I ett försök att förstå orsakerna bakom de kardio-, metaboliska- och muskuloskeletala sjukdomar hos barn som överlevt akut lymfatisk leukemi (ALL) har vi studerat den adipogena differentieringen hos mesenkymala stromaceller från benmärg (BM MSCs). Det komplexa nätverket av faktorer som påverkar adipogenes är hittills inte helt kartlagt. Därför är vårt övergripande mål att få en bättre förståelse för den cellulära och molekylära grunden bakom utvecklingen av dessa tillstånd hos ALL-överlevare. Vi undersökte om behandling av BM MSC in vitro med cancerläkemedel, Doxorubicin och Dexamethason, kan påverka differentieringen mot adipogenes. BM MSCs analyserades med avseende på lipidackumulering, genuttryck och adipokinproduktion. Vår hypotes kunde inte bekräftas. Inga lipidackumuleringar kunde detekteras i cellerna. Vid analys av genuttryck av de adipogena transkriptionsfaktorerna PPARγ och C/EBPα sågs vissa förändringar; men på grund av brist på biologiska replikat kunde inga statistiska analyser tillämpas på resultaten. Slutligen sågs en liten ökning i den inflammation- och adipogenes-associerade cytokinen IL-6, medan cytokinerna IL-8 och TNF-a inte gick att detektera alls. / In an effort to understand the cause of late onset cardiac, metabolic, and musculoskeletal conditions in paediatric acute lymphoblastic leukaemia (ALL) survivors, the adipogenic differentiation of bone marrow (BM) mesenchymal stromal cells (MSCs) has been studied. There is a complex network of factors influencing adipogenesis, which to date is not completely understood. Hence, the overall aim is to better understand the cellular and molecular basis behind the development of these conditions in survivors. To this end, we asked whether treating BM MSCs in vitro with cancer drugs, Doxorubicin and Dexamethasone, will initiate a skewed differentiation towards adipogenesis. BM MSCs were analysed with respect to lipid accumulation, gene expression, and adipokine production. In general, our hypothesis was not confirmed. No lipid accumulations were detected in the cells. In analysis of gene expression of the adipogenic transcription factors PPARγ and C/EBPα, certain changes were seen; however, due to lack of biological replicates, no statistical analyses could be applied to the results. Lastly, the inflammation and adipogenesis associated cytokine IL-6 displayed a slight increase, whereas the cytokines IL-8 and TNF-α were undetectable.

I ett försök att förstå orsakerna bakom de kardio-, metaboliska- och muskuloskeletala sjukdomar hos barn som överlevt akut lymfatisk leukemi (ALL) har vi studerat den adipogena differentieringen hos mesenkymala stromaceller från benmärg (BM MSCs). Det komplexa nätverket av faktorer som påverkar adipogenes är hittills inte helt kartlagt. Därför är vårt övergripande mål att få en bättre förståelse för den cellulära och molekylära grunden bakom utvecklingen av dessa tillstånd hos ALL-överlevare. Vi undersökte om behandling av BM MSC in vitro med cancerläkemedel, Doxorubicin och Dexamethason, kan påverka differentieringen mot adipogenes. BM MSCs analyserades med avseende på lipidackumulering, genuttryck och adipokinproduktion. Vår hypotes kunde inte bekräftas. Inga lipidackumuleringar kunde detekteras i cellerna. Vid analys av genuttryck av de adipogena transkriptionsfaktorerna PPARγ och C/EBPα sågs vissa förändringar; men på grund av brist på biologiska replikat kunde inga statistiska analyser tillämpas på resultaten. Slutligen sågs en liten ökning i den inflammation- och adipogenes-associerade cytokinen IL-6, medan cytokinerna IL-8 och TNF-a inte gick att detektera alls. / In an effort to understand the cause of late onset cardiac, metabolic, and musculoskeletal conditions in paediatric acute lymphoblastic leukaemia (ALL) survivors, the adipogenic differentiation of bone marrow (BM) mesenchymal stromal cells (MSCs) has been studied. There is a complex network of factors influencing adipogenesis, which to date is not completely understood. Hence, the overall aim is to better understand the cellular and molecular basis behind the development of these conditions in survivors. To this end, we asked whether treating BM MSCs in vitro with cancer drugs, Doxorubicin and Dexamethasone, will initiate a skewed differentiation towards adipogenesis. BM MSCs were analysed with respect to lipid accumulation, gene expression, and adipokine production. In general, our hypothesis was not confirmed. No lipid accumulations were detected in the cells. In analysis of gene expression of the adipogenic transcription factors PPARγ and C/EBPα, certain changes were seen; however, due to lack of biological replicates, no statistical analyses could be applied to the results. Lastly, the inflammation and adipogenesis associated cytokine IL-6 displayed a slight increase, whereas the cytokines IL-8 and TNF-α were undetectable.

