liu.seSearch for publications in DiVA
Change search
Refine search result
1 - 15 of 15
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Engström, Linda
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Rosén, Khadijah
    Angel, Anna
    Linköping University, Department of Clinical and Experimental Medicine, Developmental Biology-IKE . Linköping University, Faculty of Health Sciences.
    Fyrberg, Anna
    Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology . Linköping University, Faculty of Health Sciences.
    Mackerlova, Ludmila
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Konsman, Jan Pieter
    Engblom, David
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Blomqvist, Anders
    Linköping University, Department of Clinical and Experimental Medicine, Cell Biology. Linköping University, Faculty of Health Sciences.
    Systemic immune challenge activates an intrinsically regulated local inflammatory circuit in the adrenal gland2008In: Endocrinology, ISSN 0013-7227, E-ISSN 1945-7170, Vol. 149, no 4, p. 1436-1450Article in journal (Refereed)
    Abstract [en]

    There is evidence from in vitro studies that inflammatory messengers influence the release of stress hormone via direct effects on the adrenal gland; however, the mechanisms underlying these effects in the intact organism are unknown. Here we demonstrate that systemic inflammation in rats elicited by iv injection of lipopolysaccharide results in dynamic changes in the adrenal immune cell population, implying a rapid depletion of dendritic cells in the inner cortical layer and the recruitment of immature cells to the outer layers. These changes are accompanied by an induced production of IL-1β and IL-1 receptor type 1 as well as cyclooxygenase-2 and microsomal prostaglandin E synthase-1 in these cells, implying local cytokine-mediated prostaglandin E2 production in the adrenals, which also displayed prostaglandin E2 receptors of subtypes 1 and 3 in the cortex and medulla. The IL-1β expression was also induced by systemically administrated IL-1β and was in both cases attenuated by IL-1 receptor antagonist, consistent with an autocrine signaling loop. IL-1β similarly induced expression of cyclooxygenase-2, but the cyclooxygenase-2 expression was, in contrast, further enhanced by IL-1 receptor antagonist. These data demonstrate a mechanism by which systemic inflammatory agents activate an intrinsically regulated local signaling circuit that may influence the adrenals’ response to immune stress and may help explain the dissociation between plasma levels of ACTH and corticosteroids during chronic immune perturbations.

  • 2.
    Fyrberg, Anna
    Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology . Linköping University, Faculty of Health Sciences.
    Nucleoside analoge cytotoxicity-focus on enzyme regulation, metabolism, and mechanisms of resistance2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The aim of this thesis was to determine the role of nucleoside analog activating and deactivating enzymes in nucleoside analog metabolism and resistance development. Nucleoside analogs are anti-cancer drogs and are often used to treat different leukemias, attributably to presence of high levels of nucleoside analog activating enzymes in hematopoietic cells. More recently some of the newer analogs have been used  successfully to treat solid tumors as well.

    We have used human leukemic cell lines, and isolated cells from patients with leukemia, to investigate the nucleoside analog activating enzymes deoxycytidine kinase (dCK) and deoxyguanosine kinase (dGK) and some of the deactivating enzymes called 5'nucleotidases (5'-NTs). We have measured mRNA expressions and enzymatic activities and correlated them with the cytotoxic response to nuc1eoside analogs and changes in cell cycle progression. We optimized and evaluated a siRNA-transfection method and decreased the activities of dCK and dGK in two different cell lines in order to find out more about their respective contribution to activation of these drogs. An expression microarray analysis of a nucleoside analog resistant cell line was also performed in order to clarify which genes are involved in development of resistance.

    We found that expressions and activities of dCK and dGK were not correlated. The enzyme activities of activating and deactivating enzymes changed during cell cycle progression, giving actively proliferating cells a more favorable enzymatic profile with regard to nucleoside analog cytotoxicity.

    The activities of dCK and dGK could be reduced transiently in leukemic and solid tumor cell lines, thereby confer either resistance or increased sensitivity to nucleoside analogs to variable degrees. Expression microarray analysis was used to evaluate the effect of the transfection method and the specificity of siRNA. We concluded that cells tolerated the transfection weIl without major effects on gene expression, and considered the siRNA used to be specific to its target.

    An expression microarray experiment on a nucleoside analog-induced resistant cell line revealed a hypomethylating capacity of the drog and induction of fetal hemoglobin and a multidrog resistance efflux pump as a result of the hypomethylation. This pump should not be affected by nucleoside analoges since they are not a substrate of it, and upregulation of the pump unfortunately renders the cells highly cross-resistant to different types of drogs. Our preliminary data supports our theory that it may be upregulated in order to help excrete hemoglobin that otherwise would be toxic to the cells.

