Project description:This SuperSeries is composed of the following subset Series: GSE27512: Identification of a Potently Oncogenic CALM-AF10 Minimal-Fusion Mutant (miRNA) GSE27513: Identification of a Potently Oncogenic CALM-AF10 Minimal-Fusion Mutant (mRNA) Refer to individual Series
Project description:The t(10;11) p (13;q14) translocation, giving rise to CALM-AF10, is a recurring chromosomal translocation observed in several types of acute leukemias as well as in lymphoma. We have previously demonstrated that the expression of the human CALM/AF10 fusion gene in murine bone marrow stem and progenitor cells results in an aggressive acute myeloid leukemia in vivo. In this study, we have screened the various domains essential for CALM-AF10 function and leukemogenicity. Our study identifies a mutant of CALM-AF10 that greatly enhances the clonogenic potential of hematopoietic progenitors while retaining key characteristics of disease induced by the full length CALM-AF10 fusion.
Project description:The t(10;11) p (13;q14) translocation, giving rise to CALM-AF10, is a recurring chromosomal translocation observed in several types of acute leukemias as well as in lymphoma. We have previously demonstrated that the expression of the human CALM/AF10 fusion gene in murine bone marrow stem and progenitor cells results in an aggressive acute myeloid leukemia in vivo. In this study, we have screened the various domains essential for CALM-AF10 function and leukemogenicity. Our study identifies a mutant of CALM-AF10 that greatly enhances the clonogenic potential of hematopoietic progenitors while retaining key characteristics of disease induced by the full length CALM-AF10 fusion.
Project description:The t(10;11) p (13;q14) translocation, giving rise to CALM-AF10, is a recurring chromosomal translocation observed in several types of acute leukemias as well as in lymphoma. We have previously demonstrated that the expression of the human CALM/AF10 fusion gene in murine bone marrow stem and progenitor cells results in an aggressive acute myeloid leukemia in vivo. In this study, we have screened the various domains essential for CALM-AF10 function and leukemogenicity. Our study identifies a mutant of CALM-AF10 that greatly enhances the clonogenic potential of hematopoietic progenitors while retaining key characteristics of disease induced by the full length CALM-AF10 fusion. Global micro-RNA expression of bone marrow cells transduced with various constructs were compared. We used the empty vector, MIG, as a control and baseline. Four samples are tested with three biological replicates each.
Project description:The t(10;11) p (13;q14) translocation, giving rise to CALM-AF10, is a recurring chromosomal translocation observed in several types of acute leukemias as well as in lymphoma. We have previously demonstrated that the expression of the human CALM/AF10 fusion gene in murine bone marrow stem and progenitor cells results in an aggressive acute myeloid leukemia in vivo. In this study, we have screened the various domains essential for CALM-AF10 function and leukemogenicity. Our study identifies a mutant of CALM-AF10 that greatly enhances the clonogenic potential of hematopoietic progenitors while retaining key characteristics of disease induced by the full length CALM-AF10 fusion. Global gene expression of bone marrow cells transduced with various constructs were compared. We used the empty vector, MIG, as a control and baseline. Four samples are tested with three biological replicates each.
Project description:Chromosomal translocations are important genetic perturbations frequently associated with hematologic malignancies; characterization of these events has been a rich source of insights into the mechanisms that lead to malignant transformation. The t(10;11)(p13;q14-21) results in a recently identified rare but recurring chromosomal translocation seen in patients with ALL as well as AML, and results in the production of a CALM-AF10 fusion gene. Although the details by which the CALM-AF10 fusion protein exerts its leukemogenic effect remain unclear, emerging data suggests that the CALM-AF10 fusion impairs differentiation of hematopoietic cells, at least in part via an upregulation of HOXA cluster genes. This review discusses the normal structure and function of CALM and AF10, describes the spectrum of clinical findings seen in patients with CALM-AF10 fusions, summarizes recently published CALM-AF10 mouse models and highlights the role of HOXA cluster gene activation in CALM-AF10 leukemia.
