Are you Christiane Schumann?

Claim your profile

Publications (6)34.68 Total impact

  • Article: Centrosome aberrations in bone marrow cells from patients with myelodysplastic syndromes correlate with chromosomal instability.
    [show abstract] [hide abstract]
    ABSTRACT: Centrosomes play important roles in the maintenance of genetic stability and centrosomal aberrations are a hallmark of cancer. Deregulation of centriole duplication leads to supernumerary centrosomes, sister chromatid missegregation and could result in chromosomal instability (CIN) and aneuploidy. CIN is a common feature in at least 45 % of patients with myelodysplastic syndromes (MDS). Therefore, we sought to investigate the centrosomal status and its role for development of CIN in bone marrow (BM) cells of MDS patients. BM cells of 34 MDS patients were examined cytogenetically. Furthermore, cells were immunostained with a centrosome-specific antibody to pericentrin to analyze the centrosomal status. Umbilical cord blood specimens and BM cells of healthy persons (n = 11 and n = 4) served as controls. In addition, the protein expression of the protease separase responsible for genetic stability was examined by western blot analysis. Centrosome abnormalities were detected in 10 % (range, 4-17 %) of cells of MDS samples, but in only 2 % (range, 0-4 %) of cells of healthy controls. Normal karyotypes were found in control cells and in BM cells of 16/34 MDS patients. The incidence of centrosomal alterations was higher in BM cells of patients with cytogenetic alterations (mean, 12 %) compared to BM cells of patients without cytogenetic changes (mean, 7 %). Our results indicate that centrosome alterations are a common and early detectable feature in MDS patients and may contribute to the acquisition of chromosomal aberrations. We assume that centrosome defects could be involved in disease progression and may serve as a future prognostic marker.
    Annals of Hematology 05/2013; · 2.62 Impact Factor
  • Article: Characteristics of MDS patients seen at private practices differ significantly from those treated at university hospitals in Germany.
    [show abstract] [hide abstract]
    ABSTRACT: Myelodysplastic syndromes (MDS) are mainly a disease of the elderly. Commonly, MDS patients are treated in an outpatient setting making hematological/oncological private practices (PP) an important backbone in the management of MDS patients. To gain more insights into the characteristics of patients with MDS treated in hematological/oncological PP and to evaluate the daily diagnostic routines and classification systems used, we performed questionnaire-based analyses. Moreover, to investigate whether characteristics of MDS in PP differ from patients treated in specialized MDS centers in university hospitals (UH), we compared both cohorts of MDS patients. In total, 197 patients in PP and 165 patients in UH were enrolled. Patients in UH were significantly younger as compared to PP. Furthermore, in UH, a greater proportion of patients with international prognostic scoring system (IPSS) higher risk were found, whereas patients with IPSS lower risk were more frequent in PP. In addition, patients in UH had significantly lower hemoglobin levels and platelet counts compared to PP. Our data show that PP and UH are approached by different MDS patient cohorts resulting in different diagnostic workups of MDS patients.
    Journal of Cancer Research and Clinical Oncology 02/2012; 138(6):953-7. · 2.56 Impact Factor
  • Article: Clinical management of gastrointestinal disturbances in patients with myelodysplastic syndromes receiving iron chelation treatment with deferasirox.
    [show abstract] [hide abstract]
    ABSTRACT: Myelodysplastic syndromes are characterized by ineffective hematopoiesis resulting in peripheral cytopenias. The majority of patients is dependent on regular transfusions of packed red blood cells leading to a secondary iron overload which might result in organ damage. Therefore, sufficient iron chelation therapy in selected patients is mandatory. Deferasirox (DFX) is an orally administered iron chelator which has been highly efficient in the treatment of secondary iron overload. Most frequent side effects of DFX are gastrointestinal disturbances, which leads in some patients to low adherence to the therapy. An expert panel met in Lisbon in July 2010 to develop recommendations on prevention and management of GI disturbances based on existing data and personal experiences.
    Leukemia research 09/2011; 35(9):1131-5. · 2.36 Impact Factor
  • Article: Prognostic significance of ASXL1 mutations in patients with myelodysplastic syndromes.
    [show abstract] [hide abstract]
