O câncer pediátrico é raro em números absolutos, porém quando comparado às incidências em adultos vem apresentando aumento nas taxas de incidência, exigindo um preparo do sistema de saúde para acompanhamento. Este acompanhamento não pode ser igual ao do adulto, visto que crianças possuem diferenças fisiológicas nas diferentes faixas etárias pediátricas. Sendo assim, estudos de utilização de medicamentos são importantes nesta população, a fim de promover o uso racional dos mesmos, bem como, garantir seu uso seguro e uma terapêutica eficaz. O presente estudo tem por objetivo avaliar as prescrições de antineoplásicos, na unidade de oncologia pediátrica de um hospital universitário de Porto Alegre, identificando os protocolos mais utilizados, e posteriormente contextualizando-os com o preconizado no referencial teórico. Foi realizado um estudo transversal prospectivo envolvendo internações realizadas na unidade de oncologia pediátrica do Hospital de Clínicas de Porto Alegre (HCPA). Foram analisadas 274 internações, das quais 40 eram primeira internação e 234 reinternações. A maioria dos pacientes tinha idade de 0 a 10 anos, uma discreta prevalência do sexo masculino, de raça/cor branca, residentes na mesorregião metropolitana. A principal forma de financiamento das internações foi o público, e a principal causa de internação foi o tratamento, sendo o mais frequente o quimioterápico. Foram analisados os protocolos utilizados durante as internações de pacientes com diagnóstico de Leucemia Linfocítica Aguda, Retinoblastoma e Sarcoma de Ewing. Os protocolos são conjunto de regras criadas a partir de grupos cooperativos ou da indústria farmacêutica, permitindo um maior conhecimento sobre os medicamentos utilizados na pediatria. A oncologia pediátrica com sua particularidade de ser uma doença culturalmente ligada ao óbito possui maior facilidade de estudos deste porte. Porém, ainda são necessários mais estudos de utilização destes medicamentos, a fim de agregar conhecimento aos protocolos de tratamento. / Pediatric cancer is rare in absolute numbers, but when compared to the incidence in adults has shown an increase in incidence rates, requiring a prepared system health for following. Pediatrics treatment can’t be the same as that of adults, because children have different physiological differences in pediatric age groups. Studies of medication use in this population are very important in order to promote the rational use of drugs, as well as to guarantee their safe use and effective therapy. The present study aims to evaluate the anticancer prescriptions in pediatric oncology unit of a university hospital in Porto Alegre, identifying the most used protocols, and contextualizing them later with the recommendations in the theoretical framework. A prospective cross-sectional study involving hospital admissions in the pediatric oncology unit of the Hospital de Clínicas de Porto Alegre (HCPA) was performed. We analyzed 274 admissions, which 40 were first admission and 234 were readmissions. These admissions most patients were aged 0 to 10 years, white race, a slight male prevalence, residing in Metropolitan Mesoregion. The financing the hospital admissions was public, and the maining cause of hospitalization was treatment, the most frequent being the chemotherapy. We analyzed the protocols used during the admissions of patients diagnosed with Acute Lymphocytic Leukemia, Retinoblastoma and Ewing's Sarcoma. Protocols are studies that allow a greater knowledge about medicines for pediatric use. The pediatric oncology with its characteristic of being a disease has culturally linked with death ease of studies of this size. However, more studies of medication use are still needed to use these drugs in order to knowledge to the treatment protocols.

