EHA Library - The official digital education library of European Hematology Association (EHA)

OVEREXPRESSION OF THE TRANSCRIPTION FACTOR CDX2 IN HAEMATOPOIETIC STEM CELLS PREDISPOSES TO HAEMATOLOGICAL MALIGNANCIES
Author(s): ,
Therese Vu
Affiliations:
QIMR Berghofer Medical Research Institute,Brisbane,Australia
,
Jasmin Straube
Affiliations:
QIMR Berghofer Medical Research Institute,Brisbane,Australia
,
Axia Song
Affiliations:
QIMR Berghofer Medical Research Institute,Brisbane,Australia
,
Victoria Ling
Affiliations:
QIMR Berghofer Medical Research Institute,Brisbane,Australia
,
Claudia Scholl
Affiliations:
National Center for Tumor Diseases (NCT),Heidelberg,Germany;German Cancer Research Center (DKFZ),Heidelberg,Germany
,
Stefan Fröhling
Affiliations:
National Center for Tumor Diseases (NCT),Heidelberg,Germany;Heidelberg University Hospital,Heidelberg,Germany
,
Graham Magor
Affiliations:
Australian Centre for Blood Diseases,Melbourne,Australia
,
Andrew Perkins
Affiliations:
Australian Centre for Blood Diseases,Melbourne,Australia
,
Stefan Gröschel
Affiliations:
National Center for Tumor Diseases (NCT),Heidelberg,Germany
,
Jan-Philipp Mallm
Affiliations:
German Cancer Research Center (DKFZ),Heidelberg,Germany
Steven Lane
Affiliations:
QIMR Berghofer Medical Research Institute,Brisbane,Australia;Royal Brisbane and Women's Hospital,Brisbane,Australia
(Abstract release date: 05/17/18) EHA Library. Vu T. 06/17/18; 214629; S1592
Therese Vu
Therese Vu
Contributions
Abstract

Abstract: S1592

Type: Oral Presentation

Presentation during EHA23: On Sunday, June 17, 2018 from 08:30 - 08:45

Location: Room A10

Background

The caudal-related homeobox gene CDX2 is ectopically expressed in 90% of human acute myeloid leukaemia (AML), but not normal haematopoietic cells. Retroviral expression of Cdx2 causes AML in vivo, while CDX2 knockdown impairs growth of AML cell lines in vitro. These findings implicate Cdx2 overexpression as a clinically relevant event in leukaemogenesis, however existing studies have been limited by the requirement for ex vivo manipulation, retroviral overexpression and transplantation.

Aims

To understand the role of Cdx2 in de novo leukaemic transformation on a molecular and cellular level.

Methods

We generated an inducible transgenic mouse model whereby Cdx2 was specifically activated in haematopoietic stem cells (HSC) using the tamoxifen-inducible Scl-CreERT2. We performed immunophenotyping, whole exome sequencing, RNA-sequencing, ATAC-sequencing, and in vivo treatment of leukaemic mice with the hypomethylating agent Azacitidine.

Results

Scl-CreERT2:Cdx2 mice developed a dysplastic phenotype which progressed in some mice to either myelodysplastic syndrome (MDS, 35%), myeloproliferative/MDS overlap (20%) or acute leukaemia (25%) after a long latency. Competitive transplantation assays showed intrinsic loss of long-term HSC self-renewal. Transcriptional analysis revealed an anti-apoptotic, pro-proliferative gene signature, suggesting Cdx2 overexpression confers a pre-leukaemic phenotype permissive to transformation upon acquisition of secondary mutations. 

Mechanistically, Scl-CreERT2:Cdx2 mice showed marked depletion of long-term HSC and abnormal cell cycle regulation. Whole exome sequencing indicated that Cdx2 acute leukaemia developed in the presence of pathogenic secondary mutations including Ikzf1, Notch1 and Kit. ATAC-sequencing for chromatin accessibility revealed widespread chromatin changes at haematopoietic-specific enhancers. These motifs include Runx1, Pu.1:Irf8, C/ebpα and C/ebpβ, which are key lineage determinants in haematopoietic stem and progenitor cells. Intriguingly, we observed complete repression of Hox cluster genes, challenging the notion that HOX activation drives leukaemia transformation in CDX2-positive leukaemia.

