AML is a cancer of the blood and bone marrow characterized by the presence of highly proliferative and abnormally differentiated myeloblasts. Previous work from the Bhatia lab utilized the orthotopic xenograft model in order to isolate a population of leukemic regenerating cells (LRC) that exists prior to relapse. Affymatrix analysis of LRCs revealed up-regulation of 248 genes that can act as unique targets to prevent relapse. In order to screen compounds against all 248 targets, it is important to develop an in vitro model that is able to appropriately recapture the functional and molecular markers of LRCs. Primary AML samples were treated with 5-doses of 0.15 μM, 1 μM AraC, or DMSO control and several outcomes were measured. In vitro AraC treatment was not able to recapitulate the progenitor frequency curve and CD34 expression curve observed in vivo. Additionally, we were not able to see a consistent increase in select LRC targets DRD2, GLUT2, FUT3, and FASL via flow cytometry. Despite an increase in the mRNA levels of LRC genes 24h after treatment with 0.15 μM AraC, long term analysis could not be completed due to poor RNA quality and low expression of LRC-targets. Primary AML cells were co-culture with mouse MS-5 stromal cell line order to study the effects of mesenchymal stromal cells on AML response to AraC. Co-culture with MS-5 cells had different effects on select primary AML cells. AML 14939 showed an increase in CD34 and LRC targets DRD2 and FUT3 following AraC treatment when co-cultured with MS-5 cells; while A374 showed no differences between DMSO and AraC treated groups. Overall, these findings suggest the LRC signature is not induced by treatment with AraC alone. Complex interactions between AML cells and their bone marrow niche during AraC treatment plays an important role in the development of LRCs prior to AML relapse. / Thesis / Master of Science (MSc) / AML is a cancer of blood cells characterized by the presence of rapidly dividing cancer cells termed myeloblasts. AML has a high rate of disease relapse. The Bhatia lab modelled AML relapse in a mouse and discovered an unique population of cells that exist prior to relapse termed LRCs. LRCs express distinctive genes that can act as targets for the development of new therapies to prevent relapse. In order to screen potential relapse preventing compounds, we set out to recapture AML relapse using cells in a dish. AML cells from patients were treated with chemotherapy reagent AraC and the number of cancer progenitors and the expression of specific LRC proteins were measured. AraC did not increase the level of 3 out of 4 LRC proteins studied. We determined the LRCs were not caused by AraC treatment, and the physiology of the bone marrow environment plays an important role in inducing relapse.

No description available.

Introdução: O Transplante Alogênico de Célula Tronco Hematopoiética (TCTH alogênico) é um procedimento de alto potencial curativo para a Leucemia Mielóide Aguda (LMA), principalmente pelo efeito “graft versus leukemia” (GVL), que leva a redução do risco de recaída. Atualmente, os pacientes com LMA de risco intermediário são submetidos ao procedimento caso possuam doador aparentado. Pacientes sem doador aparentado disponível são submetidos a tratamento de consolidação com quimioterapia, com maior chance de recaída da doença. Acredita-se que os pacientes submetidos ao TCTH tenham maiores sobrevida global e livre de doença, a despeito das altas taxas de morbimortalidade. A classificação de risco é extremamente importante para escolha terapêutica pós remissão. Assim, a realização da pesquisa de marcadores moleculares, para refinar a estratificação prognóstica, tem importância especial no grupo de risco intermediário, complementando a avaliação citogenética, e auxiliando na decisão terapêutica, sendo cada vez mais necessária, apesar de não disponível em todos os centros. Material e métodos: Foram avaliados os pacientes com LMA de risco intermediário em primeira Remissão Completa (1RC) do Serviço de Hematologia e TCTH do Hospital de Clínicas de Porto Alegre do período de 01 de abril de 1999 a 01 de outubro de 2014, com pelo menos 1 ano de seguimento após o tratamento, através de revisão de prontuários. Os dados foram dispostos no programa Excel e posteriormente exportados para o programa SPSS v. 18.0 para análise estatística. Resultados: Foram avaliados 