    List of papers
    1. The pattern of deoxycytidine- and deoxyguanosine kinase activity in relation to messenger RNA expression in blood cells from untreated patients with B-cell chronic lymphocytic leukemia
    Open this publication in new window or tab >>The pattern of deoxycytidine- and deoxyguanosine kinase activity in relation to messenger RNA expression in blood cells from untreated patients with B-cell chronic lymphocytic leukemia
    Show others...
    2006 (English)In: Biochemical Pharmacology, ISSN 0006-2952, E-ISSN 1356-1839, Vol. 71, no 6, p. 882-890Article in journal (Refereed) Published
    Abstract [en]

    Deoxycytidine kinase (dCK) and deoxyguanosine kinase (dGK) catalyze the first step in the intracellular cascade of fludarabine (2-fluoroadenine-β- d-arabinofuranoside) and cladribine (2-chlorodeoxyadenosine) phosphorylation, which leads to activation of these prodrugs, commonly used for treatment of chronic lymphocytic leukemia (CLL). Thus, resistance to nucleoside analogues may primarily be due to low levels of deoxynucleoside kinase activity. The purpose of this study was to investigate the activity profiles of dCK and dGK and characterize the possible relationship between the levels of dCK enzymatic activities and mRNA levels in B-CLL cells from untreated patient samples in an attempt to determine the best approach for predicting sensitivity to nucleoside analogues and thereby optimizing treatment of CLL. For this purpose, dCK and dGK analyses were done in blood cells from 59 untreated symptomatic patients with CLL. The dGK activity towards 2-chlorodeoxyadenosine was significantly lower than of dCK (median 73 pmol/mg protein/min (85-121, 95% CI) versus 353 pmol/mg protein/min (331-421)). The median dCK mRNA level was 0.107 (0.096-0.120, 95% CI). There was a lack of correlation between the activities of dCK and dGK, which indicates that these proteins are regulated independently. We also found that the dCK and dGK activity measurement towards their endogenous substrates were comparable to the nucleoside analogues tested. Such variations in enzyme activities and mRNA levels may well explain differences in clinical responses to treatment. There was no correlation between the levels of dCK mRNAs and enzymatic activities using a quantitative real-time PCR procedure. Sequencing of dCK mRNA did not reveal alternate splicing or mutations in the coding region. The relation between activity and mRNA levels was studied by short interfering RNA (siRNA) method, which showed that in the siRNA treated cells the down-regulation of dCK expression, and activity followed each other. However, in control cells the mRNA levels remained stable but the protein activity markedly decreased. These data demonstrate that the dCK activity is not reflected by dCK mRNA expression that indicates a post-translational mechanism(s). © 2005 Elsevier Inc. All rights reserved.

    Keywords
    Purine analogues; Deoxycytidine kinase; Deoxyguanosine kinase; Chronic lymphocytic leukemia
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-36125 (URN)10.1016/j.bcp.2005.12.007 (DOI)30004 (Local ID)30004 (Archive number)30004 (OAI)
    Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2018-03-21
    2.
    The record could not be found. The reason may be that the record is no longer available or you may have typed in a wrong id in the address field.
    3.
    The record could not be found. The reason may be that the record is no longer available or you may have typed in a wrong id in the address field.
    4. The role of deoxyguanosine kinase for nucleoside analog activation in leukemic and solid tumor cell lines
    Open this publication in new window or tab >>The role of deoxyguanosine kinase for nucleoside analog activation in leukemic and solid tumor cell lines
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Screening malignant melanoma cell lines against nucleoside analogs revealed as high sensitivity to fludarabine, clofarabine, and gemcitabine as to leukemic cells, and especially in those cells expressing high levels of the mitochondrial enzyme deoxuguanosine kinase (dGK). This enzyme, together with the cytosolic deoxycytidine kinase (dCK), and the mitochondrial thymidine kinase 2 (TK2) contributes to the activation of natural deoxyribonucleosides and nucleoside analogs to phosphorylated compounds. dCK is the most prominent enzyme in hematopoietic cells, while dGK may be high in cells harbouring many mitochondria, such as neurons and melanocytes. We found that dGK mRNA and protein expression was considerably higher in melanoma cells than in a leukemic cell line, while the difference at the activity level was less profound.

