Reproduction de : Thèse doctorat : Pharmacie. Biochimie et biologie moléculaire : Reims : 2004. / Bibliogr.

Chronic myeloid leukemia (CML) is characterized by clonal expansion of hematopoietic progenitor cells, result from the translocation (9:22). The oncogene BCR-ABL, in the Ph chromosome, is transcribed and translated into a fusion protein BCR / ABL. The ABL tyrosine kinase (TK) in the fusion protein is constitutively activated and is needed for the initial leukemogenic event of CML and its activity induces production of reactive oxygen species (ROS). Of particular relevance to CML is the fact that an increase of ROS can have consequences, facilitating genomic instability may contribute to disease progression. The aim of this study was to determine the oxidative status in patients with CML, in attendance at a university hospital (HUWC). This is a cross-sectional study consisted of 30 adult patients of both sexes with clinical and laboratory diagnosis of CML on treatment with inhibitors (TK) 1st and 2nd generation. The concentrations of malondialdehyde (MDA) and nitrite (NO2-) were performed by spectrophotometric method. The activities of enzymes glutathione peroxidase (GSH-Px) and catalase (CAT) were determined in hemolysate by Glutathione Peroxidase Cellular Activity Kit  Assay (Sigma-Aldrich) and spectrophotometry, respectively. Total glutathione, reduced glutathione (reduced GSH), glutathione (GSSG) were determined by Total Glutathione Activity Kit  (Assay Designs, Inc) and calculated the ratio GSH / GSSG. For statistical analysis of nonparametric data was used  and ANOVA test for multiple comparisons Tukey. It was considered the minimum level of significance of 5%. The average concentrations of NO2- and MDA were increased in CML patients compared to control, regardless of disease activity. The antioxidant profile was characterized by decreased CAT and GSH-Px increased also independent of disease activity. The reduced GSH is presented decreased, the GSSH, increased and GSH / GSSG decreased. It was observed that patients using protease inhibitors of TK 2nd generation of oxidative stress parameters were significantly elevated compared to controls. In the analysis of patients on imatinib were not detected significant changes in oxidative status. We conclude that patients with CML are under oxidative stress and impaired antioxidant activity. / A Leucemia mielÃide crÃnica (LMC) à caracterizada pela expansÃo clonal de cÃlulas progenitoras hematopoÃticas, resultante da translocaÃÃo (9:22). O oncogene de fusÃo BCR-ABL, no cromossomo Ph, à transcrito e traduzido numa proteÃna de fusÃo BCR/ABL. A tirosina quinase (TK) ABL na proteÃna de fusÃo à constitutivamente ativada sendo necessÃria para os eventos leucemogÃnicos iniciais da LMC e sua atividade induz a produÃÃo de espÃcies reativas de oxigÃnio (EROs). De particular relevÃncia para LMC à o fato de que um aumento de EROs pode ter consequÃncias, facilitando a instabilidade genÃmica podendo contribuir para a progressÃo da doenÃa. O objetivo do estudo foi determinar o perfil oxidativo em pacientes com LMC, em acompanhamento ambulatorial no Hospital UniversitÃrio Walter CantÃdio (HUWC). Trata-se de um estudo transversal constituÃdo de 30 pacientes adultos, com diagnostico clÃnico e laboratorial de LMC, em tratamento com inibidores de (TK) de 1 e 2 geraÃÃo. As concentraÃÃes de malonaldeÃdo (MDA) e de nitrito (NO2-) foram realizadas por mÃtodo espectofotomÃtrico. As atividades das enzimas Glutationa peroxidase (GSH-Px) e catalase (CAT) foram determinadas no hemolisado, por kit Glutathione Peroxidase Cellular Activity Assay (Sigma-Aldrich) e por espectofotometria, respectivamente. Glutationa total, glutationa reduzida (GSH reduzida), glutationa oxidada (GSSG) foram determinadas por kit Total Glutathione Activity (Assay Designs, Inc) e calculada a relaÃÃo GSH/GSSG. Para a anÃlise estatÃstica de dados nÃo paramÃtricos foi utilizado o ANOVA e o teste de mÃltiplas comparaÃÃes de Tukey. Foi considerado o nÃvel mÃnimo de significÃncia de 5%. As concentraÃÃes mÃdia de MDA e de NO2- foram aumentadas nos pacientes com LMC em relaÃÃo ao controle, independente da atividade da doenÃa. O perfil antioxidante foi caracterizado pela diminuiÃÃo da CAT e aumento da GSH-Px tambÃm independente da atividade da doenÃa. A GSH reduzida se apresentou diminuÃda, a GSSH, aumentada e a relaÃÃo GSH/GSSG diminuÃda. Os pacientes em uso de inibidores de TK de 2 geraÃÃo apresentaram parÃmetros do estresse oxidativo significativamente elevados em relaÃÃo ao grupo controle. Conclui-se que os pacientes com LMC estÃo sob estresse oxidativo e com atividade antioxidante comprometida.