69 pacientes, sendo 45 pacientes submetidos a consolidação com quimioterapia (“QT”) e 24 submetidos a TCTH Alogênico (“TCTH Alogênico”). A média de idade do grupo “QT” foi de 47,8 anos e do grupo “TCTH Alogênico” foi de 35,5 anos, com diferença estatisticamente significativa (P<0,001). Não houve diferença na distribuição entre o sexo. A mediana de tempo de seguimento do grupo “QT” foi de 1,1 anos (intervalo interquartil de 0,4 a 2,5 ) e no grupo “TCTH Alogênico” foi de 2,7 anos (intervalo interquartil de 0,4 a 5,5), sem diferença estatisticamente significativa na distribuição dos tempos de seguimento entre os grupos (P=0,236). A sobrevida do grupo “QT” em 12 meses foi de 52,3% e no grupo “TCTH Alogênico” foi de 62,5%. Aos 24 meses, a sobrevida do grupo “QT” foi de 31,7% e no grupo “TCTH Alogênico” foi de 58,3% e em 5 anos de 21,1% e 53,8%, respectivamente. O teste do Long-Rank aponta uma diferença estatisticamente significativa nas sobrevidas entre os grupos após 5 anos, com Hazard Ratio (HR) para óbito de 2,2 (IC 95%: 1,1-4,2), P=0,027, porém ao ajustarmos a relação pela idade esta associação perde significância estatística (HR:1,6 IC95%:1 - 1,1; P=0,246) Discussão: Os dados evidenciaram melhor sobrevida no grupo submetido à TCTH alogênico, porém o grupo submetido ao procedimento apresentava média de idade menor. No entanto, apesar da perda da significância estatística, o HR corrigido para idade permanece maior para o grupo sem TCTH, o que pode dever-se ao “n” pequeno da amostra. Identificar quais pacientes terão benefício com TCTH torna-se cada vez mais um desafio. O uso de marcadores moleculares são importantes no refinamento da estratificação de risco do grupo de risco intermediário, podendo auxiliar nessa decisão. Além disso, com o advento da possibilidade de condicionamentos não mieloablativos como alternativa aos pacientes mais velhos e com escore de comorbidades pior e a melhor terapia de suporte, talvez possamos ser menos conservadores na indicação desse procedimento, identificando assim aqueles que poderão obter melhores resultados no tratamento de uma doença tão agressiva e grave. / Background: Allogeneic Hematopoietic Stem Cell Transplantation (allo-HSCT) is a high potentially curative procedure to Acute Myeloid Leukemia (AML), mainly by the “graft-versus-leukemia” (GVL) effect, which leads to reduced risk of relapse. Nowadays, intermediate risk AML patients are submitted to this procedure if a matched sibling donor is available. Patients without a sibling donor are submitted to consolidation with chemotherapy, with a greater chance of relapse. It is believed that patients submitted to allo-HSCT have a greater overall survival and disease-free survival, even though it presents high morbidity and mortality rates. Risk stratification is extremely important to post-remission treatment choice. Molecular markers research is especially important in intermediate risk group, complementing cytogenetic evaluation to a better prognostic stratification and, although it is still not available in all health centers, it is more and more necessary. Materials and Methods: We evaluated intermediate risk AML patients in first Complete Remission (CR1) at the Hematology Service and Bone Marrow Transplantation from Hospital de Clínicas de Porto Alegre from April 1st 1999 to October 1st 2014, and which had, at least, a one year follow-up after treatment, by conducting a medical record review. Data was inserted in Microsoft Excel 2010 spreadsheets and after exported to SPSS v. 18.0 to statistical analysis. Results: Among the 69 patients analyzed, 45 were submitted to consolidation with chemotherapy (Intermediate risk AML – non allo-HSCT) and 24 of then submitted to allo-HSCT (Intermediate risk AML – allo-HSCT). The average age of Intermediate risk AML – non allo-HSCT was 47.8 years old and Intermediate risk AML – allo-HSCT was 35.5 years old, with statistically significance difference (P<0,001). There was no difference regard sex of patients. The median follow-up in the Intermediate risk AML – non allo-HSCT was 1.1 years (interquartile rage of 0.4 to 2.5) and in the Intermediate risk AML – allo-HSCT was 2.7 years (interquartile rage of 0.4 to 5.5), with no statistically significance difference in follow-up time distribution between groups (P=0.236). Intermediate risk AML – non allo-HSCT survival in 12 months was 52.3% and in the Intermediate