e, possivelmente, maior risco para LNH / INTRO: The paraoxonase gene family (PON1, PON2 and PON3) has great structural homology. PON1 is associated with the HDL molecule and possess many physiological roles, the major one being of a lactonase. PON1 also protects LDL molecules against oxidative modifications. Although the best known biological role of PONs is the prevention of atherosclerosis, they also act on the oxidative stress involved in the pathogenesis of different conditions such as inflammatory diseases, infections and malignancies. The whole PON family appears to be implicated in the development of lymphomas. The L55M polymorphism of PON1 was related with a higher risk for lymphoma in the general population while PON3 and PON2 were related to survival of tumor cells. The Common Variable Immunodeficiency (ICV) is a heterogeneous disease characterized by reduced levels of IgG, IgA and/or IgM and antibody function. Clinical manifestations include the presence of chronic or recurrent infections, inflammatory/autoimmune diseases and increased incidence of malignancies such as non-Hodgkin lymphoma (NHL) and gastric cancer. OBJECTIVE: to study the PON1 and PON2 polymorphisms and the arylesterase activity of PON1 and its correlation with the lipid profile, morbidity, mortality and the presence of risk factors for NHL in CVID patients. METHODS/RESULTS: We evaluated the allele frequencies of polymorphisms of PON1 and PON2, lipid profile and arylesterase activity of PON1 in 63 patients with CVID and 130 healthy controls. In the group of patients we analyzed the presence of risk factors for NHL and parameters of morbidity and disease severity. The Q192R polymorphism of the PON1 and PON2 polymorphisms (A148G and S311C) did not differ between groups and did not correlate with the parameters analyzed. The 55MM genotype and the 55M allele were more frequent in the CVID group than in control group. The arylesterase activity was similar in patients and controls showing a positive correlation with HDL levels. Patients with genotype 55MM had lower PON1 activity, associated with increased morbidity of the disease represented by the higher frequency of respiratory infections and a higher rate of hospitalization. The 55MM genotype also was correlated with the presence of risk factors for NHL, such as lymphoid nodular hyperplasia (HNL) and lymphadenopathy. Moreover, analysis of the alleles showed that less morbidity of the disease was associated with the presence of the allele 55L, which was correlated with a lower frequency of HNL and lymphadenopathies and fewer deaths. The 55M allele was correlated with a family history of immunodeficiency and hematological malignancies. CONCLUSION: This is the first report showing a greater frequency of 55MM genotype and 55M allele in patients with CVID. Our results suggest that the presence of 55L allele may be associated with a better prognosis. Conversely, these results suggest that patients with the 55MM genotype show higher morbidity and, possibly, higher risk for NHL