RESUMO
Increasing recognition of germline DDX41 variants in patients with hematological malignancies prompted us to provide DDX41-specific recommendations for diagnosis, surveillance, and treatment. Causative germline variants in the DDX41 predispose to the development of myeloid neoplasms (MNs), especially myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML). Almost 3%-5% of all patients with MDS or AML carry a pathogenic or likely pathogenic germline DDX41 variant, while half of them acquire a somatic second hit in the other allele. DDX41-associated MNs exhibit unique clinical characteristics compared to other hematological malignancies with germline predisposition: MNs occur mostly at advanced age and follow an indolent clinical course. Male carriers are more prone to develop MDS or AML than females. DDX41-associated MN is often hypoplastic, and the malignancy may be preceded by cytopenias.
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Chromosomal rearrangements involving Janus kinase 2 (JAK2) are rare but recurrent findings in lymphoid or myeloid neoplasia. Detection of JAK2 fusion genes is important as patients with aberrantly activated JAK2 may benefit from treatment with tyrosine kinase inhibitors such as ruxolitinib. Here, we report a novel fusion gene between the transcriptional co-repressor-encoding gene transducin-like enhancer of split 3 (TLE3) and JAK2 in a patient initially diagnosed with chronic eosinophilic leukemia with additional mutations in PTPN11 and NRAS. The patient was successfully treated with the JAK2 inhibitor ruxolitinib for 8 months before additional somatic mutations were acquired and the disease progressed into an acute lymphoblastic T-cell leukemia/lymphoma. The present case shows similarities to previously reported cases with PCM1::JAK2 and BCR::JAK2 with regard to disease phenotype and response to ruxolitinib, and importantly, provides an example that also patients harboring other JAK2 fusion genes may benefit from treatment with JAK2 inhibitors.
Assuntos
Janus Quinase 2 , Nitrilas , Proteínas de Fusão Oncogênica , Pirimidinas , Humanos , Janus Quinase 2/genética , Janus Quinase 2/antagonistas & inibidores , Proteínas de Fusão Oncogênica/genética , Nitrilas/uso terapêutico , Pirimidinas/uso terapêutico , Masculino , Pirazóis/uso terapêutico , Eosinofilia/genética , Eosinofilia/tratamento farmacológico , Eosinofilia/patologia , Inibidores de Proteínas Quinases/uso terapêuticoRESUMO
B cell progenitor acute lymphoblastic leukemia (BCP-ALL) is the most common childhood malignancy, driven by multiple genetic alterations that cause maturation arrest and accumulation of abnormal progenitor B cells. Current treatment protocols with chemotherapy have led to favorable outcomes but are associated with significant toxicity and risk of side effects, highlighting the necessity for highly effective, less toxic, targeted drugs, even in subtypes with a favorable outcome. Here, we used multimodal single-cell sequencing to delineate the transcriptional, epigenetic, and immunophenotypic characteristics of 23 childhood BCP-ALLs, belonging to the BCR::ABL1-positive, ETV6::RUNX1-positive, high hyperdiploid, and recently discovered DUX4-rearranged (DUX4-r) subtypes. Projection of the ALL cells along the normal hematopoietic differentiation axis revealed a diversity in the maturation pattern between the different BCP-ALL subtypes. Whereas the BCR::ABL1-, ETV6::RUNX1-positive, and high hyperdiploidy cells mainly showed similarities to normal pro-B cells, the DUX4-r ALL cells also displayed transcriptional signatures resembling mature B cells. Focusing on the DUX4-r subtype, we found that the blast population displayed multilineage priming toward non-hematopoietic cells, myeloid, and T cell lineages, but also an activation of PI3K/AKT signaling that sensitized the cells to PI3K inhibition in vivo. Given the multilineage priming of the DUX4-r blasts with aberrant expression of the myeloid marker CD371 (CLL-1), we generated chimeric antigen receptor T cells, which effectively eliminated DUX4-r ALL cells in vivo. These results provide a detailed characterization of BCP-ALL at the single-cell level and reveal therapeutic vulnerabilities in the DUX4-r subtype with implications for the understanding of ALL biology and new therapeutic strategies.
