Ulrich G. Steidl

In a previously developed inducible transgenic mouse model of chronic myeloid leukemia, we now demonstrate that the disease is transplantable using BCR-ABL(+) Lin(-)Sca-1(+)c-kit(+) (LSK) cells. Interestingly, the phenotype is more severe when unfractionated bone marrow cells are transplanted, yet neither progenitor cells (Lin(-)Sca-1(-)c-kit(+)), nor mature granulocytes (CD11b(+)Gr-1(+)), nor potential stem cell niche cells (CD45(-)Ter119(-)) are able to transmit the disease or alter the phenotype. The phenotype is largely independent of BCR-ABL priming before transplantation...

The transcription factor PU.1 is an important regulator of hematopoiesis; precise expression levels are critical for normal hematopoietic development and suppression of leukemia. We show here that noncoding antisense RNAs are important modulators of proper dosages of PU.1. Antisense and sense RNAs are regulated by shared evolutionarily conserved cis-regulatory elements, and we can show that antisense RNAs inhibit PU.1 expression by modulating mRNA translation. We propose that such antisense RNAs will likely be important in the regulation of many genes and may be the reason for the large number of overlapping complementary transcripts with so far unknown function...

BACKGROUND: Pegylated granulocyte colony-stimulating factor (G-CSF) has recently been introduced as a new compound for mobilization of CD34(+) hematopoietic stem and progenitor cells. In this study, we compared the molecular and functional characteristics of CD34(+) cells mobilized by pegylated G-CSF with those mobilized by unconjugated G-CSF. DESIGN AND METHODS: Gene expression of immunomagnetically enriched CD34(+) cells from leukapheresis products of patients who were given pegylated-G-CSF or unconjugated G-CSF was analyzed using Affymetrix HG Focus microarrays and quantitative reverse transcriptase polymerase chain reaction...

Targeted disruption of a highly conserved distal enhancer reduces expression of the PU.1 transcription factor by 80% and leads to acute myeloid leukemia (AML) with frequent cytogenetic aberrations in mice. Here we identify a SNP within this element in humans that is more frequent in AML with a complex karyotype, leads to decreased enhancer activity, and reduces PU.1 expression in myeloid progenitors in a development-dependent manner. This SNP inhibits binding of the chromatin-remodeling transcriptional regulator special AT-rich sequence binding protein 1 (SATB1)...

Activating mutations in the epidermal growth factor receptor (EGFR) tyrosine kinase domain determine responsiveness to EGFR tyrosine kinase inhibitors in patients with advanced non-small cell lung cancer (NSCLC). The modulation of transcriptional pathways by mutant EGFR signaling is not fully understood. Previously, we and others identified a single base pair change leading to a threonine to methionine (T790M) amino acid alteration in the ATP-binding pocket of the EGFR as a common mechanism of acquired resistance...

Knockdown of the transcription factor PU.1 (encoded by Sfpi1) leads to acute myeloid leukemia (AML) in mice. We examined the transcriptome of preleukemic hematopoietic stem cells (HSCs) in which PU.1 was knocked down (referred to as 'PU.1-knockdown HSCs') to identify transcriptional changes preceding malignant transformation. Transcription factors c-Jun and JunB were among the top-downregulated targets. Restoration of c-Jun expression in preleukemic cells rescued the PU.1 knockdown-initiated myelomonocytic differentiation block...

OBJECTIVE: Pegfilgrastim has shown to decrease the duration of severe neutropenia after conventional chemotherapy, but its use after high-dose chemotherapy and autologous blood stem cell transplantation has not been established yet. Therefore we studied the efficacy and the pharmacokinetic profile of pegfilgrastim in patients with multiple myeloma undergoing high-dose chemotherapy. METHOD: In total, 21 patients received a single subcutaneous injection of 6 mg pegfilgrastim on day +1 after transplantation and pegfilgrastim plasma levels were measured daily by enzyme-linked immunosorbent assay...

