L’infection chronique par Helicobacter pylori touche plus de la moitié de la population mondiale et est la principale cause connue de l’adénocarcinome gastrique. La metformine, un antidiabétique oral, est de plus en plus étudiée pour ses propriétés antitumorales dans de nombreux types de cancers. Cependant, ses effets potentiels ont très peu été étudiés dans le cancer gastrique. Des expériences réalisées sur des lignées cellulaires cancéreuses gastriques et des tumeurs de patients amplifiées par xénogreffe chez la souris (PDX), ont permis de confirmer les propriétés antitumorales de la metformine. La metformine, en traitement préventif et curatif, diminue la capacité de formation des tumorsphères, l’expression des marqueurs de CSC gastriques, et la capacité d’auto-renouvellement propre aux CSC. Dans un second temps, nous avons montré que la metformine est capable d’inhiber la croissance bactérienne de H. pylori invitro et in vivo. Enfin, les effets de l’infection par H. pylori ont été étudiés sur la voie de signalisation mTOR par la réalisation d’une analyse transcriptomique et de western-blots sur des lignées cellulaires gastriques. Ceci a permis de démontrer que H. pylori inhibe le complexe mTORC1.Pour conclure, ce travail de thèse a permis i) de démontrer la capacité de la metformine à cibler les CSC gastriques, ii) de découvrir une nouvelle propriété antibactérienne de la metformine vis-à-vis de H. pylori, iii) de démontrer que H. pylori inhibe la voie de signalisation mTOR. / Chronic infection with Helicobacter pylori affects more than half of the world's population and is the main known cause of gastric adenocarcinoma. Metformin is an oral antidiabetic drug used to treat type 2 diabetes patients, and is being increasingly studied for its antitumoral properties in several cancer types. However, its potential effects in gastric cancer have not been thoroughly studied. Experiments performed on gastric cancer cell lines and patient-derived gastric carcinoma xenografts (PDX), have confirmed the antitumoral properties of metformin. Metformin, in preventive and curative treatment, decreases the tumorsphere formation, the expression of gastric CSC markers and the self-renewal capacity of CSC. In a second time, we have shown that metformin is able to inhibit the bacterial growth of H. pylori in vitro and in vivo. Finally, the effects of the H. pylori infection have been studied on the mTOR signaling pathway using a transcriptomic analysis and western blots, performed on gastric cancer cell lines. These show the ability of H. pylori to inhibit mTORC1.To conclude, this thesis work allowed i) to demonstrate the ability of metformin to target gastric CSCs, ii) to discover a new antimicrobial property of metformin against H. pylori, iii) to demonstrate that H. pylori inhibits the mTOR signaling pathway.

Therapy resistance of malignant cells represents the main reason responsible for the failure of cancer therapy. The growth of malignant cells at primary tumour sites but most importantly the dissemination of tumour cells and their growth at secondary sites, are the main reasons why patients eventually succumb to the disease. Even novel immune-based therapies find their limitation in most tumour types. The therapy resistance is mediated by the tumour cells but also by other cellular components of the tumour microenvironment. Understanding the tumour cells mechanisms and the tumour microenvironment features responsible for therapy resistance enables the development of novel therapeutic strategies. Here, we show that ionizing irradiation, 5-azacytidine, and IFNγ treatments induced expression of suprabasin (SBSN) and therapy-resistant low-adherent phenotype in cancer cells. Knockdown of SBSN resulted in suppression of the phenotype. Next, we identified aberrantly elevated SBSN in the bone marrow of a subgroup of myelodysplastic syndromes (MDS) patients. SBSN was expressed by myeloid-derived suppressor cells (MDSCs) and showed significant anti-correlation with T cell abundance and CCL2 levels, hence promises a prognostic value in clinical use. We compiled the most of the relevant knowledge of SBSN...