risk AML – allo-HSCT was 62.5%. In 24 months, Intermediate risk AML – non allo-HSCT survival was 31.7% and in Intermediate risk AML – allo HSCT survival was 58.3% and in 5 years it was 21.1% and 53.8% respectively. Long- Rank test indicates a statistically significant difference in survival between groups after 5 years, with hazard ratio (HR) for death of 2.2 (IC95% 1.1 – 4.2), P=0.027, but when we adjust the relation to age, this association loses statistical significance (HR:1.6 95%CI: 1 – 1.1; P=0.246). Discussion: Data showed a better survival rate to the group submitted to allo-HSCT, but the group presented a lower average age. However, despite de loss of statistical significance, Hazard Ratio (HR), adjusted to age remains higher to the non allo-HSCT group. It can be explained by the small number of the sample. Identifying which patients will benefit from allo-HSCT becomes increasingly challenging. The use of molecular markers are important in the refinement of risk stratification in intermediate risk group, assisting in the decision. Moreover, with the advent of the possibility of nonmyeloablative conditioning as an alternative to older patients and with worst rates of comorbidity, and the better supporting therapy, we may be less conservative in indicating this procedure, identifying the patients who may obtain better results during treatment of such aggressive and serious disease.

Introdução: O Transplante Alogênico de Célula Tronco Hematopoiética (TCTH alogênico) é um procedimento de alto potencial curativo para a Leucemia Mielóide Aguda (LMA), principalmente pelo efeito “graft versus leukemia” (GVL), que leva a redução do risco de recaída. Atualmente, os pacientes com LMA de risco intermediário são submetidos ao procedimento caso possuam doador aparentado. Pacientes sem doador aparentado disponível são submetidos a tratamento de consolidação com quimioterapia, com maior chance de recaída da doença. Acredita-se que os pacientes submetidos ao TCTH tenham maiores sobrevida global e livre de doença, a despeito das altas taxas de morbimortalidade. A classificação de risco é extremamente importante para escolha terapêutica pós remissão. Assim, a realização da pesquisa de marcadores moleculares, para refinar a estratificação prognóstica, tem importância especial no grupo de risco intermediário, complementando a avaliação citogenética, e auxiliando na decisão terapêutica, sendo cada vez mais necessária, apesar de não disponível em todos os centros. Material e métodos: Foram avaliados os pacientes com LMA de risco intermediário em primeira Remissão Completa (1RC) do Serviço de Hematologia e TCTH do Hospital de Clínicas de Porto Alegre do período de 01 de abril de 1999 a 01 de outubro de 2014, com pelo menos 1 ano de seguimento após o tratamento, através de revisão de prontuários. Os dados foram dispostos no programa Excel e posteriormente exportados para o programa SPSS v. 18.0 para análise estatística. Resultados: Foram avaliados 69 pacientes, sendo 45 pacientes submetidos a consolidação com quimioterapia (“QT”) e 24 submetidos a TCTH Alogênico (“TCTH Alogênico”). A média de idade do grupo “QT” foi de 47,8 anos e do grupo “TCTH Alogênico” foi de 35,5 anos, com diferença estatisticamente significativa (P<0,001). Não houve diferença na distribuição entre o sexo. A mediana de tempo de seguimento do grupo “QT” foi de 1,1 anos (intervalo interquartil de 0,4 a 2,5 ) e no grupo “TCTH Alogênico” foi de 2,7 anos (intervalo interquartil de 0,4 a 5,5), sem diferença estatisticamente significativa na distribuição dos tempos de seguimento entre os grupos (P=0,236). A sobrevida do grupo “QT” em 12 meses foi de 52,3% e no grupo “TCTH Alogênico” foi de 62,5%. Aos 24 meses, a sobrevida do grupo “QT” foi de 31,7% e no grupo “TCTH Alogênico” foi de 58,3% e em 5 anos de 21,1% e 53,8%, respectivamente. O teste do Long-Rank aponta uma diferença estatisticamente significativa nas sobrevidas entre os grupos após 5 anos, com Hazard Ratio (HR) para óbito de 2,2 (IC 95%: 1,1-4,2), P=0,027, porém ao ajustarmos a relação pela idade esta associação perde significância estatística (HR:1,6 IC95%:1 - 1,1; P=0,246) Discussão: Os dados evidenciaram melhor sobrevida no grupo submetido à TCTH alogênico, porém o grupo submetido ao procedimento apresentava média de idade menor. No entanto, apesar da perda da significância estatística, o HR corrigido para