Project description:T-cell acute lymphoblastic leukemia (T-ALL) is mostly characterized by specific chromosomal abnormalities, some occurring in a mutually exclusive manner possibly delineating specific T-ALL subgroups. One subgroup, including MLL-rearranged, CALM-AF10 or inv(7)(p15q34) cases, is characterized by elevated expression of HOXA genes. Using a gene expression based clustering analysis of 67 T-ALL cases with recurrent molecular genetic abnormalities and 25 samples lacking apparent aberrations, we identified 5 new cases with elevated HOXA levels. Using array-CGH, a cryptic and recurrent deletion, del(9)(q34.11q34.13), was exclusively identified in 3 of these 5 cases. This deletion results in a conserved SET-NUP214 fusion product, that was also identified in the T-ALL cell line LOUCY. SET-NUP214 binds in the promoter regions of specific HOXA genes, where it may interact with CRM1 and DOT1L leading to the transcriptional activation of HOXA genes. Targeted inhibition of SET-NUP214 by siRNA abolished expression of HOXA genes, inhibited proliferation and induced differentiation in LOUCY but not in other T-ALL lines. We conclude that SET-NUP214 may contribute to the pathogenesis of T-ALL by enforcing T-cell differentiation arrest. We combined gene expression profiling and array-CGH analysis to detect a new and recurrent molecular cytogenetic abnormality in T-ALL patients that co-clustered with 5 well-defined HOXA-activated T-ALL samples. We describe the cloning of a recurrent SET-NUP214 fusion product in these samples, and identified a potential mechanism by which SET-NUP214 may activate the HOXA gene cluster as potential leukemogenic event in T-ALL. Experiment Overall Design: For 67 T-ALL patients having one of the major molecular cytogenetic abnormalities (i.e. TAL1 (n=24), LMO2 (n=9), HOXA (n=5), HOX11/TLX1 (n=7), and HOX11L2/TLX3 (n=22)), differentially expressed probesets were calculated from Affymetrix U133plus2.0 data based upon a Wilcoxon analysis and corrected for multiple testing for each probeset. Significant and differentially expressed probesets were obtained for the TAL1, HOX11 and HOX11L2 subgroups. No significant probesets were obtained for the HOXA subgroup or the LMO2 subgroup . As TAL1 and LMO2 both participate in the same transcriptional complex, activation of these genes may both lead to a highly similar expression profile. Combined analysis of TAL1 and LMO2 rearranged cases revealed significant and differentially expressed probesets that, as expected, almost entirely overlapped with the gene signature obtained for the TAL1-subgroup only. Next, we clustered 92 T-ALL cases, that besides the 67 cases as described above further included 25 T-ALL that lacked any of these recurrent abnormalities. Cluster analysis was performed based upon the top 25, 50 or 100 most significant probesets for the TAL1, TAL1/LMO2, HOX11 and HOX11L2 subgroups combined with 15 HOXA probesets identified by Soulier et al (2005)
Project description:T-cell acute lymphoblastic leukemia (T-ALL) is mostly characterized by specific chromosomal abnormalities, some occurring in a mutually exclusive manner possibly delineating specific T-ALL subgroups. One subgroup, including MLL-rearranged, CALM-AF10 or inv(7)(p15q34) cases, is characterized by elevated expression of HOXA genes. Using a gene expression based clustering analysis of 67 T-ALL cases with recurrent molecular genetic abnormalities and 25 samples lacking apparent aberrations, we identified 5 new cases with elevated HOXA levels. Using array-CGH, a cryptic and recurrent deletion, del(9)(q34.11q34.13), was exclusively identified in 3 of these 5 cases. This deletion results in a conserved SET-NUP214 fusion product, that was also identified in the T-ALL cell line LOUCY. SET-NUP214 binds in the promoter regions of specific HOXA genes, where it may interact with CRM1 and DOT1L leading to the transcriptional activation of HOXA genes. Targeted inhibition of SET-NUP214 by siRNA abolished expression of HOXA genes, inhibited proliferation and induced differentiation in LOUCY but not in other T-ALL lines. We conclude that SET-NUP214 may contribute to the pathogenesis of T-ALL by enforcing T-cell differentiation arrest. We combined gene expression profiling and array-CGH analysis to detect a new and recurrent molecular cytogenetic abnormality in T-ALL patients that co-clustered with 5 well-defined HOXA-activated T-ALL samples. We describe the cloning of a recurrent SET-NUP214 fusion product in these samples, and identified a potential mechanism by which SET-NUP214 may activate the HOXA gene cluster as potential leukemogenic event in T-ALL. Keywords: cluster analysis
Project description:This SuperSeries is composed of the following subset Series: GSE35201: Transcriptome Sequence Analysis of Pediatric Acute Megakaryoblastic Leukemia Identifies An Inv(16)(p13.3;q24.3)-Encoded CBFA2T3-GLIS2 Fusion Protein As a Recurrent Lesion in 39% of Non-Infant Cases [2007] GSE35202: Transcriptome Sequence Analysis of Pediatric Acute Megakaryoblastic Leukemia Identifies An Inv(16)(p13.3;q24.3)-Encoded CBFA2T3-GLIS2 Fusion Protein As a Recurrent Lesion in 39% of Non-Infant Cases [2010] Refer to individual Series
Project description:We used ChIP-seq to examine the genome-wide binding of CRM1, SET-Nup214, and NPM1c in leukemia cell lines. Our analysis revealed that CRM1, SET-Nup214, and NPM1c are preferentially targeted to HOX cluster regions.