RESUMO
Mutated nucleophosmin 1 (NPM1) is the most common genetic alteration in acute myeloid leukemia (AML), found in â¼30% of cases. Although mutations in this gene are considered favorable according to current risk stratification guidelines, a large fraction of patients will experience relapse, demonstrating the urgent need for new treatment options. Therefore, we aimed to identify cell surface proteins specifically expressed on NPM1-mutated AML cells, allowing for potential targeting with antibody-based therapies. Herein, we report on an arrayed flow cytometry-based screen directed to 362 cell surface markers. In comparing the cell surface expression on NPM1-mutated AML cells with primitive (CD34+ CD38-) normal bone marrow cells, we identified the complement receptor C3AR as being specifically expressed in NPM1-mutated AML. By flow cytometry and single-cell RNA sequencing, we further show that normal hematopoietic stem and progenitor cells lack detectable C3AR gene and protein expression, making it particularly suitable as a target for antibody therapy. We also demonstrate that C3AR in combination with GPR56 distinguishes the leukemic stem cells (LSCs) in NPM1-mutated AML from the normal hematopoietic stem cells, defining the LSC population, as shown by transplantation into immunodeficient mice. Mechanistically, the stimulation of C3AR-expressing cells with C3a, the ligand of C3AR, leads to the activation of ERK1/2 and increased survival of AML cells, suggesting that this is an important signaling axis in this subtype of AML. Finally, we show that antibodies directed against C3AR efficiently elicit natural killer cell-mediated killing of primary AML cells ex vivo, highlighting C3AR as a candidate therapeutic target in NPM1-mutated AML.
Assuntos
Leucemia Mieloide Aguda , Proteínas Nucleares , Camundongos , Animais , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Nucleofosmina , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/terapia , Leucemia Mieloide Aguda/metabolismo , Transdução de Sinais , Antígenos CD34 , Receptores Acoplados a Proteínas GAssuntos
Leucemia-Linfoma Linfoblástico de Células Precursoras B , Leucemia-Linfoma Linfoblástico de Células Precursoras , Criança , Humanos , Subunidade alfa 2 de Fator de Ligação ao Core/genética , Leucemia-Linfoma Linfoblástico de Células Precursoras/genética , Proteínas de Fusão Oncogênica/genética , Proteína Acessória do Receptor de Interleucina-1RESUMO
Clonal heterogeneity and evolution has major implications for disease progression and relapse in acute myeloid leukemia (AML). To model clonal dynamics in vivo, we serially transplanted 23 AML cases to immunodeficient mice and followed clonal composition for up to 15 months by whole-exome sequencing of 84 xenografts across two generations. We demonstrate vast changes in clonality that both progress and reverse over time, and define five patterns of clonal dynamics: Monoclonal, Stable, Loss, Expansion and Burst. We also show that subclonal expansion in vivo correlates with a more adverse prognosis. Furthermore, clonal expansion enabled detection of very rare clones with AML driver mutations that were undetectable by sequencing at diagnosis, demonstrating that the vast majority of AML cases harbor multiple clones already at diagnosis. Finally, the rise and fall of related clones enabled deconstruction of the complex evolutionary hierarchies of the clones that compete to shape AML over time.
