Retrospektive Untersuchung des gemischten Chimerismus der Megakaryopoese im Rahmen der chronisch myeloischen Leukämie vor und nach allogener gegengeschlechtlicher Knochenmarktransplantation

La programmation des maladies non transmissibles est désormais un paradigme établi. Les événements indésirables encourus au cours de la vie foetale peuvent affecter le développement du foetus et sa santé future. Ce risque de pathologies à l'âge adulte est majoré lorsqu'il est associé à un environnement défavorable. Plusieurs arguments scientifiques viennent étayer le rôle des contaminants alimentaires dans les processus de la programmation développementale. Parmi ces contaminants, aucune mention n'est faite aux produits de la glycation issus des traitements thermiques des aliments et dont l'implication dans les désordres métaboliques et rénaux et dans le vieillissement est largement connue. Afin de vérifier leur implication dans la programmation du stress oxydant et de l'inflammation, nous avons administré à des porcs RCIU deux formules laitières. Une formule fortement chauffée à 120°C pendant 10 minutes (HHF) et une formule faiblement chauffée à 37°C pendant 5 minutes (LHF).Nous avons montré que la consommation de la formule HHF induit: 1) l'augmentation de la CML libre dans le sang des porcelets nourris avec ce régime ; 2) la présence d'un marquage de la CML dans les noyaux des cellules épithéliales rénales. Cette présence a également été observée dans les reins des animaux nourris avec le régime LHF mais pas chez les porcs allaités ; 3) une activation du récepteur soluble RAGE et l'augmentation de l'expression de gènes du système rénine-angiotensine, de l'inflammation, de l'apoptose ainsi que de l'oxydation des protéines dans le rein et dans le foie ; 4) des modifications importantes dans l'expression et le niveau d'activité de certaines enzymes antioxydantes dans le foie et le rein. Ces effets à long terme de la consommation postnatale de la formule HHF témoignent incontestablement d'un phénomène de programmation du système oxydant et de l'inflammation. Au niveau du colon, la formule HHF a contribué à l'augmentation transitoire des Bifidobactéries et des bactéries lactiques et à l'activation d'enzymes antioxydantes, démontrant le rôle joué par le microbiote intestinal dans la défense contre la présence des AGEs alimentaires pro-oxydants. Des études impliquant le MG dans les processus de programmation foetale ont été initiées sur le modèle rongeur. Elles montrent que le MG module la sécrétion d'insuline pancréatique de la descendance à l'âge adulte. Au regard de ces résultats, ce travail apporte des preuves nouvelles sur l'implication des AGEs alimentaires dans les processus de programmation développementale et souligne l'importance du contrôle de la présence de ces composés dans l'alimentation de la mère et de l'enfant / Programming of non-communicable diseases is now a well-established paradigm. Adverse events occurring during fetal life can affect fetal development and future health. This risk of disease in adulthood is increased in unfavorable environments. Several scientific studies support the role of dietary contaminants in developmental programming. Among these contaminants, no mention is made of glycation end products generated by heat treatment, which are largely implicated in metabolic disorders, kidney disorders and aging. In order to test their possible involvement in the programming of oxidative stress and inflammation, we administered two dairy formulas to IUGR pigs. First, a formula heated at 120 °C for 10 minutes (High Heated Formula: HHF), followed by a formula heated at 37 °C for 5 minutes (Low Heated Formula: LHF). We showed that the consumption of HHF formula did the following: 1) induced an increase in the level of free CML in the blood of IUGR animals during artificial suckling. 2) Resulted in the labelling of CML in the nuclei of renal epithelial cells. This labelling has also been detected in kidneys of animals fed with the LHF formula, but not in the kidneys of natural suckling piglets. 3) Activation of the soluble RAGE receptor, an increase in gene expression of the renin-angiotensin system, and an increase in inflammation, apoptosis and protein oxidation in the kidney and liver. 