CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / O esqueleto quinona foi identificado como um importante grupo farmacofÃrico para atividade citotÃxica de vÃrios compostos utilizados na clÃnica, constituindo ainda uma das maiores classes de agentes anticÃncer. A β-lapachona à uma das quinonas mais estudadas nos Ãltimos anos. Suas aplicaÃÃes mais importantes estÃo relacionadas Ãs aÃÃes contra vÃrias cÃlulas tumorais. Seu derivado, nor-β-lapachona (composto 1), tem atividade anticÃncer similar. Assim, o objetivo desse trabalho foi avaliar o mecanismo de aÃÃo envolvido na citotoxicidade do composto 1 e de seu derivado nitrofenilamino (composto 2) em cÃlulas leucÃmicas HL-60. Inicialmente foi investigado o efeito desses compostos na viabilidade de cÃlulas HL-60 apÃs 24 horas de incubaÃÃo, mostrando CI50 de 2,92 e 0,48 μM para os compostos 1 e 2, respectivamente. Acerca da seletividade celular, o composto 1 mostrou forte seletividade para cÃlulas tumorais, enquanto que o seu derivado foi apenas parcialmente seletivo. Estudos feitos em cÃlulas HL-60 indicaram que o composto 2 induz morte celular por apoptose como mostrado pelas mudanÃas morfolÃgicas, fragmentaÃÃo do DNA, despolarizaÃÃo da membrana mitocondrial e externalizaÃÃo da fosfatidilserina. Ambos compostos aumentaram a geraÃÃo de espÃcies reativas de oxigÃnio (EROs). Nossos resultados sugerem que a introduÃÃo do radical nitrofenilamino na posiÃÃo 3 do anel furano aumenta a citotoxicidade da nor--lapachona em cÃlulas HL-60. Esses achados apontam para o potencial dessas quinonas sintÃticas como modelo para a produÃÃo de novos compostos com propriedades anticÃncer. / The quinone moiety has been identified as an important pharmacophoric group for cytotoxic activity of several compounds clinically used, constituting just one of the major classes of anticancer agents. β-lapachone is one of the most studied quinones in the last years. Its most important applications are related to its action against several cancer cells. Its derivative, nor-β-lapachone (compound 1), has similar anticancer activity. Thus, the aim of this work was to evaluate the mechanism of action involved in nor--lapachone and its nitrophenylamino derivative (compound 2) cytotoxicity in a leukemia cells model of HL-60 cell line. Initially it was investigated the effect of both the compounds on HL-60 cells viability after 24 hours of incubation, showing IC50 values of 2.92 and 0.48 μM to compounds 1 and 2, respectively. Considering the selectivity, compound 1 showed strong selectivity to cancer cells, while its derivative was only partially selective. Studies performed in HL-60 cells, after 24 hours, indicated that compound 2 induces cell death by apoptosis as showed by morphological changes, DNA fragmentation, mitochondrial membrane depolarization and phosphatidylserine externalization. Both tested compounds increased generation of reactive oxygen species (ROS). Our results suggest that a nitrophenylamino radical introduction at position 3 of the furane ring enhances the cytotoxicity of nor--lapachone in HL-60 cell line. These findings highlight the potential of these synthetic quinones as prototypes molecules to produce new compounds with anticancer properties.

Ping Zhang. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (p. 131-144). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

Thesis (M.Sc.). / Written for the Faculty of Medicine, Division of Experimental Medicine. Title from title page of PDF (viewed 2008/05/14). Includes bibliographical references.