Genetisch bedingte Veränderungen im Wnt-Signalweg sind in der Tumorigenese des Darms von zentraler Bedeutung. Mutationen des Wnt-Effektormoleküls β-Catenin in den adulten Stammzellen des Darmepithels führen zu unkontrollierter Proliferation und Expansion der Darmstammzellen und initiieren die Tumorentstehung. Auch in fortgeschrittenen Darmtumoren unterstützt die Wnt-Signalgebung maßgeblich das Tumorwachstum und den Erhalt von Tumorstammzellen. Nach erfolgreicher chemotherapeutischer Behandlung treten oftmals Tumorrezidive auf, für deren Entstehung therapieresistente Tumorstammzellen verantwortlich gemacht werden. Trotz intensiver Forschung fehlen in der Darmkrebstherapie nach wie vor Behandlungsansätze zur gezielten Therapie der Tumorstammzellen. Ziel dieser Dissertation ist es, unser Verständnis der molekularen Regulationsmechanismen in Kolonkarzinomen zu erweitern und die Entwicklung rationaler Behandlungsstrategien zu fördern. Ich konnte die Histonmethyltransferase Mll1 als entscheidenden Faktor in der epigenetischen Regulation humaner und muriner Darmkrebsstammzellen und -tumore identifizieren. Humane Kolonkarzinome weisen eine erhöhte Mll1-Expression auf, die mit dem Level an nukleärem β-Catenin korreliert. Im adulten Darmepithel ist Mll1 insbesondere in den Lgr5+ Stammzellen exprimiert und maßgeblich an der Wnt/β-Catenin-induzierten Stammzellexpansion sowie der Tumorentstehung beteiligt. Der konditionelle Verlust von Mll1 im murinen Darmkrebsmodell verhindert die β-Catenin-induzierte Tumorigenese. Mll1 unterstützt die Selbsterneuerungsfähigkeit und Proliferation der Tumorstammzellen, indem es die Expression von essentiellen Stammzellgenen wie dem Wnt-abhängigen Stammzellmarker Lgr5 aufrechterhält. Eine Inhibition der Mll1-Funktion in der Darmkrebstherapie kann eine gezielte Eliminierung der Tumorstammzellen ermöglichen, wodurch das fortschreitende Tumorwachstum unterbunden und die Bildung von Rezidiven verhindert werden kann. / Genetic mutations inducing aberrant activity of Wnt signalling are causative for intestinal tumorigenesis. Mutations of the Wnt effector molecule β-catenin in adult stem cells of the intestinal epithelium drive uncontrolled proliferation, expand the stem cell pool and initiate tumor formation. In advanced tumors, aberrant Wnt signalling promotes tumor growth and maintains cancer stem cells. The cancer stem cells are highly resistant to conventional chemotherapy and frequently initiate tumor relapse after completion of treatment. Despite extensive research, we are still lacking efficient therapies for colon cancer that specifically eliminate the cancer stem cells. This dissertation aims to expand our knowledge on molecular gene regulatory mechanisms in colon cancer cells to promote the identification and future development of rational therapies for colon cancer patients. I identified the histone methyltransferase Mll1 as an epigenetic regulator in human and mouse intestinal cancer stem cells and tumors. Human colon carcinomas with nuclear β-catenin exhibit high levels of Mll1. In the adult intestinal epithelium of mice, Mll1 is highly expressed in the Lgr5+ stem cells and is a prerequisite for the oncogenic Wnt/β-catenin-mediated stem cell expansion and tumorigenesis. Conditional knockout of Mll1 in an intestinal mouse tumor model prevents the β-catenin-driven intestinal tumorigenesis. Knockdown of Mll1 impairs the self-renewal and proliferation of colon cancer sphere cultures and halts tumor growth in xenografts. Mechanistically, Mll1 sustains the expression of intestinal stem cell genes including the Wnt/β-catenin target gene Lgr5 by antagonizing gene silencing through polycomb repressive complex 2-mediated H3K27 tri-methylation. Interfering with Mll1 function can efficiently eliminate colon cancer stem cells, and has potential as a rational therapy for colon cancer.