Inhibiting BCR-ABL kinase activity with tyrosine kinase inhibitors (TKIs) has been the frontline therapy for CML. Resistance to TKIs frequently occurs, but the mechanisms remain elusive. First, to uncover survival pathways involved in TKI resistance in CML, I conducted a genome-wide RNAi screen in human CML cells to identify genes governing cellular sensitivity to the first generation TKI called IM (Gleevec). I identified genes converging on and activating the MEK/ERK pathway through transcriptional up-regulation of PRKCH. Combining IM with a MEK inhibitor synergistically kills TKI-resistant CML cells and CML stem cells. Next, I performed single cell RNA-seq to compare expression profiles of CML stem cells and hematopoietic stem cells isolated from the same patient. Among the genes that are preferentially expressed in CML stem cells is PIM2, which encodes a pro-survival serine-threonine kinase that phosphorylates and inhibits the pro-apoptotic protein BAD. Inhibiting PIM2 function sensitizes CML stem cells to IM-induced apoptosis and prevents disease relapse in a CML mouse model. Last, I devised a CRISPR-Cas9 based strategy to perform insertional mutagenesis at a defined genomic location in murine hematopoietic Ba/F3 cells. As proof of principle, we showed its capability to perform unbiased, saturated point mutagenesis in a 9 amino acid region of BCR-ABL encompassing the socalled “gatekeeper” residue, an important determinant of TKI binding. We found that the ranking order of mutations from the screen correlated well with their prevalence in IM-resistant CML patients. Overall, my findings reveal novel resistance mechanisms in CML and provide alternative therapeutic strategies.

Th.--Méd.--Nancy 1, 1984. N°: 161.

Chronic myeloid leukemia (CML) is a disease characterized by the expansion of granulocytic cells. The BCR-ABL tyrosine kinase inhibitor imatinib, the frontline treatment for Ph+ leukemias, can induce complete hematologic and cytogenetic response in most chronic phase CML patients. Despite the remarkable initial clinic effects, it is now recognized that imatinib will unlikely cure patients because a small cell population containing leukemic stem cells (LSCs) with self-renewal capacity is insensitive to tyrosine kinase inhibitors. In Chapter I, I briefly review the BCR-ABL kinase and its related signaling pathways. BCR-ABL kinase activates several signaling pathways including MAPK, STAT, and JNK/SAPK. BCR-ABL also mediates kinase-independent pathways through SRC family kinases. I will also discuss pathways involving β-catenin, hedgehog, FoxO and Alox5 are critical to the regulation of self-renewal and differentiation in LSC of CML. As detailed in Chapter II, I describe our work evaluating the effects of omacetaxine, a novel CML drug inducing cell apoptosis by inhibition of protein synthesis, on self-renewal and differentiation of LSCs and BCR-ABL-induced CML and acute lymphoblastic leukemia (B-ALL) in mice. We found that treatment with omacetaxine decreased the number of LSCs and prolonged the survival of mice with CML or B-ALL. In chapter III, I describe that Alox5 is an essential gene in the function of LSCs and CML development. We show evidence that Alox5 affects differentiation, cell division, and survival of long-term LSCs. Treatment of CML mice with a 5-LO inhibitor also impaired the function of LSCs similarly and prolonged survival. In chapter IV, I present evidence of our work showing a further dissection the Alox5 pathway by comparing the gene expression profiles of wild type and Alox5-/- LSCs. We show that Msr1 deletion causes acceleration of CML development. We also show that Msr1 affects CML development by regulating the PI3K-AKT pathway and β-catenin. Taken together, these results demonstrate that some pathways including Alox5 and Msr1 play an important role in regulating the self-renewal and differentiation of LSC. More efforts should be put into developing the novel strategies that may effectively target LSCs and thus cure CML.

