Abstract A39: Nuclear SET domain (NSD) protein lysine methyltransferases (KMT) are higher expressed in acute myeloid leukemia

Abstract

Abstract The nuclear SET domain (NSD) protein lysine methyltransferases (KMT) family is composed of three members, NSD1/KMT3B, NSD2/WHSC1/MMSET, and NSD3/WHSC1L1, which regulate gene expression through methylation of lysine 36 of histone H3 (H3K36). NSD2 overexpression was reported in multiple myeloma with t(4;14)/IgH-MMSET. NSDs gene expression profile is unknown in acute leukemias; however, NSD1 and NSD3 were described to be fused with the nucleoporin 98 gene (NUP98) in rare AML and myelodysplastic syndrome cases and both fusion proteins were associated with poor prognosis. The aims of the present study were to characterize the expression of NSD-KMTs in patients with AML and healthy controls, to determine if this expression is associated with specific genetic abnormalities and/or with treatment outcome. Bone marrow aspirates from four healthy donors and 94 AML patients (50♀, 44♂) at diagnosis were included in the study. Our cohort included 10 patients with acute promyelocytic leukemia (APL), 8 with core binding factor (CBF) leukemias [6 with t(8;21) and 4 with inv(16)], and 74 patients with non-APL non-CBF AML. NSD family gene expression was evaluated by qPCR using the comparative Ct method for analysis. A higher expression of the NSD1 gene was observed in AML cells compared to normal bone marrow (BM) samples (median [range] = 3.8835 [0.6804-11.5598] vs. 1.003 [0.7956-1.265], p=0.0243). Similarly, the expression of NSD3 was higher in AML only for the comparison between healthy BM and CBF-AML groups (median [range] = 1.070 [0.6360-1.410] vs. 2.719 [1.238-8.830], p=0.0265). No significant differences were detected in the analysis of NSD2 expression. The association between expression levels of NSD-KMT with age, gender, prognosis (favorable vs. unfavorable), presence or absence of FLT3-ITD and NPM1 mutations, and presence or absence of karyotype abnormalities was evaluated. With the exception of NSD3 and presence/absence of karyotype abnormalities, NSD-KMT gene expression levels were higher in AML subgroups when compared to healthy donors, in all above parameters. NSD2 was more expressed in AML when compared to NSD1/NSD2 groups. NPM1 mutations and FLT3 internal tandem duplications (FLT3-ITD) were detected in 19.1% (18/94) of the patients with AML. NSD1/NSD3 were more expressed in FLT3-ITD mutant vs. FLT3 wild-type group. In addition, NSD2 was frequently more observed in patients aged 65 or older. Next, patients were stratified into two groups according to the median value of each NSD-KMT evaluated. We assessed the correlation between age, white blood cells count, hemoglobin, platelets, and blasts percentage at bone marrow and NSD-KMT expression levels. A positive correlation was observec between NSD1/NSD3 and the percentage of bone marrow blasts at diagnosis (r2 = 0.08080/p-value = 0.0084, and r2 = 0.04937/p-value = 0.0410, respectively). NSD3 was also correlated to the higher number of bone marrow blasts (r2 = 0.1219/p-value = 0.0217), followed by a decrease into the platelet count (r2 = 0.09795/p-value = 0.0436). Regarding the analysis of treatment outcome, patients with non-APL AML were stratified into high and low NSD1 or NSD2 expression subgroups using the criteria above. The median overall survival of patients in the low NSD2 expression subgroup was 333.023 days (95% CI:158.541-507.505 days) whereas that of patients in the high NSD2 expression subgroup was 817.629 days (95% CI:238.702-1396.555 days) (p=0,633). No significant difference was observed between the overall survival of patients in the high and low NSD1 expression subgroups. Our data suggest a correlation between the overexpression levels of NSD-KMT with histone modifications, suggesting that this modification and not only DNA methylation can contribute to epigenomic changes associated with AML pathogenesis. Citation Format: Virginia Mara de Deus Wagatsuma, Luisa C. A. Koury, Silvia Helena Sánchez, Lorena Lobo Figueiredo-Pontes, Fernanda Borges da Silva, Fernanda Borges da Silva, Adriana Ines Dore, Ana Silvia Gouvea de Lima, Antonio Roberto Lucena-Araujo, Fabiola Traina, Felipe Saldanha-Araujo, Fabio Pittella, Eduardo Magalhães Rego. Nuclear SET domain (NSD) protein lysine methyltransferases (KMT) are higher expressed in acute myeloid leukemia [abstract]. In: Proceedings of the AACR International Conference held in cooperation with the Latin American Cooperative Oncology Group (LACOG) on Translational Cancer Medicine; May 4-6, 2017; São Paulo, Brazil. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(1_Suppl):Abstract nr A39.