3055 – METALLOTHIONEIN 1 (MT1) AS A TARGETABLE DEPENDENCY IN ACUTE MYELOID LEUKEMIA

Abstract

Adult de novo acute myeloid leukemia (AML) is a blood cancer with poor prognosis. The heterogeneous nature of this disease motivates identification and understanding of specific dependencies within genetic and/or epigenetic subtypes of AML. The goal of this project is to understand the molecular mechanisms underlying AML development in the context of two recurrent and frequently co-mutated genes in human AML; the DNA methyltransferase DNMT3A and nucleophosmin NPM1. We used single-cell RNA-seq and cellHarmony analysis of our recently developed mouse model replicating DNMT3A and NPM1 mutations found in human AML to identify differentially expressed transcripts. Across four independently derived Dnmt3a;Npm1-mutant AML samples, metallothionein 1 (Mt1) was the top common, significantly upregulated transcript in the most primitive AML stem/progenitor cell compartment. MT-1 functions to protect against heavy metal toxicity, inflammation, oxidative stress, and has been implicated in cancer progression. This led us to hypothesize that upregulation of MT-1 is critical for growth and survival of DNMT3A;NPM1-mutant AML. First, we validated increased Mt1 expression using additional independent Dnmt3a;Npm1-mutant AML bone marrow and spleen samples compared to control wild-type cells. Next, using the DNMT3A;NPM1-mutant human AML cell line OCI-AML3, we found that MT-1 expression was increased 100-fold relative to a control human 293T cell line. To test the extent to which loss of Mt1 can inhibit growth of Dnmt3a;Npm1-mutant AML cells, we performed CRISPR-mediated knockout followed by ex vivo culture. We found that Mt1-knockout Dnmt3a;Npm1-mutant AML cells have reduced proliferation and expansion compared to control-targeted cells. Taken together, our study nominates MT-1 as a target towards the goal of treatment and prevention of DNMT3A;NPM1-mutant AML.