La télomérase est présente dans un nombre limité de cellules, telles que la plupart des cellules cancéreuses où son activité est indispensable pour l’immortalisation de ces dernières. C’est pourquoi cette enzyme a été proposée comme cible prometteuse pour des thérapies anticancéreuses. Ainsi, il est d’un intérêt certain d’identifier les mécanismes par lesquels elle est régulée, notamment via sa sous-unité catalytique, hTERT. Les rétinoïdes sont des inducteurs bien connus de la maturation granulocytaire associée à une répression de hTERT dans les blastes de leucémie aiguë promyélocytaire (LAP). Dans une lignée cellulaire LAP résistant à la maturation induite par les rétinoïdes (NB4-LR1), a précédemment été identifiée une nouvelle voie de répression transcriptionnelle de hTERT en absence de différenciation. De plus, mon laboratoire d’accueil a isolé un variant de la lignée NB4-LR1 résistant à cette répression transcriptionnelle de hTERT, la lignée NB4-LR1SFD. Ensemble, ces lignées cellulaires, qui se comportent différemment face à un traitement à l’ATRA, fournissent un outil unique et puissant pour obtenir plus d’informations sur plusieurs problèmes de la régulation de la biologie moléculaire de la télomérase. Dans cette étude, en utilisant plusieurs approches complémentaires (immunoprécipitation de la chromatine combinée à une technique d’analyse à haut débit du positionnement des nucléosomes et de la méthylation de l’ADN et une approche de FISH), j’ai pu obtenir une vue intégrée des événements épigénétiques qui promeuvent la transition du promoteur de hTERT d’un état silencieux à un état actif et inversement. Cette information sera cruciale pour le développement de stratégies anticancéreuses ciblant l’expression de hTERT. / Telomerase is present in a limited number of cells, most of them cancerous where its activity is crucial for their immortalisation. Thus, that enzyme has been proposed as a promising target for anticancer therapies. Therefore, it is of great interest to identify the mechanisms by which it is regulated, notably through its catalytic subunit hTERT. Retinoids are well-known inducers of granulocytic maturation associated with hTERT repression in acute promyelocytic leukemia (APL) blasts. However, in NB4-LR1, a maturation-resistant APL cell line, was previously identified a new pathway of retinoid-induced hTERT transcriptional repression independent of differentiation. Furthermore, my host lab reported the isolation of a variant of NB4-LR1 cells resistant to this repression: NB4-LR1SFD. These two cell lines, which behave distinctly in response to ATRA treatment, provide a unique and interesting tool to gain further insights into the molecular biology of telomerase regulation. In this thesis project, using several complementary approaches (chromatin immunoprecipitation combined to a high-resolution, single-molecule nucleosome positioning assay and DNA methylation, and a FISH approach) allowed me to shed more light on the integrated epigenetic events that lead to hTERT promoter transition from its silent to its active state and vice versa. The information obtained could be crucial for the development of anticancer strategies targeting hTERT expression.

INTRODUÇÃO: A leucemia promielocítica aguda (LPA) é um subtipo distinto de leucemia mielóide aguda (LMA), caracterizado pela presença de um acúmulo de promielócitos anormais na medula óssea e/ou sangue periférico, riscos de coagulopatias e por alterações cromossômicas estruturais envolvendo sempre o locus gênico para o receptor alfa do ácido retinóico (RAR). Corresponde morfologicamente aos subtipos M3 e M3variante de LMA, segundo a Classificação Franco- Américo- Britânica (FAB) e ao subtipo de LMA associada à translocação recíproca e balanceada entre os cromossomos 15 e 17[t(15;17)] e variantes, segundo a classificação da Organização Mundial de Saúde. O curso clínico da LPA tem sido modificado, nos últimos anos, de uma leucemia aguda rapidamente fatal para um dos mais curáveis subtipos de LMA. A introdução de agentes terapêuticos que atuam diretamente na lesão molecular, como o ATRA e o Trióxido de Arsênico, teve grande impacto na sobrevida da LPA. A eficácia do tratamento é dependente do rearranjo genético