Project description:A "Cartes d'Identite des Tumeurs" (CIT) project from the french Ligue Nationale Contre le Cancer (http://cit.ligue-cancer.net). 104 samples; Affymetrix U133A micro-arrays.<br> <br> Ninety two patients with T-ALL were diagnosed and treated at Saint-Louis hospital, Paris. Seven patients were studied at diagnosis and relapse (total 99 T-ALL samples). There were 56 children (median age 9 years old; range 1 to 16), and 36 adults (median age 27; range 17 to 66). Informed consent was obtained from the patients and/or relatives. T-ALL diagnosis was based on morphological and immunophenotypical criteria using flow cytometry and an extended monoclonal antibody panel.<br> <br> Using a combination of molecular cytogenetic and large-scale expression analysis in human T-ALL, we identified and characterized a new recurrent chromosomal translocation, targeting the major homeobox gene cluster HOXA and the TCRB locus. Specific quantitative PCR analysis showed that the expression of the whole HOXA gene cluster was dramatically dysregulated in the HOXA-rearranged cases, and also in MLL and CALM-AF10-related T-ALL cases, strongly suggesting that HOXA genes are oncogenic in these leukemias. Inclusion of HOXA-translocated cases in a general molecular portrait of 92 T-ALL based on large-scale expression analysis shows that this rearrangement defines a new homogeneous subgroup, which shares common biological networks with the TLX1 and TLX3-related cases. Since T-ALLs derive from T-cell progenitors, expression profiles of the distinct T-ALL subgroups were analyzed with respect to those of normal human thymic sub-populations. Inappropriate utilization or perturbation of specific molecular networks involved in thymic differentiation was detected. Moreover, we found a significant association between T-ALL oncogenic subgroups and ectopic expression of a limited set of genes, including several developmental genes, namely HOXA, TLX1, TLX3, NKX3-1, SIX6 and TFAP2C. These data strongly support the view that the abnormal expression of developmental genes, including the prototypical homeobox genes HOXA, is critical in T-ALL oncogenesis.<br> <br> Project Leader: <br> FranC'ois Sigaux<br> Institut Universitaire d'Hematologie<br> Hopital Saint Louis, Paris, France<br> <br> Data submission:<br>Fabien Petel
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:The molecular mechanisms involved in disease progression and relapse in T-cell acute lymphoblastic leukemia (T-ALL) are poorly understood. We used single nucleotide polymorphism (SNP) array analysis to analyze paired diagnostic and relapsed T-ALL samples to identify recurrent genetic alterations in T-ALL. This analysis showed a notorious absence of acquired chromosomal changes at relapse. In addition, we identified deletions and associated mutations in the WT1 tumor suppressor gene in 2/9 samples. Subsequent analysis showed WT1 mutations in 28/211 (13.2%) of pediatric and 10/85 (11.7%) of adult T-ALL cases. WT1 mutations present in T-ALL are predominantly heterozygous frameshift mutations resulting in truncation of the C-terminal zinc finger domains of this transcription factor. WT1 mutations are most prominently found in T-ALL cases with aberrant rearrangements of the oncogenic TLX1, TLX3 and HOXA transcription factor oncogenes. Survival analysis demonstrated that WT1 mutations do not confer adverse prognosis in pediatric and adult T-ALL. Overall these results show that overt chromosomal instability does not seem to be a major mutagenic mechanism contributing to disease progression in T-ALL and the presence of WT1 mutations as a recurrent genetic alteration in T-ALL.
Project description:Desmoplastic small round cell tumor (DSRCT) is a rare pediatric cancer caused by the EWSR1-WT1 fusion oncogene. Despite initial response to chemotherapy, DSRCT has a recurrence rate of over 80% leading to poor patient prognosis with a 5-year survival rate of only 15-25%. Owing to the rarity of DSRCT, sample scarcity is a barrier to understanding DSRCT biology and developing effective therapies. Here, we performed RNA-sequencing on a novel pair of primary and recurrent DSRCT tumors harvested from the same patient 5-years apart. To gain insights into gene expression alterations associated with recurrence, we performed pathway analysis on Gene Ontology Biological Processes and KEGG pathways. Upregulated pathways in the recurrent tumor included DNA repair and mRNA splicing related pathways, while downregulated pathways included immune system function and focal adhesion. We further examined the expression of previously identified EWSR1-WT1 regulated targets, a large number of which were enriched in the recurrent tumor. Overall, this study provides novel understanding of DSRCT biology and a new RNA-seq data set to advance future studies.