    Downregulation of dGK in the melanoma cell line RaH5 using siRNA led to a compensatory increase in TK2 activity, which led to significantly increased sensitivity of the cells to gemcitabine. In contrast, downregulation of dGK in the human leukemic CEM cell line decreased TK2 activity, and rendered the cells more resistant to the drugs. The compensatory regulation of deoxynucleoside kinases with over-lapping substrate specificity differed in leukemic and melanoma cell lines probably because they preferably rely on different deoxynucleoside kinases for nucleoside and nucleoside analog activation. dGK and TK2 that are both located in the mitochondria, seems to be able to compensate for each other to a higher extent in the dGK-dependent melanoma cells compared to CEM cells that possess high dCK activity. Solid tumors, such as melanoma, expressing high levels of dGK should be considered for nucleoside analog therapy preferably in combination with their standard treatment.

    Keywords
    Deoxyguanosine kinase, melanoma, leukemia, nucleoside analog, RNAi
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-64066 (URN)
    Available from: 2011-01-12 Created: 2011-01-12 Last updated: 2011-01-12Bibliographically approved
    5. Induction of fetal hemoglobin and ABCB1 gene expression in 9-β-D-arabinofuranosylguanine-resistant MOLT-4 cells
    Open this publication in new window or tab >>Induction of fetal hemoglobin and ABCB1 gene expression in 9-β-D-arabinofuranosylguanine-resistant MOLT-4 cells
    2011 (English)In: Cancer Chemotherapy and Pharmacology, ISSN 0344-5704, E-ISSN 1432-0843, Vol. 68, no 3, p. 583-591Article in journal (Refereed) Published
    Abstract [en]

    PURPOSE: To characterize resistance mechanisms to the nucleoside analog 9-β-D-arabinofuranosylguanine (AraG) in the T-cell acute lymphoblastic leukemia cell line MOLT-4 and its AraG-resistant variant.

    METHODS: A gene expression microarray analysis was performed, as well as gene expression and enzyme activity measurements of key enzymes in the activation of AraG. Cytotoxicity of AraG and cross-resistance to other compounds were evaluated using a standard cytotoxicity assay.

    RESULTS: Gene expression microarray analysis revealed that fetal hemoglobin genes and the multidrug resistance ABCB1 gene, encoding the drug efflux pump P-gp, were the most highly upregulated genes in the resistant cells, while genes traditionally associated with nucleoside analog resistance were not. Fetal hemoglobin and ABCB1 induction can be due to global DNA hypomethylation. This phenomenon was studied using AraG during a period of 4 weeks in MOLT-4 cells and the lung adenocarcinoma cell line A549, leading to up-regulation of hemoglobin gamma and ABCB1 as well as DNA hypomethylation. Inhibiting P-gp in the AraG-resistant MOLT-4 cells led to decreased proliferation, reduced hemoglobin expression, and highly induced ABCB1 expression.

    CONCLUSIONS: We show that AraG can cause hypomethylation of DNA and induce the expression of the fetal hemoglobin gamma gene and the ABCB1 gene. We speculate that the induction of ABCB1/P-gp may occur in order to help with excretion of hemoglobin degradation products that would otherwise be toxic to the cells, and we present data supporting our theory that P-gp may be linked to the induction of hemoglobin.

    Place, publisher, year, edition, pages
    Springer, 2011
    Keywords
    9-β-D-arabinofuranosylguanine - Fetal hemoglobin - P-glycoprotein - Microarray - Hypomethylation
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-63246 (URN)10.1007/s00280-010-1524-5 (DOI)000294345400004 ()21110023 (PubMedID)
    Note
    Funding Agencies|Swedish Cancer Foundation||Swedish Childhood Cancer Foundation||Signe and Olof Wallentin Foundation||Capios Research Foundation||County Council of Ostergotland||Swedish Fund for Research without Animal Experiments||Available from: 2010-12-13 Created: 2010-12-13 Last updated: 2017-12-11
  • 3.
    Fyrberg, Anna
    et al.
    Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology . Linköping University, Faculty of Health Sciences.
    Albertioni, Freidoun
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Pharmacology.
    Lotfi, Kourosh
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Pharmacology. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Pharmacology.
    Cell cycle effect on the activity of deoxynucleoside analogue metabolising enzymes2007In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 357, no 4, p. 847-853Article in journal (Refereed)
    Abstract [en]

