Aberrant splicing is a hallmark of leukemias with mutations in splicing factor (SF)-encoding genes. Here we investigated its prevalence in pediatric B-cell acute lymphoblastic leukemias (B-ALL), where SFs are not mutated. By comparing them to normal pro-B cells, we found thousands of aberrant local splice variations (LSVs) per sample, with 279 LSVs in 241 genes present in every comparison. These genes were enriched in RNA processing pathways and encoded ~100 SFs, e.g. hnRNPA1. hnRNPA1 3'UTR was most pervasively misspliced, yielding the transcript subject to nonsense-mediated decay. Thus, we knocked it down in B-lymphoblastoid cells, identified 213 hnRNPA1-dependent splicing events, and defined the hnRNPA1 splicing signature in pediatric leukemias. One of its elements was DICER1, a known tumor suppressor gene; its LSVs involved the 5' UTR, suggestive of splicing as a mechanism of translational deregulation. Additionally, we searched for LSVs in other leukemia and lymphoma drivers and discovered 81 LSVs in 41 genes. 77 LSVs were confirmed using two large independent B-ALL RNA-seq datasets. In fact, the twenty most common B-ALL drivers showed higher prevalence of aberrant splicing than of somatic mutations. Thus, post-transcriptional deregulation of SF can drive widespread changes in B-ALL splicing and likely contribute to disease pathogenesis. Overall design: We profiled hnRNPA1 Ctrl and hnRNPA1 knockdown with 2 replicates each.
Aberrant splicing in B-cell acute lymphoblastic leukemia.
Specimen part, Cell line, Subject
View SamplesAberrant signal transduction contributes substantially to leukemogenesis. The Janus kinase 1 (JAK1) gene encodes a cytoplasmic tyrosine kinase that noncovalently associates with a variety of cytokine receptors and plays a nonredundant role in lymphoid cell precursor proliferation, survival, and differentiation. Somatic mutations in JAK1 occur in individuals with acute lymphoblastic leukemia (ALL). JAK1 mutations were more prevalent among adult subjects with the T cell precursor ALL, where they accounted for 18% of cases, and were associated with advanced age at diagnosis, poor response to therapy, and overall prognosis
ALL-associated JAK1 mutations confer hypersensitivity to the antiproliferative effect of type I interferon.
Specimen part
View SamplestPTEN-/- mice display a deletion of the PTEN tumor suppressor gene specifically in T cells (cross PTEN flox/flox x lck-Cre). They develop T cell lymphoma with a primary thymic tumor and invasion of most organ at late stage of the disease.
Pharmacological inhibition of carbonic anhydrase XII interferes with cell proliferation and induces cell apoptosis in T-cell lymphomas.
Specimen part, Disease, Disease stage
View SamplesDevelopmental checkpoints in stem/progenitor cells are critical to the determination, commitment and differentiation into distinct lineages. Cancer cells often retain expression of lineage-specific checkpoint proteins, but their potential impact in cancer remains elusive. T lymphocytes mature in the thymus following a highly orchestrated developmental process that entails the successive rearrangements and expression of T-cell receptor (TCR) genes. Low affinity recognition of self-peptide/MHC complexes (self-pMHC) presented by thymic epithelial cells by the TCR of CD4+CD8+ (DP) cortical thymocytes transduces positive selection signals that ultimately shape the developing T cell repertoire. DP thymocytes not receiving these signals die by lack of stimulation whereas those that recognize self-pMHC with high affinity undergo TCR-mediated apoptosis and negative selection. In T-cell acute lymphoblastic leukaemia (T-ALL), leukaemic transformation of maturating thymocytes results from the acquisition of multiple genetic and epigenetic alterations in oncogenes and tumour suppressor genes, that disrupt the normal regulatory circuits and drive clonal expansion of differentiation-arrested lymphoblasts. We show here that TCR triggering by negatively-selecting self-pMHC prevented T-ALL development and leukaemia maintenance in mice. Induction of TCR signalling by high affinity self-pMHC or treatment with monoclonal antibodies to the CD3 signalling chain (anti-CD3) caused massive leukaemic cell death and a gene expression program resembling that of thymocyte negative selection. Importantly, anti-CD3 treatment hampered leukaemogenesis in mice transplanted with either mouse or patient-derived T-ALLs. These data provide a rationale for targeted therapy based on anti-CD3 treatment of T-ALL patients and demonstrate that endogenous developmental checkpoint proteins are amenable to therapeutic intervention in cancer cells.
Triggering the TCR Developmental Checkpoint Activates a Therapeutically Targetable Tumor Suppressive Pathway in T-cell Leukemia.
Cell line
View SamplesSome infectious agents are associated with non-Hodgkin lymphoma development. Here we have used p53-deficient mice chronically injected with Streptococcus pneumoniae (Spn) with the aim to develop an animal model of infection-associated lymphomagenesis. We show that repeated stimulations with heat-killed Spn significantly enhanced the incidence of peripheral T-cell lymphoma (PTCL) in these mice. Phenotypic studies and gene expression profile analyses indicate that these PTCL arose from chronically stimulated natural killer T (NKT) cells, a T cell lineage that exhibits unique properties. Furthermore, lymphoma development was blocked when these PTCL were transferred to recipients lacking CD1d expression or treated with blocking CD1d mAbs, thus demonstrating that in vivo TCR/CD1d interactions are required for these PTCL survival. In conclusion, we have identified a new entity of peripheral T-cell lymphoma that originates from CD1d-restricted natural killer T (NKT) cells. Our results could refine the classification of PTCL and pave the way for the development of new immunotherapeutic approaches.
CD1d-restricted peripheral T cell lymphoma in mice and humans.
Age, Specimen part
View Samples