idade permanece maior para o grupo sem TCTH, o que pode dever-se ao “n” pequeno da amostra. Identificar quais pacientes terão benefício com TCTH torna-se cada vez mais um desafio. O uso de marcadores moleculares são importantes no refinamento da estratificação de risco do grupo de risco intermediário, podendo auxiliar nessa decisão. Além disso, com o advento da possibilidade de condicionamentos não mieloablativos como alternativa aos pacientes mais velhos e com escore de comorbidades pior e a melhor terapia de suporte, talvez possamos ser menos conservadores na indicação desse procedimento, identificando assim aqueles que poderão obter melhores resultados no tratamento de uma doença tão agressiva e grave. / Background: Allogeneic Hematopoietic Stem Cell Transplantation (allo-HSCT) is a high potentially curative procedure to Acute Myeloid Leukemia (AML), mainly by the “graft-versus-leukemia” (GVL) effect, which leads to reduced risk of relapse. Nowadays, intermediate risk AML patients are submitted to this procedure if a matched sibling donor is available. Patients without a sibling donor are submitted to consolidation with chemotherapy, with a greater chance of relapse. It is believed that patients submitted to allo-HSCT have a greater overall survival and disease-free survival, even though it presents high morbidity and mortality rates. Risk stratification is extremely important to post-remission treatment choice. Molecular markers research is especially important in intermediate risk group, complementing cytogenetic evaluation to a better prognostic stratification and, although it is still not available in all health centers, it is more and more necessary. Materials and Methods: We evaluated intermediate risk AML patients in first Complete Remission (CR1) at the Hematology Service and Bone Marrow Transplantation from Hospital de Clínicas de Porto Alegre from April 1st 1999 to October 1st 2014, and which had, at least, a one year follow-up after treatment, by conducting a medical record review. Data was inserted in Microsoft Excel 2010 spreadsheets and after exported to SPSS v. 18.0 to statistical analysis. Results: Among the 69 patients analyzed, 45 were submitted to consolidation with chemotherapy (Intermediate risk AML – non allo-HSCT) and 24 of then submitted to allo-HSCT (Intermediate risk AML – allo-HSCT). The average age of Intermediate risk AML – non allo-HSCT was 47.8 years old and Intermediate risk AML – allo-HSCT was 35.5 years old, with statistically significance difference (P<0,001). There was no difference regard sex of patients. The median follow-up in the Intermediate risk AML – non allo-HSCT was 1.1 years (interquartile rage of 0.4 to 2.5) and in the Intermediate risk AML – allo-HSCT was 2.7 years (interquartile rage of 0.4 to 5.5), with no statistically significance difference in follow-up time distribution between groups (P=0.236). Intermediate risk AML – non allo-HSCT survival in 12 months was 52.3% and in the Intermediate risk AML – allo-HSCT was 62.5%. In 24 months, Intermediate risk AML – non allo-HSCT survival was 31.7% and in Intermediate risk AML – allo HSCT survival was 58.3% and in 5 years it was 21.1% and 53.8% respectively. Long- Rank test indicates a statistically significant difference in survival between groups after 5 years, with hazard ratio (HR) for death of 2.2 (IC95% 1.1 – 4.2), P=0.027, but when we adjust the relation to age, this association loses statistical significance (HR:1.6 95%CI: 1 – 1.1; P=0.246). Discussion: Data showed a better survival rate to the group submitted to allo-HSCT, but the group presented a lower average age. However, despite de loss of statistical significance, Hazard Ratio (HR), adjusted to age remains higher to the non allo-HSCT group. It can be explained by the small number of the sample. Identifying which patients will benefit from allo-HSCT becomes increasingly challenging. The use of molecular markers are important in the refinement of risk stratification in intermediate risk group, assisting in the decision. Moreover, with the advent of the possibility of nonmyeloablative conditioning as an alternative to older patients and with worst rates of comorbidity, and the better supporting therapy, we may be less conservative in indicating this procedure, identifying the patients who may obtain better results during treatment of such aggressive and serious disease.