Philadelphia (Ph) chromosome, as a result of reciprocal translocation, is in majority of cases connected to two types of leukaemia - chronic myelogenous (CML) and acute lymphoblastic (ALL). The translocation occurs within large intronic sequences of BCR and ABL genes. The breakpoints are specific for individual patient and may be used as a target for monitoring of leukemic burden (MRD, minimal residual disease) during the treatment. In general, MRD is an important prognostic factor, which influences the treatment intensity. Two standardized methods are currently used for its monitoring. The first one is based on the detection of clonal specific Immunoglobulin and/or T-cell receptor genes rearrangements (and thus cannot be used for CML cases) at the DNA level, the second one utilizes detection of the BCR/ABL fusion gene at the mRNA level. Our aim was to optimize and standardize the process to find individual patient breakpoints on Ph chromosome and to use it for MRD quantification. We found the breakpoint in 80 % cases. The MRD data from 15 patients obtained by our method were compared to the levels obtained by standard methods (Ig/TCR and BCR/ABL transcript quantification). In all but 1 patient we found significant discrepancies, raising the questions about leukemic origin and the most accurate method for...

[Truncated abstract] The treatment of childhood acute lymphoblastic leukaemia (ALL) is one of the great success stories of paediatric oncology, transforming a universally fatal disease into one where 75 to 90% of children are now cured. Although in the past survival for children with T-cell ALL (T-ALL) lagged behind that of children with pre-B ALL, the use of contemporary intensified treatment strategies has significantly diminished this difference, with many investigators reporting similar cure rates for both groups of patients. Despite these marked improvements, numerous challenges still face physicians treating children with T-ALL. Firstly, there have been no additional major improvements in outcome over the last decade, despite additional treatment intensification. Secondly, effective regimens remain elusive for treating children with relapsed T-ALL or patients with resistant disease. Finally, there is a need to identify patients currently potentially overtreated and thus unnecessarily subjected to acute and long term toxicities without benefit. A major challenge therefore, is the identification of novel reliable prognostic markers, in order to identify patients at high risk of relapse and conversely those least likely to relapse, to guide therapy appropriately. Children predicted with a high risk of relapse would be candidates for intensification of therapy and/or novel experimental agents. Conversely, patients predicted to be at low risk of relapse could be offered clinical trials using reduced intensity therapy, thereby minimising toxicity. '...' Crucially, the 3-gene predictor was validated in a completely independent cohort of T-ALL patients, also treated on CCG style therapy. Our 3-gene predictor appears to identify a high risk group of patients which require alternative therapeutic strategies in order to attain a cure. This study has also identified a potential novel agent for the treatment of T-ALL, which may be used as an anthracycline potentiator or anthracycline-sparing agent. We hypothesised that genes associated with a relapse signature provide promising targets for novel therapies. We tested the hypothesis that CFLAR, an inhibitor of the extrinsic apoptotic pathway and a member of the 3-gene predictor may be involved in the development of resistance to chemotherapy. To test our hypothesis we used a novel agent, 2-cyano-3, 12-dioxooleana-1,9 (11)-dien-28-oic acid (CDDO), previously shown to inhibit CFLAR protein, in two cell lines established in our laboratory from paediatric patients diagnosed with T-ALL. We found that CDDO displayed single agent activity at sub-micromolar concentrations in both cell lines tested. Importantly, minimally lethal doses of CDDO resulted in significant enhancement of doxorubicin mediated cytotoxicity in one of the cell lines assessed. The findings presented as part of this thesis have revealed the value of gene expression analysis of childhood T-ALL for identifying novel prognostic markers. This study has shown that expression profiles may provide better prognostic information than currently available clinical variables. Additionally, genes that constitute a relapse signature may provide rational targets for novel therapies, as demonstrated in this study, which assessed a potential novel agent for the treatment of T-ALL.

We report a murine model, R26-βcat, expressing a stable form of β-catenin in T cells. R26-βcat pre-leukemic mice show a developmental block in T-cell differentiation and exhibit increased resistance to apoptosis. Interestingly, the mice develop T cell lymphomas independent of the Notch pathway. Furthermore, we showed that loss of the tumour suppressor Pten and over-expression of Myc was favoured; and may constitute the secondary events contributing to this leukemogenesis. We also demonstrated that R26-βcat tumours are malignant, heterogeneous and that leukaemia stem cells (LSC) were enriched in DP cells. Furthermore, the self-renewal capapcity of R26-βcat LSCs can to be exhausted.We propose that the R26-βcat model defines a new sub-group of Notch-independent T-ALL and the β-catenin may serve as a potential therapeutic target for these tumours.

