Project description:Extensive molecular and prognostic characterization of wild-type MLL infant ALL. Background: Approximately 20% of all infant ALL cases carry wild-type (or germline) MLL genes. To date, wild-type MLL infant ALL patients are generally regarded as young pediatric precursor B-ALL patients, but extensive characterization of this specific patient group largely remains unacknowledged. Methods: We here studied a relatively large cohort of 78 wild-type MLL infant ALL samples, using clinical parameters, array-comparative genomic hybridization analysis, gene expression profiling, multiplex ligation-dependent probe amplification, and conventional sequencing. Findings: Wild-type MLL infant ALL patients are generally characterized by a lower incidence of favourable prognostic factors than pediatric (non-infant) B-ALL patients, and patients at high risk of therapy failure typically display an immature pro-B immunophenotype or respond poorly to prednisone. Using gene expression profiling, we found MEIS1 expression to additionally be highly predictive for clinical outcome in wild-type MLL infant ALL with a favourable prognosis in the wild-type MLL infants with low MEIS1 expression (DFS 88%% versus 50%, p=0•01). Overall the incidence of DNA copy number variations and genetic abnormalities in genes involved in B-cell differentiation is lower in wild-type MLL infant ALL patients as compared with pediatric precursor B-ALL patients. Interpretation: Wild-type MLL infant ALL represents a highly heterogeneous patient group, which cannot be unified by one or a few known recurrent genomic aberrations. High-level MEIS1 expression and an immature pro-B immunophenotype in high-risk wild-type MLL infant ALL patients shows parallel with the unfavourable prognosis of MLL-rearranged infant ALL patients. In contrast, wild-type MLL infant ALL patients expressing lower levels of MEIS1 and displaying more differentiated (pre-B or common) phenotypes may well be more related to pediatric precursor B-ALL patients older than 1 year of age. We advocate that a treatment strategy in wild-type MLL infant ALL based on MEIS1 expression could be beneficial for improving survival.
Project description:Extensive molecular and prognostic characterization of wild-type MLL infant ALL. Background: Approximately 20% of all infant ALL cases carry wild-type (or germline) MLL genes. To date, wild-type MLL infant ALL patients are generally regarded as young pediatric precursor B-ALL patients, but extensive characterization of this specific patient group largely remains unacknowledged. Methods: We here studied a relatively large cohort of 78 wild-type MLL infant ALL samples, using clinical parameters, array-comparative genomic hybridization analysis, gene expression profiling, multiplex ligation-dependent probe amplification, and conventional sequencing. Findings: Wild-type MLL infant ALL patients are generally characterized by a lower incidence of favourable prognostic factors than pediatric (non-infant) B-ALL patients, and patients at high risk of therapy failure typically display an immature pro-B immunophenotype or respond poorly to prednisone. Using gene expression profiling, we found MEIS1 expression to additionally be highly predictive for clinical outcome in wild-type MLL infant ALL with a favourable prognosis in the wild-type MLL infants with low MEIS1 expression (DFS 88%% versus 50%, p=0•01). Overall the incidence of DNA copy number variations and genetic abnormalities in genes involved in B-cell differentiation is lower in wild-type MLL infant ALL patients as compared with pediatric precursor B-ALL patients. Interpretation: Wild-type MLL infant ALL represents a highly heterogeneous patient group, which cannot be unified by one or a few known recurrent genomic aberrations. High-level MEIS1 expression and an immature pro-B immunophenotype in high-risk wild-type MLL infant ALL patients shows parallel with the unfavourable prognosis of MLL-rearranged infant ALL patients. In contrast, wild-type MLL infant ALL patients expressing lower levels of MEIS1 and displaying more differentiated (pre-B or common) phenotypes may well be more related to pediatric precursor B-ALL patients older than 1 year of age. We advocate that a treatment strategy in wild-type MLL infant ALL based on MEIS1 expression could be beneficial for improving survival. Gene expression profiling of wild-type MLL infant ALL. Additional wild-type MLL infant ALL patient samples (n=17) to the earlier samples published under GSE19475 (GSM485309 to GSM485322).
Project description:Although 90% of children with acute lymphoblastic leukemia (ALL) are now cured, the prognosis of infant-ALL (diagnosis within the first year of life) remains dismal. Infant-ALL is usually caused by a single genetic hit that arises in utero: rearrangement of the MLL/KMT2A gene (MLL-r). This is sufficient to give rise to a uniquely aggressive and treatment-refractory leukemia compared to older children with the same MLL-r. The reasons for disparate outcomes in patients of different ages with identical molecular drivers are unknown. This paper addresses the hypothesis that fetal-specific gene expression programs co-operate with MLL-AF4 to initiate and maintain infant-ALL. Using direct comparison of fetal and adult HSC and progenitor transcriptomes we identify fetal-specific gene expression programs in primary human cells. We show that MLL-AF4-driven infant-ALL, but not MLL-AF4 childhood-ALL, displays expression of fetal-specific genes. In a direct test of this observation, we find that CRISPR-Cas9 gene editing of primary human fetal liver cells (to produce a t(4;11)/MLL-AF4 translocation) replicates the clinical features of infant-ALL and drives infant-ALL-specific and fetal-specific gene expression programs. These data strongly support the hypothesis that fetal-specific gene expression programs co-operate with MLL-AF4 to initiate and maintain the distinct biology of infant ALL.
Project description:Gene expression profiling of immortalized human mesenchymal stem cells with hTERT/E6/E7 transfected MSCs. hTERT may change gene expression in MSCs. Goal was to determine the gene expressions of immortalized MSCs.
Project description:Acute Lymphoblastic Leukemia (ALL) in infants (<1 year) is characterized by a poor prognosis and a high incidence of MLL translocations. Several studies demonstrated the unique gene expression profile associated with MLL-rearranged ALL, but generally small cohorts were analyzed as uniform patient groups regardless of the type of MLL translocation, while the analysis of translocation-negative infant ALL remained unacknowledged. We generated and analyzed primary infant ALL expression profiles (n=73) typified by translocations t(4;11), t(11;19) and t(9;11), or the absence of MLL translocations, in order to study translocation-specific gene expression between the different genetic subtypes of infant ALL.