Introdução: O Transplante Alogênico de Célula Tronco Hematopoiética (TCTH alogênico) é um procedimento de alto potencial curativo para a Leucemia Mielóide Aguda (LMA), principalmente pelo efeito “graft versus leukemia” (GVL), que leva a redução do risco de recaída. Atualmente, os pacientes com LMA de risco intermediário são submetidos ao procedimento caso possuam doador aparentado. Pacientes sem doador aparentado disponível são submetidos a tratamento de consolidação com quimioterapia, com maior chance de recaída da doença. Acredita-se que os pacientes submetidos ao TCTH tenham maiores sobrevida global e livre de doença, a despeito das altas taxas de morbimortalidade. A classificação de risco é extremamente importante para escolha terapêutica pós remissão. Assim, a realização da pesquisa de marcadores moleculares, para refinar a estratificação prognóstica, tem importância especial no grupo de risco intermediário, complementando a avaliação citogenética, e auxiliando na decisão terapêutica, sendo cada vez mais necessária, apesar de não disponível em todos os centros. Material e métodos: Foram avaliados os pacientes com LMA de risco intermediário em primeira Remissão Completa (1RC) do Serviço de Hematologia e TCTH do Hospital de Clínicas de Porto Alegre do período de 01 de abril de 1999 a 01 de outubro de 2014, com pelo menos 1 ano de seguimento após o tratamento, através de revisão de prontuários. Os dados foram dispostos no programa Excel e posteriormente exportados para o programa SPSS v. 18.0 para análise estatística. Resultados: Foram avaliados 69 pacientes, sendo 45 pacientes submetidos a consolidação com quimioterapia (“QT”) e 24 submetidos a TCTH Alogênico (“TCTH Alogênico”). A média de idade do grupo “QT” foi de 47,8 anos e do grupo “TCTH Alogênico” foi de 35,5 anos, com diferença estatisticamente significativa (P<0,001). Não houve diferença na distribuição entre o sexo. A mediana de tempo de seguimento do grupo “QT” foi de 1,1 anos (intervalo interquartil de 0,4 a 2,5 ) e no grupo “TCTH Alogênico” foi de 2,7 anos (intervalo interquartil de 0,4 a 5,5), sem diferença estatisticamente significativa na distribuição dos tempos de seguimento entre os grupos (P=0,236). A sobrevida do grupo “QT” em 12 meses foi de 52,3% e no grupo “TCTH Alogênico” foi de 62,5%. Aos 24 meses, a sobrevida do grupo “QT” foi de 31,7% e no grupo “TCTH Alogênico” foi de 58,3% e em 5 anos de 21,1% e 53,8%, respectivamente. O teste do Long-Rank aponta uma diferença estatisticamente significativa nas sobrevidas entre os grupos após 5 anos, com Hazard Ratio (HR) para óbito de 2,2 (IC 95%: 1,1-4,2), P=0,027, porém ao ajustarmos a relação pela idade esta associação perde significância estatística (HR:1,6 IC95%:1 - 1,1; P=0,246) Discussão: Os dados evidenciaram melhor sobrevida no grupo submetido à TCTH alogênico, porém o grupo submetido ao procedimento apresentava média de idade menor. No entanto, apesar da perda da significância estatística, o HR corrigido para idade permanece maior para o grupo sem TCTH, o que pode dever-se ao “n” pequeno da amostra. Identificar quais pacientes terão benefício com TCTH torna-se cada vez mais um desafio. O uso de marcadores moleculares são importantes no refinamento da estratificação de risco do grupo de risco intermediário, podendo auxiliar nessa decisão. Além disso, com o advento da possibilidade de condicionamentos não mieloablativos como alternativa aos pacientes mais velhos e com escore de comorbidades pior e a melhor terapia de suporte, talvez possamos ser menos conservadores na indicação desse procedimento, identificando assim aqueles que poderão obter melhores resultados no tratamento de uma doença tão agressiva e