Project description:Relapsed acute lymphoblastic leukaemia (ALL) is a leading cause of death due to disease in young people, but the biological determinants of treatment failure remain poorly understood. Recent genome-wide profiling of structural DNA alterations in ALL have identified multiple submicroscopic somatic mutations targeting key cellular pathways, and have demonstrated substantial evolution in genetic alterations from diagnosis to relapse. However, DNA sequence mutations in ALL have not been analysed in detail. To identify novel mutations in relapsed ALL, we resequenced 300 genes in matched diagnosis and relapse samples from 23 patients with ALL. This identified 52 somatic non-synonymous mutations in 32 genes, many of which were novel, including the transcriptional coactivators CREBBP and NCOR1, the transcription factors ERG, SPI1, TCF4 and TCF7L2, components of the Ras signalling pathway, histone genes, genes involved in histone modification (CREBBP and CTCF), and genes previously shown to be targets of recurring DNA copy number alteration in ALL. Analysis of an extended cohort of 71 diagnosis-relapse cases and 270 acute leukaemia cases that did not relapse found that 18.3% of relapse cases had sequence or deletion mutations of CREBBP, which encodes the transcriptional coactivator and histone acetyltransferase CREB-binding protein (CREBBP, also known as CBP). The mutations were either present at diagnosis or acquired at relapse, and resulted in truncated alleles or deleterious substitutions in conserved residues of the histone acetyltransferase domain. Functionally, the mutations impaired histone acetylation and transcriptional regulation of CREBBP targets, including glucocorticoid responsive genes. Several mutations acquired at relapse were detected in subclones at diagnosis, suggesting that the mutations may confer resistance to therapy. These results extend the landscape of genetic alterations in leukaemia, and identify mutations targeting transcriptional and epigenetic regulation as a mechanism of resistance in ALL.
Project description:Chromosomal rearrangements are initiating events in acute lymphoblastic leukaemia (ALL). Here using RNA sequencing of 560 ALL cases, we identify rearrangements between MEF2D (myocyte enhancer factor 2D) and five genes (BCL9, CSF1R, DAZAP1, HNRNPUL1 and SS18) in 22 B progenitor ALL (B-ALL) cases with a distinct gene expression profile, the most common of which is MEF2D-BCL9. Examination of an extended cohort of 1,164 B-ALL cases identified 30 cases with MEF2D rearrangements, which include an additional fusion partner, FOXJ2; thus, MEF2D-rearranged cases comprise 5.3% of cases lacking recurring alterations. MEF2D-rearranged ALL is characterized by a distinct immunophenotype, DNA copy number alterations at the rearrangement sites, older diagnosis age and poor outcome. The rearrangements result in enhanced MEF2D transcriptional activity, lymphoid transformation, activation of HDAC9 expression and sensitive to histone deacetylase inhibitor treatment. Thus, MEF2D-rearranged ALL represents a distinct form of high-risk leukaemia, for which new therapeutic approaches should be considered.
Project description:Acute lymphoblastic leukaemia occurs in both children and adults but its incidence peaks between 2 and 5 years of age. Causation is multifactorial and exogenous or endogenous exposures, genetic susceptibility, and chance have roles. Survival in paediatric acute lymphoblastic leukaemia has improved to roughly 90% in trials with risk stratification by biological features of leukaemic cells and response to treatment, treatment modification based on patients' pharmacodynamics and pharmacogenomics, and improved supportive care. However, innovative approaches are needed to further improve survival while reducing adverse effects. Prognosis remains poor in infants and adults. Genome-wide profiling of germline and leukaemic cell DNA has identified novel submicroscopic structural genetic changes and sequence mutations that contribute to leukaemogenesis, define new disease subtypes, affect responsiveness to treatment, and might provide novel prognostic markers and therapeutic targets for personalised medicine.
Project description:T-cell acute lymphoblastic leukaemia (T-ALL) is a haematological malignancy with a dismal overall prognosis, including a relapse rate of up to 25%, mainly because of the lack of non-cytotoxic targeted therapy options. Drugs that target the function of key epigenetic factors have been approved in the context of haematopoietic disorders, and mutations that affect chromatin modulators in a variety of leukaemias have recently been identified; however, 'epigenetic' drugs are not currently used for T-ALL treatment. Recently, we described that the polycomb repressive complex 2 (PRC2) has a tumour-suppressor role in T-ALL. Here we delineated the role of the histone 3 lysine 27 (H3K27) demethylases JMJD3 and UTX in T-ALL. We show that JMJD3 is essential for the initiation and maintenance of T-ALL, as it controls important oncogenic gene targets by modulating H3K27 methylation. By contrast, we found that UTX functions as a tumour suppressor and is frequently genetically inactivated in T-ALL. Moreover, we demonstrated that the small molecule inhibitor GSKJ4 (ref. 5) affects T-ALL growth, by targeting JMJD3 activity. These findings show that two proteins with a similar enzymatic function can have opposing roles in the context of the same disease, paving the way for treating haematopoietic malignancies with a new category of epigenetic inhibitors.
