Project description:Transient abnormal myelopoiesis (TAM) is a clonal pre-leukemic disorder that progresses to myeloid leukemia of Down syndrome (ML-DS) through the accumulation of genetic alterations. To investigate the mechanism of leukemogenesis in this disorder, a xenograft model of TAM was established using NOD/Shi-scid, IL-2Rγnull mice. In serial transplantations, engrafted TAM-derived cells showed the emergence of divergent subclones with another GATA1 mutation and various CNAs, including a 16q deletion and 1q gain, which are clinically associated with ML-DS. These results suggest that genetically heterogeneous subclones with varying leukemia-initiating potential already exist in the neonatal TAM phase, and ML-DS may develop from a pool of such minor clones through clonal selection. Affymetrix SNP arrays were performed according to the manufacturer's directions on DNA extracted from murine bone marrow (hCD45 sorted) or human peripheral blood samples. Copy number analysis of Affymetrix 500K SNP arrays was performed for xenografted TAM samples of 3 patients. There are also 3 samples from TAM patients in remission, which were used as references for copy number inference.
Project description:Transient abnormal myelopoiesis (TAM) is a clonal pre-leukemic disorder that progresses to myeloid leukemia of Down syndrome (ML-DS) through the accumulation of genetic alterations. To investigate the mechanism of leukemogenesis in this disorder, a xenograft model of TAM was established using NOD/Shi-scid, IL-2Rγnull mice. In serial transplantations, engrafted TAM-derived cells showed the emergence of divergent subclones with another GATA1 mutation and various CNAs, including a 16q deletion and 1q gain, which are clinically associated with ML-DS. These results suggest that genetically heterogeneous subclones with varying leukemia-initiating potential already exist in the neonatal TAM phase, and ML-DS may develop from a pool of such minor clones through clonal selection.
Project description:Transient leukemia (TL) is evident in 5-10% of all neonates with Down syndrome (DS) and associated with N-terminal truncating GATA1-mutations (GATA1s). Here we analyzed the effect of on gene expression upon ectopic expression of Gata1s or Gata1, while simultaneously knocking down endogenous GATA1, in wild-type CD34+-hematopoietic stem and progenitor cells during myeloid differentiation. Ectopic expression of Gata1s, but not Gata1, in wild-type CD34+-hematopoietic stem and progenitor cells induced hyperproliferation of eosinophil promyelocytes in vitro. While GATA1s retained the function of GATA1 to induce eosinophil genes by occupying their promoter regions, GATA1s was impaired in its ability to repress oncogenic MYC and the pro-proliferative E2F transcription network.
Project description:Transient leukemia (TL) is evident in 5-10% of all neonates with Down syndrome (DS) and associated with N-terminal truncating GATA1-mutations (GATA1s). Here we analyzed the effect of on gene expression upon ectopic expression of Gata1s or Gata1, while simultaneously knocking down endogenous GATA1, in wild-type CD34+-hematopoietic stem and progenitor cells during myeloid differentiation. Ectopic expression of Gata1s, but not Gata1, in wild-type CD34+-hematopoietic stem and progenitor cells induced hyperproliferation of eosinophil promyelocytes in vitro. While GATA1s retained the function of GATA1 to induce eosinophil genes by occupying their promoter regions, GATA1s was impaired in its ability to repress oncogenic MYC and the pro-proliferative E2F transcription network. We lentivirally transduced wild-type CD34+-hematopoietic stem and progenitor cells to ectopically express Gata1s or Gata1, while simultaneously knocking down endogenous GATA1, and cultured them in myeloid differentiation for 0, 4 and 14 days.