4) Significant changes in the expression and activity levels of certain antioxidant enzymes in the liver and kidney. These long-term effects of postnatal consumption of HHF formula undoubtedly demonstrate a programming phenomenon of oxidative stress and inflammation. In the colon, the HHF formula contributed to the transient increase in Bifidobacteria and Lactobacilli, and the activation of antioxidant enzymes, demonstrating the role of the gut microbiota in the defense against the presence of dietary pro-oxidant AGEs. Studies involving the ethyglyoxal the fetal programming process were initiated in the rodent model. They show that the MG modulates the secretion of pancreatic insulin by progeny during adulthood. In view of these results, this work provides new evidence for the involvement of dietary AGEs in the developmental programming process, and underlines the importance of controlling the presence of these compounds in the diet of both the mother and child

The COP9 signalosome (CSN) contains eight-subunits and is a highly conserved protein complex implicated in ubiquitin-mediated proteolysis. Jun activation domain-binding protein 1 (Jab1) is the fifth component of CSN (CSN5) with a molecular weight of 38 kDa. Jab1 overexpression is observed in many human cancers, but there is no clear evidence how Jab1 contributes to malignant transformation in human cancers. Bcr-Abl is a cytoplasmic chimeric oncoprotein produced by Philadelphia chromosome translocation and found in more than 90% of patients with chronic myelogenous leukemia (CML). Recent studies have shown that the Jab1/COP9 signalosome subcomplex is a downstream mediator of Bcr-Abl kinase and may facilitate cell-cycle progression. In this study, we found that inhibition of Bcr-Abl kinase by STI-571 downregulated 50% of full length human Jab1 promoter activity and gene expression. Promoter deletion assay indicated that the responsive element for Bcr-Abl is located between -405/-223 region of human Jab1 promoter. Treatment of LY294002 also reduced Jab-405/-223 promoter activity and Jab1 expression. Promoter mutagenesis assay and ChIP assay suggest that Bcr-Abl stimulated both £]-catenin /TCF complex and STAT1 bind to the consensus binding sites of Jab-405/-223 promoter. Taken together, Bcr-Abl oncogene may regulate Jab1 via PI3K/AKT signal pathway, £]-catenin /TCF and STAT1 transcription factors.

Ability to diagnose cancer before it progresses into advanced stages is highly desirable for the best treatment outcome. A sensitive test to analyze complex samples for specific cancer biomarkers would provide with important prognostic information and help to select the best treatment regimen. A highly robust, ultra sensitive and cost-effective electronic chip platform was used to detect nucleic acid biomarkers in heterogeneous biological samples without any amplification or purification. Chronic myelogenous leukemia (CML) was chosen as a model disease due to its hallmark genetic abnormality. This disease state therefore has an ideal market to test the detection of the fusion transcripts in complex samples, such as blood. It was shown that the CML-related fusion can be detected from unpurified cell lysates and as low as 10 cells were needed for detection. Finally, patient samples were analyzed using the assay and the fusion transcripts were accurately identified in all of them.

Ability to diagnose cancer before it progresses into advanced stages is highly desirable for the best treatment outcome. A sensitive test to analyze complex samples for specific cancer biomarkers would provide with important prognostic information and help to select the best treatment regimen. A highly robust, ultra sensitive and cost-effective electronic chip platform was used to detect nucleic acid biomarkers in heterogeneous biological samples without any amplification or purification. Chronic myelogenous leukemia (CML) was chosen as a model disease due to its hallmark genetic abnormality. This disease state therefore has an ideal market to test the detection of the fusion transcripts in complex samples, such as blood. It was shown that the CML-related fusion can be detected from unpurified cell lysates and as low as 10 cells were needed for detection. Finally, patient samples were analyzed using the assay and the fusion transcripts were accurately identified in all of them.