Les sarcomes épithélioides sont caractérisés dans 85% des cas par une perte d'expression nucléaire de la protéine SMARCB1, codée par un gène suppresseur de tumeurs situés en 22q11 impliqué dans la génèse des tumeurs rhabdoides malignes. L'exploration par BAC-FISH (Bacterial Artificial Chromosome- Fluorescence In Situ Hybridization) d'une série de 40 sarcomes épithélioides a permis d'établir que cette perte d'expression était secondaire dans 85% des cas à des délétions homozygotes et a mis en évidence le premier cas de sarcome épithélioide associé à une délétion germinale de SMARCB1, altération jusqu'alors uniquement identifiée dans les tumeurs rhabdoides malignes. Nous avons par la suite testé le gène suppresseur de tumeurs SMARCA4 comme gène candidat impliqué dans les sarcomes épithélioides SMARCB1-conservés à partir d'une série rétrospective de 16 cas. SMARCA4 code la sous-unité ATPase du complexe BAF dont SMARCB1 représente une sous unité. Ce screening initial a permis d'identifier 6 cas de sarcomes SMARCA4-inactivés dont la localisation était exclusivement thoracique et dont les caractéristiques clinique et anatomopathologique stéréotypées ont permis le recrutement prospectif et rétrospectif de nouveaux cas. L'étude par RNA-sequencing d'une fraction de notre cohorte (n=13/19) a confirmé leur homogénéité transcriptomique et souligné leur parenté avec les tumeurs rhabdoides SMARCB1 et SMARCA4 déficientes. L'absence de mutation germinale fréquente (n=1/11) a fait proposer le terme de sarcome thoracique SMARCA4-déficient (SMARCA4-DTS) en proscrivant l'utilisation du qualificatif « rhabdoide ». La parenté transcriptomique de ces tumeurs laisse entrevoir des vulnérabilités thérapeutiques communes qui restent à identifier / Epithelioid sarcomas (ES) display loss of SMARCB1 nuclear expression in 85% of cases. SMARCB1 is encoded by a tumor suppressor gene located in 22q11 which was first linked to cancer in malignant rhabdoid tumors. While investigating a series of 40 epithelioid sarcomas with BAC-FISH (Bacterial Artificial Chromosome-Fluorescence In Situ Hybridization), we demonstrated that SMARCB1 loss in ES occurred through genomic deletions in 85% of cases. We were also able to highlight the first case of ES associated with a heterozygous SMARCB1 deletion in the germ line, which feature was previously thought to be restricted to malignant rhadboid tumors (MRT). We subsequently investigated a series of 16 SMARCB1-retained ES to identify its underlying culprit gene with a focus on the candidate tumor suppressor gene SMARCA4. SMARCA4 encodes one of the ATPase subunit of BAF complexes. Interestingly, SMARCB1 is also a core submit of these complexes which regulate chromatin remodeling. We were able to identify a set of 6 cases displaying SMARCA4 inactivation with this discovery cohort. The review of medical records highlighted these cases had similar presentation : all tumors presented with large compressive and aggressive mediastinopulmonary masses. We further recruited 13 cases based on these characteristics including 5 prospective cases. The characterization of their transcriptomes by RNA-sequencing (n=13/19) confirmed their remarkable homogeneity, all our samples clustering together with MRT. However our variant diverge from malignant rhabdoid tumors as it lacks SMARCA4 alteration in the germline (n=0/11) and displays complex polyploidy genetic profiles. We therefore called this new tumor variant “SMARCA4-deficient thoracic sarcoma” (SMARCA4-DTS). The transcriptomic vicinity of SMARCA4-DTS and MRT let foresee they share common therapeutic vulnerabilities

Purpose: Leiomyosarcoma of the urinary bladder is exceedingly rare. Most clinicians come across only a few cases during their career, and information regarding treatment and outcome is scattered in the scientific literature. Interested clinicians and patients have to undertake troublesome search for treatment and outcome information. Material and methods: We performed a systematic review of the literature using the PubMed and Web of Science databases and included all identified cases published in English language between 1970 and June 2018 into a meta-analysis. Prior to the literature search, key questions were formulated and with the data obtained, answers to these questions should be derived. Results: We analyzed clinical data of 210 cases of urinary bladder leiomyosarcoma revealed by this review and seen in our institution. The mean age of patients was 52 years. The majority (75%) of the tumors was classified as high-grade sarcomas. We found no report of a prior radiation therapy to the pelvic organs, but some authors suggested an association between cyclophosphamide treatment and the development of bladder leiomyosarcoma, especially in patients with retinoblastoma. For the whole sample, we determined 5- and 10-year cancer-specific cumulative mortality rates of 38 and 50%. Patients with high-grade sarcomas had a trend toward a higher mortality compared with lowgrade tumors (p = 0.0280). The most promising treatment option seems to be surgery (radical or partial cystectomy) with negative resection margins, possibly supplemented by chemotherapy or radiation. Conclusion: About half of patients with bladder leiomyosarcoma survived on the long run. Low-grade tumors may have a better outcome with, nevertheless, countable long-term mortality. For better assessment of that rare bladder tumor, its best treatment options, and the influence of neoadjuvant or adjuvant therapies on the outcome of patients, a larger series with longterm survival data is required.

