NKL Homeobox Genes NKX2-3 and NKX2-4 Deregulate Megakaryocytic-Erythroid Cell Differentiation in AML.

Stefan Nagel,Corinna Meyer,Claudia Pommerenke,Roderick A F Macleod

doi:10.3390/ijms222111434

Abstract

NKL homeobox genes encode transcription factors that impact normal development and hematopoietic malignancies if deregulated. Recently, we established an NKL-code that describes the physiological expression pattern of eleven NKL homeobox genes in the course of hematopoiesis, allowing evaluation of aberrantly activated NKL genes in leukemia/lymphoma. Here, we identify ectopic expression of NKL homeobox gene NKX2-4 in an erythroblastic acute myeloid leukemia (AML) cell line OCI-M2 and describe investigation of its activating factors and target genes. Comparative expression profiling data of AML cell lines revealed in OCI-M2 an aberrantly activated program for endothelial development including master factor ETV2 and the additional endothelial signature genes HEY1, IRF6, and SOX7. Corresponding siRNA-mediated knockdown experiments showed their role in activating NKX2-4 expression. Furthermore, the ETV2 locus at 19p13 was genomically amplified, possibly underlying its aberrant expression. Target gene analyses of NKX2-4 revealed activated ETV2, HEY1, and SIX5 and suppressed FLI1. Comparative expression profiling analysis of public datasets for AML patients and primary megakaryocyte–erythroid progenitor cells showed conspicuous similarities to NKX2-4 activating factors and the target genes we identified, supporting the clinical relevance of our findings and developmental disturbance by NKX2-4. Finally, identification and target gene analysis of aberrantly expressed NKX2-3 in AML patients and a megakaryoblastic AML cell line ELF-153 showed activation of FLI1, contrasting with OCI-M2. FLI1 encodes a master factor for myelopoiesis, driving megakaryocytic differentiation and suppressing erythroid differentiation, thus representing a basic developmental target of these homeo-oncogenes. Taken together, we have identified aberrantly activated NKL homeobox genes NKX2-3 and NKX2-4 in AML, deregulating genes involved in megakaryocytic and erythroid differentiation processes, and thereby contributing to the formation of specific AML subtypes.

Highlights

Introduction published maps and institutional affilStem and progenitor cells pass through several developmental stages and subsequently differentiate into mature cells and tissues
We found that NKX2-4 is aberrantly connected with the developmental E26 transformation-specific (ETS) genes ETV2 and FLI1, generating a leukemogenic network, which impacts myeloid differentiation
The results showed that all three factors—IRF6, ETV2 and HEY1—activated

Summary

Introduction

Stem and progenitor cells pass through several developmental stages and subsequently differentiate into mature cells and tissues. Hematopoietic and endothelial cells share a common progenitor, termed hemangioblast. Later in development, these cell types differentiate separately, starting from hematopoietic and endothelial stem cells, respectively. The process of hematopoiesis generates all types of blood and immune cells, split into the lymphoid and myeloid lineages. The latter produces mature cell types such as erythrocytes and megakaryocytes via the joint megakaryocyte and erythroid progenitor [1].

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