Publication Date:
2010-11-19
Description:
Abstract 627 Myeloproliferative diseases (MPD) are clonal hematologic disorders that present with increased numbers of functional, mature, terminally differentiated myeloid elements. Even though genetic, biochemical and functional studies have provided important insights into the pathogenesis of MPDs, the role of epigenetic changes in disease pathobiology is not well elucidated. We performed the HELP assay to study genome-wide methylation patterns in cases of Polycythemia Vera (PV), Essential Thrombocytosis (ET) and Idiopathic Myelofibrosis (IMF) and compared it with normal matched controls. The HELP assay uses differential methylation specific digestion by HpaII and MspI followed by amplification, two color labeling and hybridization to quantitatively determine individual promoter CpG methylation of 25636 loci. Analysis of 26 MPD neutrophil samples comprising 9 cases of ET, 6 cases of PV and 11 Cases of IMF was performed and compared to normal healthy controls. Unsupervised clustering based on global methylation profiles showed that IMF cases formed a distinct epigenetic cluster, while PV and ET cases were more similar to the normal controls. Further analysis of epigenetic differences between these groups showed that PV and ET samples were characterized by aberrant hypermethylation when compared to controls and had 143 genes that were uniformly hypermethylated. These genes are involved in pathways regulated by the NF-Kb and HNF-4alpha transcription factors. IMF on the other hand was characterized by both aberrantly hyper (n=162) and hypomethylated (n=95) loci when compared to controls. The pathways affected by hypomethylated genes were involved in cytokine cell signaling and MAP kinases. We subsequently validated these observations in an independent set of 8 IMF cases compared to 8 age matched controls. Methylation profiles obtained from whole blood by the HELP assay were able to clearly separate IMF cases from controls demonstrating the validity of our observations. These changes were quantified on a whole genome level by the Luminometric methylation assay (LUMA) that also revealed significantly more hypomethylation in IMF when compared to PV and ET cases (49% hypomethylation in IMF vs. 38% in PV/ET, p
Print ISSN:
0006-4971
Electronic ISSN:
1528-0020
Topics:
Biology
,
Medicine
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