grave. / Background: Allogeneic Hematopoietic Stem Cell Transplantation (allo-HSCT) is a high potentially curative procedure to Acute Myeloid Leukemia (AML), mainly by the “graft-versus-leukemia” (GVL) effect, which leads to reduced risk of relapse. Nowadays, intermediate risk AML patients are submitted to this procedure if a matched sibling donor is available. Patients without a sibling donor are submitted to consolidation with chemotherapy, with a greater chance of relapse. It is believed that patients submitted to allo-HSCT have a greater overall survival and disease-free survival, even though it presents high morbidity and mortality rates. Risk stratification is extremely important to post-remission treatment choice. Molecular markers research is especially important in intermediate risk group, complementing cytogenetic evaluation to a better prognostic stratification and, although it is still not available in all health centers, it is more and more necessary. Materials and Methods: We evaluated intermediate risk AML patients in first Complete Remission (CR1) at the Hematology Service and Bone Marrow Transplantation from Hospital de Clínicas de Porto Alegre from April 1st 1999 to October 1st 2014, and which had, at least, a one year follow-up after treatment, by conducting a medical record review. Data was inserted in Microsoft Excel 2010 spreadsheets and after exported to SPSS v. 18.0 to statistical analysis. Results: Among the 69 patients analyzed, 45 were submitted to consolidation with chemotherapy (Intermediate risk AML – non allo-HSCT) and 24 of then submitted to allo-HSCT (Intermediate risk AML – allo-HSCT). The average age of Intermediate risk AML – non allo-HSCT was 47.8 years old and Intermediate risk AML – allo-HSCT was 35.5 years old, with statistically significance difference (P<0,001). There was no difference regard sex of patients. The median follow-up in the Intermediate risk AML – non allo-HSCT was 1.1 years (interquartile rage of 0.4 to 2.5) and in the Intermediate risk AML – allo-HSCT was 2.7 years (interquartile rage of 0.4 to 5.5), with no statistically significance difference in follow-up time distribution between groups (P=0.236). Intermediate risk AML – non allo-HSCT survival in 12 months was 52.3% and in the Intermediate risk AML – allo-HSCT was 62.5%. In 24 months, Intermediate risk AML – non allo-HSCT survival was 31.7% and in Intermediate risk AML – allo HSCT survival was 58.3% and in 5 years it was 21.1% and 53.8% respectively. Long- Rank test indicates a statistically significant difference in survival between groups after 5 years, with hazard ratio (HR) for death of 2.2 (IC95% 1.1 – 4.2), P=0.027, but when we adjust the relation to age, this association loses statistical significance (HR:1.6 95%CI: 1 – 1.1; P=0.246). Discussion: Data showed a better survival rate to the group submitted to allo-HSCT, but the group presented a lower average age. However, despite de loss of statistical significance, Hazard Ratio (HR), adjusted to age remains higher to the non allo-HSCT group. It can be explained by the small number of the sample. Identifying which patients will benefit from allo-HSCT becomes increasingly challenging. The use of molecular markers are important in the refinement of risk stratification in intermediate risk group, assisting in the decision. Moreover, with the advent of the possibility of nonmyeloablative conditioning as an alternative to older patients and with worst rates of comorbidity, and the better supporting therapy, we may be less conservative in indicating this procedure, identifying the patients who may obtain better results during treatment of such aggressive and serious disease.

