Structural chromosomal rearrangements of the Nucleoporin 98 gene (NUP98), primarily balanced translocations and inversions, are associated with a wide array of hematopoietic malignancies. NUP98 is known to be fused to at least 28 different partner genes in patients with hematopoietic malignancies, including acute myeloid leukemia, chronic myeloid leukemia in blast crisis, myelodysplastic syndrome, acute lymphoblastic leukemia, and bilineage/biphenotypic leukemia. NUP98 gene fusions typically encode a fusion protein that retains the amino terminus of NUP98; in this context, it is important to note that several recent studies have demonstrated that the amino-terminal portion of NUP98 exhibits transcription activation potential. Approximately half of the NUP98 fusion partners encode homeodomain proteins, and at least 5 NUP98 fusions involve known histone-modifying genes. Several of the NUP98 fusions, including NUP98-homeobox (HOX)A9, NUP98-HOXD13, and NUP98-JARID1A, have been used to generate animal models of both lymphoid and myeloid malignancy; these models typically up-regulate HOXA cluster genes, including HOXA5, HOXA7, HOXA9, and HOXA10. In addition, several of the NUP98 fusion proteins have been shown to inhibit differentiation of hematopoietic precursors and to increase self-renewal of hematopoietic stem or progenitor cells, providing a potential mechanism for malignant transformation. (Blood. 2011;118(24): 6247-6257) IntroductionOne of the oldest, and most useful, whole genome screens for genes involved in malignant transformation is a simple karyotype of the malignant cell. 1 Analysis of recurrent, nonrandom chromosomal translocation breakpoints has identified numerous genes important for malignant transformation and provided critical insight into the biology, classification, and prognosis of hematopoietic malignancies. 2 The study of these genes (such as BCR-ABL and BCL2) has led to vastly improved therapy 3 and has opened an entire field of scientific inquiry. 4 The Nucleoporin 98 gene (NUP98) was originally identified as a structural component of the nuclear pore complex (NPC), 5 and was subsequently shown to be a fusion partner with homeobox (HOX)A9 in acute myeloid leukemia (AML) patients with a t(7;11) (p15;p15). 6,7 Twenty-eight distinct NUP98 gene fusions have been identified, caused primarily by balanced translocations and inversions, in the malignant cells of patients with a wide array of distinct hematopoietic malignancies, including AML, chronic myeloid leukemia in blast crisis (CML-bc), myelodysplastic syndrome (MDS), acute lymphoblastic leukemia (ALL), and bilineage/ biphenotypic leukemia. 8 In this overview, we present a summary of the known roles of NUP98 in normal cell physiology, the association of NUP98 fusion proteins with hematopoietic malignancies, the incidence and prognostic importance of these fusions, and the mechanisms by which NUP98 fusion oncoproteins contribute to the process of malignant transformation. Normal functions of NUP98NUP98 is a component of the NPC NUP98 is an ϳ 90...

In this report, we show that expression of a NUP98-PHF23 (NP23) fusion, associated with acute myeloid leukemia (AML) in humans, leads to myeloid, erythroid, T-cell, and B-cell leukemia in mice. The leukemic and pre-leukemic tissues display a stem cell-like expression signature including Hoxa, Hoxb, and Meis1 genes. The PHF23 PHD domain is known to bind H3K4me3 residues, and chromatin immunoprecipitation experiments demonstrated that the NP23 protein bound chromatin at a specific subset of H3K4me3 sites, including Hoxa, Hoxb, and Meis1. Treatment of NP23 cells with disulfiram, which inhibits the binding of PHD domains to H3K4me3 residues, rapidly and selectively killed NP23 myeloblasts; cell death was preceded by decreased expression of Hoxa, Hoxb, and Meis1. Furthermore, AML driven by a related fusion gene, NUP98-JARID1A (NJL), was also sensitive to disulfiram. Thus, the NP23 mouse provides a platform to evaluate compounds that disrupt binding of oncogenic PHD proteins to H3K4me3.