Biomedical subjects

Ulrike Puhlmann

Publications and source records attributed to Ulrike Puhlmann.

3 recordsLinked to original sources

PubMed2006

Concomitant aberrant overexpression of RUNX1 and NCAM in regenerating bone marrow of myeloid leukemia of Down's syndrome.

BACKGROUND AND OBJECTIVES: Myeloid leukemia of Down's syndrome (ML-DS) has characteristic biological features (e.g. expression of the truncated GATA1s), which are different from those of non-DS childhood acute myeloid leukemias (AML). The objective of this study was to investigate factors predisposing to the development of ML-DS. DESIGN AND METHODS: We analyzed 134 bone marrow specimens from 64 children with ML-DS and non-DS AML during chemotherapy and 7 specimens from DS children with- out leukemia,who did not receive any chemotherapy,The specimens were analyzed by multiparameter flow cytometry and quantitative reverse transcriptase polymerase chain reaction for transcription factors involved in hematopoiesis. RESULTS: Samples taken from children with ML-DS in complete remission during chemotherapy aberrantly expressed CD56 (NCAM) at the surface of monocytic and granulocytic cells. Compared to non-DS AML cases,children with ML-DS had a statistically significant higher proportion of CD56+ cells in the CD33+ fraction: 71%+/-6% vs. 4%+/-1% (p<0.00001). A significant decrease of the amount of CD33+/CD56+ cells was observed during and after maintenance therapy. An increased number of CD33+/CD56+ cells was also present (>85%) in children with DS who did not receive chemotherapy, but showed a left-shift (due to infection), compared with DS children without left-shift (<10% CD33+/CD56+ cells). Within the CD33+/CD56+ fraction, RUNX1 was overexpressed more than 5-fold (p<0.02) compared to CD33+/CD56- cells, whereas there were no differences regarding GATA1, SPI1, ERG or ETS-2 levels. INTERPRETATION AND CONCLUSIONS: The combined overexpression of RUNX1 and NCAM during stress hematopoiesis in children with DS might be a key factor in the development of overt leukemia and/or in the growth advantage of the malignant GATA1s clone in ML- DS.

Adolescent↗

PubMed2005

Immunophenotypic differences between diagnosis and relapse in childhood AML: Implications for MRD monitoring.

BACKGROUND: Determination of antigen expression patterns is, in addition to morphologic analysis, essential to the diagnosis of acute myeloid leukemia (AML). The present study was performed to determine (a) the degree of changes in immunophenotype and their consequences on the monitoring of minimal residual disease (MRD) in childhood AML and (b) whether certain clusters of changes in antigen expression patterns exist between diagnosis and relapse. METHODS: Bone marrow specimens of 48 children enrolled in the German AML-BFM-93/98 (Acute Myeloid Leukemia-Berlin-Frankfurt-Munster) studies were analyzed immunologically, morphologically, and genetically at diagnosis and at first relapse. RESULTS: The immunophenotypes by flow cytometry differed by at least one antigen between samples at presentation and relapse in 42 of 48 children (88%). More children displayed an immature phenotype at relapse (43 of 47, 91.5%, vs. 37 of 48, 77%; P = 0.05) with expression of CD34 and/or CD117. This was reflected by a gain of markers that are associated with lineage immaturity in 18 of 25 (72%) of cases, whereas the loss of such antigens was observed in 6 of 25 (24%) patients. We did not observe significant changes for lineage specific markers, with comparable occurrences of loss or gain of myeloid and lymphoid antigens in the sample pairs. Only minimal changes were seen for morphologic and genetic features. CONCLUSION: An antigenic shift was observed in 88% of cases in this study. The antibody panels used for MRD monitoring in childhood AML should therefore not be restricted to the immunophenotype detected at presentation but should include in particular markers of lineage immaturity. The clinical observation of a shift toward a more immature phenotype of the myeloblasts is consistent with the model of a clonal evolution of a leukemic stem cell.

Acute Disease↗

PubMed2004

Impact of the cyclooxygenase system on doxorubicin-induced functional multidrug resistance 1 overexpression and doxorubicin sensitivity in acute myeloid leukemic HL-60 cells.

Multidrug resistance (MDR), a challenge in treating childhood acute myeloid leukemia (AML), is frequently associated with decreased drug accumulation caused by multidrug transporter MDR1. Doxorubicin, an important anti-AML drug, is a known MDR1 substrate and inducer. Its cytostatic efficacy is thus limited by MDR1 overexpression. A recent study demonstrated cyclooxygenase-2-dependent, prostaglandin E(2) (PGE(2))-mediated regulation of mdr1b expression in primary rat hepatocyte cultures. Cyclooxygenase-2 expression is increased in several malignancies and considered a negative prognostic factor. Our study focused on cyclooxygenase system's impact on drug-induced MDR1 overexpression in AML cells. As a prerequisite, coexpression of MDR1 and cyclooxygenase-2 mRNA in HL-60 cells and primary AML blasts was demonstrated by Northern blot. Interestingly, incubation of AML cells with doxorubicin not only induced functionally active MDR1 overexpression but also mediated increased cyclooxygenase-2 mRNA and protein expressions with subsequent PGE(2) release (determined by flow cytometry, rhodamine123 efflux assay, reverse transcription-polymerase chain reaction, and enzyme-linked immunosorbent assay). After preincubation and subsequent parallel treatment with the cyclooxygenase-2-preferential inhibitor meloxicam, doxorubicin-induced MDR1 overexpression and function were reduced (maximally at 0.1-0.5 microM meloxicam), whereas cytostatic efficacy of doxorubicin in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assays was significantly increased by up to 78 (HL-60) and 30% (AML blasts) after 72 h of doxorubicin treatment. In HL-60 cells, meloxicam-dependent effect on doxorubicin cytotoxicity was neutralized by PGE(2) preincubation. In conclusion, the cyclooxygenase system, especially the cyclooxygenase-2 isoform, might be involved in regulating doxorubicin-induced MDR1 overexpression in AML cells, with PGE(2) seeming to be a mediating factor. Cyclooxygenase inhibitors thus bear promise to overcome MDR in AML and improve therapy.

ATP Binding Cassette Transporter, Subfamily B, Mem↗