Almost a quarter of pediatric patients with Acute Lymphoblastic Leukemia (ALL) suffer from relapses. The biological mechanisms underlying therapy response and development of relapses have remained unclear. In an attempt to better understand this phenomenon, we have analyzed 41 matched diagnosis relapse pairs of ALL patients using genomewide expression arrays (82 arrays) on purified leukemic cells. In roughly half of the patients very few differences between diagnosis and relapse samples were found (stable group), suggesting that mostly extra-leukemic factors (e.g., drug distribution, drug metabolism, compliance) contributed to the relapse. Therefore, we focused our further analysis on 20 samples with clear differences in gene expression (skewed group), reasoning that these would allow us to better study the biological mechanisms underlying relapsed ALL. After finding the differences between diagnosis and relapse pairs in this group, we identified four major gene clusters corresponding to several pathways associated with changes in cell cycle, DNA replication, recombination and repair, as well as B cell developmental genes. We also identified cancer genes commonly associated with colon carcinomas and ubiquitination to be upregulated in relapsed ALL. Thus, about half of relapses are due to selection or emergence of a clone with deregulated expression of a genes involved in pathways that regulate B cell signaling, development, cell cycle, cellular division and replication.
Genome-wide expression analysis of paired diagnosis-relapse samples in ALL indicates involvement of pathways related to DNA replication, cell cycle and DNA repair, independent of immune phenotype.
Sex, Specimen part, Disease
View SamplesTo gain more insight into initiation and regulation of T cell receptor (TCR) gene rearrangement during human T cell development, we analyzed TCR gene rearrangements by quantitative PCR analysis in nine consecutive T-cell developmental stages, including CD34+ lin- cord blood cells as a reference. The same stages were used for gene expression profiling using DNA microarrays.
New insights on human T cell development by quantitative T cell receptor gene rearrangement studies and gene expression profiling.
Specimen part
View SamplesT cells develop from progenitors that migrate from the bone marrow into the thymus. Thymocytes are subdivided roughly as being double negative (DN), double positive (DP), or single positive (SP), based on the expression of the CD4 and CD8 coreceptors. The DN stage is heterogeneous and can be subdivided into four distinct subsets in mice based on the expression of CD44 and CD25. In human, three distinct DN stages can be recognized: a CD34+CD38CD1a stage that represents the most immature thymic subset and the consecutive CD34+CD38+CD1a and CD34+CD38+CD1a+ stages. Human DN thymocytes mature via an immature single positive (ISP CD4+) and a DP stage into CD4+ or CD8+ SP T cells that express functional T cell receptors (TCR) and that exit the thymus. In this study, gene expression was measured in each of these nine stages.
New insights on human T cell development by quantitative T cell receptor gene rearrangement studies and gene expression profiling.
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View SamplesBackground In childhood acute lymphoblastic leukemia (ALL), central nervous system (CNS) involvement is rare at diagnosis (1-4%), but more frequent at relapse (~30%). Minimal residual disease diagnostics predict most bone marrow (BM) relapses, but likely cannot predict isolated CNS relapses. Consequently, CNS relapses may become relatively more important. Because of the significant late sequelae of CNS treatment, early identification of patients at risk of CNS relapse is crucial. Methods Gene expression profiles of ALL cells from cerebrospinal fluid (CSF) and ALL cells from BM were compared and differences were confirmed by real-time quantitative PCR. For a selected set of overexpressed genes, protein expression levels of ALL cells in CSF at relapse and of ALL cells in diagnostic BM samples were evaluated by 8-color flow cytometry. Results CSF-derived ALL cells showed a clearly different gene expression profile than BM-derived ALL cells, with differentially-expressed genes (including SCD and OPN) involved in survival and apoptosis pathways and linked to the JAK-STAT pathway. Flowcytometric analysis showed that a subpopulation of ALL cells (>1%) with a CNS signature (SCD positivity and increased OPN expression) was already present in BM at diagnosis in ALL patients who later developed a CNS relapse, but was <1% or absent in virtually all other patients. Conclusions The presence of a subpopulation of ALL cells with a CNS signature at diagnosis may predict isolated CNS relapse. Such information can be used to design new diagnostic and treatment strategies that aim at prevention of CNS relapse with reduced toxicity.
New cellular markers at diagnosis are associated with isolated central nervous system relapse in paediatric B-cell precursor acute lymphoblastic leukaemia.
Sex, Age, Time
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Exploring gene expression biomarker candidates for neurobehavioral impairment from total sleep deprivation.
Subject, Time
View SamplesHealthy human adults were recruited to a sleep lab at Washington State University and remained there 7 consecutive days. Six received a well-rested Control condition of 10 h Time-In-Bed (TIB) nightly.
Exploring gene expression biomarker candidates for neurobehavioral impairment from total sleep deprivation.
Subject, Time
View SamplesHealthy human adults were recruited to a sleep lab at Washington State University and remained there 7 consecutive days. Six received a well-rested Control condition of 10 h Time-In-Bed (TIB) nightly.
Exploring gene expression biomarker candidates for neurobehavioral impairment from total sleep deprivation.
Subject, Time
View SamplesHealthy human adults were recruited to a sleep lab at Washington State University and remained there 7 consecutive days. Six received a well-rested Control condition of 10 h Time-In-Bed (TIB) nightly.
Exploring gene expression biomarker candidates for neurobehavioral impairment from total sleep deprivation.
Subject, Time
View SamplesHRE1 and HRE2 are two ERF transcription factors induced by low oxygen. In this work we analyzed the effect of ectopic expression of HRE1 and HRE2 on the arabidopsis transcriptome in aerobic and hypoxic (1% O2) conditions. While HRE1 has a moderate effect on the expression of anaerobic genes under hypoxia, HRE2 does not affect them either under aerobic or hypoxic conditions.
HRE1 and HRE2, two hypoxia-inducible ethylene response factors, affect anaerobic responses in Arabidopsis thaliana.
Age, Treatment
View SamplesIn this study we analyzed the effect of overexpression of an HA-tagged version of the ERF RAP2.12 on the transcriptome levels in aerobic and hypoxic-treated (O2 21% and 1%, respectively) Arabidopsis thaliana rosettes.
Oxygen sensing in plants is mediated by an N-end rule pathway for protein destabilization.
Treatment
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