CDX2-driven leukemogenesis involves KLF4 repression and deregulated PPARγ signaling
Katrin Faber, Lars Bullinger, Christine Ragu, Angela Garding, Daniel Mertens, Christina Miller, Daniela Martin, Daniel Walcher, Konstanze Döhner, Hartmut Döhner, Rainer Claus, Christoph Plass, Stephen M. Sykes, Steven W. Lane, Claudia Scholl, Stefan Fröhling
Katrin Faber, Lars Bullinger, Christine Ragu, Angela Garding, Daniel Mertens, Christina Miller, Daniela Martin, Daniel Walcher, Konstanze Döhner, Hartmut Döhner, Rainer Claus, Christoph Plass, Stephen M. Sykes, Steven W. Lane, Claudia Scholl, Stefan Fröhling
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Research Article Oncology

CDX2-driven leukemogenesis involves KLF4 repression and deregulated PPARγ signaling

Abstract

Aberrant expression of the homeodomain transcription factor CDX2 occurs in most cases of acute myeloid leukemia (AML) and promotes leukemogenesis, making CDX2, in principle, an attractive therapeutic target. Conversely, CDX2 acts as a tumor suppressor in colonic epithelium. The effectors mediating the leukemogenic activity of CDX2 and the mechanism underlying its context-dependent properties are poorly characterized, and strategies for interfering with CDX2 function in AML remain elusive. We report data implicating repression of the transcription factor KLF4 as important for the oncogenic activity of CDX2, and demonstrate that CDX2 differentially regulates KLF4 in AML versus colon cancer cells through a mechanism that involves tissue-specific patterns of promoter binding and epigenetic modifications. Furthermore, we identified deregulation of the PPARγ signaling pathway as a feature of CDX2-associated AML and observed that PPARγ agonists derepressed KLF4 and were preferentially toxic to CDX2+ leukemic cells. These data delineate transcriptional programs associated with CDX2 expression in hematopoietic cells, provide insight into the antagonistic duality of CDX2 function in AML versus colon cancer, and suggest reactivation of KLF4 expression, through modulation of PPARγ signaling, as a therapeutic modality in a large proportion of AML patients.

Authors

Katrin Faber, Lars Bullinger, Christine Ragu, Angela Garding, Daniel Mertens, Christina Miller, Daniela Martin, Daniel Walcher, Konstanze Döhner, Hartmut Döhner, Rainer Claus, Christoph Plass, Stephen M. Sykes, Steven W. Lane, Claudia Scholl, Stefan Fröhling

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Figure 2

Relationship between CDX2 and KLF4 expression and analysis of the KLF4 regulatory region in human myeloid leukemia cell lines.

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Relationship between CDX2 and KLF4 expression and analysis of the KLF4 r...
(A) CDX2 mRNA expression. (B) KLF4 and CDKN1A mRNA levels in response to ectopic CDX2 expression. (C) KLF4 and CDKN1A mRNA levels in response to CDX2 knockdown. (D) Predicted KLF4 promoter (blue) and 4.6 kb upstream of the KLF4 TSS (+1). Possible CDX2 binding sites and the location of the corresponding PCR amplicons (italics) used for ChIP are indicated. The consensus sequence for binding of Cdx proteins is given in bold capital letters. H3K4me3 and H3K27me3 marks, detected in K-562 cells in the ENCODE Histone Modification ChIP-seq project by the Broad Institute, are indicated in red and green, respectively. (E) ChIP showing occupancy of sites 3 and 4 by HA-CDX2 in K-562. GAPDH served as control locus. (F) LUC reporter assays showing that site 3 is required for transcriptional silencing of KLF4 in response to ectopic CDX2 expression in K-562. Mutated sites are indicated by red crosses. (G) ChIP showing reduced H3K4me3 enrichment and unchanged H3K27me3 occupancy in K-562 upon expression of HA-CDX2. AFP and GAPDH served as negative and positive control loci for H3K4me3; GAPDH and SAT2 served as negative and positive control loci for H3K27me3. (H) Co-IP demonstrating interaction of HA-CDX2 with KDM5B in K-562. (I) ChIP showing increased H3K4me3 enrichment in K-562 stably transduced with HA-CDX2 upon KDM5B knockdown. AFP and GAPDH served as negative and positive control loci.