Abstract 557: Aberrant methylation of tumor-suppressor genes in pediatric myelodysplastic syndrome/acute myeloid leukemia

Abstract

Abstract Introduction: Not only somatic mutations, but also epigenetic modifications in acute myeloid leukemia (AML) are estimated to have a pivotal role in leukemogenesis and it could be a therapeutic target. Especially, aberrant methylation of the promotor region of tumor suppressor genes (TSGs) were the causative events in leukemogenesis, however, there was only limited information in pediatric myelodysplastic syndrome (MDS) and AML. Materials and Methods: We analyzed the aberrant methylation of promotor region of 25 TSGs in pediatric 7 low grade MDS, 4 advanced MDS and 22 AML patients by FAB classification by Methylation-Specific Multiplex Ligation-dependent Probe Amplification (MS-MLPA) method (10 Male, 12 female, 0-14 years old, median 6 years ols). Simultaneously, detection of SNVs, In/del, and copy number variants were also analyzed by target sequence of more than 150 leukemia related genes. Especially, specific chimeras were analyzed in each patient. Results: Total 12/22(54.5%) patients had more than one methylated TSGs (number of methylated TSGs was 0-5 in each patient, median 1). More than 20% of patients had methylated TSGs including CDKN2B, CADM1, CDH13 and ESR1. Especially, there was a specific methylation pattern of TSGs, for example, all (4/4) t(8;21) patients had CDH13 methylation, 3/4 (75%) patients with inv(16) had ESR1 mutation and normal karyotype did not. Normal control samples, complete remission samples, and low grade MDS samples were not completely methylated. All advanced MDS patients had 1 or 2 methylated TSGs. Simultaneously, several leukemogenic genes were mutated such as GATA1, IKZF1, KRAS, KIT, FLT3, SH2B3, PIK3CD, PU.1, SMARC1, ALK, etc. Several genes were deleted such as CTCF, RB1, SRP72, ATM, NF1, U2AF1 etc. Discussion: In adult MDS, the increased number of methylated TSGs correlated to the development of AML and the poor prognosis. In this study, a few TSGs were methylated as the adult study (Hess CJ., Leuk Lymphoma 2008), furthermore, many genes related to epigenetic modification such as ASXL1, TET2 and EZH2 were not mutated in this study. Recently, anti-methylation drug were used in adult MDS/AML, larger study will be needed for adjusted use of epigenetic modifier in pediatric MDS/AML. Citation Format: Akira Shimada, Hirotaka Kanzaki, Hisashi Ishida, Takehiro Matsubara, Michinori Aoe. Aberrant methylation of tumor-suppressor genes in pediatric myelodysplastic syndrome/acute myeloid leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 557.