    Deoxynucleoside analogues (dNAs) are cytotoxic towards both replicating and indolent malignancies. The impact of fluctuations in the metabolism of dNAs in relation to cell cycle could have strong implications regarding the activity of dNAs. Deoxycytidine kinase (dCK) and deoxyguanosine kinase (dGK) are important enzymes for phosphorylation/activation of dNAs. These drugs can be dephosphorylated/deactivated by 5′-nucleotidases (5′-NTs) and elevated activities of 5′-NTs and decreased dCK and/or dGK activities represent resistance mechanisms towards dNAs. The activities of dCK, dGK, and three 5′-NTs were investigated in four human leukemic cell lines in relationship to cell cycle progression and cytotoxicity of dNAs. Synchronization of cell cultures to arrest in G0/G1 by serum-deprivation was performed followed by serum-supplementation for cell cycle progression. The activities of dCK and dGK increased up to 3-fold in CEM, HL60, and MOLT-4 cells as they started to proliferate, while the activity of cytosolic nucleotidase I was reduced in proliferating cells. CEM, HL60, and MOLT-4 cells were also more sensitive to cladribine, cytarabine, 9-β-d-arabinofuranosylguanine and clofarabine than K562 cells which demonstrated lower levels and less alteration of these enzymes and were least susceptible to the cytotoxic effects of most dNAs. The results suggest that, in the cell lines studied, the proliferation process is associated with a general shift in the direction of activation of dNAs by inducing activities of dCK/dGK and reducing the activity of cN-I which is favourable for the cytotoxic effects of cladribine, cytarabine and, 9-β-d-arabinofuranosylguanine. These results emphasize the importance of cellular proliferation and dNA metabolism by both phosphorylation and dephosphorylation for susceptibility to dNAs. It underscores the need to understand the mechanisms of action and resistance to dNAs in order to increase efficacy of dNAs treatment by new rational. © 2007 Elsevier Inc. All rights reserved.

  • 4.
    Fyrberg, Anna
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Pharmacology.
    Albertioni, Freidoun
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Pharmacology.
    Lotfi, Kourosh
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Pharmacology. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Pharmacology.
    Evidence of cell cycle-dependent regulation of Deoxycytidine kinase and Cytosolic 5-nucleotidase-I activity2005In: 10th European Society for the Study of Purine and Pyrimidine Metabolism in Man,2005, 2005Conference paper (Other academic)
  • 5.
    Fyrberg, Anna
    et al.
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Albertioni, Freidoun
    Cancer Center Karolinska, Department of Oncology and Pathology, Karolinska University Hospital, Stockholm.
    Lotfi, Kourosh
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Haematology. Linköping University, Faculty of Health Sciences.
    RNAi Depletion of Deoxycytidine and Deoxyguanosine Kinase in Human Leukemic CEM Cells2008In: Nucleosides, Nucleotides & Nucleic Acids, ISSN 1525-7770, E-ISSN 1532-2335, Vol. 27, no 6-7, p. 712-719Article in journal (Refereed)
    Abstract [en]

    Resistance toward nucleoside analogues is often due to decreased activities of the activating enzymes deoxycytidine kinase (dCK) and/or deoxyguanosine kinase (dGK). With small interfering RNA (siRNA), dCK and dGK were downregulated by approximately 70% in CEM cells and tested against six nucleoside analogues using the methyl thiazol tetrazolium assay. SiRNA-transfected cells reduced in dCK activity were 3- to 6-fold less sensitive to CdA, AraC, and CAFdA. The sensitivity to AraG and FaraA was unchanged, while the sensitivity toward gemcitabine was significantly increased. dGK depletion in cells resulted in lower sensitivity to FaraA, dFdC, CAFdA, and AraG, but slightly higher sensitivity to CdA and AraC.

  • 6.
    Fyrberg, Anna
    et al.
    Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology . Linköping University, Faculty of Health Sciences.
    Albertioni, Freidoun
    Cancer Center Karolinska Department of Oncology and Pathology, Karolinska University Hospital, SE-171 76 Stockholm.
    Lotfi, Kourosh
    Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Diagnostics, Department of Clinical Pharmacology.
    The role of deoxyguanosine kinase for nucleoside analog activation in leukemic and solid tumor cell linesManuscript (preprint) (Other academic)
    Abstract [en]

    Screening malignant melanoma cell lines against nucleoside analogs revealed as high sensitivity to fludarabine, clofarabine, and gemcitabine as to leukemic cells, and especially in those cells expressing high levels of the mitochondrial enzyme deoxuguanosine kinase (dGK). This enzyme, together with the cytosolic deoxycytidine kinase (dCK), and the mitochondrial thymidine kinase 2 (TK2) contributes to the activation of natural deoxyribonucleosides and nucleoside analogs to phosphorylated compounds. dCK is the most prominent enzyme in hematopoietic cells, while dGK may be high in cells harbouring many mitochondria, such as neurons and melanocytes. We found that dGK mRNA and protein expression was considerably higher in melanoma cells than in a leukemic cell line, while the difference at the activity level was less profound.

