Apoptosis-Related Gene Expression Profiling in Hematopoietic Cell Fractions of MDS Patients.

Saskia Mc Langemeijer,Ruth Knops,Bert A Van Der Reijden,Theo De Witte,Joop H Jansen,Christian Gilissen,Rob Woestenenk,Niccolo Mariani,Gerwin Huls

doi:10.1371/journal.pone.0165582

Abstract

Although the vast majority of patients with a myelodysplastic syndrome (MDS) suffer from cytopenias, the bone marrow is usually normocellular or hypercellular. Apoptosis of hematopoietic cells in the bone marrow has been implicated in this phenomenon. However, in MDS it remains only partially elucidated which genes are involved in this process and which hematopoietic cells are mainly affected. We employed sensitive real-time PCR technology to study 93 apoptosis-related genes and gene families in sorted immature CD34+ and the differentiating erythroid (CD71+) and monomyeloid (CD13/33+) bone marrow cells. Unsupervised cluster analysis of the expression signature readily distinguished the different cellular bone marrow fractions (CD34+, CD71+ and CD13/33+) from each other, but did not discriminate patients from healthy controls. When individual genes were regarded, several were found to be differentially expressed between patients and controls. Particularly, strong over-expression of BIK (BCL2-interacting killer) was observed in erythroid progenitor cells of low- and high-risk MDS patients (both p = 0.001) and TNFRSF4 (tumor necrosis factor receptor superfamily 4) was down-regulated in immature hematopoietic cells (p = 0.0023) of low-risk MDS patients compared to healthy bone marrow.

Highlights

Myelodysplastic syndromes (MDS) represent a heterogeneous group of malignant hematopoietic disorders that are characterized by dysplasia in the myeloid, megakaryocytic and/or erythroid cell lineages
We have studied the expression of a large set of genes and gene families that have been associated with apoptosis in three different fluorescence activated cell sorting (FACS) isolated hematopoietic cell fractions from MDS patients and healthy controls
Using sensitive real-time PCR analysis followed by unsupervised clustering analysis of the measured gene expression levels, we were able to distinguish the

Summary

Introduction

Myelodysplastic syndromes (MDS) represent a heterogeneous group of malignant hematopoietic disorders that are characterized by dysplasia in the myeloid, megakaryocytic and/or erythroid cell lineages. Several studies have shown signs of increased apoptosis in bone marrow of MDS patients, using techniques such as in situ end labeling (ISEL) of fragmented DNA/ TUNEL assay [5,6,7], electron microscopy [8, 9], flowcytometry using annexin V staining [10,11,12] and measurement of mitochondrial membrane potential [11]. But not all studies apoptosis markers are elevated in the more indolent cases of MDS, whereas apoptosis is reduced or at normal levels in the more aggressive cases. This led to the hypothesis that apoptosis is initially increased in MDS due to either primary defects of the apoptotic pathway or in response to oncogenic stress. Others described that apoptosis is mainly increased in the more committed myeloid, erythroid and/or megakaryocytic lineages [8, 12, 13]

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Conclusion