Thesis (M. Phil.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 118-130) Also available in print.

O gene humano lysine methyltransferase 2E (KMT2E) pertence ao grupo Trithorax (TrxG) e age como proteína modificadora de histonas envolvida no controle transcricional de genes relacionados a hematopoiese. Foi previamente identificado como supressor tumoral, atuando sobre a diferenciação, proliferação e ciclo celular. DAMM et al. (2011) e LUCENA-ARAÚJO et al. (2014) descreveram a associação entre baixos níveis de expressão do gene KMT2E e desfechos desfavoráveis do tratamento de pacientes com leucemia mielóide aguda (LMA) e leucemia promielocítica aguda (LPA), respectivamente. O objetivo desse trabalho foi estudar os efeitos do aumento da expressão do gene KMT2E na leucemia mielóide aguda (LMA). Foi utilizada a linhagem celular U937, reconhecida como modelo de LMA, e o aumento da expressão do gene de interesse foi obtido por meio da transfecção das células com um vetor lentiviral contendo o cDNA codificante para a isoforma longa do gene (pCDH-MSCV-MCS-EF1-GFP+Puro, aqui chamado pMEG). As partículas lentivirais foram geradas por co-transfecção em células da linhagem HEK 293T, e posteriormente, titulados com a linhagem celular HT 1080. A expressão do gene e a presença da proteína foram confirmadas por qPCR e western blotting, respectivamente. Foram realizados ensaios funcionais de ciclo celular, proliferação, viabilidade, apoptose espontânea e induzida por trióxido de arsênico e luz ultravioleta e diferenciação celular induzida por 12-miristato 13-acetato de forbol (TPA), com as amostras U937 wild type (WT), U937 pMEG (U937 transduzidas com o vetor vazio) e U937 pMEG-KMT2E. Também foram realizadas mensurações da massa tumoral das células inoculadas em camundongos NSG. A expressão relativa do gene KMT2E na célula U937 pMEG-KMT2E foi 1000 vezes mais alta que na célula U937 sem a modificação genética. Os ensaios de diferenciação celular demonstraram que as células U937 pMEG-KMT2E apresentaram maior diferenciação em monócitos/macrófagos que as células controles, quando levada em consideração a marcação para o antígeno CD11c. A expressão induzida de KMT2E em células U937 não alterou a proliferação, viabilidade, ciclo celular, apoptose, ix espontânea ou induzida e o aspecto clonogênico in vitro, porém, foi associado a um maior crescimento tumoral em modelo animal. Nossa hipótese para justificar as diferenças entre os achados in vitro e in vivo é que o aumento da expressão de KMT2E, talvez por meio do aumento de CD11c, facilitou a interação entre as células e o microambiente, estimulando assim o crescimento tumoral in vivo. / The human lysine methyltransferase 2E (KMT2E) gene belongs to the Trithorax (TrxG) group and acts as a histone modifying protein participating in the transcriptional regulation of hematopoiesis-related genes. KMT2E has been previously described as a tumor suppressor, involved in cellular differentiation, proliferation and cell cycle progression. DAMM et al. (2011) and LUCENA-ARAÚJO et al. (2014) described the association between low levels of KMT2E gene expression and poor treatment outcomes in patients with acute myeloid leukemia (AML) and acute promyelocytic leukemia (APL), respectively. The aim of this project was to study the effects of high levels of KMT2E expression in acute myeloid leukemia (AML). For this purpose, the U937 AML cell line was used and an high expression of the gene was obtained by transfecting the cells with a lentiviral vector containing the cDNA encoding the long isoform of the gene (pCDH-MSCV-MCS-EF1- GFP + Pure, here called pMEG). The lentiviral particles were transfected into HEK 293T cells and the viral concentration was determined by titration using HT 1080 cells. The gene expression and the protein presence were confirmed by qPCR and western blotting, respectively. All experiments to determine the biological function of overexpressed KMT2E were conducted with U937 wild type, U937 pMEG (U937 transduced with the empty vector) and U937 pMEG-KMT2E cells. In-vitro the impact of overexpressed KMT2E was studied on cell cycle progression, proliferation and cell viability, spontaneous and induced apoptosis by arsenic trioxide and ultraviolet light and cell differentiation induced by 12-myristate 13-phorbol acetate (TPA). In vivo, the effect of overexpressed KMT2E was detected by comparing the tumor mass growth in NSG mice when inoculating U937 pMEG and pMEG-KMT2E cells in each flank of the same mouse. The relative expression level of the KMT2E gene in pMEG-KMT2E U937 cells was 1000 higher than in the wild type U937 strain. The cell differentiation assay revealed that U937 pMEG-KMT2E cells presented an increased monocyte/macrophage differentiation, when analyzing the CD11c antigen. Induced xi overexpression of KMT2E in U937 cells did not alter cell proliferation, cell viability, cell cycle progression, spontaneous or induced apoptosis or clonogenic appearance in vitro. However, the overexpression of KMT2E resulted in an increased tumor mass formation in vivo. Taking our discrepant in vitro and in vivo results into account, we could hypothesize that the increased expression of KMT2E, possibly caused by the enhanced expression of CD11c, favored the interaction between U937 pMEGKMT2E cells and their microenvironment, thereby stimulating tumor growth in vivo.

