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Exp Hematol. 2015 Apr;43(4):300-8.e1. doi: 10.1016/j.exphem.2014.11.011. Epub 2014 Dec 20.

A C-terminal mutant of CCAAT-enhancer-binding protein α (C/EBPα-Cm) downregulates Csf1r, a potent accelerator in the progression of acute myeloid leukemia with C/EBPα-Cm.

Author information

1
Division of Cellular Therapy, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.
2
Division of Cellular Therapy, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan; Division of Stem Cell Signaling, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan.
3
Department of Hematology, Juntendo University School of Medicine, Tokyo, Japan; Division of Radiation Information Registry, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan.
4
Department of Hematology, Juntendo University School of Medicine, Tokyo, Japan; Department of Hematology and Oncology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Hiroshima, Japan.
5
Genome Science Division, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan.
6
Division of Cellular Therapy, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan; Division of Stem Cell Signaling, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan. Electronic address: kitamura@ims.u-tokyo.ac.jp.

Abstract

Two types of CCAAT-enhancer-binding protein α (C/EBPα) mutants are found in acute myeloid leukemia (AML) patients: N-terminal frame-shift mutants (C/EBPα-N(m)) generating p30 as a dominant form and C-terminal basic leucine zipper domain mutants (C/EBPα-C(m)). We have previously shown that C/EBPα-K304_R323dup belonging to C/EBPα-C(m), but not C/EBPα-T60fsX159 belonging to C/EBPα-N(m), alone induced AML in mouse bone marrow transplantation (BMT) models. Here we show that various C/EBPα-C(m) mutations have a similar, but not identical, potential in myeloid leukemogenesis. Notably, like C/EBPα-K304_R323dup, any type of C/EBPα-C(m) tested (C/EBPα-S299_K304dup, K313dup, or N321D) by itself induced AML, albeit with different latencies after BMT; C/EBPα-N321D induced AML with the shortest latency. By analyzing the gene expression profiles of C/EBPα-N321D- and mock-transduced c-kit(+)Sca-1(+)Lin(-) cells, we identified Csf1r as a gene downregulated by C/EBPα-N321D. In addition, leukemic cells expressing C/EBPα-C(m) exhibited low levels of colony stimulating factor 1 receptor in mice. On the other hand, transduction with C/EBPα-N(m) did not influence Csf1r expression in c-kit(+)Sca-1(+)Lin(-) cells, implying a unique role for C/EBPα-C(m) in downregulating Csf1r. Importantly, Csf1r overexpression collaborated with C/EBPα-N321D to induce fulminant AML with leukocytosis in mouse BMT models to a greater extent than did C/EBPα-N321D alone. Collectively, these results suggest that C/EBPα-C(m)-mediated downregulation of Csf1r has a negative, rather than a positive, impact on the progression of AML involving C/EBPα-C(m), which might possibly be accelerated by additional genetic and/or epigenetic alterations inducing Csf1r upregulation.

PMID:
25534203
DOI:
10.1016/j.exphem.2014.11.011
[Indexed for MEDLINE]

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