Assuntos
Evolução Clonal , Leucemia Mieloide Aguda/genética , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Progressão da Doença , Feminino , Humanos , Leucemia Mieloide Aguda/patologia , Masculino , Camundongos , Pessoa de Meia-Idade , Mutação , Sequenciamento do ExomaAssuntos
Carcinogênese/genética , Histona-Lisina N-Metiltransferase/genética , Leucemia Mieloide Aguda/genética , Proteína de Leucina Linfoide-Mieloide/genética , Proteínas Nucleares/genética , Tirosina Quinase 3 Semelhante a fms/genética , Animais , Antígenos CD34/genética , Rearranjo Gênico/genética , Xenoenxertos , Humanos , Camundongos , Camundongos Endogâmicos NODRESUMO
Tyrosine kinase inhibitors (TKIs) are highly effective for the treatment of chronic myeloid leukemia (CML), but very few patients are cured. The major drawbacks regarding TKIs are their low efficacy in eradicating the leukemic stem cells responsible for disease maintenance and relapse upon drug cessation. Herein, we performed ribonucleic acid sequencing of flow-sorted primitive (CD34+CD38low) and progenitor (CD34+ CD38+) chronic phase CML cells, and identified transcriptional upregulation of 32 cell surface molecules relative to corresponding normal bone marrow cells. Focusing on novel markers with increased expression on primitive CML cells, we confirmed upregulation of the scavenger receptor CD36 and the leptin receptor by flow cytometry. We also delineate a subpopulation of primitive CML cells expressing CD36 that is less sensitive to imatinib treatment. Using CD36 targeting antibodies, we show that the CD36 positive cells can be targeted and killed by antibody-dependent cellular cytotoxicity. In summary, CD36 defines a subpopulation of primitive CML cells with decreased imatinib sensitivity that can be effectively targeted and killed using an anti-CD36 antibody.
Assuntos
Citotoxicidade Celular Dependente de Anticorpos , Antígenos CD36/genética , Mesilato de Imatinib/farmacologia , Leucemia Mieloide de Fase Crônica/imunologia , Anticorpos Antineoplásicos/uso terapêutico , Antígenos de Neoplasias/imunologia , Antígenos CD36/imunologia , Humanos , Mesilato de Imatinib/uso terapêutico , Leucemia Mieloide de Fase Crônica/tratamento farmacológico , Leucemia Mieloide de Fase Crônica/patologia , Análise de Sequência de RNA , Células Tumorais Cultivadas , Regulação para CimaRESUMO
Several attempts have been made to model chronic myeloid leukemia (CML) in a xenograft setting but expansion of human myeloid cells in immunodeficient mice has proven difficult to achieve. Lack of cross-reacting cytokines in the microenvironment of the mice has been proposed as a potential reason. In this study we have used NOD/SCID IL2-receptor gamma deficient mice expressing human SCF, IL-3 and GM-CSF (NSGS mice), that should be superior in supporting human, and particularly, myeloid cell engraftment, to expand BCR-ABL1 expressing human cells in order to model CML. NSGS mice transplanted with BCR-ABL1 expressing cells became anemic and had to be sacrificed due to illness, however, this was not accompanied by an expansion of human myeloid cells but rather we observed a massive expansion of human T-cells and macrophages/histiocytes. Importantly, control human cells without BCR-ABL1 expression elicited a similar reaction, although with a slight delay of disease induction, suggesting that while BCR-ABL1 contributes to the inflammatory reaction, the presence of normal human hematopoietic cells is detrimental for NSGS mice.
Assuntos
Citocinas/genética , Sangue Fetal/citologia , Proteínas de Fusão bcr-abl/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , Animais , Modelos Animais de Doenças , Feminino , Sangue Fetal/transplante , Expressão Gênica , Fator Estimulador de Colônias de Granulócitos e Macrófagos/genética , Humanos , Interleucina-3/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Masculino , Camundongos Endogâmicos NOD , Camundongos SCID , Camundongos Transgênicos , Transdução Genética , Transplante HeterólogoRESUMO
OBJECTIVES: Translocations involving the fibroblast growth factor receptor 1 (FGFR1) gene are associated with the 8p11 myeloproliferative syndrome (EMS), a rare neoplasm that following a usually short chronic phase progresses into acute myeloid or lymphoid leukemia. The treatment commonly involves chemotherapy and, if possible, allogeneic stem cell transplantation which is the only therapeutic option for long-term survival. Given the aggressive course of EMS, we here evaluated tyrosine kinase inhibitors as treatment options to delay disease progression. METHODS: We described a new case of EMS and used chromosome analyses, PCR, and sequencing to investigate the underlying genetic aberrations. The sensitivity to several tyrosine kinase inhibitors was tested in vitro on the EMS cell line KG1 and on primary cells from the newly diagnosed EMS patient. RESULTS: A translocation involving chromosomes 8 and 22 was detected, and a BCR/FGFR1 fusion gene was confirmed and characterized by sequencing. KG1 cells and primary EMS cells displayed distinct sensitivity to dovitinib, ponatinib, and dasatinib as compared to normal bone marrow control cells. CONCLUSIONS: These results suggest that treatment with tyrosine kinase inhibitors may be beneficial for patients with EMS during the search for a suitable stem cell donor and for those not eligible for transplantation.
