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Induction of fetal hemoglobin and ABCB1 gene expression in 9-β-D-arabinofuranosylguanine-resistant MOLT-4 cells
Linköpings universitet, Institutionen för medicin och hälsa, Klinisk farmakologi. Linköpings universitet, Hälsouniversitetet.
Linköpings universitet, Institutionen för medicin och hälsa, Klinisk farmakologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Centrum för kirurgi, ortopedi och cancervård, Onkologiska kliniken US.
Linköpings universitet, Institutionen för klinisk och experimentell medicin, Klinisk kemi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Diagnostikcentrum, Klinisk kemi.
Linköpings universitet, Institutionen för medicin och hälsa, Klinisk farmakologi. Linköpings universitet, Hälsouniversitetet. Östergötlands Läns Landsting, Diagnostikcentrum, Klinisk farmakologi.
2011 (Engelska)Ingår i: Cancer Chemotherapy and Pharmacology, ISSN 0344-5704, E-ISSN 1432-0843, Vol. 68, nr 3, s. 583-591Artikel i tidskrift (Refereegranskat) 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.

Ort, förlag, år, upplaga, sidor
Springer , 2011. Vol. 68, nr 3, s. 583-591
Nyckelord [en]
9-β-D-arabinofuranosylguanine - Fetal hemoglobin - P-glycoprotein - Microarray - Hypomethylation
Nationell ämneskategori
Medicin och hälsovetenskap
Identifikatorer
URN: urn:nbn:se:liu:diva-63246DOI: 10.1007/s00280-010-1524-5ISI: 000294345400004PubMedID: 21110023OAI: oai:DiVA.org:liu-63246DiVA, id: diva2:377209
Anmärkning
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||Tillgänglig från: 2010-12-13 Skapad: 2010-12-13 Senast uppdaterad: 2017-12-11
Ingår i avhandling
1. Nucleoside analoge cytotoxicity-focus on enzyme regulation, metabolism, and mechanisms of resistance
Öppna denna publikation i ny flik eller fönster >>Nucleoside analoge cytotoxicity-focus on enzyme regulation, metabolism, and mechanisms of resistance
2010 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
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.

Ort, förlag, år, upplaga, sidor
Linköping: Linköping University Electronic Press, 2010. s. 72
Serie
Linköping University Medical Dissertations, ISSN 0345-0082 ; 1209
Nationell ämneskategori
Farmakologi och toxikologi
Identifikatorer
urn:nbn:se:liu:diva-63247 (URN)978-91-7393-310-0 (ISBN)
Disputation
2010-12-10, Eken, Hälsouniversitetet, Campus US, Linköpings universitet, Linköping, 09:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2011-01-12 Skapad: 2010-12-13 Senast uppdaterad: 2018-01-12Bibliografiskt granskad

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