Scl-CreERT2:Cdx2 leukaemias were treated with azacitidine, a hypomethylating agent approved for high-risk MDS and AML patients. Azacitidine treatment prolonged survival and decreased leukaemic burden, associated with in vivo differentiation and selective apoptosis of Kit-positive leukaemia stem cells.

Conclusion

Altogether, this work demonstrates that conditional Cdx2 expression in HSC is a novel, inducible model of de novo leukaemic transformation and reflects common genetic aberrations seen in human AML. This may help to identify tractable susceptibilities to target leukaemia cells and improve clinical outcomes.

Session topic: 24. Hematopoiesis, stem cells and microenvironment

Keyword(s): Azacitidine, Leukemia, Mouse model, transcription factor

Abstract: S1592

Type: Oral Presentation

Presentation during EHA23: On Sunday, June 17, 2018 from 08:30 - 08:45

Location: Room A10

Background

The caudal-related homeobox gene CDX2 is ectopically expressed in 90% of human acute myeloid leukaemia (AML), but not normal haematopoietic cells. Retroviral expression of Cdx2 causes AML in vivo, while CDX2 knockdown impairs growth of AML cell lines in vitro. These findings implicate Cdx2 overexpression as a clinically relevant event in leukaemogenesis, however existing studies have been limited by the requirement for ex vivo manipulation, retroviral overexpression and transplantation.

Aims

To understand the role of Cdx2 in de novo leukaemic transformation on a molecular and cellular level.

Methods

We generated an inducible transgenic mouse model whereby Cdx2 was specifically activated in haematopoietic stem cells (HSC) using the tamoxifen-inducible Scl-CreERT2. We performed immunophenotyping, whole exome sequencing, RNA-sequencing, ATAC-sequencing, and in vivo treatment of leukaemic mice with the hypomethylating agent Azacitidine.

Results

Scl-CreERT2:Cdx2 mice developed a dysplastic phenotype which progressed in some mice to either myelodysplastic syndrome (MDS, 35%), myeloproliferative/MDS overlap (20%) or acute leukaemia (25%) after a long latency. Competitive transplantation assays showed intrinsic loss of long-term HSC self-renewal. Transcriptional analysis revealed an anti-apoptotic, pro-proliferative gene signature, suggesting Cdx2 overexpression confers a pre-leukaemic phenotype permissive to transformation upon acquisition of secondary mutations. 

Mechanistically, Scl-CreERT2:Cdx2 mice showed marked depletion of long-term HSC and abnormal cell cycle regulation. Whole exome sequencing indicated that Cdx2 acute leukaemia developed in the presence of pathogenic secondary mutations including Ikzf1, Notch1 and Kit. ATAC-sequencing for chromatin accessibility revealed widespread chromatin changes at haematopoietic-specific enhancers. These motifs include Runx1, Pu.1:Irf8, C/ebpα and C/ebpβ, which are key lineage determinants in haematopoietic stem and progenitor cells. Intriguingly, we observed complete repression of Hox cluster genes, challenging the notion that HOX activation drives leukaemia transformation in CDX2-positive leukaemia.

Scl-CreERT2:Cdx2 leukaemias were treated with azacitidine, a hypomethylating agent approved for high-risk MDS and AML patients. Azacitidine treatment prolonged survival and decreased leukaemic burden, associated with in vivo differentiation and selective apoptosis of Kit-positive leukaemia stem cells.

Conclusion

Altogether, this work demonstrates that conditional Cdx2 expression in HSC is a novel, inducible model of de novo leukaemic transformation and reflects common genetic aberrations seen in human AML. This may help to identify tractable susceptibilities to target leukaemia cells and improve clinical outcomes.

Session topic: 24. Hematopoiesis, stem cells and microenvironment

Keyword(s): Azacitidine, Leukemia, Mouse model, transcription factor

By clicking “Accept Terms & all Cookies” or by continuing to browse, you agree to the storing of third-party cookies on your device to enhance your user experience and agree to the user terms and conditions of this learning management system (LMS).

Cookie Settings
Accept Terms & all Cookies