Castration-resistant prostate cancer (CRPC) remains an aggressive incurable disease in men mainly due to treatment resistance. Current treatments do not effectively eradicate cancer stem cells (CSCs), which play a pivotal role in tumour maintenance, progression and drug resistance. Aldehyde dehydrogenases (ALDHs) have been used in some tumour types as CSC markers. Their high expression and high functional activity found in CSCs is also associated with drug resistance. Emerging evidence suggests deregulation of certain ALDH isoforms have implications in cancer. The role of ALDHs in prostate cancer as potential biomarkers and therapeutic targets has not been fully explored yet. Accordingly, this study investigated the expression, regulation and function of selected ALDH isoforms in prostate cancer. This study showed that ALDH1A3, ALDH1B1, ALDH2 and ALDH7A1 are highly expressed in primary prostate cancer cells (n=9) compared to benign (n=9) prostate cells. The expression of ALDH1A3 was high in the stem cells (SCs) (n=3) as well as the more differentiated counterparts (n=16). Treatment of both benign and malignant primary prostate cancer cells with all-trans retinoic acid (atRA) also resulted in increased expression of ALDH1A3 and ALDH3A1, supporting a feedback loop between atRA and ALDHs. Furthermore, SerBob, Bob and LNCaP cells were sensitive to treatment with epigenetic drugs and led to significantly higher expression of ALDH1A2, ALDH3A1 and ALDH7A1 respectively. Importantly, siRNA suppression of ALDH1A3 and ALDH7A1 led to reduced SC properties of primary prostate cultures including reduced cell viability, migration and colony formation, and increased differentiation of transit amplifying (TA) cells to committed basal (CB) cells. Novel ALDH-affinic probes showed reduced cell viability of primary prostate epithelial cultures as a single agent and also when used in combination with docetaxel. The results indicate the potential of using ALDH-affinic compounds as single agents for therapeutic intervention or in combination with docetaxel to sensitise resistant cells to this anticancer drug. The data in this thesis provides novel findings, which supports ALDH1A2, -1A3 and -7A1 as potential biomarkers and/or therapeutic targets for drug intervention. Although, a study analysing a larger number of samples is necessary to fully understand ALDH isoform expression in CSC, TA and CB cells it is envisaged that an ALDH-targeted therapy have potential in future treatment strategies for prostate cancer. / Prostate Cancer UK

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[ES] A pesar de los nuevos avances en el tratamiento del cáncer de pulmón, su tasa de incidencia y mortalidad siguen en cabeza en todo mundo. Concretamente, el cáncer de pulmón no microcítico (CPNM) representa casi el 85% de todos los cánceres de pulmón, siendo su supervivencia a 5 años muy reducida. En base a dicho escenario, el objetivo principal de este trabajo es el de caracterizar de manera exhaustiva los exosomas secretados por las células del CPNM. Se sabe que estas microvesículas están involucradas en números procesos celulares, por lo que pueden contener gran cantidad de información acerca de las características moleculares del tumor. Para ello se han empleado cultivos primarios y líneas comerciales crecidas en diferentes condiciones, así como muestras de sangre periférica obtenida de los pacientes con CPNM. Un primer screening llevado a cabo en los exosomas secretados in vitro, ha permitido obtener un gran número de mRNAs y miRNAs relacionados con diferentes procesos biológicos y vías de señalización. Además, algunos genes como FDFT1 y SNAI1 han destacado por su sobreexpresión en exosomas procedentes de las células crecidas en formación de tumoresferas (modelos 3D), las cuales están enriquecidas en población de células madre tumorales. A su vez, otros marcadores presentes en el interior de estas microvesículas, se han mostrado relacionados con dos de los subtipos histológicos más frecuentes: adenocarcinoma (LUAD) y carcinoma escamoso (LUSC). Posteriormente, para validar los hallazgos obtenidos en exosomas, los marcadores más significativos fueron analizados in silico en una cohorte de muestras de tejido, compuesta por 661 pacientes con CPNM (TCGA database). Estos resultados han revelado una asociación entre la expresión del