presente nas células leucêmicas, o diagnóstico morfológico é sugestivo da alteração genética, devendo ser rapidamente confirmado por técnicas de citogenética molecular. MÉTODOS: Utilizando a citogenética convencional e molecular (FISH) com sondas de fusão para o rearranjo PML-RAR e de ruptura para o gene RAR, analisou-se 62 pacientes portadores de LPA, diagnosticados por estudo morfológico/imunofetípico no HC-FM/USP entre os anos de 1997 a 2006. RESULTADOS: Dos 62 pacientes analisados, 37 (59,7%) apresentaram a t(15;17)(q22;q21) visível no cariótipo; destes, 26 (42,0%) apresentaram a t(15;17) como anormalidade clonal isolada, 10 (16,1%) apresentaram outras alterações cromossômicas clonais em adição a t(15;17) e um paciente (1,6%) apresentou uma variante complexa da t(15;17). Dezoito pacientes (29%) tiveram a confirmação da presença da t(15;17)-rearranjo PML-RAR através da técnica de FISH-fusão e sete (11,3%) não apresentaram ruptura no RAR. Ausência de sangramento ao diagnóstico (p<0,02) e a presença de morfologia M3v (p<0,01) se associaram à ausência ruptura no RAR. A taxa de sobrevida global (SG) em dois anos, entre os 55 pacientes que apresentaram a t(15;17)-rearranjo- PML-RAR ao diagnóstico citogenético, foi de 49,28%. Duas variáveis prognósticas mostraram estar estatisticamente relacionadas à pior taxa de SG nesse estudo: idade acima de 60 anos e presença de morfologia de M3v. A taxa de Sobrevida Livre de Doença em dois anos nesses pacientes foi de 72,10%.CONCLUSÃO: Cerca de 11% dos pacientes diagnosticados para LPA, através de estudo morfológico/imunofenotípico, não apresentaram diagnóstico citogenético compatível para esta doença. Na ausência de sangramento ao diagnóstico e na presença de morfologia M3v o teste de FISH deve ser priorizado. / INTRODUCTION: Acute promyelocytic leukemia (APL) is a distinct subtype of acute myeloid leukemia (AML), characterized by clonal expansion of myeloid precursors blocked at promyelocytic stage, risks of coagulopathy and presence of chromosomal translocations involving RAR (retinoic acid receptor ) gene. Corresponds to the M3 and M3variant subtypes of AML, according to the French-American-British (FAB) classification and the subtype of AML associated with balanced reciprocal translocation between chromosomes 15 and 17 [t (15; 17)] and variants, according to the World Health Organization classification. The clinical APL course has been changed in late years, from highly fatal to highly curable subtype of AML. The introduction of therapeutic agents that act directly on the molecular lesion, such as ATRA and arsenic trioxide, had a great impact on survival of APL. The efficacy of treatment is dependent on genetic rearrangement present in the leukemia cells, the morphologic diagnosis although predictive of the specific genetic lesion genetic, should be quickly confirmed by molecular techniques. METHODS: We analysed cytogenetics findings in 62 patients diagnosed as promyelocytic leukemia by morphological and immunophenotypic studies at the Hematology Service of Clinical Hospital of Sao Paulo Medical School from 1997 to 2006. For this, we used karyotype and FISH with PML-RARA fusion translocation and RARA break-apart probes. RESULTS: Of the 62 patients studied, 59.7% showed the t(15;17)(q22;q21) visible in the karyotype [42.0% had t(15;17) as the sole clonal abnormality, 16.1% showed other additional abnormalities and 1.6% had a complex variant of t(15;17)], 29% had the confirmation of the rearrangement PML-RAR through the FISH-fusion technique and 11.3% showed no break in RAR. No bleeding at diagnosis (p<0.02) and the presence of M3v morphology (p<0.01) were associated to no RAR rearrangement. The 24months overall survival of 55 patients with t(15;17) confirmed by cytogenetics was 49.28%. Two parameters were associated to worse rate of overall survival in this study: age > 60 years and M3v morphology . The 24 months disease-free survival was 72.10%. CONCLUSION: 11,3% of patients diagnosed as promyelocytic leukemia by morphological and immunophenotypic studies, showed no consistent cytogenetic diagnosis for this disease. In the absence of bleeding at diagnosis and in the presence of the M3v morphology, FISH test should be prioritized.

