Project description:Acute megakaryoblastic leukemia (AMKL) is a heterogeneous disease generally associated with poor prognosis. Gene expression profiles indicate the existence of distinct molecular subgroups and several genetic alterations have been characterized in the past years, including the t(1;22)(p13;q13) and the trisomy 21 associated with GATA1 mutations. However, the majority of patients do not present with known mutations and the limited access to primary patient leukemic cells also prevents efficient development of novel therapeutic strategies. Using a xenotransplantation approach, we have modeled human pediatric AMKL in immunodeficient mice. High-throughput sequencing of engrafted cases identified recurrent fusions genes that define new molecular subgroups. A group of patients present with MLL or NUP98 fusion genes leading to upregulation of the HOX A cluster genes as described in other subtypes of AML. Also, a novel CBFA2T3-GLIS2 fusion gene resulting from a cytogenetically invisible inversion of chromosome 16 was identified and observed in 31% of non Down syndrome AMKL. These data provide new markers that will be useful for the diagnosis and follow-up of patients. Finally, we show that AMKL xenograft models constitute a relevant preclinical screening platform to validate the efficacy of novel therapies such as dimethylfasudil, a novel small molecule ploidy inducer.
Project description:We engineered human models of CBFA2T3::GLIS2 acute megakaryoblastic leukemia and compared gene expression profiles to primary pediatric samples.
Project description:Acute megakaryoblastic leukemia (AMKL) is a heterogeneous disease generally associated with poor prognosis. Gene expression profiles indicate the existence of distinct molecular subgroups, and several genetic alterations have been characterized in the past years, including the t(1;22)(p13;q13) and the trisomy 21 associated with GATA1 mutations. However, the majority of patients do not present known mutations, and the limited access to primary patient leukemic cells impedes the efficient development of novel therapeutic strategies. In this study, using a xenotransplantation approach, we have modeled human pediatric AMKL in immunodeficient mice. Analysis of high-throughput RNA sequencing identified recurrent fusion genes defining new molecular subgroups.
Project description:Alterations of IKZF1, encoding the lymphoid transcription factor IKAROS, are a hallmark of high risk acute lymphoblastic leukemia (ALL), however the role of IKZF1 alterations in ALL pathogenesis is poorly understood. Here we show that in mouse models of BCR-ABL1 leukemia, Ikzf1 and Arf alterations synergistically promote the development of an aggressive lymphoid leukemia. Ikzf1 alterations were associated with acquisition of stem cell-like features, including self-renewal and increased bone marrow stromal adhesion. Rexinoid receptor agonists reversed this phenotype, in part by inducing expression of IKZF1, resulting in abrogation of adhesion and self-renewal, cell cycle arrest and attenuation of proliferation without direct cytotoxicity. Retinoids potentiated the activity of dasatinib in mouse and human BCR-ABL1 ALL, providing a new therapeutic option in IKZF1-mutated ALL. Significance: The outcome of therapy for high-risk acute lymphoblastic leukemia remains suboptimal despite contemporary chemotherapy and the advent of targeted therapeutic approaches. Recent genomic studies have identified deletions or mutations of IKZF1 as a hallmark of high-risk ALL, but an understanding of how IKZF1 alteration contribute to leukemia development are lacking. Here we show that IKZF1 alterations drive lymphoid lineage, a stem cell-like phenotype, abnormal bone marrow adhesion, and poor responsiveness to tyrosine kinase inhibitor (TKI) therapy. Using a high-content screen, we show that retinoids reverse this phenotype in part by inducing expression of wild type IKZF1, and increase responsiveness to TKIs. These findings provide new insight into the pathogenesis of high-risk ALL and potential new therapeutic approaches. Pre-B mRNA profiles of p185 MIG and IK6 cells, DMSO or drug treated, in 3 or 4 replicates, using Illumina HiSeq 2500.
Project description:Acute leukemias represent deadly malignancies which require better treatment. As challenge, treatment is counteracted by a microenvironment protecting dormant leukemia stem cells. To identify responsible surface proteins, we performed deep proteome profiling on minute numbers of dormant patient-derived xenograft (PDX) leukemia stem cells isolated from mice. Candidates were functionally screened by establishing a comprehensive CRISPR-Cas9 pipeline in PDX models in vivo. A disintegrin and metalloproteinase domain-containing protein 10 (ADAM10) was identified as essential vulnerability required for survival and growth of different types of acute leukemias in vivo and reconstitution assays in PDX models proved the relevance of its sheddase activity. Of translational importance, molecular or pharmacological targeting of ADAM10 reduced PDX leukemia burden, cell homing to the murine bone marrow and stem cell frequency, and increased leukemia response to conventional chemotherapy in vivo. These findings identify ADAM10 as attractive therapeutic target for future treatment of acute leukemias.
