Project description:Interest focuses on genes encoding histone demethylases in hematologic malignancies, such as EZH2 (enhancer of zeste homolog 2). EZH2 mutations were recurrently observed in lymphomas and chronic myeloid malignancies, but data in acute leukemias are limited. We investigated 13 PICALM-MLLT10 (=CALM-AF10) rearranged acute leukemia predominantly of T-lineage (7 m/6 f; 6–53 years) by deep-sequencing for EZH2mut and identified 3 (23%) EZH2mut carriers: one splice site mutation in exon 14, while two patients had missense mutations in the D1 region of exon 5 which interacts with different DNA methyltransferase genes (but no DNMT3Amut was detected in the 13 PICALM-MLLT10-positive patients). In contrast, no EZH2mut was found in an independent cohort of 12 PICALM-MLLT10-negative T-ALL. Gene expression profiling revealed increased expression of genes with a role for transcription or intracellular transport processes in the PICALM-MLLT10-positive cases. The frequent occurrence of EZH2mut in PICALM-MLLT10-positive malignancies emphasizes a cooperative effect in acute leukemias. 29 patients analyzed with gene expression microarrays.
Project description:Interest focuses on genes encoding histone demethylases in hematologic malignancies, such as EZH2 (enhancer of zeste homolog 2). EZH2 mutations were recurrently observed in lymphomas and chronic myeloid malignancies, but data in acute leukemias are limited. We investigated 13 PICALM-MLLT10 (=CALM-AF10) rearranged acute leukemia predominantly of T-lineage (7 m/6 f; 6–53 years) by deep-sequencing for EZH2mut and identified 3 (23%) EZH2mut carriers: one splice site mutation in exon 14, while two patients had missense mutations in the D1 region of exon 5 which interacts with different DNA methyltransferase genes (but no DNMT3Amut was detected in the 13 PICALM-MLLT10-positive patients). In contrast, no EZH2mut was found in an independent cohort of 12 PICALM-MLLT10-negative T-ALL. Gene expression profiling revealed increased expression of genes with a role for transcription or intracellular transport processes in the PICALM-MLLT10-positive cases. The frequent occurrence of EZH2mut in PICALM-MLLT10-positive malignancies emphasizes a cooperative effect in acute leukemias.
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 translocation t(10,11)(p13;q14) resulting in the formation of the CALM/AF10 fusion gene is involved in various hematological malignancies including acute myeloid leukemia, T-cell acute lymphoblastic leukemia, and malignant lymphoma and is usually associated with poor prognosis. We established a knock-in mouse model allowing tissue-specific CALM/AF10 expression from the Rosa26 locus using a loxP-STOP-loxP cassette to study leukemic transformation by the CALM/AF10 fusion protein during hematopoiesis. vav-Cre induced pan-hematopoietic expression of the CALM/AF10 fusion gene led to acute leukemia with a median latency of 12 months. Leukemias were either myeloid or had myeloid feature and showed expression of the B cell marker B220. Gene expression profiling of leukemic bone marrow cells revealed the overexpression of Hoxa cluster genes and the Hox co-factor Meis1. The long latency to leukemia development suggested that additional, collaborative genetic lesions are required. We identified an average of 2 to 3 additional mutations per leukemia using whole-exome sequencing. When CALM/AF10 was expressed in the B lymphoid compartment using mb1-Cre or CD19-Cre inducer lines no leukemia development was observed. Our results indicate that CALM/AF10 needs to be expressed from the stem or early progenitor cell stage onward to permit the acquisition of additional mutations required for leukemic transformation.
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:Background: Wnt signaling maintains the undifferentiated state of intestinal crypt progenitor cells by inducing the formation of nuclear TCF4/beta-catenin complexes. In colorectal cancer, activating mutations in Wnt pathway components cause inappropriate activation of TCF4/beta-catenin -driven transcription. Despite the passage of a decade after the discovery of TCF4 and beta-catenin as the molecular effectors of the Wnt signal, few transcriptional activators essential and unique to the regulation of this transcription program have been found. Methodology/Principal Findings: Using proteomics, we identified the leukemia-associated Mllt10/Af10 and the methyltransferase Dot1l, as Tcf4/beta-catenin interactors in mouse small intestinal crypts. Mllt10/Af10-Dot1l, essential for transcription elongation, are recruited to Wnt target genes in a beta-catenin -dependent manner, resulting in H3K79 methylation over their coding regions in vivo in proliferative crypts of mouse small intestine, in colorectal cancer and Wnt-inducible HEK293T cells. Depletion of MLLT10/AF10 in colorectal cancer and Wnt-inducible HEK293T cells followed by expression array analysis identifies MLLT10/AF10 and DOT1L as essential activators dedicated to Wnt target gene regulation. In contrast, previously published b-catenin coactivators p300 and beta-catenin displayed a more pleiotropic target gene expression profile controlling Wnt and other pathways. tcf4, mllt10/af10 and dot1l are co-expressed in Wnt-driven tissues in zebrafish and essential for Wnt-reporter activity. Intestinal differentiation defects in apc-mutant zebrafish can be rescued by depletion of Mllt10 and Dot1l, establishing these genes as activators downstream of Apc in Wnt target gene activation in vivo. Morpholino-depletion of mllt10/af10-dot1l in zebrafish results in defects in intestinal homeostasis and a significant reduction in the in vivo expression of direct Wnt target genes and in the number of proliferative intestinal epithelial cells. Conclusions/Significance: We conclude that Mllt10/Af10-Dot1l are essential, dedicated activators of Wnt-dependent transcription, critical for maintenance of intestinal proliferation and homeostasis. The methyltransferase Dot1l may present an attractive candidate for drug targeting in colorectal cancer. 6 samples for Ls174T cells: si-b-catenin against si-control and dyeswap of it, si-control, si-MLLT10, si-BRG1 and si-P300 are hybridized against common reference RNA; 6 samples of HEK293T cells: Wnt3A or control medium (CM) induction for 9 hours, si-MLLT10, si-DOT1L, si-BRG1 and si-P300 upon 9 hour Wnt3A induction are all hybridized against common reference RNA