INTRODUÇÃO: A leucemia promielocítica aguda (LPA) é um subtipo distinto de leucemia mielóide aguda (LMA), caracterizado pela presença de um acúmulo de promielócitos anormais na medula óssea e/ou sangue periférico, riscos de coagulopatias e por alterações cromossômicas estruturais envolvendo sempre o locus gênico para o receptor alfa do ácido retinóico (RAR). Corresponde morfologicamente aos subtipos M3 e M3variante de LMA, segundo a Classificação Franco- Américo- Britânica (FAB) e ao subtipo de LMA associada à translocação recíproca e balanceada entre os cromossomos 15 e 17[t(15;17)] e variantes, segundo a classificação da Organização Mundial de Saúde. O curso clínico da LPA tem sido modificado, nos últimos anos, de uma leucemia aguda rapidamente fatal para um dos mais curáveis subtipos de LMA. A introdução de agentes terapêuticos que atuam diretamente na lesão molecular, como o ATRA e o Trióxido de Arsênico, teve grande impacto na sobrevida da LPA. A eficácia do tratamento é dependente do rearranjo genético presente nas células leucêmicas, o diagnóstico morfológico é sugestivo da alteração genética, devendo ser rapidamente confirmado por técnicas de citogenética molecular. MÉTODOS: Utilizando a citogenética convencional e molecular (FISH) com sondas de fusão para o rearranjo PML-RAR e de ruptura para o gene RAR, analisou-se 62 pacientes portadores de LPA, diagnosticados por estudo morfológico/imunofetípico no HC-FM/USP entre os anos de 1997 a 2006. RESULTADOS: Dos 62 pacientes analisados, 37 (59,7%) apresentaram a t(15;17)(q22;q21) visível no cariótipo; destes, 26 (42,0%) apresentaram a t(15;17) como anormalidade clonal isolada, 10 (16,1%) apresentaram outras alterações cromossômicas clonais em adição a t(15;17) e um paciente (1,6%) apresentou uma variante complexa da t(15;17). Dezoito pacientes (29%) tiveram a confirmação da presença da t(15;17)-rearranjo PML-RAR através da técnica de FISH-fusão e sete (11,3%) não apresentaram ruptura no RAR. Ausência de sangramento ao diagnóstico (p<0,02) e a presença de morfologia M3v (p<0,01) se associaram à ausência ruptura no RAR. A taxa de sobrevida global (SG) em dois anos, entre os 55 pacientes que apresentaram a t(15;17)-rearranjo- PML-RAR ao diagnóstico citogenético, foi de 49,28%. Duas variáveis prognósticas mostraram estar estatisticamente relacionadas à pior taxa de SG nesse estudo: idade acima de 60 anos e presença de morfologia de M3v. A taxa de Sobrevida Livre de Doença em dois anos nesses pacientes foi de 72,10%.CONCLUSÃO: Cerca de 11% dos pacientes diagnosticados para LPA, através de estudo morfológico/imunofenotípico, não apresentaram diagnóstico citogenético compatível para esta doença. Na ausência de sangramento ao diagnóstico e na presença de morfologia M3v o teste de FISH deve ser priorizado. / INTRODUCTION: Acute promyelocytic leukemia (APL) is a distinct subtype of acute myeloid leukemia (AML), characterized by clonal expansion of myeloid precursors blocked at promyelocytic stage, risks of coagulopathy and presence of chromosomal translocations involving RAR (retinoic acid receptor ) gene. Corresponds to the M3 and M3variant subtypes of AML, according to the French-American-British (FAB) classification and the subtype of AML associated with balanced reciprocal translocation between chromosomes 15 and 17 [t (15; 17)] and variants, according to the World Health Organization classification. The clinical APL course has been changed in late years, from highly fatal to highly curable subtype of AML. The introduction of therapeutic agents that act directly on the molecular lesion, such as ATRA and arsenic trioxide, had a great impact on survival of APL. The efficacy of treatment is dependent on genetic rearrangement present in the leukemia cells, the morphologic diagnosis although predictive of the specific genetic lesion genetic, should be quickly confirmed by molecular techniques. METHODS: We analysed cytogenetics findings in 62 