The coreceptor usage of HIV-1 envelope proteins (Env) is mainly dependent on a defined variable region within the V3-loop of Env. Thus, retroviral vectors derived from murine leukemia virus (MLV), which have been pseudotyped with HIV-1 envelope proteins holding different V3-loops, enable selective gene delivery into either CXCR4 or CCR5 positive cultured cells. Here, we tested the distribution of CD4/CCR5-tropic [MLV(HIV)]-pseudotype vectors in transgenic mice expressing CD4 and either CXCR4 or CCR5 of human origin...

BACKGROUND: Current regimens for peripheral blood progenitor cell (PBPC) mobilization in patients with multiple myeloma are based on daily subcutaneous injections of granulocyte-colony-stimulating factor (G-CSF) starting shortly after cytotoxic therapy. Recently a polyethylene glycol-conjugated G-CSF (pegfilgrastim) was introduced that has a substantially longer t(1/2) than the original formula. STUDY DESIGN AND METHODS: The use of pegfilgrastim was examined at two dose levels for PBPC mobilization in patients with Stage II or III multiple myeloma...

Tight regulation of transcription factors, such as PU.1, is crucial for generation of all hematopoietic lineages. We previously reported that mice with a deletion of an upstream regulatory element (URE) of the gene encoding PU.1 (Sfpi1) developed acute myeloid leukemia. Here we show that the URE has an essential role in orchestrating the dynamic PU.1 expression pattern required for lymphoid development and tumor suppression. URE deletion ablated B2 cells but stimulated growth of B1 cells in mice. The URE was a PU...

Differentiation of hematopoietic stem and progenitor cells is under strict control of a regulatory network orchestrated by lineage-specific transcription factors. A block in normal differentiation is a major contributing factor in the development of solid tumors and leukemias. Cells from patients with acute myeloid leukemia (AML) frequently harbor mutated or dysregulated transcription factor genes, suggesting their involvement in leukemogenesis. As a consequence, these alterations diminish the pool of available molecules of a small number of critical transcription factors, such as CCAAT enhancer binding proteins, PU...

Increasing evidence suggests that leukemias are sustained by leukemic stem cells. However, the molecular pathways underlying the transformation of normal cells into leukemic stem cells are still poorly understood. The involvement of a small group of key transcription factors into this process was suggested by their frequent mutation or down-regulation in patients with acute myeloid leukemia (AML). Recent findings in mice with hypomorphic transcription-factor genes demonstrated that leukemic stem-cell formation in AML could directly be caused by reduced transcription-factor activity beyond a critical threshold...

Chronic myelogenous leukemia (CML) is a malignant disorder of the hematopoietic stem cell characterized by the BCR-ABL oncogene. We examined gene expression profiles of highly enriched CD34(+) hematopoietic stem and progenitor cells from patients with CML in chronic phase using cDNA arrays covering 1.185 genes. Comparing CML CD34(+) cells with normal CD34(+) cells, we found 158 genes which were significantly differentially expressed. Gene expression patterns reflected BCR-ABL-induced functional alterations such as increased cell-cycle and proteasome activity...

Recently, overlapping molecular phenotypes of hematopoietic and neuropoietic cells were described in mice. Here, we examined primary human CD34(+) hematopoietic stem and progenitor cells applying specialized cDNA arrays, real-time reverse-transcriptase-polymerase chain reaction (RT-PCR), and fluorescent-activated cell sorter (FACS) analysis focusing on genes involved in neurobiologic functions. We found expression of vesicle fusion and motility genes, ligand- and voltage-gated ion channels, receptor kinases and phosphatases, and, most interestingly, mRNA as well as protein expression of G protein-coupled receptors of neuromediators (corticotropin-releasing hormone 1 [CRH 1] and CRH 2 receptors, orexin/hypocretin 1 and 2 receptors, GABAB receptor, adenosine A(2)B receptor, opioid kappa 1 and mu 1 receptors, and 5-HT 1F receptor)...

The restorative capacity of human CD34(+) hematopoietic cells is clinically used in the autologous and allogeneic transplant setting to support cytotoxic therapy. We examined gene expression patterns of highly enriched bone marrow CD34(+) (BM-CD34(+)) or G-CSF-mobilized peripheral blood CD34(+) (PB-CD34(+)) cells by cDNA array technology, quantitative real-time RT-PCR, and flow cytometry, to identify molecular causes underlying the functional differences between circulating and sedentary hematopoietic stem and progenitor cells...