    ABSTRACT: To study the incidence and prognostic impact of mutations in Additional sex comb-like 1 (ASXL1) in a large cohort of patients with myelodysplastic syndrome (MDS). Overall, 193 patients with MDS and 65 healthy volunteers were examined for ASXL1 mutations by direct sequencing and for expression levels of ASXL1. The prognostic impact of ASXL1 mutation and expression levels was evaluated in the context of other clinical and molecular prognostic markers. Mutations in ASXL1 occurred with a frequency of 20.7% in MDS (n = 40 of 193) with 70% (n = 28) of mutations being frameshift mutations and 30% (n = 12) being heterozygous point mutations leading to translational changes. ASXL1 mutations were correlated with an intermediate-risk karyotype (P = .002) but not with other clinical parameters. The presence of ASXL1 mutations was associated with a shorter overall survival for frameshift and point mutations combined (hazard ratio [HR], 1.744; 95% CI, 1.08 to 2.82; P = .024) and for frameshift mutations only (HR, 2.06; 95% CI, 1.21 to 3.50; P = .008). ASXL1 frameshift mutations were associated with a reduced time to progression of acute myeloid leukemia (AML; HR 2.35; 95% CI, 1.17 to 4.74; P = .017). In multivariate analysis, when considering karyotype, transfusion dependence, and IDH1 mutation status, ASXL1 frameshift mutations remained an independent prognostic marker in MDS (overall survival: HR, 1.85; 95% CI, 1.03 to 3.34; P = .040; time to AML progression: HR, 2.39; 95% CI, 1.12 to 5.09; P = .024). These results suggest that ASXL1 mutations are frequent molecular aberrations in MDS that predict an adverse prognostic outcome. Screening of patients for ASXL1 mutations might be useful for clinical risk stratification and treatment decisions in the future.
    Journal of Clinical Oncology 06/2011; 29(18):2499-506. · 18.37 Impact Factor
  • Article: Transcriptional down-regulation of the Wnt antagonist SFRP1 in haematopoietic cells of patients with different risk types of MDS.
    [show abstract] [hide abstract]
    ABSTRACT: Secreted frizzled related protein 1 (SFRP1) is an extracellular antagonist of the Wnt signalling pathway that plays an important role in the pathogenesis of solid tumours and haematopoietic malignancies. SFRP1 has been observed to be transcriptionally down-regulated due to hypermethylation in acute and chronic leukaemia, but so far not in myelodysplastic syndrome (MDS). Moreover, it has been shown that the epigenetic inactivation of SFRP1 correlates with an overexpression of the Wnt receptor Frizzled 3 (Fzd3) in acute leukaemia. Using real-time quantitative reverse transcription polymerase chain reaction (RT-PCR) we examined mRNA expression of SFRP1 and Fzd3 in bone marrow cells derived from 121 patients with different risk types of MDS, acute myeloid leukaemia (AML) and acute lymphoblastic leukaemia (ALL). We employed pyrosequencing to quantify promoter DNA methylation in MDS and acute leukaemia. We detected significant lower mRNA transcription of SFRP1 in MDS compared to healthy individuals. However, DNA sequence mutations or frequent elevated DNA methylation levels of the SFRP1 promoter could not be observed in MDS but in AML and ALL as previously reported. The expression levels of Fzd3 were up-regulated in both acute leukaemia and MDS. Our data show a significant transcriptional down-regulation of SFRP1 as a common event in AML, ALL and - as demonstrated for the first time - in MDS. An inactivation of SFRP1 and the transcriptional up-regulation of Fzd3 seem to be associated with an activation of the Wnt signalling pathway in these haematopoietic diseases.
    Leukemia research 12/2010; 34(12):1610-6. · 2.36 Impact Factor
  • Source
    Article: IDH1 mutations in patients with myelodysplastic syndromes are associated with an unfavorable prognosis.
    [show abstract] [hide abstract]
    ABSTRACT: Myelodysplastic syndromes are a heterogeneous group of hematopoietic stem cell disorders with a high propensity to transform into acute myeloid leukemia. Heterozygous missense mutations in IDH1 at position R132 and in IDH2 at positions R140 and R172 have recently been reported in acute myeloid leukemia. However, little is known about the incidence and prognostic impact of IDH1 and IDH2 mutations in myelodysplastic syndromes. We examined 193 patients with myelodysplastic syndromes and 53 patients with acute myeloid leukemia arising from myelodysplastic syndromes for mutations in IDH1 (R132), IDH2 (R172 and R140), and NPM1 by direct sequencing. We found that mutations in IDH1 occurred with a frequency of 3.6% in myelodysplastic syndromes (7 mutations in 193 patients) and 7.5% in acute myeloid leukemia following myelodysplastic syndromes (4 mutations in 53 patients). Three mutations in codon R140 of IDH2 and one mutation in codon R172 were found in patients with acute myeloid leukemia following myelodysplastic syndromes (7.5%). No IDH2 R140 or R172 mutations were identified in patients with myelodysplastic syndromes. The presence of IDH1 mutations was associated with a shorter overall survival (HR 3.20; 95% CI 1.47-6.99) and a higher rate of transformation into acute myeloid leukemia (67% versus 28%, P=0.04). In multivariate analysis when considering karyotype, transfusion dependence and International Prognostic Scoring System score, IDH1 mutations remained an independent prognostic marker in myelodysplastic syndromes (HR 3.57; 95% CI 1.59-8.02; P=0.002). These results suggest that IDH1 mutations are recurrent molecular aberrations in patients with myelodysplastic syndromes, and may become useful as a poor risk marker in these patients. These findings await validation in prospective trials.
    Haematologica 10/2010; 95(10):1668-74. · 6.42 Impact Factor