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Profiling of H3K9me3 levels predicts Transcription Factor Activity and Survival in Acute Myeloid Leukemia

ABSTRACT: Acute Myeloid Leukemia (AML) is commonly associated with alterations in transcription factors due to altered expression or gene mutations. These changes might induce leukemia specific patterns of histone modifications. We used ChIP-Chip to analyze histone H3 Lysine 9 trimethylation (H3K9me3) patterns in primary AML (n=108), ALL (n=28), CD34+ cells (n=21) and white blood cells (n=15) specimens. Hundreds of promoter regions in AML showed significant alterations in H3K9me3 levels. H3K9me3 deregulation in AML occurred preferentially as a decrease in H3K9me3 levels at core promoter regions. The altered genomic regions showed an overrepresentation of cis-binding sites for ets and c-AMP response elements (CREs) for transcription factors of the CREB/CREM/ATF1 family. The decrease in H3K9me3 levels at CREs was associated with increased CRE-driven promoter activity in AML blasts in vivo. AML specific H3K9me3 patterns were not associated with known cytogenetic abnormalities. But a signature derived from H3K9me3 patterns predicted event free survival in AML patients. Combination of the H3K9me3 signature with established clinical prognostic markers outperformed prognosis prediction based on clinical parameters alone. These findings demonstrate widespread changes of H3K9me3 levels at gene promoters in AML. Signatures of histone modification patterns are associated with patient prognosis in AML.

ORGANISM(S): Homo sapiens

PROVIDER: GSE20452 | GEO | 2010/08/22

SECONDARY ACCESSION(S): PRJNA125111

REPOSITORIES: GEO

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Project description:Epigenetic deregulation plays a critical role in the pathogenesis of Acute Myeloid Leukemia. But changes in histone modification patterns at the epigenome level still remain largely unknown. Here, we analyzed alterations of histone H3 acetylation patterns in a large number of patients with AML compared to CD34+ progenitor cells. Using ChIP-Chip assays, we demonstrate that AML blasts exhibit significant changes in Histone H3 acetylation levels at more than 1000 genomic loci. Importantly, at core promoter regions losses of H3 acetlyation levels prevailed which suggested that a large number of genes is epigenetically silenced in AML. The validation of identified genes led to the discovery of Peroxiredoxin 2 (PRDX2) as a potential tumor suppressor gene in AML. Peroxiredoxin-2 (PRDX2) was silenced in most AML patients by decreased Histone H3 acetylation and in almost 20% by promoter DNA hypermethylation. Low protein expression of the antioxidant PRDX2 gene was clinically associated with a poor prognosis in AML patients. Functionally, PRDX2 acted as an inhibitor of myeloid cell growth by reducing levels of reactive oxygen species generated in response to cytokines. A high level of PRDX2 expression inhibited myc-induced murine leukemogenesis whereas loss of PRDX2 increased myeloid cell proliferation and accelerated myc-induced leukemogenesis. Taken together, we identify widespread loss of Histone H3 acetylation at core promoter regions as a signature of AML blasts. Epigenome wide analyses of histone H3 acetylation led to the identification of PRDX2 as an epigenetically silenced growth suppressor that contributed to the malignant phenotype in AML. Blasts from patients with AML (n=72) were obtained at the time of diagnosis (in a few cases at first relapse). CD34+ progenitor cells (n=17) and white blood cells (n=16) were used as control samples. Immunoprecipitations were performed for anti-acetylated Histone H3. Chromatin-IPs were amplified using ligation mediated PCR and labeled using Cy3 coupled to incorporated amino-allyl-UTP. Common reference DNA consisting of a mixture of genomic DNA from AML patients was prepared, amplified and labeled in a similar way with Cy5.

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Profiling of H3K9me3 levels predicts Transcription Factor Activity and Survival in Acute Myeloid Leukemia

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