patients diagnosed as promyelocytic leukemia by morphological and immunophenotypic studies at the Hematology Service of Clinical Hospital of Sao Paulo Medical School from 1997 to 2006. For this, we used karyotype and FISH with PML-RARA fusion translocation and RARA break-apart probes. RESULTS: Of the 62 patients studied, 59.7% showed the t(15;17)(q22;q21) visible in the karyotype [42.0% had t(15;17) as the sole clonal abnormality, 16.1% showed other additional abnormalities and 1.6% had a complex variant of t(15;17)], 29% had the confirmation of the rearrangement PML-RAR through the FISH-fusion technique and 11.3% showed no break in RAR. No bleeding at diagnosis (p<0.02) and the presence of M3v morphology (p<0.01) were associated to no RAR rearrangement. The 24months overall survival of 55 patients with t(15;17) confirmed by cytogenetics was 49.28%. Two parameters were associated to worse rate of overall survival in this study: age > 60 years and M3v morphology . The 24 months disease-free survival was 72.10%. CONCLUSION: 11,3% of patients diagnosed as promyelocytic leukemia by morphological and immunophenotypic studies, showed no consistent cytogenetic diagnosis for this disease. In the absence of bleeding at diagnosis and in the presence of the M3v morphology, FISH test should be prioritized.

Interactions between the retinoic acid receptor alpha (RARalpha) and coregulators play a key role in coordinating gene transcription and myeloid differentiation. In acute promyelocytic leukemia (APL), RARalpha is fused with the promyelocytic leukemia (PML) gene, resulting in the expression of the fusion protein PML/RARalpha. Here, I report that topoisomerase II beta (topoIIbeta) associates with and negatively modulates PML/RARalpha and RARalpha transcriptional activity, and increased levels and association of topoIIbeta cause resistance to retinoic acid (RA) in APL cell lines. Knock down of topoIIbeta was able to overcome resistance by permitting RA-induced differentiation and increased RA-gene expression. Overexpression of topoIIbeta, in clones from an RA-sensitive cell line, conferred resistance by a reduction in RA-induced expression of target genes and differentiation. Chromatin immunoprecipitation assays indicate that topoIIbeta is bound to an RA-response element, and inhibition of topoIIbeta causes hyper-acetylation of histone 3 at lysine 9 and activation of transcription. These results identify a novel mechanism of resistance in APL and provide further insights to the role of topoIIbeta in gene regulation and differentiation. / Studies to determine the mechanism by which topoIIbeta protein is regulated found that levels of protein kinase C delta (PKCdelta) correlated with topoIIbeta protein expression. Moreover, activation of PKCdelta, by RA or PMA, led to an increase of topoIIbeta protein levels. Most notably, in NB4-MR2 cells, we observed increased phosphorylation levels of threonine 505 on PKCdelta, a marker of activation. Inhibition of PKCdelta was able to overcome the topoIIbeta repressive effects on RA-target genes. In addition, the combination of RA and PKCdelta inhibition led to increased expression of the granulocytic marker, CD11c, in NB4 and NB4-MR2 cells. These results suggest that PKCdelta regulates topoIIbeta expression, and a constitutively active PKCdelta in the NB4-MR2 cell line leads to overexpression of topoIIbeta. / In conclusion, these studies demonstrate that topoIIbeta associates with RARalpha, binds to RAREs and plays a critical role in RA dependent transcriptional regulation and granulocytic differentiation. In addition, I show that topoIIbeta overexpression leads to RA resistance and provide evidence that topoIIbeta protein levels are regulated via a mechanism involving the PKCdelta pathway. This work has contributed to an enhanced understanding of the role of topoIIbeta in gene regulation and brings novel perspectives in the treatment of RA-resistance in APL.