gen SNAI1 y la supervivencia de estos pacientes (OS y RFS p<0.05). Además, los genes XAGE1B, SEPP1 y TTF-1 (previamente determinados en exosomas), mantienen una relación significativa con el grupo de pacientes LUAD; mientras que CABYR, RIOK3 y CAPRIN1 se mantienen sobrexpresados en LUSC (Mann-Whitney test p<0.05). Estos marcadores también se han analizado en una cohorte de 186 pacientes con CPNM procedentes del Hospital General Universitario de Valencia, donde se corroboró la asociación de SNAI1 con la supervivencia de los pacientes en estadios tempranos (RFS en pacientes LUAD, p<0.05), así como la sobreexpresión de CABYR y RIOK3 en pacientes LUSC, y de XAGE1B y TTF-1 en LUAD. Por otra parte, el aislamiento de los exosomas presentes en la sangre periférica de pacientes en estadios avanzados, ha permitido identificar otros marcadores asociados a caracterísiticas clínico-patológicas relevantes. A su vez, el contenido de estas microvesículas ha sido empleado para la detección de mutaciones génicas ligadas al manejo clínico del CPNM. En resumen, los resultados obtenidos en este trabajo ponen de manifiesto el potencial de los exosomas como fuente de biomarcadores para el estudio de las diferentes etapas de desarrollo del CPNM. Estas microvesículas ofrecen una visión completa y en tiempo real, de las características de la enfermedad, pudiendo ser aisladas de forma repetida y mediante técnicas mínimamente invasivas. / [CA] A pesar dels avanços recents en el tractament del càncer de pulmó, les seues taxes d'incidència i mortalitat continuen sent altes a nivell mundial. Concretament, el càncer de pulmó de cèl·lules no petites (CPNM) representa gairebé el 85% de tots els càncers de pulmó, amb una taxa de supervivència a 5 anys molt limitada. Donat aquest escenari, l'objectiu principal d'aquest estudi és caracteritzar de manera exhaustiva els exosomes secretats per les cèl·lules de CPNM. Aquestes microvesícules estan involucrades en nombrosos processos tumorals i poden contenir una gran quantitat d'informació sobre les característiques moleculars de la malaltia. Per aconseguir-ho, es van utilitzar cultius primaris i línies cel·lulars (cultiu en diferents condicions), juntament amb mostres de sang perifèrica obtingudes de pacients amb CPNM. Un cribratge inicial en exosomes secrets in vitro va permetre identificar una quantitat significativa de mARNs i miARNs relacionats amb diversos processos biològics i vies de senyalització. A més, alguns gens com FDFT1 i SNAI1 van destacar per la seua sobreexpressió en exosomes derivats de cèl·lules crescuts en formació de tumorsferes (models 3D), que estan enriquides en poblacions de cèl·lules mare tumorals. A més, s'han trobat marcadors en aquestes microvesícules associats amb dos dels subtipus histològics més comuns: adenocarcinoma (LUAD) i carcinoma escamós (LUSC). Posteriorment, per validar els resultats obtinguts en exosomes, es van analitzar in silico els marcadors més significatius en una cohort de teixit de CPNM de la base de dades TCGA. Aquests resultats van revelar una associació entre l'expressió del gen SNAI1 i la supervivència dels pacients (OS i RFS, p <0,05). A més, l'expressió dels gens XAGE1B, SEPP1 i TTF-1 (prèviament identificats en exosomes) va mantenir una relació significativa amb el grup LUAD, mentre que CABYR, RIOK3 i CAPRIN1 van continuar sobreexpressats en els pacients de LUSC (prova de Mann-Whitney, p <0,05). Aquests marcadors també es van analitzar en una cohort de 186 pacients amb CPNM de l'Hospital General Universitari de València, on es va confirmar l'associació de l'expressió de SNAI1 i la supervivència dels pacients en estadi precoç (RFS en pacients de LUAD, p <0,05), així com la sobreexpressió de CABYR i RIOK3 en pacients de LUSC, i de XAGE1B i TTF-1 en LUAD. D'altra banda, els exosomes presents en mostres de sang de la cohort d'estadis avançats van permetre la identificació d'altres biomarcadors associats a característiques clíniques rellevants dels pacients. A més, la càrrega exosomàtica també es va utilitzar per detectar mutacions genètiques relacionades amb el tractament clínic del CPNM. En resum, els resultats obtinguts en aquesta tesi destaquen el potencial dels exosomes com a font de biomarcadors per a l'estudi de les diferents etapes del desenvolupament del CPNM. Aquestes microvesícules ofereixen una visió completa i en temps real