Dissertation (Ph.D.)--University of South Florida, 2009. / Includes vita. Includes bibliographical references. Also available online.

Dissertation (Ph.D.)--University of South Florida, 2009. / Title from PDF of title page. Document formatted into pages; contains 149 pages. Includes vita. Includes bibliographical references.

Chronic myeloid leukemia (CML) is a clonal hematopoietic stem cell disorder associated with the Philadelphia chromosome (Ph) that arises from a reciprocal translocation between chromosomes 9 and 22, thereby resulting in the formation of the chimeric BCR-ABL oncogene encoding a constitutively activated tyrosine kinase. BCR-ABL tyrosine kinase inhibitors (TKIs) induce a complete hematologic and cytogenetic response in the majority of chronic phrase CML patients. However, TKIs cannot efficiently eradicate leukemia stem cells (LSCs) because of the insensitivity of LSCs to TKIs. Therefore, developing new strategies to target LSCs is necessary and critical for curing CML, and success of this approach depends on further understanding the molecular mechanisms by which LSCs survive and are maintained. In Chapter I, I briefly introduce CML disease, BCR-ABL oncoprotein, and TKIs. I also describe the identification and features of LSCs. Several key pathways in LSCs including Wnt/ß-catenin, hedgehog, FoxO, Bcl6 and HIF1, are discussed. I also propose our strategy to identify unique molecular pathways that are important for LSCs but not their normal stem cell counterparts. In Chapter II, I describe our finding about the function of the positive regulator, HIF1α, in CML development and LSC survival. I show that loss of HIF1α impairs the maintenance of CML through impairing cell cycle progression and inducing apoptosis of LSCs, and I also report that p16Ink4a and p19Arf mediate the effect of HIF1α on LSCs, as knockdown of p16Ink4a and p19Arf rescues the defective colony-forming ability of HIF1α-/- LSCs. As detailed in Chapter III and IV, through comparing the global gene expression profiles of LSCs and HSCs, I find two novel regulators, Blk and Scd1, which act as tumor suppressors in CML development. In Chapter III, I show that Blk is markedly down-regulated by BCR-ABL in LSCs, and that c-Myc and Pax5 mediate this down-regulation. Deletion of Blk accelerates CML development; conversely, Blk overexpression significantly delays the development of CML and impairs the function of LSCs. I also demonstrate that p27, as a downstream effector, is involved in the function of Blk in LSCs. Blk also functions as a tumor suppressor in human CML stem cells, and inhibits the colony-forming ability of human CML cells. In Chapter IV, I investigate the function of another negative regulator, Scd1, in CML LSCs, and find that expression of Scd1 is down-regulated in mouse LSCs and human CML cells. We report that Scd1 acts as a tumor suppressor in CML, as loss of Scd1 causes acceleration of CML development and overexpression of Scd1 delays CML development. Using a colony-forming assay, I demonstrate that Scd1 impairs the maintenance of LSCs due to the change of expression of Pten, p53 and Bcl2. Importantly, I find that both Blk and Scd1 do not affect normal hematopoietic stem cells (HSCs) or hematopoiesis. Taken together, our findings demonstrate that HIF1α is required for the maintenance of CML LSCs, and conversely that Blk and Scd1 suppress the function of LSCs, suggesting that combining TKI treatment with specific targeting of LSCs will be necessary for curing CML.

