Acute myeloid leukemia (AML) is the second most common type of leukemia and accounts for 80% of adult acute leukemia cases and is characterized by the accumulation of poorly or undifferentiated myeloid blast cells. Standard treatment includes chemotherapy, which if unsuccessful, is followed by more rigorous chemotherapy as well as stem cell transplantation. Considering most patients are over the age of 45, these more rigorous therapies are not always possible, and as such, new therapies must be developed. Furthermore, AML patients harboring a chromosomal rearrangement involving Multiple Lineage Leukemia (MLL) that results in the expression of an MLL fusion protein exhibit far worse prognoses than patients without. In recent years, Danio rerio (zebrafish) has emerged as a powerful model organism for investigating human blood malignancies due to the conservation of hematopoiesis between humans and zebrafish. The first objective of this study was to develop a transient transgenic AML model in zebrafish, and the second objective was to determine if co-treatment with two medications currently in human trials for AML, Venetoclax and Flavopiridol, would be more effective than using either drug individually. In order to develop a transient transgenic AML model, we first developed a DNA construct encoding a known mixed lineage leukemia (MLL) fusion protein associated with human AML, MLL-ENL, driven by the zebrafish lysozyme C (lyz) promoter, which drives myeloid specific expression in zebrafish. We then microinjected single-cell zebrafish embryos with DNA encoding lyz driven MLL-ENL along with transposase mRNA to facilitate the genomic integration of MLL-ENL. Injected embryos were first tested for MLL-ENL expression, and subsequently tested for AML phenotypic characteristics, via whole mount in-situ hybridization (WISH) at 72 hours post fertilization (hpf). First, WISH analysis utilizing a human MLL riboprobe verified MLL-ENL expression in injected embryos, and WISH analysis utilizing the same MLL riboprobe revealed an expansion and clustering of MLL positive cells in injected embryos, characteristic of an AML phenotype. Embryos injected with MLL-ENL DNA were then treated with either DMSO (vehicle), 200 nanomolar (nM) Venetoclax, 200 nM Flavopiridol, or 200 nM Venetoclax and 200 nM Flavopiridol from 24 hpf to 72 hpf. MLL WISH analysis of injected and treated embryos revealed a reduction in MLL positive cells in both Venetoclax treated embryos and Flavopiridol treated embryos, and an even greater reduction in MLL positive cells in embryos treated with both Venetoclax and Flavopiridol, compared to controls. Although further analysis is required to be confident, these data suggest that we successfully developed an AML transient transgenic model in zebrafish. Furthermore, these data suggest that Venetoclax and Flavopiridol co-treatment could yield better outcomes for AML patients than treatment with either drug individually.
| Identifer | oai:union.ndltd.org:vcu.edu/oai:scholarscompass.vcu.edu:etd-6686 |
| Date | 01 January 2018 |
| Creators | Belt, Alex J |
| Publisher | VCU Scholars Compass |
| Source Sets | Virginia Commonwealth University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Theses and Dissertations |
| Rights | © The Author |
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