Ines Volkmer

Martin Luther University of Halle-Wittenberg, Halle-on-the-Saale, Saxony-Anhalt, Germany

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Publications (12)25.17 Total impact

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    ABSTRACT: In vitro, the infection of human B-cells with the lymphotropic gammaherpesvirus Epstein-Barr virus (EBV) induces formation of permanently growing lymphoblastoid cell lines (LCL). In a spontaneously outgrown LCL (cell line CSIII), we detected nucleotide sequence variations of the EBV nuclear antigen 1 (EBNA1) RNA that was different from the reference sequence of EBNA1 in the prototypic EBV strain B95-8. In the present study, we molecularly and functionally characterized this virus isolate in comparison to LCL with the prototypic nucleotide sequence. Although we detected high functional similarity between CSIII and the other LCL, our data suggest that the lytic cycle might be ineffective in the CSIII LCL. DNA microarray analysis indicated that RNA binding motif, single stranded interacting protein 1 (RBMS1), which is typically expressed in latency III of EBV to prevent the lytic cycle, was the most overexpressed gene in CSIII LCL.
    Molecular Biology Reports 07/2014; · 2.51 Impact Factor
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    ABSTRACT: Sequencing of individual clones from a newly established cDNA library from the chemoresistant Hodgkin's lymphoma cell line L-1236 led to the isolation of a cDNA clone corresponding to a short sequence from chromosome 1. Reverse transcriptase-polymerase chain reaction indicated high expression of this sequence in Hodgkin's lymphoma derived cell lines but not in normal blood cells. Further characterization of this sequence and the surrounding genomic DNA revealed that this sequence is part of a human endogenous retrovirus locus. The sequence of this endogenous retrovirus is interrupted by a pseudogene of the dual specificity phosphatase 5 (DUSP5). Reverse transcriptase-polymerase chain reaction revealed high expression of this pseudogene (DUSP5P1) in HL cell lines but not in normal blood cells or Epstein-Barr virus-immortalized B cells. Cells from other tumor types (Burkitt's lymphoma, leukemia, neuroblastoma, Ewing sarcoma) also showed a higher DUSP5P1/DUSP5 ratio than normal cells. Furthermore, we observed that higher expression of DUSP5 in relation to DUSP5P1 correlated with the expression of the pro-apoptotic factor B cell leukemia/lymphoma 2-like 11 (BCL2L11) in peripheral blood cells and HL cells. Knock-down of DUSP5 in HL cells resulted in down-regulation of BCL2L11. Thus, the DUSP5/DUSP5P1 system could be responsible for regulation of BCL2L11 leading to inhibition of apoptosis in these tumor cells.
    PLoS ONE 01/2014; 9(2):e89577. · 3.53 Impact Factor
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    ABSTRACT: Curcumin, a phytochemical isolated from curcuma plants which are used as coloring ingredient for the preparation of curry powder, has several activities which suggest that it might be an interesting drug for the treatment or prevention of cancer. Curcumin targets different pathways which are involved in the malignant phenotype of tumor cells, including the nuclear factor kappa B (NFKB) pathway. This pathway is deregulated in multiple tumor entities, including Hodgkin's lymphoma (HL). Indeed, curcumin can inhibit growth of HL cell lines and increases the sensitivity of these cells for cisplatin. In this review we summarize curcumin activities with special focus on possible activities against HL cells.
    Cancer Growth and Metastasis 01/2013; 6:35-52.
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    ABSTRACT: Acute lymphoblastic leukemia (ALL) is the most common childhood cancer. To identify novel candidates for targeted therapy, we performed a comprehensive transcriptome analysis identifying MondoA (MLXIP) - a transcription factor regulating glycolysis - to be overexpressed in ALL compared to normal tissues. Using microarray-profiling, gene-set enrichment analysis, RNA interference and functional assays we show that MondoA overexpression increases glucose catabolism and maintains a more immature phenotype, which is associated with enhanced survival and clonogenicity of leukemia cells. These data point to an important contribution of MondoA to leukemia aggressiveness and make MondoA a potential candidate for targeted treatment of ALL.