Most viruses can infect only a reduced range of organisms and an effective replication is possible only in selected hosts. These hosts are called permissive for the virus. Molecular principles of a nonpermissiveness and viral mechanisms of overcoming replication obstacles are still not clearly elucidated. This thesis discusses the molecular causes of the cellular nonpermissiveness against a model retrovirus - Rous sarcoma virus. The research is conducted on duck cells which are semipermis- sive to the subgroup C of Rous sarcoma virus. The virus can enter those cells, but it is not able to produce enough infectious viral progeny. Two blocks of the viral replication cycle in the duck cells are described in the thesis. The first one is the probably not optimal cellular receptor recognition. The second one is in the late phase of the replication cycle when the viral proteins are synthesized. The amount of the envelope glyco- protein coding mRNA is reduced due to the altered splicing ratios, and the virions produced from the duck cells are less infectious. This block is recessive and can be partially omitted by cell fusions with permissive chicken cells; therefore, the block is not caused by specific restriction fac- tors in sensu stricto. Additionally, the influence of mutations in duck adapted Rous...

Contexte : Chaque année, au Canada, environ 1000 enfants âgés de 0 à 14 ans recevront un diagnostic de cancer. On estime qu’environ 80 % de ceux-ci vont survivre. La rémission implique un suivi à long terme basé sur la prévention et la promotion de la santé. Une fois adulte, ce type de suivi doit se poursuivre. Ces jeunes âgés de 18 ans devront donc effectuer un transfert de milieu de soins entre le centre pédiatrique et le centre adulte. Le passage à l’âge adulte étant déjà un moment de changement en soi, l’ajout de cette transition de milieu vers un milieu inconnu peut être anxiogène. Des patients qui ont une expérience acquise à naviguer dans le centre de cancérologie adulte pourraient venir en aide à leurs pairs sous forme d’accompagnement à la transition. Objectifs : Identifier les besoins spécifiques des patients en rémission d’une tumeur cérébrale diagnostiquée à l’enfance et qui devront transférer d’un centre pédiatrique à un centre adulte et ainsi, connaître leur intérêt face à une intervention comprenant un patient accompagnateur (PA). Identifier les facteurs favorables et limitants à la mise en place d’une intervention impliquant des PA lors de la transition vers un centre hospitalier adulte des patients en rémission d’un sarcome diagnostiqué à l’enfance. Puis, connaître la perception des parties prenantes qui gravitent autour de la transition de milieux de soins quant aux pistes d’amélioration à apporter, aux enjeux vécus, mais aussi à la possibilité d’impliquer des PA. Méthode : Un devis qualitatif de type exploratoire de faisabilité d’implantation est utilisé. Des entretiens sont conduits auprès de la population de recherche constituée de patients effectuant le transfert de milieu, d’un PA, de professionnels de la santé et des membres de bureaux du partenariat. L’analyse thématique est utilisée afin de faire ressortir les thèmes communs des entrevues autant pour les divergences de point de vue que pour les ressemblances. Résultats : Les membres des bureaux de partenariat voient des bénéfices à l’implication de PA, mais y voient certaines complexités vu le manque de ressource pour soutenir un tel programme. Ils accordent une importance particulière au suivi psychosocial des PA et l’implication des parents dans le processus. Quant aux professionnels de la santé, ils accordent une importance particulière au développement de l’autonomie des jeunes patients et un suivi conjoint entre les centres. Ils sont également sensibles au suivi psychosocial des patients et aux enjeux spécifiques à la transition. Ils voient des bénéfices à l’implication d’un programme de PA, mais soulèvent des réticences. Le patient nomme la différence d’encadrement entre les milieux et les difficultés de communication entre ceux-ci. Les lacunes de la communication transparaissent dans le transfert du dossier médical, une inquiétude soulevée par le patient. Il voit cependant des bénéfices à un programme impliquant des PA. Puis, le PA aborde les défis et les préalables à la réussite de ses interventions. Il soulève également le manque d’accompagnement pour les parents. Conclusion : La transition de milieux de soins génère de nouveaux défis pour les patients comme ceux diagnostiqués à l’enfance d’une tumeur cérébrale ou d’un sarcome. Une attention