No description available.

Les leucémies aiguës myéloïdes (LAM) sont des proliférations malignes de progéniteurs bloqués lors de la différenciation myéloïde. Le caryotype des blastes leucémiques identifie 3 groupes pronostiques distincts. Parmi les LAM à risque cytogénétique favorable, figurent les leucémies aiguës promyélocytaires (LAP), et celles avec inv(16) ou t(8;21). Les micro-ARNs sont des acteurs clef de l’hématopoïèse et sont aussi impliqués dans la leucémogénèse des LAM. Ils sont très stables dans le sérum et sont utilisés comme biomarqueurs dans les cancers. Le but de cette thèse était d’évaluer si une caractérisation pangénomique des micro-ARNs sériques permettait de distinguer ces 3 types de LAM entre elles ainsi que les LAM avec caryotype normal (NK-AML); d’identifier des micro-ARNs circulants fortement surexprimés dans les NK-AML par rapport à des sujets sains, pour une utilisation ultérieure comme marqueurs de maladie résiduelle; et de mieux préciser le pronostic des NK-AML. Ainsi, nous avons identifié une signature sérique spécifique des LAP liée à une dérégulation des micro-ARNs localisés dans la région DLK1-DIO3 soumise à l’empreinte, en 14q32. Ces micro-ARNs, dont l’origine était le blaste leucémique, étaient corrélés aux facteurs pronostiques connus des LAP. Par ailleurs, deux micro-ARNs, miR-10a-3p et miR-196b-5p, distinguant les NK-AML des LAM avec inv(16) ou t(8 ;21) ont été montré surexprimés dans les NK-LAM avec une mutation de NPM1 et/ou de FLT3-ITD. Enfin l’expression de ces deux micro-ARNs est corrélée à la dérégulation transcriptionnelle et à la méthylation de l’ADN affectant les gènes HOX et TALE. En conclusion, cette étude des micro-ARNs sériques ouvre un nouveau champ d’exploration à visée pronostique dans les LAM. / Acute myeloid leukaemia (AML) is a malignant proliferation of progenitors blocked during myeloid differentiation. The karyotype of the leukemic blasts identified three distinct prognostic groups. Among the favourable risk cytogenetics AML include acute promyelocytic leukaemia (APL), and those with inv (16) or t (8; 21). Micro-RNAs are key players in hematopoiesis and are also involved in leukemogenesis of AML. They are very stable in serum and used as biomarkers in cancers. The aim of this thesis was to evaluate whether a genome-wide characterization of serum micro-RNAs possible to distinguish these three types of AML them as well as AML with normal karyotype (NK-AML); identify micro-RNAs circulating highly overexpressed in NK-AML compared to healthy subjects, for later use as markers of residual disease; and to better define the prognosis of NK-AML. Thus, we have identified a specific serum signing of LAP related to a deregulation of micro-RNAs located in the DLK1-DIO3 under the imprinting, in 14q32. These micro-RNAs whose origin was the leukemic blasts were correlated with known prognosis factors of APL. In addition, two micro-RNAs, miR-10a-3p and miR-196b-5p, distinguishing the NK-AML with inv (16)-AML or t (8; 21)-AML have been shown overexpressed in NK-AML with mutation NPM1 and / or FLT3-ITD. Finally the expression of these two micro-RNAs correlates withtranscriptional deregulation and DNA methylation affectingTALE and HOX genes. In conclusion, this study of serum microRNAs opens a new field of exploration to assess the prognosis in AML.