The first case of breast implant-associated anaplastic large cell lymphoma (breast implant ALCL) was described by John Keech and the late Brevator Creech in 1997. In the following 2 decades, much research has led to acceptance of breast implant ALCL as a specific clinicopathologic entity, a process that we bring up to life through the memories of 6 persons who were involved in this progress, although we acknowledge that many others also have contributed to the current state of the art of this disease. Dr. Keech recalls the events that led him and Creech to first report the disease. Ahmet Dogan and colleagues at the Mayo Clinic described a series of 4 patients with breast implant ALCL, and led to increased awareness of breast implant ALCL in the pathology community. Daphne de Jong and colleagues in the Netherlands were the first to provide epidemiologic evidence to support the association between breast implants and ALCL. Garry Brody was one of the first investigators to collect a large number of patients with the disease, present the spectrum of clinical findings, and alert the community of plastic surgeons. Roberto Miranda and L. Jeffrey Medeiros and colleagues studied the pathologic findings of a large number of cases of breast implant ALCL, and published the findings in 2 impactful studies in the medical oncology literature. The recognition and acceptance of this disease by surgeons, epidemiologists, and medical oncologists, working together, has led to subsequent studies on the pathogenesis and optimal therapy of this disease. / Revisión por pares

L'oncogène ALK (Anaplastic Lymphoma Kinase) est une tyrosine kinase constitutivement active, impliquée dans divers cancers, tels que les lymphomes anaplasiques à grandes cellules (LAGC), ou certains carcinomes bronchiques. Ces tumeurs sont traitées par chimiothérapie, ce qui n'est pas un traitement optimal (30% de rechutes, abaissement de la qualité de vie). Dans ce contexte, de nombreux inhibiteurs spécifiques de la tyrosine kinase ALK tels que le Crizotinib ont été développés et ont prouvé leur efficacité à la fois dans des modèles in vitro, in vivo ainsi que chez les patients. Néanmoins, le succès de cette thérapie ciblée est limité par l'apparition de résistances. Il est donc essentiel de mettre au jour de nouvelles stratégies thérapeutiques permettant de contrecarrer ces résistances. Récemment, l'autophagie, un processus catabolique intracellulaire de dégradation lysosomale, a été proposée comme nouvelle cible thérapeutique dans le traitement des cancers résistants aux inhibiteurs de tyrosine kinase. Le premier objectif de mon projet de thèse a été de caractériser ce processus autophagique dans les LAGC ALK+, en réponse à différents traitements. Nous avons montré que (1) l'autophagie était activée dans des lignées de LAGC en réponse à l'inhibition de ALK, (2) que cette autophagie jouait un rôle cytoprotecteur dans ce modèle et (3) que les traitements par chimiothérapies de ces cellules n'induisaient pas de réponse autophagique. Dans un deuxième temps, nous nous sommes intéressés à la régulation potentielle de l'autophagie par les microARNs. Nous avons montré que plusieurs microARNs, dont le miR-7, étaient sous-exprimés en réponse au traitement par le Crizotinib et que la réexpression ectopique de ce miR-7 permettait une potentialisation de l'effet du Crizotinib, par l'induction d'autophagie cytotoxique dans notre modèle. Nous avançons également l'hypothèse que le " switch " autophagique de la cytoprotection à la cytotoxicité, que nous observons pourrait s'expliquer par la régulation de l'expression de plusieurs protéines cibles de miR-7 telles que Bcl-2 ou c-Raf. Ainsi, l'ensemble de nos résultats nous permettent de mieux comprendre le rôle et la régulation de l'autophagie induite en réponse à l'inhibition de ALK dans les LAGC ALK+, et pourrait à terme contribuer à l'amélioration des thérapies actuelles de divers cancers dépendants de l'oncogène ALK. / The ALK oncogene (Anaplastic Lymphoma Kinase) is a constitutively activated tyrosine kinase implied in various cancers including Anaplastic Large Cell Lymphomas (ALCL), or some lung adenocarcinomas. The current operative treatment is standard chemotherapy, which is not optimal (30% of relapses, low quality of life). In this context, new specific ALK inhibitors such as Crizotinib have been developed, and have showed their efficiency in vitro, in vivo and in patients. However, the emergence of resistant mutations has been described. Thus, the identification of alternative therapies targeting new pathways appears as mandatory to counteract those resistances. In this context, autophagy, an intracellular catabolic lysosomal process, has been described as a new therapeutic target in the treatment of cancers resistant to tyrosine kinase inhibitors. The first aim of my project was to characterize the autophagic process in ALK+ ALCL, upon different treatments. We showed that (1) autophagy was activated in ALK+ ALCL cell lines in response to ALK inhibition (2) that this autophagy played a cytoprotective role in our model and (3) that treatment with chemotherapies did not trigger an autophagic response. In a second part of the project, we focused on the potential regulation of autophagy by microRNAs. We showed that several microRNAs including miR-7 were down-regulated upon Crizotinib treatment and that ectopic re-expression of this miR-7 potentiates the effects of Crizotinib by induction of cytotoxic autophagy in our model. We hypothesized that this switch in the role of autophagy from cytoprotection to cytotoxicity observed in our model, could be explained by the regulation of several protein targets of miR-7 such as Bcl-2 or c-Raf. Altogether, these results enable a better understanding of the role and regulation of autophagy induced upon ALK inhibition in ALCL, and could in the longer term, contribute to improvement of current therapies of cancers involving the ALK oncogene.