Project description:Acute lymphoblastic leukaemia with early T-cell precursor immunophenotype (ETP ALL) is a highly aggressive subtype of ALL of unknown aetiology. To gain insights into the genetic basis of this disease, we performed whole genome sequencing of tumour and normal DNA of 12 children with ETP ALL. Analysis of structural and sequence variants in this discovery cohort, and mutation recurrence screening in a panel of 51 ETP and 43 non ETP ALL samples identified a high frequency of activating mutations in genes regulating cytokine receptor and Ras signalling, including IL7R, NRAS, KRAS, FLT3, BRAF, JAK1 and JAK3 in ETP ALL. Moreover, we identified multiple new targets of mutation in including GATA3, EP300, RUNX1, DNM2, ECT2L, HNRNPA1 and HNRNPR, as well as genes known to be mutated in T-ALL, including NOTCH1, PHF6, and WT1.. Five of 12 ETP ALL cases harboured novel chromosomal translocations, several of which accompanied complex multichromosomal rearrangements and resulted in the expression of chimeric in-frame fusion genes disrupting hematopoietic regulators, including ETV6-INO80D, NAP1L1-MLLT10 and RUNX1-EVX1. These results indicate that although ETP ALL is genetically heterogeneous, activation of Ras and cytokine receptor signalling distinguishes this disease from non-ETP ALL. These findings suggest that targeting this pathway may improve the currently dismal outcome of this disease. Gene expression profiling of an extended panel of childhood B-lineage and T-lineage acute lymphoblastic leukemia samples was performed using Affymetrix U133A arrays.
Project description:Acute lymphoblastic leukaemia with early T-cell precursor immunophenotype (ETP ALL) is a highly aggressive subtype of ALL of unknown aetiology. To gain insights into the genetic basis of this disease, we performed whole genome sequencing of tumour and normal DNA of 12 children with ETP ALL. Analysis of structural and sequence variants in this discovery cohort, and mutation recurrence screening in a panel of 51 ETP and 43 non ETP ALL samples identified a high frequency of activating mutations in genes regulating cytokine receptor and Ras signalling, including IL7R, NRAS, KRAS, FLT3, BRAF, JAK1 and JAK3 in ETP ALL. Moreover, we identified multiple new targets of mutation in including GATA3, EP300, RUNX1, DNM2, ECT2L, HNRNPA1 and HNRNPR, as well as genes known to be mutated in T-ALL, including NOTCH1, PHF6, and WT1.. Five of 12 ETP ALL cases harboured novel chromosomal translocations, several of which accompanied complex multichromosomal rearrangements and resulted in the expression of chimeric in-frame fusion genes disrupting hematopoietic regulators, including ETV6-INO80D, NAP1L1-MLLT10 and RUNX1-EVX1. These results indicate that although ETP ALL is genetically heterogeneous, activation of Ras and cytokine receptor signalling distinguishes this disease from non-ETP ALL. These findings suggest that targeting this pathway may improve the currently dismal outcome of this disease. Gene expression profiling of an extended panel of childhood B-lineage and T-lineage acute lymphoblastic leukemia samples was performed using Affymetrix U133A arrays.
Project description:Acute lymphoblastic leukaemia with early T-cell precursor immunophenotype (ETP ALL) is a highly aggressive subtype of ALL of unknown aetiology. To gain insights into the genetic basis of this disease, we performed whole genome sequencing of tumour and normal DNA of 12 children with ETP ALL. Analysis of structural and sequence variants in this discovery cohort, and mutation recurrence screening in a panel of 51 ETP and 43 non ETP ALL samples identified a high frequency of activating mutations in genes regulating cytokine receptor and Ras signalling, including IL7R, NRAS, KRAS, FLT3, BRAF, JAK1 and JAK3 in ETP ALL. Moreover, we identified multiple new targets of mutation in including GATA3, EP300, RUNX1, DNM2, ECT2L, HNRNPA1 and HNRNPR, as well as genes known to be mutated in T-ALL, including NOTCH1, PHF6, and WT1.. Five of 12 ETP ALL cases harboured novel chromosomal translocations, several of which accompanied complex multichromosomal rearrangements and resulted in the expression of chimeric in-frame fusion genes disrupting hematopoietic regulators, including ETV6-INO80D, NAP1L1-MLLT10 and RUNX1-EVX1. These results indicate that although ETP ALL is genetically heterogeneous, activation of Ras and cytokine receptor signalling distinguishes this disease from non-ETP ALL. These findings suggest that targeting this pathway may improve the currently dismal outcome of this disease.
