A heterozygous IDH1R132H/WT mutation induces genome-wide alterations in DNA methylation.
Monoallelic point mutations of the NADP(+)-dependent isocitrate dehydrogenases IDH1 and IDH2 occur frequently in gliomas, acute myeloid leukemias, and chondromas, and display robust association with specific DNA hypermethylation signatures. Here we show that heterozygous expression of the IDH1(R132H) allele is sufficient to induce the genome-wide alterations in DNA methylation characteristic of these tumors. Using a gene-targeting approach, we knocked-in a single copy of the most frequently observed IDH1 mutation, R132H, into a human cancer cell line and profiled changes in DNA methylation at over 27,000 CpG dinucleotides relative to wild-type parental cells. We find that IDH1(R132H/WT) mutation induces widespread alterations in DNA methylation, including hypermethylation of 2010 and hypomethylation of 842 CpG loci. We demonstrate that many of these alterations are consistent with those observed in IDH1-mutant and G-CIMP+ primary gliomas and can segregate IDH wild-type and mutated tumors as well as those exhibiting the G-CIMP phenotype in unsupervised analysis of two primary glioma cohorts. Further, we show that the direction of IDH1(R132H/WT)-mediated DNA methylation change is largely dependent upon preexisting DNA methylation levels, resulting in depletion of moderately methylated loci. Additionally, whereas the levels of multiple histone H3 and H4 methylation modifications were globally increased, consistent with broad inhibition of histone demethylation, hypermethylation at H3K9 in particular accompanied locus-specific DNA hypermethylation at several genes down-regulated in IDH1(R132H/WT) knock-in cells. These data provide insight on epigenetic alterations induced by IDH1 mutations and support a causal role for IDH1(R132H/WT) mutants in driving epigenetic instability in human cancer cells.
The Preston Robert Tisch Brain Tumor Center, The Pediatric Brain Tumor Foundation Institute, The Department of Pathology, Duke University Medical Center, Durham, North Carolina 27710, USA.
Christopher G
CG
Duncan
Benjamin G
BG
Barwick
Genglin
G
Jin
Carlo
C
Rago
Priya
P
Kapoor-Vazirani
Doris R
DR
Powell
Jen-Tsan
JT
Chi
Darell D
DD
Bigner
Paula M
PM
Vertino
Hai
H
Yan
D000483:Alleles; D015153:Blotting, Western; D047369:Chromatin Immunoprecipitation / Q000379:methods; D019175:DNA Methylation; D015536:Down-Regulation; D057890:Epigenomics; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D020868:Gene Silencing; D056426:Genetic Loci; D045325:HCT116 Cells; D006579:Heterozygote; D006657:Histones / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007521:Isocitrate Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D015470:Leukemia, Myeloid, Acute / Q000235:genetics; D009154:Mutation; D010641:Phenotype; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
D006657:Histones; D007521:Isocitrate Dehydrogenase; C543588:IDH1 protein, human