    Leukemia research 06/2012; 36(9):1185-92. · 2.36 Impact Factor
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    ABSTRACT: Neuroblastoma (NB) is the most common extra-cranial solid pediatric tumor. The prognosis of patients with NB has been improved during the last decades. However, treatment results for patients with advanced tumor stages are still unsatisfying. NB cells are characterized by a high tendency for spontaneous or induced differentiation. During differentiation, down-regulation of the basic helix-loop-helix transcription factor achaete-scute complex homolog 1 (ASCL1) has been observed but the consequences of ASCL1 down-regulation have not been elucidated. We used RNA interference to knock-down ASCL1 in NB cells. DNA microarray analysis was used for the identification of ASCL1-regulated genes. Furthermore, conventional and quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used for validation of ASCL1-regulated genes. Down-regulation of ASCL1 influenced the expression of several genes. After down-regulation of ASCL1, we observed very high expression of insulin-like growth factor 2 (IGF2), a factor that is known to be induced during differentiation of NB cells. RT-PCR indicated up-regulation of multiple IGF2 transcript variants after ASCL1 knock-down. Our data suggest that the ASCL1-pathway is responsible for the up-regulation of IGF2 during NB differentiation.
    Molecular Biology Reports 03/2011; 38(3):1515-21. · 2.51 Impact Factor
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    ABSTRACT: Retinoids can induce differentiation of neuroblastoma (NB) cells and are in clinical use for the treatment of patients with NB. Despite improvements of standard treatment during the last years, many patients with NB still relapse and new treatment options for these patients are required. We analyzed NB cells after incubation with retinoids by using Affymetrix HG_U133A microarrays, reverse transcription-polymerase chain reaction (RT-PCR), and flow cytometry. Sequencing of RT-PCR products was applied for determination of CD117 mRNA sequences from NB cell lines. In addition, we tested sensitivity of NB cells for the kinase inhibitor imatinib mesylate after treatment with retinoids. Treatment of NB cells with retinoids induced expression of several genes including the retinoid metabolizing enzymes CYP26A1 and CYP26B1. In addition, we observed up-regulation of CD117 (KIT), particularly after long-term treatment with retinoids. Sequencing of CD117 mRNA from NB cell lines revealed heterozygosity for a non-synonymous single nucleotide polymorphism in SH-SY5Y NB cells. Up-regulation of CD117 in NB cells correlated with increased sensitivity for the kinase inhibitor imatinib mesylate. The combination of retinoids with kinase inhibitors might be worth exploring further for the treatment of NB patients.
    Pediatric Blood & Cancer 09/2010; 55(3):464-70. · 2.35 Impact Factor
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    ABSTRACT: Despite improvements in the treatment of patients with Ewing family tumors (EFT), the prognosis for patients with advanced disease is still unsatisfactory. Recently, we identified lipase I as an EFT-associated gene that might be interesting for the development of new immunological or pharmacological treatment strategies. Lipase I is a member of the large protein superfamilies of alpha/beta hydrolases and serine hydrolases. In the present paper we describe high expression of another member of these superfamilies in EFT. By DNA microarray data base mining we found exceptional high expression of alpha/beta hydrolase domain containing 6 (ABHD6) in EFT but not in other sarcomas. Expression of ABHD6 in EFT correlated with expression of another EFT-associated gene, aristaless. Analysis of ABHD6-associated GGAA microsatellites revealed shorter microsatellites in EFT with lack of ABHD6 expression. ABHD6 homologues were found in varying chordata but not in other animal species. Based on homology modeling we predicted the 3D-structure of ABHD6, which shows high similarity with bacterial homoserine transacetylases. High expression of ABHD6 in EFT in comparison to normal tissues and other tumors suggests that ABHD6 might be an interesting new diagnostic or therapeutic target for EFT. However, knock down of ABHD6 in EFT cells did not inhibit tumor cell growth.
    Cancer Science 09/2009; 100(12):2383-9. · 3.48 Impact Factor
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    ABSTRACT: Charcot-Leyden crystal protein (CLC) is a major secretory effector protein of eosinophils. In addition, CLC has been identified as marker for regulatory T-cells and differential expression of CLC has been described under diverse pathological conditions. By analysis of DNA microarray data from peripheral blood mononuclear cells (PBMC) we found differences for the expression of CLC between PBMC that had been cryopreserved or had been used for RNA isolation immediately after cell separation. Reverse transcriptase-polymerase chain reaction (RT-PCR) of separated cell populations indicated that contaminating granulocytes were the main source of CLC transcripts in PBMC. CLC was only detectable in fresh PBMC and not in cryopreserved material. Transcripts corresponding to CLC were also detectable by RT-PCR only in fresh PBMC and eosinophils. Loss of CLC transcripts in PBMC was induced by a short pulse with dimethyl sulfoxide (DMSO), indicating that the freezing medium was responsible for this phenomenon. We conclude that CLC transcripts are lost during cryopreservation in the presence of DMSO and can never be identified as differentially expressed in cryopreserved samples.
