No description available.

No description available.

Acute myeloid leukemia (AML) is a deadly cancer of the blood and bone marrow defined by the accumulation of immature and non-functional myeloid progenitor cells. While AML is associated with a high success of chemotherapy-induced remission, it is accompanied by high relapse rates with poor response to subsequent therapies. Therefore, relapsed AML patients only have a 10% probability of long-term survival. An effective postinduction therapy is allogeneic hematopoietic stem cell transplantation (HSCT). However, complications associated with HSCT can be more severe than the AML disease itself. To date, no robust methodology is available to prospectively identify and distinguish AML patients that are more likely to benefit from HSCT. Our group has shown that AML patients with high leukemic progenitor cell content (LPC+) have a significantly lower overall survival (OS) when compared to patients with lower LPC content (LPC-). The objective of this study was to determine whether the LPC assay can be used as a functional predictor of post-HSCT survival. We hypothesized that LPC content correlates to post-HSCT survival times. We performed LPC assays on over 100 primary AML patient samples, showing that HSCT significantly improved OS in both LPC+ and LPC- patients, but LPC+ patients benefited more strongly than LPC- patients. This provides an initial basis to suggest that HSCT can offset the negative prognostic impact associated with high LPC content. To understand the biology of LPCs, we employed the Infinium HumanMethylation450 BeadChip assay to determine whether there are any methylation patterns that distinguish LPC+ and LPC- patients. However, we were not able to discover any uniquely methylated regions that separate the two groups, suggesting for further studies with an increased patient cohort, or extending the analyses to the transcript level. Given the rarity of curative approaches to cancers, a prognostic measure that could determine whether any single patient will benefit from HSCT will have an immediate impact. / Thesis / Master of Science (MSc)

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 111-122).

Thesis (Ph. D.)--University of Washington, 1996. / Vita. Includes bibliographical references (leaves [154]-166).

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Orientador: Patricia da Silva Melo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Aplicadas / Made available in DSpace on 2018-08-27T21:30:15Z (GMT). No. of bitstreams: 1 Ferreira_IasminRosanneSilva_M.pdf: 836058 bytes, checksum: 5beb54192fc88a1ebf1ce80d1b2424bd (MD5) Previous issue date: 2014 / Resumo: Compostos encontrados na natureza, mostram uma enorme gama de diversidade em termos de estrutura e atividades farmacológicas. Apesar dos avanços na sintese química, as plantas se mostram cada vez mais eficientes na busca de novos tratamentos contra o câncer. Assim, o objetivo deste estudo foi avaliar seis fitoterápicos pertencentes à classe de lignoides (dimethoxymagnolol, grandisina e iangambina) e riparinas (I, II e III) , com e sem suplementação de glutationa (GSH - 1mM) em três linhagens de células leucêmicas K562, U937 e HL60. A viabilidade celular foi avaliada por ensaio de redução de MTT em células leucemicas tratadas com os fitoquímicos (com ou sem suplementação de GSH). Nas células U937 foram encontrados valores de IC50 de 100 ?M, 30 ?M e 500 ?M em células tratadas com dimethoximagnolol, grandisina e iangambina, respectivamente, e 60, 25 e 15 ?M (riparina I, II e III, respectivamente). Nas células K562, o tratamento com riparinas foi o mais eficaz dos compostos estudados , uma vez que foram determinados valores de IC50 de 125, 27 e 15 ?M ( riparina I, II e III, respectivamente). Diferentes valores foram encontrados em células HL60 tratadas com riparinas (140, 100 e 75 ?M para riparina I, II e III, respectivamente). A suplementação com GSH amenizou apenas os efeitos tóxicos após tratamento das células U937 com riparina II, uma vez que não foram observados resultados diferentes em outras linhagens celulares tratadas com os compostos estudados com a suplementação de GSH. A citotoxicidade desses fitoquímicos também foi avaliada em linhagem de células de fibroblasto de pulmão permanente (V79), que são células de cultura utilizadas para os estudos de citotoxicidade. Todos os fitoquímicos investigados, com exceção da iangambina, foram menos tóxicos para células V79 do que para as células leucêmicas. Estes resultados se mostram positivos, uma vez que a atividade farmacológica foi maior nas células leucêmicas do que nas células V79. Todos os compostos estudados neste trabalho apresentaram efeitos anti-tumorais, no entanto, o mecanismo de ação da riparina II é diferente em células U937 já que a suplementação com GSH foi eficaz contra os efeitos tóxicos. Provavelmente, a riparina II provocou a morte celular por estresse oxidativo / Abstract: Compounds found in nature, show an enormous range of diversity in terms of structure and pharmacologic activities. Plants play a surprisingly important source of new treatments for cancer, despite advances in chemical synthesis. Thus the aim of this study was to evaluate six phytomedicine belonging to the class of lignoid (dimethoxymagnolol, grandisin and yangambin) and riparins (I, II and III) with and without glutathione supplementation (GSH ¿ 1mM) in three leukemic lines, K562, U937 and HL60. The cell viability was evaluated by MTT reduction assay in leukemic cells treated with the phytochemicals (with or without GSH supplementation). In the U937 cell IC50 values found were 100 µM, 30 µM and 500 µM in the cells treated with dimethoximagnolol, grandisin and yangambin, respectively and 60, 25 and 15 µM (riparin I, II and III, respectively). In K562 cells the treatment with riparins were the most effective class of compounds studied since it was determined IC50 values of 125, 27 and 15µM (riparin I, II and III, respectively). Different values were determined in the HL60 cells treated with riparins (140, 100 and 75 ?M for riparin I, II and III, respectively). GSH ameliorated only the toxic effects evaluated in U937 cell treated with riparin II, since it was not observed different results in the others cell lines treated with the studied compounds plus GSH. The cytotoxicity of phytochemicals was also assessed in a permanent lung fibroblast cell line (V79) culture that are cells commonly used for cytotoxicity studies. All the phytochemicals investigated, with the yangambin exception, were less cytotoxic to V79 cells than to leukemic cells. These results indicate a positive pharmacologic application since the leukemic activity was major than to the toxic effects evaluated in the V79 cells. All the compounds investigated in this work has antitumoral effects, however the action mechanism of riparin II is different on U937 cell since GSH supplementation protected the toxic effects. Probably, riparin II triggered cell death by stress oxidative pathway / Mestrado / Metabolismo e Biologia Molecular / Mestra em Ciências da Nutrição e do Esporte e Metabolismo