Assuntos
Benzimidazóis/farmacologia , Cromossomos Humanos Par 8 , Dasatinibe/farmacologia , Imidazóis/farmacologia , Transtornos Mieloproliferativos/genética , Proteínas Proto-Oncogênicas c-bcr/genética , Piridazinas/farmacologia , Quinolonas/farmacologia , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/genética , Translocação Genética , Humanos , Concentração Inibidora 50 , Masculino , Transtornos Mieloproliferativos/diagnóstico , Inibidores de Proteínas Quinases/farmacologia , Análise de Sequência de DNA , Células Tumorais Cultivadas , Adulto JovemRESUMO
Chronic myeloid leukemia (CML) is currently treated with tyrosine kinase inhibitors, but these do not effectively eliminate the CML stem cells. As a consequence, CML stem cells persist and cause relapse in most patients upon drug discontinuation. Furthermore, no effective therapy exists for the advanced stages of the disease. Interleukin-1 receptor accessory protein (IL1RAP; IL1R3) is a coreceptor of interleukin-1 receptor type 1 and has been found upregulated on CML stem cells. Here, we show that primitive (CD34+CD38-) CML cells, in contrast to corresponding normal cells, express a functional interleukin-1 (IL-1) receptor complex and respond with NF-κB activation and marked proliferation in response to IL-1. IL1RAP antibodies that inhibit IL-1 signaling could block these effects. In vivo administration of IL1RAP antibodies in mice transplanted with chronic and blast phase CML cells resulted in therapeutic effects mediated by murine effector cells. These results provide novel insights into the role of IL1RAP in CML and a strong rationale for the development of an IL1RAP antibody therapy to target residual CML stem cells.
Assuntos
Anticorpos Antineoplásicos/farmacologia , Proteína Acessória do Receptor de Interleucina-1/antagonistas & inibidores , Interleucina-1/metabolismo , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Proteínas de Neoplasias , Células-Tronco Neoplásicas/metabolismo , Animais , Feminino , Humanos , Proteína Acessória do Receptor de Interleucina-1/metabolismo , Leucemia Mielogênica Crônica BCR-ABL Positiva/metabolismo , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , Masculino , Camundongos , Camundongos Knockout , Proteínas de Neoplasias/antagonistas & inibidores , Proteínas de Neoplasias/metabolismo , Células-Tronco Neoplásicas/patologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Acute myeloid leukemia (AML) is associated with a poor survival rate, and there is an urgent need for novel and more efficient therapies, ideally targeting AML stem cells that are essential for maintaining the disease. The interleukin 1 receptor accessory protein (IL1RAP; IL1R3) is expressed on candidate leukemic stem cells in the majority of AML patients, but not on normal hematopoietic stem cells. We show here that monoclonal antibodies targeting IL1RAP have strong antileukemic effects in xenograft models of human AML. We demonstrate that effector-cell-mediated killing is essential for the observed therapeutic effects and that natural killer cells constitute a critical human effector cell type. Because IL-1 signaling is important for the growth of AML cells, we generated an IL1RAP-targeting antibody capable of blocking IL-1 signaling and show that this antibody suppresses the proliferation of primary human AML cells. Hence, IL1RAP can be efficiently targeted with an anti-IL1RAP antibody capable of both achieving antibody-dependent cellular cytotoxicity and blocking of IL-1 signaling as modes of action. Collectively, these results provide important evidence in support of IL1RAP as a target for antibody-based treatment of AML.