particulière doit être portée aux besoins de ces patients, mais aussi à l’amélioration du processus. De premier abord, l’implantation d’un programme de PA n’est pas ressortie comme un besoin exprimé par le patient. Il y voyait cependant que des bénéfices. Les données de cette étude sont trop restreintes pour déterminer si l’accompagnement serait bénéfique à la transition entre le milieu pédiatrique et adulte. Cependant, cette étude exploratoire de faisabilité d’implantation a permis de connaître les perceptions des parties prenantes qui gravitent autour de ce processus de transition entre les milieux face à des pistes d’amélioration du processus, des enjeux vécus et la perception de l’implication des PA. Mots clés: Tumeur cérébrale, sarcome, patient accompagnateur, transition de milieux de soins, pédiatrie, centre hospitalier universitaire Sainte-Justine, centre hospitalier universitaire de Montréal, hôpital Maisonneuve-Rosemont / Background: Every year, in Canada around 1000 kids between 0 and 14 years old will be diagnosed with a cancer. The survival rate is estimated around 80%. Remission involves a survivorship follow up based on prevention and health promotion. As an adult, their follow up must continue. The 18 years old young adult will transfer from pediatric care center to adult care center. Transition to adulthood is a turning point for them and the adding of adult care center transfer can be anxiety inducing. Patients who had experience navigating in the adult cancer care center can help reduce this anxiety by being mentor for the other patients. Objectives: Identify the needs of patients in remission from a brain tumor cancer diagnosed in childhood who will transfer from a pediatric center to an adult center and thus, know their interest in an intervention including a mentor patient. Identify the positive and limiting factors for the implementation of an intervention involving mentor patients during the transition to an adult hospital center for patients in remission from a sarcoma diagnosed in childhood. Then, know the perception of the stakeholders of the process as to the avenues for improvement to made, the issues experienced, but also the possibility of involving mentor patients. Design: A qualitative design of exploratory type of implementation feasibility is used. Interviews are conduct with patients, mentor patient, health care professionnal and paternership members. A content analysist is used to bring out the principal themes in the interviews and also the different and the similar points of view. Results: The members of the partnership offices clearly see the benefits of involving mentor patient but see certain complexities in it because of the lack of resources to support such program. They attach particular importance to the psychosocial follow-up of mentor patient and the involvement of parents in the process. As for health professionals, they attach a particular importance to the development of young patient’s autonomy and joint monitoring between the centers. They are also sensitive to the psychosocial follow-up of patients and to the specific issues of the transition. They see benefits in the involvement of a mentor patient program but raise some reservations. The patient raises the difference in supervision between the care centers and the communication difficulties between them. The gaps in communication are reflected in the transfer of the medical file, a concern of this patient. However, he sees only benefits to a program involving mentor patient. Then, the mentor patient discusses of the challenges and prerequisites for the success of his interventions. He also raises the lack of support for parents. Conclusion: The period when care environment change, being a time of new challenges for patients such as those diagnosed with a brain tumor or sarcoma in their childhood, special attention must be paid to their needs, by improving the process. At first, the implementation of a mentorship program did not emerge as a need expressed by the patient. However, he only saw benefits. The data from this study are too limited to determine whether mentor support would be beneficial to the transition between the pediatric and adult settings. However, this exploratory study made it possible to know the perceptions of the stakeholders who gravitate around this process of transition between the care centers which is improving the process, the issues experienced and the perception of the mentors’ patients. Key words: Brain tumor, sarcoma, mentor patient, transition of care settings, pediatrics, centre hospitalier universitaire Sainte-Justine, centre hospitalier de l’Université de Montréal, Maisonneuve-Rosemont hospital