Acute myeloid leukemia (AML) often remains refractory to current chemotherapy and transplantation approaches despite many advances in our understanding of mechanisms in leukemogenesis. The bone marrow “niche” or microenvironment, however, may be permissive to leukemia development and studying interactions between the microenvironment and leukemia cells may provide new insight for therapeutic advances. Mesenchymal stem cells (MSCs) are central to the development and maintenance of the bone marrow niche and have been shown to have important functional alterations derived from patients with different hematological disorders. The extent to which MSCs derived from AML patients are altered remains unclear. The aim of this study was to detect changes occurring in MSCs obtained from human bone marrow in patients with AML by comparing their function and gene expression pattern with normal age-matched controls. MSCs expanded from patients diagnosed with acute leukemia were observed to have heterogeneous morphological characteristics compared to the healthy controls. Immunohistochemistry and flow data confirmed the typical cell surface immunophenotype of CD90+ CD105+ CD73+ CD34- CD45-, although MSCs from two patients with AML revealed reduced surface expression of CD105 and CD90 antigens respectively. Differentiation assays demonstrated the potential of MSCs from AML patients and healthy donors to differentiate into bone, fat and cartilage. However, the ability of MSCs from AML samples to support hematopoietic function of CD34+ progenitors was found to be impaired while the key hematopoietic genes were found to be differentially expressed on AML-MSCs compared to nMSCs. These studies indicate that there exist differences in the biologic profile of MSCs from AML patients compared to MSCs derived from healthy donors. The results described in the thesis provide a formulation for additional studies that may allow us to identify new targets for improved treatment of AML.

京都大学 / 0048 / 新制・課程博士 / 博士(社会健康医学) / 甲第22152号 / 社医博第100号 / 新制||社医||10(附属図書館) / 京都大学大学院医学研究科社会健康医学系専攻 / (主査)教授 川上 浩司, 教授 武藤 学, 教授 髙折 晃史 / 学位規則第4条第1項該当 / Doctor of Public Health / Kyoto University / DFAM

Acute myeloid leukemia (AML) is a hematopoietic malignancy characterized by great heterogeneity and clonal nature. In recent years, rapidly evolving next-generation sequencing methods provided a deep insight into the mutational background of AML. It was shown that ~ 44 % of AML patients harbor mutations in genes that regulate DNA methylation. So far, many researchers have tried to evaluate the prognostic significance of DNA methylation changes in AML, however, due to a great inconsistency in these studies, none of the reported markers were implemented into clinical practice. The aim of this work was to further investigate the DNA methylation changes in AML patients with specific mutations and their prognostic effect. Next, we wanted to develop a new approach for a complex evaluation of prognostically significant DNA methylation aberrations. In our first project, we assessed the overall DNA methylation, hydroxymethylation, and gene expression in AML patients with mutations in either DNMT3A or IDH1/2 or their combinations. We discovered that each genetic aberration is connected with a distinct pattern of DNA hydroxy-/methylation changes that are not entirely reflected in altered gene expression. Patients with mutations in both genes exhibited a mixed DNA methylation profile most similar to healthy...

