5-Hydroxymethylcytosine correlates with epigenetic regulatory mutations, but may not have prognostic value in predicting survival in normal karyotype acute myeloid leukemia

// Jae-Sook Ahn 1, 2 , Hyeoung-Joon Kim 1, 2 , Yeo-Kyeoung Kim 1, 2 , Seung-Shin Lee 1 , Seo-Yeon Ahn 1 , Sung-Hoon Jung 1 , Deok-Hwan Yang 1 , Je-Jung Lee 1 , Hee Jeong Park 2 , Seung Hyun Choi 2 , Chul Won Jung 3 , Jun-Ho Jang 3 , Hee Je Kim 4 , Joon Ho Moon 5 , Sang Kyun Sohn 5 , Jong-Ho Won 6 , Sung-Hyun Kim 7 , Szardenings Michael 8 , Mark D. Minden 9 , Dennis Dong Hwan Kim 9 1 Hematology-Oncology, Chonnam National University Hwasun Hospital, Jeollanam-do, Republic of Korea 2 Genomic Research Center for Hematopoietic Diseases, Chonnam National University Hwasun Hospital, Jeollanam-do, Republic of Korea 3 Division of Hematology-Oncology, Samsung Medical Center, Seoul, Republic of Korea 4 Department of Hematology, Cancer Research Institute, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea 5 Department of Hematology-Oncology, Kyungpook National University Hospital, Daegu, Republic of Korea 6 Department of Hematology-Oncology, Soon Chun Hyang University Hospital, Seoul, Republic of Korea 7 Department of Hematology-Oncology, Dong-A University College of Medicine, Busan, Republic of Korea 8 Fraunhofer Institute for Cell Therapy and Immunology, Leipzig, Germany 9 Department of Medical Oncology and Hematology, Princess Margaret Cancer Centre, University of Toronto, Toronto, Canada Correspondence to: Hyeoung-Joon Kim, email: hjoonk@chonnam.ac.kr Keywords: TET2 , IDH1/2, 5hmC, normal karyotype, AML Received: July 25, 2016     Accepted: November 24, 2016     Published: December 26, 2016 ABSTRACT Stem cells display remarkably high levels of 5-hydroxymethylcytosine (5hmC). Both TET2 and IDH1/2 mutations can impair the production of 5hmC, thus decreasing 5hmC levels. TET2 or IDH1/2 mutations are commonly observed in acute myeloid leukemia (AML). However, the implications of 5hmC on survival in normal karyotype AML patients have not been fully evaluated. The 5hmC levels were analyzed in 375 patients using ELISA. The levels of 5hmC in DNA samples were converted to a log scale for the analysis and correlations with TET2 and/or IDH1/2 mutations were evaluated. The median 5hmC level was 0.065% (range 0.001–0.999). Mutation rates were 13.1% for TET2 mut , 6.7% for IDH1 mut , and 13.9% for IDH2 mut . The prevalence of TET2 and/or IDH1/2 was 33.1% (124/375). TET2 and IDH1 / 2 mutated patients had significantly lower levels of log(5hmC) compared with patients without TET2 or IDH1/2 mutations ( p 0.05). To identify its prognostic value, we sub-classified the levels of 5hmC into tertiles for 5hmC values. However, there was no significant association between the categories of 5hmC levels and survival or relapse risk (all p >0.05). Patients with TET2 or IDH1/2 mutations had lower levels of 5hmC. The 5hmC levels may not be predictive of survival in patients with normal karyotype AML.