title: The hematopoietic tumor suppressor interferon regulatory factor 8 (IRF8) is upregulated by the antimetabolite cytarabine in leukemic cells involving the zinc finger protein ZNF224, acting as a cofactor of the Wilms' tumor gene 1 (WT1) protein.
abstract: The transcription factor interferon regulatory factor-8 (IRF8) is highly expressed in myeloid progenitors, while most myeloid leukemias show low or absent expression. Loss of IRF8 in mice leads to a myeloproliferative disorder, indicating a tumor-suppressive role of IRF8. The Wilms tumor gene 1 (WT1) protein represses the IRF8-promoter. The zinc finger protein ZNF224 can act as a transcriptional co-factor of WT1 and potentiate the cytotoxic response to the cytostatic drug cytarabine. We hypothesized that cytarabine upregulates IRF8 and that transcriptional control of IRF8 involves WT1 and ZNF224. Treatment of leukemic K562 cells with cytarabine upregulated IRF8 protein and mRNA, which was correlated to increased expression of ZNF224. Knock down of ZNF224 with shRNA suppressed both basal and cytarabine-induced IRF8 expression. While ZNF224 alone did not affect IRF8 promoter activity, ZNF224 partially reversed the suppressive effect of WT1 on the IRF8 promoter, as judged by luciferase reporter experiments. Coprecipitation revealed nuclear binding of WT1 and ZNF224, and by chromatin immunoprecipitation (ChIP) experiments it was demonstrated that WT1 recruits ZNF224 to the IRF8 promoter. We conclude that cytarabine-induced upregulation of the IRF8 in leukemic cells involves increased levels of ZNF224, which can counteract the repressive activity of WT1 on the IRF8-promoter.
authors.affiliation: Department of Hematology and Transfusion Medicine, Medical Faculty, University of Lund, Lund, Sweden. Electronic address: giorgia.montano@med.lu.se.
authors.forename: Giorgia
authors.initials: G
authors.lastname: Montano
authors.affiliation: Department of Hematology and Transfusion Medicine, Medical Faculty, University of Lund, Lund, Sweden. Electronic address: tove.ullmark@med.lu.se.
authors.forename: Tove
authors.initials: T
authors.lastname: Ullmark
authors.affiliation: Department of Hematology and Transfusion Medicine, Medical Faculty, University of Lund, Lund, Sweden. Electronic address: helena.jernmark_nilsson@med.lu.se.
authors.forename: Helena
authors.initials: H
authors.lastname: Jernmark-Nilsson
authors.affiliation: Department of Molecular Medicine, and Medical Biotechnology, University of Naples Federico II, Naples, Italy. Electronic address: sodaro@unina.it.
authors.forename: Gaetano
authors.initials: G
authors.lastname: Sodaro
authors.affiliation: Department of Hematology and Transfusion Medicine, Medical Faculty, University of Lund, Lund, Sweden. Electronic address: kristina.drott@med.lu.se.
authors.forename: Kristina
authors.initials: K
authors.lastname: Drott
authors.affiliation: Department of Molecular Medicine, and Medical Biotechnology, University of Naples Federico II, Naples, Italy. Electronic address: paola.costanzo@unina.it.
authors.forename: Paola
authors.initials: P
authors.lastname: Costanzo
authors.affiliation: Department of Hematology and Transfusion Medicine, Medical Faculty, University of Lund, Lund, Sweden. Electronic address: karina.vidovic@med.lu.se.
authors.forename: Karina
authors.initials: K
authors.lastname: Vidovic
authors.affiliation: Department of Hematology and Transfusion Medicine, Medical Faculty, University of Lund, Lund, Sweden. Electronic address: urban.gullberg@med.lu.se.
authors.forename: Urban
authors.initials: U
authors.lastname: Gullberg
mesh_terms: D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology*; D045744:Cell Line, Tumor; D003561:Cytarabine / Q000494:pharmacology*; D006801:Humans; D050835:Interferon Regulatory Factors / Q000502:physiology*; D007938:Leukemia / Q000473:pathology*; D015854:Up-Regulation / Q000187:drug effects*; D025721:WT1 Proteins / Q000378:metabolism*; D016335:Zinc Fingers; D000099185:Interferon Regulatory Factor-8
chemical_list: D000964:Antimetabolites, Antineoplastic; D003561:Cytarabine; D050835:Interferon Regulatory Factors; D025721:WT1 Proteins; D000099185:Interferon Regulatory Factor-8; C583751:WT1 protein, human
keywords: Cytarabine; IRF8; Leukemia; Transcription; WT1; ZNF224