This doctoral thesis describes unusual skin and soft-tissue tumors, which were the basis of the postgraduate study of Ladislav Hadravský, MD at Medical faculty in Pilsen of Charles University in Prague during 2013 - 2016. It contains documented cases of skin and soft-tissue tumors related to hereditary syndromes, unusual morphology, rare biological behavior, minor causal association with the respective disease, or different phenotypes. These cases were published in journals with the impact factor and in peer-reviewed journals. Regarding skin tumors, the study focused on sebaceous tumors of the skin, which may occur within Muir-Torre syndrome. In the retrospective study of sebaceous skin tumors, two unusual cases were found: the case of aggressive extraocular sebaceous carcinoma on the scalp in a patient with Muir-Torre syndrome and the case of multiple sebaceous skin tumors in a patient with MUTYH-associated polyposis of the colon mimicking Muir-Torre syndrome. As far as soft-tissue tumors are concerned, the study aimed at the morphological comparison of cases of myxoinflammatory fibroblastic sarcoma and pleomorhic hyalinizing angiectatic tumor.

L’objectif de cette thèse était d’étudier la distribution, les déterminants et les conséquences des délais diagnostiques des cancers de l’enfant, par une revue systématique de la littérature, une analyse des plaintes déposées en France et au Canada et par des études ad hoc en population sur les tumeurs ayant des délais particulièrement longs : le médulloblastome et le sarcome d’Ewing.La revue systématique n’a pas retrouvé de diminution significative de la longueur des délais au cours du temps. Les délais longs étaient associés à un âge élevé, au type histologique et à la localisation de la tumeur. Les relations entre délai et gravité de la maladie étaient variables. Seul un tiers des conclusions des expertises judiciaires (n = 56) étaient concordantes avec les données de la littérature.Le délai diagnostique médian des enfants atteints de médulloblastome en Ile-de-France (n = 166) était de 65 jours. Les délais longs étaient associés paradoxalement à des métastases moins fréquentes et à une histologie favorable, mais pas à la survie ni aux séquelles.Le délai diagnostique médian des enfants atteints de sarcome d’Ewing en France (n = 436) était de 70 jours. Les délais longs, liés à un âge élevé et à la localisation de la tumeur, n’étaient pas associés au volume tumoral, à la présence de métastases, à l’opérabilité ni à la survie.Pour certaines tumeurs, une association entre délais diagnostiques et gravité est établie (rétinoblastome) ou hautement probable. Pour d’autres, l’absence d’association démontrée permettrait de dédramatiser la perception de leurs conséquences, sans dispenser d’essayer de réduire ces délais, notamment pour en atténuer les conséquences psychologiques. / The aim of this thesis was to study the distribution, determinants and consequences of time to diagnosis of cancer in children, through a systematic review of the literature and an analysis of lawsuits in France and Canada, and two population-based studies of tumors with particularly long diagnosis delays: medulloblastoma and Ewing sarcoma.The systematic review did not identify any significant decreases in time to diagnosis during the studies. Long times to diagnosis were associated with older age, histological type and location of the tumor. Associations between time to diagnosis and severity of the disease varied. Only a third of the court-appointed experts (n = 56) provided testimony concordant with the available medical literature.The median time to diagnosis of children with medulloblastoma in the area of Paris (n = 166) was 65 days. Diagnosis delays were paradoxically associated with less frequent metastasis and favorable histology, but not with survival, or sequelae.The median time to diagnosis of children with Ewing sarcoma in France (n = 436) was 70 days. Diagnosis delays, related with older age and tumor location, were not associated with tumor size, presence of metastasis, surgical outcome, or survival.For some tumors, an association between time to diagnosis and severity of the disease is well established (e.g. retinoblastoma), or highly probable. For others, the lack of demonstrated associations could tone down the perception of the supposed consequences of diagnosis delays - but does not exempt from trying to reduce them, in order to alleviate their psychological consequences.