Indiana University-Purdue University Indianapolis (IUPUI) / Internal tandem duplications in FMS-like receptor tyrosine kinase (FLT3-ITDs) are seen in approximately 25% of all acute myeloid leukemia (AML) patients. FLT3-ITDs induce FLT3 ligand (FL)-independent cellular hyperproliferation, promiscuous and aberrant activation of STAT5, and confer a poor prognosis in patients; however, the molecular mechanisms contributing to FLT3-ITD-induced malignancy remain largely unknown. The protein tyrosine phosphatase, Shp2, is important for normal hematopoiesis as well as hematopoietic stem cell (HSC) differentiation, engraftment, and self-renewal. Furthermore, FLT3-ITD- or constitutive active STAT5-expressing CD34+ cells demonstrate enhanced hematopoietic stem cell self-renewal. Together with the previous findings that Shp2 is critical for normal hematopoiesis, that dysregulated Shp2 function contributes to myeloid malignancies, and that Shp2 has been shown to interact with WT-FLT3 tyrosine 599, which is commonly duplicated in FLT3-ITDs, a positive role for Shp2 in FLT3-ITD-induced signaling and leukemogenesis is implied. I demonstrated that Shp2 is constitutively associated with the reported FLT3-ITDs, N51-FLT3 and N73-FLT3, compared to WT-FLT3; therefore, I hypothesized that increased Shp2 recruitment to N51-FLT3 or N73-FLT3 contributes to hyperproliferation and hyperactivation of STAT5. I also hypothesized that Shp2 cooperates with STAT5 to activate STAT5 transcriptional targets contributing to the up-regulation of pro-leukemic proteins. Finally, I hypothesized that reduction of Shp2 would result in diminished N51-FLT3-induced hyperproliferation and activation of STAT5 in vitro, and prevent FLT3-ITD-induced malignancy in vivo. I found that genetic disruption of Ptpn11, the gene encoding Shp2, or pharmacologic inhibition of Shp2 with the novel Shp2 inhibitor, II-B08, resulted in significantly reduced FLT3-ITD-induced hematopoietic cell hyperproliferation and STAT5 hyperphosphorylation. I also demonstrated a novel role of Shp2 in the nucleus of FLT3-ITD-expressing hematopoietic cells where Shp2 and STAT5 co-localized at the promoter region of STAT5-transcriptional target and pro-survival protein, Bcl-XL. Furthermore, using a Shp2flox/flox;Mx1Cre+ mouse model, I demonstrated that reduced Shp2 expression in hematopoietic cells resulted in an increased latency to and reduced severity of FLT3-ITD-induced malignancy. Collectively, these findings demonstrate that Shp2 plays an integral role in FLT3-ITD-induced malignancy and suggest that targeting Shp2 may be a future therapeutic option for treating FLT3-ITD-positive AML patients.