    Downregulation of dGK in the melanoma cell line RaH5 using siRNA led to a compensatory increase in TK2 activity, which led to significantly increased sensitivity of the cells to gemcitabine. In contrast, downregulation of dGK in the human leukemic CEM cell line decreased TK2 activity, and rendered the cells more resistant to the drugs. The compensatory regulation of deoxynucleoside kinases with over-lapping substrate specificity differed in leukemic and melanoma cell lines probably because they preferably rely on different deoxynucleoside kinases for nucleoside and nucleoside analog activation. dGK and TK2 that are both located in the mitochondria, seems to be able to compensate for each other to a higher extent in the dGK-dependent melanoma cells compared to CEM cells that possess high dCK activity. Solid tumors, such as melanoma, expressing high levels of dGK should be considered for nucleoside analog therapy preferably in combination with their standard treatment.

  • 7.
    Fyrberg, Anna
    et al.
    Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Department of Medical and Health Sciences, Division of Drug Research.
    Lotfi, Kourosh
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Pharmacology.
    NUCLEOSIDE ANALOG ACTIVITY IN MALIGNANT MELANOMA CELL LINES2015In: Nucleosides, Nucleotides & Nucleic Acids, ISSN 1525-7770, E-ISSN 1532-2335, Vol. 34, no 9, p. 639-649Article in journal (Refereed)
    Abstract [en]

    Mitochondrial deoxyguanosine kinase (dGK), is an enzyme responsible for activation of nucleoside analogs (NAs) to phosphorylated compounds which exert profound cytotoxicity, especially in hematological malignancies. Screening malignant melanoma cell lines against NAs revealed high sensitivity to several of them. This was believed to be due to the high levels of dGK expression in these cells. Downregulation of dGK in the melanoma cell line RaH5 using siRNA did not cause resistance to NAs as expected, but instead cells became more sensitive. This was probably partly due to the increased activity of another mitochondrial enzyme, thymidine kinase 2, seen in transfected cells.

  • 8.
    Fyrberg, Anna
    et al.
    Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology . Linköping University, Faculty of Health Sciences.
    Lotfi, Kourosh
    Linköping University, Department of Medicine and Health Sciences, Clinical Pharmacology . Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Pharmacology.
    Optimization and evaluation of electroporation delivery of siRNA in the human leukemic CEM cell line2010In: CYTOTECHNOLOGY, ISSN 0920-9069, Vol. 62, no 6, p. 497-507Article in journal (Refereed)
    Abstract [en]

    In order to study nucleoside analog activation in the CEM cell line, a transfection protocol had to be optimized in order to silence an enzyme involved in nucleoside analog activation. Hematopoetic cell lines can be difficult to transfect with traditional lipid-based transfection, so the electroporation technique was used. Field strength, pulse length, temperature, electroporation media, siRNA concentration, among other conditions were tested in order to obtain approximately 70-80% mRNA and enzyme activity downregulation of the cytosolic enzyme deoxycytidine kinase (dCK), necessary for nucleoside analog activation. Downregulation was assessed at mRNA and enzyme activity levels. After optimizing the protocol, a microarray analysis was performed in order to investigate whether the downregulation was specific. Additionally two genes were differentially expressed besides the downregulation of dCK. These were however of unknown function. The leakage of intracellular nucleotides was also addressed in the electroporated cells since it can affect the DNA repair mechansism and the efficiency of nucleoside analogs. Three of these pools were increased compared to untreated, unelectroporated cells. The siRNA transfected cells with reduced dCK expression and activity showed reduced sensitivity to several nucleoside analogs as expected. The multidrug resistance to other drugs, as seen in nucleoside analog-induced resistant cells, was not seen with this model.