Les rétrovirus sont des virus à ARN, enveloppés présents dans de nombreuses espèces animales de rente, chez les animaux de compagnie et chez l’homme. Une des particularités des rétrovirus concerne l’intégration du génome viral au sein du génome de la cellule infectée; cette intégration est réalisée par une enzyme virale, l’intégrase. Le projet de cette thèse vise à mieux comprendre le fonctionnement de cette enzyme notamment en identifiant des facteurs cellulaires interagissant avec celle-ci, facteurs qui pourraient être des agents favorisant le processus intégratif ou, au contraire, des agents restrictifs. Les intégrases de deux modèles de rétrovirus ont été utilisées dans cette étude : L’intégrase de RAV1, un rétrovirus exogène aviaire du genre des alpharétrovirus appartenant au sous-groupe A de la famille des ASLV. Cette enzyme virale est largement étudiée soit au niveau structural ou fonctionnel, mais les données concernant ses partenaires cellulaires sont rares et insuffisantes. La seconde intégrase est celle du PERV A/C, un rétrovirus endogène porcin du genre gammarétrovirus. Aucune information sur cette enzyme n’a été décrite jusqu’à présent. Ces deux enzymes, en fusion avec une étiquette 6xHistidine, ont été donc produites en bactérie, et en cellules d’insecte puis purifiées sur colonne d’affinité en FPLC. Leurs activités catalytiques ont été testées in vitro. Ces tests permettent de valoriser la capacité de l’intégrase à exercer principalement les 2 fonctions dont elle est responsable in vivo, le clivage en 3’ et le transfert de brins, et une activité qu’elle exerce exclusivement in vitro, la désintégration. Les protéines pures et actives ont ensuite servies à la vérification de leur interaction avec une protéine cellulaire, Brd2. La technique ‘Far western blot’ a ainsi permis de valider l’interaction entre l’intégrase de PERV et la protéine cellulaire, puis d’identifier les domaines de l’intégrase et de Brd2 impliqués dans cette interaction. A terme, l’identification de ce facteur cellulaire et la validation de son rôle dans le processus intégratif permettront de mieux comprendre ce processus particulier développé par les rétrovirus et pourront conduire au développement d’inhibiteurs dirigés contre cette interaction / A critical step for retroviral replication is the stable integration of the provirus genome into the genome of its host; this integration is realized by a viral enzyme, the integrase. The aim of this work was to better understand the functioning of the integrase, particularly, by identifying host factors that might interact with it, and which could be factors favoring the integration process or, restrictive factors. Therefore, we used two models of retroviral integrases: The integrase of RAV1, an alpharetrovirus belonging to the subgroup A of the family of ALSV. Although this viral enzyme is widely studied, still not enough data are available about its cellular cofactors. The second enzyme studied here is the integrase of PERV, a gammaretrovirus. No studies of either PERV integrase activities in vitro or of proteins interacting with this viral enzyme have been available until now. In the present study, we have expressed the PERV and ALSV integrases as fusion proteins with a 6xHistidine Tag in both Escherichia coli and insect SF9 cells. After that, we analysed their ability to mediate catalytic activities (3’-end processing, strand transfer and disintegration) in vitro. We also investigated the interaction of these two viral enzymes with the cellular protein Brd2, using the Far western blot method. Our results validate Brd2 as a cofactor of PERV integrase and point to the important role of particular domains of the PERV integrase and Brd2 in mediating the interaction. Finally, this study contibute to a better understanding of the precise interaction between cellular proteins and integrase, and may lead in the future to the development of protein-protein interaction inhibitors