Die vorliegende Arbeit handelt von einer in vitro Untersuchung der Stoffwechselveränderun-gen durch die Expression von BCR/ABL bei BaF3-Zellen, einer murinen, IL-3-abhängigen B-Zelllinie. Die Zellen wurden in nährstoffreichem Standard- und in durch Titrationen ermittel-tem nährstoffarmem Minimalmedium auf unterschiedliche Stoffwechselaktivität in Abhän-gigkeit von BCR/ABL-Expression untersucht sowie auf die zusätzliche Beeinflussbarkeit durch IL-3. Danach wurden vergleichend zwischen den 2 Zelllinien (BaF3 und BaF3-BCR/ABL) im Minimalmedium und im Standardmedium Metabolite wie Glukose, Laktat und Aminosäuren bestimmt, wobei BaF3-BCR/ABL sowohl mit als auch ohne IL-3 kultiviert wur-de. Um den Einfluss von Nährstoffrestriktion auf die Therapie zu zeigen, wurden anschlie-ßend vergleichend in den beiden Medien die Tyrosinkinaseinhibitoren Imatinib und Nilotinib titriert. Die Ergebnisse zeigen, dass BaF3-BCR/ABL einen Wachstumsvorteil im Minimalmedium hat, welcher im Standardmedium nicht vorliegt. Während die bereits bekannte Verstärkung der Glukoseaufnahme durch BCR/ABL im Standardmedium bestätigt wurde, konnte im Minimal-medium Gegenteiliges gezeigt werden. Zudem wurde ein Unterschied im Aminosäurestoff-wechsel zwischen BaF3 + IL-3 und BaF3-BCR/ABL + IL-3 im Minimalmedium deutlich. Die therapeutische Relevanz des gezeigten Einflusses der Nährstoffrestriktion konnte anschlie-ßend in der Tyrosinkinaseinhibitortitration dargestellt werden, da die Medikamente in Abhän-gigkeit vom Medium unterschiedliche Wirkungen zeigen. Insgesamt bieten die Ergebnisse einen metabolischen Erklärungsansatz für das Überleben von Tumorstammzellen in nährstoffarmen Arealen des Knochenmarks unter Therapie und Raum für neue Therapieansätze.

The Snedden lab has been studying a family of Ca2+-binding proteins from Arabidopsis that are related to the prototypical Ca2+ sensor calmodulin (CaM) and are termed CMLs (CaM-like proteins). Previous work on CML42 demonstrated that it displays biochemical properties typical of Ca2+ sensors and interacts in vitro with KIC (KCBP-interacting Ca2+-binding protein), a protein known to function in trichome branching. In the present study, I investigated whether CML42 is also involved in trichome branching. I examined a CML42 T-DNA insertion knockout line (cml42) and found that it exhibits a mutant trichome phenotype with increased branch numbers compared to wildtype plants. All other aspects of cml42 growth and morphology, including root hairs, appeared normal relative to wildtype plants. kic knockout plants did not show any discernible trichome phenotype when compared to wildtype plants, nor did transgenic lines overexpressing CML42. Transgenic plants lacking both CML42 and KIC expression (cml42kic) displayed a cml42 mutant phenotype. The genetic studies suggest that CML42 is a negative regulator of trichome branching. Biochemical analysis on recombinant full-length CML42, C-terminal, and N-terminal fragments, using the fluorescent probe 8-Anilino-1-naphthalenesulfonate (ANS), demonstrated that Ca2+-binding results in a conformational change in CML42 and the exposure of hydrophobic regions, particularly within the C-terminal lobe. Collectively, data from the Snedden Lab support the important role of Ca2+ signalling in trichome branching and morphology. / Thesis (Master, Biology) -- Queen's University, 2009-08-11 14:00:06.008

Part I BCR-ABL fusion oncogene results fromt(9;22)(q34;q11) translocation of chromosome is the most common genetic abnormality found in chronic myeloid leukemia (CML) cells . The encoded protein of this fusion gene exhibits constitutively active tyrosinekinase activity which is required for the pathogenesis of CML. We addressed how BCR-ABL oncoprotein increased Skp2 expression. Treatment of Imatinib or LY294002 reduced Skp2mRNA in BCR-ABL-positive K562 cells. Knockdown of AKT by small hairpin RNAalso reduced Skp2 expression. We found that BCR-ABL up-regulated Skp2 via Sp1 because (1) the Sp1 site located at the −386/−380 promoter