  • 9.
    Fyrberg, Anna
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Pharmacology.
    Mirzaee, S
    Lotfi, Kourosh
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Care, Clinical Pharmacology. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Pharmacology.
    Cell cycle dependent regulation of deoxycytidine kinase, deoxyguanosine kinase, and cytosolic 5′-nucleotidase I activity in MOLT-4 cells2006In: Nucleosides, Nucleotides & Nucleic Acids, ISSN 1525-7770, E-ISSN 1532-2335, Vol. 25, no 9-11, p. 1201-1204Article in journal (Refereed)
    Abstract [en]

    Activation of nucleoside analogues is dependent on kinases and 5′-nucleotidases and the balance between the activity of these enzymes. The purpose of this study was to analyze deoxycytidine kinase, deoxyguanosine kinase, and 4 different 5′-nucleotidases during cell cycle progression in MOLT-4 cells. The activity of both kinases was cell cycle dependent and increased during proliferation while the activity of cytosolic 5′-nucleotidase I decreased. We could show that the kinase activity was higher than the total nucleotidase activity, which was unchanged or decreased during cell cycle progression. These data may be important in designing modern combination therapy with nucleoside analogues. Copyright © Taylor & Francis Group, LLC.

  • 10.
    Fyrberg, Anna
    et al.
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Peterson, Curt
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Surgery, Orthopaedics and Cancer Treatment, Department of Oncology UHL.
    Kågedal, Bertil
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Diagnostics, Department of Clinical Chemistry.
    Lotfi, Kourosh
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Diagnostics, Department of Clinical Pharmacology.
    Induction of fetal hemoglobin and ABCB1 gene expression in 9-β-D-arabinofuranosylguanine-resistant MOLT-4 cells2011In: Cancer Chemotherapy and Pharmacology, ISSN 0344-5704, E-ISSN 1432-0843, Vol. 68, no 3, p. 583-591Article in journal (Refereed)
    Abstract [en]

    PURPOSE: To characterize resistance mechanisms to the nucleoside analog 9-β-D-arabinofuranosylguanine (AraG) in the T-cell acute lymphoblastic leukemia cell line MOLT-4 and its AraG-resistant variant.

    METHODS: A gene expression microarray analysis was performed, as well as gene expression and enzyme activity measurements of key enzymes in the activation of AraG. Cytotoxicity of AraG and cross-resistance to other compounds were evaluated using a standard cytotoxicity assay.

    RESULTS: Gene expression microarray analysis revealed that fetal hemoglobin genes and the multidrug resistance ABCB1 gene, encoding the drug efflux pump P-gp, were the most highly upregulated genes in the resistant cells, while genes traditionally associated with nucleoside analog resistance were not. Fetal hemoglobin and ABCB1 induction can be due to global DNA hypomethylation. This phenomenon was studied using AraG during a period of 4 weeks in MOLT-4 cells and the lung adenocarcinoma cell line A549, leading to up-regulation of hemoglobin gamma and ABCB1 as well as DNA hypomethylation. Inhibiting P-gp in the AraG-resistant MOLT-4 cells led to decreased proliferation, reduced hemoglobin expression, and highly induced ABCB1 expression.

    CONCLUSIONS: We show that AraG can cause hypomethylation of DNA and induce the expression of the fetal hemoglobin gamma gene and the ABCB1 gene. We speculate that the induction of ABCB1/P-gp may occur in order to help with excretion of hemoglobin degradation products that would otherwise be toxic to the cells, and we present data supporting our theory that P-gp may be linked to the induction of hemoglobin.

  • 11.
    Fyrberg, Anna
    et al.
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Skoglund, Karin
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Wolk, M
    Israel Minist Health Central Labs, Israel .
    Lotfi, Kourosh
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Diagnostics, Department of Clinical Pharmacology.
    A potential role of fetal hemoglobin in the development of multidrug resistance2012In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 427, no 3, p. 456-460Article in journal (Refereed)
    Abstract [en]

    Our previous data from a human leukemic cell line made resistant to the nucleoside analog (NA) 9-beta-D-arabinofuranosylguanine (AraG) revealed a massive upregulation of fetal hemoglobin (HbF) genes and the ABCB1 gene coding for the multidrug resistance P-glycoprotein (P-gp). The expression of these genes is regulated through the same mechanisms, with activation of the p38-MAPK pathway and inhibition of methylation making transcription factors more accessible to activate these genes. We could show that AraG, as well as other NAs, and P-gp substrates could induce global DNA demethylation and induction of Hb gamma and P-gp both at the mRNA and protein expression level. We speculate that the expression of HbF prior to drug exposure or in drug-resistant cell lines is a strategy of the cancer to gain more oxygen, and thereby survival benefits. We also believe that P-gp may be induced in order to excrete Hb degradation products from the cells that would otherwise be toxic. By using Hb gamma siRNA and pharmacological inhibitors of HbF production we here present a possible relationship between HbF induction and multi-drug resistance in a human leukemia cell line model.