Project description:BackgroundIn B-cell precursor acute lymphoblastic leukaemia (B-ALL), the identification of additional genetic alterations associated with poor prognosis is still of importance. We determined the frequency and prognostic impact of somatic mutations in children and adult cases with B-ALL treated with Spanish PETHEMA and SEHOP protocols.MethodsMutational status of hotspot regions of TP53, JAK2, PAX5, LEF1, CRLF2 and IL7R genes was determined by next-generation deep sequencing in 340 B-ALL patients (211 children and 129 adults). The associations between mutation status and clinicopathological features at the time of diagnosis, treatment outcome and survival were assessed. Univariate and multivariate survival analyses were performed to identify independent prognostic factors associated with overall survival (OS), event-free survival (EFS) and relapse rate (RR).ResultsA mutation rate of 12.4% was identified. The frequency of adult mutations was higher (20.2% vs 7.6%, P=0.001). TP53 was the most frequently mutated gene (4.1%), followed by JAK2 (3.8%), CRLF2 (2.9%), PAX5 (2.4%), LEF1 (0.6%) and IL7R (0.3%). All mutations were observed in B-ALL without ETV6-RUNX1 (P=0.047) or BCR-ABL1 fusions (P<0.0001). In children, TP53mut was associated with lower OS (5-year OS: 50% vs 86%, P=0.002) and EFS rates (5-year EFS: 50% vs 78.3%, P=0.009) and higher RR (5-year RR: 33.3% vs 18.6% P=0.037), and was independently associated with higher RR (hazard ratio (HR)=4.5; P=0.04). In adults, TP53mut was associated with a lower OS (5-year OS: 0% vs 43.3%, P=0.019) and a higher RR (5-year RR: 100% vs 61.4%, P=0.029), whereas JAK2mut was associated with a lower EFS (5-year EFS: 0% vs 30.6%, P=0.035) and a higher RR (5-year RR: 100% vs 60.4%, P=0.002). TP53mut was an independent risk factor for shorter OS (HR=2.3; P=0.035) and, together with JAK2mut, also were independent markers of poor prognosis for RR (TP53mut: HR=5.9; P=0.027 and JAK2mut: HR=5.6; P=0.036).ConclusionsTP53mut and JAK2mut are potential biomarkers associated with poor prognosis in B-ALL patients.
Project description:B cell leukaemia is one of the most frequent malignancies in the paediatric population, but also affects a significant proportion of adults in developed countries. The majority of infant and paediatric cases initiate the process of leukaemogenesis during foetal development (in utero) through the formation of a chromosomal translocation or the acquisition/deletion of genetic material (hyperdiploidy or hypodiploidy, respectively). This first genetic insult is the major determinant for the prognosis and therapeutic outcome of patients. B cell leukaemia in adults displays similar molecular features as its paediatric counterpart. However, since this disease is highly represented in the infant and paediatric population, this review will focus on this demographic group and summarise the biological, clinical and epidemiological knowledge on B cell acute lymphoblastic leukaemia of four well characterised subtypes: t(4;11) MLL-AF4, t(12;21) ETV6-RUNX1, t(1;19) E2A-PBX1 and t(9;22) BCR-ABL1.
Project description:T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematologic malignancy with variable prognosis. It represents 15% of diagnosed pediatric ALL cases and has a threefold higher incidence among males. Many recurrent alterations have been identified and help define molecular subgroups of T-ALL, however the full range of events involved in driving transformation remain to be defined. Using an integrative approach combining genomic and transcriptomic data, we molecularly characterized 30 pediatric T-ALLs and identified common recurrent T-ALL targets such as FBXW7, JAK1, JAK3, PHF6, KDM6A and NOTCH1 as well as novel candidate T-ALL driver mutations including the p.R35L missense mutation in splicesome factor U2AF1 found in 3 patients and loss of function mutations in the X-linked tumor suppressor genes MED12 (frameshit mutation p.V167fs, splice site mutation g.chrX:70339329T>C, missense mutation p.R1989H) and USP9X (nonsense mutation p.Q117*). In vitro functional studies further supported the putative role of these novel T-ALL genes in driving transformation. U2AF1 p.R35L was shown to induce aberrant splicing of downstream target genes, and shRNA knockdown of MED12 and USP9X was shown to confer resistance to apoptosis following T-ALL relevant chemotherapy drug treatment in Jurkat leukemia cells. Interestingly, nearly 60% of novel candidate driver events were identified among immature T-ALL cases, highlighting the underlying genomic complexity of pediatric T-ALL, and the need for larger integrative studies to decipher the mechanisms that contribute to its various subtypes and provide opportunities to refine patient stratification and treatment.