de les característiques moleculars de la malaltia i poden ser obtingudes de manera repetida i amb una mínima invasió. / [EN] Despite recent advancements in lung cancer treatment, its incidence and mortality rates remain high worldwide. Specifically, non-small cell lung cancer (NSCLC) accounts for nearly 85% of all lung cancers, with a 5-year survival rate of 20%. Given this scenario, the primary objective of this study is to comprehensively characterize the exosomes secreted by NSCLC cells. These microvesicles are known to be involved in numerous tumoral processes, potentially containing a wealth of information about the molecular characteristics of the disease. To achieve this, primary cultures and cell lines, along with peripheral blood samples obtained from NSCLC patients were used. An initial screening in exosomes secreted in vitro allowed the identification of a significant number of mRNAs and miRNAs, related to various biological processes and signaling pathways. Moreover, some genes such as FDFT1 and SNAI1 stood out due to their overexpression in exosomes derived from cells grown in tumorspheres formation (3D models), which are enriched in cancer stem cell population. Additionally, markers found within these microvesicles were associated with two of the most common histological subtypes: adenocarcinoma (LUAD) and squamous cell carcinoma (LUSC). Subsequently, to validate the findings seen in exosomes, the most significant markers were analyzed in silico in an NSCLC tissue cohort from the TCGA database. These results revealed an association between the expression of SNAI1 and patient survival (OS and RFS, p<0.05). Furthermore, XAGE1B, SEPP1, and TTF-1 expression (previously identified in exosomes) maintained a significant relationship with the LUAD group, while CABYR, RIOK3, and CAPRIN1 remained overexpressed in LUSC patients (Mann-Whitney test, p<0.05). These markers were also analyzed in a cohort of 186 NSCLC patients from the University General Hospital of Valencia. The association of SNAI1 expression and the survival of early-stage patients (RFS in LUAD patients, p<0.05) was confirmed, as well as the overexpression of CABYR and RIOK3 in LUSC patients, and of XAGE1B and TTF-1 in LUAD. Furthermore, exosomes present in blood samples of the advanced-stage cohort, allowed the identification of other biomarkers associated with clinically relevant characteristics of the patients. Moreover, exosomal cargo was also used to detect gene mutations related to the clinical management of NSCLC. In summary, the results obtained in this thesis highlight the potential of exosomes as a source of biomarkers for the study of the different stages of NSCLC development. These microvesicles offer a comprehensive and real-time view of the disease's molecular features and can be obtained repeatedly and in a minimally invasive way. / Duréndez Sáez, ME. (2024). Liquid Biopsy in non-small cell lung cancer: exosomes as a tool for the study of biomarkers [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/203438

Le glioblastome multiforme (GBM) est la tumeur cérébrale la plus commune et létale chez l’adulte. Malgré les avancés fulgurantes dans la dernière décennie au niveau des thérapies contre le cancer, le pronostique reste inchangé. Le manque de spécificité des traitements est la cause première de la récurrence de cette tumeur. Une meilleure compréhension au niveau des mécanismes moléculaires et biologiques de cette tumeur est impérative. La découverte des cellules souches cancéreuses (CD133+) au niveau du GBM offre une nouvelle opportunité thérapeutique contre cette tumeur. Effectivement, les cellules CD133+ seraient responsables de l’établissement, le maintien et la progression du GBM. De plus, elles sont également la cause de la résistance du GBM faces aux traitements de radiothérapies. Ces cellules représentent une cible de choix dans le but d’éradiquer le GBM. L’oncogène BMI1 a été associé à plusieurs types de tumeurs et est également essentielle au maintien de différentes populations de cellules souches normales et cancéreuses. Une forte expression de BMI1 est observée au niveau du GBM et plus précisément, un enrichissement préférentiel de cette protéine est noté au niveau des cellules CD133+. L’objectif principal de cette thèse est d’évaluer le rôle potentiel de BMI1 dans le maintien et la radiorésistance