Project description:A subset of acute myeloid and lymphoid leukemia cases harbor a t(10;11)(p13;q14) translocation resulting in the CALM-AF10 fusion gene. Standard chemotherapeutic strategies are often ineffective in treating patients with CALM-AF10 fusions. Hence, there is an urgent need to identify molecular pathways dysregulated in CALM-AF10-positive leukemias which may lay the foundation for novel targeted therapies. Here we demonstrate that the Polycomb Repressive Complex 1 gene BMI1 is consistently overexpressed in adult and pediatric CALM-AF10-positive leukemias. We demonstrate that genetic Bmi1 depletion abrogates CALM-AF10-mediated transformation of murine hematopoietic stem and progenitor cells (HSPCs). Furthermore, CALM-AF10-positive murine and human AML cells are sensitive to the small-molecule BMI1 inhibitor PTC-209 as well as to PTC-596, a compound in clinical development that has been shown to result in downstream degradation of BMI1 protein. PTC-596 significantly prolongs survival of mice injected with a human CALM-AF10 cell line in a xenograft assay. In summary, these results validate BMI1 as a bona fide candidate for therapeutic targeting in AML with CALM-AF10 rearrangements.
Project description:The CATS protein was recently identified as a novel CALM interacting protein. CATS increases the nuclear and specifically the nucleolar localization of the leukemogenic CALM/AF10 fusion protein. We cloned and characterized the murine Cats gene. Detailed analysis of murine Cats expression during mouse embryogenesis showed an association with rapidly proliferating tissues. Interestingly, the Cats transcript is highly expressed in murine hematopoietic cells transformed by CALM/AF10. The CATS protein is highly expressed in leukemia, lymphoma and tumor cell lines but not in non-proliferating T-cells or human peripheral blood lymphocytes. CATS protein levels are cell cycle dependent and it is induced by mitogens, suggesting a role of CATS in the control of cell proliferation and possibly CALM/AF10-mediated leukemogenesis.
Project description:Iron, an essential nutrient for cellular growth and proliferation, enters cells via clathrin-mediated endocytosis. The clathrin assembly lymphoid myeloid (CALM) protein plays an essential role in the cellular import of iron by clathrin-mediated endocytosis. CALM-AF10 leukemias harbor a single copy of the normal CALM gene and therefore may be more sensitive to the growth-inhibitory effect of iron restriction compared with normal hematopoietic cells. We found that CALM heterozygous (CALM(HET)) murine fibroblasts exhibit signs of iron deficiency, with increased surface transferrin receptor levels and reduced growth rates. CALM(HET) hematopoietic cells are more sensitive in vitro to iron chelators than their wild type counterparts. Iron chelation also displayed toxicity toward cultured CALM(HET)CALM-AF10 leukemia cells, and this effect was additive to that of chemotherapy. In mice transplanted with CALM(HET)CALM-AF10 leukemia, we found that dietary iron restriction reduced tumor burden in the spleen. However, dietary iron restriction, used alone or in conjunction with chemotherapy, did not increase survival of mice with CALM(HET)CALM-AF10 leukemia. In summary, although CALM heterozygosity results in iron deficiency and increased sensitivity to iron chelation in vitro, our data in mice do not suggest that iron depletion strategies would be beneficial for the therapy of CALM-AF10 leukemia patients.
Project description:The t(10;11) chromosomal translocation gives rise to the CALM-AF10 fusion gene and is found in patients with aggressive and difficult-to-treat hematopoietic malignancies. CALM-AF10-driven leukemias are characterized by HOXA gene up-regulation and a global reduction in H3K79 methylation. DOT1L, the H3K79 methyltransferase, interacts with the octapeptide/leucine zipper domain of AF10, and this region has been shown to be necessary and sufficient for CALM-AF10-mediated transformation. However, the precise role of CALM in leukemogenesis remains unclear. Here, we show that CALM contains a nuclear export signal (NES) that mediates cytoplasmic localization of CALM-AF10 and is necessary for CALM-AF10-dependent transformation. Fusions of the CALM NES (NES(CALM)-AF10) or NES motifs from heterologous proteins (ABL1, Rev, PKIA, APC) in-frame with AF10 are sufficient to immortalize murine hematopoietic progenitors in vitro. The CALM NES is essential for CALM-AF10-dependent Hoxa gene up-regulation and aberrant H3K79 methylation, possibly by mislocalization of DOT1L. Finally, we observed that CALM-AF10 leukemia cells are selectively sensitive to inhibition of nuclear export by Leptomycin B. These findings uncover a novel mechanism of leukemogenesis mediated by the nuclear export pathway and support further investigation of the utility of nuclear export inhibitors as therapeutic agents for patients with CALM-AF10 leukemias.