  • 12.
    Jakobsen Falk, I. A.
    et al.
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Health Sciences.
    Green, K. H. Z.
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Health Sciences.
    Lotfi, Kourosh
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Diagnostics, Department of Clinical Pharmacology.
    Fyrberg, Anna
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    CORRELATION BETWEEN CYTIDINE DEAMINASE SINGLE NUCLEOTIDE POLYMORPHISMS AND DNA METHYLATION IN ACUTE MYELOGENOUS LEUKEMIA in ANNALS OF ONCOLOGY, vol 23, issue , pp 14-142012In: ANNALS OF ONCOLOGY, Oxford University Press (OUP): Policy A1 , 2012, Vol. 23, p. 14-14Conference paper (Refereed)
    Abstract [en]

    n/a

  • 13.
    Jakobsen Falk, Ingrid
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Fyrberg, Anna
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Paul, Esbjorn
    Karolinska Institute, Sweden.
    Nahi, Hareth
    Karolinska Institute, Sweden.
    Hermanson, Monica
    Uppsala University, Sweden.
    Rosenquist, Richard
    Uppsala University, Sweden.
    Hoglund, Martin
    Uppsala University, Sweden.
    Palmqvist, Lars
    University of Gothenburg, Sweden.
    Stockelberg, Dick
    Sahlgrens University Hospital, Sweden.
    Wei, Yuan
    Sahlgrens University Hospital, Sweden.
    Green, Henrik
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences. KTH Royal Institute Technology, Sweden.
    Lotfi, Kourosh
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Pharmacology.
    Impact of ABCB1 single nucleotide polymorphisms 1236C>T and 2677G>T on overall survival in FLT3 wild-type de novo AML patients with normal karyotype2014In: British Journal of Haematology, ISSN 0007-1048, E-ISSN 1365-2141, Vol. 167, no 5, p. 671-680Article in journal (Refereed)
    Abstract [en]

    Drug resistance is a clinically relevant problem in the treatment of acute myeloid leukaemia (AML). We have previously reported a relationship between single nucleotide polymorphisms (SNPs) of ABCB1, encoding the multi-drug transporter P-glycoprotein, and overall survival (OS) in normal karyotype (NK)-AML. Here we extended this material, enabling subgroup analysis based on FLT3 and NPM1 status, to further elucidate the influence of ABCB1 SNPs. De novo NK-AML patients (n = 201) were analysed for 1199Ggreater thanA, 1236Cgreater thanT, 2677Ggreater thanT/A and 3435Cgreater thanT, and correlations to outcome were investigated. FLT3 wild-type 1236C/C patients have significantly shorter OS compared to patients carrying the variant allele; medians 20 vs. 49 months, respectively, P = 0.017. There was also an inferior outcome in FLT3 wild-type 2677G/G patients compared to patients carrying the variant allele, median OS 20 vs. 35 months, respectively, P = 0.039. This was confirmed in Cox regression analysis. Our results indicate that ABCB1 1236Cgreater thanT and 2677Ggreater thanT may be used as prognostic markers to distinguish relatively high risk patients in the intermediate risk FLT3 wild-type group, which may contribute to future individualizing of treatment strategies.

  • 14.
    Jakobsen Falk, Ingrid
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Fyrberg, Anna
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Paul, Esbjörn
    Karolinska Institutet, Stockholm, Sweden.
    Nahi, Hareth
    Karolinska Institutet, Stockholm, Sweden.
    Hermanson, Monica
    Uppsala University, Sweden.
    Rosenquist, Richard
    Uppsala University, Sweden.
    Höglund, Martin
    University of Gothenburg, Sweden.
    Palmqvist, Lars
    University of Gothenburg, Sweden.
    Stockelberg, Dick
    Sahlgrenska University Hospital, Gothenburg, Sweden.
    Wei, Yuan
    Sahlgrenska University Hospital, Gothenburg, Sweden.
    Gréen, Henrik
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Lotfi, Kourosh
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Pharmacology.
    Decreased survival in normal karyotype AML with single-nucleotide polymorphisms in genes encoding the AraC metabolizing enzymes cytidine deaminase and 5'-nucleotidase2013In: American Journal of Hematology, ISSN 0361-8609, E-ISSN 1096-8652, Vol. 88, no 12, p. 1001-1006Article in journal (Refereed)
    Abstract [en]