des cellules souches cancéreuses (CSC), CD133+ du GBM. La fonction principale de BMI1 est la régulation négative du locus INK4A/ARF. Ce locus est impliqué dans l’activation de deux voies majeurs anti-tumorales : P53 et RB. Or, la perte de BMI1 induit in vitro une diminution des capacités prolifératives, une augmentation de la différentiation et de l’apoptose, ainsi qu’une augmentation de la radiosensibilité des CSC du GBM indépendamment de la présence du locus INK4A/ARF. Effectivement, deux tumeurs sur trois possèdent une délétion de ce locus, ce qui suggère que BMI1 possède d’autre(s) cible(s) transcriptionnelle(s). Parmi ces nouvelles cibles ont retrouve la protéine P21, un régulateur négatif du cycle cellulaire. De plus, la perte de BMI1 inhibe l’établissement d’une tumeur cérébrale lors d’études de xénogreffe chez la souris NOD/SCID. Également, une nouvelle fonction de BMI1 indépendante de son activité transcriptionnel a été démontrée. Effectivement, suite à l’induction d’un bris double brin (BDB) de l’ADN, BMI1 est rapidement recruté au niveau de la lésion et influence le recrutement des protéines de reconnaissance du dommage à l’ADN. La perte de BMI1 mène à un défaut au niveau de la reconnaissance et la réparation de l’ADN, alors que sa surexpression induit plutôt une augmentation de ces mécanismes et procure une radiorésistance. Ces résultats décrivent pour la première fois l’importance de BMI1 au niveau du maintien, de l’auto-renouvellement et la radiorésistance des CSC du GBM. Ainsi, ces travaux démontrent que la protéine BMI1 représente une cible thérapeutique de choix dans le but d’éradiquer le GBM, une tumeur cérébrale létale. / Glioblastoma multiform (GBM) is the most common and lethal primary brain tumor found in adults. Despite the advances made in the field of cancer therapy in the last decade, the median survival rate remains less than a year. Therefore, a better understanding of the molecular biology of GBM will reveal the mechanisms responsible for the initiation and progression of the tumor, and allow the development of new therapeutic strategies. GBM contains a minority cell population, characterized by tumor initiating cells expressing the stem cell marker, CD133. The CD133+ GBM cells are responsible for tumor initiation, maintenance, progression and resistance to chemo/radiotherapy. The CD133+ cells represent a valuable and specific therapeutic target against GBM. The Polycomb (PcG) group family of transcriptional repressors have been involved in a vast range of cancers. The PcG protein and oncogene BMI1 is the best-characterized PcG protein. The implication of BMI1 in normal and cancer stem cell survival, self-renewal and maintenance has been thoroughly investigated. BMI1 is highly expressed in GBM and more precisely; it is enriched specifically in CD133+ cell populations. The main goal of this thesis was to elucidate the potential role of BMI1 in GBM CD133 + cancer stem cell (CSC) maintenance and radioresistance. The main function of BMI1 is to repress the expression of the genes encoded by the INK4A/ARF locus, which is implicated in the activation of two major tumor suppressor pathways, P53 and RB. However, BMI1 depletion in vitro induces a reduction in proliferation potential, as well as an increase in differentiation, apoptosis, and radiosensitivity regardless of INK4A/ARF status. Indeed, two-thirds of all tumors posses a deletion of this locus, suggesting that BMI1 regulates other targets. P21, a cell cycle regulator, was identified as a new BMI1 target. Moreover, we have observed that the loss of BMI1 inhibits the establishment of a cerebral tumor in a xenograft mouse model. In addition to transcription related activity, we identified a new transcription independent function of BMI1. After the induction of a DNA double-strand-break, BMI1 is rapidly recruited to the damage site and influences the recruitment of DNA damage response proteins. Furthermore, defects in DNA damage recognition and repair are observed after BMI1 knockdown. Consistent with these results, BMI1 overexpression induces DNA damage response and increases radioresistance potential. These results emphasize for the first time the requirement of BMI1 for the maintenance, self-renewal, and radioresistance in GBM CSC, thus providing a potential target for future therapeutic strategies against GBM.