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No. of bitstreams: 2 Tese - Adriana do Prado Barbosa - 2015.pdf: 900945 bytes, checksum: c7a5ed7dcaeb54e2967829169a9de269 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-04-10 / Fundação de Amparo à Pesquisa do Estado de Goiás - FAPEG / The treatment of chronic myeloid leukemia (CML) has changed dramatically with the advent of imatinib mesylate (IM). Besides the convenience of oral use, other benefits were achieved with the new drug, with faster therapeutic responses and increased survival, giving the CML similar characteristics as chronic diseases. In this scenario, there was another challenge, drug compliance, since a significant proportion of patients fail to ingest all the prescribed doses of imatinib. The concern was to optimize the adherence of CML patients, the hematology ambulatory at the Clinical Hospital of the Federal University of Goias (HC-UFG), led the authoress to create a film cartoon, as a pro-adhesion educational intervention model. To investigate the effectiveness of this new educational material, we used in 65 patients three adherence measures, two indirect (Morisky Test and Molecular Response [MR]) and direct (plasma dosage of IM), before and after the screening of film. In univariate analysis, from the Morisky Test, the film was striking, with increased adherent patients, which increased from 15 (23.1%) to 43 (66.1%). The results of MR showed an improvement trend after the movie, because the positive molecular response (major MR or complete MR) increased from 81.5% to 86.1%. Regarding the serum levels of IM, with daily doses of 400-800 mg IM, the premovie samples showed higher average than the post-movie (2473.16 ± 1049.55 ng/ml versus 1414.72 ± 715 73 ng/ml), with a variation coefficients interpatients of 43.4% and 50.6%, respectively. This high dispersion index found has been reported by other authors. By multivariate analysis, patients were divided into three groups. The first brought together compliant patients before and after the film with a good therapeutic response (major MR) after the intervention. It was: patients over 53 years old, females, with associated diseases before and after the treatment of CML that use more than two drugs in addition to imatinib. The second group was marked by the change of not adherence pre to adherence post-film. Its features were younger than or equal to 53, the absence of other disease before the CML, the use of less than two drugs and complete molecular response after the film. In the third group, we observed patients without molecular response before and after the educational intervention and no medication adherence after the film. They had in common their age (less than or equal to 53 years), and drug discontinuation due to adverse reactions. The last represents the set of patients resistant to the educational film, drawing attention to the fact that only one pro-adhesion method may be insufficient for all individuals. It is concluded that medication adherence was higher among patients older than 53 years, the educational film is an effective proadhesion assistance and continuing education, if combined with another method, it could help maintain or enhance the benefits achieved in this work. / O tratamento da leucemia mielóide crônica (LMC) mudou radicalmente com o advento do mesilato de imatinibe (MI). Além da comodidade do uso oral, outros benefícios foram alcançados com o novo fármaco, como respostas terapêuticas mais rápidas e aumento da sobrevida, dando `a LMC características semelhantes `as de doenças crônicas. Neste cenário, surgiu outro desafio, a adesão medicamentosa, pois uma proporção significativa de pacientes deixa de ingerir a dose prescrita de imatinibe. A preocupação em otimizar a adesão dos pacientes com LMC, do Ambulatório de Hematologia do Hospital das Clínicas da Universidade Federal de Goiás (HC-UFG), motivou a autora a criar um filme em desenho animado, como modelo de intervenção educativa pró-adesão. Para investigar a eficácia deste novo material educativo, empregou-se, em 65 pacientes, três medidas de adesão, duas indiretas (Teste de Morisky e Resposta Molecular [RM]) e uma direta (dosagem plasmática do MI), antes e depois da exibição do filme. Em análise univariada, pelo teste de Morisky, o filme foi impactante, com aumento dos pacientes aderentes, que passaram de 15 (23,1%) para 43 (66,1%). Os resultados da RM indicaram uma tendência de melhora após o filme, pois a resposta molecular positiva (RM maior ou RM completa) passou de 81,5% para 86,1%. Em relação `a dosagem sérica do MI, com doses diárias entre 400-800 mg de MI, as amostras pré-filme apresentaram média superior `as do pósfilme (2.473,16 ± 1.049,55 ng/ml versus 1.414,72 ± 715,73 ng/ml), com coeficientes de variação interpaciente de 43,4% e 50,6%, respectivamente. Este elevado índice de dispersão encontrado tem sido relatado por outros autores. Pela análise multivariada, os pacientes foram separados em três grupos. O primeiro, reuniu os pacientes aderentes antes e após o filme e com boa resposta terapêutica (RM maior) após a intervenção. Foram eles: os doentes com mais de 53 anos, do gênero feminino, com doenças associadas antes e após o tratamento da LMC e que usam mais de dois medicamentos além do imatinibe. O segundo grupo foi marcado pela mudança de não adesão pré para adesão pós-filme. Suas características foram idade menor ou igual a 53, ausência de outra doença antes da LMC, uso de menos de dois medicamentos e resposta molecular completa pós-filme. No terceiro grupo, observou-se pacientes sem resposta molecular antes e depois da intervenção educativa, bem como não adesão medicamentosa após o filme. Eles tinham em comum a idade, menor ou igual a 53 anos, e suspensão do medicamento por reação adversa. Estes últimos representam o conjunto de pacientes resistentes ao filme educacional, chamando atenção para o fato de que somente um método pró-adesão pode ser insuficiente para todos os indivíduos. Conclui-se que a adesão medicamentosa foi maior entre os pacientes maiores de 53 anos, que o filme educativo é uma intervenção pró-adesão eficaz e que a educação continuada, aliada a outro método, poderia ajudar a manter ou ampliar os benefícios conquistados neste trabalho.