region was important for BCR-ABL-induced Skp2 promoter activity, (2) chromatin immunoprecipitation assay demonstrated that Imatinib inhibited the recruitment of p300 to the Sp1 site of Skp2 promoter and (3) knockdown of Sp1 reduced Skp2 expression in K562 cells. These results suggest that BCR-ABL controls Skp2 gene transcription via the PI3K/AKT/Sp1 pathway. In addition to transcriptional regulation of Skp2, Bcr-Abl also modulates Skp2 protein stability in these cells. Treatment of Bcr-Abl kinase inhibitor imatinib led to G1 growth arrest accompanied with reduced Skp2 expression. Interestingly, reduction of Skp2 protein occurred prior to down-regulation of Skp2 mRNA suggesting a post-translational control. The half-life of Skp2 protein was significantly attenuated in imatinib-treated cells. Knockdown of Bcr-Abl similarly caused Skp2 protein instability. The decrease of Skp2 was induced by increased protein degradation through the ubiquitin/ proteasome pathway. Our results demonstrated that imatinib treatment or Bcr-Abl knockdown reduced Emi1, an endogenous inhibitor of the E3 ligase APC/Cdh1 which mediated the degradation of Skp2 protein. We found that Emi1 stability was regulated by phosphorylation and mutation of tyrosine 142 significantly reduced the stability. Lines of evidence suggested Bcr-Abl-induced Emi1 phosphorylation was mediated by Src kinase. (1) Src inhibitor SU6656 inhibited Emi1 tyrosine phosphorylation in Bcr-Abl-positive K562 cells. (2) Transfection of v-Src rescued the reduction of Emi1 by imatinib. (3) Mutation of tyrosine 142 to phenylalanine (Y142F) abolished the phosphorylation of Emi1 by recombinant Src kinase. In addition, ectopic expression of wild type but not Y142F mutant Emi1 could counteract imatinib-caused G1 growth arrest. Collectively, our results suggest that Bcr-Abl fusion oncogene increases Emi1 phosphorylation and stability to prevent Skp2 protein degradation via APC/Cdh1-induced ubiquitination and to enhance proliferation of CML cells. Part II Although imatinib therapy of chronic myelogenous leukemia is effective, the resistance to imatinib challenges the treatment of this disease. Therefore, search of novel drugs to overcome imatinib resistance is a critical issue in clinic. Withaferin A (WA), an extract of Withania somniferia, exhibits anti-cancer activity on a number of solid tumors. In this study, we investigate the effect of WA on imatinib-sensitive and -resistant CML cells. WA at low concentrations induced autophagy in imatinib-sensitive K562 cells. Co-treatment of chloroquine suppressed autophagy and switched WA-treated K562 cells to apoptosis. This data indicated that autophagy protected K562 cells from apoptosis induced by WA. However, we found that WA triggered caspase activation and apoptosis in imatinib-resistant T315I-positive cells and this effect was associated with down-regulation of Akt activity. Treatment of the AKT inhibitor LY294002 also caused apoptosis in imatinib-resistant T315I-positive cells. Ectopic expression of constitutively active Akt reversed WA-induced apoptosis and caspase activation in imatinib-resistant T315I-positive cells. Molecular study demonstrates that WA repressed the Akt signaling pathway by decreasing Akt expression. We found that WA abolished formation of the hsp90/cdc37/Akt complex to cause Akt degradation through the ubiquitin- and proteasome-dependent pathway. More importantly, WA also induced AKT down-regulation and apoptosis in primary CML cells. Taken together, our results suggested that imatinib-resistant T315I-positive cells were more addicted to Akt-dependent survival pathway and were more sensitive to WA. Therefore, WA could be useful for the treatment of imatinib-resistant CML. Part III Suberoylanilide hydroxamic acid (SAHA) is undergoing clinical trial for the treatment of various cancers including chronic myeloid leukemia (CML). We study the potential miRNAs which involved in the anti-cancer effect of SAHA. Microarray analysis revealed that the expression of 