ABSTRACT
Acute myeloid leukemia (AML) occurs when multiple genetic aberrations alter white blood cell development, leading to hyperproliferation and arrest of cell differentiation. Pertinent animal models link in vitro studies with the use of new agents in clinical trials. We generated a transgenic zebrafish expressing human NUP98-HOXA9 (NHA9), a fusion oncogene found in high-risk AML. Embryos developed a preleukemic state with anemia and myeloid cell expansion, and adult fish developed a myeloproliferative neoplasm (MPN). We leveraged this model to show that NHA9 increases the number of hematopoietic stem cells, and that oncogenic function of NHA9 depends on downstream activation of meis1, the PTGS/COX pathway and genome hypermethylation through the DNA methyltransferase, dnmt1. We restored normal hematopoiesis in NHA9 embryos with knockdown of meis1 or dnmt1, as well as pharmacologic treatment with DNA (cytosine-5)-methyltransferase (DNMT) inhibitors or cyclo-oxygenase (COX) inhibitors. DNMT inhibitors reduced genome methylation to near normal levels. Strikingly, we discovered synergy when we combined sub-monotherapeutic doses of a histone deacetylase inhibitor plus either a DNMT inhibitor or COX inhibitor to block the effects of NHA9 on zebrafish blood development. Our work proposes novel drug targets in NHA9-induced myeloid disease, and suggests rational therapies by combining minimal doses of known bioactive compounds.
Subject(s)
Embryo, Nonmammalian/drug effects , Epigenesis, Genetic/drug effects , Hematopoiesis/physiology , Histone Deacetylase Inhibitors/therapeutic use , Homeodomain Proteins/genetics , Leukemia, Myeloid, Acute/prevention & control , Myeloproliferative Disorders/prevention & control , Nuclear Pore Complex Proteins/genetics , Oncogene Proteins, Fusion/genetics , Adult , Animals , Animals, Genetically Modified/genetics , Animals, Genetically Modified/metabolism , Biomarkers, Tumor/antagonists & inhibitors , Biomarkers, Tumor/genetics , Biomarkers, Tumor/metabolism , Cell Transformation, Neoplastic/drug effects , Cell Transformation, Neoplastic/metabolism , Cell Transformation, Neoplastic/pathology , Cells, Cultured , Embryo, Nonmammalian/cytology , Embryo, Nonmammalian/metabolism , Gene Expression Profiling , Hematopoiesis/drug effects , Humans , In Situ Hybridization , Leukemia, Myeloid, Acute/etiology , Leukemia, Myeloid, Acute/pathology , Myeloproliferative Disorders/etiology , Myeloproliferative Disorders/pathology , Oligonucleotide Array Sequence Analysis , Phenotype , Promoter Regions, Genetic/genetics , RNA, Messenger/genetics , Real-Time Polymerase Chain Reaction , Reverse Transcriptase Polymerase Chain Reaction , Transgenes/genetics , Zebrafish/embryology , Zebrafish/genetics , Zebrafish Proteins/geneticsABSTRACT
In all terrestrial and aquatic plant species the primary cell wall is a dynamic structure, adjusted to fulfil a diversity of functions. However a universal property is its considerable mechanical and tensile strength, whilst being flexible enough to accommodate turgor and allow for cell elongation. The wall is a composite material consisting of a framework of cellulose microfibrils embedded in a matrix of non-cellulosic polysaccharides, interlaced with structural proteins and pectic polymers. The assembly and modification of these polymers within the growing cell wall has, until recently, been poorly understood. Advances in cytological and genetic techniques have thrown light on these processes and have led to the discovery of a number of wall-modifying enzymes which, either directly or indirectly, play a role in the molecular basis of cell wall expansion.