Acute myeloid leukemia(AML) is the most common acute leukemia among adults in the United states with approximately 19,940 people being diagnosed of this disease in 2020 and 11,180 deaths. It is a heterogenous group of malignancy characterized by clonal expansion of blast with myeloid lineage in the bone marrow, peripheral blood and/or other tissues. Our patient is a 79-year-old male who presented to the hospital with reports of sharp, throbbing low back pain for one month, moderately controlled with pain medications. He reported 5 lb. weight loss with decreased appetite over one month but denied other constitutional symptoms. MRI Lumbar spine revealed multiple foci of marrow signal abnormality compatible with extensive metastatic disease. CT chest, abdomen and pelvis did not show any lesions concerning for primary or metastatic malignancy. CBC revealed normal WBC count, platelet count and hemoglobin level (with macrocytosis, MCV 104.7). Initial work up including Vitamin B12 and folic acid level, TSH, SPEP/IFE, serum light chain ratio and quantitative immunoglobulins were within normal limits. Pathology from a CT guided bone biopsy of the L spine lesion was concerning for high grade myeloid neoplasm. Patient had a bone marrow biopsy done at another hospital which was read as most consistent with acute myeloid leukemia (AML) with monocytic differentiation, with findings of hypocellular marrow, extensive fibrosis with focal areas of large clusters of immature cells, positive for MPO, CD33, CD43 and CD 56, Ki-67 of 60-80%. Cytogenetics showed an abnormal male karyotype with trisomy 8. FISH was negative for other AML or MDS related abnormalities. Given the above findings of AML and advanced age, patient was started on treatment with hypomethylating agent Decitabine along with BCL-2 inhibitor, Venetoclax. A repeat bone marrow biopsy after two cycles of the above regimen revealed progressive disease with extensive fibrosis and 80-90% blast on a core biopsy sample. Due to poor response to above regimen, lack of effective treatment options in older patients with AML and declining functional status, decision was made to pursue best supportive care. AML usually presents with symptoms of fevers, fatigue, dyspnea or bleeding. Skeletal lesions are usually associated with a diagnosis of multiple myeloma, or other solid organ malignancies and rare in AML. Extra medullary involvement of AML is known to happen in 2.5%-9% of patients and is termed as Myeloid Sarcoma. Due to the low incidence, prospective study data is limited. This entity is treated similarly to AML, depending on risk stratification by cytogenetics, age and targetable mutations which also govern its prognosis. This case highlights the importance of increased awareness and high index of suspicion among medical providers regarding this atypical presentation of AML since if missed or misdiagnosed could delay treatment and lead to poor outcomes.

No description available.

Yes / The HOX genes encode a family of transcription factors that have key roles in both development and malignancy. Disrupting the interaction between HOX proteins and their binding partner, PBX, has been shown to cause apoptotic cell death in a range of solid tumors. However, despite HOX proteins playing a particularly significant role in acute myeloid leukemia (AML), the relationship between HOX gene expression and patient survival has not been evaluated (with the exception of HOXA9), and the mechanism by which HOX/PBX inhibition induces cell death in this malignancy is not well understood. In this study, we show that the expression of HOXA5, HOXB2, HOXB4, HOXB9, and HOXC9, but not HOXA9, in primary AML samples is significantly related to survival. Furthermore, the previously described inhibitor of HOX/PBX dimerization, HXR9, is cytotoxic to both AML-derived cell lines and primary AML cells from patients. The mechanism of cell death is not dependent on apoptosis but instead involves a regulated form of necrosis referred to as necroptosis. HXR9-induced necroptosis is enhanced by inhibitors of protein kinase C (PKC) signaling, and HXR9 combined with the PKC inhibitor Ro31 causes a significantly greater reduction in tumor growth compared to either reagent alone. / Funded in part through a grant to RA from the Cultural Bureau of the Kingdom of Saudi Arabia.

In patients with acute myeloid leukemia (AML), cytarabine-based chemotherapy usually achieves remission, but this is commonly followed by relapse and chemo-resistance. In this study, we aim to establish next-generation sequencing (NGS)-based microRNA expression profiling and pathway analysis to identify pathways regulated differentially between chemo-sensitive and -resistant AML as potential therapeutic targets. MicroRNA expression profiles differ significantly between chemo-sensitive and chemo-resistant AML cells and reflect differences in the activity of intracellular signaling cascades. Alterations in signaling pathway activities contribute to treatment resistance and thus represent potential drug targets. Our microRNA-led approach indicates a role for activin receptor type 2A in ARA-C resistance of AML cells and suggests activin receptor signaling to be a candidate pathway for targeted therapy.

No description available.