57 and 63 miRNAs was significantly changed in K562 cells treated with SAHA for 8h and 24h respectively. Five miRNAs(miR-92a, miR-199b-5p, miR-223, miR-627 and miR-675) were highly expressed in K562 cells and continuously repressed by SAHA. miR-92a and miR-223 known to play important roles in normal and hematopoisis were further characterized. Up-regulation of miR-92a was found in K562 cells and in primary CML cells. Inhibition of miR-92a with SAHA led to increase of the tumor suppressor Fbxw7. Conversely, ectopic expression of pri-miR-92a reversed SAHA-induced apoptosis of K562 cells, increase of Fbxw7 3¡¦-UTR reporter activity and up-regulation of Fbxw7. Collecively, miR-92a is up-regulated in CML cells, and SAHA downregulated the expression of miR-92a to result in apoptosis of CML cells.

The natural history of CML has been transformed in recent years by the introduction of Glivec[superscript TM] (imatinib mesylate), an ABL kinase inhibitor, which provides the new treatment paradigm for chronic phase CML. While the majority of patients with CP-CML respond very well to imatinib, there are approximately 15% of patients who fail to respond, or respond suboptimally. While the major cause of secondary imatinib resistance can be attributable to kinase domain mutations, the underlying cause of primary resistance is yet to be elucidated. Utilizing the phosphorylation of the adaptor protein Crkl, an immediate downstream partner of BCRABL, as a surrogate measure of BCR-ABL kinase activity, a large interpatient variation in the degree of imatinib induced kinase inhibition achieved in-vitro, was observed in previously untreated CP-CML patients. The observed in-vitro sensitivity was a good predictor of molecular response in patients treated with 600mg imatinib as front line therapy. Furthermore, analysis of the in-vivo reduction in p-Crkl mediated measured in blood cells in response to imatinib over the first 28 days of therapy, revealed that patients with higher % reductions respond significantly better over a two year period, than those with lower % reductions. Using 14-C labelled imatinib, it was demonstrated that this intrinsic sensitivity correlated to the amount of drug which was retained within the target haemopoietic cell, and furthermore, that a critical determinant of the active influx of imatinib, was the functional activity of the human organic cation transporter -1 (OCT-1), as determined by a prazosin (potent inhibitor of OCT-1) inhibition assay. Patients with high OCT-1 Activity had superior molecular responses when compared to those with low OCT-1 Activity, but in those patients who could tolerate increased imatinib dose, these inferior responses could be largely overcome. In contrast, Nilotinib, a more potent second generation tyrosine kinase inhibitor, is not dependent on OCT-1 for influx, making it a possible treatment choice for patients with low OCT-1 Activity. Both imatinib and nilotinib interact with the efflux transporters ABCB1, and ABCG2. In combination studies imatinib results in a significantly increased intracellular concentration of nilotinib, most likely through interaction with these efflux transporters. Furthermore, commonly used therapies such as proton pump inhibitors also interact with ABCB1 and ABCG2, and demonstrable changes in intracellular drug concentrations were observed in-vitro with concomitant administration of these agents and imatinib or nilotinib at clinically relevant concentrations. In conclusion, these data demonstrate that the degree of kinase inhibition mediated in-vitro and in-vivo by imatinib, is a critical determinant of subsequent molecular response. This intrinsic sensitivity to imatinib induced kinase inhibition is related to the activity of the OCT-1 protein. This protein is not involved in the transport of nilotinib, suggesting it as a possible treatment alternative in those patients with low OCT-1 Activity. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1319077 / Thesis (Ph.D.) -- University of Adelaide, School of Medicine, 2008