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Le métabolisme oxydatif joue un rôle important dans l’hématopoïèse normale et leucémique. L’homéostasie des espèces réactives de l’oxygène (ROS) est un élément crucial qui repose sur une balance finement régulée entre leur élimination et leur production. A ce niveau, des études ont montrés une différence entre cellules souches leucémique (CSL) présentant un faible niveau de ROS et cellules différenciées leucoblastiques présentant un plus fort niveau de ROS. Dans cette étude nous avons montré que les NADPH oxydases sont des producteurs majeurs de ROS des cellules de leucémies aiguës myéloïdes. Les cellules leucoblastiques, quelque soit le stade de différenciation présentent une activité NADPH oxydase constitutive qui contribue à leur niveau de ROS élevé et favorise leur prolifération en accélérant le cycle cellulaire. A l’inverse, les analyses réalisées sur des CSL grâce à des modèles murins de leucémies primaires induites par les oncogènes Hoxa9 et Meis1 suggèrent qu’il existerait une plus faible activité oxydase dans les cellules souches leucémiques. / Oxydative metabolism play a key role in normal and leukemic hematopoiesis. Reactive oxygen species (ROS) homeostasis is a crucial point which is the result of a finely regulated balance between elimination and production. Recent studies establishe a difference in ROS level between leukemic stem cells (LSC, ROSlow) and differentiated leucoblasts (higher level). In our study we have shown that NADPH oxidases are major ROS producers in acute myeloid leukemic cells. Leukoblasts, wathever their differentition stage, have a constitutive NADPH oxydase activity that contributes to the ROS level and promotes the proliferation by accelerating the cell cycle. Conversly, the analyses of LSCs performed by using murins primary leukemia induced by Hoxa9 and Meis1 oncogens suggest a potential lower NADPH oxidase activity in LSCs.

