Abstract 5152: Zebrafish models of myeloid malignancies produced through tet2 and asxl1 genomic editing

Abstract

Abstract Myelodysplastic syndromes (MDS) are one of the most common and most difficult to treat of all hematologic malignancies. MDS are diverse clonal disorders of hematopoietic stem cells in the bone marrow that cause dysplastic differentiation in developing progenitors leading to ineffective hematopoiesis, dangerously low circulating blood counts, and evolution to acute myeloid leukemia (AML). We sought to create a faithful zebrafish model of MDS, to study the altered molecular pathways and mechanisms underlying this disease and to provide a means to identify synthetic lethal relationships that can be exploited with small molecule inhibitors to selectively eliminate the mutant cells. Somatic loss-of-function mutations of the Ten-ElevenTranslocation-2 (TET2) and Additional Sex Combs Like 1 (ASXL1) genes are the most frequent clonal somatically acquired genetic abnormalities that have been identified in human MDS and other myeloid malignancies, such as chronic myelomonocytic leukemia (CMML). To generate a zebrafish model of MDS with tet2 and asxl1 loss, we used genome-editing technology to disrupt the zebrafish tet2 and asxl1 genes. The resultant tet2m/m mutant zebrafish are viable and fertile and exhibited normal embryonic and larval hematopoiesis, but developed myelodysplastic syndrome progressing to anemia at 24 months of age. asxl1 m/m mutant zebrafish are embryonic lethal with bone malformations. asxl1 m/m embryos show reduced numbers of hematopoietic and progenitor stem cells (HSPCs), a phenotype which is rescued by Tet2 loss. Combined loss of tet2 and asxl1 in the zebrafish leads to CMML at 5 months of age. These zebrafish lines provide animal models for small molecule and genetic screens in definitive HSPCs to identify synthetic lethal relationships and to dissect the pathways in hematopoietic cells that are altered by loss of function of tet2 and asxl1. Citation Format: Evisa Gjini, Marc Mansour, Jeffry Sander, Shuning He, Myunggon Ko, Yi Zhou, Scott Rodig, Keith Joung, Leonard Zon, Anjana Rao, Thomas Look. Zebrafish models of myeloid malignancies produced through tet2 and asxl1 genomic editing. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5152. doi:10.1158/1538-7445.AM2015-5152