title: Effects of TET2 mutations on DNA methylation in chronic myelomonocytic leukemia.
abstract: TET2 enzymatically converts 5-methyl-cytosine to 5-hydroxymethyl-cytosine, possibly leading to loss of DNA methylation. TET2 mutations are common in myeloid leukemia and were proposed to contribute to leukemogenesis through DNA methylation. To expand on this concept, we studied chronic myelomonocytic leukemia (CMML) samples. TET2 missense or nonsense mutations were detected in 53% (16/30) of patients. In contrast, only 1/30 patient had a mutation in IDH1 or IDH2, and none of them had a mutation in DNMT3A in the sites most frequently mutated in leukemia. Using bisulfite pyrosequencing, global methylation measured by the LINE-1 assay and DNA methylation levels of 10 promoter CpG islands frequently abnormal in myeloid leukemia were not different between TET2 mutants and wild-type CMML cases. This was also true for 9 out of 11 gene promoters reported by others as differentially methylated by TET2 mutations. We found that two non-CpG island promoters, AIM2 and SP140, were hypermethylated in patients with mutant TET2. These were the only two gene promoters (out of 14,475 genes) previously found to be hypermethylated in TET2 mutant cases. However, total 5-methyl-cytosine levels in TET2 mutant cases were significantly higher than TET2 wild-type cases (median = 14.0% and 9.8%, respectively) (p = 0.016). Thus, TET2 mutations affect global methylation in CMML but most of the changes are likely to be outside gene promoters.
authors.affiliation: Department of Leukemia, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Jumpei
authors.initials: J
authors.lastname: Yamazaki
authors.forename: Rodolphe
authors.initials: R
authors.lastname: Taby
authors.forename: Aparna
authors.initials: A
authors.lastname: Vasanthakumar
authors.forename: Trisha
authors.initials: T
authors.lastname: Macrae
authors.forename: Kelly R
authors.initials: KR
authors.lastname: Ostler
authors.forename: Lanlan
authors.initials: L
authors.lastname: Shen
authors.forename: Hagop M
authors.initials: HM
authors.lastname: Kantarjian
authors.forename: Marcos R
authors.initials: MR
authors.lastname: Estecio
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Jelinek
authors.forename: Lucy A
authors.initials: LA
authors.lastname: Godley
authors.forename: Jean-Pierre J
authors.initials: JP
authors.lastname: Issa
mesh_terms: D044503:5-Methylcytosine / Q000378:metabolism; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D034961:Antigens, Nuclear / Q000235:genetics; D019175:DNA Methylation / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D049308:Dioxygenases; D005260:Female; D006801:Humans; D015477:Leukemia, Myelomonocytic, Chronic / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics
chemical_list: C410167:AIM2 protein, human; D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; C102470:SP140 protein, human; D014157:Transcription Factors; D044503:5-Methylcytosine; D049308:Dioxygenases; C541081:TET2 protein, human