The human Philadelphia chromosome (Ph) arises from a translocation between chromosomes 9 and 22 [t(9;22)(q34;q11)]. The resulting chimeric BCR-ABLoncogene encodes a constitutively activated, oncogenic tyrosine kinase that induces chronic myeloid leukemia (CML) and B-cell acute lymphoblastic leukemia (B-ALL). The BCR-ABL tyrosine kinase inhibitor (TKI), imatinib mesylate, induces a complete hematologic and cytogenetic response in the majority of CML patients, but is unable to completely eradicate BCR-ABL–expressing leukemic cells, suggesting that leukemia stem cells are not eliminated. Over time, patients frequently become drug resistant and develop progressive disease despite continued treatment. Two major reasons cause the imatinib resistance. The first one is the BCR-ABL kinase domain mutations which inhibit the interaction of BCR-ABL kinase domain with imatinib; the second one is the residual leukemia stem cells (LSCs) in the patients who are administrated with imatinib. To overcome these two major obstacles in CML treatment, new strategies need further investigation. As detailed in Chapter II, we evaluated the therapeutic effect of Hsp90 inhibition by using a novel water-soluble Hsp90 inhibitor, IPI-504, in our BCR-ABL retroviral transplantation mouse model. We found that BCR-ABL mutants relied more on the HSP90 function than WT BCR-ABL in CML. More interestingly, inhibition of HSP90 in CML leukemia stem cells with IPI-504 significantly decreases the survival and proliferation of CML leukemia stem cells in vitro and in vivo. Consistent with these findings, IPI-504 treatment achieved significant prolonged survival of CML and B-ALL mice. IPI-504 represents a novel therapeutic approach whereby inhibition of Hsp90 in CML patients and Ph+ ALL may significantly advance efforts to develop a cure for these diseases. The rationale underlying the use of IPI-504 for kinase inhibitor–resistant CML has implications for other cancers that display oncogene addiction to kinases that are Hsp90 client proteins. Although we proved that inhibition of Hsp90 could restrain LSCs in vitro and in vivo, it is still unclear how to define specific targets in LSCs and eradicate LSCs. In Chapter III, we took advantage of our CML mouse model and compared the global gene expression signature between normal HSCs and LSCs to identify the downregulation of Pten in CML LSCs. CML develops faster when Pten is deleted in Ptenfl/fl mice. On the other hand, Pten overexpression significantly delays the CML development and impairs leukemia stem cell function. mTOR is a major downstream of Pten-Akt pathway and it is always activated or overepxressed when Pten is mutated or deleted in human cancers. In our study, we found that inhibition of mTOR by rapamycin inhibited proliferation and induced apoptosis of LSCs. Notably, our study also confirmed a recent clinical report that Pten has been downregulated in human CML patient LSCs. In summary, our results proved the tumor suppressor role of Pten in CML mouse model. Although the mechanisms of Pten in leukemia stem cells still need further study, Pten and its downstream, such as Akt and mTOR, should be more attractive in LSCs study.