La leucémie myéloïde chronique (LMC) est un syndrome myéloprolifératif clonal initié par l’activité tyrosine kinase de l’oncoprotéine de fusion BCR-ABL dans une cellule souche hématopoïétique (CSH) très primitive et caractérisée par une instabilité génétique responsable de l’évolution clonale de la maladie. Les mécanismes de survie, d’autorenouvellement et ceux de la progression vers une phase de leucémie aigüe sont difficilement modélisables dans les CSH primaires de patients. La technologie des IPSC ; permettant de reprogrammer les cellules leucémiques à un état pluripotent ; pourrait permettre de générer in vitro des progéniteurs et des cellules leucémiques très primitives, dont l’évolution biologique pourrait être séquentiellement analysée. Dans ce but, nous avons généré une lignée IPSC à partir des cellules leucémiques d’un patient atteint de LMC. Nous avons montré que la lignée IPSC différenciée en hémangioblastes ou en progéniteurs hématopoïétiques présente un potentiel clonogénique accru. Ce potentiel est modulable sous l’action de l’imatinib mesylate ; qui inhibe l’autophosphorylation de BCR-ABL et celle de la protéine CRK-L ; mais également par la manipulation pharmacologique de la voie AHR impliquée dans la quiescence des CSH. En utilisant une stratégie de mutagénèse in vitro, nous avons montré la possibilté d’exacerber le potentiel hématopoietique des cellules hématopoïétiques dérivées des iPSC leucémiques. Les iPSC analysées après traitement par l’agent mutagène ENU présentent des anomalies cytologiques et cytogénétiques additionnelles reminiscentes de la phase blastiques de la maladie. Les analyses moléculaires par aCGH ont permis d’identifier dans les cellules hématopoïétiques dérivées d’IPSC traités par ENU, une signature moléculaire compatible avec celle décrite dans les cellules blastiques de patients. L’ensemble de nos résultats suggèrent qu’il est possible de modéliser certains aspects de la LMC ; notamment un phénotype myéloprolifératif ; et de génerer un modèle de progression blastique in vitro à partir des iPSC leucémiques, permettant ainsi d’identifier de nouveaux biomarquers prédictifs de progression tumorale ou le criblage de médicaments. / Chronic myeloid leukemia (CML) is a clonal myeloproliferative malignancy initiated by tyrosine kinase activity of the fusion oncoprotein BCR-ABL in very primitive hematopoietic stem cell and characterized by a genetic instability leading to clonal progression. Mechanisms of survival, self-renewal and progression of the disease are difficult to model using primary leukemic cells. The use of iPSC technology could allow reprogramming of leukemic cells to pluripotency with generation of primitive leukemic cells whose evolution can be sequentially analyzed. For this purpose, we generated an IPSC cell line from the leukemic cells of a CML patient and analyzed the possibility to generate a myeloproliferative phenotype. We have shown that this iPSC exhibits an increased hematopoietic potential either via EB or Blast-CFC generation. This potential can be modulated by the action of imatinib, inhibiting autophosphorylation of BCR-ABL and that of CRKL. We show that hematopoietic potential of CML iPSC can also be modulated by using AHR antagonists, which allow further amplification of hematopoietic cells. To evaluate the possibility of generating a clonal progression model in vitro, we have used a mutagenesis strategy. CML iPSC treated by ENU for several weeks generated hematopoietic cells with increased efficiency. These cells showed evidence of cytological and cytogenetic abnormalities reminiscent of a blast crisis. aCGH analyses of hematopoietic cells generated revealed genomic abnormalities described in CML blast crisis and a molecular signature compatible with blast crisis described in CML patients. These results suggest the feasibility of using patient specific iPSC for modeling CML blast crisis, which could be used for discovery of novel biomarkers and drug screening.