Assuntos
Anticorpos Monoclonais/uso terapêutico , Proteína Acessória do Receptor de Interleucina-1/antagonistas & inibidores , Leucemia Mieloide Aguda/tratamento farmacológico , Proteínas de Neoplasias/antagonistas & inibidores , Animais , Citotoxicidade Celular Dependente de Anticorpos , Divisão Celular , Linhagem Celular Tumoral , Citotoxicidade Imunológica , Humanos , Interleucina-1/antagonistas & inibidores , Proteína Acessória do Receptor de Interleucina-1/imunologia , Células Matadoras Naturais/imunologia , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Proteínas de Neoplasias/imunologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
IL1RAP, a co-receptor for interleukin (IL)-1 and IL-33 receptors, was previously found to be highly upregulated on candidate chronic myeloid leukemia stem cells, allowing for leukemia-selective killing using IL1RAP-targeting antibodies. We analyzed IL1RAP expression in a consecutive series of 29 patients with acute myeloid leukemia (AML) and, based on the level of expression in mononuclear cells (MNCs), we divided the samples into 3 groups: IL1RAP low (n = 6), IL1RAP intermediate (n = 11), and IL1RAP high (n = 12). Within the CD34+CD38- population, the intermediate and high groups expressed higher levels of IL1RAP than did corresponding normal cells. With the aim to target AML stem cells, an anti-IL1RAP monoclonal antibody was generated followed by isotype switching for improved antibody-dependent, cell-mediated cytotoxicity activity. Using this antibody, we achieved selective killing of AML MNC, CD34+CD38+, and CD34+CD38- cells. Our findings demonstrate that IL1RAP is a promising new therapeutic target in AML.
Assuntos
Anticorpos/farmacologia , Citotoxicidade Imunológica/efeitos dos fármacos , Proteína Acessória do Receptor de Interleucina-1/imunologia , Leucemia Mieloide Aguda/patologia , Células-Tronco Neoplásicas/efeitos dos fármacos , Células-Tronco Neoplásicas/imunologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Especificidade de Anticorpos , Células Cultivadas , Feminino , Humanos , Imunoterapia/métodos , Proteína Acessória do Receptor de Interleucina-1/antagonistas & inibidores , Masculino , Pessoa de Meia-Idade , Terapia de Alvo Molecular , Células-Tronco Neoplásicas/patologiaRESUMO
Chronic myeloid leukemia (CML) is genetically characterized by the Philadelphia (Ph) chromosome, formed through a reciprocal translocation between chromosomes 9 and 22 and giving rise to the constitutively active tyrosine kinase P210 BCR/ABL1. Therapeutic strategies aiming for a cure of CML will require full eradication of Ph chromosome-positive (Ph(+)) CML stem cells. Here we used gene-expression profiling to identify IL-1 receptor accessory protein (IL1RAP) as up-regulated in CML CD34(+) cells and also in cord blood CD34(+) cells as a consequence of retroviral BCR/ABL1 expression. To test whether IL1RAP expression distinguishes normal (Ph(-)) and leukemic (Ph(+)) cells within the CML CD34(+)CD38(-) cell compartment, we established a unique protocol for conducting FISH on small numbers of sorted cells. By using this method, we sorted cells directly into drops on slides to investigate their Ph-chromosome status. Interestingly, we found that the CML CD34(+)CD38(-)IL1RAP(+) cells were Ph(+), whereas CML CD34(+)CD38(-)IL1RAP(-) cells were almost exclusively Ph(-). By performing long-term culture-initiating cell assays on the two cell populations, we found that Ph(+) and Ph(-) candidate CML stem cells could be prospectively separated. In addition, by generating an anti-IL1RAP antibody, we provide proof of concept that IL1RAP can be used as a target on CML CD34(+)CD38(-) cells to induce antibody-dependent cell-mediated cytotoxicity. This study thus identifies IL1RAP as a unique cell surface biomarker distinguishing Ph(+) from Ph(-) candidate CML stem cells and opens up a previously unexplored avenue for therapy of CML.