Lymphomas are neoplasms of the human immune system and can be divided into two categories, Hodgkin’s lymphoma (HL) and non-Hodgkin lymphoma (NHL). Anaplastic large cell lymphoma (ALCL) is a form of NHL that shares a common distinctive feature with HL, the overexpression CD30. The expression of cytokine receptor CD30 is restricted to proliferating B and T lymphocytes in healthy individuals while its overexpression is associated with several lymphoproliferative diseases such as ALCL and HL. The activation of CD30 via ligand or antibodies triggers various cellular responses ranging from apoptosis to cell proliferation and it is thought that the variable cellular response to CD30 activation may be due to cell surface levels of CD30. The human CD30 gene is regulated at the transcriptional level and previous studies characterising its promoter have identified several factors that regulate the expression this gene. However none of these identified factors explain for the high levels of CD30 observed in HL and ALCL. Therefore this study focused on the identification and functional analysis of transcriptionally active regions located up or downstream of the CD30 promoter region. The first aim for this study was to identify and characterise regions within the human CD30 gene that are involved in its transcriptional regulation. Phylogenetic footprinting identified several regions downstream of the CD30 promoter that displayed high levels of sequence homology indicating potential functional significance. Validation of these regions through two in vivo approaches, DNase 1 hypersensitivity assay and chromatin accessibility studies localised potential transcriptionally active regions to intron 1 of the CD30 gene.

Anaplastisch-großzellige Lymphome (ALCL) repräsentieren eine Untergruppe der peripheren T-Zell-Lymphome und können über das Vorhandensein einer Translokation, die das ALK-Gen betrifft, in ALK-positive und ALK-negative ALCL unterteilt werden. Präliminäre Daten implizieren eine starke Expression des Transkriptionsfaktors IRF4 bei ALCL-Patientenproben, unabhängig des ALCL-Subtyps. Allerdings war die Rolle von IRF4 bei der Pathogenese des ALCL bislang wenig verstanden. In unserer Studie konnten wir zeigen, dass eine shRNA-vermittelte Herunterregulation von IRF4 Zytotoxizität im ALCL-Zelllinienmodell induziert und in vivo das Tumorwachstum signifikant verlangsamt. Genexpressionsanalysen zeigten die globale Rolle von IRF4 im Genexpressionsnetzwerk des ALCL über die Deregulation essentieller zellulärer Prozesse, wie der Zellzykluskontrolle und der DNA-Reparatur, sowie bekannter onkogener Signalwege wie Notch oder MYC. Wir konnten zeigen, dass IRF4 direkt an der Expression des bekannten onkogenen Transkriptionsfaktors MYC beteiligt ist und bestätigten zusätzlich die Abhängigkeit der ALCL-Zelllinien von dessen Expression. Die pharmakologische Inhibierung von MYC führte zum Rückgang der Zellviabilität aller ALCL-Zelllinien. Zusammenfassend zeigen diese Resultate, dass die Expression von IRF4 essentiell für die Proliferation von ALCL-Zelllinien ist und dass die von IRF4 regulierte Expression von MYC ein vielversprechendes therapeutisches Ziel für die zukünftige Behandlung sowohl ALK-positiver als auch ALK-negativer ALCL-Patienten darstellt. / Anaplastic large cell lymphoma (ALCL) is a distinct entity of peripheral T-cell lymphomas. ALCLs can be divided into two subtypes with respect to the presence of translocations involving the ALK gene (ALK-positive and ALK-negative). It has been shown that the interferon regulatory factor 4 (IRF4) is highly expressed in both ALCL subtypes but its role in the pathogenesis of these lymphomas remained unclear. Our study reveals an addiction to the expression of IRF4 in cell lines of both ALCL subtypes. Furthermore, we were able to transfer this into an ALCL xenograft mouse model showing the significant impact of IRF4 deregulation on ALCL tumor growth in vivo. Gene expression profiling after IRF4 knockdown highlighted the function of IRF4 in anaplastic large cell lymphoma by significant downregulation of genes involved in essential cellular processes like cell cycle control and DNA repair as well as known targets of the oncogenic transcription factor MYC. We were able to identify MYC as a direct target of IRF4 in both ALCL subtypes and further studies revealed an addiction of ALCLs to MYC expression as well. Pharmacological inhibition of MYC was toxic to all tested ALCL cell lines, indicating that IRF4 and MYC signaling may represent promising targets for future therapies of patients diagnosed with anaplastic large cell lymphoma.