    De novo acute myeloid leukemia with normal karyotype (NK-AML) comprises a large group of patients with no common cytogenetic alterations and with a large variation in treatment response. Single-nucleotide polymorphisms (SNPs) in genes related to the metabolism of the nucleoside analogue AraC, the backbone in AML treatment, might affect drug sensitivity and treatment outcome. Therefore, SNPs may serve as prognostic biomarkers aiding clinicians in individualized treatment decisions, with the aim of improving patient outcomes. We analyzed polymorphisms in genes encoding cytidine deaminase (CDA 79A>C rs2072671 and −451C>T rs532545), 5′-nucleotidase (cN-II 7A>G rs10883841), and deoxycytidine kinase (DCK 3′UTR 948T>C rs4643786) in 205 de novo NK-AML patients. In FLT3-internal tandem duplication (ITD)-positive patients, the CDA 79C/C and −451T/T genotypes were associated with shorter overall survival compared to other genotypes (5 vs. 24 months, P < 0.001 and 5 vs. 23 months, P = 0.015, respectively), and this was most pronounced in FLT3-ITD-positive/NPM1-positive patients. We observed altered in vitro sensitivity to topoisomerase inhibitory drugs, but not to nucleoside analogues, and a decrease in global DNA methylation in cells carrying both CDA variant alleles. A shorter survival was also observed for the cN-II variant allele, but only in FLT3-ITD-negative patients (25 vs. 31 months, P = 0.075). Our results indicate that polymorphisms in genes related to nucleoside analog drug metabolism may serve as prognostic markers in de novo NK-AML

  • 15.
    Lotfi, Kourosh
    et al.
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Pharmacology.
    Karlsson, Karin
    Östergötlands Läns Landsting, Centre of Surgery and Oncology, Department of Haematology UHL.
    Fyrberg, Anna
    Linköping University, Department of Medical and Health Sciences, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    Juliusson, Gunnar
    Lund University Hospital.
    Jonsson, Viggo
    Oslo University.
    Peterson, Curt
    Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Pharmacology.
    Eriksson, Staffan
    Swedish University of Agricultural Sciences, The Biomedical Center, Uppsala.
    Albertioni, Freidoun
    Linköping University, Department of Medicine and Care, Clinical Pharmacology. Linköping University, Faculty of Health Sciences.
    The pattern of deoxycytidine- and deoxyguanosine kinase activity in relation to messenger RNA expression in blood cells from untreated patients with B-cell chronic lymphocytic leukemia2006In: Biochemical Pharmacology, ISSN 0006-2952, E-ISSN 1356-1839, Vol. 71, no 6, p. 882-890Article in journal (Refereed)
    Abstract [en]

    Deoxycytidine kinase (dCK) and deoxyguanosine kinase (dGK) catalyze the first step in the intracellular cascade of fludarabine (2-fluoroadenine-β- d-arabinofuranoside) and cladribine (2-chlorodeoxyadenosine) phosphorylation, which leads to activation of these prodrugs, commonly used for treatment of chronic lymphocytic leukemia (CLL). Thus, resistance to nucleoside analogues may primarily be due to low levels of deoxynucleoside kinase activity. The purpose of this study was to investigate the activity profiles of dCK and dGK and characterize the possible relationship between the levels of dCK enzymatic activities and mRNA levels in B-CLL cells from untreated patient samples in an attempt to determine the best approach for predicting sensitivity to nucleoside analogues and thereby optimizing treatment of CLL. For this purpose, dCK and dGK analyses were done in blood cells from 59 untreated symptomatic patients with CLL. The dGK activity towards 2-chlorodeoxyadenosine was significantly lower than of dCK (median 73 pmol/mg protein/min (85-121, 95% CI) versus 353 pmol/mg protein/min (331-421)). The median dCK mRNA level was 0.107 (0.096-0.120, 95% CI). There was a lack of correlation between the activities of dCK and dGK, which indicates that these proteins are regulated independently. We also found that the dCK and dGK activity measurement towards their endogenous substrates were comparable to the nucleoside analogues tested. Such variations in enzyme activities and mRNA levels may well explain differences in clinical responses to treatment. There was no correlation between the levels of dCK mRNAs and enzymatic activities using a quantitative real-time PCR procedure. Sequencing of dCK mRNA did not reveal alternate splicing or mutations in the coding region. The relation between activity and mRNA levels was studied by short interfering RNA (siRNA) method, which showed that in the siRNA treated cells the down-regulation of dCK expression, and activity followed each other. However, in control cells the mRNA levels remained stable but the protein activity markedly decreased. These data demonstrate that the dCK activity is not reflected by dCK mRNA expression that indicates a post-translational mechanism(s). © 2005 Elsevier Inc. All rights reserved.

1 - 15 of 15
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf