ABSTRACT
Spi-1 Proto-Oncogene (SPI1) fusion genes are recurrently found in T-cell acute lymphoblastic leukemia (T-ALL) cases but are insufficient to drive leukemogenesis. Here we show that SPI1 fusions in combination with activating NRAS mutations drive an immature T-ALL in vivo using a conditional bone marrow transplant mouse model. Addition of the oncogenic fusion to the NRAS mutation also results in a higher leukemic stem cell frequency. Mechanistically, genetic deletion of the ß-catenin binding domain within Transcription factor 7 (TCF7)-SPI1 or use of a TCF/ß-catenin interaction antagonist abolishes the oncogenic activity of the fusion. Targeting the TCF7-SPI1 fusion in vivo with a doxycycline-inducible knockdown results in increased differentiation. Moreover, both pharmacological and genetic inhibition lead to down-regulation of SPI1 targets. Together, our results reveal an example where TCF7-SPI1 leukemia is vulnerable to pharmacological targeting of the TCF/ß-catenin interaction.
Subject(s)
GTP Phosphohydrolases/metabolism , Membrane Proteins/metabolism , Precursor T-Cell Lymphoblastic Leukemia-Lymphoma/metabolism , Proto-Oncogene Proteins/metabolism , T Cell Transcription Factor 1/metabolism , Trans-Activators/metabolism , beta Catenin/metabolism , Animals , Bone Marrow Transplantation , Carcinogenesis/genetics , Disease Models, Animal , Female , GTP Phosphohydrolases/genetics , HEK293 Cells , Humans , Membrane Proteins/genetics , Mice , Mice, Inbred C57BL , Mutation , Oncogene Proteins, Fusion/genetics , Oncogene Proteins, Fusion/metabolism , Oncogenes , Precursor T-Cell Lymphoblastic Leukemia-Lymphoma/genetics , Proto-Oncogene Mas , Proto-Oncogene Proteins/genetics , T Cell Transcription Factor 1/genetics , T-Lymphocytes/metabolism , Trans-Activators/genetics , Transcriptome , beta Catenin/geneticsSubject(s)
Cadherins/metabolism , Gene Expression Regulation, Leukemic , Mutation , Precursor T-Cell Lymphoblastic Leukemia-Lymphoma/pathology , Receptor, Notch1/genetics , T-Lymphocytes/pathology , Cadherins/genetics , Humans , Precursor T-Cell Lymphoblastic Leukemia-Lymphoma/genetics , Precursor T-Cell Lymphoblastic Leukemia-Lymphoma/metabolism , Protein Isoforms , T-Lymphocytes/metabolism , Tumor Cells, CulturedABSTRACT
Leukemia is caused by the accumulation of multiple genomic lesions in hematopoietic precursor cells. However, how these events cooperate during oncogenic transformation remains poorly understood. We studied the cooperation between activated JAK3/STAT5 signaling and HOXA9 overexpression, two events identified as significantly co-occurring in T-cell acute lymphoblastic leukemia. Expression of mutant JAK3 and HOXA9 led to a rapid development of leukemia originating from multipotent or lymphoid-committed progenitors, with a significant decrease in disease latency compared with JAK3 or HOXA9 alone. Integrated RNA sequencing, chromatin immunoprecipitation sequencing, and Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) revealed that STAT5 and HOXA9 have co-occupancy across the genome, resulting in enhanced STAT5 transcriptional activity and ectopic activation of FOS/JUN (AP1). Our data suggest that oncogenic transcription factors such as HOXA9 provide a fertile ground for specific signaling pathways to thrive, explaining why JAK/STAT pathway mutations accumulate in HOXA9-expressing cells.Significance: The mechanism of oncogene cooperation in cancer development remains poorly characterized. In this study, we model the cooperation between activated JAK/STAT signaling and ectopic HOXA9 expression during T-cell leukemia development. We identify a direct cooperation between STAT5 and HOXA9 at the transcriptional level and identify PIM1 kinase as a possible drug target in mutant JAK/STAT/HOXA9-positive leukemia cases. Cancer Discov; 8(5); 616-31. ©2018 AACR.This article is highlighted in the In This Issue feature, p. 517.
Subject(s)
Cell Transformation, Neoplastic/metabolism , Homeodomain Proteins/metabolism , Janus Kinases/metabolism , Leukemia/etiology , Leukemia/metabolism , STAT Transcription Factors/metabolism , Signal Transduction , Animals , Bone Marrow Transplantation , Chromatin Assembly and Disassembly , Disease Models, Animal , Gene Expression , Hematopoietic Stem Cells/metabolism , Homeodomain Proteins/genetics , Humans , Janus Kinase 3/genetics , Janus Kinase 3/metabolism , Janus Kinases/genetics , Male , Mice , Mutation , Precursor T-Cell Lymphoblastic Leukemia-Lymphoma/etiology , Precursor T-Cell Lymphoblastic Leukemia-Lymphoma/metabolism , Protein Binding , STAT Transcription Factors/genetics , Transcription Factor AP-1/metabolism , Transduction, Genetic , TransgenesABSTRACT
FLT3 and PDGFR tyrosine kinases are important targets for therapy of different types of leukemia. Several FLT3/PDGFR inhibitors are currently under clinical investigation for combination with standard therapy for treatment of acute myeloid leukemia (AML), however these agents only induce partial remission and development of resistance has been reported. In this work we describe the identification of potent and novel dual FLT3/PDGFR inhibitors that resulted from our efforts to screen a library of 25,607 small molecules against the FLT3 dependent cell line MOLM-13 and the PDGFR dependent cell line EOL-1. This effort led to the identification of five compounds that were confirmed to be active on additional FLT3 dependent cell lines (cellular EC50 values between 35 and 700 nM), while having no significant effect on 24 other tyrosine kinases.
Subject(s)
Protein Kinase Inhibitors/pharmacology , Receptor, Platelet-Derived Growth Factor alpha/antagonists & inhibitors , Receptor, Platelet-Derived Growth Factor beta/antagonists & inhibitors , Small Molecule Libraries/pharmacology , fms-Like Tyrosine Kinase 3/antagonists & inhibitors , Blotting, Western , Cell Line, Tumor , Cell Proliferation/drug effects , Cell Survival/drug effects , Dose-Response Relationship, Drug , Drug Screening Assays, Antitumor , Humans , Hypereosinophilic Syndrome/metabolism , Hypereosinophilic Syndrome/pathology , Leukemia, Monocytic, Acute/metabolism , Leukemia, Monocytic, Acute/pathology , Molecular Structure , Phosphorylation/drug effects , Protein Kinase Inhibitors/chemistry , Receptor, Platelet-Derived Growth Factor alpha/metabolism , Receptor, Platelet-Derived Growth Factor beta/metabolism , Small Molecule Libraries/chemistry , Structure-Activity Relationship , fms-Like Tyrosine Kinase 3/metabolismABSTRACT
T-cell acute lymphoblastic leukemia (T-ALL) is caused by the cooperation of multiple oncogenic lesions. We used exome sequencing on 67 T-ALLs to gain insight into the mutational spectrum in these leukemias. We detected protein-altering mutations in 508 genes, with an average of 8.2 mutations in pediatric and 21.0 mutations in adult T-ALL. Using stringent filtering, we predict seven new oncogenic driver genes in T-ALL. We identify CNOT3 as a tumor suppressor mutated in 7 of 89 (7.9%) adult T-ALLs, and its knockdown causes tumors in a sensitized Drosophila melanogaster model. In addition, we identify mutations affecting the ribosomal proteins RPL5 and RPL10 in 12 of 122 (9.8%) pediatric T-ALLs, with recurrent alterations of Arg98 in RPL10. Yeast and lymphoid cells expressing the RPL10 Arg98Ser mutant showed a ribosome biogenesis defect. Our data provide insights into the mutational landscape of pediatric versus adult T-ALL and identify the ribosome as a potential oncogenic factor.