    Journal of Immunological Methods 10/2008; 339(1):99-103. · 2.23 Impact Factor
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    ABSTRACT: Cancer/testis antigens (CTA) represent a heterogeneous group of antigens expressed nearly exclusively in tumour cells and testis. Recently, we identified phospholipase A1 beta (a CTA also known as lipase member I, LIPI) as a gene with high expression in Ewing family tumours (EFT). In the present paper we analyzed expression of LIPI in a panel of normal tissues and tumour samples. The expression of CTA in EFT and normal tissues was analyzed by using DNA microarray datasets. Expression of LIPI in EFT, a panel of other tumour samples, and normal tissues was analyzed by using RT-PCR and quantitative RT-PCR. LIPI was expressed in EFT samples but not in other investigated tumour samples. Expression of LIPI in normal tissues was restricted to testis and thyroid. However, expression in these tissues was low compared with EFT. Interestingly testis as well as thyroid expressed all analyzed EFT-associated transcripts, suggesting that these tissues harbour a small cell population with molecular features of EFT. The sensitivity of the LIPI RT-PCR was similar to the sensitivity of the conventional EWSR1-FLI1 RT-PCR, suggesting that LIPI might be useful as additional diagnostic target structure. The human cancer/testis antigen LIPI is highly expressed in Ewing family tumours and can be easily detected by RT-PCR or quantitative RT-PCR. LIPI might be an interesting target for the development of future diagnostic tools or treatment strategies.
    Pediatric Blood & Cancer 09/2008; 51(2):228-34. · 2.35 Impact Factor
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    ABSTRACT: The prognosis of patients with Hodgkin's lymphoma (HL) has been significantly improved as a result of combination treatment including chemotherapy. However, some patients are refractory to chemotherapy. Therefore, identification of new targets might be useful for development of alternative treatment strategies. In addition, identification of markers associated with chemoresistance can be used to identify patients with increased risk of relapse. By using high-density DNA microarrays, we analyzed the gene-expression profile of HL-cell lines in comparison to a set of normal tissues. Furthermore, we tested the sensitivity of HL cells for cytotoxic drugs (cisplatin, etoposide, melphalan) and compared the gene-expression profile of chemotherapy-resistant and -sensitive cell lines. Differentially expressed genes were validated by polymerase chain reaction and flow cytometry. In addition to genes with high expression in all cell lines, we observed differences between the gene-expression profile of chemotherapy-resistant and -sensitive cells. Genes upregulated in resistant cells include cytokine receptors (IL5RA, IL13RA1), markers expressed on antigen-presenting cells (CD40, CD80), as well as genes with known association to chemoresistance, e.g., myristoylated alanine-rich protein kinase C substrate. In addition, the tumor antigen PRAME (preferentially expressed antigen in melanoma) was expressed in resistant cell lines only. Genes with high expression in HL cells might be potential targets for development of future therapeutic interventions. Expression of tumor antigens together with costimulatory molecules in chemotherapy-resistant HL cells might become targets for cytotoxic T-cell responses against HL cells.
    Experimental Hematology 08/2008; 36(7):886-96. · 2.91 Impact Factor
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    ABSTRACT: We characterized the functional properties of mesenchymal stem cells from various human tissues for their potential to differentiate into hepatocyte-like cells in vitro. Mesenchymal stem cells were isolated from human bone marrow (hBM-MSC) and peritoneal and subcutaneous adipose tissues (hpAT-MSC and hsAT-MSC) based on their capacity to adhere to plastic culture surfaces. Cells were analyzed by reverse transcriptase polymerase chain reaction and for urea as well as glycogen synthesis. Their potential for multiple differentiation pathways was investigated by incubation in culture media triggering osteogenic, adipogenic, or hepatogenic features. Global gene expression patterns were analyzed in hepatocyte differentiated hBM-MSC compared with undifferentiated MSC and adult and fetal human liver. Applying osteogenic or adipogenic differentiation conditions, the cells from each tissue under investigation differentiated appropriately. Treatment of the cells with hepatogenic medium induced mRNA transcripts typical for hepatocytes, as well as the onset of urea synthesis and glycogen storage. Analysis of global gene expression patterns revealed that hepatocytes differentiated from hBM-MSC were clearly distinct from undifferentiated MSC. These cells had acquired features of adult as well as fetal human hepatocytes. In vitro, MSC from human bone marrow and adipose tissue differentiated to hepatocyte-like cells closely related to adult elements on the molecular and functional levels.
    Transplantation Proceedings 04/2008; 40(2):620-3. · 0.95 Impact Factor
  • Zeitschrift Fur Gastroenterologie - Z GASTROENTEROL. 01/2008; 46(01).