The Diploma Thesis deals with an implementation of the new method for an assessment of a cloning efficiency of the cancer stem cells separated by a high speed cell sorter. The cell-sowing on the microtitration plates was performed by the flow cytometry method in a combination with the high speed cell sorter. In the first part of the Diploma Thesis the new method was introduced and tested on the selected cell lines. The obtained results were compared with the results of the limiting dilution assay within four cell lines. As for the second part of my Diploma Thesis, the method was practically applied to analysis of the cloning capacity of two subpopulations of cE2 cells based on the expressions of characteristic markers of stem and cancer stem cells - CD44 and CD 133. Based on the findings, the new method can be introduced as an approved proceeding for the cloning capacity assessment of cancer stem cells in other workplaces that possess analogical device equipment.

L'incidence, le coût et l'issue fatale dans un nombre encore trop élevé de cas font du cancer un problème majeur en santé publique. Malgré les progrès réalisés dans le développement de thérapies ciblées, la plupart des cancers rechutent, vraisemblablement à cause de l'échappement des cellules souches cancéreuses (CSC) qui survivent et régénèrent la tumeur. L'enjeu clinique en cancérologie aujourd'hui est d'éliminer les cellules souches cancéreuses en épargnant les cellules souches normales. Pour atteindre cet objectif, il est primordial de comprendre leurs mécanismes spécifiques de transformation. Nous évaluons dans mon équipe de recherche l'implication du microenvironnement dans la transformation et la résistance des CSC épithéliales, à travers les effets de facteurs solubles et de contacts cellulaires : l'enzyme CD10, et la voie des BMPs (Bone Morphogenetic Proteins).Notre équipe étudie le rôle du dialogue permanent entre la CS normale et son microenvironnement qui régule la prolifération, et la survie des CS. Nous utilisons la glande mammaire et la prostate comme systèmes modèles car ces deux types d'épithélium présentent des similitudes, ce qui nous permet d'aborder la question de l'apparition et la résistance des CSC dans deux modèles tumoraux correspondants. Des dérégulations de la voie des BMPs, comme de l'enzyme CD10 sont observées dans ces tumeurs. Enfin, nous cherchons à comprendre comment les dérégulations de la voie des BMPs apparaissent, en s'intéressant principalement aux facteurs pouvant modifier directement le microenvironnement, tels que les polluants présents dans l'environnement (bisphénols, benzoapyrène) / It has been shown for a number of cancers that a cell population characterized by stem cell (SC) properties and therapeutic resistance is likely responsible for relapse several years after treatment. Current therapies kill most of the tumor cells, but fail to eradicate the so-called cancer stem cells (CSC). Therefore a complete cure of the disease will require the eradication of the tumor-sustaining CSC. We propose to study these CSC in the context of breast cancer as the existence of CSC as already been highlighted in this epithelia.CD10 is a membrane enzyme able to cleave several peptide of the microenvironment (such as oxytocin, bombesin, enkephalin.. ) that can also interact with intracellular signalling pathway through its direct interaction with PTEN. Our results, and those of the literature, indicate that CD10 enzyme controls the fate of SC and is deregulated in normal breast and cancerous tissues. We showed that CD10 membrane expression allows the maintenance of immature cells partly through its enzymatic function that inhibits mammary stem cells differentiation. As CD10 has been described in breast cancer initiation, progression and resistance, we then decided to test the role of CD10 in tumor context. Our strategy consists in flow cytometry cell sorting for CD10+/CD10- cells to compare the functional properties of both sub-population. Only CD10+ cells are able to regenerate both CD10+ and CD10- subpopulations, and CD10+ cells exhibit higher expression of immature genes. Interestingly, modulating CD10 using stable expression of CD10 in our models and Sh strategies do not mimick the normal functions of CD10, indicating that CD10 could be more a marker of a certain population with immature properties prone to transformation rather than a driver. To better characterize the role of CD10 in luminal breast transformation, we developed a new human mammary model, initiated from immature cells to obtain transformed luminal epithelial cells and their resistant counterpart. We observed a higher level of CD10 expression during mammary epithelial cell transformation process. We then performed a microarray on CD10+ and CD10- subpopulations. Preliminary analysis seems to confirm that CD10 is a potential marker for a stem cell population prone to transformation rather than a direct driver of the cell transformation