The CBFbeta-SMMHC fusion protein is expressed in acute myeloid leukemia (AML) samples with the chromosome inversion inv(16)(p13;q22). This fusion protein binds the transcription factor RUNX with higher affinity than its physiological partner CBFbeta and disrupts the core binding factor (CBF) activity in hematopoietic stem and progenitor cells. Studies in the Castilla laboratory have shown that CBFbeta-SMMHC expression blocks differentiation of hematopoietic progenitors, creating a pre-leukemic progenitor that progresses to AML in cooperation with other mutations. However, the combined function of cumulative cooperating mutations in the pre-leukemic progenitor cells that enhance their expansion to induce leukemia is not known. The standard treatment for inv(16) AML is based on the use of non-selective cytotoxic chemotherapy, resulting in a good initial response, but with limited long-term survival. Therefore, there is a need for developing targeted therapies with improved efficacy in leukemic cells and minimal toxicity for normal cells. Here, we used conditional Nras+/LSL-G12D; Cbfb+/56M; Mx1Cre knock-in mice to show that allelic expression of oncogenic N-RasG12D expanded the multi-potential progenitor (MPP) compartment by 8 fold. Allelic expression of Cbfbeta-SMMHC increased the MPPs and short-term hematopoietic stem cells (ST-HSCs) by 2 to 4 fold both alone and in combination with N-RasG12D expression. In addition, allelic expression of oncogenic N-RasG12D and Cbfbeta-SMMHC increases survival of pre-leukemic stem and progenitor cells. Differential analysis of bone marrow cells determined that Cbfb+/MYH11 and Nras+/G12D; vii Cbfb+/MYH11 cells included increased number of blasts, myeloblasts and promyelocytes and a reduction in immature granulocytes, suggesting that expression of N-RasG12D cannot bypass Cbfbeta-SMMHC driven differentiation block. N-RasG12D and Cbfbeta-SMMHC synergized in leukemia, in which Nras+/G12D; Cbfb+/MYH11 mice have a shorter median latency than Cbfb+/MYH11 mice. In addition, the synergy in leukemogenesis was cell autonomous. Notably, leukemic cells expressing N-RasG12D and Cbfbeta-SMMHC showed higher (over 100 fold) leukemia-initiating cell activity in vivo than leukemic cells expressing Cbfbeta-SMMHC (L-IC activity of 1/4,000 and 1/528,334, respectively). Short term culture and biochemical assays revealed that pre-leukemic and leukemic cells expressing N-RasG12D and Cbfbeta-SMMHC have reduced levels of pro-apoptotic protein Bim compared to control. The Nras+/G12D; CbfbMYH11 pre-leukemic and leukemic cells were sensitive to pharmacologic inhibition of MEK/ERK signaling pathway with increasing apoptosis and Bim protein levels but not sensitive to PI3K inhibitors. In addition, knock-down of Bcl2l11 (Bim) expression in Cbfbeta-SMMHC pre-leukemic progenitors decreased their apoptosis levels. In collaboration with Dr. John Bushweller’s and other research laboratories, we recently developed a CBFbeta-SMMHC inhibitor named AI-10-49, which specifically binds to CBFbeta-SMMHC, prevents its binding to RUNX proteins and restores CBF function. Biochemical analysis in human leukemic cells showed that AI-10-49 has significant specificity in reducing the viability of leukemic cells expressing CBFbeta-SMMHC (IC50= 0.83μM), and negligible toxicity in normal cells. Likewise, mouse Nras+/G12D; viii Cbfb+/MYH11 leukemic cells were sensitive to AI-10-49 (IC50= 0.93μM). By using the NrasLSL-G12D; Cbfb56M mouse model, we also show that AI-10-49 significantly prolongs the survival of mice bearing the leukemic cells. Preliminary mechanistic analysis of AI-10-49 activity has shown that AI-10-49 increased BCL2L11 transcript levels in a dose and time dependent manner in murine and human leukemic cells, suggesting that the viability through BIM-mediated apoptosis may be targeted by both oncogenic signals. My thesis study demonstrates that Cbfbeta-SMMHC and N-RasG12D promote the survival of pre-leukemic myeloid progenitors primed for leukemia by activation of the MEK/ERK/Bim axis, and define NrasLSL-G12D; Cbfb56M mice as a valuable genetic model for the study of inv(16) AML targeted therapies. For instance, the novel CBFbeta-SMMHC inhibitor AI-10-49 shows a significant efficacy in this mouse model. This small molecule will serve as a promising first generation drug for targeted therapy of inv(16) leukemia and also a very useful tool to understand mechanisms of leukemogenesis driving by CBFbeta-SMMHC.