Assuntos
Anticorpos/imunologia , Apoptose , Proteína Acessória do Receptor de Interleucina-1/metabolismo , Leucemia Mielogênica Crônica BCR-ABL Positiva/imunologia , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , Células-Tronco Neoplásicas/metabolismo , ADP-Ribosil Ciclase 1/imunologia , Antígenos CD34/imunologia , Separação Celular , Proteínas de Fusão bcr-abl/metabolismo , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Humanos , Proteína Acessória do Receptor de Interleucina-1/imunologia , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Glicoproteínas de Membrana/imunologia , Células-Tronco Neoplásicas/citologia , Células-Tronco Neoplásicas/imunologiaRESUMO
The 8p11 myeloproliferative syndrome (EMS), also referred to as stem cell leukemia/lymphoma, is a chronic myeloproliferative disorder that rapidly progresses into acute leukemia. Molecularly, EMS is characterized by fusion of various partner genes to the FGFR1 gene, resulting in constitutive activation of the tyrosine kinases in FGFR1. To date, no previous study has addressed the functional consequences of ectopic FGFR1 expression in the potentially most relevant cellular context, that of normal primary human hematopoietic cells. Herein, we report that expression of ZMYM2/FGFR1 (previously known as ZNF198/FGFR1) or BCR/FGFR1 in normal human CD34(+) cells from umbilical-cord blood leads to increased cellular proliferation and differentiation toward the erythroid lineage in vitro. In immunodeficient mice, expression of ZMYM2/FGFR1 or BCR/FGFR1 in human cells induces several features of human EMS, including expansion of several myeloid cell lineages and accumulation of blasts in bone marrow. Moreover, bone marrow fibrosis together with increased extramedullary hematopoiesis is observed. This study suggests that FGFR1 fusion oncogenes, by themselves, are capable of initiating an EMS-like disorder, and provides the first humanized model of a myeloproliferative disorder transforming into acute leukemia in mice. The established in vivo EMS model should provide a valuable tool for future studies of this disorder.
Assuntos
Cromossomos Humanos Par 8 , Modelos Animais de Doenças , Transtornos Mieloproliferativos/genética , Animais , Proteínas de Ligação a DNA/genética , Humanos , Camundongos , Camundongos SCID , Camundongos Transgênicos , Transtornos Mieloproliferativos/patologia , Proteínas de Fusão Oncogênica , Mielofibrose Primária , Proteínas Proto-Oncogênicas c-bcr/genética , Receptor Tipo 1 de Fator de Crescimento de Fibroblastos/genética , Fatores de Transcrição/genéticaRESUMO
OBJECTIVE: The P190 and P210 BCR/ABL1 fusion genes are mainly associated with different types of hematologic malignancies, but it is presently unclear whether they are functionally different following expression in primitive human hematopoietic cells. MATERIALS AND METHODS: We investigated and systematically compared the effects of retroviral P190 BCR/ABL1 and P210 BCR/ABL1 expression on cell proliferation, differentiation, and global gene expression in human CD34(+) cells from cord blood. RESULTS: Expression of either P190 BCR/ABL1 or P210 BCR/ABL1 resulted in expansion of erythroid cells and stimulated erythropoietin-independent burst-forming unit-erythroid colony formation. By using a lentiviral anti-signal transducer and activator of transcription 5 (STAT5) short-hairpin RNA, we found that both P190 BCR/ABL1- and P210 BCR/ABL1-induced erythroid cell expansion were STAT5-dependent. Under in vitro conditions favoring B-cell differentiation, neither P190 nor P210 BCR/ABL1-expressing cells formed detectable levels of CD19-positive cells. Gene expression profiling revealed that P190 BCR/ABL1 and P210 BCR/ABL1 induced almost identical gene expression profiles. CONCLUSIONS: Our data suggest that the early cellular and transcriptional effects of P190 BCR/ABL1 and P210 BCR/ABL1 expression are very similar when they are expressed in the same human progenitor cell population, and that STAT5 is an important regulator of BCR/ABL1-induced erythroid cell expansion.