Les leucémies aiguës (LA) sont un groupe hétérogène d'hémopathies malignes dues à latransformation oncogénique clonale des cellules souches hématopoïétiques (CSH). On distingue les LA myéloblastiques etlymphoblastiques (LAL). Les LAL sont classées selon le type de précurseur lymphoïde atteint, leur degré de maturité et leurs anomalies cytogénétiques.Le traitement permettant d'obtenir 80 à 90 % de rémission complète (RC) comporte une chimiothérapie d'induction, une consolidation et une intensification(intensification retardée ou allogreffe de CSH selon la situation pronostique). Néanmoins la survie globale à long terme n'est que de 40 à 50 %, du fait de la survenue de rechutes et de la toxicité des traitements. Différents groupes pronostiques basés sur la cytogénétique et la biologie moléculaire se dégagent,pouvant bénéficier de thérapeutiques adaptées. Dans les LAL à chromosome philadelphie (LAL à Ph),antérieurement de mauvais pronostic, les inhibiteurs de tyrosine kinase (ITK) permettent d'obtenir 80% de RCavec cependant un taux de rechute non négligeable. Nous avons démontré qu'une intensification thérapeutique par autogreffe chez des patients avec une maladie résiduelle indétectable permettait une survie à long terme prolongée avec une toxicité moindre que celle de l'allogreffe. En montrant l'implication de l'autotaxine dans les mécanismes de résistance aux ITK dans les LAL à Ph, nous ouvrons la voie à l'utilisation potentielle de nouvelles thérapeutiques. Dans les LAL T, groupe considéré de bon pronostic, un tiers des patients rechute. Nous avons démontré que l'absence de mutation de Notch et/ou FBXW7 ou la présence de mutations de RAS ou PTEN était de mauvais pronostic identifiant un sous-groupe de LAL T dont le traitement devait être renforcé. Nos travaux ont ainsi contribué à l'identification des groupes pronostiques dans les LAL et à l'adaptation des traitements afin d'améliorer les chances de survie. / Acute leukemias are a heterogeneous groups of malignant hematological diseases due to the clonaloncogenic transformation of hematopoietic stem cells(HSTs). We distinguish acute myeloblastic leukaemiafrom acute lymphoblastic leukemia (ALL). ALLs are classified according to the type of lymphoid precursoraffected, its degree of maturity, and with associated cytogenetic abnormalities.Treatment incorporating induction therapy,consolidation, and intensification – delayedintensification or allogeneic stem cell transplantation(SCT) according to prognostic factors – enable 80 to 90% of complete remission (CR). Nevertheless, long-termoverall survival is only 40 to 50% because of relapseand treatment-related toxicity. Different prognosticgroups based on cytogenetic abnormalities andmolecular biology are emerging and patients from eachprognostic group can benefit from adapted therapies.In chromosome Philadelphia-positive ALL (Ph+ ALL) which used to be of particular bad prognosis, tyrosinekinase inhibitors (TKIs) enables 80% of CR but with ahigh-relapse risk. We demonstrated that high-dosetherapy followed by autologous SCT enables prolongedlong-term survival with less drug-related toxicity ascompared to allogeneic SCT in patients with undetectable minimal residual disease. By showing the implication of autotaxine in the resistance to TKIs inPh+ LAL, we enable the use of novel therapeutics inclinical practice.T-cell ALL is considered of poor prognosis as one thirdof patients relapse. In this group of patients we showedthat the absence of a Notch and/or a FBXW7 mutation or the presence of mutations in RAS or PTEN identified a subgroup of patients in whom the treatmentmust be intensified. Our research has contributed to the identification of prognostic groups in ALL and to theadjustment of treatment according to potential survival.

