SummaryAcute myeloid leukemia (AML) is an aggressive cancer with a poor prognosis, for which mainstream treatments have not changed for decades. To identify additional therapeutic targets in AML, we optimize a genome-wide clustered regularly interspaced short palindromic repeats (CRISPR) screening platform and use it to identify genetic vulnerabilities in AML cells. We identify 492 AML-specific cell-essential genes, including several established therapeutic targets such as DOT1L, BCL2, and MEN1, and many other genes including clinically actionable candidates. We validate selected genes using genetic and pharmacological inhibition, and chose KAT2A as a candidate for downstream study. KAT2A inhibition demonstrated anti-AML activity by inducing myeloid differentiation and apoptosis, and suppressed the growth of primary human AMLs of diverse genotypes while sparing normal hemopoietic stem-progenitor cells. Our results propose that KAT2A inhibition should be investigated as a therapeutic strategy in AML and provide a large number of genetic vulnerabilities of this leukemia that can be pursued in downstream studies.

Acute myeloid leukemia (AML) is a molecularly diverse malignancy with a poor prognosis, whose largest subgroup is characterized by somatic mutations in NPM1, the gene for Nucleophosmin1. These mutations, termed NPM1c, result in cytoplasmic dislocation of Nucleophosmin1 and are associated with distinctive transcriptional signatures2, yet their role in leukemogenesis remains obscure. Here we report that activation of a humanized Npm1c knock-in allele in murine hemopoietic stem cells causes Hox overexpression, enhanced self-renewal and expanded myelopoiesis. One third of mice developed delayed-onset AML, suggesting a requirement for cooperating mutations. We identified such mutations using a Sleeping Beauty3-4 transposon which caused rapid-onset AML in 80% of Npm1c+ mice, associated with mutually exclusive integrations in Csf2, Flt3 or Rasgrp1 in 55 of 70 leukemias. Recurrent integrations were also identified in known and novel leukemia genes including Nf1, Bach2, Dleu2 and Nup98. Our results give new pathogenetic insights and identify therapeutic targets in NPM1c+ AML.

The histone H3 Lys27-specific demethylase UTX (or KDM6A) is targeted by loss-of-function mutations in multiple cancers. Here, we demonstrate that UTX suppresses myeloid leukemogenesis through noncatalytic functions, a property shared with its catalytically inactive Y-chromosome paralog, UTY (or KDM6C). In keeping with this, we demonstrate concomitant loss/mutation of KDM6A (UTX) and UTY in multiple human cancers. Mechanistically, global genomic profiling showed only minor changes in H3K27me3 but significant and bidirectional alterations in H3K27ac and chromatin accessibility; a predominant loss of H3K4me1 modifications; alterations in ETS and GATA-factor binding; and altered gene expression after Utx loss. By integrating proteomic and genomic analyses, we link these changes to UTX regulation of ATP-dependent chromatin remodeling, coordination of the COMPASS complex and enhanced pioneering activity of ETS factors during evolution to AML. Collectively, our findings identify a dual role for UTX in suppressing acute myeloid leukemia via repression of oncogenic ETS and upregulation of tumor-suppressive GATA programs.

Key Points• Npm1c and Nras-G12D comutation in mice leads to AML with a longer latency and a more mature phenotype than the Npm1c/Flt3-ITD combination.• Mutant Flt3 or Nras allele amplification is the dominant mode of progression in both Npm1c/Flt3-ITD and Npm1c/ Nras-G12D murine AML.NPM1 mutations define the commonest subgroup of acute myeloid leukemia (AML) and frequently co-occur with FLT3 internal tandem duplications (ITD) or, less commonly, NRAS or KRAS mutations. Co-occurrence of mutant NPM1 with FLT3-ITD carries a significantly worse prognosis than NPM1-RAS combinations. To understand the molecular basis of these observations, we compare the effects of the 2 combinations on hematopoiesis and leukemogenesis in knock-in mice. . During AML evolution, both models acquired additional copies of the mutant Flt3 or Nras alleles, but only Npm1 cA/1 ;Nras G12D/1 mice showed acquisition of other human AML mutations, including IDH1 R132Q. We also find, using primary Cas9-expressing AMLs, that Hoxa genes and selected interactors or downstream targets are required for survival of both types of double-mutant AML. Our results show that molecular complementarity underlies the higher frequency and significantly worse prognosis associated with NPM1c/FLT3-ITD vs NPM1/NRAS-G12D-mutant AML and functionally confirm the role of HOXA genes in

Long non-coding RNAs (lncRNAs) are important regulatory molecules that are implicated in cellular physiology and pathology. In this work, we dissect the functional role of the HOXB-AS3 lncRNA in patients with NPM1-mutated (NPM1mut) acute myeloid leukemia (AML). We show that HOXB-AS3 regulates the proliferative capacity of NPM1mut AML blasts in vitro and in vivo. HOXB-AS3 is shown to interact with the ErbB3-binding protein 1 (EBP1) and guide EBP1 to the ribosomal DNA locus. Via this mechanism, HOXB-AS3 regulates ribosomal RNA transcription and de novo protein synthesis. We propose that in the context of NPM1 mutations, HOXB-AS3 overexpression acts as a compensatory mechanism, which allows adequate protein production in leukemic blasts.