Assuntos
Antígenos CD34 , Células Eritroides/citologia , Proteínas de Fusão bcr-abl/fisiologia , Células-Tronco Hematopoéticas/citologia , Fator de Transcrição STAT5/fisiologia , Diferenciação Celular , Linhagem da Célula , Proliferação de Células , Sangue Fetal/citologia , Proteínas de Fusão bcr-abl/genética , Perfilação da Expressão Gênica , Humanos , Transdução GenéticaRESUMO
The 8p11 myeloproliferative syndrome (EMS) is a chronic myeloproliferative disorder molecularly characterized by fusion of various 5' partner genes to the 3' part of the fibroblast growth factor receptor 1 (FGFR1) gene at 8p, resulting in constitutive activation of the tyrosine kinase activity contained within FGFR1. EMS is associated with a high risk of transformation to acute myeloid leukemia (AML), but the mechanisms underlying the disease progression are unknown. In the present study, we have investigated a case of EMS harboring a t(8;22)(p11;q11)/BCR-FGFR1 rearrangement as well as a t(9;21)(q34;q22) at the time of AML transformation. FISH and RT-PCR analyses revealed that the t(9;21) leads to a fusion gene consisting of the 5' part of RUNX1 (exons 1-4) fused to repetitive sequences of a gene with unknown function on chromosome 9, adding 70 amino acids to RUNX1 exon 4. The t(9;21) hence results in a truncation of RUNX1. No point mutations were found in the other RUNX1 allele. The most likely functional outcome of the rearrangement was haploinsufficiency of RUNX1, which thus may be one mechanism by which EMS transforms to AML.
Assuntos
Cromossomos Humanos Par 8 , Subunidade alfa 2 de Fator de Ligação ao Core/genética , Fusão Gênica , Transtornos Mieloproliferativos/genética , Idoso , Sequência de Aminoácidos , Sequência de Bases , Northern Blotting , Southern Blotting , DNA Complementar , Progressão da Doença , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Dados de Sequência Molecular , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
HAMLET (human alpha-lactalbumin made lethal to tumor cells) is a protein-lipid complex that induces apoptosis-like death in tumor cells, but leaves fully differentiated cells unaffected. This review summarizes the information on the in vivo effects of HAMLET in patients and tumor models on the tumor cell biology, and on the molecular characteristics of the complex. HAMLET limits the progression of human glioblastomas in a xenograft model and removes skin papillomas in patients. This broad anti-tumor activity includes >40 different lymphomas and carcinomas and apoptosis is independent of p53 or bcl-2. In tumor cells HAMLET enters the cytoplasm, translocates to the perinuclear area, and enters the nuclei where it accumulates. HAMLET binds strongly to histones and disrupts the chromatin organization. In the cytoplasm, HAMLET targets ribosomes and activates caspases. The formation of HAMLET relies on the propensity of alpha-lactalbumin to alter its conformation when the strongly bound Ca2+ ion is released and the protein adopts the apo-conformation that exposes a new fatty acid binding site. Oleic acid (C18:1,9 cis) fits this site with high specificity, and stabilizes the altered protein conformation. The results illustrate how protein folding variants may be beneficial, and how their formation in peripheral tissues may depend on the folding change and the availability of the lipid cofactor. One example is the acid pH in the stomach of the breast-fed child that promotes the formation of HAMLET. This mechanism may contribute to the protective effect of breastfeeding against childhood tumors. We propose that HAMLET should be explored as a novel approach to tumor therapy.