RESUMO
B-cell acute lymphoblastic leukemia (B-ALL) occurs most commonly in children, whereas chronic myeloid leukemia is more frequent in adults. The myeloid bias of hematopoiesis in elderly individuals has been considered causative, but the age of the bone marrow microenvironment (BMM) may be contributory. Using various murine models of B-ALL in young vs old mice, we recapitulated B-ALL preponderance in children vs adults. We showed differential effects of young vs old BM macrophages on B-ALL cell function. Molecular profiling using RNA- and ATAC-sequencing revealed pronounced differences in young vs old BMM-derived macrophages and enrichment for gene sets associated with inflammation. In concordance with the role of C-X-C motif chemokine (CXCL) 13 for disease-associated B-cell chemoattraction, we found CXCL13 to be highly expressed in young macrophages on a translational compared with a transcriptional level. Inhibition of CXCL13 in BM macrophages impaired leukemia cell migration and decreased the proliferation of cocultured B-ALL cells, whereas recombinant CXCL13 increased pAKT and B-ALL cell expansion. Pretreatment of B-ALL-initiating cells with CXCL13 accelerated B-ALL progression. Deficiency of Cxcr5, the receptor for CXCL13, on B-ALL-initiating cells prolonged murine survival, whereas high expression of CXCR5 in pediatric B-ALL may predict central nervous system relapse. CXCL13 staining was increased in bone sections from pediatric compared with adult patients with B-ALL. Taken together, our study shows that the age of the BMM and, in particular, BM macrophages influence the leukemia phenotype. The CXCR5-CXCL13 axis may act as prognostic marker and an attractive novel target for the treatment of B-ALL.
Assuntos
Quimiocina CXCL13/genética , Regulação Leucêmica da Expressão Gênica , Leucemia-Linfoma Linfoblástico de Células Precursoras B/genética , Receptores CXCR5/genética , Microambiente Tumoral , Envelhecimento , Animais , Medula Óssea/metabolismo , Medula Óssea/patologia , Linhagem Celular Tumoral , Progressão da Doença , Humanos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Leucemia-Linfoma Linfoblástico de Células Precursoras B/patologiaRESUMO
The endosteal bone marrow niche and vascular endothelial cells provide sanctuaries for leukemic cells. In murine chronic myeloid leukemia (CML) CD44 on leukemia cells and E-selectin on bone marrow endothelium are essential mediators for the engraftment of leukemic stem cells. We hypothesized that non-adhesion of CML-initiating cells to E-selectin on the bone marrow endothelium may lead to superior eradication of leukemic stem cells in CML after treatment with imatinib than imatinib alone. Indeed, here we show that treatment with the E-selectin inhibitor GMI-1271 in combination with imatinib prolongs survival of mice with CML via decreased contact time of leukemia cells with bone marrow endothelium. Non-adhesion of BCR-ABL1+ cells leads to an increase of cell cycle progression and an increase of expression of the hematopoietic transcription factor and proto-oncogene Scl/Tal1 in leukemia-initiating cells. We implicate SCL/TAL1 as an indirect phosphorylation target of BCR-ABL1 and as a negative transcriptional regulator of CD44 expression. We show that increased SCL/TAL1 expression is associated with improved outcome in human CML. These data demonstrate the BCR-ABL1-specific, cell-intrinsic pathways leading to altered interactions with the vascular niche via the modulation of adhesion molecules - which could be exploited therapeutically in the future.
Assuntos
Proteínas de Fusão bcr-abl , Leucemia Mielogênica Crônica BCR-ABL Positiva , Animais , Medula Óssea , Selectina E/genética , Células Endoteliais , Proteínas de Fusão bcr-abl/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/tratamento farmacológico , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Camundongos , Proto-Oncogene Mas , Proteína 1 de Leucemia Linfocítica Aguda de Células TRESUMO
The transcriptional regulator far upstream element binding protein 1 (FUBP1) acts as an oncoprotein in solid tumor entities and plays a role in the maintenance of hematopoietic stem cells. However, its potential function in leukemia is unknown. In murine models of chronic (CML) and acute myeloid leukemia (AML) induced by BCR-ABL1 and MLL-AF9, respectively, knockdown of Fubp1 resulted in prolonged survival, decreased numbers of CML progenitor cells, decreased cell cycle activity and increased apoptosis. Knockdown of FUBP1 in CML and AML cell lines recapitulated these findings and revealed enhanced DNA damage compared to leukemia cells expressing wild type FUBP1 levels. FUBP1 was more highly expressed in human CML compared to normal bone marrow cells and its expression correlated with disease progression. In AML, higher FUBP1 expression in patient leukemia cells was observed with a trend toward correlation with shorter overall survival. Treatment of mice with AML with irinotecan, known to inhibit topoisomerase I and FUBP1, significantly prolonged survival alone or in combination with cytarabine. In summary, our data suggest that FUBP1 acts as cell cycle regulator and apoptosis inhibitor in leukemia. We demonstrated that FUBP1 might play a role in DNA repair, and its inhibition may improve outcome in leukemia patients.
Assuntos
Apoptose , Dano ao DNA , Proteínas de Ligação a DNA/metabolismo , Modelos Animais de Doenças , Leucemia Mielogênica Crônica BCR-ABL Positiva/patologia , Leucemia Mieloide Aguda/patologia , Proteínas de Ligação a RNA/metabolismo , Animais , Transplante de Medula Óssea , Ciclo Celular , Proteínas de Ligação a DNA/antagonistas & inibidores , Proteínas de Ligação a DNA/genética , Humanos , Irinotecano/farmacologia , Leucemia Mielogênica Crônica BCR-ABL Positiva/genética , Leucemia Mielogênica Crônica BCR-ABL Positiva/terapia , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/terapia , Camundongos , Camundongos Endogâmicos C57BL , Proteínas de Ligação a RNA/antagonistas & inibidores , Proteínas de Ligação a RNA/genética , Inibidores da Topoisomerase I/farmacologia , Células Tumorais CultivadasRESUMO
Imaging of the leukemic bone marrow microenvironment, also called the leukemic bone marrow niche, is an essential method to determine and to evaluate the progression of chronic myelogenous leukemia (CML) and other leukemias in murine models. In this chapter we introduce the murine model of CML primarily used in our laboratory by describing blood and bone marrow analysis as well as the method of histological sectioning and immunohistochemistry in combination with various stainings that can help to understand the complex interaction between leukemic cells, their normal hematopoietic counterparts, and the bone marrow microenvironment. We conclude with describing how to image the bone marrow niche using in vivo microscopy.