published_or_final_version / Medicine / Doctoral / Doctor of Philosophy

published_or_final_version / Medicine / Master / Master of Philosophy

Acute Myeloid Leukemia (AML), the most common form of acute leukemia in adults, is only curable in approximately 30% of all cases. Despite prognostic risk stratification using sub-typing and cytogenetic analysis to direct therapy, the mortality and relapse rate remains high. AML patients with normal karyotypes are defined as intermediate risk and are the most challenging to treat. Somatic mutations may be the key in refining prognostic stratification and providing useful therapeutic targets. The FMS-like tyrosine kinase 3 (FLT3) and Nucleophosmin (NPM1) genes have common mutated forms that are associated with overall survival and response to therapy. We assessed mutations in the FLT3 and NPM1 genes and their levels of expression in twenty eight AML patients in the presence and absence of HIV and their response to induction therapy. Furthermore, we used a novel technique, High Resolution Melting (HRM) Analysis to detect FLT3 Internal Tandem Duplications (ITD) and NPM1 exon 12 mutations. Five of the patients in this study were HIV positive, three of whom did not survive post-induction therapy. Of the AML patients, 17.9% were positive for the NPM1 mutation and 21% had mutated FLT3. Interestingly, the presence of the FLT3 and NPM1 mutations were coupled with an increase in expression levels of FLT3 and NPM1 from presentation to post-induction respectively and the loss of these mutations were coupled with a decrease in levels of expression from presentation to post-induction. However, an increase/decrease from presentation to post-induction did not necessarily denote the presence/absence of a mutation. Therefore, while mutational status of genes may generally confer mRNA levels, our results showed that there existed no definitive trend between mRNA levels of NPM1 and FLT3 expression and mutational status. We found that the HRM method was definitive for the simpler NPM1 mutation however detection of the FLT3-ITD mutation was challenging. There isn’t a clear distinction between mutated and non-mutated FLT3 due to the formation of hetero-duplexes during analysis, making detection highly subjective and error-prone. Sequencing allowed confirmation of mutated FLT3 and non-mutated FLT3 which were not in all instances in concordance with HRM analysis. The prognostic value in terms of overall survival of NPM1 and FLT3 mutations in this study is indefinite. Furthermore, the analysis of the HIV positive AML patients revealed no clear correlation between NPM1 and FLT3 levels of mRNA expression and mutational status. Also, the small number of HIV positive AML patients did not allow for conclusions to be made regarding HIV status and survival when affected with AML. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

Background: Children with Down syndrome (DS) have increased risk for developing AML (DS-AMKL), and they usually experience severe therapy-related toxicities compared to non DS-AMKL. Refractory/ relapsed disease has very poor outcome, and patients would benefit from novel, less toxic, therapeutic strategies that overcome resistance. Relapse/resistance are linked to cancer stem cells with high aldehyde dehydrogenase (ALDH) activity. The purpose of the present work was to study less toxic alternative therapeutic agents for relapsed/refractory DS-AMKL. Methods: Fourteen AML cell lines including the DS-AMKL CMY and CMK from relapsed/refractory AML were used. Cytarabine (Ara-C), bortezomib (BTZ), disulfiram/copper (DSF/Cu2+) were evaluated for cytotoxicity, depletion of ALDH-positive cells, and resistance. BTZ-resistant CMY and CMK variants were generated by continuous BTZ treatment. Cell viability was assessed using CellTiter-Glo((R)), ALDH activity by ALDELUOR(TM), and proteasome inhibition by western blot of ubiquitinated proteins and the Proteasome-Glo(TM) Chymotrypsin-Like (CT-like) assay, apoptosis by Annexin V Fluos/Propidium iodide staining, and mutations were detected using PCR, cloning and sequencing. Results: Ara-C-resistant AML cell lines were sensitive to BTZ and DSF/Cu2+. The Ara-C-resistant DS-AMKL CMY cells had a high percentage of ALDHbright "stem-like" populations that may underlie Ara-C resistance. One percent of these cells were still resistant to BTZ but sensitive to DSF/Cu2+. To understand the mechanism of BTZ resistance, BTZ resistant (CMY-BR) and (CMK-BR) were generated. A novel mutation PSMB5 Q62P underlied BTZ resistance, and was associated with an overexpression of the beta 5 proteasome subunit. BTZ-resistance conferred increased resistance toAra-C due to G1 arrest in the CMY-BR cells, which protected the cells from S-phase damage by Ara-C. CMY-BR and CMK-BR cells were cross-resistant to CFZ and MG-132 but sensitive to DSF/Cu2+. In this setting, DSF/Cu2+ induced apoptosis and proteasome inhibition independent of CT-like activity inhibition. Conclusions: We provide evidence that DSF/Cu2+ overcomes Ara-C and BTZ resistance in cell lines from DS-AMKL patients. A novel mutation underlying BTZ resistance was detected that may identify BTZ-resistant patients, who may not benefit from treatment with CFZ or Ara-C, but may be responsive to DSF/Cu2+. Our findings support the clinical development of DSF/Cu2+ as a less toxic efficacious treatment approach in patients with relapsed/refractory DS-AMKL.