Le lymphome à cellules du manteau (LCM) est une hémopathie maligne B mature, appartenant à la famille des lymphomes non hodgkiniens. Le LCM est caractérisé par la translocation t(11;14)(q13;q32) qui provoque une expression aberrante de cycline D1. C’est une pathologie rare mais à haut risque de rechute, et qui reste le plus souvent incurable suite à l’apparition de clones chimiorésistants. L’acquisition de résistance est intimement liée aux interactions entre les cellules tumorales et leur microenvironnement. Afin de mimer de la manière la plus pertinente possible ces interactions, nous avons mis en place un modèle murin de xénogreffe en utilisant les lignées cellulaires de LCM JeKo1, REC1, Z138 et Granta-519 que nous avons modifiées afin qu’elles expriment un fluorophore (GFP ou m-cherry) et/ou le gène codant pour la luciférase. Après injection aux souris du substrat de la luciférase, la luciférine, nous sommes en mesure de suivre au cours du temps la progression tumorale. Nous pouvons également évaluer le degré d’infiltration tumorale dans la moelle osseuse, la rate, le cerveau et le sang après euthanasie des animaux, par des techniques de cytométrie en flux et d’immunocytochimie. Ce modèle nous a permis de montrer l’intérêt thérapeutique d’un inhibiteur de l’exportine 1 (XPO1) : le KPT 330 (ou selinexor) qui est capable de contenir cycline D1 uniquement au niveau nucléaire. Nous avons montré que la localisation subcellulaire de cycline D1, est retrouvée majoritairement cytoplasmique dans certaines lignées cellulaires de LCM (2/7) et chez un certain nombre de patients (6/42, 14%), et est associée à un fort potentiel d’invasion, de migration et à un phénotype agressif. Par ailleurs, grâce à ce modèle, nous avons pu objectiver le manque d’efficacité in vivo d’agonistes aux récepteurs aux œstrogènes de type β (ER β). Ces récepteurs, présents sur les lymphocytes B étaient supposés inhiber la prolifération cellulaire et provoquer la mort des cellules par apoptose. L’utilisation de deux agonistes des ER β, le diarylpropionitrile (DPN) et l’ERB-041 a montré une absence d’effet de ces molécules, lorsque les cellules tumorales sont au contact de leur microenvironnement. D’autre part, afin de mieux comprendre les mécanismes de résistance aux chimiothérapies, nous avons étudié la résistance de la lignée cellulaire REC-1 traitée par des agents génotoxiques. Nous avons montré que cette lignée présentait une anomalie de dégradation de cycline D1 associée à une activité diminuée du protéasome 26S. Enfin, nous avons montré dans des travaux préliminaires que la protéine fused in sarcoma (FUS) pourrait, lorsqu’elle est associée à cycline D1, être capable de réguler les voies de réparation des dommages à l’ADN. Des anomalies de ces voies induisent une grande instabilité génétique responsable de l’échappement des tumeurs aux traitements, le ciblage de FUS pourrait par conséquent présenter un intérêt thérapeutique.Pris dans leur ensemble, ces résultats permettent de renforcer ou d’infirmer l’intérêt de certaines cibles thérapeutiques dans l’espoir de pouvoir continuer à améliorer la prise en charge des patients. Ils fournissent également un outil pour l’évaluation de nouvelles molécules dans un modèle murin prenant en compte les interactions entre la cellule tumorale et son microenvironnement. / Mantle cell lymphoma (MCL) is a mature malignant hemopathy, belonging to the non-Hodgkin's lymphoma family. The MCL is characterized by the translocation t(11;14)(q13;q32) which causes an aberrant expression of cyclin D1. It is a rare disease but at high risk of relapse, and it is most often incurable due to the appearance of chemoresistant clones. The acquisition of resistance