Das in der vorliegenden Arbeit vorgestellte Verfahren der nicht-radioaktiven Southern Blot Hybridisierung unter Verwendung einer Digoxigenin Markierung hat sich für die Darstellung von Rekombinationen im TEL-Genlokus genomischer DNA als sensitive Vergleichsmethode bewiesen. Es wurden insgesamt 122 Kinder mit dieser Methode auf das Vorliegen der Translokation t(12;21) untersucht. Bei einer nur relevante Faktoren berücksichtigenden Beschränkung des PatientInnenkollektivs auf protokollgerecht nach ALL-REZ BFM behandelte B-Vorläufer-Zell-ALL und Erstrezidive konnte eine Rekombination von TEL in 5 von 65 PatientInnen (7,7%) nachgewiesen werden. Lässt man die Einschlusskriterien der ALL-REZ BFM Studie unberücksichtigt, handelt es sich sogar um 7 von 71 (9,9%) PatientInnen. Damit bestätigen die hier vorliegenden Ergebnisse den Trend der aktuellen Diskussion über die Häufigkeit des Vorliegens des Fusionsgenes TEL-AML1 bei Erstrezidiven, die eine kumulative Inzidenz bei einem 10-jährigen Untersuchungszeitraum von 9 ± 5% angeben. Weiterhin konnte mit ereignisfreien Beobachtungszeiträumen nach dem 1. Rezidiv im Median von 8,6 Jahren ein Trend zu späten Rezidiven und somit eine mittelfristig günstige Prognose für die TEL-Rearrangement positiven Rezidivfälle konstatiert werden. Zusammenfassend kann gesagt werden, dass TEL-AML1 positive PatientInnen eine Subgruppe darstellen, die lange erkrankungsfreie Intervalle mit zur Zeit üblichen Therapieprotokollen erreichen, nach Therapie der Ersterkrankung aber auch nach dem ersten Rezidiv. Auf Grund der sich aus dem retrospektiven PatientInnekollektiv ergebenen Selektion war es nicht möglich, statistisch signifikante Aussagen zur unabhängigen prognostischen Bedeutung für die langfristige Prognose von ALL im Kindesalter mit TEL-Rekombinationen zu treffen. / The presence of TEL/AML1 fusion gene in childhood acute lymphoblastic leukaemia (ALL) defines a subgroup of patients with better than average outcome. Around 20% of the patient at point of initial ALL diagnosis are characterised by this fusion transcript from translocation t(12;21)(p12;q22). However, the prognostic significance of this aberration has recently been disputed by the Berlin-Frankfurt-Munster (BFM) study group due to its relatively high incidence found in relapsed patients (19.6% and 21.9%, in two cohorts). Here we wanted to get more data in a long term follow up retrospect investigation by analysing DNA from frozen conserved bone marrow samples of 65 children. In the study presented here only five out of 65 (7.7%) patients selected as childhood B cell precursor acute lymphoblastic leukaemia only treated according to Berlin-Frankfurt-Munster (BFM) ALL relapse trial protocols (ALL-REZ BFM 82-96) (excluding T-lineage and Philadelphia chromosome (Ph)-positive leukaemia) carry this fusion. The detection was done due to a new developed non-radioactive Southern blotting with a Digoxigenin marked template. We could confirm the still good middle term prognosis in the relapsed TEL-AML1 positive subgroup. The TEL-AML1-positive and negative patients differed with respect to duration of last remission and age at initial diagnosis. At a median follow-up time of 8.6 years, children positive for TEL-AML1 had a higher probability of disease-free survival. Because of the small number of patients in this study it was not possible to get statistical significant facts about the independent prognostic impact for the long term prognosis of ALL in childhood with TEL rearrangement.

Increasing time trends in the recorded incidence of childhood cancer have been reported in many different settings. The extent to which these trends reflect real changes in incidence, rather than improvements in methods for diagnosis and registration, is controversial. Using data from the National Registry of Childhood Tumours (NRCT), this thesis investigates time trends in cancer diagnosed under age 15 in residents of Britain during 1966-2005 (54650 cases), and considers potential sources of artefact in detail. Several different methods are used to estimate completeness of NRCT registration. The history of methods for diagnosis and registration of childhood cancers in Britain is described, and predictions are made for effects on recorded incidence. For each of the 12 main diagnostic groups, Poisson regression is used to fit continuous time trends and ‘step’ models to the annual age-sex-standardised rates by year of birth and year of diagnosis. Age-specific rates by period, and quinquennial standardised rates for diagnostic subgroups, are shown graphically. For three broad groups (leukaemia, CNS tumours and other cancer), geographical variation is compared by period of diagnosis. The results of these analyses are discussed in relation to the predicted artefacts. The evidence for a positive association between affluence and recorded incidence of childhood leukaemia is briefly reviewed. A special form of diagnostic artefact, the ‘fatal infection’ hypothesis, is proposed as an explanation of both this association and the leukaemia time trend. This hypothesis is examined in a novel test based on clinical data. The recorded incidence of childhood cancer in Britain increased in each of 12 diagnostic groups during 1966-2005 (from 0.5% per year for bone cancer to 2.5% for hepatic cancer, with 0.7% for leukaemia). Evidence presented here suggests that these increases are probably artefacts of diagnosis and registration. The potential implications for epidemiological studies of childhood cancer should be considered.