is intimately linked to the interactions between the tumor cells and their microenvironment. In order to mimic, in the most relevant way, these interactions, we have implemented a mouse xenograft model using the MCL cell lines JeKo1, REC1, Z138 and Granta-519 which we have modified so that they express a fluorophore (GFP or m-cherry) and / or the gene encoding the luciferase. After injection to the mice of the luciferase substrate, luciferin, we are able to follow over time the tumor progression. We can also assess the degree of tumor infiltration in bone marrow, spleen, brain and blood after euthanasia of animals, by flow cytometry and immunocytochemistry. This model allowed us to show the therapeutic interest of an inhibitor of exportin 1 (XPO1): the KPT 330 (or selinexor) which is able to contain cyclin D1 only on the nuclear level. We have shown that the subcellular localization of cyclin D1 is mainly cytoplasmic in some LCM (2/7) cell lines and in a number of patients (6/42, 14%), and is associated with a high potential Invasion, migration and an aggressive phenotype. Moreover, thanks to this model, we have been able to objectify the in vivo lack of efficacy of agonists to β-type estrogen receptors (ER β). These receptors, present on B lymphocytes, were thought to inhibit cell proliferation and cause cell death by apoptosis. The use of two ER β agonists, diarylpropionitrile (DPN) and ERB-041 showed an absence of effect of these molecules, when the tumor cells are in contact with their microenvironment. On the other hand, in order to better understand the mechanisms of resistance to chemotherapies, we studied the resistance of the REC-1 cell line treated with genotoxic agents. We have shown that this line has an abnormality of cyclin D1 degradation associated with decreased activity of the 26S proteasome. Finally, we have shown in preliminary work that the fused in sarcoma protein (FUS) could, when associated with cyclin D1, be able to regulate the repair pathways of DNA damage. Abnormalities of these pathways induce a great genetic instability responsible for the escape of tumors to treatments, the targeting of FUS could therefore be of therapeutic interest.Taken as a whole, these results reinforce or invalidate the interest of certain therapeutic targets in the hope of continuing to improve the management of patients. They also provide a tool for evaluating new molecules in a murine model that takes into account the interactions between the tumor cell and its microenvironment.

One of the important tasks of virology and immunology is to explore the species- and cell-barriers preventing virus horizontal transmission and reveal the ways how viruses overcome these barriers and "adapt" to different species. This work is based on a well- established retroviral model - avian Rous sarcoma virus (RSV) and studies virus replication blocks in mammalian cells at both pre- and post-integration level. Interaction of the viral envelope glycoprotein (Env) with a specific cellular receptor mediates virus entry into cells. Although mammalian orthologues of specific chicken receptors do not support RSV entry, it was observed that some RSV strains are able to enter mammalian cells. Several RSV-transformed rodent cells lines were described and analysis of provirus H20- RSV in one these cells lines (hamster H-20 tumor cell line) showed multiple mutations including two crucial amino acid substitutions in different regions of Env. Substitutions D32G and L378S confer virus transmission to hamster, human and also chicken cells lacking the appropriate receptor. Altered conformation of H20-RSV Env is similar to a receptor-primed (activated) state of Env. This observation indicates that virus can circumvent the need of original cell receptor because of spontaneous Env activation caused by single...